xref: /openbmc/linux/fs/btrfs/extent-tree.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 #include <linux/sched.h>
19 #include <linux/pagemap.h>
20 #include <linux/writeback.h>
21 #include <linux/blkdev.h>
22 #include <linux/sort.h>
23 #include <linux/rcupdate.h>
24 #include <linux/kthread.h>
25 #include <linux/slab.h>
26 #include <linux/ratelimit.h>
27 #include <linux/percpu_counter.h>
28 #include "hash.h"
29 #include "tree-log.h"
30 #include "disk-io.h"
31 #include "print-tree.h"
32 #include "volumes.h"
33 #include "raid56.h"
34 #include "locking.h"
35 #include "free-space-cache.h"
36 #include "free-space-tree.h"
37 #include "math.h"
38 #include "sysfs.h"
39 #include "qgroup.h"
40 
41 #undef SCRAMBLE_DELAYED_REFS
42 
43 /*
44  * control flags for do_chunk_alloc's force field
45  * CHUNK_ALLOC_NO_FORCE means to only allocate a chunk
46  * if we really need one.
47  *
48  * CHUNK_ALLOC_LIMITED means to only try and allocate one
49  * if we have very few chunks already allocated.  This is
50  * used as part of the clustering code to help make sure
51  * we have a good pool of storage to cluster in, without
52  * filling the FS with empty chunks
53  *
54  * CHUNK_ALLOC_FORCE means it must try to allocate one
55  *
56  */
57 enum {
58 	CHUNK_ALLOC_NO_FORCE = 0,
59 	CHUNK_ALLOC_LIMITED = 1,
60 	CHUNK_ALLOC_FORCE = 2,
61 };
62 
63 static int update_block_group(struct btrfs_trans_handle *trans,
64 			      struct btrfs_fs_info *fs_info, u64 bytenr,
65 			      u64 num_bytes, int alloc);
66 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
67 			       struct btrfs_fs_info *fs_info,
68 				struct btrfs_delayed_ref_node *node, u64 parent,
69 				u64 root_objectid, u64 owner_objectid,
70 				u64 owner_offset, int refs_to_drop,
71 				struct btrfs_delayed_extent_op *extra_op);
72 static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
73 				    struct extent_buffer *leaf,
74 				    struct btrfs_extent_item *ei);
75 static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
76 				      struct btrfs_fs_info *fs_info,
77 				      u64 parent, u64 root_objectid,
78 				      u64 flags, u64 owner, u64 offset,
79 				      struct btrfs_key *ins, int ref_mod);
80 static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
81 				     struct btrfs_fs_info *fs_info,
82 				     u64 parent, u64 root_objectid,
83 				     u64 flags, struct btrfs_disk_key *key,
84 				     int level, struct btrfs_key *ins);
85 static int do_chunk_alloc(struct btrfs_trans_handle *trans,
86 			  struct btrfs_fs_info *fs_info, u64 flags,
87 			  int force);
88 static int find_next_key(struct btrfs_path *path, int level,
89 			 struct btrfs_key *key);
90 static void dump_space_info(struct btrfs_fs_info *fs_info,
91 			    struct btrfs_space_info *info, u64 bytes,
92 			    int dump_block_groups);
93 static int btrfs_add_reserved_bytes(struct btrfs_block_group_cache *cache,
94 				    u64 ram_bytes, u64 num_bytes, int delalloc);
95 static int btrfs_free_reserved_bytes(struct btrfs_block_group_cache *cache,
96 				     u64 num_bytes, int delalloc);
97 static int block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv,
98 			       u64 num_bytes);
99 static int __reserve_metadata_bytes(struct btrfs_root *root,
100 				    struct btrfs_space_info *space_info,
101 				    u64 orig_bytes,
102 				    enum btrfs_reserve_flush_enum flush);
103 static void space_info_add_new_bytes(struct btrfs_fs_info *fs_info,
104 				     struct btrfs_space_info *space_info,
105 				     u64 num_bytes);
106 static void space_info_add_old_bytes(struct btrfs_fs_info *fs_info,
107 				     struct btrfs_space_info *space_info,
108 				     u64 num_bytes);
109 
110 static noinline int
111 block_group_cache_done(struct btrfs_block_group_cache *cache)
112 {
113 	smp_mb();
114 	return cache->cached == BTRFS_CACHE_FINISHED ||
115 		cache->cached == BTRFS_CACHE_ERROR;
116 }
117 
118 static int block_group_bits(struct btrfs_block_group_cache *cache, u64 bits)
119 {
120 	return (cache->flags & bits) == bits;
121 }
122 
123 void btrfs_get_block_group(struct btrfs_block_group_cache *cache)
124 {
125 	atomic_inc(&cache->count);
126 }
127 
128 void btrfs_put_block_group(struct btrfs_block_group_cache *cache)
129 {
130 	if (atomic_dec_and_test(&cache->count)) {
131 		WARN_ON(cache->pinned > 0);
132 		WARN_ON(cache->reserved > 0);
133 		kfree(cache->free_space_ctl);
134 		kfree(cache);
135 	}
136 }
137 
138 /*
139  * this adds the block group to the fs_info rb tree for the block group
140  * cache
141  */
142 static int btrfs_add_block_group_cache(struct btrfs_fs_info *info,
143 				struct btrfs_block_group_cache *block_group)
144 {
145 	struct rb_node **p;
146 	struct rb_node *parent = NULL;
147 	struct btrfs_block_group_cache *cache;
148 
149 	spin_lock(&info->block_group_cache_lock);
150 	p = &info->block_group_cache_tree.rb_node;
151 
152 	while (*p) {
153 		parent = *p;
154 		cache = rb_entry(parent, struct btrfs_block_group_cache,
155 				 cache_node);
156 		if (block_group->key.objectid < cache->key.objectid) {
157 			p = &(*p)->rb_left;
158 		} else if (block_group->key.objectid > cache->key.objectid) {
159 			p = &(*p)->rb_right;
160 		} else {
161 			spin_unlock(&info->block_group_cache_lock);
162 			return -EEXIST;
163 		}
164 	}
165 
166 	rb_link_node(&block_group->cache_node, parent, p);
167 	rb_insert_color(&block_group->cache_node,
168 			&info->block_group_cache_tree);
169 
170 	if (info->first_logical_byte > block_group->key.objectid)
171 		info->first_logical_byte = block_group->key.objectid;
172 
173 	spin_unlock(&info->block_group_cache_lock);
174 
175 	return 0;
176 }
177 
178 /*
179  * This will return the block group at or after bytenr if contains is 0, else
180  * it will return the block group that contains the bytenr
181  */
182 static struct btrfs_block_group_cache *
183 block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr,
184 			      int contains)
185 {
186 	struct btrfs_block_group_cache *cache, *ret = NULL;
187 	struct rb_node *n;
188 	u64 end, start;
189 
190 	spin_lock(&info->block_group_cache_lock);
191 	n = info->block_group_cache_tree.rb_node;
192 
193 	while (n) {
194 		cache = rb_entry(n, struct btrfs_block_group_cache,
195 				 cache_node);
196 		end = cache->key.objectid + cache->key.offset - 1;
197 		start = cache->key.objectid;
198 
199 		if (bytenr < start) {
200 			if (!contains && (!ret || start < ret->key.objectid))
201 				ret = cache;
202 			n = n->rb_left;
203 		} else if (bytenr > start) {
204 			if (contains && bytenr <= end) {
205 				ret = cache;
206 				break;
207 			}
208 			n = n->rb_right;
209 		} else {
210 			ret = cache;
211 			break;
212 		}
213 	}
214 	if (ret) {
215 		btrfs_get_block_group(ret);
216 		if (bytenr == 0 && info->first_logical_byte > ret->key.objectid)
217 			info->first_logical_byte = ret->key.objectid;
218 	}
219 	spin_unlock(&info->block_group_cache_lock);
220 
221 	return ret;
222 }
223 
224 static int add_excluded_extent(struct btrfs_fs_info *fs_info,
225 			       u64 start, u64 num_bytes)
226 {
227 	u64 end = start + num_bytes - 1;
228 	set_extent_bits(&fs_info->freed_extents[0],
229 			start, end, EXTENT_UPTODATE);
230 	set_extent_bits(&fs_info->freed_extents[1],
231 			start, end, EXTENT_UPTODATE);
232 	return 0;
233 }
234 
235 static void free_excluded_extents(struct btrfs_fs_info *fs_info,
236 				  struct btrfs_block_group_cache *cache)
237 {
238 	u64 start, end;
239 
240 	start = cache->key.objectid;
241 	end = start + cache->key.offset - 1;
242 
243 	clear_extent_bits(&fs_info->freed_extents[0],
244 			  start, end, EXTENT_UPTODATE);
245 	clear_extent_bits(&fs_info->freed_extents[1],
246 			  start, end, EXTENT_UPTODATE);
247 }
248 
249 static int exclude_super_stripes(struct btrfs_fs_info *fs_info,
250 				 struct btrfs_block_group_cache *cache)
251 {
252 	u64 bytenr;
253 	u64 *logical;
254 	int stripe_len;
255 	int i, nr, ret;
256 
257 	if (cache->key.objectid < BTRFS_SUPER_INFO_OFFSET) {
258 		stripe_len = BTRFS_SUPER_INFO_OFFSET - cache->key.objectid;
259 		cache->bytes_super += stripe_len;
260 		ret = add_excluded_extent(fs_info, cache->key.objectid,
261 					  stripe_len);
262 		if (ret)
263 			return ret;
264 	}
265 
266 	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
267 		bytenr = btrfs_sb_offset(i);
268 		ret = btrfs_rmap_block(fs_info, cache->key.objectid,
269 				       bytenr, 0, &logical, &nr, &stripe_len);
270 		if (ret)
271 			return ret;
272 
273 		while (nr--) {
274 			u64 start, len;
275 
276 			if (logical[nr] > cache->key.objectid +
277 			    cache->key.offset)
278 				continue;
279 
280 			if (logical[nr] + stripe_len <= cache->key.objectid)
281 				continue;
282 
283 			start = logical[nr];
284 			if (start < cache->key.objectid) {
285 				start = cache->key.objectid;
286 				len = (logical[nr] + stripe_len) - start;
287 			} else {
288 				len = min_t(u64, stripe_len,
289 					    cache->key.objectid +
290 					    cache->key.offset - start);
291 			}
292 
293 			cache->bytes_super += len;
294 			ret = add_excluded_extent(fs_info, start, len);
295 			if (ret) {
296 				kfree(logical);
297 				return ret;
298 			}
299 		}
300 
301 		kfree(logical);
302 	}
303 	return 0;
304 }
305 
306 static struct btrfs_caching_control *
307 get_caching_control(struct btrfs_block_group_cache *cache)
308 {
309 	struct btrfs_caching_control *ctl;
310 
311 	spin_lock(&cache->lock);
312 	if (!cache->caching_ctl) {
313 		spin_unlock(&cache->lock);
314 		return NULL;
315 	}
316 
317 	ctl = cache->caching_ctl;
318 	atomic_inc(&ctl->count);
319 	spin_unlock(&cache->lock);
320 	return ctl;
321 }
322 
323 static void put_caching_control(struct btrfs_caching_control *ctl)
324 {
325 	if (atomic_dec_and_test(&ctl->count))
326 		kfree(ctl);
327 }
328 
329 #ifdef CONFIG_BTRFS_DEBUG
330 static void fragment_free_space(struct btrfs_block_group_cache *block_group)
331 {
332 	struct btrfs_fs_info *fs_info = block_group->fs_info;
333 	u64 start = block_group->key.objectid;
334 	u64 len = block_group->key.offset;
335 	u64 chunk = block_group->flags & BTRFS_BLOCK_GROUP_METADATA ?
336 		fs_info->nodesize : fs_info->sectorsize;
337 	u64 step = chunk << 1;
338 
339 	while (len > chunk) {
340 		btrfs_remove_free_space(block_group, start, chunk);
341 		start += step;
342 		if (len < step)
343 			len = 0;
344 		else
345 			len -= step;
346 	}
347 }
348 #endif
349 
350 /*
351  * this is only called by cache_block_group, since we could have freed extents
352  * we need to check the pinned_extents for any extents that can't be used yet
353  * since their free space will be released as soon as the transaction commits.
354  */
355 u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
356 		       struct btrfs_fs_info *info, u64 start, u64 end)
357 {
358 	u64 extent_start, extent_end, size, total_added = 0;
359 	int ret;
360 
361 	while (start < end) {
362 		ret = find_first_extent_bit(info->pinned_extents, start,
363 					    &extent_start, &extent_end,
364 					    EXTENT_DIRTY | EXTENT_UPTODATE,
365 					    NULL);
366 		if (ret)
367 			break;
368 
369 		if (extent_start <= start) {
370 			start = extent_end + 1;
371 		} else if (extent_start > start && extent_start < end) {
372 			size = extent_start - start;
373 			total_added += size;
374 			ret = btrfs_add_free_space(block_group, start,
375 						   size);
376 			BUG_ON(ret); /* -ENOMEM or logic error */
377 			start = extent_end + 1;
378 		} else {
379 			break;
380 		}
381 	}
382 
383 	if (start < end) {
384 		size = end - start;
385 		total_added += size;
386 		ret = btrfs_add_free_space(block_group, start, size);
387 		BUG_ON(ret); /* -ENOMEM or logic error */
388 	}
389 
390 	return total_added;
391 }
392 
393 static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)
394 {
395 	struct btrfs_block_group_cache *block_group = caching_ctl->block_group;
396 	struct btrfs_fs_info *fs_info = block_group->fs_info;
397 	struct btrfs_root *extent_root = fs_info->extent_root;
398 	struct btrfs_path *path;
399 	struct extent_buffer *leaf;
400 	struct btrfs_key key;
401 	u64 total_found = 0;
402 	u64 last = 0;
403 	u32 nritems;
404 	int ret;
405 	bool wakeup = true;
406 
407 	path = btrfs_alloc_path();
408 	if (!path)
409 		return -ENOMEM;
410 
411 	last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
412 
413 #ifdef CONFIG_BTRFS_DEBUG
414 	/*
415 	 * If we're fragmenting we don't want to make anybody think we can
416 	 * allocate from this block group until we've had a chance to fragment
417 	 * the free space.
418 	 */
419 	if (btrfs_should_fragment_free_space(block_group))
420 		wakeup = false;
421 #endif
422 	/*
423 	 * We don't want to deadlock with somebody trying to allocate a new
424 	 * extent for the extent root while also trying to search the extent
425 	 * root to add free space.  So we skip locking and search the commit
426 	 * root, since its read-only
427 	 */
428 	path->skip_locking = 1;
429 	path->search_commit_root = 1;
430 	path->reada = READA_FORWARD;
431 
432 	key.objectid = last;
433 	key.offset = 0;
434 	key.type = BTRFS_EXTENT_ITEM_KEY;
435 
436 next:
437 	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
438 	if (ret < 0)
439 		goto out;
440 
441 	leaf = path->nodes[0];
442 	nritems = btrfs_header_nritems(leaf);
443 
444 	while (1) {
445 		if (btrfs_fs_closing(fs_info) > 1) {
446 			last = (u64)-1;
447 			break;
448 		}
449 
450 		if (path->slots[0] < nritems) {
451 			btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
452 		} else {
453 			ret = find_next_key(path, 0, &key);
454 			if (ret)
455 				break;
456 
457 			if (need_resched() ||
458 			    rwsem_is_contended(&fs_info->commit_root_sem)) {
459 				if (wakeup)
460 					caching_ctl->progress = last;
461 				btrfs_release_path(path);
462 				up_read(&fs_info->commit_root_sem);
463 				mutex_unlock(&caching_ctl->mutex);
464 				cond_resched();
465 				mutex_lock(&caching_ctl->mutex);
466 				down_read(&fs_info->commit_root_sem);
467 				goto next;
468 			}
469 
470 			ret = btrfs_next_leaf(extent_root, path);
471 			if (ret < 0)
472 				goto out;
473 			if (ret)
474 				break;
475 			leaf = path->nodes[0];
476 			nritems = btrfs_header_nritems(leaf);
477 			continue;
478 		}
479 
480 		if (key.objectid < last) {
481 			key.objectid = last;
482 			key.offset = 0;
483 			key.type = BTRFS_EXTENT_ITEM_KEY;
484 
485 			if (wakeup)
486 				caching_ctl->progress = last;
487 			btrfs_release_path(path);
488 			goto next;
489 		}
490 
491 		if (key.objectid < block_group->key.objectid) {
492 			path->slots[0]++;
493 			continue;
494 		}
495 
496 		if (key.objectid >= block_group->key.objectid +
497 		    block_group->key.offset)
498 			break;
499 
500 		if (key.type == BTRFS_EXTENT_ITEM_KEY ||
501 		    key.type == BTRFS_METADATA_ITEM_KEY) {
502 			total_found += add_new_free_space(block_group,
503 							  fs_info, last,
504 							  key.objectid);
505 			if (key.type == BTRFS_METADATA_ITEM_KEY)
506 				last = key.objectid +
507 					fs_info->nodesize;
508 			else
509 				last = key.objectid + key.offset;
510 
511 			if (total_found > CACHING_CTL_WAKE_UP) {
512 				total_found = 0;
513 				if (wakeup)
514 					wake_up(&caching_ctl->wait);
515 			}
516 		}
517 		path->slots[0]++;
518 	}
519 	ret = 0;
520 
521 	total_found += add_new_free_space(block_group, fs_info, last,
522 					  block_group->key.objectid +
523 					  block_group->key.offset);
524 	caching_ctl->progress = (u64)-1;
525 
526 out:
527 	btrfs_free_path(path);
528 	return ret;
529 }
530 
531 static noinline void caching_thread(struct btrfs_work *work)
532 {
533 	struct btrfs_block_group_cache *block_group;
534 	struct btrfs_fs_info *fs_info;
535 	struct btrfs_caching_control *caching_ctl;
536 	struct btrfs_root *extent_root;
537 	int ret;
538 
539 	caching_ctl = container_of(work, struct btrfs_caching_control, work);
540 	block_group = caching_ctl->block_group;
541 	fs_info = block_group->fs_info;
542 	extent_root = fs_info->extent_root;
543 
544 	mutex_lock(&caching_ctl->mutex);
545 	down_read(&fs_info->commit_root_sem);
546 
547 	if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
548 		ret = load_free_space_tree(caching_ctl);
549 	else
550 		ret = load_extent_tree_free(caching_ctl);
551 
552 	spin_lock(&block_group->lock);
553 	block_group->caching_ctl = NULL;
554 	block_group->cached = ret ? BTRFS_CACHE_ERROR : BTRFS_CACHE_FINISHED;
555 	spin_unlock(&block_group->lock);
556 
557 #ifdef CONFIG_BTRFS_DEBUG
558 	if (btrfs_should_fragment_free_space(block_group)) {
559 		u64 bytes_used;
560 
561 		spin_lock(&block_group->space_info->lock);
562 		spin_lock(&block_group->lock);
563 		bytes_used = block_group->key.offset -
564 			btrfs_block_group_used(&block_group->item);
565 		block_group->space_info->bytes_used += bytes_used >> 1;
566 		spin_unlock(&block_group->lock);
567 		spin_unlock(&block_group->space_info->lock);
568 		fragment_free_space(block_group);
569 	}
570 #endif
571 
572 	caching_ctl->progress = (u64)-1;
573 
574 	up_read(&fs_info->commit_root_sem);
575 	free_excluded_extents(fs_info, block_group);
576 	mutex_unlock(&caching_ctl->mutex);
577 
578 	wake_up(&caching_ctl->wait);
579 
580 	put_caching_control(caching_ctl);
581 	btrfs_put_block_group(block_group);
582 }
583 
584 static int cache_block_group(struct btrfs_block_group_cache *cache,
585 			     int load_cache_only)
586 {
587 	DEFINE_WAIT(wait);
588 	struct btrfs_fs_info *fs_info = cache->fs_info;
589 	struct btrfs_caching_control *caching_ctl;
590 	int ret = 0;
591 
592 	caching_ctl = kzalloc(sizeof(*caching_ctl), GFP_NOFS);
593 	if (!caching_ctl)
594 		return -ENOMEM;
595 
596 	INIT_LIST_HEAD(&caching_ctl->list);
597 	mutex_init(&caching_ctl->mutex);
598 	init_waitqueue_head(&caching_ctl->wait);
599 	caching_ctl->block_group = cache;
600 	caching_ctl->progress = cache->key.objectid;
601 	atomic_set(&caching_ctl->count, 1);
602 	btrfs_init_work(&caching_ctl->work, btrfs_cache_helper,
603 			caching_thread, NULL, NULL);
604 
605 	spin_lock(&cache->lock);
606 	/*
607 	 * This should be a rare occasion, but this could happen I think in the
608 	 * case where one thread starts to load the space cache info, and then
609 	 * some other thread starts a transaction commit which tries to do an
610 	 * allocation while the other thread is still loading the space cache
611 	 * info.  The previous loop should have kept us from choosing this block
612 	 * group, but if we've moved to the state where we will wait on caching
613 	 * block groups we need to first check if we're doing a fast load here,
614 	 * so we can wait for it to finish, otherwise we could end up allocating
615 	 * from a block group who's cache gets evicted for one reason or
616 	 * another.
617 	 */
618 	while (cache->cached == BTRFS_CACHE_FAST) {
619 		struct btrfs_caching_control *ctl;
620 
621 		ctl = cache->caching_ctl;
622 		atomic_inc(&ctl->count);
623 		prepare_to_wait(&ctl->wait, &wait, TASK_UNINTERRUPTIBLE);
624 		spin_unlock(&cache->lock);
625 
626 		schedule();
627 
628 		finish_wait(&ctl->wait, &wait);
629 		put_caching_control(ctl);
630 		spin_lock(&cache->lock);
631 	}
632 
633 	if (cache->cached != BTRFS_CACHE_NO) {
634 		spin_unlock(&cache->lock);
635 		kfree(caching_ctl);
636 		return 0;
637 	}
638 	WARN_ON(cache->caching_ctl);
639 	cache->caching_ctl = caching_ctl;
640 	cache->cached = BTRFS_CACHE_FAST;
641 	spin_unlock(&cache->lock);
642 
643 	if (fs_info->mount_opt & BTRFS_MOUNT_SPACE_CACHE) {
644 		mutex_lock(&caching_ctl->mutex);
645 		ret = load_free_space_cache(fs_info, cache);
646 
647 		spin_lock(&cache->lock);
648 		if (ret == 1) {
649 			cache->caching_ctl = NULL;
650 			cache->cached = BTRFS_CACHE_FINISHED;
651 			cache->last_byte_to_unpin = (u64)-1;
652 			caching_ctl->progress = (u64)-1;
653 		} else {
654 			if (load_cache_only) {
655 				cache->caching_ctl = NULL;
656 				cache->cached = BTRFS_CACHE_NO;
657 			} else {
658 				cache->cached = BTRFS_CACHE_STARTED;
659 				cache->has_caching_ctl = 1;
660 			}
661 		}
662 		spin_unlock(&cache->lock);
663 #ifdef CONFIG_BTRFS_DEBUG
664 		if (ret == 1 &&
665 		    btrfs_should_fragment_free_space(cache)) {
666 			u64 bytes_used;
667 
668 			spin_lock(&cache->space_info->lock);
669 			spin_lock(&cache->lock);
670 			bytes_used = cache->key.offset -
671 				btrfs_block_group_used(&cache->item);
672 			cache->space_info->bytes_used += bytes_used >> 1;
673 			spin_unlock(&cache->lock);
674 			spin_unlock(&cache->space_info->lock);
675 			fragment_free_space(cache);
676 		}
677 #endif
678 		mutex_unlock(&caching_ctl->mutex);
679 
680 		wake_up(&caching_ctl->wait);
681 		if (ret == 1) {
682 			put_caching_control(caching_ctl);
683 			free_excluded_extents(fs_info, cache);
684 			return 0;
685 		}
686 	} else {
687 		/*
688 		 * We're either using the free space tree or no caching at all.
689 		 * Set cached to the appropriate value and wakeup any waiters.
690 		 */
691 		spin_lock(&cache->lock);
692 		if (load_cache_only) {
693 			cache->caching_ctl = NULL;
694 			cache->cached = BTRFS_CACHE_NO;
695 		} else {
696 			cache->cached = BTRFS_CACHE_STARTED;
697 			cache->has_caching_ctl = 1;
698 		}
699 		spin_unlock(&cache->lock);
700 		wake_up(&caching_ctl->wait);
701 	}
702 
703 	if (load_cache_only) {
704 		put_caching_control(caching_ctl);
705 		return 0;
706 	}
707 
708 	down_write(&fs_info->commit_root_sem);
709 	atomic_inc(&caching_ctl->count);
710 	list_add_tail(&caching_ctl->list, &fs_info->caching_block_groups);
711 	up_write(&fs_info->commit_root_sem);
712 
713 	btrfs_get_block_group(cache);
714 
715 	btrfs_queue_work(fs_info->caching_workers, &caching_ctl->work);
716 
717 	return ret;
718 }
719 
720 /*
721  * return the block group that starts at or after bytenr
722  */
723 static struct btrfs_block_group_cache *
724 btrfs_lookup_first_block_group(struct btrfs_fs_info *info, u64 bytenr)
725 {
726 	return block_group_cache_tree_search(info, bytenr, 0);
727 }
728 
729 /*
730  * return the block group that contains the given bytenr
731  */
732 struct btrfs_block_group_cache *btrfs_lookup_block_group(
733 						 struct btrfs_fs_info *info,
734 						 u64 bytenr)
735 {
736 	return block_group_cache_tree_search(info, bytenr, 1);
737 }
738 
739 static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
740 						  u64 flags)
741 {
742 	struct list_head *head = &info->space_info;
743 	struct btrfs_space_info *found;
744 
745 	flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
746 
747 	rcu_read_lock();
748 	list_for_each_entry_rcu(found, head, list) {
749 		if (found->flags & flags) {
750 			rcu_read_unlock();
751 			return found;
752 		}
753 	}
754 	rcu_read_unlock();
755 	return NULL;
756 }
757 
758 /*
759  * after adding space to the filesystem, we need to clear the full flags
760  * on all the space infos.
761  */
762 void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
763 {
764 	struct list_head *head = &info->space_info;
765 	struct btrfs_space_info *found;
766 
767 	rcu_read_lock();
768 	list_for_each_entry_rcu(found, head, list)
769 		found->full = 0;
770 	rcu_read_unlock();
771 }
772 
773 /* simple helper to search for an existing data extent at a given offset */
774 int btrfs_lookup_data_extent(struct btrfs_fs_info *fs_info, u64 start, u64 len)
775 {
776 	int ret;
777 	struct btrfs_key key;
778 	struct btrfs_path *path;
779 
780 	path = btrfs_alloc_path();
781 	if (!path)
782 		return -ENOMEM;
783 
784 	key.objectid = start;
785 	key.offset = len;
786 	key.type = BTRFS_EXTENT_ITEM_KEY;
787 	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
788 	btrfs_free_path(path);
789 	return ret;
790 }
791 
792 /*
793  * helper function to lookup reference count and flags of a tree block.
794  *
795  * the head node for delayed ref is used to store the sum of all the
796  * reference count modifications queued up in the rbtree. the head
797  * node may also store the extent flags to set. This way you can check
798  * to see what the reference count and extent flags would be if all of
799  * the delayed refs are not processed.
800  */
801 int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
802 			     struct btrfs_fs_info *fs_info, u64 bytenr,
803 			     u64 offset, int metadata, u64 *refs, u64 *flags)
804 {
805 	struct btrfs_delayed_ref_head *head;
806 	struct btrfs_delayed_ref_root *delayed_refs;
807 	struct btrfs_path *path;
808 	struct btrfs_extent_item *ei;
809 	struct extent_buffer *leaf;
810 	struct btrfs_key key;
811 	u32 item_size;
812 	u64 num_refs;
813 	u64 extent_flags;
814 	int ret;
815 
816 	/*
817 	 * If we don't have skinny metadata, don't bother doing anything
818 	 * different
819 	 */
820 	if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA)) {
821 		offset = fs_info->nodesize;
822 		metadata = 0;
823 	}
824 
825 	path = btrfs_alloc_path();
826 	if (!path)
827 		return -ENOMEM;
828 
829 	if (!trans) {
830 		path->skip_locking = 1;
831 		path->search_commit_root = 1;
832 	}
833 
834 search_again:
835 	key.objectid = bytenr;
836 	key.offset = offset;
837 	if (metadata)
838 		key.type = BTRFS_METADATA_ITEM_KEY;
839 	else
840 		key.type = BTRFS_EXTENT_ITEM_KEY;
841 
842 	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
843 	if (ret < 0)
844 		goto out_free;
845 
846 	if (ret > 0 && metadata && key.type == BTRFS_METADATA_ITEM_KEY) {
847 		if (path->slots[0]) {
848 			path->slots[0]--;
849 			btrfs_item_key_to_cpu(path->nodes[0], &key,
850 					      path->slots[0]);
851 			if (key.objectid == bytenr &&
852 			    key.type == BTRFS_EXTENT_ITEM_KEY &&
853 			    key.offset == fs_info->nodesize)
854 				ret = 0;
855 		}
856 	}
857 
858 	if (ret == 0) {
859 		leaf = path->nodes[0];
860 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
861 		if (item_size >= sizeof(*ei)) {
862 			ei = btrfs_item_ptr(leaf, path->slots[0],
863 					    struct btrfs_extent_item);
864 			num_refs = btrfs_extent_refs(leaf, ei);
865 			extent_flags = btrfs_extent_flags(leaf, ei);
866 		} else {
867 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
868 			struct btrfs_extent_item_v0 *ei0;
869 			BUG_ON(item_size != sizeof(*ei0));
870 			ei0 = btrfs_item_ptr(leaf, path->slots[0],
871 					     struct btrfs_extent_item_v0);
872 			num_refs = btrfs_extent_refs_v0(leaf, ei0);
873 			/* FIXME: this isn't correct for data */
874 			extent_flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
875 #else
876 			BUG();
877 #endif
878 		}
879 		BUG_ON(num_refs == 0);
880 	} else {
881 		num_refs = 0;
882 		extent_flags = 0;
883 		ret = 0;
884 	}
885 
886 	if (!trans)
887 		goto out;
888 
889 	delayed_refs = &trans->transaction->delayed_refs;
890 	spin_lock(&delayed_refs->lock);
891 	head = btrfs_find_delayed_ref_head(trans, bytenr);
892 	if (head) {
893 		if (!mutex_trylock(&head->mutex)) {
894 			atomic_inc(&head->node.refs);
895 			spin_unlock(&delayed_refs->lock);
896 
897 			btrfs_release_path(path);
898 
899 			/*
900 			 * Mutex was contended, block until it's released and try
901 			 * again
902 			 */
903 			mutex_lock(&head->mutex);
904 			mutex_unlock(&head->mutex);
905 			btrfs_put_delayed_ref(&head->node);
906 			goto search_again;
907 		}
908 		spin_lock(&head->lock);
909 		if (head->extent_op && head->extent_op->update_flags)
910 			extent_flags |= head->extent_op->flags_to_set;
911 		else
912 			BUG_ON(num_refs == 0);
913 
914 		num_refs += head->node.ref_mod;
915 		spin_unlock(&head->lock);
916 		mutex_unlock(&head->mutex);
917 	}
918 	spin_unlock(&delayed_refs->lock);
919 out:
920 	WARN_ON(num_refs == 0);
921 	if (refs)
922 		*refs = num_refs;
923 	if (flags)
924 		*flags = extent_flags;
925 out_free:
926 	btrfs_free_path(path);
927 	return ret;
928 }
929 
930 /*
931  * Back reference rules.  Back refs have three main goals:
932  *
933  * 1) differentiate between all holders of references to an extent so that
934  *    when a reference is dropped we can make sure it was a valid reference
935  *    before freeing the extent.
936  *
937  * 2) Provide enough information to quickly find the holders of an extent
938  *    if we notice a given block is corrupted or bad.
939  *
940  * 3) Make it easy to migrate blocks for FS shrinking or storage pool
941  *    maintenance.  This is actually the same as #2, but with a slightly
942  *    different use case.
943  *
944  * There are two kinds of back refs. The implicit back refs is optimized
945  * for pointers in non-shared tree blocks. For a given pointer in a block,
946  * back refs of this kind provide information about the block's owner tree
947  * and the pointer's key. These information allow us to find the block by
948  * b-tree searching. The full back refs is for pointers in tree blocks not
949  * referenced by their owner trees. The location of tree block is recorded
950  * in the back refs. Actually the full back refs is generic, and can be
951  * used in all cases the implicit back refs is used. The major shortcoming
952  * of the full back refs is its overhead. Every time a tree block gets
953  * COWed, we have to update back refs entry for all pointers in it.
954  *
955  * For a newly allocated tree block, we use implicit back refs for
956  * pointers in it. This means most tree related operations only involve
957  * implicit back refs. For a tree block created in old transaction, the
958  * only way to drop a reference to it is COW it. So we can detect the
959  * event that tree block loses its owner tree's reference and do the
960  * back refs conversion.
961  *
962  * When a tree block is COWed through a tree, there are four cases:
963  *
964  * The reference count of the block is one and the tree is the block's
965  * owner tree. Nothing to do in this case.
966  *
967  * The reference count of the block is one and the tree is not the
968  * block's owner tree. In this case, full back refs is used for pointers
969  * in the block. Remove these full back refs, add implicit back refs for
970  * every pointers in the new block.
971  *
972  * The reference count of the block is greater than one and the tree is
973  * the block's owner tree. In this case, implicit back refs is used for
974  * pointers in the block. Add full back refs for every pointers in the
975  * block, increase lower level extents' reference counts. The original
976  * implicit back refs are entailed to the new block.
977  *
978  * The reference count of the block is greater than one and the tree is
979  * not the block's owner tree. Add implicit back refs for every pointer in
980  * the new block, increase lower level extents' reference count.
981  *
982  * Back Reference Key composing:
983  *
984  * The key objectid corresponds to the first byte in the extent,
985  * The key type is used to differentiate between types of back refs.
986  * There are different meanings of the key offset for different types
987  * of back refs.
988  *
989  * File extents can be referenced by:
990  *
991  * - multiple snapshots, subvolumes, or different generations in one subvol
992  * - different files inside a single subvolume
993  * - different offsets inside a file (bookend extents in file.c)
994  *
995  * The extent ref structure for the implicit back refs has fields for:
996  *
997  * - Objectid of the subvolume root
998  * - objectid of the file holding the reference
999  * - original offset in the file
1000  * - how many bookend extents
1001  *
1002  * The key offset for the implicit back refs is hash of the first
1003  * three fields.
1004  *
1005  * The extent ref structure for the full back refs has field for:
1006  *
1007  * - number of pointers in the tree leaf
1008  *
1009  * The key offset for the implicit back refs is the first byte of
1010  * the tree leaf
1011  *
1012  * When a file extent is allocated, The implicit back refs is used.
1013  * the fields are filled in:
1014  *
1015  *     (root_key.objectid, inode objectid, offset in file, 1)
1016  *
1017  * When a file extent is removed file truncation, we find the
1018  * corresponding implicit back refs and check the following fields:
1019  *
1020  *     (btrfs_header_owner(leaf), inode objectid, offset in file)
1021  *
1022  * Btree extents can be referenced by:
1023  *
1024  * - Different subvolumes
1025  *
1026  * Both the implicit back refs and the full back refs for tree blocks
1027  * only consist of key. The key offset for the implicit back refs is
1028  * objectid of block's owner tree. The key offset for the full back refs
1029  * is the first byte of parent block.
1030  *
1031  * When implicit back refs is used, information about the lowest key and
1032  * level of the tree block are required. These information are stored in
1033  * tree block info structure.
1034  */
1035 
1036 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1037 static int convert_extent_item_v0(struct btrfs_trans_handle *trans,
1038 				  struct btrfs_root *root,
1039 				  struct btrfs_path *path,
1040 				  u64 owner, u32 extra_size)
1041 {
1042 	struct btrfs_extent_item *item;
1043 	struct btrfs_extent_item_v0 *ei0;
1044 	struct btrfs_extent_ref_v0 *ref0;
1045 	struct btrfs_tree_block_info *bi;
1046 	struct extent_buffer *leaf;
1047 	struct btrfs_key key;
1048 	struct btrfs_key found_key;
1049 	u32 new_size = sizeof(*item);
1050 	u64 refs;
1051 	int ret;
1052 
1053 	leaf = path->nodes[0];
1054 	BUG_ON(btrfs_item_size_nr(leaf, path->slots[0]) != sizeof(*ei0));
1055 
1056 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1057 	ei0 = btrfs_item_ptr(leaf, path->slots[0],
1058 			     struct btrfs_extent_item_v0);
1059 	refs = btrfs_extent_refs_v0(leaf, ei0);
1060 
1061 	if (owner == (u64)-1) {
1062 		while (1) {
1063 			if (path->slots[0] >= btrfs_header_nritems(leaf)) {
1064 				ret = btrfs_next_leaf(root, path);
1065 				if (ret < 0)
1066 					return ret;
1067 				BUG_ON(ret > 0); /* Corruption */
1068 				leaf = path->nodes[0];
1069 			}
1070 			btrfs_item_key_to_cpu(leaf, &found_key,
1071 					      path->slots[0]);
1072 			BUG_ON(key.objectid != found_key.objectid);
1073 			if (found_key.type != BTRFS_EXTENT_REF_V0_KEY) {
1074 				path->slots[0]++;
1075 				continue;
1076 			}
1077 			ref0 = btrfs_item_ptr(leaf, path->slots[0],
1078 					      struct btrfs_extent_ref_v0);
1079 			owner = btrfs_ref_objectid_v0(leaf, ref0);
1080 			break;
1081 		}
1082 	}
1083 	btrfs_release_path(path);
1084 
1085 	if (owner < BTRFS_FIRST_FREE_OBJECTID)
1086 		new_size += sizeof(*bi);
1087 
1088 	new_size -= sizeof(*ei0);
1089 	ret = btrfs_search_slot(trans, root, &key, path,
1090 				new_size + extra_size, 1);
1091 	if (ret < 0)
1092 		return ret;
1093 	BUG_ON(ret); /* Corruption */
1094 
1095 	btrfs_extend_item(root->fs_info, path, new_size);
1096 
1097 	leaf = path->nodes[0];
1098 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1099 	btrfs_set_extent_refs(leaf, item, refs);
1100 	/* FIXME: get real generation */
1101 	btrfs_set_extent_generation(leaf, item, 0);
1102 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1103 		btrfs_set_extent_flags(leaf, item,
1104 				       BTRFS_EXTENT_FLAG_TREE_BLOCK |
1105 				       BTRFS_BLOCK_FLAG_FULL_BACKREF);
1106 		bi = (struct btrfs_tree_block_info *)(item + 1);
1107 		/* FIXME: get first key of the block */
1108 		memzero_extent_buffer(leaf, (unsigned long)bi, sizeof(*bi));
1109 		btrfs_set_tree_block_level(leaf, bi, (int)owner);
1110 	} else {
1111 		btrfs_set_extent_flags(leaf, item, BTRFS_EXTENT_FLAG_DATA);
1112 	}
1113 	btrfs_mark_buffer_dirty(leaf);
1114 	return 0;
1115 }
1116 #endif
1117 
1118 static u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset)
1119 {
1120 	u32 high_crc = ~(u32)0;
1121 	u32 low_crc = ~(u32)0;
1122 	__le64 lenum;
1123 
1124 	lenum = cpu_to_le64(root_objectid);
1125 	high_crc = btrfs_crc32c(high_crc, &lenum, sizeof(lenum));
1126 	lenum = cpu_to_le64(owner);
1127 	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
1128 	lenum = cpu_to_le64(offset);
1129 	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
1130 
1131 	return ((u64)high_crc << 31) ^ (u64)low_crc;
1132 }
1133 
1134 static u64 hash_extent_data_ref_item(struct extent_buffer *leaf,
1135 				     struct btrfs_extent_data_ref *ref)
1136 {
1137 	return hash_extent_data_ref(btrfs_extent_data_ref_root(leaf, ref),
1138 				    btrfs_extent_data_ref_objectid(leaf, ref),
1139 				    btrfs_extent_data_ref_offset(leaf, ref));
1140 }
1141 
1142 static int match_extent_data_ref(struct extent_buffer *leaf,
1143 				 struct btrfs_extent_data_ref *ref,
1144 				 u64 root_objectid, u64 owner, u64 offset)
1145 {
1146 	if (btrfs_extent_data_ref_root(leaf, ref) != root_objectid ||
1147 	    btrfs_extent_data_ref_objectid(leaf, ref) != owner ||
1148 	    btrfs_extent_data_ref_offset(leaf, ref) != offset)
1149 		return 0;
1150 	return 1;
1151 }
1152 
1153 static noinline int lookup_extent_data_ref(struct btrfs_trans_handle *trans,
1154 					   struct btrfs_root *root,
1155 					   struct btrfs_path *path,
1156 					   u64 bytenr, u64 parent,
1157 					   u64 root_objectid,
1158 					   u64 owner, u64 offset)
1159 {
1160 	struct btrfs_key key;
1161 	struct btrfs_extent_data_ref *ref;
1162 	struct extent_buffer *leaf;
1163 	u32 nritems;
1164 	int ret;
1165 	int recow;
1166 	int err = -ENOENT;
1167 
1168 	key.objectid = bytenr;
1169 	if (parent) {
1170 		key.type = BTRFS_SHARED_DATA_REF_KEY;
1171 		key.offset = parent;
1172 	} else {
1173 		key.type = BTRFS_EXTENT_DATA_REF_KEY;
1174 		key.offset = hash_extent_data_ref(root_objectid,
1175 						  owner, offset);
1176 	}
1177 again:
1178 	recow = 0;
1179 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1180 	if (ret < 0) {
1181 		err = ret;
1182 		goto fail;
1183 	}
1184 
1185 	if (parent) {
1186 		if (!ret)
1187 			return 0;
1188 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1189 		key.type = BTRFS_EXTENT_REF_V0_KEY;
1190 		btrfs_release_path(path);
1191 		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1192 		if (ret < 0) {
1193 			err = ret;
1194 			goto fail;
1195 		}
1196 		if (!ret)
1197 			return 0;
1198 #endif
1199 		goto fail;
1200 	}
1201 
1202 	leaf = path->nodes[0];
1203 	nritems = btrfs_header_nritems(leaf);
1204 	while (1) {
1205 		if (path->slots[0] >= nritems) {
1206 			ret = btrfs_next_leaf(root, path);
1207 			if (ret < 0)
1208 				err = ret;
1209 			if (ret)
1210 				goto fail;
1211 
1212 			leaf = path->nodes[0];
1213 			nritems = btrfs_header_nritems(leaf);
1214 			recow = 1;
1215 		}
1216 
1217 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1218 		if (key.objectid != bytenr ||
1219 		    key.type != BTRFS_EXTENT_DATA_REF_KEY)
1220 			goto fail;
1221 
1222 		ref = btrfs_item_ptr(leaf, path->slots[0],
1223 				     struct btrfs_extent_data_ref);
1224 
1225 		if (match_extent_data_ref(leaf, ref, root_objectid,
1226 					  owner, offset)) {
1227 			if (recow) {
1228 				btrfs_release_path(path);
1229 				goto again;
1230 			}
1231 			err = 0;
1232 			break;
1233 		}
1234 		path->slots[0]++;
1235 	}
1236 fail:
1237 	return err;
1238 }
1239 
1240 static noinline int insert_extent_data_ref(struct btrfs_trans_handle *trans,
1241 					   struct btrfs_root *root,
1242 					   struct btrfs_path *path,
1243 					   u64 bytenr, u64 parent,
1244 					   u64 root_objectid, u64 owner,
1245 					   u64 offset, int refs_to_add)
1246 {
1247 	struct btrfs_key key;
1248 	struct extent_buffer *leaf;
1249 	u32 size;
1250 	u32 num_refs;
1251 	int ret;
1252 
1253 	key.objectid = bytenr;
1254 	if (parent) {
1255 		key.type = BTRFS_SHARED_DATA_REF_KEY;
1256 		key.offset = parent;
1257 		size = sizeof(struct btrfs_shared_data_ref);
1258 	} else {
1259 		key.type = BTRFS_EXTENT_DATA_REF_KEY;
1260 		key.offset = hash_extent_data_ref(root_objectid,
1261 						  owner, offset);
1262 		size = sizeof(struct btrfs_extent_data_ref);
1263 	}
1264 
1265 	ret = btrfs_insert_empty_item(trans, root, path, &key, size);
1266 	if (ret && ret != -EEXIST)
1267 		goto fail;
1268 
1269 	leaf = path->nodes[0];
1270 	if (parent) {
1271 		struct btrfs_shared_data_ref *ref;
1272 		ref = btrfs_item_ptr(leaf, path->slots[0],
1273 				     struct btrfs_shared_data_ref);
1274 		if (ret == 0) {
1275 			btrfs_set_shared_data_ref_count(leaf, ref, refs_to_add);
1276 		} else {
1277 			num_refs = btrfs_shared_data_ref_count(leaf, ref);
1278 			num_refs += refs_to_add;
1279 			btrfs_set_shared_data_ref_count(leaf, ref, num_refs);
1280 		}
1281 	} else {
1282 		struct btrfs_extent_data_ref *ref;
1283 		while (ret == -EEXIST) {
1284 			ref = btrfs_item_ptr(leaf, path->slots[0],
1285 					     struct btrfs_extent_data_ref);
1286 			if (match_extent_data_ref(leaf, ref, root_objectid,
1287 						  owner, offset))
1288 				break;
1289 			btrfs_release_path(path);
1290 			key.offset++;
1291 			ret = btrfs_insert_empty_item(trans, root, path, &key,
1292 						      size);
1293 			if (ret && ret != -EEXIST)
1294 				goto fail;
1295 
1296 			leaf = path->nodes[0];
1297 		}
1298 		ref = btrfs_item_ptr(leaf, path->slots[0],
1299 				     struct btrfs_extent_data_ref);
1300 		if (ret == 0) {
1301 			btrfs_set_extent_data_ref_root(leaf, ref,
1302 						       root_objectid);
1303 			btrfs_set_extent_data_ref_objectid(leaf, ref, owner);
1304 			btrfs_set_extent_data_ref_offset(leaf, ref, offset);
1305 			btrfs_set_extent_data_ref_count(leaf, ref, refs_to_add);
1306 		} else {
1307 			num_refs = btrfs_extent_data_ref_count(leaf, ref);
1308 			num_refs += refs_to_add;
1309 			btrfs_set_extent_data_ref_count(leaf, ref, num_refs);
1310 		}
1311 	}
1312 	btrfs_mark_buffer_dirty(leaf);
1313 	ret = 0;
1314 fail:
1315 	btrfs_release_path(path);
1316 	return ret;
1317 }
1318 
1319 static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
1320 					   struct btrfs_root *root,
1321 					   struct btrfs_path *path,
1322 					   int refs_to_drop, int *last_ref)
1323 {
1324 	struct btrfs_key key;
1325 	struct btrfs_extent_data_ref *ref1 = NULL;
1326 	struct btrfs_shared_data_ref *ref2 = NULL;
1327 	struct extent_buffer *leaf;
1328 	u32 num_refs = 0;
1329 	int ret = 0;
1330 
1331 	leaf = path->nodes[0];
1332 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1333 
1334 	if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
1335 		ref1 = btrfs_item_ptr(leaf, path->slots[0],
1336 				      struct btrfs_extent_data_ref);
1337 		num_refs = btrfs_extent_data_ref_count(leaf, ref1);
1338 	} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
1339 		ref2 = btrfs_item_ptr(leaf, path->slots[0],
1340 				      struct btrfs_shared_data_ref);
1341 		num_refs = btrfs_shared_data_ref_count(leaf, ref2);
1342 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1343 	} else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
1344 		struct btrfs_extent_ref_v0 *ref0;
1345 		ref0 = btrfs_item_ptr(leaf, path->slots[0],
1346 				      struct btrfs_extent_ref_v0);
1347 		num_refs = btrfs_ref_count_v0(leaf, ref0);
1348 #endif
1349 	} else {
1350 		BUG();
1351 	}
1352 
1353 	BUG_ON(num_refs < refs_to_drop);
1354 	num_refs -= refs_to_drop;
1355 
1356 	if (num_refs == 0) {
1357 		ret = btrfs_del_item(trans, root, path);
1358 		*last_ref = 1;
1359 	} else {
1360 		if (key.type == BTRFS_EXTENT_DATA_REF_KEY)
1361 			btrfs_set_extent_data_ref_count(leaf, ref1, num_refs);
1362 		else if (key.type == BTRFS_SHARED_DATA_REF_KEY)
1363 			btrfs_set_shared_data_ref_count(leaf, ref2, num_refs);
1364 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1365 		else {
1366 			struct btrfs_extent_ref_v0 *ref0;
1367 			ref0 = btrfs_item_ptr(leaf, path->slots[0],
1368 					struct btrfs_extent_ref_v0);
1369 			btrfs_set_ref_count_v0(leaf, ref0, num_refs);
1370 		}
1371 #endif
1372 		btrfs_mark_buffer_dirty(leaf);
1373 	}
1374 	return ret;
1375 }
1376 
1377 static noinline u32 extent_data_ref_count(struct btrfs_path *path,
1378 					  struct btrfs_extent_inline_ref *iref)
1379 {
1380 	struct btrfs_key key;
1381 	struct extent_buffer *leaf;
1382 	struct btrfs_extent_data_ref *ref1;
1383 	struct btrfs_shared_data_ref *ref2;
1384 	u32 num_refs = 0;
1385 
1386 	leaf = path->nodes[0];
1387 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1388 	if (iref) {
1389 		if (btrfs_extent_inline_ref_type(leaf, iref) ==
1390 		    BTRFS_EXTENT_DATA_REF_KEY) {
1391 			ref1 = (struct btrfs_extent_data_ref *)(&iref->offset);
1392 			num_refs = btrfs_extent_data_ref_count(leaf, ref1);
1393 		} else {
1394 			ref2 = (struct btrfs_shared_data_ref *)(iref + 1);
1395 			num_refs = btrfs_shared_data_ref_count(leaf, ref2);
1396 		}
1397 	} else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
1398 		ref1 = btrfs_item_ptr(leaf, path->slots[0],
1399 				      struct btrfs_extent_data_ref);
1400 		num_refs = btrfs_extent_data_ref_count(leaf, ref1);
1401 	} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
1402 		ref2 = btrfs_item_ptr(leaf, path->slots[0],
1403 				      struct btrfs_shared_data_ref);
1404 		num_refs = btrfs_shared_data_ref_count(leaf, ref2);
1405 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1406 	} else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
1407 		struct btrfs_extent_ref_v0 *ref0;
1408 		ref0 = btrfs_item_ptr(leaf, path->slots[0],
1409 				      struct btrfs_extent_ref_v0);
1410 		num_refs = btrfs_ref_count_v0(leaf, ref0);
1411 #endif
1412 	} else {
1413 		WARN_ON(1);
1414 	}
1415 	return num_refs;
1416 }
1417 
1418 static noinline int lookup_tree_block_ref(struct btrfs_trans_handle *trans,
1419 					  struct btrfs_root *root,
1420 					  struct btrfs_path *path,
1421 					  u64 bytenr, u64 parent,
1422 					  u64 root_objectid)
1423 {
1424 	struct btrfs_key key;
1425 	int ret;
1426 
1427 	key.objectid = bytenr;
1428 	if (parent) {
1429 		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
1430 		key.offset = parent;
1431 	} else {
1432 		key.type = BTRFS_TREE_BLOCK_REF_KEY;
1433 		key.offset = root_objectid;
1434 	}
1435 
1436 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1437 	if (ret > 0)
1438 		ret = -ENOENT;
1439 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1440 	if (ret == -ENOENT && parent) {
1441 		btrfs_release_path(path);
1442 		key.type = BTRFS_EXTENT_REF_V0_KEY;
1443 		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1444 		if (ret > 0)
1445 			ret = -ENOENT;
1446 	}
1447 #endif
1448 	return ret;
1449 }
1450 
1451 static noinline int insert_tree_block_ref(struct btrfs_trans_handle *trans,
1452 					  struct btrfs_root *root,
1453 					  struct btrfs_path *path,
1454 					  u64 bytenr, u64 parent,
1455 					  u64 root_objectid)
1456 {
1457 	struct btrfs_key key;
1458 	int ret;
1459 
1460 	key.objectid = bytenr;
1461 	if (parent) {
1462 		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
1463 		key.offset = parent;
1464 	} else {
1465 		key.type = BTRFS_TREE_BLOCK_REF_KEY;
1466 		key.offset = root_objectid;
1467 	}
1468 
1469 	ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
1470 	btrfs_release_path(path);
1471 	return ret;
1472 }
1473 
1474 static inline int extent_ref_type(u64 parent, u64 owner)
1475 {
1476 	int type;
1477 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1478 		if (parent > 0)
1479 			type = BTRFS_SHARED_BLOCK_REF_KEY;
1480 		else
1481 			type = BTRFS_TREE_BLOCK_REF_KEY;
1482 	} else {
1483 		if (parent > 0)
1484 			type = BTRFS_SHARED_DATA_REF_KEY;
1485 		else
1486 			type = BTRFS_EXTENT_DATA_REF_KEY;
1487 	}
1488 	return type;
1489 }
1490 
1491 static int find_next_key(struct btrfs_path *path, int level,
1492 			 struct btrfs_key *key)
1493 
1494 {
1495 	for (; level < BTRFS_MAX_LEVEL; level++) {
1496 		if (!path->nodes[level])
1497 			break;
1498 		if (path->slots[level] + 1 >=
1499 		    btrfs_header_nritems(path->nodes[level]))
1500 			continue;
1501 		if (level == 0)
1502 			btrfs_item_key_to_cpu(path->nodes[level], key,
1503 					      path->slots[level] + 1);
1504 		else
1505 			btrfs_node_key_to_cpu(path->nodes[level], key,
1506 					      path->slots[level] + 1);
1507 		return 0;
1508 	}
1509 	return 1;
1510 }
1511 
1512 /*
1513  * look for inline back ref. if back ref is found, *ref_ret is set
1514  * to the address of inline back ref, and 0 is returned.
1515  *
1516  * if back ref isn't found, *ref_ret is set to the address where it
1517  * should be inserted, and -ENOENT is returned.
1518  *
1519  * if insert is true and there are too many inline back refs, the path
1520  * points to the extent item, and -EAGAIN is returned.
1521  *
1522  * NOTE: inline back refs are ordered in the same way that back ref
1523  *	 items in the tree are ordered.
1524  */
1525 static noinline_for_stack
1526 int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
1527 				 struct btrfs_root *root,
1528 				 struct btrfs_path *path,
1529 				 struct btrfs_extent_inline_ref **ref_ret,
1530 				 u64 bytenr, u64 num_bytes,
1531 				 u64 parent, u64 root_objectid,
1532 				 u64 owner, u64 offset, int insert)
1533 {
1534 	struct btrfs_fs_info *fs_info = root->fs_info;
1535 	struct btrfs_key key;
1536 	struct extent_buffer *leaf;
1537 	struct btrfs_extent_item *ei;
1538 	struct btrfs_extent_inline_ref *iref;
1539 	u64 flags;
1540 	u64 item_size;
1541 	unsigned long ptr;
1542 	unsigned long end;
1543 	int extra_size;
1544 	int type;
1545 	int want;
1546 	int ret;
1547 	int err = 0;
1548 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
1549 
1550 	key.objectid = bytenr;
1551 	key.type = BTRFS_EXTENT_ITEM_KEY;
1552 	key.offset = num_bytes;
1553 
1554 	want = extent_ref_type(parent, owner);
1555 	if (insert) {
1556 		extra_size = btrfs_extent_inline_ref_size(want);
1557 		path->keep_locks = 1;
1558 	} else
1559 		extra_size = -1;
1560 
1561 	/*
1562 	 * Owner is our parent level, so we can just add one to get the level
1563 	 * for the block we are interested in.
1564 	 */
1565 	if (skinny_metadata && owner < BTRFS_FIRST_FREE_OBJECTID) {
1566 		key.type = BTRFS_METADATA_ITEM_KEY;
1567 		key.offset = owner;
1568 	}
1569 
1570 again:
1571 	ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
1572 	if (ret < 0) {
1573 		err = ret;
1574 		goto out;
1575 	}
1576 
1577 	/*
1578 	 * We may be a newly converted file system which still has the old fat
1579 	 * extent entries for metadata, so try and see if we have one of those.
1580 	 */
1581 	if (ret > 0 && skinny_metadata) {
1582 		skinny_metadata = false;
1583 		if (path->slots[0]) {
1584 			path->slots[0]--;
1585 			btrfs_item_key_to_cpu(path->nodes[0], &key,
1586 					      path->slots[0]);
1587 			if (key.objectid == bytenr &&
1588 			    key.type == BTRFS_EXTENT_ITEM_KEY &&
1589 			    key.offset == num_bytes)
1590 				ret = 0;
1591 		}
1592 		if (ret) {
1593 			key.objectid = bytenr;
1594 			key.type = BTRFS_EXTENT_ITEM_KEY;
1595 			key.offset = num_bytes;
1596 			btrfs_release_path(path);
1597 			goto again;
1598 		}
1599 	}
1600 
1601 	if (ret && !insert) {
1602 		err = -ENOENT;
1603 		goto out;
1604 	} else if (WARN_ON(ret)) {
1605 		err = -EIO;
1606 		goto out;
1607 	}
1608 
1609 	leaf = path->nodes[0];
1610 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1611 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1612 	if (item_size < sizeof(*ei)) {
1613 		if (!insert) {
1614 			err = -ENOENT;
1615 			goto out;
1616 		}
1617 		ret = convert_extent_item_v0(trans, root, path, owner,
1618 					     extra_size);
1619 		if (ret < 0) {
1620 			err = ret;
1621 			goto out;
1622 		}
1623 		leaf = path->nodes[0];
1624 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1625 	}
1626 #endif
1627 	BUG_ON(item_size < sizeof(*ei));
1628 
1629 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1630 	flags = btrfs_extent_flags(leaf, ei);
1631 
1632 	ptr = (unsigned long)(ei + 1);
1633 	end = (unsigned long)ei + item_size;
1634 
1635 	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK && !skinny_metadata) {
1636 		ptr += sizeof(struct btrfs_tree_block_info);
1637 		BUG_ON(ptr > end);
1638 	}
1639 
1640 	err = -ENOENT;
1641 	while (1) {
1642 		if (ptr >= end) {
1643 			WARN_ON(ptr > end);
1644 			break;
1645 		}
1646 		iref = (struct btrfs_extent_inline_ref *)ptr;
1647 		type = btrfs_extent_inline_ref_type(leaf, iref);
1648 		if (want < type)
1649 			break;
1650 		if (want > type) {
1651 			ptr += btrfs_extent_inline_ref_size(type);
1652 			continue;
1653 		}
1654 
1655 		if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1656 			struct btrfs_extent_data_ref *dref;
1657 			dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1658 			if (match_extent_data_ref(leaf, dref, root_objectid,
1659 						  owner, offset)) {
1660 				err = 0;
1661 				break;
1662 			}
1663 			if (hash_extent_data_ref_item(leaf, dref) <
1664 			    hash_extent_data_ref(root_objectid, owner, offset))
1665 				break;
1666 		} else {
1667 			u64 ref_offset;
1668 			ref_offset = btrfs_extent_inline_ref_offset(leaf, iref);
1669 			if (parent > 0) {
1670 				if (parent == ref_offset) {
1671 					err = 0;
1672 					break;
1673 				}
1674 				if (ref_offset < parent)
1675 					break;
1676 			} else {
1677 				if (root_objectid == ref_offset) {
1678 					err = 0;
1679 					break;
1680 				}
1681 				if (ref_offset < root_objectid)
1682 					break;
1683 			}
1684 		}
1685 		ptr += btrfs_extent_inline_ref_size(type);
1686 	}
1687 	if (err == -ENOENT && insert) {
1688 		if (item_size + extra_size >=
1689 		    BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
1690 			err = -EAGAIN;
1691 			goto out;
1692 		}
1693 		/*
1694 		 * To add new inline back ref, we have to make sure
1695 		 * there is no corresponding back ref item.
1696 		 * For simplicity, we just do not add new inline back
1697 		 * ref if there is any kind of item for this block
1698 		 */
1699 		if (find_next_key(path, 0, &key) == 0 &&
1700 		    key.objectid == bytenr &&
1701 		    key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
1702 			err = -EAGAIN;
1703 			goto out;
1704 		}
1705 	}
1706 	*ref_ret = (struct btrfs_extent_inline_ref *)ptr;
1707 out:
1708 	if (insert) {
1709 		path->keep_locks = 0;
1710 		btrfs_unlock_up_safe(path, 1);
1711 	}
1712 	return err;
1713 }
1714 
1715 /*
1716  * helper to add new inline back ref
1717  */
1718 static noinline_for_stack
1719 void setup_inline_extent_backref(struct btrfs_root *root,
1720 				 struct btrfs_path *path,
1721 				 struct btrfs_extent_inline_ref *iref,
1722 				 u64 parent, u64 root_objectid,
1723 				 u64 owner, u64 offset, int refs_to_add,
1724 				 struct btrfs_delayed_extent_op *extent_op)
1725 {
1726 	struct extent_buffer *leaf;
1727 	struct btrfs_extent_item *ei;
1728 	unsigned long ptr;
1729 	unsigned long end;
1730 	unsigned long item_offset;
1731 	u64 refs;
1732 	int size;
1733 	int type;
1734 
1735 	leaf = path->nodes[0];
1736 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1737 	item_offset = (unsigned long)iref - (unsigned long)ei;
1738 
1739 	type = extent_ref_type(parent, owner);
1740 	size = btrfs_extent_inline_ref_size(type);
1741 
1742 	btrfs_extend_item(root->fs_info, path, size);
1743 
1744 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1745 	refs = btrfs_extent_refs(leaf, ei);
1746 	refs += refs_to_add;
1747 	btrfs_set_extent_refs(leaf, ei, refs);
1748 	if (extent_op)
1749 		__run_delayed_extent_op(extent_op, leaf, ei);
1750 
1751 	ptr = (unsigned long)ei + item_offset;
1752 	end = (unsigned long)ei + btrfs_item_size_nr(leaf, path->slots[0]);
1753 	if (ptr < end - size)
1754 		memmove_extent_buffer(leaf, ptr + size, ptr,
1755 				      end - size - ptr);
1756 
1757 	iref = (struct btrfs_extent_inline_ref *)ptr;
1758 	btrfs_set_extent_inline_ref_type(leaf, iref, type);
1759 	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1760 		struct btrfs_extent_data_ref *dref;
1761 		dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1762 		btrfs_set_extent_data_ref_root(leaf, dref, root_objectid);
1763 		btrfs_set_extent_data_ref_objectid(leaf, dref, owner);
1764 		btrfs_set_extent_data_ref_offset(leaf, dref, offset);
1765 		btrfs_set_extent_data_ref_count(leaf, dref, refs_to_add);
1766 	} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1767 		struct btrfs_shared_data_ref *sref;
1768 		sref = (struct btrfs_shared_data_ref *)(iref + 1);
1769 		btrfs_set_shared_data_ref_count(leaf, sref, refs_to_add);
1770 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
1771 	} else if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
1772 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
1773 	} else {
1774 		btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
1775 	}
1776 	btrfs_mark_buffer_dirty(leaf);
1777 }
1778 
1779 static int lookup_extent_backref(struct btrfs_trans_handle *trans,
1780 				 struct btrfs_root *root,
1781 				 struct btrfs_path *path,
1782 				 struct btrfs_extent_inline_ref **ref_ret,
1783 				 u64 bytenr, u64 num_bytes, u64 parent,
1784 				 u64 root_objectid, u64 owner, u64 offset)
1785 {
1786 	int ret;
1787 
1788 	ret = lookup_inline_extent_backref(trans, root, path, ref_ret,
1789 					   bytenr, num_bytes, parent,
1790 					   root_objectid, owner, offset, 0);
1791 	if (ret != -ENOENT)
1792 		return ret;
1793 
1794 	btrfs_release_path(path);
1795 	*ref_ret = NULL;
1796 
1797 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1798 		ret = lookup_tree_block_ref(trans, root, path, bytenr, parent,
1799 					    root_objectid);
1800 	} else {
1801 		ret = lookup_extent_data_ref(trans, root, path, bytenr, parent,
1802 					     root_objectid, owner, offset);
1803 	}
1804 	return ret;
1805 }
1806 
1807 /*
1808  * helper to update/remove inline back ref
1809  */
1810 static noinline_for_stack
1811 void update_inline_extent_backref(struct btrfs_root *root,
1812 				  struct btrfs_path *path,
1813 				  struct btrfs_extent_inline_ref *iref,
1814 				  int refs_to_mod,
1815 				  struct btrfs_delayed_extent_op *extent_op,
1816 				  int *last_ref)
1817 {
1818 	struct extent_buffer *leaf;
1819 	struct btrfs_extent_item *ei;
1820 	struct btrfs_extent_data_ref *dref = NULL;
1821 	struct btrfs_shared_data_ref *sref = NULL;
1822 	unsigned long ptr;
1823 	unsigned long end;
1824 	u32 item_size;
1825 	int size;
1826 	int type;
1827 	u64 refs;
1828 
1829 	leaf = path->nodes[0];
1830 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1831 	refs = btrfs_extent_refs(leaf, ei);
1832 	WARN_ON(refs_to_mod < 0 && refs + refs_to_mod <= 0);
1833 	refs += refs_to_mod;
1834 	btrfs_set_extent_refs(leaf, ei, refs);
1835 	if (extent_op)
1836 		__run_delayed_extent_op(extent_op, leaf, ei);
1837 
1838 	type = btrfs_extent_inline_ref_type(leaf, iref);
1839 
1840 	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1841 		dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1842 		refs = btrfs_extent_data_ref_count(leaf, dref);
1843 	} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1844 		sref = (struct btrfs_shared_data_ref *)(iref + 1);
1845 		refs = btrfs_shared_data_ref_count(leaf, sref);
1846 	} else {
1847 		refs = 1;
1848 		BUG_ON(refs_to_mod != -1);
1849 	}
1850 
1851 	BUG_ON(refs_to_mod < 0 && refs < -refs_to_mod);
1852 	refs += refs_to_mod;
1853 
1854 	if (refs > 0) {
1855 		if (type == BTRFS_EXTENT_DATA_REF_KEY)
1856 			btrfs_set_extent_data_ref_count(leaf, dref, refs);
1857 		else
1858 			btrfs_set_shared_data_ref_count(leaf, sref, refs);
1859 	} else {
1860 		*last_ref = 1;
1861 		size =  btrfs_extent_inline_ref_size(type);
1862 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1863 		ptr = (unsigned long)iref;
1864 		end = (unsigned long)ei + item_size;
1865 		if (ptr + size < end)
1866 			memmove_extent_buffer(leaf, ptr, ptr + size,
1867 					      end - ptr - size);
1868 		item_size -= size;
1869 		btrfs_truncate_item(root->fs_info, path, item_size, 1);
1870 	}
1871 	btrfs_mark_buffer_dirty(leaf);
1872 }
1873 
1874 static noinline_for_stack
1875 int insert_inline_extent_backref(struct btrfs_trans_handle *trans,
1876 				 struct btrfs_root *root,
1877 				 struct btrfs_path *path,
1878 				 u64 bytenr, u64 num_bytes, u64 parent,
1879 				 u64 root_objectid, u64 owner,
1880 				 u64 offset, int refs_to_add,
1881 				 struct btrfs_delayed_extent_op *extent_op)
1882 {
1883 	struct btrfs_extent_inline_ref *iref;
1884 	int ret;
1885 
1886 	ret = lookup_inline_extent_backref(trans, root, path, &iref,
1887 					   bytenr, num_bytes, parent,
1888 					   root_objectid, owner, offset, 1);
1889 	if (ret == 0) {
1890 		BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID);
1891 		update_inline_extent_backref(root, path, iref,
1892 					     refs_to_add, extent_op, NULL);
1893 	} else if (ret == -ENOENT) {
1894 		setup_inline_extent_backref(root, path, iref, parent,
1895 					    root_objectid, owner, offset,
1896 					    refs_to_add, extent_op);
1897 		ret = 0;
1898 	}
1899 	return ret;
1900 }
1901 
1902 static int insert_extent_backref(struct btrfs_trans_handle *trans,
1903 				 struct btrfs_root *root,
1904 				 struct btrfs_path *path,
1905 				 u64 bytenr, u64 parent, u64 root_objectid,
1906 				 u64 owner, u64 offset, int refs_to_add)
1907 {
1908 	int ret;
1909 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1910 		BUG_ON(refs_to_add != 1);
1911 		ret = insert_tree_block_ref(trans, root, path, bytenr,
1912 					    parent, root_objectid);
1913 	} else {
1914 		ret = insert_extent_data_ref(trans, root, path, bytenr,
1915 					     parent, root_objectid,
1916 					     owner, offset, refs_to_add);
1917 	}
1918 	return ret;
1919 }
1920 
1921 static int remove_extent_backref(struct btrfs_trans_handle *trans,
1922 				 struct btrfs_root *root,
1923 				 struct btrfs_path *path,
1924 				 struct btrfs_extent_inline_ref *iref,
1925 				 int refs_to_drop, int is_data, int *last_ref)
1926 {
1927 	int ret = 0;
1928 
1929 	BUG_ON(!is_data && refs_to_drop != 1);
1930 	if (iref) {
1931 		update_inline_extent_backref(root, path, iref,
1932 					     -refs_to_drop, NULL, last_ref);
1933 	} else if (is_data) {
1934 		ret = remove_extent_data_ref(trans, root, path, refs_to_drop,
1935 					     last_ref);
1936 	} else {
1937 		*last_ref = 1;
1938 		ret = btrfs_del_item(trans, root, path);
1939 	}
1940 	return ret;
1941 }
1942 
1943 #define in_range(b, first, len)        ((b) >= (first) && (b) < (first) + (len))
1944 static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
1945 			       u64 *discarded_bytes)
1946 {
1947 	int j, ret = 0;
1948 	u64 bytes_left, end;
1949 	u64 aligned_start = ALIGN(start, 1 << 9);
1950 
1951 	if (WARN_ON(start != aligned_start)) {
1952 		len -= aligned_start - start;
1953 		len = round_down(len, 1 << 9);
1954 		start = aligned_start;
1955 	}
1956 
1957 	*discarded_bytes = 0;
1958 
1959 	if (!len)
1960 		return 0;
1961 
1962 	end = start + len;
1963 	bytes_left = len;
1964 
1965 	/* Skip any superblocks on this device. */
1966 	for (j = 0; j < BTRFS_SUPER_MIRROR_MAX; j++) {
1967 		u64 sb_start = btrfs_sb_offset(j);
1968 		u64 sb_end = sb_start + BTRFS_SUPER_INFO_SIZE;
1969 		u64 size = sb_start - start;
1970 
1971 		if (!in_range(sb_start, start, bytes_left) &&
1972 		    !in_range(sb_end, start, bytes_left) &&
1973 		    !in_range(start, sb_start, BTRFS_SUPER_INFO_SIZE))
1974 			continue;
1975 
1976 		/*
1977 		 * Superblock spans beginning of range.  Adjust start and
1978 		 * try again.
1979 		 */
1980 		if (sb_start <= start) {
1981 			start += sb_end - start;
1982 			if (start > end) {
1983 				bytes_left = 0;
1984 				break;
1985 			}
1986 			bytes_left = end - start;
1987 			continue;
1988 		}
1989 
1990 		if (size) {
1991 			ret = blkdev_issue_discard(bdev, start >> 9, size >> 9,
1992 						   GFP_NOFS, 0);
1993 			if (!ret)
1994 				*discarded_bytes += size;
1995 			else if (ret != -EOPNOTSUPP)
1996 				return ret;
1997 		}
1998 
1999 		start = sb_end;
2000 		if (start > end) {
2001 			bytes_left = 0;
2002 			break;
2003 		}
2004 		bytes_left = end - start;
2005 	}
2006 
2007 	if (bytes_left) {
2008 		ret = blkdev_issue_discard(bdev, start >> 9, bytes_left >> 9,
2009 					   GFP_NOFS, 0);
2010 		if (!ret)
2011 			*discarded_bytes += bytes_left;
2012 	}
2013 	return ret;
2014 }
2015 
2016 int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
2017 			 u64 num_bytes, u64 *actual_bytes)
2018 {
2019 	int ret;
2020 	u64 discarded_bytes = 0;
2021 	struct btrfs_bio *bbio = NULL;
2022 
2023 
2024 	/*
2025 	 * Avoid races with device replace and make sure our bbio has devices
2026 	 * associated to its stripes that don't go away while we are discarding.
2027 	 */
2028 	btrfs_bio_counter_inc_blocked(fs_info);
2029 	/* Tell the block device(s) that the sectors can be discarded */
2030 	ret = btrfs_map_block(fs_info, BTRFS_MAP_DISCARD, bytenr, &num_bytes,
2031 			      &bbio, 0);
2032 	/* Error condition is -ENOMEM */
2033 	if (!ret) {
2034 		struct btrfs_bio_stripe *stripe = bbio->stripes;
2035 		int i;
2036 
2037 
2038 		for (i = 0; i < bbio->num_stripes; i++, stripe++) {
2039 			u64 bytes;
2040 			if (!stripe->dev->can_discard)
2041 				continue;
2042 
2043 			ret = btrfs_issue_discard(stripe->dev->bdev,
2044 						  stripe->physical,
2045 						  stripe->length,
2046 						  &bytes);
2047 			if (!ret)
2048 				discarded_bytes += bytes;
2049 			else if (ret != -EOPNOTSUPP)
2050 				break; /* Logic errors or -ENOMEM, or -EIO but I don't know how that could happen JDM */
2051 
2052 			/*
2053 			 * Just in case we get back EOPNOTSUPP for some reason,
2054 			 * just ignore the return value so we don't screw up
2055 			 * people calling discard_extent.
2056 			 */
2057 			ret = 0;
2058 		}
2059 		btrfs_put_bbio(bbio);
2060 	}
2061 	btrfs_bio_counter_dec(fs_info);
2062 
2063 	if (actual_bytes)
2064 		*actual_bytes = discarded_bytes;
2065 
2066 
2067 	if (ret == -EOPNOTSUPP)
2068 		ret = 0;
2069 	return ret;
2070 }
2071 
2072 /* Can return -ENOMEM */
2073 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
2074 			 struct btrfs_fs_info *fs_info,
2075 			 u64 bytenr, u64 num_bytes, u64 parent,
2076 			 u64 root_objectid, u64 owner, u64 offset)
2077 {
2078 	int ret;
2079 
2080 	BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID &&
2081 	       root_objectid == BTRFS_TREE_LOG_OBJECTID);
2082 
2083 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
2084 		ret = btrfs_add_delayed_tree_ref(fs_info, trans, bytenr,
2085 					num_bytes,
2086 					parent, root_objectid, (int)owner,
2087 					BTRFS_ADD_DELAYED_REF, NULL);
2088 	} else {
2089 		ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
2090 					num_bytes, parent, root_objectid,
2091 					owner, offset, 0,
2092 					BTRFS_ADD_DELAYED_REF, NULL);
2093 	}
2094 	return ret;
2095 }
2096 
2097 static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
2098 				  struct btrfs_fs_info *fs_info,
2099 				  struct btrfs_delayed_ref_node *node,
2100 				  u64 parent, u64 root_objectid,
2101 				  u64 owner, u64 offset, int refs_to_add,
2102 				  struct btrfs_delayed_extent_op *extent_op)
2103 {
2104 	struct btrfs_path *path;
2105 	struct extent_buffer *leaf;
2106 	struct btrfs_extent_item *item;
2107 	struct btrfs_key key;
2108 	u64 bytenr = node->bytenr;
2109 	u64 num_bytes = node->num_bytes;
2110 	u64 refs;
2111 	int ret;
2112 
2113 	path = btrfs_alloc_path();
2114 	if (!path)
2115 		return -ENOMEM;
2116 
2117 	path->reada = READA_FORWARD;
2118 	path->leave_spinning = 1;
2119 	/* this will setup the path even if it fails to insert the back ref */
2120 	ret = insert_inline_extent_backref(trans, fs_info->extent_root, path,
2121 					   bytenr, num_bytes, parent,
2122 					   root_objectid, owner, offset,
2123 					   refs_to_add, extent_op);
2124 	if ((ret < 0 && ret != -EAGAIN) || !ret)
2125 		goto out;
2126 
2127 	/*
2128 	 * Ok we had -EAGAIN which means we didn't have space to insert and
2129 	 * inline extent ref, so just update the reference count and add a
2130 	 * normal backref.
2131 	 */
2132 	leaf = path->nodes[0];
2133 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2134 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
2135 	refs = btrfs_extent_refs(leaf, item);
2136 	btrfs_set_extent_refs(leaf, item, refs + refs_to_add);
2137 	if (extent_op)
2138 		__run_delayed_extent_op(extent_op, leaf, item);
2139 
2140 	btrfs_mark_buffer_dirty(leaf);
2141 	btrfs_release_path(path);
2142 
2143 	path->reada = READA_FORWARD;
2144 	path->leave_spinning = 1;
2145 	/* now insert the actual backref */
2146 	ret = insert_extent_backref(trans, fs_info->extent_root,
2147 				    path, bytenr, parent, root_objectid,
2148 				    owner, offset, refs_to_add);
2149 	if (ret)
2150 		btrfs_abort_transaction(trans, ret);
2151 out:
2152 	btrfs_free_path(path);
2153 	return ret;
2154 }
2155 
2156 static int run_delayed_data_ref(struct btrfs_trans_handle *trans,
2157 				struct btrfs_fs_info *fs_info,
2158 				struct btrfs_delayed_ref_node *node,
2159 				struct btrfs_delayed_extent_op *extent_op,
2160 				int insert_reserved)
2161 {
2162 	int ret = 0;
2163 	struct btrfs_delayed_data_ref *ref;
2164 	struct btrfs_key ins;
2165 	u64 parent = 0;
2166 	u64 ref_root = 0;
2167 	u64 flags = 0;
2168 
2169 	ins.objectid = node->bytenr;
2170 	ins.offset = node->num_bytes;
2171 	ins.type = BTRFS_EXTENT_ITEM_KEY;
2172 
2173 	ref = btrfs_delayed_node_to_data_ref(node);
2174 	trace_run_delayed_data_ref(fs_info, node, ref, node->action);
2175 
2176 	if (node->type == BTRFS_SHARED_DATA_REF_KEY)
2177 		parent = ref->parent;
2178 	ref_root = ref->root;
2179 
2180 	if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
2181 		if (extent_op)
2182 			flags |= extent_op->flags_to_set;
2183 		ret = alloc_reserved_file_extent(trans, fs_info,
2184 						 parent, ref_root, flags,
2185 						 ref->objectid, ref->offset,
2186 						 &ins, node->ref_mod);
2187 	} else if (node->action == BTRFS_ADD_DELAYED_REF) {
2188 		ret = __btrfs_inc_extent_ref(trans, fs_info, node, parent,
2189 					     ref_root, ref->objectid,
2190 					     ref->offset, node->ref_mod,
2191 					     extent_op);
2192 	} else if (node->action == BTRFS_DROP_DELAYED_REF) {
2193 		ret = __btrfs_free_extent(trans, fs_info, node, parent,
2194 					  ref_root, ref->objectid,
2195 					  ref->offset, node->ref_mod,
2196 					  extent_op);
2197 	} else {
2198 		BUG();
2199 	}
2200 	return ret;
2201 }
2202 
2203 static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
2204 				    struct extent_buffer *leaf,
2205 				    struct btrfs_extent_item *ei)
2206 {
2207 	u64 flags = btrfs_extent_flags(leaf, ei);
2208 	if (extent_op->update_flags) {
2209 		flags |= extent_op->flags_to_set;
2210 		btrfs_set_extent_flags(leaf, ei, flags);
2211 	}
2212 
2213 	if (extent_op->update_key) {
2214 		struct btrfs_tree_block_info *bi;
2215 		BUG_ON(!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK));
2216 		bi = (struct btrfs_tree_block_info *)(ei + 1);
2217 		btrfs_set_tree_block_key(leaf, bi, &extent_op->key);
2218 	}
2219 }
2220 
2221 static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
2222 				 struct btrfs_fs_info *fs_info,
2223 				 struct btrfs_delayed_ref_node *node,
2224 				 struct btrfs_delayed_extent_op *extent_op)
2225 {
2226 	struct btrfs_key key;
2227 	struct btrfs_path *path;
2228 	struct btrfs_extent_item *ei;
2229 	struct extent_buffer *leaf;
2230 	u32 item_size;
2231 	int ret;
2232 	int err = 0;
2233 	int metadata = !extent_op->is_data;
2234 
2235 	if (trans->aborted)
2236 		return 0;
2237 
2238 	if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2239 		metadata = 0;
2240 
2241 	path = btrfs_alloc_path();
2242 	if (!path)
2243 		return -ENOMEM;
2244 
2245 	key.objectid = node->bytenr;
2246 
2247 	if (metadata) {
2248 		key.type = BTRFS_METADATA_ITEM_KEY;
2249 		key.offset = extent_op->level;
2250 	} else {
2251 		key.type = BTRFS_EXTENT_ITEM_KEY;
2252 		key.offset = node->num_bytes;
2253 	}
2254 
2255 again:
2256 	path->reada = READA_FORWARD;
2257 	path->leave_spinning = 1;
2258 	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 1);
2259 	if (ret < 0) {
2260 		err = ret;
2261 		goto out;
2262 	}
2263 	if (ret > 0) {
2264 		if (metadata) {
2265 			if (path->slots[0] > 0) {
2266 				path->slots[0]--;
2267 				btrfs_item_key_to_cpu(path->nodes[0], &key,
2268 						      path->slots[0]);
2269 				if (key.objectid == node->bytenr &&
2270 				    key.type == BTRFS_EXTENT_ITEM_KEY &&
2271 				    key.offset == node->num_bytes)
2272 					ret = 0;
2273 			}
2274 			if (ret > 0) {
2275 				btrfs_release_path(path);
2276 				metadata = 0;
2277 
2278 				key.objectid = node->bytenr;
2279 				key.offset = node->num_bytes;
2280 				key.type = BTRFS_EXTENT_ITEM_KEY;
2281 				goto again;
2282 			}
2283 		} else {
2284 			err = -EIO;
2285 			goto out;
2286 		}
2287 	}
2288 
2289 	leaf = path->nodes[0];
2290 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2291 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
2292 	if (item_size < sizeof(*ei)) {
2293 		ret = convert_extent_item_v0(trans, fs_info->extent_root,
2294 					     path, (u64)-1, 0);
2295 		if (ret < 0) {
2296 			err = ret;
2297 			goto out;
2298 		}
2299 		leaf = path->nodes[0];
2300 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2301 	}
2302 #endif
2303 	BUG_ON(item_size < sizeof(*ei));
2304 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
2305 	__run_delayed_extent_op(extent_op, leaf, ei);
2306 
2307 	btrfs_mark_buffer_dirty(leaf);
2308 out:
2309 	btrfs_free_path(path);
2310 	return err;
2311 }
2312 
2313 static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
2314 				struct btrfs_fs_info *fs_info,
2315 				struct btrfs_delayed_ref_node *node,
2316 				struct btrfs_delayed_extent_op *extent_op,
2317 				int insert_reserved)
2318 {
2319 	int ret = 0;
2320 	struct btrfs_delayed_tree_ref *ref;
2321 	struct btrfs_key ins;
2322 	u64 parent = 0;
2323 	u64 ref_root = 0;
2324 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
2325 
2326 	ref = btrfs_delayed_node_to_tree_ref(node);
2327 	trace_run_delayed_tree_ref(fs_info, node, ref, node->action);
2328 
2329 	if (node->type == BTRFS_SHARED_BLOCK_REF_KEY)
2330 		parent = ref->parent;
2331 	ref_root = ref->root;
2332 
2333 	ins.objectid = node->bytenr;
2334 	if (skinny_metadata) {
2335 		ins.offset = ref->level;
2336 		ins.type = BTRFS_METADATA_ITEM_KEY;
2337 	} else {
2338 		ins.offset = node->num_bytes;
2339 		ins.type = BTRFS_EXTENT_ITEM_KEY;
2340 	}
2341 
2342 	if (node->ref_mod != 1) {
2343 		btrfs_err(fs_info,
2344 	"btree block(%llu) has %d references rather than 1: action %d ref_root %llu parent %llu",
2345 			  node->bytenr, node->ref_mod, node->action, ref_root,
2346 			  parent);
2347 		return -EIO;
2348 	}
2349 	if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
2350 		BUG_ON(!extent_op || !extent_op->update_flags);
2351 		ret = alloc_reserved_tree_block(trans, fs_info,
2352 						parent, ref_root,
2353 						extent_op->flags_to_set,
2354 						&extent_op->key,
2355 						ref->level, &ins);
2356 	} else if (node->action == BTRFS_ADD_DELAYED_REF) {
2357 		ret = __btrfs_inc_extent_ref(trans, fs_info, node,
2358 					     parent, ref_root,
2359 					     ref->level, 0, 1,
2360 					     extent_op);
2361 	} else if (node->action == BTRFS_DROP_DELAYED_REF) {
2362 		ret = __btrfs_free_extent(trans, fs_info, node,
2363 					  parent, ref_root,
2364 					  ref->level, 0, 1, extent_op);
2365 	} else {
2366 		BUG();
2367 	}
2368 	return ret;
2369 }
2370 
2371 /* helper function to actually process a single delayed ref entry */
2372 static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
2373 			       struct btrfs_fs_info *fs_info,
2374 			       struct btrfs_delayed_ref_node *node,
2375 			       struct btrfs_delayed_extent_op *extent_op,
2376 			       int insert_reserved)
2377 {
2378 	int ret = 0;
2379 
2380 	if (trans->aborted) {
2381 		if (insert_reserved)
2382 			btrfs_pin_extent(fs_info, node->bytenr,
2383 					 node->num_bytes, 1);
2384 		return 0;
2385 	}
2386 
2387 	if (btrfs_delayed_ref_is_head(node)) {
2388 		struct btrfs_delayed_ref_head *head;
2389 		/*
2390 		 * we've hit the end of the chain and we were supposed
2391 		 * to insert this extent into the tree.  But, it got
2392 		 * deleted before we ever needed to insert it, so all
2393 		 * we have to do is clean up the accounting
2394 		 */
2395 		BUG_ON(extent_op);
2396 		head = btrfs_delayed_node_to_head(node);
2397 		trace_run_delayed_ref_head(fs_info, node, head, node->action);
2398 
2399 		if (insert_reserved) {
2400 			btrfs_pin_extent(fs_info, node->bytenr,
2401 					 node->num_bytes, 1);
2402 			if (head->is_data) {
2403 				ret = btrfs_del_csums(trans, fs_info,
2404 						      node->bytenr,
2405 						      node->num_bytes);
2406 			}
2407 		}
2408 
2409 		/* Also free its reserved qgroup space */
2410 		btrfs_qgroup_free_delayed_ref(fs_info, head->qgroup_ref_root,
2411 					      head->qgroup_reserved);
2412 		return ret;
2413 	}
2414 
2415 	if (node->type == BTRFS_TREE_BLOCK_REF_KEY ||
2416 	    node->type == BTRFS_SHARED_BLOCK_REF_KEY)
2417 		ret = run_delayed_tree_ref(trans, fs_info, node, extent_op,
2418 					   insert_reserved);
2419 	else if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
2420 		 node->type == BTRFS_SHARED_DATA_REF_KEY)
2421 		ret = run_delayed_data_ref(trans, fs_info, node, extent_op,
2422 					   insert_reserved);
2423 	else
2424 		BUG();
2425 	return ret;
2426 }
2427 
2428 static inline struct btrfs_delayed_ref_node *
2429 select_delayed_ref(struct btrfs_delayed_ref_head *head)
2430 {
2431 	struct btrfs_delayed_ref_node *ref;
2432 
2433 	if (list_empty(&head->ref_list))
2434 		return NULL;
2435 
2436 	/*
2437 	 * Select a delayed ref of type BTRFS_ADD_DELAYED_REF first.
2438 	 * This is to prevent a ref count from going down to zero, which deletes
2439 	 * the extent item from the extent tree, when there still are references
2440 	 * to add, which would fail because they would not find the extent item.
2441 	 */
2442 	if (!list_empty(&head->ref_add_list))
2443 		return list_first_entry(&head->ref_add_list,
2444 				struct btrfs_delayed_ref_node, add_list);
2445 
2446 	ref = list_first_entry(&head->ref_list, struct btrfs_delayed_ref_node,
2447 			       list);
2448 	ASSERT(list_empty(&ref->add_list));
2449 	return ref;
2450 }
2451 
2452 /*
2453  * Returns 0 on success or if called with an already aborted transaction.
2454  * Returns -ENOMEM or -EIO on failure and will abort the transaction.
2455  */
2456 static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
2457 					     struct btrfs_fs_info *fs_info,
2458 					     unsigned long nr)
2459 {
2460 	struct btrfs_delayed_ref_root *delayed_refs;
2461 	struct btrfs_delayed_ref_node *ref;
2462 	struct btrfs_delayed_ref_head *locked_ref = NULL;
2463 	struct btrfs_delayed_extent_op *extent_op;
2464 	ktime_t start = ktime_get();
2465 	int ret;
2466 	unsigned long count = 0;
2467 	unsigned long actual_count = 0;
2468 	int must_insert_reserved = 0;
2469 
2470 	delayed_refs = &trans->transaction->delayed_refs;
2471 	while (1) {
2472 		if (!locked_ref) {
2473 			if (count >= nr)
2474 				break;
2475 
2476 			spin_lock(&delayed_refs->lock);
2477 			locked_ref = btrfs_select_ref_head(trans);
2478 			if (!locked_ref) {
2479 				spin_unlock(&delayed_refs->lock);
2480 				break;
2481 			}
2482 
2483 			/* grab the lock that says we are going to process
2484 			 * all the refs for this head */
2485 			ret = btrfs_delayed_ref_lock(trans, locked_ref);
2486 			spin_unlock(&delayed_refs->lock);
2487 			/*
2488 			 * we may have dropped the spin lock to get the head
2489 			 * mutex lock, and that might have given someone else
2490 			 * time to free the head.  If that's true, it has been
2491 			 * removed from our list and we can move on.
2492 			 */
2493 			if (ret == -EAGAIN) {
2494 				locked_ref = NULL;
2495 				count++;
2496 				continue;
2497 			}
2498 		}
2499 
2500 		/*
2501 		 * We need to try and merge add/drops of the same ref since we
2502 		 * can run into issues with relocate dropping the implicit ref
2503 		 * and then it being added back again before the drop can
2504 		 * finish.  If we merged anything we need to re-loop so we can
2505 		 * get a good ref.
2506 		 * Or we can get node references of the same type that weren't
2507 		 * merged when created due to bumps in the tree mod seq, and
2508 		 * we need to merge them to prevent adding an inline extent
2509 		 * backref before dropping it (triggering a BUG_ON at
2510 		 * insert_inline_extent_backref()).
2511 		 */
2512 		spin_lock(&locked_ref->lock);
2513 		btrfs_merge_delayed_refs(trans, fs_info, delayed_refs,
2514 					 locked_ref);
2515 
2516 		/*
2517 		 * locked_ref is the head node, so we have to go one
2518 		 * node back for any delayed ref updates
2519 		 */
2520 		ref = select_delayed_ref(locked_ref);
2521 
2522 		if (ref && ref->seq &&
2523 		    btrfs_check_delayed_seq(fs_info, delayed_refs, ref->seq)) {
2524 			spin_unlock(&locked_ref->lock);
2525 			btrfs_delayed_ref_unlock(locked_ref);
2526 			spin_lock(&delayed_refs->lock);
2527 			locked_ref->processing = 0;
2528 			delayed_refs->num_heads_ready++;
2529 			spin_unlock(&delayed_refs->lock);
2530 			locked_ref = NULL;
2531 			cond_resched();
2532 			count++;
2533 			continue;
2534 		}
2535 
2536 		/*
2537 		 * record the must insert reserved flag before we
2538 		 * drop the spin lock.
2539 		 */
2540 		must_insert_reserved = locked_ref->must_insert_reserved;
2541 		locked_ref->must_insert_reserved = 0;
2542 
2543 		extent_op = locked_ref->extent_op;
2544 		locked_ref->extent_op = NULL;
2545 
2546 		if (!ref) {
2547 
2548 
2549 			/* All delayed refs have been processed, Go ahead
2550 			 * and send the head node to run_one_delayed_ref,
2551 			 * so that any accounting fixes can happen
2552 			 */
2553 			ref = &locked_ref->node;
2554 
2555 			if (extent_op && must_insert_reserved) {
2556 				btrfs_free_delayed_extent_op(extent_op);
2557 				extent_op = NULL;
2558 			}
2559 
2560 			if (extent_op) {
2561 				spin_unlock(&locked_ref->lock);
2562 				ret = run_delayed_extent_op(trans, fs_info,
2563 							    ref, extent_op);
2564 				btrfs_free_delayed_extent_op(extent_op);
2565 
2566 				if (ret) {
2567 					/*
2568 					 * Need to reset must_insert_reserved if
2569 					 * there was an error so the abort stuff
2570 					 * can cleanup the reserved space
2571 					 * properly.
2572 					 */
2573 					if (must_insert_reserved)
2574 						locked_ref->must_insert_reserved = 1;
2575 					locked_ref->processing = 0;
2576 					btrfs_debug(fs_info,
2577 						    "run_delayed_extent_op returned %d",
2578 						    ret);
2579 					btrfs_delayed_ref_unlock(locked_ref);
2580 					return ret;
2581 				}
2582 				continue;
2583 			}
2584 
2585 			/*
2586 			 * Need to drop our head ref lock and re-acquire the
2587 			 * delayed ref lock and then re-check to make sure
2588 			 * nobody got added.
2589 			 */
2590 			spin_unlock(&locked_ref->lock);
2591 			spin_lock(&delayed_refs->lock);
2592 			spin_lock(&locked_ref->lock);
2593 			if (!list_empty(&locked_ref->ref_list) ||
2594 			    locked_ref->extent_op) {
2595 				spin_unlock(&locked_ref->lock);
2596 				spin_unlock(&delayed_refs->lock);
2597 				continue;
2598 			}
2599 			ref->in_tree = 0;
2600 			delayed_refs->num_heads--;
2601 			rb_erase(&locked_ref->href_node,
2602 				 &delayed_refs->href_root);
2603 			spin_unlock(&delayed_refs->lock);
2604 		} else {
2605 			actual_count++;
2606 			ref->in_tree = 0;
2607 			list_del(&ref->list);
2608 			if (!list_empty(&ref->add_list))
2609 				list_del(&ref->add_list);
2610 		}
2611 		atomic_dec(&delayed_refs->num_entries);
2612 
2613 		if (!btrfs_delayed_ref_is_head(ref)) {
2614 			/*
2615 			 * when we play the delayed ref, also correct the
2616 			 * ref_mod on head
2617 			 */
2618 			switch (ref->action) {
2619 			case BTRFS_ADD_DELAYED_REF:
2620 			case BTRFS_ADD_DELAYED_EXTENT:
2621 				locked_ref->node.ref_mod -= ref->ref_mod;
2622 				break;
2623 			case BTRFS_DROP_DELAYED_REF:
2624 				locked_ref->node.ref_mod += ref->ref_mod;
2625 				break;
2626 			default:
2627 				WARN_ON(1);
2628 			}
2629 		}
2630 		spin_unlock(&locked_ref->lock);
2631 
2632 		ret = run_one_delayed_ref(trans, fs_info, ref, extent_op,
2633 					  must_insert_reserved);
2634 
2635 		btrfs_free_delayed_extent_op(extent_op);
2636 		if (ret) {
2637 			spin_lock(&delayed_refs->lock);
2638 			locked_ref->processing = 0;
2639 			delayed_refs->num_heads_ready++;
2640 			spin_unlock(&delayed_refs->lock);
2641 			btrfs_delayed_ref_unlock(locked_ref);
2642 			btrfs_put_delayed_ref(ref);
2643 			btrfs_debug(fs_info, "run_one_delayed_ref returned %d",
2644 				    ret);
2645 			return ret;
2646 		}
2647 
2648 		/*
2649 		 * If this node is a head, that means all the refs in this head
2650 		 * have been dealt with, and we will pick the next head to deal
2651 		 * with, so we must unlock the head and drop it from the cluster
2652 		 * list before we release it.
2653 		 */
2654 		if (btrfs_delayed_ref_is_head(ref)) {
2655 			if (locked_ref->is_data &&
2656 			    locked_ref->total_ref_mod < 0) {
2657 				spin_lock(&delayed_refs->lock);
2658 				delayed_refs->pending_csums -= ref->num_bytes;
2659 				spin_unlock(&delayed_refs->lock);
2660 			}
2661 			btrfs_delayed_ref_unlock(locked_ref);
2662 			locked_ref = NULL;
2663 		}
2664 		btrfs_put_delayed_ref(ref);
2665 		count++;
2666 		cond_resched();
2667 	}
2668 
2669 	/*
2670 	 * We don't want to include ref heads since we can have empty ref heads
2671 	 * and those will drastically skew our runtime down since we just do
2672 	 * accounting, no actual extent tree updates.
2673 	 */
2674 	if (actual_count > 0) {
2675 		u64 runtime = ktime_to_ns(ktime_sub(ktime_get(), start));
2676 		u64 avg;
2677 
2678 		/*
2679 		 * We weigh the current average higher than our current runtime
2680 		 * to avoid large swings in the average.
2681 		 */
2682 		spin_lock(&delayed_refs->lock);
2683 		avg = fs_info->avg_delayed_ref_runtime * 3 + runtime;
2684 		fs_info->avg_delayed_ref_runtime = avg >> 2;	/* div by 4 */
2685 		spin_unlock(&delayed_refs->lock);
2686 	}
2687 	return 0;
2688 }
2689 
2690 #ifdef SCRAMBLE_DELAYED_REFS
2691 /*
2692  * Normally delayed refs get processed in ascending bytenr order. This
2693  * correlates in most cases to the order added. To expose dependencies on this
2694  * order, we start to process the tree in the middle instead of the beginning
2695  */
2696 static u64 find_middle(struct rb_root *root)
2697 {
2698 	struct rb_node *n = root->rb_node;
2699 	struct btrfs_delayed_ref_node *entry;
2700 	int alt = 1;
2701 	u64 middle;
2702 	u64 first = 0, last = 0;
2703 
2704 	n = rb_first(root);
2705 	if (n) {
2706 		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2707 		first = entry->bytenr;
2708 	}
2709 	n = rb_last(root);
2710 	if (n) {
2711 		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2712 		last = entry->bytenr;
2713 	}
2714 	n = root->rb_node;
2715 
2716 	while (n) {
2717 		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2718 		WARN_ON(!entry->in_tree);
2719 
2720 		middle = entry->bytenr;
2721 
2722 		if (alt)
2723 			n = n->rb_left;
2724 		else
2725 			n = n->rb_right;
2726 
2727 		alt = 1 - alt;
2728 	}
2729 	return middle;
2730 }
2731 #endif
2732 
2733 static inline u64 heads_to_leaves(struct btrfs_fs_info *fs_info, u64 heads)
2734 {
2735 	u64 num_bytes;
2736 
2737 	num_bytes = heads * (sizeof(struct btrfs_extent_item) +
2738 			     sizeof(struct btrfs_extent_inline_ref));
2739 	if (!btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2740 		num_bytes += heads * sizeof(struct btrfs_tree_block_info);
2741 
2742 	/*
2743 	 * We don't ever fill up leaves all the way so multiply by 2 just to be
2744 	 * closer to what we're really going to want to use.
2745 	 */
2746 	return div_u64(num_bytes, BTRFS_LEAF_DATA_SIZE(fs_info));
2747 }
2748 
2749 /*
2750  * Takes the number of bytes to be csumm'ed and figures out how many leaves it
2751  * would require to store the csums for that many bytes.
2752  */
2753 u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes)
2754 {
2755 	u64 csum_size;
2756 	u64 num_csums_per_leaf;
2757 	u64 num_csums;
2758 
2759 	csum_size = BTRFS_MAX_ITEM_SIZE(fs_info);
2760 	num_csums_per_leaf = div64_u64(csum_size,
2761 			(u64)btrfs_super_csum_size(fs_info->super_copy));
2762 	num_csums = div64_u64(csum_bytes, fs_info->sectorsize);
2763 	num_csums += num_csums_per_leaf - 1;
2764 	num_csums = div64_u64(num_csums, num_csums_per_leaf);
2765 	return num_csums;
2766 }
2767 
2768 int btrfs_check_space_for_delayed_refs(struct btrfs_trans_handle *trans,
2769 				       struct btrfs_fs_info *fs_info)
2770 {
2771 	struct btrfs_block_rsv *global_rsv;
2772 	u64 num_heads = trans->transaction->delayed_refs.num_heads_ready;
2773 	u64 csum_bytes = trans->transaction->delayed_refs.pending_csums;
2774 	u64 num_dirty_bgs = trans->transaction->num_dirty_bgs;
2775 	u64 num_bytes, num_dirty_bgs_bytes;
2776 	int ret = 0;
2777 
2778 	num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
2779 	num_heads = heads_to_leaves(fs_info, num_heads);
2780 	if (num_heads > 1)
2781 		num_bytes += (num_heads - 1) * fs_info->nodesize;
2782 	num_bytes <<= 1;
2783 	num_bytes += btrfs_csum_bytes_to_leaves(fs_info, csum_bytes) *
2784 							fs_info->nodesize;
2785 	num_dirty_bgs_bytes = btrfs_calc_trans_metadata_size(fs_info,
2786 							     num_dirty_bgs);
2787 	global_rsv = &fs_info->global_block_rsv;
2788 
2789 	/*
2790 	 * If we can't allocate any more chunks lets make sure we have _lots_ of
2791 	 * wiggle room since running delayed refs can create more delayed refs.
2792 	 */
2793 	if (global_rsv->space_info->full) {
2794 		num_dirty_bgs_bytes <<= 1;
2795 		num_bytes <<= 1;
2796 	}
2797 
2798 	spin_lock(&global_rsv->lock);
2799 	if (global_rsv->reserved <= num_bytes + num_dirty_bgs_bytes)
2800 		ret = 1;
2801 	spin_unlock(&global_rsv->lock);
2802 	return ret;
2803 }
2804 
2805 int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans,
2806 				       struct btrfs_fs_info *fs_info)
2807 {
2808 	u64 num_entries =
2809 		atomic_read(&trans->transaction->delayed_refs.num_entries);
2810 	u64 avg_runtime;
2811 	u64 val;
2812 
2813 	smp_mb();
2814 	avg_runtime = fs_info->avg_delayed_ref_runtime;
2815 	val = num_entries * avg_runtime;
2816 	if (val >= NSEC_PER_SEC)
2817 		return 1;
2818 	if (val >= NSEC_PER_SEC / 2)
2819 		return 2;
2820 
2821 	return btrfs_check_space_for_delayed_refs(trans, fs_info);
2822 }
2823 
2824 struct async_delayed_refs {
2825 	struct btrfs_root *root;
2826 	u64 transid;
2827 	int count;
2828 	int error;
2829 	int sync;
2830 	struct completion wait;
2831 	struct btrfs_work work;
2832 };
2833 
2834 static inline struct async_delayed_refs *
2835 to_async_delayed_refs(struct btrfs_work *work)
2836 {
2837 	return container_of(work, struct async_delayed_refs, work);
2838 }
2839 
2840 static void delayed_ref_async_start(struct btrfs_work *work)
2841 {
2842 	struct async_delayed_refs *async = to_async_delayed_refs(work);
2843 	struct btrfs_trans_handle *trans;
2844 	struct btrfs_fs_info *fs_info = async->root->fs_info;
2845 	int ret;
2846 
2847 	/* if the commit is already started, we don't need to wait here */
2848 	if (btrfs_transaction_blocked(fs_info))
2849 		goto done;
2850 
2851 	trans = btrfs_join_transaction(async->root);
2852 	if (IS_ERR(trans)) {
2853 		async->error = PTR_ERR(trans);
2854 		goto done;
2855 	}
2856 
2857 	/*
2858 	 * trans->sync means that when we call end_transaction, we won't
2859 	 * wait on delayed refs
2860 	 */
2861 	trans->sync = true;
2862 
2863 	/* Don't bother flushing if we got into a different transaction */
2864 	if (trans->transid > async->transid)
2865 		goto end;
2866 
2867 	ret = btrfs_run_delayed_refs(trans, fs_info, async->count);
2868 	if (ret)
2869 		async->error = ret;
2870 end:
2871 	ret = btrfs_end_transaction(trans);
2872 	if (ret && !async->error)
2873 		async->error = ret;
2874 done:
2875 	if (async->sync)
2876 		complete(&async->wait);
2877 	else
2878 		kfree(async);
2879 }
2880 
2881 int btrfs_async_run_delayed_refs(struct btrfs_fs_info *fs_info,
2882 				 unsigned long count, u64 transid, int wait)
2883 {
2884 	struct async_delayed_refs *async;
2885 	int ret;
2886 
2887 	async = kmalloc(sizeof(*async), GFP_NOFS);
2888 	if (!async)
2889 		return -ENOMEM;
2890 
2891 	async->root = fs_info->tree_root;
2892 	async->count = count;
2893 	async->error = 0;
2894 	async->transid = transid;
2895 	if (wait)
2896 		async->sync = 1;
2897 	else
2898 		async->sync = 0;
2899 	init_completion(&async->wait);
2900 
2901 	btrfs_init_work(&async->work, btrfs_extent_refs_helper,
2902 			delayed_ref_async_start, NULL, NULL);
2903 
2904 	btrfs_queue_work(fs_info->extent_workers, &async->work);
2905 
2906 	if (wait) {
2907 		wait_for_completion(&async->wait);
2908 		ret = async->error;
2909 		kfree(async);
2910 		return ret;
2911 	}
2912 	return 0;
2913 }
2914 
2915 /*
2916  * this starts processing the delayed reference count updates and
2917  * extent insertions we have queued up so far.  count can be
2918  * 0, which means to process everything in the tree at the start
2919  * of the run (but not newly added entries), or it can be some target
2920  * number you'd like to process.
2921  *
2922  * Returns 0 on success or if called with an aborted transaction
2923  * Returns <0 on error and aborts the transaction
2924  */
2925 int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
2926 			   struct btrfs_fs_info *fs_info, unsigned long count)
2927 {
2928 	struct rb_node *node;
2929 	struct btrfs_delayed_ref_root *delayed_refs;
2930 	struct btrfs_delayed_ref_head *head;
2931 	int ret;
2932 	int run_all = count == (unsigned long)-1;
2933 	bool can_flush_pending_bgs = trans->can_flush_pending_bgs;
2934 
2935 	/* We'll clean this up in btrfs_cleanup_transaction */
2936 	if (trans->aborted)
2937 		return 0;
2938 
2939 	if (test_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags))
2940 		return 0;
2941 
2942 	delayed_refs = &trans->transaction->delayed_refs;
2943 	if (count == 0)
2944 		count = atomic_read(&delayed_refs->num_entries) * 2;
2945 
2946 again:
2947 #ifdef SCRAMBLE_DELAYED_REFS
2948 	delayed_refs->run_delayed_start = find_middle(&delayed_refs->root);
2949 #endif
2950 	trans->can_flush_pending_bgs = false;
2951 	ret = __btrfs_run_delayed_refs(trans, fs_info, count);
2952 	if (ret < 0) {
2953 		btrfs_abort_transaction(trans, ret);
2954 		return ret;
2955 	}
2956 
2957 	if (run_all) {
2958 		if (!list_empty(&trans->new_bgs))
2959 			btrfs_create_pending_block_groups(trans, fs_info);
2960 
2961 		spin_lock(&delayed_refs->lock);
2962 		node = rb_first(&delayed_refs->href_root);
2963 		if (!node) {
2964 			spin_unlock(&delayed_refs->lock);
2965 			goto out;
2966 		}
2967 
2968 		while (node) {
2969 			head = rb_entry(node, struct btrfs_delayed_ref_head,
2970 					href_node);
2971 			if (btrfs_delayed_ref_is_head(&head->node)) {
2972 				struct btrfs_delayed_ref_node *ref;
2973 
2974 				ref = &head->node;
2975 				atomic_inc(&ref->refs);
2976 
2977 				spin_unlock(&delayed_refs->lock);
2978 				/*
2979 				 * Mutex was contended, block until it's
2980 				 * released and try again
2981 				 */
2982 				mutex_lock(&head->mutex);
2983 				mutex_unlock(&head->mutex);
2984 
2985 				btrfs_put_delayed_ref(ref);
2986 				cond_resched();
2987 				goto again;
2988 			} else {
2989 				WARN_ON(1);
2990 			}
2991 			node = rb_next(node);
2992 		}
2993 		spin_unlock(&delayed_refs->lock);
2994 		cond_resched();
2995 		goto again;
2996 	}
2997 out:
2998 	assert_qgroups_uptodate(trans);
2999 	trans->can_flush_pending_bgs = can_flush_pending_bgs;
3000 	return 0;
3001 }
3002 
3003 int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
3004 				struct btrfs_fs_info *fs_info,
3005 				u64 bytenr, u64 num_bytes, u64 flags,
3006 				int level, int is_data)
3007 {
3008 	struct btrfs_delayed_extent_op *extent_op;
3009 	int ret;
3010 
3011 	extent_op = btrfs_alloc_delayed_extent_op();
3012 	if (!extent_op)
3013 		return -ENOMEM;
3014 
3015 	extent_op->flags_to_set = flags;
3016 	extent_op->update_flags = true;
3017 	extent_op->update_key = false;
3018 	extent_op->is_data = is_data ? true : false;
3019 	extent_op->level = level;
3020 
3021 	ret = btrfs_add_delayed_extent_op(fs_info, trans, bytenr,
3022 					  num_bytes, extent_op);
3023 	if (ret)
3024 		btrfs_free_delayed_extent_op(extent_op);
3025 	return ret;
3026 }
3027 
3028 static noinline int check_delayed_ref(struct btrfs_trans_handle *trans,
3029 				      struct btrfs_root *root,
3030 				      struct btrfs_path *path,
3031 				      u64 objectid, u64 offset, u64 bytenr)
3032 {
3033 	struct btrfs_delayed_ref_head *head;
3034 	struct btrfs_delayed_ref_node *ref;
3035 	struct btrfs_delayed_data_ref *data_ref;
3036 	struct btrfs_delayed_ref_root *delayed_refs;
3037 	int ret = 0;
3038 
3039 	delayed_refs = &trans->transaction->delayed_refs;
3040 	spin_lock(&delayed_refs->lock);
3041 	head = btrfs_find_delayed_ref_head(trans, bytenr);
3042 	if (!head) {
3043 		spin_unlock(&delayed_refs->lock);
3044 		return 0;
3045 	}
3046 
3047 	if (!mutex_trylock(&head->mutex)) {
3048 		atomic_inc(&head->node.refs);
3049 		spin_unlock(&delayed_refs->lock);
3050 
3051 		btrfs_release_path(path);
3052 
3053 		/*
3054 		 * Mutex was contended, block until it's released and let
3055 		 * caller try again
3056 		 */
3057 		mutex_lock(&head->mutex);
3058 		mutex_unlock(&head->mutex);
3059 		btrfs_put_delayed_ref(&head->node);
3060 		return -EAGAIN;
3061 	}
3062 	spin_unlock(&delayed_refs->lock);
3063 
3064 	spin_lock(&head->lock);
3065 	list_for_each_entry(ref, &head->ref_list, list) {
3066 		/* If it's a shared ref we know a cross reference exists */
3067 		if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) {
3068 			ret = 1;
3069 			break;
3070 		}
3071 
3072 		data_ref = btrfs_delayed_node_to_data_ref(ref);
3073 
3074 		/*
3075 		 * If our ref doesn't match the one we're currently looking at
3076 		 * then we have a cross reference.
3077 		 */
3078 		if (data_ref->root != root->root_key.objectid ||
3079 		    data_ref->objectid != objectid ||
3080 		    data_ref->offset != offset) {
3081 			ret = 1;
3082 			break;
3083 		}
3084 	}
3085 	spin_unlock(&head->lock);
3086 	mutex_unlock(&head->mutex);
3087 	return ret;
3088 }
3089 
3090 static noinline int check_committed_ref(struct btrfs_trans_handle *trans,
3091 					struct btrfs_root *root,
3092 					struct btrfs_path *path,
3093 					u64 objectid, u64 offset, u64 bytenr)
3094 {
3095 	struct btrfs_fs_info *fs_info = root->fs_info;
3096 	struct btrfs_root *extent_root = fs_info->extent_root;
3097 	struct extent_buffer *leaf;
3098 	struct btrfs_extent_data_ref *ref;
3099 	struct btrfs_extent_inline_ref *iref;
3100 	struct btrfs_extent_item *ei;
3101 	struct btrfs_key key;
3102 	u32 item_size;
3103 	int ret;
3104 
3105 	key.objectid = bytenr;
3106 	key.offset = (u64)-1;
3107 	key.type = BTRFS_EXTENT_ITEM_KEY;
3108 
3109 	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
3110 	if (ret < 0)
3111 		goto out;
3112 	BUG_ON(ret == 0); /* Corruption */
3113 
3114 	ret = -ENOENT;
3115 	if (path->slots[0] == 0)
3116 		goto out;
3117 
3118 	path->slots[0]--;
3119 	leaf = path->nodes[0];
3120 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3121 
3122 	if (key.objectid != bytenr || key.type != BTRFS_EXTENT_ITEM_KEY)
3123 		goto out;
3124 
3125 	ret = 1;
3126 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3127 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3128 	if (item_size < sizeof(*ei)) {
3129 		WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3130 		goto out;
3131 	}
3132 #endif
3133 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
3134 
3135 	if (item_size != sizeof(*ei) +
3136 	    btrfs_extent_inline_ref_size(BTRFS_EXTENT_DATA_REF_KEY))
3137 		goto out;
3138 
3139 	if (btrfs_extent_generation(leaf, ei) <=
3140 	    btrfs_root_last_snapshot(&root->root_item))
3141 		goto out;
3142 
3143 	iref = (struct btrfs_extent_inline_ref *)(ei + 1);
3144 	if (btrfs_extent_inline_ref_type(leaf, iref) !=
3145 	    BTRFS_EXTENT_DATA_REF_KEY)
3146 		goto out;
3147 
3148 	ref = (struct btrfs_extent_data_ref *)(&iref->offset);
3149 	if (btrfs_extent_refs(leaf, ei) !=
3150 	    btrfs_extent_data_ref_count(leaf, ref) ||
3151 	    btrfs_extent_data_ref_root(leaf, ref) !=
3152 	    root->root_key.objectid ||
3153 	    btrfs_extent_data_ref_objectid(leaf, ref) != objectid ||
3154 	    btrfs_extent_data_ref_offset(leaf, ref) != offset)
3155 		goto out;
3156 
3157 	ret = 0;
3158 out:
3159 	return ret;
3160 }
3161 
3162 int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
3163 			  struct btrfs_root *root,
3164 			  u64 objectid, u64 offset, u64 bytenr)
3165 {
3166 	struct btrfs_path *path;
3167 	int ret;
3168 	int ret2;
3169 
3170 	path = btrfs_alloc_path();
3171 	if (!path)
3172 		return -ENOENT;
3173 
3174 	do {
3175 		ret = check_committed_ref(trans, root, path, objectid,
3176 					  offset, bytenr);
3177 		if (ret && ret != -ENOENT)
3178 			goto out;
3179 
3180 		ret2 = check_delayed_ref(trans, root, path, objectid,
3181 					 offset, bytenr);
3182 	} while (ret2 == -EAGAIN);
3183 
3184 	if (ret2 && ret2 != -ENOENT) {
3185 		ret = ret2;
3186 		goto out;
3187 	}
3188 
3189 	if (ret != -ENOENT || ret2 != -ENOENT)
3190 		ret = 0;
3191 out:
3192 	btrfs_free_path(path);
3193 	if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
3194 		WARN_ON(ret > 0);
3195 	return ret;
3196 }
3197 
3198 static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
3199 			   struct btrfs_root *root,
3200 			   struct extent_buffer *buf,
3201 			   int full_backref, int inc)
3202 {
3203 	struct btrfs_fs_info *fs_info = root->fs_info;
3204 	u64 bytenr;
3205 	u64 num_bytes;
3206 	u64 parent;
3207 	u64 ref_root;
3208 	u32 nritems;
3209 	struct btrfs_key key;
3210 	struct btrfs_file_extent_item *fi;
3211 	int i;
3212 	int level;
3213 	int ret = 0;
3214 	int (*process_func)(struct btrfs_trans_handle *,
3215 			    struct btrfs_fs_info *,
3216 			    u64, u64, u64, u64, u64, u64);
3217 
3218 
3219 	if (btrfs_is_testing(fs_info))
3220 		return 0;
3221 
3222 	ref_root = btrfs_header_owner(buf);
3223 	nritems = btrfs_header_nritems(buf);
3224 	level = btrfs_header_level(buf);
3225 
3226 	if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state) && level == 0)
3227 		return 0;
3228 
3229 	if (inc)
3230 		process_func = btrfs_inc_extent_ref;
3231 	else
3232 		process_func = btrfs_free_extent;
3233 
3234 	if (full_backref)
3235 		parent = buf->start;
3236 	else
3237 		parent = 0;
3238 
3239 	for (i = 0; i < nritems; i++) {
3240 		if (level == 0) {
3241 			btrfs_item_key_to_cpu(buf, &key, i);
3242 			if (key.type != BTRFS_EXTENT_DATA_KEY)
3243 				continue;
3244 			fi = btrfs_item_ptr(buf, i,
3245 					    struct btrfs_file_extent_item);
3246 			if (btrfs_file_extent_type(buf, fi) ==
3247 			    BTRFS_FILE_EXTENT_INLINE)
3248 				continue;
3249 			bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
3250 			if (bytenr == 0)
3251 				continue;
3252 
3253 			num_bytes = btrfs_file_extent_disk_num_bytes(buf, fi);
3254 			key.offset -= btrfs_file_extent_offset(buf, fi);
3255 			ret = process_func(trans, fs_info, bytenr, num_bytes,
3256 					   parent, ref_root, key.objectid,
3257 					   key.offset);
3258 			if (ret)
3259 				goto fail;
3260 		} else {
3261 			bytenr = btrfs_node_blockptr(buf, i);
3262 			num_bytes = fs_info->nodesize;
3263 			ret = process_func(trans, fs_info, bytenr, num_bytes,
3264 					   parent, ref_root, level - 1, 0);
3265 			if (ret)
3266 				goto fail;
3267 		}
3268 	}
3269 	return 0;
3270 fail:
3271 	return ret;
3272 }
3273 
3274 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3275 		  struct extent_buffer *buf, int full_backref)
3276 {
3277 	return __btrfs_mod_ref(trans, root, buf, full_backref, 1);
3278 }
3279 
3280 int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3281 		  struct extent_buffer *buf, int full_backref)
3282 {
3283 	return __btrfs_mod_ref(trans, root, buf, full_backref, 0);
3284 }
3285 
3286 static int write_one_cache_group(struct btrfs_trans_handle *trans,
3287 				 struct btrfs_fs_info *fs_info,
3288 				 struct btrfs_path *path,
3289 				 struct btrfs_block_group_cache *cache)
3290 {
3291 	int ret;
3292 	struct btrfs_root *extent_root = fs_info->extent_root;
3293 	unsigned long bi;
3294 	struct extent_buffer *leaf;
3295 
3296 	ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
3297 	if (ret) {
3298 		if (ret > 0)
3299 			ret = -ENOENT;
3300 		goto fail;
3301 	}
3302 
3303 	leaf = path->nodes[0];
3304 	bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
3305 	write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
3306 	btrfs_mark_buffer_dirty(leaf);
3307 fail:
3308 	btrfs_release_path(path);
3309 	return ret;
3310 
3311 }
3312 
3313 static struct btrfs_block_group_cache *
3314 next_block_group(struct btrfs_fs_info *fs_info,
3315 		 struct btrfs_block_group_cache *cache)
3316 {
3317 	struct rb_node *node;
3318 
3319 	spin_lock(&fs_info->block_group_cache_lock);
3320 
3321 	/* If our block group was removed, we need a full search. */
3322 	if (RB_EMPTY_NODE(&cache->cache_node)) {
3323 		const u64 next_bytenr = cache->key.objectid + cache->key.offset;
3324 
3325 		spin_unlock(&fs_info->block_group_cache_lock);
3326 		btrfs_put_block_group(cache);
3327 		cache = btrfs_lookup_first_block_group(fs_info, next_bytenr); return cache;
3328 	}
3329 	node = rb_next(&cache->cache_node);
3330 	btrfs_put_block_group(cache);
3331 	if (node) {
3332 		cache = rb_entry(node, struct btrfs_block_group_cache,
3333 				 cache_node);
3334 		btrfs_get_block_group(cache);
3335 	} else
3336 		cache = NULL;
3337 	spin_unlock(&fs_info->block_group_cache_lock);
3338 	return cache;
3339 }
3340 
3341 static int cache_save_setup(struct btrfs_block_group_cache *block_group,
3342 			    struct btrfs_trans_handle *trans,
3343 			    struct btrfs_path *path)
3344 {
3345 	struct btrfs_fs_info *fs_info = block_group->fs_info;
3346 	struct btrfs_root *root = fs_info->tree_root;
3347 	struct inode *inode = NULL;
3348 	u64 alloc_hint = 0;
3349 	int dcs = BTRFS_DC_ERROR;
3350 	u64 num_pages = 0;
3351 	int retries = 0;
3352 	int ret = 0;
3353 
3354 	/*
3355 	 * If this block group is smaller than 100 megs don't bother caching the
3356 	 * block group.
3357 	 */
3358 	if (block_group->key.offset < (100 * SZ_1M)) {
3359 		spin_lock(&block_group->lock);
3360 		block_group->disk_cache_state = BTRFS_DC_WRITTEN;
3361 		spin_unlock(&block_group->lock);
3362 		return 0;
3363 	}
3364 
3365 	if (trans->aborted)
3366 		return 0;
3367 again:
3368 	inode = lookup_free_space_inode(root, block_group, path);
3369 	if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
3370 		ret = PTR_ERR(inode);
3371 		btrfs_release_path(path);
3372 		goto out;
3373 	}
3374 
3375 	if (IS_ERR(inode)) {
3376 		BUG_ON(retries);
3377 		retries++;
3378 
3379 		if (block_group->ro)
3380 			goto out_free;
3381 
3382 		ret = create_free_space_inode(root, trans, block_group, path);
3383 		if (ret)
3384 			goto out_free;
3385 		goto again;
3386 	}
3387 
3388 	/* We've already setup this transaction, go ahead and exit */
3389 	if (block_group->cache_generation == trans->transid &&
3390 	    i_size_read(inode)) {
3391 		dcs = BTRFS_DC_SETUP;
3392 		goto out_put;
3393 	}
3394 
3395 	/*
3396 	 * We want to set the generation to 0, that way if anything goes wrong
3397 	 * from here on out we know not to trust this cache when we load up next
3398 	 * time.
3399 	 */
3400 	BTRFS_I(inode)->generation = 0;
3401 	ret = btrfs_update_inode(trans, root, inode);
3402 	if (ret) {
3403 		/*
3404 		 * So theoretically we could recover from this, simply set the
3405 		 * super cache generation to 0 so we know to invalidate the
3406 		 * cache, but then we'd have to keep track of the block groups
3407 		 * that fail this way so we know we _have_ to reset this cache
3408 		 * before the next commit or risk reading stale cache.  So to
3409 		 * limit our exposure to horrible edge cases lets just abort the
3410 		 * transaction, this only happens in really bad situations
3411 		 * anyway.
3412 		 */
3413 		btrfs_abort_transaction(trans, ret);
3414 		goto out_put;
3415 	}
3416 	WARN_ON(ret);
3417 
3418 	if (i_size_read(inode) > 0) {
3419 		ret = btrfs_check_trunc_cache_free_space(fs_info,
3420 					&fs_info->global_block_rsv);
3421 		if (ret)
3422 			goto out_put;
3423 
3424 		ret = btrfs_truncate_free_space_cache(root, trans, NULL, inode);
3425 		if (ret)
3426 			goto out_put;
3427 	}
3428 
3429 	spin_lock(&block_group->lock);
3430 	if (block_group->cached != BTRFS_CACHE_FINISHED ||
3431 	    !btrfs_test_opt(fs_info, SPACE_CACHE)) {
3432 		/*
3433 		 * don't bother trying to write stuff out _if_
3434 		 * a) we're not cached,
3435 		 * b) we're with nospace_cache mount option.
3436 		 */
3437 		dcs = BTRFS_DC_WRITTEN;
3438 		spin_unlock(&block_group->lock);
3439 		goto out_put;
3440 	}
3441 	spin_unlock(&block_group->lock);
3442 
3443 	/*
3444 	 * We hit an ENOSPC when setting up the cache in this transaction, just
3445 	 * skip doing the setup, we've already cleared the cache so we're safe.
3446 	 */
3447 	if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) {
3448 		ret = -ENOSPC;
3449 		goto out_put;
3450 	}
3451 
3452 	/*
3453 	 * Try to preallocate enough space based on how big the block group is.
3454 	 * Keep in mind this has to include any pinned space which could end up
3455 	 * taking up quite a bit since it's not folded into the other space
3456 	 * cache.
3457 	 */
3458 	num_pages = div_u64(block_group->key.offset, SZ_256M);
3459 	if (!num_pages)
3460 		num_pages = 1;
3461 
3462 	num_pages *= 16;
3463 	num_pages *= PAGE_SIZE;
3464 
3465 	ret = btrfs_check_data_free_space(inode, 0, num_pages);
3466 	if (ret)
3467 		goto out_put;
3468 
3469 	ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
3470 					      num_pages, num_pages,
3471 					      &alloc_hint);
3472 	/*
3473 	 * Our cache requires contiguous chunks so that we don't modify a bunch
3474 	 * of metadata or split extents when writing the cache out, which means
3475 	 * we can enospc if we are heavily fragmented in addition to just normal
3476 	 * out of space conditions.  So if we hit this just skip setting up any
3477 	 * other block groups for this transaction, maybe we'll unpin enough
3478 	 * space the next time around.
3479 	 */
3480 	if (!ret)
3481 		dcs = BTRFS_DC_SETUP;
3482 	else if (ret == -ENOSPC)
3483 		set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
3484 
3485 out_put:
3486 	iput(inode);
3487 out_free:
3488 	btrfs_release_path(path);
3489 out:
3490 	spin_lock(&block_group->lock);
3491 	if (!ret && dcs == BTRFS_DC_SETUP)
3492 		block_group->cache_generation = trans->transid;
3493 	block_group->disk_cache_state = dcs;
3494 	spin_unlock(&block_group->lock);
3495 
3496 	return ret;
3497 }
3498 
3499 int btrfs_setup_space_cache(struct btrfs_trans_handle *trans,
3500 			    struct btrfs_fs_info *fs_info)
3501 {
3502 	struct btrfs_block_group_cache *cache, *tmp;
3503 	struct btrfs_transaction *cur_trans = trans->transaction;
3504 	struct btrfs_path *path;
3505 
3506 	if (list_empty(&cur_trans->dirty_bgs) ||
3507 	    !btrfs_test_opt(fs_info, SPACE_CACHE))
3508 		return 0;
3509 
3510 	path = btrfs_alloc_path();
3511 	if (!path)
3512 		return -ENOMEM;
3513 
3514 	/* Could add new block groups, use _safe just in case */
3515 	list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs,
3516 				 dirty_list) {
3517 		if (cache->disk_cache_state == BTRFS_DC_CLEAR)
3518 			cache_save_setup(cache, trans, path);
3519 	}
3520 
3521 	btrfs_free_path(path);
3522 	return 0;
3523 }
3524 
3525 /*
3526  * transaction commit does final block group cache writeback during a
3527  * critical section where nothing is allowed to change the FS.  This is
3528  * required in order for the cache to actually match the block group,
3529  * but can introduce a lot of latency into the commit.
3530  *
3531  * So, btrfs_start_dirty_block_groups is here to kick off block group
3532  * cache IO.  There's a chance we'll have to redo some of it if the
3533  * block group changes again during the commit, but it greatly reduces
3534  * the commit latency by getting rid of the easy block groups while
3535  * we're still allowing others to join the commit.
3536  */
3537 int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans,
3538 				   struct btrfs_fs_info *fs_info)
3539 {
3540 	struct btrfs_block_group_cache *cache;
3541 	struct btrfs_transaction *cur_trans = trans->transaction;
3542 	int ret = 0;
3543 	int should_put;
3544 	struct btrfs_path *path = NULL;
3545 	LIST_HEAD(dirty);
3546 	struct list_head *io = &cur_trans->io_bgs;
3547 	int num_started = 0;
3548 	int loops = 0;
3549 
3550 	spin_lock(&cur_trans->dirty_bgs_lock);
3551 	if (list_empty(&cur_trans->dirty_bgs)) {
3552 		spin_unlock(&cur_trans->dirty_bgs_lock);
3553 		return 0;
3554 	}
3555 	list_splice_init(&cur_trans->dirty_bgs, &dirty);
3556 	spin_unlock(&cur_trans->dirty_bgs_lock);
3557 
3558 again:
3559 	/*
3560 	 * make sure all the block groups on our dirty list actually
3561 	 * exist
3562 	 */
3563 	btrfs_create_pending_block_groups(trans, fs_info);
3564 
3565 	if (!path) {
3566 		path = btrfs_alloc_path();
3567 		if (!path)
3568 			return -ENOMEM;
3569 	}
3570 
3571 	/*
3572 	 * cache_write_mutex is here only to save us from balance or automatic
3573 	 * removal of empty block groups deleting this block group while we are
3574 	 * writing out the cache
3575 	 */
3576 	mutex_lock(&trans->transaction->cache_write_mutex);
3577 	while (!list_empty(&dirty)) {
3578 		cache = list_first_entry(&dirty,
3579 					 struct btrfs_block_group_cache,
3580 					 dirty_list);
3581 		/*
3582 		 * this can happen if something re-dirties a block
3583 		 * group that is already under IO.  Just wait for it to
3584 		 * finish and then do it all again
3585 		 */
3586 		if (!list_empty(&cache->io_list)) {
3587 			list_del_init(&cache->io_list);
3588 			btrfs_wait_cache_io(trans, cache, path);
3589 			btrfs_put_block_group(cache);
3590 		}
3591 
3592 
3593 		/*
3594 		 * btrfs_wait_cache_io uses the cache->dirty_list to decide
3595 		 * if it should update the cache_state.  Don't delete
3596 		 * until after we wait.
3597 		 *
3598 		 * Since we're not running in the commit critical section
3599 		 * we need the dirty_bgs_lock to protect from update_block_group
3600 		 */
3601 		spin_lock(&cur_trans->dirty_bgs_lock);
3602 		list_del_init(&cache->dirty_list);
3603 		spin_unlock(&cur_trans->dirty_bgs_lock);
3604 
3605 		should_put = 1;
3606 
3607 		cache_save_setup(cache, trans, path);
3608 
3609 		if (cache->disk_cache_state == BTRFS_DC_SETUP) {
3610 			cache->io_ctl.inode = NULL;
3611 			ret = btrfs_write_out_cache(fs_info, trans,
3612 						    cache, path);
3613 			if (ret == 0 && cache->io_ctl.inode) {
3614 				num_started++;
3615 				should_put = 0;
3616 
3617 				/*
3618 				 * the cache_write_mutex is protecting
3619 				 * the io_list
3620 				 */
3621 				list_add_tail(&cache->io_list, io);
3622 			} else {
3623 				/*
3624 				 * if we failed to write the cache, the
3625 				 * generation will be bad and life goes on
3626 				 */
3627 				ret = 0;
3628 			}
3629 		}
3630 		if (!ret) {
3631 			ret = write_one_cache_group(trans, fs_info,
3632 						    path, cache);
3633 			/*
3634 			 * Our block group might still be attached to the list
3635 			 * of new block groups in the transaction handle of some
3636 			 * other task (struct btrfs_trans_handle->new_bgs). This
3637 			 * means its block group item isn't yet in the extent
3638 			 * tree. If this happens ignore the error, as we will
3639 			 * try again later in the critical section of the
3640 			 * transaction commit.
3641 			 */
3642 			if (ret == -ENOENT) {
3643 				ret = 0;
3644 				spin_lock(&cur_trans->dirty_bgs_lock);
3645 				if (list_empty(&cache->dirty_list)) {
3646 					list_add_tail(&cache->dirty_list,
3647 						      &cur_trans->dirty_bgs);
3648 					btrfs_get_block_group(cache);
3649 				}
3650 				spin_unlock(&cur_trans->dirty_bgs_lock);
3651 			} else if (ret) {
3652 				btrfs_abort_transaction(trans, ret);
3653 			}
3654 		}
3655 
3656 		/* if its not on the io list, we need to put the block group */
3657 		if (should_put)
3658 			btrfs_put_block_group(cache);
3659 
3660 		if (ret)
3661 			break;
3662 
3663 		/*
3664 		 * Avoid blocking other tasks for too long. It might even save
3665 		 * us from writing caches for block groups that are going to be
3666 		 * removed.
3667 		 */
3668 		mutex_unlock(&trans->transaction->cache_write_mutex);
3669 		mutex_lock(&trans->transaction->cache_write_mutex);
3670 	}
3671 	mutex_unlock(&trans->transaction->cache_write_mutex);
3672 
3673 	/*
3674 	 * go through delayed refs for all the stuff we've just kicked off
3675 	 * and then loop back (just once)
3676 	 */
3677 	ret = btrfs_run_delayed_refs(trans, fs_info, 0);
3678 	if (!ret && loops == 0) {
3679 		loops++;
3680 		spin_lock(&cur_trans->dirty_bgs_lock);
3681 		list_splice_init(&cur_trans->dirty_bgs, &dirty);
3682 		/*
3683 		 * dirty_bgs_lock protects us from concurrent block group
3684 		 * deletes too (not just cache_write_mutex).
3685 		 */
3686 		if (!list_empty(&dirty)) {
3687 			spin_unlock(&cur_trans->dirty_bgs_lock);
3688 			goto again;
3689 		}
3690 		spin_unlock(&cur_trans->dirty_bgs_lock);
3691 	} else if (ret < 0) {
3692 		btrfs_cleanup_dirty_bgs(cur_trans, fs_info);
3693 	}
3694 
3695 	btrfs_free_path(path);
3696 	return ret;
3697 }
3698 
3699 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
3700 				   struct btrfs_fs_info *fs_info)
3701 {
3702 	struct btrfs_block_group_cache *cache;
3703 	struct btrfs_transaction *cur_trans = trans->transaction;
3704 	int ret = 0;
3705 	int should_put;
3706 	struct btrfs_path *path;
3707 	struct list_head *io = &cur_trans->io_bgs;
3708 	int num_started = 0;
3709 
3710 	path = btrfs_alloc_path();
3711 	if (!path)
3712 		return -ENOMEM;
3713 
3714 	/*
3715 	 * Even though we are in the critical section of the transaction commit,
3716 	 * we can still have concurrent tasks adding elements to this
3717 	 * transaction's list of dirty block groups. These tasks correspond to
3718 	 * endio free space workers started when writeback finishes for a
3719 	 * space cache, which run inode.c:btrfs_finish_ordered_io(), and can
3720 	 * allocate new block groups as a result of COWing nodes of the root
3721 	 * tree when updating the free space inode. The writeback for the space
3722 	 * caches is triggered by an earlier call to
3723 	 * btrfs_start_dirty_block_groups() and iterations of the following
3724 	 * loop.
3725 	 * Also we want to do the cache_save_setup first and then run the
3726 	 * delayed refs to make sure we have the best chance at doing this all
3727 	 * in one shot.
3728 	 */
3729 	spin_lock(&cur_trans->dirty_bgs_lock);
3730 	while (!list_empty(&cur_trans->dirty_bgs)) {
3731 		cache = list_first_entry(&cur_trans->dirty_bgs,
3732 					 struct btrfs_block_group_cache,
3733 					 dirty_list);
3734 
3735 		/*
3736 		 * this can happen if cache_save_setup re-dirties a block
3737 		 * group that is already under IO.  Just wait for it to
3738 		 * finish and then do it all again
3739 		 */
3740 		if (!list_empty(&cache->io_list)) {
3741 			spin_unlock(&cur_trans->dirty_bgs_lock);
3742 			list_del_init(&cache->io_list);
3743 			btrfs_wait_cache_io(trans, cache, path);
3744 			btrfs_put_block_group(cache);
3745 			spin_lock(&cur_trans->dirty_bgs_lock);
3746 		}
3747 
3748 		/*
3749 		 * don't remove from the dirty list until after we've waited
3750 		 * on any pending IO
3751 		 */
3752 		list_del_init(&cache->dirty_list);
3753 		spin_unlock(&cur_trans->dirty_bgs_lock);
3754 		should_put = 1;
3755 
3756 		cache_save_setup(cache, trans, path);
3757 
3758 		if (!ret)
3759 			ret = btrfs_run_delayed_refs(trans, fs_info,
3760 						     (unsigned long) -1);
3761 
3762 		if (!ret && cache->disk_cache_state == BTRFS_DC_SETUP) {
3763 			cache->io_ctl.inode = NULL;
3764 			ret = btrfs_write_out_cache(fs_info, trans,
3765 						    cache, path);
3766 			if (ret == 0 && cache->io_ctl.inode) {
3767 				num_started++;
3768 				should_put = 0;
3769 				list_add_tail(&cache->io_list, io);
3770 			} else {
3771 				/*
3772 				 * if we failed to write the cache, the
3773 				 * generation will be bad and life goes on
3774 				 */
3775 				ret = 0;
3776 			}
3777 		}
3778 		if (!ret) {
3779 			ret = write_one_cache_group(trans, fs_info,
3780 						    path, cache);
3781 			/*
3782 			 * One of the free space endio workers might have
3783 			 * created a new block group while updating a free space
3784 			 * cache's inode (at inode.c:btrfs_finish_ordered_io())
3785 			 * and hasn't released its transaction handle yet, in
3786 			 * which case the new block group is still attached to
3787 			 * its transaction handle and its creation has not
3788 			 * finished yet (no block group item in the extent tree
3789 			 * yet, etc). If this is the case, wait for all free
3790 			 * space endio workers to finish and retry. This is a
3791 			 * a very rare case so no need for a more efficient and
3792 			 * complex approach.
3793 			 */
3794 			if (ret == -ENOENT) {
3795 				wait_event(cur_trans->writer_wait,
3796 				   atomic_read(&cur_trans->num_writers) == 1);
3797 				ret = write_one_cache_group(trans, fs_info,
3798 							    path, cache);
3799 			}
3800 			if (ret)
3801 				btrfs_abort_transaction(trans, ret);
3802 		}
3803 
3804 		/* if its not on the io list, we need to put the block group */
3805 		if (should_put)
3806 			btrfs_put_block_group(cache);
3807 		spin_lock(&cur_trans->dirty_bgs_lock);
3808 	}
3809 	spin_unlock(&cur_trans->dirty_bgs_lock);
3810 
3811 	while (!list_empty(io)) {
3812 		cache = list_first_entry(io, struct btrfs_block_group_cache,
3813 					 io_list);
3814 		list_del_init(&cache->io_list);
3815 		btrfs_wait_cache_io(trans, cache, path);
3816 		btrfs_put_block_group(cache);
3817 	}
3818 
3819 	btrfs_free_path(path);
3820 	return ret;
3821 }
3822 
3823 int btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr)
3824 {
3825 	struct btrfs_block_group_cache *block_group;
3826 	int readonly = 0;
3827 
3828 	block_group = btrfs_lookup_block_group(fs_info, bytenr);
3829 	if (!block_group || block_group->ro)
3830 		readonly = 1;
3831 	if (block_group)
3832 		btrfs_put_block_group(block_group);
3833 	return readonly;
3834 }
3835 
3836 bool btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr)
3837 {
3838 	struct btrfs_block_group_cache *bg;
3839 	bool ret = true;
3840 
3841 	bg = btrfs_lookup_block_group(fs_info, bytenr);
3842 	if (!bg)
3843 		return false;
3844 
3845 	spin_lock(&bg->lock);
3846 	if (bg->ro)
3847 		ret = false;
3848 	else
3849 		atomic_inc(&bg->nocow_writers);
3850 	spin_unlock(&bg->lock);
3851 
3852 	/* no put on block group, done by btrfs_dec_nocow_writers */
3853 	if (!ret)
3854 		btrfs_put_block_group(bg);
3855 
3856 	return ret;
3857 
3858 }
3859 
3860 void btrfs_dec_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr)
3861 {
3862 	struct btrfs_block_group_cache *bg;
3863 
3864 	bg = btrfs_lookup_block_group(fs_info, bytenr);
3865 	ASSERT(bg);
3866 	if (atomic_dec_and_test(&bg->nocow_writers))
3867 		wake_up_atomic_t(&bg->nocow_writers);
3868 	/*
3869 	 * Once for our lookup and once for the lookup done by a previous call
3870 	 * to btrfs_inc_nocow_writers()
3871 	 */
3872 	btrfs_put_block_group(bg);
3873 	btrfs_put_block_group(bg);
3874 }
3875 
3876 static int btrfs_wait_nocow_writers_atomic_t(atomic_t *a)
3877 {
3878 	schedule();
3879 	return 0;
3880 }
3881 
3882 void btrfs_wait_nocow_writers(struct btrfs_block_group_cache *bg)
3883 {
3884 	wait_on_atomic_t(&bg->nocow_writers,
3885 			 btrfs_wait_nocow_writers_atomic_t,
3886 			 TASK_UNINTERRUPTIBLE);
3887 }
3888 
3889 static const char *alloc_name(u64 flags)
3890 {
3891 	switch (flags) {
3892 	case BTRFS_BLOCK_GROUP_METADATA|BTRFS_BLOCK_GROUP_DATA:
3893 		return "mixed";
3894 	case BTRFS_BLOCK_GROUP_METADATA:
3895 		return "metadata";
3896 	case BTRFS_BLOCK_GROUP_DATA:
3897 		return "data";
3898 	case BTRFS_BLOCK_GROUP_SYSTEM:
3899 		return "system";
3900 	default:
3901 		WARN_ON(1);
3902 		return "invalid-combination";
3903 	};
3904 }
3905 
3906 static int update_space_info(struct btrfs_fs_info *info, u64 flags,
3907 			     u64 total_bytes, u64 bytes_used,
3908 			     u64 bytes_readonly,
3909 			     struct btrfs_space_info **space_info)
3910 {
3911 	struct btrfs_space_info *found;
3912 	int i;
3913 	int factor;
3914 	int ret;
3915 
3916 	if (flags & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
3917 		     BTRFS_BLOCK_GROUP_RAID10))
3918 		factor = 2;
3919 	else
3920 		factor = 1;
3921 
3922 	found = __find_space_info(info, flags);
3923 	if (found) {
3924 		spin_lock(&found->lock);
3925 		found->total_bytes += total_bytes;
3926 		found->disk_total += total_bytes * factor;
3927 		found->bytes_used += bytes_used;
3928 		found->disk_used += bytes_used * factor;
3929 		found->bytes_readonly += bytes_readonly;
3930 		if (total_bytes > 0)
3931 			found->full = 0;
3932 		space_info_add_new_bytes(info, found, total_bytes -
3933 					 bytes_used - bytes_readonly);
3934 		spin_unlock(&found->lock);
3935 		*space_info = found;
3936 		return 0;
3937 	}
3938 	found = kzalloc(sizeof(*found), GFP_NOFS);
3939 	if (!found)
3940 		return -ENOMEM;
3941 
3942 	ret = percpu_counter_init(&found->total_bytes_pinned, 0, GFP_KERNEL);
3943 	if (ret) {
3944 		kfree(found);
3945 		return ret;
3946 	}
3947 
3948 	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
3949 		INIT_LIST_HEAD(&found->block_groups[i]);
3950 	init_rwsem(&found->groups_sem);
3951 	spin_lock_init(&found->lock);
3952 	found->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
3953 	found->total_bytes = total_bytes;
3954 	found->disk_total = total_bytes * factor;
3955 	found->bytes_used = bytes_used;
3956 	found->disk_used = bytes_used * factor;
3957 	found->bytes_pinned = 0;
3958 	found->bytes_reserved = 0;
3959 	found->bytes_readonly = bytes_readonly;
3960 	found->bytes_may_use = 0;
3961 	found->full = 0;
3962 	found->max_extent_size = 0;
3963 	found->force_alloc = CHUNK_ALLOC_NO_FORCE;
3964 	found->chunk_alloc = 0;
3965 	found->flush = 0;
3966 	init_waitqueue_head(&found->wait);
3967 	INIT_LIST_HEAD(&found->ro_bgs);
3968 	INIT_LIST_HEAD(&found->tickets);
3969 	INIT_LIST_HEAD(&found->priority_tickets);
3970 
3971 	ret = kobject_init_and_add(&found->kobj, &space_info_ktype,
3972 				    info->space_info_kobj, "%s",
3973 				    alloc_name(found->flags));
3974 	if (ret) {
3975 		kfree(found);
3976 		return ret;
3977 	}
3978 
3979 	*space_info = found;
3980 	list_add_rcu(&found->list, &info->space_info);
3981 	if (flags & BTRFS_BLOCK_GROUP_DATA)
3982 		info->data_sinfo = found;
3983 
3984 	return ret;
3985 }
3986 
3987 static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
3988 {
3989 	u64 extra_flags = chunk_to_extended(flags) &
3990 				BTRFS_EXTENDED_PROFILE_MASK;
3991 
3992 	write_seqlock(&fs_info->profiles_lock);
3993 	if (flags & BTRFS_BLOCK_GROUP_DATA)
3994 		fs_info->avail_data_alloc_bits |= extra_flags;
3995 	if (flags & BTRFS_BLOCK_GROUP_METADATA)
3996 		fs_info->avail_metadata_alloc_bits |= extra_flags;
3997 	if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
3998 		fs_info->avail_system_alloc_bits |= extra_flags;
3999 	write_sequnlock(&fs_info->profiles_lock);
4000 }
4001 
4002 /*
4003  * returns target flags in extended format or 0 if restripe for this
4004  * chunk_type is not in progress
4005  *
4006  * should be called with either volume_mutex or balance_lock held
4007  */
4008 static u64 get_restripe_target(struct btrfs_fs_info *fs_info, u64 flags)
4009 {
4010 	struct btrfs_balance_control *bctl = fs_info->balance_ctl;
4011 	u64 target = 0;
4012 
4013 	if (!bctl)
4014 		return 0;
4015 
4016 	if (flags & BTRFS_BLOCK_GROUP_DATA &&
4017 	    bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) {
4018 		target = BTRFS_BLOCK_GROUP_DATA | bctl->data.target;
4019 	} else if (flags & BTRFS_BLOCK_GROUP_SYSTEM &&
4020 		   bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
4021 		target = BTRFS_BLOCK_GROUP_SYSTEM | bctl->sys.target;
4022 	} else if (flags & BTRFS_BLOCK_GROUP_METADATA &&
4023 		   bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) {
4024 		target = BTRFS_BLOCK_GROUP_METADATA | bctl->meta.target;
4025 	}
4026 
4027 	return target;
4028 }
4029 
4030 /*
4031  * @flags: available profiles in extended format (see ctree.h)
4032  *
4033  * Returns reduced profile in chunk format.  If profile changing is in
4034  * progress (either running or paused) picks the target profile (if it's
4035  * already available), otherwise falls back to plain reducing.
4036  */
4037 static u64 btrfs_reduce_alloc_profile(struct btrfs_fs_info *fs_info, u64 flags)
4038 {
4039 	u64 num_devices = fs_info->fs_devices->rw_devices;
4040 	u64 target;
4041 	u64 raid_type;
4042 	u64 allowed = 0;
4043 
4044 	/*
4045 	 * see if restripe for this chunk_type is in progress, if so
4046 	 * try to reduce to the target profile
4047 	 */
4048 	spin_lock(&fs_info->balance_lock);
4049 	target = get_restripe_target(fs_info, flags);
4050 	if (target) {
4051 		/* pick target profile only if it's already available */
4052 		if ((flags & target) & BTRFS_EXTENDED_PROFILE_MASK) {
4053 			spin_unlock(&fs_info->balance_lock);
4054 			return extended_to_chunk(target);
4055 		}
4056 	}
4057 	spin_unlock(&fs_info->balance_lock);
4058 
4059 	/* First, mask out the RAID levels which aren't possible */
4060 	for (raid_type = 0; raid_type < BTRFS_NR_RAID_TYPES; raid_type++) {
4061 		if (num_devices >= btrfs_raid_array[raid_type].devs_min)
4062 			allowed |= btrfs_raid_group[raid_type];
4063 	}
4064 	allowed &= flags;
4065 
4066 	if (allowed & BTRFS_BLOCK_GROUP_RAID6)
4067 		allowed = BTRFS_BLOCK_GROUP_RAID6;
4068 	else if (allowed & BTRFS_BLOCK_GROUP_RAID5)
4069 		allowed = BTRFS_BLOCK_GROUP_RAID5;
4070 	else if (allowed & BTRFS_BLOCK_GROUP_RAID10)
4071 		allowed = BTRFS_BLOCK_GROUP_RAID10;
4072 	else if (allowed & BTRFS_BLOCK_GROUP_RAID1)
4073 		allowed = BTRFS_BLOCK_GROUP_RAID1;
4074 	else if (allowed & BTRFS_BLOCK_GROUP_RAID0)
4075 		allowed = BTRFS_BLOCK_GROUP_RAID0;
4076 
4077 	flags &= ~BTRFS_BLOCK_GROUP_PROFILE_MASK;
4078 
4079 	return extended_to_chunk(flags | allowed);
4080 }
4081 
4082 static u64 get_alloc_profile(struct btrfs_fs_info *fs_info, u64 orig_flags)
4083 {
4084 	unsigned seq;
4085 	u64 flags;
4086 
4087 	do {
4088 		flags = orig_flags;
4089 		seq = read_seqbegin(&fs_info->profiles_lock);
4090 
4091 		if (flags & BTRFS_BLOCK_GROUP_DATA)
4092 			flags |= fs_info->avail_data_alloc_bits;
4093 		else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
4094 			flags |= fs_info->avail_system_alloc_bits;
4095 		else if (flags & BTRFS_BLOCK_GROUP_METADATA)
4096 			flags |= fs_info->avail_metadata_alloc_bits;
4097 	} while (read_seqretry(&fs_info->profiles_lock, seq));
4098 
4099 	return btrfs_reduce_alloc_profile(fs_info, flags);
4100 }
4101 
4102 u64 btrfs_get_alloc_profile(struct btrfs_root *root, int data)
4103 {
4104 	struct btrfs_fs_info *fs_info = root->fs_info;
4105 	u64 flags;
4106 	u64 ret;
4107 
4108 	if (data)
4109 		flags = BTRFS_BLOCK_GROUP_DATA;
4110 	else if (root == fs_info->chunk_root)
4111 		flags = BTRFS_BLOCK_GROUP_SYSTEM;
4112 	else
4113 		flags = BTRFS_BLOCK_GROUP_METADATA;
4114 
4115 	ret = get_alloc_profile(fs_info, flags);
4116 	return ret;
4117 }
4118 
4119 int btrfs_alloc_data_chunk_ondemand(struct inode *inode, u64 bytes)
4120 {
4121 	struct btrfs_space_info *data_sinfo;
4122 	struct btrfs_root *root = BTRFS_I(inode)->root;
4123 	struct btrfs_fs_info *fs_info = root->fs_info;
4124 	u64 used;
4125 	int ret = 0;
4126 	int need_commit = 2;
4127 	int have_pinned_space;
4128 
4129 	/* make sure bytes are sectorsize aligned */
4130 	bytes = ALIGN(bytes, fs_info->sectorsize);
4131 
4132 	if (btrfs_is_free_space_inode(inode)) {
4133 		need_commit = 0;
4134 		ASSERT(current->journal_info);
4135 	}
4136 
4137 	data_sinfo = fs_info->data_sinfo;
4138 	if (!data_sinfo)
4139 		goto alloc;
4140 
4141 again:
4142 	/* make sure we have enough space to handle the data first */
4143 	spin_lock(&data_sinfo->lock);
4144 	used = data_sinfo->bytes_used + data_sinfo->bytes_reserved +
4145 		data_sinfo->bytes_pinned + data_sinfo->bytes_readonly +
4146 		data_sinfo->bytes_may_use;
4147 
4148 	if (used + bytes > data_sinfo->total_bytes) {
4149 		struct btrfs_trans_handle *trans;
4150 
4151 		/*
4152 		 * if we don't have enough free bytes in this space then we need
4153 		 * to alloc a new chunk.
4154 		 */
4155 		if (!data_sinfo->full) {
4156 			u64 alloc_target;
4157 
4158 			data_sinfo->force_alloc = CHUNK_ALLOC_FORCE;
4159 			spin_unlock(&data_sinfo->lock);
4160 alloc:
4161 			alloc_target = btrfs_get_alloc_profile(root, 1);
4162 			/*
4163 			 * It is ugly that we don't call nolock join
4164 			 * transaction for the free space inode case here.
4165 			 * But it is safe because we only do the data space
4166 			 * reservation for the free space cache in the
4167 			 * transaction context, the common join transaction
4168 			 * just increase the counter of the current transaction
4169 			 * handler, doesn't try to acquire the trans_lock of
4170 			 * the fs.
4171 			 */
4172 			trans = btrfs_join_transaction(root);
4173 			if (IS_ERR(trans))
4174 				return PTR_ERR(trans);
4175 
4176 			ret = do_chunk_alloc(trans, fs_info, alloc_target,
4177 					     CHUNK_ALLOC_NO_FORCE);
4178 			btrfs_end_transaction(trans);
4179 			if (ret < 0) {
4180 				if (ret != -ENOSPC)
4181 					return ret;
4182 				else {
4183 					have_pinned_space = 1;
4184 					goto commit_trans;
4185 				}
4186 			}
4187 
4188 			if (!data_sinfo)
4189 				data_sinfo = fs_info->data_sinfo;
4190 
4191 			goto again;
4192 		}
4193 
4194 		/*
4195 		 * If we don't have enough pinned space to deal with this
4196 		 * allocation, and no removed chunk in current transaction,
4197 		 * don't bother committing the transaction.
4198 		 */
4199 		have_pinned_space = percpu_counter_compare(
4200 			&data_sinfo->total_bytes_pinned,
4201 			used + bytes - data_sinfo->total_bytes);
4202 		spin_unlock(&data_sinfo->lock);
4203 
4204 		/* commit the current transaction and try again */
4205 commit_trans:
4206 		if (need_commit &&
4207 		    !atomic_read(&fs_info->open_ioctl_trans)) {
4208 			need_commit--;
4209 
4210 			if (need_commit > 0) {
4211 				btrfs_start_delalloc_roots(fs_info, 0, -1);
4212 				btrfs_wait_ordered_roots(fs_info, -1, 0,
4213 							 (u64)-1);
4214 			}
4215 
4216 			trans = btrfs_join_transaction(root);
4217 			if (IS_ERR(trans))
4218 				return PTR_ERR(trans);
4219 			if (have_pinned_space >= 0 ||
4220 			    test_bit(BTRFS_TRANS_HAVE_FREE_BGS,
4221 				     &trans->transaction->flags) ||
4222 			    need_commit > 0) {
4223 				ret = btrfs_commit_transaction(trans);
4224 				if (ret)
4225 					return ret;
4226 				/*
4227 				 * The cleaner kthread might still be doing iput
4228 				 * operations. Wait for it to finish so that
4229 				 * more space is released.
4230 				 */
4231 				mutex_lock(&fs_info->cleaner_delayed_iput_mutex);
4232 				mutex_unlock(&fs_info->cleaner_delayed_iput_mutex);
4233 				goto again;
4234 			} else {
4235 				btrfs_end_transaction(trans);
4236 			}
4237 		}
4238 
4239 		trace_btrfs_space_reservation(fs_info,
4240 					      "space_info:enospc",
4241 					      data_sinfo->flags, bytes, 1);
4242 		return -ENOSPC;
4243 	}
4244 	data_sinfo->bytes_may_use += bytes;
4245 	trace_btrfs_space_reservation(fs_info, "space_info",
4246 				      data_sinfo->flags, bytes, 1);
4247 	spin_unlock(&data_sinfo->lock);
4248 
4249 	return ret;
4250 }
4251 
4252 /*
4253  * New check_data_free_space() with ability for precious data reservation
4254  * Will replace old btrfs_check_data_free_space(), but for patch split,
4255  * add a new function first and then replace it.
4256  */
4257 int btrfs_check_data_free_space(struct inode *inode, u64 start, u64 len)
4258 {
4259 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4260 	int ret;
4261 
4262 	/* align the range */
4263 	len = round_up(start + len, fs_info->sectorsize) -
4264 	      round_down(start, fs_info->sectorsize);
4265 	start = round_down(start, fs_info->sectorsize);
4266 
4267 	ret = btrfs_alloc_data_chunk_ondemand(inode, len);
4268 	if (ret < 0)
4269 		return ret;
4270 
4271 	/* Use new btrfs_qgroup_reserve_data to reserve precious data space. */
4272 	ret = btrfs_qgroup_reserve_data(inode, start, len);
4273 	if (ret)
4274 		btrfs_free_reserved_data_space_noquota(inode, start, len);
4275 	return ret;
4276 }
4277 
4278 /*
4279  * Called if we need to clear a data reservation for this inode
4280  * Normally in a error case.
4281  *
4282  * This one will *NOT* use accurate qgroup reserved space API, just for case
4283  * which we can't sleep and is sure it won't affect qgroup reserved space.
4284  * Like clear_bit_hook().
4285  */
4286 void btrfs_free_reserved_data_space_noquota(struct inode *inode, u64 start,
4287 					    u64 len)
4288 {
4289 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4290 	struct btrfs_space_info *data_sinfo;
4291 
4292 	/* Make sure the range is aligned to sectorsize */
4293 	len = round_up(start + len, fs_info->sectorsize) -
4294 	      round_down(start, fs_info->sectorsize);
4295 	start = round_down(start, fs_info->sectorsize);
4296 
4297 	data_sinfo = fs_info->data_sinfo;
4298 	spin_lock(&data_sinfo->lock);
4299 	if (WARN_ON(data_sinfo->bytes_may_use < len))
4300 		data_sinfo->bytes_may_use = 0;
4301 	else
4302 		data_sinfo->bytes_may_use -= len;
4303 	trace_btrfs_space_reservation(fs_info, "space_info",
4304 				      data_sinfo->flags, len, 0);
4305 	spin_unlock(&data_sinfo->lock);
4306 }
4307 
4308 /*
4309  * Called if we need to clear a data reservation for this inode
4310  * Normally in a error case.
4311  *
4312  * This one will handle the per-inode data rsv map for accurate reserved
4313  * space framework.
4314  */
4315 void btrfs_free_reserved_data_space(struct inode *inode, u64 start, u64 len)
4316 {
4317 	struct btrfs_root *root = BTRFS_I(inode)->root;
4318 
4319 	/* Make sure the range is aligned to sectorsize */
4320 	len = round_up(start + len, root->fs_info->sectorsize) -
4321 	      round_down(start, root->fs_info->sectorsize);
4322 	start = round_down(start, root->fs_info->sectorsize);
4323 
4324 	btrfs_free_reserved_data_space_noquota(inode, start, len);
4325 	btrfs_qgroup_free_data(inode, start, len);
4326 }
4327 
4328 static void force_metadata_allocation(struct btrfs_fs_info *info)
4329 {
4330 	struct list_head *head = &info->space_info;
4331 	struct btrfs_space_info *found;
4332 
4333 	rcu_read_lock();
4334 	list_for_each_entry_rcu(found, head, list) {
4335 		if (found->flags & BTRFS_BLOCK_GROUP_METADATA)
4336 			found->force_alloc = CHUNK_ALLOC_FORCE;
4337 	}
4338 	rcu_read_unlock();
4339 }
4340 
4341 static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
4342 {
4343 	return (global->size << 1);
4344 }
4345 
4346 static int should_alloc_chunk(struct btrfs_fs_info *fs_info,
4347 			      struct btrfs_space_info *sinfo, int force)
4348 {
4349 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
4350 	u64 num_bytes = sinfo->total_bytes - sinfo->bytes_readonly;
4351 	u64 num_allocated = sinfo->bytes_used + sinfo->bytes_reserved;
4352 	u64 thresh;
4353 
4354 	if (force == CHUNK_ALLOC_FORCE)
4355 		return 1;
4356 
4357 	/*
4358 	 * We need to take into account the global rsv because for all intents
4359 	 * and purposes it's used space.  Don't worry about locking the
4360 	 * global_rsv, it doesn't change except when the transaction commits.
4361 	 */
4362 	if (sinfo->flags & BTRFS_BLOCK_GROUP_METADATA)
4363 		num_allocated += calc_global_rsv_need_space(global_rsv);
4364 
4365 	/*
4366 	 * in limited mode, we want to have some free space up to
4367 	 * about 1% of the FS size.
4368 	 */
4369 	if (force == CHUNK_ALLOC_LIMITED) {
4370 		thresh = btrfs_super_total_bytes(fs_info->super_copy);
4371 		thresh = max_t(u64, SZ_64M, div_factor_fine(thresh, 1));
4372 
4373 		if (num_bytes - num_allocated < thresh)
4374 			return 1;
4375 	}
4376 
4377 	if (num_allocated + SZ_2M < div_factor(num_bytes, 8))
4378 		return 0;
4379 	return 1;
4380 }
4381 
4382 static u64 get_profile_num_devs(struct btrfs_fs_info *fs_info, u64 type)
4383 {
4384 	u64 num_dev;
4385 
4386 	if (type & (BTRFS_BLOCK_GROUP_RAID10 |
4387 		    BTRFS_BLOCK_GROUP_RAID0 |
4388 		    BTRFS_BLOCK_GROUP_RAID5 |
4389 		    BTRFS_BLOCK_GROUP_RAID6))
4390 		num_dev = fs_info->fs_devices->rw_devices;
4391 	else if (type & BTRFS_BLOCK_GROUP_RAID1)
4392 		num_dev = 2;
4393 	else
4394 		num_dev = 1;	/* DUP or single */
4395 
4396 	return num_dev;
4397 }
4398 
4399 /*
4400  * If @is_allocation is true, reserve space in the system space info necessary
4401  * for allocating a chunk, otherwise if it's false, reserve space necessary for
4402  * removing a chunk.
4403  */
4404 void check_system_chunk(struct btrfs_trans_handle *trans,
4405 			struct btrfs_fs_info *fs_info, u64 type)
4406 {
4407 	struct btrfs_space_info *info;
4408 	u64 left;
4409 	u64 thresh;
4410 	int ret = 0;
4411 	u64 num_devs;
4412 
4413 	/*
4414 	 * Needed because we can end up allocating a system chunk and for an
4415 	 * atomic and race free space reservation in the chunk block reserve.
4416 	 */
4417 	ASSERT(mutex_is_locked(&fs_info->chunk_mutex));
4418 
4419 	info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
4420 	spin_lock(&info->lock);
4421 	left = info->total_bytes - info->bytes_used - info->bytes_pinned -
4422 		info->bytes_reserved - info->bytes_readonly -
4423 		info->bytes_may_use;
4424 	spin_unlock(&info->lock);
4425 
4426 	num_devs = get_profile_num_devs(fs_info, type);
4427 
4428 	/* num_devs device items to update and 1 chunk item to add or remove */
4429 	thresh = btrfs_calc_trunc_metadata_size(fs_info, num_devs) +
4430 		btrfs_calc_trans_metadata_size(fs_info, 1);
4431 
4432 	if (left < thresh && btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
4433 		btrfs_info(fs_info, "left=%llu, need=%llu, flags=%llu",
4434 			   left, thresh, type);
4435 		dump_space_info(fs_info, info, 0, 0);
4436 	}
4437 
4438 	if (left < thresh) {
4439 		u64 flags;
4440 
4441 		flags = btrfs_get_alloc_profile(fs_info->chunk_root, 0);
4442 		/*
4443 		 * Ignore failure to create system chunk. We might end up not
4444 		 * needing it, as we might not need to COW all nodes/leafs from
4445 		 * the paths we visit in the chunk tree (they were already COWed
4446 		 * or created in the current transaction for example).
4447 		 */
4448 		ret = btrfs_alloc_chunk(trans, fs_info, flags);
4449 	}
4450 
4451 	if (!ret) {
4452 		ret = btrfs_block_rsv_add(fs_info->chunk_root,
4453 					  &fs_info->chunk_block_rsv,
4454 					  thresh, BTRFS_RESERVE_NO_FLUSH);
4455 		if (!ret)
4456 			trans->chunk_bytes_reserved += thresh;
4457 	}
4458 }
4459 
4460 /*
4461  * If force is CHUNK_ALLOC_FORCE:
4462  *    - return 1 if it successfully allocates a chunk,
4463  *    - return errors including -ENOSPC otherwise.
4464  * If force is NOT CHUNK_ALLOC_FORCE:
4465  *    - return 0 if it doesn't need to allocate a new chunk,
4466  *    - return 1 if it successfully allocates a chunk,
4467  *    - return errors including -ENOSPC otherwise.
4468  */
4469 static int do_chunk_alloc(struct btrfs_trans_handle *trans,
4470 			  struct btrfs_fs_info *fs_info, u64 flags, int force)
4471 {
4472 	struct btrfs_space_info *space_info;
4473 	int wait_for_alloc = 0;
4474 	int ret = 0;
4475 
4476 	/* Don't re-enter if we're already allocating a chunk */
4477 	if (trans->allocating_chunk)
4478 		return -ENOSPC;
4479 
4480 	space_info = __find_space_info(fs_info, flags);
4481 	if (!space_info) {
4482 		ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
4483 		BUG_ON(ret); /* -ENOMEM */
4484 	}
4485 	BUG_ON(!space_info); /* Logic error */
4486 
4487 again:
4488 	spin_lock(&space_info->lock);
4489 	if (force < space_info->force_alloc)
4490 		force = space_info->force_alloc;
4491 	if (space_info->full) {
4492 		if (should_alloc_chunk(fs_info, space_info, force))
4493 			ret = -ENOSPC;
4494 		else
4495 			ret = 0;
4496 		spin_unlock(&space_info->lock);
4497 		return ret;
4498 	}
4499 
4500 	if (!should_alloc_chunk(fs_info, space_info, force)) {
4501 		spin_unlock(&space_info->lock);
4502 		return 0;
4503 	} else if (space_info->chunk_alloc) {
4504 		wait_for_alloc = 1;
4505 	} else {
4506 		space_info->chunk_alloc = 1;
4507 	}
4508 
4509 	spin_unlock(&space_info->lock);
4510 
4511 	mutex_lock(&fs_info->chunk_mutex);
4512 
4513 	/*
4514 	 * The chunk_mutex is held throughout the entirety of a chunk
4515 	 * allocation, so once we've acquired the chunk_mutex we know that the
4516 	 * other guy is done and we need to recheck and see if we should
4517 	 * allocate.
4518 	 */
4519 	if (wait_for_alloc) {
4520 		mutex_unlock(&fs_info->chunk_mutex);
4521 		wait_for_alloc = 0;
4522 		goto again;
4523 	}
4524 
4525 	trans->allocating_chunk = true;
4526 
4527 	/*
4528 	 * If we have mixed data/metadata chunks we want to make sure we keep
4529 	 * allocating mixed chunks instead of individual chunks.
4530 	 */
4531 	if (btrfs_mixed_space_info(space_info))
4532 		flags |= (BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA);
4533 
4534 	/*
4535 	 * if we're doing a data chunk, go ahead and make sure that
4536 	 * we keep a reasonable number of metadata chunks allocated in the
4537 	 * FS as well.
4538 	 */
4539 	if (flags & BTRFS_BLOCK_GROUP_DATA && fs_info->metadata_ratio) {
4540 		fs_info->data_chunk_allocations++;
4541 		if (!(fs_info->data_chunk_allocations %
4542 		      fs_info->metadata_ratio))
4543 			force_metadata_allocation(fs_info);
4544 	}
4545 
4546 	/*
4547 	 * Check if we have enough space in SYSTEM chunk because we may need
4548 	 * to update devices.
4549 	 */
4550 	check_system_chunk(trans, fs_info, flags);
4551 
4552 	ret = btrfs_alloc_chunk(trans, fs_info, flags);
4553 	trans->allocating_chunk = false;
4554 
4555 	spin_lock(&space_info->lock);
4556 	if (ret < 0 && ret != -ENOSPC)
4557 		goto out;
4558 	if (ret)
4559 		space_info->full = 1;
4560 	else
4561 		ret = 1;
4562 
4563 	space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
4564 out:
4565 	space_info->chunk_alloc = 0;
4566 	spin_unlock(&space_info->lock);
4567 	mutex_unlock(&fs_info->chunk_mutex);
4568 	/*
4569 	 * When we allocate a new chunk we reserve space in the chunk block
4570 	 * reserve to make sure we can COW nodes/leafs in the chunk tree or
4571 	 * add new nodes/leafs to it if we end up needing to do it when
4572 	 * inserting the chunk item and updating device items as part of the
4573 	 * second phase of chunk allocation, performed by
4574 	 * btrfs_finish_chunk_alloc(). So make sure we don't accumulate a
4575 	 * large number of new block groups to create in our transaction
4576 	 * handle's new_bgs list to avoid exhausting the chunk block reserve
4577 	 * in extreme cases - like having a single transaction create many new
4578 	 * block groups when starting to write out the free space caches of all
4579 	 * the block groups that were made dirty during the lifetime of the
4580 	 * transaction.
4581 	 */
4582 	if (trans->can_flush_pending_bgs &&
4583 	    trans->chunk_bytes_reserved >= (u64)SZ_2M) {
4584 		btrfs_create_pending_block_groups(trans, fs_info);
4585 		btrfs_trans_release_chunk_metadata(trans);
4586 	}
4587 	return ret;
4588 }
4589 
4590 static int can_overcommit(struct btrfs_root *root,
4591 			  struct btrfs_space_info *space_info, u64 bytes,
4592 			  enum btrfs_reserve_flush_enum flush)
4593 {
4594 	struct btrfs_fs_info *fs_info = root->fs_info;
4595 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
4596 	u64 profile;
4597 	u64 space_size;
4598 	u64 avail;
4599 	u64 used;
4600 
4601 	/* Don't overcommit when in mixed mode. */
4602 	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
4603 		return 0;
4604 
4605 	profile = btrfs_get_alloc_profile(root, 0);
4606 	used = space_info->bytes_used + space_info->bytes_reserved +
4607 		space_info->bytes_pinned + space_info->bytes_readonly;
4608 
4609 	/*
4610 	 * We only want to allow over committing if we have lots of actual space
4611 	 * free, but if we don't have enough space to handle the global reserve
4612 	 * space then we could end up having a real enospc problem when trying
4613 	 * to allocate a chunk or some other such important allocation.
4614 	 */
4615 	spin_lock(&global_rsv->lock);
4616 	space_size = calc_global_rsv_need_space(global_rsv);
4617 	spin_unlock(&global_rsv->lock);
4618 	if (used + space_size >= space_info->total_bytes)
4619 		return 0;
4620 
4621 	used += space_info->bytes_may_use;
4622 
4623 	spin_lock(&fs_info->free_chunk_lock);
4624 	avail = fs_info->free_chunk_space;
4625 	spin_unlock(&fs_info->free_chunk_lock);
4626 
4627 	/*
4628 	 * If we have dup, raid1 or raid10 then only half of the free
4629 	 * space is actually useable.  For raid56, the space info used
4630 	 * doesn't include the parity drive, so we don't have to
4631 	 * change the math
4632 	 */
4633 	if (profile & (BTRFS_BLOCK_GROUP_DUP |
4634 		       BTRFS_BLOCK_GROUP_RAID1 |
4635 		       BTRFS_BLOCK_GROUP_RAID10))
4636 		avail >>= 1;
4637 
4638 	/*
4639 	 * If we aren't flushing all things, let us overcommit up to
4640 	 * 1/2th of the space. If we can flush, don't let us overcommit
4641 	 * too much, let it overcommit up to 1/8 of the space.
4642 	 */
4643 	if (flush == BTRFS_RESERVE_FLUSH_ALL)
4644 		avail >>= 3;
4645 	else
4646 		avail >>= 1;
4647 
4648 	if (used + bytes < space_info->total_bytes + avail)
4649 		return 1;
4650 	return 0;
4651 }
4652 
4653 static void btrfs_writeback_inodes_sb_nr(struct btrfs_fs_info *fs_info,
4654 					 unsigned long nr_pages, int nr_items)
4655 {
4656 	struct super_block *sb = fs_info->sb;
4657 
4658 	if (down_read_trylock(&sb->s_umount)) {
4659 		writeback_inodes_sb_nr(sb, nr_pages, WB_REASON_FS_FREE_SPACE);
4660 		up_read(&sb->s_umount);
4661 	} else {
4662 		/*
4663 		 * We needn't worry the filesystem going from r/w to r/o though
4664 		 * we don't acquire ->s_umount mutex, because the filesystem
4665 		 * should guarantee the delalloc inodes list be empty after
4666 		 * the filesystem is readonly(all dirty pages are written to
4667 		 * the disk).
4668 		 */
4669 		btrfs_start_delalloc_roots(fs_info, 0, nr_items);
4670 		if (!current->journal_info)
4671 			btrfs_wait_ordered_roots(fs_info, nr_items, 0, (u64)-1);
4672 	}
4673 }
4674 
4675 static inline int calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
4676 					u64 to_reclaim)
4677 {
4678 	u64 bytes;
4679 	int nr;
4680 
4681 	bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
4682 	nr = (int)div64_u64(to_reclaim, bytes);
4683 	if (!nr)
4684 		nr = 1;
4685 	return nr;
4686 }
4687 
4688 #define EXTENT_SIZE_PER_ITEM	SZ_256K
4689 
4690 /*
4691  * shrink metadata reservation for delalloc
4692  */
4693 static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig,
4694 			    bool wait_ordered)
4695 {
4696 	struct btrfs_fs_info *fs_info = root->fs_info;
4697 	struct btrfs_block_rsv *block_rsv;
4698 	struct btrfs_space_info *space_info;
4699 	struct btrfs_trans_handle *trans;
4700 	u64 delalloc_bytes;
4701 	u64 max_reclaim;
4702 	long time_left;
4703 	unsigned long nr_pages;
4704 	int loops;
4705 	int items;
4706 	enum btrfs_reserve_flush_enum flush;
4707 
4708 	/* Calc the number of the pages we need flush for space reservation */
4709 	items = calc_reclaim_items_nr(fs_info, to_reclaim);
4710 	to_reclaim = (u64)items * EXTENT_SIZE_PER_ITEM;
4711 
4712 	trans = (struct btrfs_trans_handle *)current->journal_info;
4713 	block_rsv = &fs_info->delalloc_block_rsv;
4714 	space_info = block_rsv->space_info;
4715 
4716 	delalloc_bytes = percpu_counter_sum_positive(
4717 						&fs_info->delalloc_bytes);
4718 	if (delalloc_bytes == 0) {
4719 		if (trans)
4720 			return;
4721 		if (wait_ordered)
4722 			btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
4723 		return;
4724 	}
4725 
4726 	loops = 0;
4727 	while (delalloc_bytes && loops < 3) {
4728 		max_reclaim = min(delalloc_bytes, to_reclaim);
4729 		nr_pages = max_reclaim >> PAGE_SHIFT;
4730 		btrfs_writeback_inodes_sb_nr(fs_info, nr_pages, items);
4731 		/*
4732 		 * We need to wait for the async pages to actually start before
4733 		 * we do anything.
4734 		 */
4735 		max_reclaim = atomic_read(&fs_info->async_delalloc_pages);
4736 		if (!max_reclaim)
4737 			goto skip_async;
4738 
4739 		if (max_reclaim <= nr_pages)
4740 			max_reclaim = 0;
4741 		else
4742 			max_reclaim -= nr_pages;
4743 
4744 		wait_event(fs_info->async_submit_wait,
4745 			   atomic_read(&fs_info->async_delalloc_pages) <=
4746 			   (int)max_reclaim);
4747 skip_async:
4748 		if (!trans)
4749 			flush = BTRFS_RESERVE_FLUSH_ALL;
4750 		else
4751 			flush = BTRFS_RESERVE_NO_FLUSH;
4752 		spin_lock(&space_info->lock);
4753 		if (can_overcommit(root, space_info, orig, flush)) {
4754 			spin_unlock(&space_info->lock);
4755 			break;
4756 		}
4757 		if (list_empty(&space_info->tickets) &&
4758 		    list_empty(&space_info->priority_tickets)) {
4759 			spin_unlock(&space_info->lock);
4760 			break;
4761 		}
4762 		spin_unlock(&space_info->lock);
4763 
4764 		loops++;
4765 		if (wait_ordered && !trans) {
4766 			btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
4767 		} else {
4768 			time_left = schedule_timeout_killable(1);
4769 			if (time_left)
4770 				break;
4771 		}
4772 		delalloc_bytes = percpu_counter_sum_positive(
4773 						&fs_info->delalloc_bytes);
4774 	}
4775 }
4776 
4777 /**
4778  * maybe_commit_transaction - possibly commit the transaction if its ok to
4779  * @root - the root we're allocating for
4780  * @bytes - the number of bytes we want to reserve
4781  * @force - force the commit
4782  *
4783  * This will check to make sure that committing the transaction will actually
4784  * get us somewhere and then commit the transaction if it does.  Otherwise it
4785  * will return -ENOSPC.
4786  */
4787 static int may_commit_transaction(struct btrfs_root *root,
4788 				  struct btrfs_space_info *space_info,
4789 				  u64 bytes, int force)
4790 {
4791 	struct btrfs_fs_info *fs_info = root->fs_info;
4792 	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_block_rsv;
4793 	struct btrfs_trans_handle *trans;
4794 
4795 	trans = (struct btrfs_trans_handle *)current->journal_info;
4796 	if (trans)
4797 		return -EAGAIN;
4798 
4799 	if (force)
4800 		goto commit;
4801 
4802 	/* See if there is enough pinned space to make this reservation */
4803 	if (percpu_counter_compare(&space_info->total_bytes_pinned,
4804 				   bytes) >= 0)
4805 		goto commit;
4806 
4807 	/*
4808 	 * See if there is some space in the delayed insertion reservation for
4809 	 * this reservation.
4810 	 */
4811 	if (space_info != delayed_rsv->space_info)
4812 		return -ENOSPC;
4813 
4814 	spin_lock(&delayed_rsv->lock);
4815 	if (percpu_counter_compare(&space_info->total_bytes_pinned,
4816 				   bytes - delayed_rsv->size) >= 0) {
4817 		spin_unlock(&delayed_rsv->lock);
4818 		return -ENOSPC;
4819 	}
4820 	spin_unlock(&delayed_rsv->lock);
4821 
4822 commit:
4823 	trans = btrfs_join_transaction(root);
4824 	if (IS_ERR(trans))
4825 		return -ENOSPC;
4826 
4827 	return btrfs_commit_transaction(trans);
4828 }
4829 
4830 struct reserve_ticket {
4831 	u64 bytes;
4832 	int error;
4833 	struct list_head list;
4834 	wait_queue_head_t wait;
4835 };
4836 
4837 static int flush_space(struct btrfs_root *root,
4838 		       struct btrfs_space_info *space_info, u64 num_bytes,
4839 		       u64 orig_bytes, int state)
4840 {
4841 	struct btrfs_fs_info *fs_info = root->fs_info;
4842 	struct btrfs_trans_handle *trans;
4843 	int nr;
4844 	int ret = 0;
4845 
4846 	switch (state) {
4847 	case FLUSH_DELAYED_ITEMS_NR:
4848 	case FLUSH_DELAYED_ITEMS:
4849 		if (state == FLUSH_DELAYED_ITEMS_NR)
4850 			nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
4851 		else
4852 			nr = -1;
4853 
4854 		trans = btrfs_join_transaction(root);
4855 		if (IS_ERR(trans)) {
4856 			ret = PTR_ERR(trans);
4857 			break;
4858 		}
4859 		ret = btrfs_run_delayed_items_nr(trans, fs_info, nr);
4860 		btrfs_end_transaction(trans);
4861 		break;
4862 	case FLUSH_DELALLOC:
4863 	case FLUSH_DELALLOC_WAIT:
4864 		shrink_delalloc(root, num_bytes * 2, orig_bytes,
4865 				state == FLUSH_DELALLOC_WAIT);
4866 		break;
4867 	case ALLOC_CHUNK:
4868 		trans = btrfs_join_transaction(root);
4869 		if (IS_ERR(trans)) {
4870 			ret = PTR_ERR(trans);
4871 			break;
4872 		}
4873 		ret = do_chunk_alloc(trans, fs_info,
4874 				     btrfs_get_alloc_profile(root, 0),
4875 				     CHUNK_ALLOC_NO_FORCE);
4876 		btrfs_end_transaction(trans);
4877 		if (ret > 0 || ret == -ENOSPC)
4878 			ret = 0;
4879 		break;
4880 	case COMMIT_TRANS:
4881 		ret = may_commit_transaction(root, space_info, orig_bytes, 0);
4882 		break;
4883 	default:
4884 		ret = -ENOSPC;
4885 		break;
4886 	}
4887 
4888 	trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes,
4889 				orig_bytes, state, ret);
4890 	return ret;
4891 }
4892 
4893 static inline u64
4894 btrfs_calc_reclaim_metadata_size(struct btrfs_root *root,
4895 				 struct btrfs_space_info *space_info)
4896 {
4897 	struct reserve_ticket *ticket;
4898 	u64 used;
4899 	u64 expected;
4900 	u64 to_reclaim = 0;
4901 
4902 	list_for_each_entry(ticket, &space_info->tickets, list)
4903 		to_reclaim += ticket->bytes;
4904 	list_for_each_entry(ticket, &space_info->priority_tickets, list)
4905 		to_reclaim += ticket->bytes;
4906 	if (to_reclaim)
4907 		return to_reclaim;
4908 
4909 	to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
4910 	if (can_overcommit(root, space_info, to_reclaim,
4911 			   BTRFS_RESERVE_FLUSH_ALL))
4912 		return 0;
4913 
4914 	used = space_info->bytes_used + space_info->bytes_reserved +
4915 	       space_info->bytes_pinned + space_info->bytes_readonly +
4916 	       space_info->bytes_may_use;
4917 	if (can_overcommit(root, space_info, SZ_1M, BTRFS_RESERVE_FLUSH_ALL))
4918 		expected = div_factor_fine(space_info->total_bytes, 95);
4919 	else
4920 		expected = div_factor_fine(space_info->total_bytes, 90);
4921 
4922 	if (used > expected)
4923 		to_reclaim = used - expected;
4924 	else
4925 		to_reclaim = 0;
4926 	to_reclaim = min(to_reclaim, space_info->bytes_may_use +
4927 				     space_info->bytes_reserved);
4928 	return to_reclaim;
4929 }
4930 
4931 static inline int need_do_async_reclaim(struct btrfs_space_info *space_info,
4932 					struct btrfs_root *root, u64 used)
4933 {
4934 	struct btrfs_fs_info *fs_info = root->fs_info;
4935 	u64 thresh = div_factor_fine(space_info->total_bytes, 98);
4936 
4937 	/* If we're just plain full then async reclaim just slows us down. */
4938 	if ((space_info->bytes_used + space_info->bytes_reserved) >= thresh)
4939 		return 0;
4940 
4941 	if (!btrfs_calc_reclaim_metadata_size(root, space_info))
4942 		return 0;
4943 
4944 	return (used >= thresh && !btrfs_fs_closing(fs_info) &&
4945 		!test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
4946 }
4947 
4948 static void wake_all_tickets(struct list_head *head)
4949 {
4950 	struct reserve_ticket *ticket;
4951 
4952 	while (!list_empty(head)) {
4953 		ticket = list_first_entry(head, struct reserve_ticket, list);
4954 		list_del_init(&ticket->list);
4955 		ticket->error = -ENOSPC;
4956 		wake_up(&ticket->wait);
4957 	}
4958 }
4959 
4960 /*
4961  * This is for normal flushers, we can wait all goddamned day if we want to.  We
4962  * will loop and continuously try to flush as long as we are making progress.
4963  * We count progress as clearing off tickets each time we have to loop.
4964  */
4965 static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
4966 {
4967 	struct btrfs_fs_info *fs_info;
4968 	struct btrfs_space_info *space_info;
4969 	u64 to_reclaim;
4970 	int flush_state;
4971 	int commit_cycles = 0;
4972 	u64 last_tickets_id;
4973 
4974 	fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
4975 	space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
4976 
4977 	spin_lock(&space_info->lock);
4978 	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info->fs_root,
4979 						      space_info);
4980 	if (!to_reclaim) {
4981 		space_info->flush = 0;
4982 		spin_unlock(&space_info->lock);
4983 		return;
4984 	}
4985 	last_tickets_id = space_info->tickets_id;
4986 	spin_unlock(&space_info->lock);
4987 
4988 	flush_state = FLUSH_DELAYED_ITEMS_NR;
4989 	do {
4990 		struct reserve_ticket *ticket;
4991 		int ret;
4992 
4993 		ret = flush_space(fs_info->fs_root, space_info, to_reclaim,
4994 			    to_reclaim, flush_state);
4995 		spin_lock(&space_info->lock);
4996 		if (list_empty(&space_info->tickets)) {
4997 			space_info->flush = 0;
4998 			spin_unlock(&space_info->lock);
4999 			return;
5000 		}
5001 		to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info->fs_root,
5002 							      space_info);
5003 		ticket = list_first_entry(&space_info->tickets,
5004 					  struct reserve_ticket, list);
5005 		if (last_tickets_id == space_info->tickets_id) {
5006 			flush_state++;
5007 		} else {
5008 			last_tickets_id = space_info->tickets_id;
5009 			flush_state = FLUSH_DELAYED_ITEMS_NR;
5010 			if (commit_cycles)
5011 				commit_cycles--;
5012 		}
5013 
5014 		if (flush_state > COMMIT_TRANS) {
5015 			commit_cycles++;
5016 			if (commit_cycles > 2) {
5017 				wake_all_tickets(&space_info->tickets);
5018 				space_info->flush = 0;
5019 			} else {
5020 				flush_state = FLUSH_DELAYED_ITEMS_NR;
5021 			}
5022 		}
5023 		spin_unlock(&space_info->lock);
5024 	} while (flush_state <= COMMIT_TRANS);
5025 }
5026 
5027 void btrfs_init_async_reclaim_work(struct work_struct *work)
5028 {
5029 	INIT_WORK(work, btrfs_async_reclaim_metadata_space);
5030 }
5031 
5032 static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
5033 					    struct btrfs_space_info *space_info,
5034 					    struct reserve_ticket *ticket)
5035 {
5036 	u64 to_reclaim;
5037 	int flush_state = FLUSH_DELAYED_ITEMS_NR;
5038 
5039 	spin_lock(&space_info->lock);
5040 	to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info->fs_root,
5041 						      space_info);
5042 	if (!to_reclaim) {
5043 		spin_unlock(&space_info->lock);
5044 		return;
5045 	}
5046 	spin_unlock(&space_info->lock);
5047 
5048 	do {
5049 		flush_space(fs_info->fs_root, space_info, to_reclaim,
5050 			    to_reclaim, flush_state);
5051 		flush_state++;
5052 		spin_lock(&space_info->lock);
5053 		if (ticket->bytes == 0) {
5054 			spin_unlock(&space_info->lock);
5055 			return;
5056 		}
5057 		spin_unlock(&space_info->lock);
5058 
5059 		/*
5060 		 * Priority flushers can't wait on delalloc without
5061 		 * deadlocking.
5062 		 */
5063 		if (flush_state == FLUSH_DELALLOC ||
5064 		    flush_state == FLUSH_DELALLOC_WAIT)
5065 			flush_state = ALLOC_CHUNK;
5066 	} while (flush_state < COMMIT_TRANS);
5067 }
5068 
5069 static int wait_reserve_ticket(struct btrfs_fs_info *fs_info,
5070 			       struct btrfs_space_info *space_info,
5071 			       struct reserve_ticket *ticket, u64 orig_bytes)
5072 
5073 {
5074 	DEFINE_WAIT(wait);
5075 	int ret = 0;
5076 
5077 	spin_lock(&space_info->lock);
5078 	while (ticket->bytes > 0 && ticket->error == 0) {
5079 		ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
5080 		if (ret) {
5081 			ret = -EINTR;
5082 			break;
5083 		}
5084 		spin_unlock(&space_info->lock);
5085 
5086 		schedule();
5087 
5088 		finish_wait(&ticket->wait, &wait);
5089 		spin_lock(&space_info->lock);
5090 	}
5091 	if (!ret)
5092 		ret = ticket->error;
5093 	if (!list_empty(&ticket->list))
5094 		list_del_init(&ticket->list);
5095 	if (ticket->bytes && ticket->bytes < orig_bytes) {
5096 		u64 num_bytes = orig_bytes - ticket->bytes;
5097 		space_info->bytes_may_use -= num_bytes;
5098 		trace_btrfs_space_reservation(fs_info, "space_info",
5099 					      space_info->flags, num_bytes, 0);
5100 	}
5101 	spin_unlock(&space_info->lock);
5102 
5103 	return ret;
5104 }
5105 
5106 /**
5107  * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
5108  * @root - the root we're allocating for
5109  * @space_info - the space info we want to allocate from
5110  * @orig_bytes - the number of bytes we want
5111  * @flush - whether or not we can flush to make our reservation
5112  *
5113  * This will reserve orig_bytes number of bytes from the space info associated
5114  * with the block_rsv.  If there is not enough space it will make an attempt to
5115  * flush out space to make room.  It will do this by flushing delalloc if
5116  * possible or committing the transaction.  If flush is 0 then no attempts to
5117  * regain reservations will be made and this will fail if there is not enough
5118  * space already.
5119  */
5120 static int __reserve_metadata_bytes(struct btrfs_root *root,
5121 				    struct btrfs_space_info *space_info,
5122 				    u64 orig_bytes,
5123 				    enum btrfs_reserve_flush_enum flush)
5124 {
5125 	struct btrfs_fs_info *fs_info = root->fs_info;
5126 	struct reserve_ticket ticket;
5127 	u64 used;
5128 	int ret = 0;
5129 
5130 	ASSERT(orig_bytes);
5131 	ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
5132 
5133 	spin_lock(&space_info->lock);
5134 	ret = -ENOSPC;
5135 	used = space_info->bytes_used + space_info->bytes_reserved +
5136 		space_info->bytes_pinned + space_info->bytes_readonly +
5137 		space_info->bytes_may_use;
5138 
5139 	/*
5140 	 * If we have enough space then hooray, make our reservation and carry
5141 	 * on.  If not see if we can overcommit, and if we can, hooray carry on.
5142 	 * If not things get more complicated.
5143 	 */
5144 	if (used + orig_bytes <= space_info->total_bytes) {
5145 		space_info->bytes_may_use += orig_bytes;
5146 		trace_btrfs_space_reservation(fs_info, "space_info",
5147 					      space_info->flags, orig_bytes, 1);
5148 		ret = 0;
5149 	} else if (can_overcommit(root, space_info, orig_bytes, flush)) {
5150 		space_info->bytes_may_use += orig_bytes;
5151 		trace_btrfs_space_reservation(fs_info, "space_info",
5152 					      space_info->flags, orig_bytes, 1);
5153 		ret = 0;
5154 	}
5155 
5156 	/*
5157 	 * If we couldn't make a reservation then setup our reservation ticket
5158 	 * and kick the async worker if it's not already running.
5159 	 *
5160 	 * If we are a priority flusher then we just need to add our ticket to
5161 	 * the list and we will do our own flushing further down.
5162 	 */
5163 	if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
5164 		ticket.bytes = orig_bytes;
5165 		ticket.error = 0;
5166 		init_waitqueue_head(&ticket.wait);
5167 		if (flush == BTRFS_RESERVE_FLUSH_ALL) {
5168 			list_add_tail(&ticket.list, &space_info->tickets);
5169 			if (!space_info->flush) {
5170 				space_info->flush = 1;
5171 				trace_btrfs_trigger_flush(fs_info,
5172 							  space_info->flags,
5173 							  orig_bytes, flush,
5174 							  "enospc");
5175 				queue_work(system_unbound_wq,
5176 					   &root->fs_info->async_reclaim_work);
5177 			}
5178 		} else {
5179 			list_add_tail(&ticket.list,
5180 				      &space_info->priority_tickets);
5181 		}
5182 	} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
5183 		used += orig_bytes;
5184 		/*
5185 		 * We will do the space reservation dance during log replay,
5186 		 * which means we won't have fs_info->fs_root set, so don't do
5187 		 * the async reclaim as we will panic.
5188 		 */
5189 		if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
5190 		    need_do_async_reclaim(space_info, root, used) &&
5191 		    !work_busy(&fs_info->async_reclaim_work)) {
5192 			trace_btrfs_trigger_flush(fs_info, space_info->flags,
5193 						  orig_bytes, flush, "preempt");
5194 			queue_work(system_unbound_wq,
5195 				   &fs_info->async_reclaim_work);
5196 		}
5197 	}
5198 	spin_unlock(&space_info->lock);
5199 	if (!ret || flush == BTRFS_RESERVE_NO_FLUSH)
5200 		return ret;
5201 
5202 	if (flush == BTRFS_RESERVE_FLUSH_ALL)
5203 		return wait_reserve_ticket(fs_info, space_info, &ticket,
5204 					   orig_bytes);
5205 
5206 	ret = 0;
5207 	priority_reclaim_metadata_space(fs_info, space_info, &ticket);
5208 	spin_lock(&space_info->lock);
5209 	if (ticket.bytes) {
5210 		if (ticket.bytes < orig_bytes) {
5211 			u64 num_bytes = orig_bytes - ticket.bytes;
5212 			space_info->bytes_may_use -= num_bytes;
5213 			trace_btrfs_space_reservation(fs_info, "space_info",
5214 						      space_info->flags,
5215 						      num_bytes, 0);
5216 
5217 		}
5218 		list_del_init(&ticket.list);
5219 		ret = -ENOSPC;
5220 	}
5221 	spin_unlock(&space_info->lock);
5222 	ASSERT(list_empty(&ticket.list));
5223 	return ret;
5224 }
5225 
5226 /**
5227  * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
5228  * @root - the root we're allocating for
5229  * @block_rsv - the block_rsv we're allocating for
5230  * @orig_bytes - the number of bytes we want
5231  * @flush - whether or not we can flush to make our reservation
5232  *
5233  * This will reserve orgi_bytes number of bytes from the space info associated
5234  * with the block_rsv.  If there is not enough space it will make an attempt to
5235  * flush out space to make room.  It will do this by flushing delalloc if
5236  * possible or committing the transaction.  If flush is 0 then no attempts to
5237  * regain reservations will be made and this will fail if there is not enough
5238  * space already.
5239  */
5240 static int reserve_metadata_bytes(struct btrfs_root *root,
5241 				  struct btrfs_block_rsv *block_rsv,
5242 				  u64 orig_bytes,
5243 				  enum btrfs_reserve_flush_enum flush)
5244 {
5245 	struct btrfs_fs_info *fs_info = root->fs_info;
5246 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
5247 	int ret;
5248 
5249 	ret = __reserve_metadata_bytes(root, block_rsv->space_info, orig_bytes,
5250 				       flush);
5251 	if (ret == -ENOSPC &&
5252 	    unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
5253 		if (block_rsv != global_rsv &&
5254 		    !block_rsv_use_bytes(global_rsv, orig_bytes))
5255 			ret = 0;
5256 	}
5257 	if (ret == -ENOSPC)
5258 		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
5259 					      block_rsv->space_info->flags,
5260 					      orig_bytes, 1);
5261 	return ret;
5262 }
5263 
5264 static struct btrfs_block_rsv *get_block_rsv(
5265 					const struct btrfs_trans_handle *trans,
5266 					const struct btrfs_root *root)
5267 {
5268 	struct btrfs_fs_info *fs_info = root->fs_info;
5269 	struct btrfs_block_rsv *block_rsv = NULL;
5270 
5271 	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
5272 	    (root == fs_info->csum_root && trans->adding_csums) ||
5273 	    (root == fs_info->uuid_root))
5274 		block_rsv = trans->block_rsv;
5275 
5276 	if (!block_rsv)
5277 		block_rsv = root->block_rsv;
5278 
5279 	if (!block_rsv)
5280 		block_rsv = &fs_info->empty_block_rsv;
5281 
5282 	return block_rsv;
5283 }
5284 
5285 static int block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv,
5286 			       u64 num_bytes)
5287 {
5288 	int ret = -ENOSPC;
5289 	spin_lock(&block_rsv->lock);
5290 	if (block_rsv->reserved >= num_bytes) {
5291 		block_rsv->reserved -= num_bytes;
5292 		if (block_rsv->reserved < block_rsv->size)
5293 			block_rsv->full = 0;
5294 		ret = 0;
5295 	}
5296 	spin_unlock(&block_rsv->lock);
5297 	return ret;
5298 }
5299 
5300 static void block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
5301 				u64 num_bytes, int update_size)
5302 {
5303 	spin_lock(&block_rsv->lock);
5304 	block_rsv->reserved += num_bytes;
5305 	if (update_size)
5306 		block_rsv->size += num_bytes;
5307 	else if (block_rsv->reserved >= block_rsv->size)
5308 		block_rsv->full = 1;
5309 	spin_unlock(&block_rsv->lock);
5310 }
5311 
5312 int btrfs_cond_migrate_bytes(struct btrfs_fs_info *fs_info,
5313 			     struct btrfs_block_rsv *dest, u64 num_bytes,
5314 			     int min_factor)
5315 {
5316 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
5317 	u64 min_bytes;
5318 
5319 	if (global_rsv->space_info != dest->space_info)
5320 		return -ENOSPC;
5321 
5322 	spin_lock(&global_rsv->lock);
5323 	min_bytes = div_factor(global_rsv->size, min_factor);
5324 	if (global_rsv->reserved < min_bytes + num_bytes) {
5325 		spin_unlock(&global_rsv->lock);
5326 		return -ENOSPC;
5327 	}
5328 	global_rsv->reserved -= num_bytes;
5329 	if (global_rsv->reserved < global_rsv->size)
5330 		global_rsv->full = 0;
5331 	spin_unlock(&global_rsv->lock);
5332 
5333 	block_rsv_add_bytes(dest, num_bytes, 1);
5334 	return 0;
5335 }
5336 
5337 /*
5338  * This is for space we already have accounted in space_info->bytes_may_use, so
5339  * basically when we're returning space from block_rsv's.
5340  */
5341 static void space_info_add_old_bytes(struct btrfs_fs_info *fs_info,
5342 				     struct btrfs_space_info *space_info,
5343 				     u64 num_bytes)
5344 {
5345 	struct reserve_ticket *ticket;
5346 	struct list_head *head;
5347 	u64 used;
5348 	enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
5349 	bool check_overcommit = false;
5350 
5351 	spin_lock(&space_info->lock);
5352 	head = &space_info->priority_tickets;
5353 
5354 	/*
5355 	 * If we are over our limit then we need to check and see if we can
5356 	 * overcommit, and if we can't then we just need to free up our space
5357 	 * and not satisfy any requests.
5358 	 */
5359 	used = space_info->bytes_used + space_info->bytes_reserved +
5360 		space_info->bytes_pinned + space_info->bytes_readonly +
5361 		space_info->bytes_may_use;
5362 	if (used - num_bytes >= space_info->total_bytes)
5363 		check_overcommit = true;
5364 again:
5365 	while (!list_empty(head) && num_bytes) {
5366 		ticket = list_first_entry(head, struct reserve_ticket,
5367 					  list);
5368 		/*
5369 		 * We use 0 bytes because this space is already reserved, so
5370 		 * adding the ticket space would be a double count.
5371 		 */
5372 		if (check_overcommit &&
5373 		    !can_overcommit(fs_info->extent_root, space_info, 0,
5374 				    flush))
5375 			break;
5376 		if (num_bytes >= ticket->bytes) {
5377 			list_del_init(&ticket->list);
5378 			num_bytes -= ticket->bytes;
5379 			ticket->bytes = 0;
5380 			space_info->tickets_id++;
5381 			wake_up(&ticket->wait);
5382 		} else {
5383 			ticket->bytes -= num_bytes;
5384 			num_bytes = 0;
5385 		}
5386 	}
5387 
5388 	if (num_bytes && head == &space_info->priority_tickets) {
5389 		head = &space_info->tickets;
5390 		flush = BTRFS_RESERVE_FLUSH_ALL;
5391 		goto again;
5392 	}
5393 	space_info->bytes_may_use -= num_bytes;
5394 	trace_btrfs_space_reservation(fs_info, "space_info",
5395 				      space_info->flags, num_bytes, 0);
5396 	spin_unlock(&space_info->lock);
5397 }
5398 
5399 /*
5400  * This is for newly allocated space that isn't accounted in
5401  * space_info->bytes_may_use yet.  So if we allocate a chunk or unpin an extent
5402  * we use this helper.
5403  */
5404 static void space_info_add_new_bytes(struct btrfs_fs_info *fs_info,
5405 				     struct btrfs_space_info *space_info,
5406 				     u64 num_bytes)
5407 {
5408 	struct reserve_ticket *ticket;
5409 	struct list_head *head = &space_info->priority_tickets;
5410 
5411 again:
5412 	while (!list_empty(head) && num_bytes) {
5413 		ticket = list_first_entry(head, struct reserve_ticket,
5414 					  list);
5415 		if (num_bytes >= ticket->bytes) {
5416 			trace_btrfs_space_reservation(fs_info, "space_info",
5417 						      space_info->flags,
5418 						      ticket->bytes, 1);
5419 			list_del_init(&ticket->list);
5420 			num_bytes -= ticket->bytes;
5421 			space_info->bytes_may_use += ticket->bytes;
5422 			ticket->bytes = 0;
5423 			space_info->tickets_id++;
5424 			wake_up(&ticket->wait);
5425 		} else {
5426 			trace_btrfs_space_reservation(fs_info, "space_info",
5427 						      space_info->flags,
5428 						      num_bytes, 1);
5429 			space_info->bytes_may_use += num_bytes;
5430 			ticket->bytes -= num_bytes;
5431 			num_bytes = 0;
5432 		}
5433 	}
5434 
5435 	if (num_bytes && head == &space_info->priority_tickets) {
5436 		head = &space_info->tickets;
5437 		goto again;
5438 	}
5439 }
5440 
5441 static void block_rsv_release_bytes(struct btrfs_fs_info *fs_info,
5442 				    struct btrfs_block_rsv *block_rsv,
5443 				    struct btrfs_block_rsv *dest, u64 num_bytes)
5444 {
5445 	struct btrfs_space_info *space_info = block_rsv->space_info;
5446 
5447 	spin_lock(&block_rsv->lock);
5448 	if (num_bytes == (u64)-1)
5449 		num_bytes = block_rsv->size;
5450 	block_rsv->size -= num_bytes;
5451 	if (block_rsv->reserved >= block_rsv->size) {
5452 		num_bytes = block_rsv->reserved - block_rsv->size;
5453 		block_rsv->reserved = block_rsv->size;
5454 		block_rsv->full = 1;
5455 	} else {
5456 		num_bytes = 0;
5457 	}
5458 	spin_unlock(&block_rsv->lock);
5459 
5460 	if (num_bytes > 0) {
5461 		if (dest) {
5462 			spin_lock(&dest->lock);
5463 			if (!dest->full) {
5464 				u64 bytes_to_add;
5465 
5466 				bytes_to_add = dest->size - dest->reserved;
5467 				bytes_to_add = min(num_bytes, bytes_to_add);
5468 				dest->reserved += bytes_to_add;
5469 				if (dest->reserved >= dest->size)
5470 					dest->full = 1;
5471 				num_bytes -= bytes_to_add;
5472 			}
5473 			spin_unlock(&dest->lock);
5474 		}
5475 		if (num_bytes)
5476 			space_info_add_old_bytes(fs_info, space_info,
5477 						 num_bytes);
5478 	}
5479 }
5480 
5481 int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src,
5482 			    struct btrfs_block_rsv *dst, u64 num_bytes,
5483 			    int update_size)
5484 {
5485 	int ret;
5486 
5487 	ret = block_rsv_use_bytes(src, num_bytes);
5488 	if (ret)
5489 		return ret;
5490 
5491 	block_rsv_add_bytes(dst, num_bytes, update_size);
5492 	return 0;
5493 }
5494 
5495 void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, unsigned short type)
5496 {
5497 	memset(rsv, 0, sizeof(*rsv));
5498 	spin_lock_init(&rsv->lock);
5499 	rsv->type = type;
5500 }
5501 
5502 struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
5503 					      unsigned short type)
5504 {
5505 	struct btrfs_block_rsv *block_rsv;
5506 
5507 	block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
5508 	if (!block_rsv)
5509 		return NULL;
5510 
5511 	btrfs_init_block_rsv(block_rsv, type);
5512 	block_rsv->space_info = __find_space_info(fs_info,
5513 						  BTRFS_BLOCK_GROUP_METADATA);
5514 	return block_rsv;
5515 }
5516 
5517 void btrfs_free_block_rsv(struct btrfs_fs_info *fs_info,
5518 			  struct btrfs_block_rsv *rsv)
5519 {
5520 	if (!rsv)
5521 		return;
5522 	btrfs_block_rsv_release(fs_info, rsv, (u64)-1);
5523 	kfree(rsv);
5524 }
5525 
5526 void __btrfs_free_block_rsv(struct btrfs_block_rsv *rsv)
5527 {
5528 	kfree(rsv);
5529 }
5530 
5531 int btrfs_block_rsv_add(struct btrfs_root *root,
5532 			struct btrfs_block_rsv *block_rsv, u64 num_bytes,
5533 			enum btrfs_reserve_flush_enum flush)
5534 {
5535 	int ret;
5536 
5537 	if (num_bytes == 0)
5538 		return 0;
5539 
5540 	ret = reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
5541 	if (!ret) {
5542 		block_rsv_add_bytes(block_rsv, num_bytes, 1);
5543 		return 0;
5544 	}
5545 
5546 	return ret;
5547 }
5548 
5549 int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
5550 {
5551 	u64 num_bytes = 0;
5552 	int ret = -ENOSPC;
5553 
5554 	if (!block_rsv)
5555 		return 0;
5556 
5557 	spin_lock(&block_rsv->lock);
5558 	num_bytes = div_factor(block_rsv->size, min_factor);
5559 	if (block_rsv->reserved >= num_bytes)
5560 		ret = 0;
5561 	spin_unlock(&block_rsv->lock);
5562 
5563 	return ret;
5564 }
5565 
5566 int btrfs_block_rsv_refill(struct btrfs_root *root,
5567 			   struct btrfs_block_rsv *block_rsv, u64 min_reserved,
5568 			   enum btrfs_reserve_flush_enum flush)
5569 {
5570 	u64 num_bytes = 0;
5571 	int ret = -ENOSPC;
5572 
5573 	if (!block_rsv)
5574 		return 0;
5575 
5576 	spin_lock(&block_rsv->lock);
5577 	num_bytes = min_reserved;
5578 	if (block_rsv->reserved >= num_bytes)
5579 		ret = 0;
5580 	else
5581 		num_bytes -= block_rsv->reserved;
5582 	spin_unlock(&block_rsv->lock);
5583 
5584 	if (!ret)
5585 		return 0;
5586 
5587 	ret = reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
5588 	if (!ret) {
5589 		block_rsv_add_bytes(block_rsv, num_bytes, 0);
5590 		return 0;
5591 	}
5592 
5593 	return ret;
5594 }
5595 
5596 void btrfs_block_rsv_release(struct btrfs_fs_info *fs_info,
5597 			     struct btrfs_block_rsv *block_rsv,
5598 			     u64 num_bytes)
5599 {
5600 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
5601 
5602 	if (global_rsv == block_rsv ||
5603 	    block_rsv->space_info != global_rsv->space_info)
5604 		global_rsv = NULL;
5605 	block_rsv_release_bytes(fs_info, block_rsv, global_rsv, num_bytes);
5606 }
5607 
5608 static void update_global_block_rsv(struct btrfs_fs_info *fs_info)
5609 {
5610 	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
5611 	struct btrfs_space_info *sinfo = block_rsv->space_info;
5612 	u64 num_bytes;
5613 
5614 	/*
5615 	 * The global block rsv is based on the size of the extent tree, the
5616 	 * checksum tree and the root tree.  If the fs is empty we want to set
5617 	 * it to a minimal amount for safety.
5618 	 */
5619 	num_bytes = btrfs_root_used(&fs_info->extent_root->root_item) +
5620 		btrfs_root_used(&fs_info->csum_root->root_item) +
5621 		btrfs_root_used(&fs_info->tree_root->root_item);
5622 	num_bytes = max_t(u64, num_bytes, SZ_16M);
5623 
5624 	spin_lock(&sinfo->lock);
5625 	spin_lock(&block_rsv->lock);
5626 
5627 	block_rsv->size = min_t(u64, num_bytes, SZ_512M);
5628 
5629 	if (block_rsv->reserved < block_rsv->size) {
5630 		num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
5631 			sinfo->bytes_reserved + sinfo->bytes_readonly +
5632 			sinfo->bytes_may_use;
5633 		if (sinfo->total_bytes > num_bytes) {
5634 			num_bytes = sinfo->total_bytes - num_bytes;
5635 			num_bytes = min(num_bytes,
5636 					block_rsv->size - block_rsv->reserved);
5637 			block_rsv->reserved += num_bytes;
5638 			sinfo->bytes_may_use += num_bytes;
5639 			trace_btrfs_space_reservation(fs_info, "space_info",
5640 						      sinfo->flags, num_bytes,
5641 						      1);
5642 		}
5643 	} else if (block_rsv->reserved > block_rsv->size) {
5644 		num_bytes = block_rsv->reserved - block_rsv->size;
5645 		sinfo->bytes_may_use -= num_bytes;
5646 		trace_btrfs_space_reservation(fs_info, "space_info",
5647 				      sinfo->flags, num_bytes, 0);
5648 		block_rsv->reserved = block_rsv->size;
5649 	}
5650 
5651 	if (block_rsv->reserved == block_rsv->size)
5652 		block_rsv->full = 1;
5653 	else
5654 		block_rsv->full = 0;
5655 
5656 	spin_unlock(&block_rsv->lock);
5657 	spin_unlock(&sinfo->lock);
5658 }
5659 
5660 static void init_global_block_rsv(struct btrfs_fs_info *fs_info)
5661 {
5662 	struct btrfs_space_info *space_info;
5663 
5664 	space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
5665 	fs_info->chunk_block_rsv.space_info = space_info;
5666 
5667 	space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
5668 	fs_info->global_block_rsv.space_info = space_info;
5669 	fs_info->delalloc_block_rsv.space_info = space_info;
5670 	fs_info->trans_block_rsv.space_info = space_info;
5671 	fs_info->empty_block_rsv.space_info = space_info;
5672 	fs_info->delayed_block_rsv.space_info = space_info;
5673 
5674 	fs_info->extent_root->block_rsv = &fs_info->global_block_rsv;
5675 	fs_info->csum_root->block_rsv = &fs_info->global_block_rsv;
5676 	fs_info->dev_root->block_rsv = &fs_info->global_block_rsv;
5677 	fs_info->tree_root->block_rsv = &fs_info->global_block_rsv;
5678 	if (fs_info->quota_root)
5679 		fs_info->quota_root->block_rsv = &fs_info->global_block_rsv;
5680 	fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
5681 
5682 	update_global_block_rsv(fs_info);
5683 }
5684 
5685 static void release_global_block_rsv(struct btrfs_fs_info *fs_info)
5686 {
5687 	block_rsv_release_bytes(fs_info, &fs_info->global_block_rsv, NULL,
5688 				(u64)-1);
5689 	WARN_ON(fs_info->delalloc_block_rsv.size > 0);
5690 	WARN_ON(fs_info->delalloc_block_rsv.reserved > 0);
5691 	WARN_ON(fs_info->trans_block_rsv.size > 0);
5692 	WARN_ON(fs_info->trans_block_rsv.reserved > 0);
5693 	WARN_ON(fs_info->chunk_block_rsv.size > 0);
5694 	WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
5695 	WARN_ON(fs_info->delayed_block_rsv.size > 0);
5696 	WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
5697 }
5698 
5699 void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
5700 				  struct btrfs_fs_info *fs_info)
5701 {
5702 	if (!trans->block_rsv)
5703 		return;
5704 
5705 	if (!trans->bytes_reserved)
5706 		return;
5707 
5708 	trace_btrfs_space_reservation(fs_info, "transaction",
5709 				      trans->transid, trans->bytes_reserved, 0);
5710 	btrfs_block_rsv_release(fs_info, trans->block_rsv,
5711 				trans->bytes_reserved);
5712 	trans->bytes_reserved = 0;
5713 }
5714 
5715 /*
5716  * To be called after all the new block groups attached to the transaction
5717  * handle have been created (btrfs_create_pending_block_groups()).
5718  */
5719 void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)
5720 {
5721 	struct btrfs_fs_info *fs_info = trans->fs_info;
5722 
5723 	if (!trans->chunk_bytes_reserved)
5724 		return;
5725 
5726 	WARN_ON_ONCE(!list_empty(&trans->new_bgs));
5727 
5728 	block_rsv_release_bytes(fs_info, &fs_info->chunk_block_rsv, NULL,
5729 				trans->chunk_bytes_reserved);
5730 	trans->chunk_bytes_reserved = 0;
5731 }
5732 
5733 /* Can only return 0 or -ENOSPC */
5734 int btrfs_orphan_reserve_metadata(struct btrfs_trans_handle *trans,
5735 				  struct inode *inode)
5736 {
5737 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5738 	struct btrfs_root *root = BTRFS_I(inode)->root;
5739 	/*
5740 	 * We always use trans->block_rsv here as we will have reserved space
5741 	 * for our orphan when starting the transaction, using get_block_rsv()
5742 	 * here will sometimes make us choose the wrong block rsv as we could be
5743 	 * doing a reloc inode for a non refcounted root.
5744 	 */
5745 	struct btrfs_block_rsv *src_rsv = trans->block_rsv;
5746 	struct btrfs_block_rsv *dst_rsv = root->orphan_block_rsv;
5747 
5748 	/*
5749 	 * We need to hold space in order to delete our orphan item once we've
5750 	 * added it, so this takes the reservation so we can release it later
5751 	 * when we are truly done with the orphan item.
5752 	 */
5753 	u64 num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
5754 
5755 	trace_btrfs_space_reservation(fs_info, "orphan",
5756 				      btrfs_ino(inode), num_bytes, 1);
5757 	return btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, 1);
5758 }
5759 
5760 void btrfs_orphan_release_metadata(struct inode *inode)
5761 {
5762 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5763 	struct btrfs_root *root = BTRFS_I(inode)->root;
5764 	u64 num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
5765 
5766 	trace_btrfs_space_reservation(fs_info, "orphan",
5767 				      btrfs_ino(inode), num_bytes, 0);
5768 	btrfs_block_rsv_release(fs_info, root->orphan_block_rsv, num_bytes);
5769 }
5770 
5771 /*
5772  * btrfs_subvolume_reserve_metadata() - reserve space for subvolume operation
5773  * root: the root of the parent directory
5774  * rsv: block reservation
5775  * items: the number of items that we need do reservation
5776  * qgroup_reserved: used to return the reserved size in qgroup
5777  *
5778  * This function is used to reserve the space for snapshot/subvolume
5779  * creation and deletion. Those operations are different with the
5780  * common file/directory operations, they change two fs/file trees
5781  * and root tree, the number of items that the qgroup reserves is
5782  * different with the free space reservation. So we can not use
5783  * the space reservation mechanism in start_transaction().
5784  */
5785 int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
5786 				     struct btrfs_block_rsv *rsv,
5787 				     int items,
5788 				     u64 *qgroup_reserved,
5789 				     bool use_global_rsv)
5790 {
5791 	u64 num_bytes;
5792 	int ret;
5793 	struct btrfs_fs_info *fs_info = root->fs_info;
5794 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
5795 
5796 	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
5797 		/* One for parent inode, two for dir entries */
5798 		num_bytes = 3 * fs_info->nodesize;
5799 		ret = btrfs_qgroup_reserve_meta(root, num_bytes);
5800 		if (ret)
5801 			return ret;
5802 	} else {
5803 		num_bytes = 0;
5804 	}
5805 
5806 	*qgroup_reserved = num_bytes;
5807 
5808 	num_bytes = btrfs_calc_trans_metadata_size(fs_info, items);
5809 	rsv->space_info = __find_space_info(fs_info,
5810 					    BTRFS_BLOCK_GROUP_METADATA);
5811 	ret = btrfs_block_rsv_add(root, rsv, num_bytes,
5812 				  BTRFS_RESERVE_FLUSH_ALL);
5813 
5814 	if (ret == -ENOSPC && use_global_rsv)
5815 		ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, 1);
5816 
5817 	if (ret && *qgroup_reserved)
5818 		btrfs_qgroup_free_meta(root, *qgroup_reserved);
5819 
5820 	return ret;
5821 }
5822 
5823 void btrfs_subvolume_release_metadata(struct btrfs_fs_info *fs_info,
5824 				      struct btrfs_block_rsv *rsv,
5825 				      u64 qgroup_reserved)
5826 {
5827 	btrfs_block_rsv_release(fs_info, rsv, (u64)-1);
5828 }
5829 
5830 /**
5831  * drop_outstanding_extent - drop an outstanding extent
5832  * @inode: the inode we're dropping the extent for
5833  * @num_bytes: the number of bytes we're releasing.
5834  *
5835  * This is called when we are freeing up an outstanding extent, either called
5836  * after an error or after an extent is written.  This will return the number of
5837  * reserved extents that need to be freed.  This must be called with
5838  * BTRFS_I(inode)->lock held.
5839  */
5840 static unsigned drop_outstanding_extent(struct inode *inode, u64 num_bytes)
5841 {
5842 	unsigned drop_inode_space = 0;
5843 	unsigned dropped_extents = 0;
5844 	unsigned num_extents = 0;
5845 
5846 	num_extents = (unsigned)div64_u64(num_bytes +
5847 					  BTRFS_MAX_EXTENT_SIZE - 1,
5848 					  BTRFS_MAX_EXTENT_SIZE);
5849 	ASSERT(num_extents);
5850 	ASSERT(BTRFS_I(inode)->outstanding_extents >= num_extents);
5851 	BTRFS_I(inode)->outstanding_extents -= num_extents;
5852 
5853 	if (BTRFS_I(inode)->outstanding_extents == 0 &&
5854 	    test_and_clear_bit(BTRFS_INODE_DELALLOC_META_RESERVED,
5855 			       &BTRFS_I(inode)->runtime_flags))
5856 		drop_inode_space = 1;
5857 
5858 	/*
5859 	 * If we have more or the same amount of outstanding extents than we have
5860 	 * reserved then we need to leave the reserved extents count alone.
5861 	 */
5862 	if (BTRFS_I(inode)->outstanding_extents >=
5863 	    BTRFS_I(inode)->reserved_extents)
5864 		return drop_inode_space;
5865 
5866 	dropped_extents = BTRFS_I(inode)->reserved_extents -
5867 		BTRFS_I(inode)->outstanding_extents;
5868 	BTRFS_I(inode)->reserved_extents -= dropped_extents;
5869 	return dropped_extents + drop_inode_space;
5870 }
5871 
5872 /**
5873  * calc_csum_metadata_size - return the amount of metadata space that must be
5874  *	reserved/freed for the given bytes.
5875  * @inode: the inode we're manipulating
5876  * @num_bytes: the number of bytes in question
5877  * @reserve: 1 if we are reserving space, 0 if we are freeing space
5878  *
5879  * This adjusts the number of csum_bytes in the inode and then returns the
5880  * correct amount of metadata that must either be reserved or freed.  We
5881  * calculate how many checksums we can fit into one leaf and then divide the
5882  * number of bytes that will need to be checksumed by this value to figure out
5883  * how many checksums will be required.  If we are adding bytes then the number
5884  * may go up and we will return the number of additional bytes that must be
5885  * reserved.  If it is going down we will return the number of bytes that must
5886  * be freed.
5887  *
5888  * This must be called with BTRFS_I(inode)->lock held.
5889  */
5890 static u64 calc_csum_metadata_size(struct inode *inode, u64 num_bytes,
5891 				   int reserve)
5892 {
5893 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5894 	u64 old_csums, num_csums;
5895 
5896 	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM &&
5897 	    BTRFS_I(inode)->csum_bytes == 0)
5898 		return 0;
5899 
5900 	old_csums = btrfs_csum_bytes_to_leaves(fs_info,
5901 					       BTRFS_I(inode)->csum_bytes);
5902 	if (reserve)
5903 		BTRFS_I(inode)->csum_bytes += num_bytes;
5904 	else
5905 		BTRFS_I(inode)->csum_bytes -= num_bytes;
5906 	num_csums = btrfs_csum_bytes_to_leaves(fs_info,
5907 					       BTRFS_I(inode)->csum_bytes);
5908 
5909 	/* No change, no need to reserve more */
5910 	if (old_csums == num_csums)
5911 		return 0;
5912 
5913 	if (reserve)
5914 		return btrfs_calc_trans_metadata_size(fs_info,
5915 						      num_csums - old_csums);
5916 
5917 	return btrfs_calc_trans_metadata_size(fs_info, old_csums - num_csums);
5918 }
5919 
5920 int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
5921 {
5922 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
5923 	struct btrfs_root *root = BTRFS_I(inode)->root;
5924 	struct btrfs_block_rsv *block_rsv = &fs_info->delalloc_block_rsv;
5925 	u64 to_reserve = 0;
5926 	u64 csum_bytes;
5927 	unsigned nr_extents = 0;
5928 	enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_ALL;
5929 	int ret = 0;
5930 	bool delalloc_lock = true;
5931 	u64 to_free = 0;
5932 	unsigned dropped;
5933 	bool release_extra = false;
5934 
5935 	/* If we are a free space inode we need to not flush since we will be in
5936 	 * the middle of a transaction commit.  We also don't need the delalloc
5937 	 * mutex since we won't race with anybody.  We need this mostly to make
5938 	 * lockdep shut its filthy mouth.
5939 	 *
5940 	 * If we have a transaction open (can happen if we call truncate_block
5941 	 * from truncate), then we need FLUSH_LIMIT so we don't deadlock.
5942 	 */
5943 	if (btrfs_is_free_space_inode(inode)) {
5944 		flush = BTRFS_RESERVE_NO_FLUSH;
5945 		delalloc_lock = false;
5946 	} else if (current->journal_info) {
5947 		flush = BTRFS_RESERVE_FLUSH_LIMIT;
5948 	}
5949 
5950 	if (flush != BTRFS_RESERVE_NO_FLUSH &&
5951 	    btrfs_transaction_in_commit(fs_info))
5952 		schedule_timeout(1);
5953 
5954 	if (delalloc_lock)
5955 		mutex_lock(&BTRFS_I(inode)->delalloc_mutex);
5956 
5957 	num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
5958 
5959 	spin_lock(&BTRFS_I(inode)->lock);
5960 	nr_extents = (unsigned)div64_u64(num_bytes +
5961 					 BTRFS_MAX_EXTENT_SIZE - 1,
5962 					 BTRFS_MAX_EXTENT_SIZE);
5963 	BTRFS_I(inode)->outstanding_extents += nr_extents;
5964 
5965 	nr_extents = 0;
5966 	if (BTRFS_I(inode)->outstanding_extents >
5967 	    BTRFS_I(inode)->reserved_extents)
5968 		nr_extents += BTRFS_I(inode)->outstanding_extents -
5969 			BTRFS_I(inode)->reserved_extents;
5970 
5971 	/* We always want to reserve a slot for updating the inode. */
5972 	to_reserve = btrfs_calc_trans_metadata_size(fs_info, nr_extents + 1);
5973 	to_reserve += calc_csum_metadata_size(inode, num_bytes, 1);
5974 	csum_bytes = BTRFS_I(inode)->csum_bytes;
5975 	spin_unlock(&BTRFS_I(inode)->lock);
5976 
5977 	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
5978 		ret = btrfs_qgroup_reserve_meta(root,
5979 				nr_extents * fs_info->nodesize);
5980 		if (ret)
5981 			goto out_fail;
5982 	}
5983 
5984 	ret = btrfs_block_rsv_add(root, block_rsv, to_reserve, flush);
5985 	if (unlikely(ret)) {
5986 		btrfs_qgroup_free_meta(root,
5987 				       nr_extents * fs_info->nodesize);
5988 		goto out_fail;
5989 	}
5990 
5991 	spin_lock(&BTRFS_I(inode)->lock);
5992 	if (test_and_set_bit(BTRFS_INODE_DELALLOC_META_RESERVED,
5993 			     &BTRFS_I(inode)->runtime_flags)) {
5994 		to_reserve -= btrfs_calc_trans_metadata_size(fs_info, 1);
5995 		release_extra = true;
5996 	}
5997 	BTRFS_I(inode)->reserved_extents += nr_extents;
5998 	spin_unlock(&BTRFS_I(inode)->lock);
5999 
6000 	if (delalloc_lock)
6001 		mutex_unlock(&BTRFS_I(inode)->delalloc_mutex);
6002 
6003 	if (to_reserve)
6004 		trace_btrfs_space_reservation(fs_info, "delalloc",
6005 					      btrfs_ino(inode), to_reserve, 1);
6006 	if (release_extra)
6007 		btrfs_block_rsv_release(fs_info, block_rsv,
6008 				btrfs_calc_trans_metadata_size(fs_info, 1));
6009 	return 0;
6010 
6011 out_fail:
6012 	spin_lock(&BTRFS_I(inode)->lock);
6013 	dropped = drop_outstanding_extent(inode, num_bytes);
6014 	/*
6015 	 * If the inodes csum_bytes is the same as the original
6016 	 * csum_bytes then we know we haven't raced with any free()ers
6017 	 * so we can just reduce our inodes csum bytes and carry on.
6018 	 */
6019 	if (BTRFS_I(inode)->csum_bytes == csum_bytes) {
6020 		calc_csum_metadata_size(inode, num_bytes, 0);
6021 	} else {
6022 		u64 orig_csum_bytes = BTRFS_I(inode)->csum_bytes;
6023 		u64 bytes;
6024 
6025 		/*
6026 		 * This is tricky, but first we need to figure out how much we
6027 		 * freed from any free-ers that occurred during this
6028 		 * reservation, so we reset ->csum_bytes to the csum_bytes
6029 		 * before we dropped our lock, and then call the free for the
6030 		 * number of bytes that were freed while we were trying our
6031 		 * reservation.
6032 		 */
6033 		bytes = csum_bytes - BTRFS_I(inode)->csum_bytes;
6034 		BTRFS_I(inode)->csum_bytes = csum_bytes;
6035 		to_free = calc_csum_metadata_size(inode, bytes, 0);
6036 
6037 
6038 		/*
6039 		 * Now we need to see how much we would have freed had we not
6040 		 * been making this reservation and our ->csum_bytes were not
6041 		 * artificially inflated.
6042 		 */
6043 		BTRFS_I(inode)->csum_bytes = csum_bytes - num_bytes;
6044 		bytes = csum_bytes - orig_csum_bytes;
6045 		bytes = calc_csum_metadata_size(inode, bytes, 0);
6046 
6047 		/*
6048 		 * Now reset ->csum_bytes to what it should be.  If bytes is
6049 		 * more than to_free then we would have freed more space had we
6050 		 * not had an artificially high ->csum_bytes, so we need to free
6051 		 * the remainder.  If bytes is the same or less then we don't
6052 		 * need to do anything, the other free-ers did the correct
6053 		 * thing.
6054 		 */
6055 		BTRFS_I(inode)->csum_bytes = orig_csum_bytes - num_bytes;
6056 		if (bytes > to_free)
6057 			to_free = bytes - to_free;
6058 		else
6059 			to_free = 0;
6060 	}
6061 	spin_unlock(&BTRFS_I(inode)->lock);
6062 	if (dropped)
6063 		to_free += btrfs_calc_trans_metadata_size(fs_info, dropped);
6064 
6065 	if (to_free) {
6066 		btrfs_block_rsv_release(fs_info, block_rsv, to_free);
6067 		trace_btrfs_space_reservation(fs_info, "delalloc",
6068 					      btrfs_ino(inode), to_free, 0);
6069 	}
6070 	if (delalloc_lock)
6071 		mutex_unlock(&BTRFS_I(inode)->delalloc_mutex);
6072 	return ret;
6073 }
6074 
6075 /**
6076  * btrfs_delalloc_release_metadata - release a metadata reservation for an inode
6077  * @inode: the inode to release the reservation for
6078  * @num_bytes: the number of bytes we're releasing
6079  *
6080  * This will release the metadata reservation for an inode.  This can be called
6081  * once we complete IO for a given set of bytes to release their metadata
6082  * reservations.
6083  */
6084 void btrfs_delalloc_release_metadata(struct inode *inode, u64 num_bytes)
6085 {
6086 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
6087 	u64 to_free = 0;
6088 	unsigned dropped;
6089 
6090 	num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
6091 	spin_lock(&BTRFS_I(inode)->lock);
6092 	dropped = drop_outstanding_extent(inode, num_bytes);
6093 
6094 	if (num_bytes)
6095 		to_free = calc_csum_metadata_size(inode, num_bytes, 0);
6096 	spin_unlock(&BTRFS_I(inode)->lock);
6097 	if (dropped > 0)
6098 		to_free += btrfs_calc_trans_metadata_size(fs_info, dropped);
6099 
6100 	if (btrfs_is_testing(fs_info))
6101 		return;
6102 
6103 	trace_btrfs_space_reservation(fs_info, "delalloc",
6104 				      btrfs_ino(inode), to_free, 0);
6105 
6106 	btrfs_block_rsv_release(fs_info, &fs_info->delalloc_block_rsv, to_free);
6107 }
6108 
6109 /**
6110  * btrfs_delalloc_reserve_space - reserve data and metadata space for
6111  * delalloc
6112  * @inode: inode we're writing to
6113  * @start: start range we are writing to
6114  * @len: how long the range we are writing to
6115  *
6116  * This will do the following things
6117  *
6118  * o reserve space in data space info for num bytes
6119  *   and reserve precious corresponding qgroup space
6120  *   (Done in check_data_free_space)
6121  *
6122  * o reserve space for metadata space, based on the number of outstanding
6123  *   extents and how much csums will be needed
6124  *   also reserve metadata space in a per root over-reserve method.
6125  * o add to the inodes->delalloc_bytes
6126  * o add it to the fs_info's delalloc inodes list.
6127  *   (Above 3 all done in delalloc_reserve_metadata)
6128  *
6129  * Return 0 for success
6130  * Return <0 for error(-ENOSPC or -EQUOT)
6131  */
6132 int btrfs_delalloc_reserve_space(struct inode *inode, u64 start, u64 len)
6133 {
6134 	int ret;
6135 
6136 	ret = btrfs_check_data_free_space(inode, start, len);
6137 	if (ret < 0)
6138 		return ret;
6139 	ret = btrfs_delalloc_reserve_metadata(inode, len);
6140 	if (ret < 0)
6141 		btrfs_free_reserved_data_space(inode, start, len);
6142 	return ret;
6143 }
6144 
6145 /**
6146  * btrfs_delalloc_release_space - release data and metadata space for delalloc
6147  * @inode: inode we're releasing space for
6148  * @start: start position of the space already reserved
6149  * @len: the len of the space already reserved
6150  *
6151  * This must be matched with a call to btrfs_delalloc_reserve_space.  This is
6152  * called in the case that we don't need the metadata AND data reservations
6153  * anymore.  So if there is an error or we insert an inline extent.
6154  *
6155  * This function will release the metadata space that was not used and will
6156  * decrement ->delalloc_bytes and remove it from the fs_info delalloc_inodes
6157  * list if there are no delalloc bytes left.
6158  * Also it will handle the qgroup reserved space.
6159  */
6160 void btrfs_delalloc_release_space(struct inode *inode, u64 start, u64 len)
6161 {
6162 	btrfs_delalloc_release_metadata(inode, len);
6163 	btrfs_free_reserved_data_space(inode, start, len);
6164 }
6165 
6166 static int update_block_group(struct btrfs_trans_handle *trans,
6167 			      struct btrfs_fs_info *info, u64 bytenr,
6168 			      u64 num_bytes, int alloc)
6169 {
6170 	struct btrfs_block_group_cache *cache = NULL;
6171 	u64 total = num_bytes;
6172 	u64 old_val;
6173 	u64 byte_in_group;
6174 	int factor;
6175 
6176 	/* block accounting for super block */
6177 	spin_lock(&info->delalloc_root_lock);
6178 	old_val = btrfs_super_bytes_used(info->super_copy);
6179 	if (alloc)
6180 		old_val += num_bytes;
6181 	else
6182 		old_val -= num_bytes;
6183 	btrfs_set_super_bytes_used(info->super_copy, old_val);
6184 	spin_unlock(&info->delalloc_root_lock);
6185 
6186 	while (total) {
6187 		cache = btrfs_lookup_block_group(info, bytenr);
6188 		if (!cache)
6189 			return -ENOENT;
6190 		if (cache->flags & (BTRFS_BLOCK_GROUP_DUP |
6191 				    BTRFS_BLOCK_GROUP_RAID1 |
6192 				    BTRFS_BLOCK_GROUP_RAID10))
6193 			factor = 2;
6194 		else
6195 			factor = 1;
6196 		/*
6197 		 * If this block group has free space cache written out, we
6198 		 * need to make sure to load it if we are removing space.  This
6199 		 * is because we need the unpinning stage to actually add the
6200 		 * space back to the block group, otherwise we will leak space.
6201 		 */
6202 		if (!alloc && cache->cached == BTRFS_CACHE_NO)
6203 			cache_block_group(cache, 1);
6204 
6205 		byte_in_group = bytenr - cache->key.objectid;
6206 		WARN_ON(byte_in_group > cache->key.offset);
6207 
6208 		spin_lock(&cache->space_info->lock);
6209 		spin_lock(&cache->lock);
6210 
6211 		if (btrfs_test_opt(info, SPACE_CACHE) &&
6212 		    cache->disk_cache_state < BTRFS_DC_CLEAR)
6213 			cache->disk_cache_state = BTRFS_DC_CLEAR;
6214 
6215 		old_val = btrfs_block_group_used(&cache->item);
6216 		num_bytes = min(total, cache->key.offset - byte_in_group);
6217 		if (alloc) {
6218 			old_val += num_bytes;
6219 			btrfs_set_block_group_used(&cache->item, old_val);
6220 			cache->reserved -= num_bytes;
6221 			cache->space_info->bytes_reserved -= num_bytes;
6222 			cache->space_info->bytes_used += num_bytes;
6223 			cache->space_info->disk_used += num_bytes * factor;
6224 			spin_unlock(&cache->lock);
6225 			spin_unlock(&cache->space_info->lock);
6226 		} else {
6227 			old_val -= num_bytes;
6228 			btrfs_set_block_group_used(&cache->item, old_val);
6229 			cache->pinned += num_bytes;
6230 			cache->space_info->bytes_pinned += num_bytes;
6231 			cache->space_info->bytes_used -= num_bytes;
6232 			cache->space_info->disk_used -= num_bytes * factor;
6233 			spin_unlock(&cache->lock);
6234 			spin_unlock(&cache->space_info->lock);
6235 
6236 			trace_btrfs_space_reservation(info, "pinned",
6237 						      cache->space_info->flags,
6238 						      num_bytes, 1);
6239 			set_extent_dirty(info->pinned_extents,
6240 					 bytenr, bytenr + num_bytes - 1,
6241 					 GFP_NOFS | __GFP_NOFAIL);
6242 		}
6243 
6244 		spin_lock(&trans->transaction->dirty_bgs_lock);
6245 		if (list_empty(&cache->dirty_list)) {
6246 			list_add_tail(&cache->dirty_list,
6247 				      &trans->transaction->dirty_bgs);
6248 				trans->transaction->num_dirty_bgs++;
6249 			btrfs_get_block_group(cache);
6250 		}
6251 		spin_unlock(&trans->transaction->dirty_bgs_lock);
6252 
6253 		/*
6254 		 * No longer have used bytes in this block group, queue it for
6255 		 * deletion. We do this after adding the block group to the
6256 		 * dirty list to avoid races between cleaner kthread and space
6257 		 * cache writeout.
6258 		 */
6259 		if (!alloc && old_val == 0) {
6260 			spin_lock(&info->unused_bgs_lock);
6261 			if (list_empty(&cache->bg_list)) {
6262 				btrfs_get_block_group(cache);
6263 				list_add_tail(&cache->bg_list,
6264 					      &info->unused_bgs);
6265 			}
6266 			spin_unlock(&info->unused_bgs_lock);
6267 		}
6268 
6269 		btrfs_put_block_group(cache);
6270 		total -= num_bytes;
6271 		bytenr += num_bytes;
6272 	}
6273 	return 0;
6274 }
6275 
6276 static u64 first_logical_byte(struct btrfs_fs_info *fs_info, u64 search_start)
6277 {
6278 	struct btrfs_block_group_cache *cache;
6279 	u64 bytenr;
6280 
6281 	spin_lock(&fs_info->block_group_cache_lock);
6282 	bytenr = fs_info->first_logical_byte;
6283 	spin_unlock(&fs_info->block_group_cache_lock);
6284 
6285 	if (bytenr < (u64)-1)
6286 		return bytenr;
6287 
6288 	cache = btrfs_lookup_first_block_group(fs_info, search_start);
6289 	if (!cache)
6290 		return 0;
6291 
6292 	bytenr = cache->key.objectid;
6293 	btrfs_put_block_group(cache);
6294 
6295 	return bytenr;
6296 }
6297 
6298 static int pin_down_extent(struct btrfs_fs_info *fs_info,
6299 			   struct btrfs_block_group_cache *cache,
6300 			   u64 bytenr, u64 num_bytes, int reserved)
6301 {
6302 	spin_lock(&cache->space_info->lock);
6303 	spin_lock(&cache->lock);
6304 	cache->pinned += num_bytes;
6305 	cache->space_info->bytes_pinned += num_bytes;
6306 	if (reserved) {
6307 		cache->reserved -= num_bytes;
6308 		cache->space_info->bytes_reserved -= num_bytes;
6309 	}
6310 	spin_unlock(&cache->lock);
6311 	spin_unlock(&cache->space_info->lock);
6312 
6313 	trace_btrfs_space_reservation(fs_info, "pinned",
6314 				      cache->space_info->flags, num_bytes, 1);
6315 	set_extent_dirty(fs_info->pinned_extents, bytenr,
6316 			 bytenr + num_bytes - 1, GFP_NOFS | __GFP_NOFAIL);
6317 	return 0;
6318 }
6319 
6320 /*
6321  * this function must be called within transaction
6322  */
6323 int btrfs_pin_extent(struct btrfs_fs_info *fs_info,
6324 		     u64 bytenr, u64 num_bytes, int reserved)
6325 {
6326 	struct btrfs_block_group_cache *cache;
6327 
6328 	cache = btrfs_lookup_block_group(fs_info, bytenr);
6329 	BUG_ON(!cache); /* Logic error */
6330 
6331 	pin_down_extent(fs_info, cache, bytenr, num_bytes, reserved);
6332 
6333 	btrfs_put_block_group(cache);
6334 	return 0;
6335 }
6336 
6337 /*
6338  * this function must be called within transaction
6339  */
6340 int btrfs_pin_extent_for_log_replay(struct btrfs_fs_info *fs_info,
6341 				    u64 bytenr, u64 num_bytes)
6342 {
6343 	struct btrfs_block_group_cache *cache;
6344 	int ret;
6345 
6346 	cache = btrfs_lookup_block_group(fs_info, bytenr);
6347 	if (!cache)
6348 		return -EINVAL;
6349 
6350 	/*
6351 	 * pull in the free space cache (if any) so that our pin
6352 	 * removes the free space from the cache.  We have load_only set
6353 	 * to one because the slow code to read in the free extents does check
6354 	 * the pinned extents.
6355 	 */
6356 	cache_block_group(cache, 1);
6357 
6358 	pin_down_extent(fs_info, cache, bytenr, num_bytes, 0);
6359 
6360 	/* remove us from the free space cache (if we're there at all) */
6361 	ret = btrfs_remove_free_space(cache, bytenr, num_bytes);
6362 	btrfs_put_block_group(cache);
6363 	return ret;
6364 }
6365 
6366 static int __exclude_logged_extent(struct btrfs_fs_info *fs_info,
6367 				   u64 start, u64 num_bytes)
6368 {
6369 	int ret;
6370 	struct btrfs_block_group_cache *block_group;
6371 	struct btrfs_caching_control *caching_ctl;
6372 
6373 	block_group = btrfs_lookup_block_group(fs_info, start);
6374 	if (!block_group)
6375 		return -EINVAL;
6376 
6377 	cache_block_group(block_group, 0);
6378 	caching_ctl = get_caching_control(block_group);
6379 
6380 	if (!caching_ctl) {
6381 		/* Logic error */
6382 		BUG_ON(!block_group_cache_done(block_group));
6383 		ret = btrfs_remove_free_space(block_group, start, num_bytes);
6384 	} else {
6385 		mutex_lock(&caching_ctl->mutex);
6386 
6387 		if (start >= caching_ctl->progress) {
6388 			ret = add_excluded_extent(fs_info, start, num_bytes);
6389 		} else if (start + num_bytes <= caching_ctl->progress) {
6390 			ret = btrfs_remove_free_space(block_group,
6391 						      start, num_bytes);
6392 		} else {
6393 			num_bytes = caching_ctl->progress - start;
6394 			ret = btrfs_remove_free_space(block_group,
6395 						      start, num_bytes);
6396 			if (ret)
6397 				goto out_lock;
6398 
6399 			num_bytes = (start + num_bytes) -
6400 				caching_ctl->progress;
6401 			start = caching_ctl->progress;
6402 			ret = add_excluded_extent(fs_info, start, num_bytes);
6403 		}
6404 out_lock:
6405 		mutex_unlock(&caching_ctl->mutex);
6406 		put_caching_control(caching_ctl);
6407 	}
6408 	btrfs_put_block_group(block_group);
6409 	return ret;
6410 }
6411 
6412 int btrfs_exclude_logged_extents(struct btrfs_fs_info *fs_info,
6413 				 struct extent_buffer *eb)
6414 {
6415 	struct btrfs_file_extent_item *item;
6416 	struct btrfs_key key;
6417 	int found_type;
6418 	int i;
6419 
6420 	if (!btrfs_fs_incompat(fs_info, MIXED_GROUPS))
6421 		return 0;
6422 
6423 	for (i = 0; i < btrfs_header_nritems(eb); i++) {
6424 		btrfs_item_key_to_cpu(eb, &key, i);
6425 		if (key.type != BTRFS_EXTENT_DATA_KEY)
6426 			continue;
6427 		item = btrfs_item_ptr(eb, i, struct btrfs_file_extent_item);
6428 		found_type = btrfs_file_extent_type(eb, item);
6429 		if (found_type == BTRFS_FILE_EXTENT_INLINE)
6430 			continue;
6431 		if (btrfs_file_extent_disk_bytenr(eb, item) == 0)
6432 			continue;
6433 		key.objectid = btrfs_file_extent_disk_bytenr(eb, item);
6434 		key.offset = btrfs_file_extent_disk_num_bytes(eb, item);
6435 		__exclude_logged_extent(fs_info, key.objectid, key.offset);
6436 	}
6437 
6438 	return 0;
6439 }
6440 
6441 static void
6442 btrfs_inc_block_group_reservations(struct btrfs_block_group_cache *bg)
6443 {
6444 	atomic_inc(&bg->reservations);
6445 }
6446 
6447 void btrfs_dec_block_group_reservations(struct btrfs_fs_info *fs_info,
6448 					const u64 start)
6449 {
6450 	struct btrfs_block_group_cache *bg;
6451 
6452 	bg = btrfs_lookup_block_group(fs_info, start);
6453 	ASSERT(bg);
6454 	if (atomic_dec_and_test(&bg->reservations))
6455 		wake_up_atomic_t(&bg->reservations);
6456 	btrfs_put_block_group(bg);
6457 }
6458 
6459 static int btrfs_wait_bg_reservations_atomic_t(atomic_t *a)
6460 {
6461 	schedule();
6462 	return 0;
6463 }
6464 
6465 void btrfs_wait_block_group_reservations(struct btrfs_block_group_cache *bg)
6466 {
6467 	struct btrfs_space_info *space_info = bg->space_info;
6468 
6469 	ASSERT(bg->ro);
6470 
6471 	if (!(bg->flags & BTRFS_BLOCK_GROUP_DATA))
6472 		return;
6473 
6474 	/*
6475 	 * Our block group is read only but before we set it to read only,
6476 	 * some task might have had allocated an extent from it already, but it
6477 	 * has not yet created a respective ordered extent (and added it to a
6478 	 * root's list of ordered extents).
6479 	 * Therefore wait for any task currently allocating extents, since the
6480 	 * block group's reservations counter is incremented while a read lock
6481 	 * on the groups' semaphore is held and decremented after releasing
6482 	 * the read access on that semaphore and creating the ordered extent.
6483 	 */
6484 	down_write(&space_info->groups_sem);
6485 	up_write(&space_info->groups_sem);
6486 
6487 	wait_on_atomic_t(&bg->reservations,
6488 			 btrfs_wait_bg_reservations_atomic_t,
6489 			 TASK_UNINTERRUPTIBLE);
6490 }
6491 
6492 /**
6493  * btrfs_add_reserved_bytes - update the block_group and space info counters
6494  * @cache:	The cache we are manipulating
6495  * @ram_bytes:  The number of bytes of file content, and will be same to
6496  *              @num_bytes except for the compress path.
6497  * @num_bytes:	The number of bytes in question
6498  * @delalloc:   The blocks are allocated for the delalloc write
6499  *
6500  * This is called by the allocator when it reserves space. If this is a
6501  * reservation and the block group has become read only we cannot make the
6502  * reservation and return -EAGAIN, otherwise this function always succeeds.
6503  */
6504 static int btrfs_add_reserved_bytes(struct btrfs_block_group_cache *cache,
6505 				    u64 ram_bytes, u64 num_bytes, int delalloc)
6506 {
6507 	struct btrfs_space_info *space_info = cache->space_info;
6508 	int ret = 0;
6509 
6510 	spin_lock(&space_info->lock);
6511 	spin_lock(&cache->lock);
6512 	if (cache->ro) {
6513 		ret = -EAGAIN;
6514 	} else {
6515 		cache->reserved += num_bytes;
6516 		space_info->bytes_reserved += num_bytes;
6517 
6518 		trace_btrfs_space_reservation(cache->fs_info,
6519 				"space_info", space_info->flags,
6520 				ram_bytes, 0);
6521 		space_info->bytes_may_use -= ram_bytes;
6522 		if (delalloc)
6523 			cache->delalloc_bytes += num_bytes;
6524 	}
6525 	spin_unlock(&cache->lock);
6526 	spin_unlock(&space_info->lock);
6527 	return ret;
6528 }
6529 
6530 /**
6531  * btrfs_free_reserved_bytes - update the block_group and space info counters
6532  * @cache:      The cache we are manipulating
6533  * @num_bytes:  The number of bytes in question
6534  * @delalloc:   The blocks are allocated for the delalloc write
6535  *
6536  * This is called by somebody who is freeing space that was never actually used
6537  * on disk.  For example if you reserve some space for a new leaf in transaction
6538  * A and before transaction A commits you free that leaf, you call this with
6539  * reserve set to 0 in order to clear the reservation.
6540  */
6541 
6542 static int btrfs_free_reserved_bytes(struct btrfs_block_group_cache *cache,
6543 				     u64 num_bytes, int delalloc)
6544 {
6545 	struct btrfs_space_info *space_info = cache->space_info;
6546 	int ret = 0;
6547 
6548 	spin_lock(&space_info->lock);
6549 	spin_lock(&cache->lock);
6550 	if (cache->ro)
6551 		space_info->bytes_readonly += num_bytes;
6552 	cache->reserved -= num_bytes;
6553 	space_info->bytes_reserved -= num_bytes;
6554 
6555 	if (delalloc)
6556 		cache->delalloc_bytes -= num_bytes;
6557 	spin_unlock(&cache->lock);
6558 	spin_unlock(&space_info->lock);
6559 	return ret;
6560 }
6561 void btrfs_prepare_extent_commit(struct btrfs_trans_handle *trans,
6562 				struct btrfs_fs_info *fs_info)
6563 {
6564 	struct btrfs_caching_control *next;
6565 	struct btrfs_caching_control *caching_ctl;
6566 	struct btrfs_block_group_cache *cache;
6567 
6568 	down_write(&fs_info->commit_root_sem);
6569 
6570 	list_for_each_entry_safe(caching_ctl, next,
6571 				 &fs_info->caching_block_groups, list) {
6572 		cache = caching_ctl->block_group;
6573 		if (block_group_cache_done(cache)) {
6574 			cache->last_byte_to_unpin = (u64)-1;
6575 			list_del_init(&caching_ctl->list);
6576 			put_caching_control(caching_ctl);
6577 		} else {
6578 			cache->last_byte_to_unpin = caching_ctl->progress;
6579 		}
6580 	}
6581 
6582 	if (fs_info->pinned_extents == &fs_info->freed_extents[0])
6583 		fs_info->pinned_extents = &fs_info->freed_extents[1];
6584 	else
6585 		fs_info->pinned_extents = &fs_info->freed_extents[0];
6586 
6587 	up_write(&fs_info->commit_root_sem);
6588 
6589 	update_global_block_rsv(fs_info);
6590 }
6591 
6592 /*
6593  * Returns the free cluster for the given space info and sets empty_cluster to
6594  * what it should be based on the mount options.
6595  */
6596 static struct btrfs_free_cluster *
6597 fetch_cluster_info(struct btrfs_fs_info *fs_info,
6598 		   struct btrfs_space_info *space_info, u64 *empty_cluster)
6599 {
6600 	struct btrfs_free_cluster *ret = NULL;
6601 	bool ssd = btrfs_test_opt(fs_info, SSD);
6602 
6603 	*empty_cluster = 0;
6604 	if (btrfs_mixed_space_info(space_info))
6605 		return ret;
6606 
6607 	if (ssd)
6608 		*empty_cluster = SZ_2M;
6609 	if (space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
6610 		ret = &fs_info->meta_alloc_cluster;
6611 		if (!ssd)
6612 			*empty_cluster = SZ_64K;
6613 	} else if ((space_info->flags & BTRFS_BLOCK_GROUP_DATA) && ssd) {
6614 		ret = &fs_info->data_alloc_cluster;
6615 	}
6616 
6617 	return ret;
6618 }
6619 
6620 static int unpin_extent_range(struct btrfs_fs_info *fs_info,
6621 			      u64 start, u64 end,
6622 			      const bool return_free_space)
6623 {
6624 	struct btrfs_block_group_cache *cache = NULL;
6625 	struct btrfs_space_info *space_info;
6626 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
6627 	struct btrfs_free_cluster *cluster = NULL;
6628 	u64 len;
6629 	u64 total_unpinned = 0;
6630 	u64 empty_cluster = 0;
6631 	bool readonly;
6632 
6633 	while (start <= end) {
6634 		readonly = false;
6635 		if (!cache ||
6636 		    start >= cache->key.objectid + cache->key.offset) {
6637 			if (cache)
6638 				btrfs_put_block_group(cache);
6639 			total_unpinned = 0;
6640 			cache = btrfs_lookup_block_group(fs_info, start);
6641 			BUG_ON(!cache); /* Logic error */
6642 
6643 			cluster = fetch_cluster_info(fs_info,
6644 						     cache->space_info,
6645 						     &empty_cluster);
6646 			empty_cluster <<= 1;
6647 		}
6648 
6649 		len = cache->key.objectid + cache->key.offset - start;
6650 		len = min(len, end + 1 - start);
6651 
6652 		if (start < cache->last_byte_to_unpin) {
6653 			len = min(len, cache->last_byte_to_unpin - start);
6654 			if (return_free_space)
6655 				btrfs_add_free_space(cache, start, len);
6656 		}
6657 
6658 		start += len;
6659 		total_unpinned += len;
6660 		space_info = cache->space_info;
6661 
6662 		/*
6663 		 * If this space cluster has been marked as fragmented and we've
6664 		 * unpinned enough in this block group to potentially allow a
6665 		 * cluster to be created inside of it go ahead and clear the
6666 		 * fragmented check.
6667 		 */
6668 		if (cluster && cluster->fragmented &&
6669 		    total_unpinned > empty_cluster) {
6670 			spin_lock(&cluster->lock);
6671 			cluster->fragmented = 0;
6672 			spin_unlock(&cluster->lock);
6673 		}
6674 
6675 		spin_lock(&space_info->lock);
6676 		spin_lock(&cache->lock);
6677 		cache->pinned -= len;
6678 		space_info->bytes_pinned -= len;
6679 
6680 		trace_btrfs_space_reservation(fs_info, "pinned",
6681 					      space_info->flags, len, 0);
6682 		space_info->max_extent_size = 0;
6683 		percpu_counter_add(&space_info->total_bytes_pinned, -len);
6684 		if (cache->ro) {
6685 			space_info->bytes_readonly += len;
6686 			readonly = true;
6687 		}
6688 		spin_unlock(&cache->lock);
6689 		if (!readonly && return_free_space &&
6690 		    global_rsv->space_info == space_info) {
6691 			u64 to_add = len;
6692 			WARN_ON(!return_free_space);
6693 			spin_lock(&global_rsv->lock);
6694 			if (!global_rsv->full) {
6695 				to_add = min(len, global_rsv->size -
6696 					     global_rsv->reserved);
6697 				global_rsv->reserved += to_add;
6698 				space_info->bytes_may_use += to_add;
6699 				if (global_rsv->reserved >= global_rsv->size)
6700 					global_rsv->full = 1;
6701 				trace_btrfs_space_reservation(fs_info,
6702 							      "space_info",
6703 							      space_info->flags,
6704 							      to_add, 1);
6705 				len -= to_add;
6706 			}
6707 			spin_unlock(&global_rsv->lock);
6708 			/* Add to any tickets we may have */
6709 			if (len)
6710 				space_info_add_new_bytes(fs_info, space_info,
6711 							 len);
6712 		}
6713 		spin_unlock(&space_info->lock);
6714 	}
6715 
6716 	if (cache)
6717 		btrfs_put_block_group(cache);
6718 	return 0;
6719 }
6720 
6721 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
6722 			       struct btrfs_fs_info *fs_info)
6723 {
6724 	struct btrfs_block_group_cache *block_group, *tmp;
6725 	struct list_head *deleted_bgs;
6726 	struct extent_io_tree *unpin;
6727 	u64 start;
6728 	u64 end;
6729 	int ret;
6730 
6731 	if (fs_info->pinned_extents == &fs_info->freed_extents[0])
6732 		unpin = &fs_info->freed_extents[1];
6733 	else
6734 		unpin = &fs_info->freed_extents[0];
6735 
6736 	while (!trans->aborted) {
6737 		mutex_lock(&fs_info->unused_bg_unpin_mutex);
6738 		ret = find_first_extent_bit(unpin, 0, &start, &end,
6739 					    EXTENT_DIRTY, NULL);
6740 		if (ret) {
6741 			mutex_unlock(&fs_info->unused_bg_unpin_mutex);
6742 			break;
6743 		}
6744 
6745 		if (btrfs_test_opt(fs_info, DISCARD))
6746 			ret = btrfs_discard_extent(fs_info, start,
6747 						   end + 1 - start, NULL);
6748 
6749 		clear_extent_dirty(unpin, start, end);
6750 		unpin_extent_range(fs_info, start, end, true);
6751 		mutex_unlock(&fs_info->unused_bg_unpin_mutex);
6752 		cond_resched();
6753 	}
6754 
6755 	/*
6756 	 * Transaction is finished.  We don't need the lock anymore.  We
6757 	 * do need to clean up the block groups in case of a transaction
6758 	 * abort.
6759 	 */
6760 	deleted_bgs = &trans->transaction->deleted_bgs;
6761 	list_for_each_entry_safe(block_group, tmp, deleted_bgs, bg_list) {
6762 		u64 trimmed = 0;
6763 
6764 		ret = -EROFS;
6765 		if (!trans->aborted)
6766 			ret = btrfs_discard_extent(fs_info,
6767 						   block_group->key.objectid,
6768 						   block_group->key.offset,
6769 						   &trimmed);
6770 
6771 		list_del_init(&block_group->bg_list);
6772 		btrfs_put_block_group_trimming(block_group);
6773 		btrfs_put_block_group(block_group);
6774 
6775 		if (ret) {
6776 			const char *errstr = btrfs_decode_error(ret);
6777 			btrfs_warn(fs_info,
6778 				   "Discard failed while removing blockgroup: errno=%d %s\n",
6779 				   ret, errstr);
6780 		}
6781 	}
6782 
6783 	return 0;
6784 }
6785 
6786 static void add_pinned_bytes(struct btrfs_fs_info *fs_info, u64 num_bytes,
6787 			     u64 owner, u64 root_objectid)
6788 {
6789 	struct btrfs_space_info *space_info;
6790 	u64 flags;
6791 
6792 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
6793 		if (root_objectid == BTRFS_CHUNK_TREE_OBJECTID)
6794 			flags = BTRFS_BLOCK_GROUP_SYSTEM;
6795 		else
6796 			flags = BTRFS_BLOCK_GROUP_METADATA;
6797 	} else {
6798 		flags = BTRFS_BLOCK_GROUP_DATA;
6799 	}
6800 
6801 	space_info = __find_space_info(fs_info, flags);
6802 	BUG_ON(!space_info); /* Logic bug */
6803 	percpu_counter_add(&space_info->total_bytes_pinned, num_bytes);
6804 }
6805 
6806 
6807 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
6808 				struct btrfs_fs_info *info,
6809 				struct btrfs_delayed_ref_node *node, u64 parent,
6810 				u64 root_objectid, u64 owner_objectid,
6811 				u64 owner_offset, int refs_to_drop,
6812 				struct btrfs_delayed_extent_op *extent_op)
6813 {
6814 	struct btrfs_key key;
6815 	struct btrfs_path *path;
6816 	struct btrfs_root *extent_root = info->extent_root;
6817 	struct extent_buffer *leaf;
6818 	struct btrfs_extent_item *ei;
6819 	struct btrfs_extent_inline_ref *iref;
6820 	int ret;
6821 	int is_data;
6822 	int extent_slot = 0;
6823 	int found_extent = 0;
6824 	int num_to_del = 1;
6825 	u32 item_size;
6826 	u64 refs;
6827 	u64 bytenr = node->bytenr;
6828 	u64 num_bytes = node->num_bytes;
6829 	int last_ref = 0;
6830 	bool skinny_metadata = btrfs_fs_incompat(info, SKINNY_METADATA);
6831 
6832 	path = btrfs_alloc_path();
6833 	if (!path)
6834 		return -ENOMEM;
6835 
6836 	path->reada = READA_FORWARD;
6837 	path->leave_spinning = 1;
6838 
6839 	is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
6840 	BUG_ON(!is_data && refs_to_drop != 1);
6841 
6842 	if (is_data)
6843 		skinny_metadata = 0;
6844 
6845 	ret = lookup_extent_backref(trans, extent_root, path, &iref,
6846 				    bytenr, num_bytes, parent,
6847 				    root_objectid, owner_objectid,
6848 				    owner_offset);
6849 	if (ret == 0) {
6850 		extent_slot = path->slots[0];
6851 		while (extent_slot >= 0) {
6852 			btrfs_item_key_to_cpu(path->nodes[0], &key,
6853 					      extent_slot);
6854 			if (key.objectid != bytenr)
6855 				break;
6856 			if (key.type == BTRFS_EXTENT_ITEM_KEY &&
6857 			    key.offset == num_bytes) {
6858 				found_extent = 1;
6859 				break;
6860 			}
6861 			if (key.type == BTRFS_METADATA_ITEM_KEY &&
6862 			    key.offset == owner_objectid) {
6863 				found_extent = 1;
6864 				break;
6865 			}
6866 			if (path->slots[0] - extent_slot > 5)
6867 				break;
6868 			extent_slot--;
6869 		}
6870 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
6871 		item_size = btrfs_item_size_nr(path->nodes[0], extent_slot);
6872 		if (found_extent && item_size < sizeof(*ei))
6873 			found_extent = 0;
6874 #endif
6875 		if (!found_extent) {
6876 			BUG_ON(iref);
6877 			ret = remove_extent_backref(trans, extent_root, path,
6878 						    NULL, refs_to_drop,
6879 						    is_data, &last_ref);
6880 			if (ret) {
6881 				btrfs_abort_transaction(trans, ret);
6882 				goto out;
6883 			}
6884 			btrfs_release_path(path);
6885 			path->leave_spinning = 1;
6886 
6887 			key.objectid = bytenr;
6888 			key.type = BTRFS_EXTENT_ITEM_KEY;
6889 			key.offset = num_bytes;
6890 
6891 			if (!is_data && skinny_metadata) {
6892 				key.type = BTRFS_METADATA_ITEM_KEY;
6893 				key.offset = owner_objectid;
6894 			}
6895 
6896 			ret = btrfs_search_slot(trans, extent_root,
6897 						&key, path, -1, 1);
6898 			if (ret > 0 && skinny_metadata && path->slots[0]) {
6899 				/*
6900 				 * Couldn't find our skinny metadata item,
6901 				 * see if we have ye olde extent item.
6902 				 */
6903 				path->slots[0]--;
6904 				btrfs_item_key_to_cpu(path->nodes[0], &key,
6905 						      path->slots[0]);
6906 				if (key.objectid == bytenr &&
6907 				    key.type == BTRFS_EXTENT_ITEM_KEY &&
6908 				    key.offset == num_bytes)
6909 					ret = 0;
6910 			}
6911 
6912 			if (ret > 0 && skinny_metadata) {
6913 				skinny_metadata = false;
6914 				key.objectid = bytenr;
6915 				key.type = BTRFS_EXTENT_ITEM_KEY;
6916 				key.offset = num_bytes;
6917 				btrfs_release_path(path);
6918 				ret = btrfs_search_slot(trans, extent_root,
6919 							&key, path, -1, 1);
6920 			}
6921 
6922 			if (ret) {
6923 				btrfs_err(info,
6924 					  "umm, got %d back from search, was looking for %llu",
6925 					  ret, bytenr);
6926 				if (ret > 0)
6927 					btrfs_print_leaf(info, path->nodes[0]);
6928 			}
6929 			if (ret < 0) {
6930 				btrfs_abort_transaction(trans, ret);
6931 				goto out;
6932 			}
6933 			extent_slot = path->slots[0];
6934 		}
6935 	} else if (WARN_ON(ret == -ENOENT)) {
6936 		btrfs_print_leaf(info, path->nodes[0]);
6937 		btrfs_err(info,
6938 			"unable to find ref byte nr %llu parent %llu root %llu  owner %llu offset %llu",
6939 			bytenr, parent, root_objectid, owner_objectid,
6940 			owner_offset);
6941 		btrfs_abort_transaction(trans, ret);
6942 		goto out;
6943 	} else {
6944 		btrfs_abort_transaction(trans, ret);
6945 		goto out;
6946 	}
6947 
6948 	leaf = path->nodes[0];
6949 	item_size = btrfs_item_size_nr(leaf, extent_slot);
6950 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
6951 	if (item_size < sizeof(*ei)) {
6952 		BUG_ON(found_extent || extent_slot != path->slots[0]);
6953 		ret = convert_extent_item_v0(trans, extent_root, path,
6954 					     owner_objectid, 0);
6955 		if (ret < 0) {
6956 			btrfs_abort_transaction(trans, ret);
6957 			goto out;
6958 		}
6959 
6960 		btrfs_release_path(path);
6961 		path->leave_spinning = 1;
6962 
6963 		key.objectid = bytenr;
6964 		key.type = BTRFS_EXTENT_ITEM_KEY;
6965 		key.offset = num_bytes;
6966 
6967 		ret = btrfs_search_slot(trans, extent_root, &key, path,
6968 					-1, 1);
6969 		if (ret) {
6970 			btrfs_err(info,
6971 				  "umm, got %d back from search, was looking for %llu",
6972 				ret, bytenr);
6973 			btrfs_print_leaf(info, path->nodes[0]);
6974 		}
6975 		if (ret < 0) {
6976 			btrfs_abort_transaction(trans, ret);
6977 			goto out;
6978 		}
6979 
6980 		extent_slot = path->slots[0];
6981 		leaf = path->nodes[0];
6982 		item_size = btrfs_item_size_nr(leaf, extent_slot);
6983 	}
6984 #endif
6985 	BUG_ON(item_size < sizeof(*ei));
6986 	ei = btrfs_item_ptr(leaf, extent_slot,
6987 			    struct btrfs_extent_item);
6988 	if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID &&
6989 	    key.type == BTRFS_EXTENT_ITEM_KEY) {
6990 		struct btrfs_tree_block_info *bi;
6991 		BUG_ON(item_size < sizeof(*ei) + sizeof(*bi));
6992 		bi = (struct btrfs_tree_block_info *)(ei + 1);
6993 		WARN_ON(owner_objectid != btrfs_tree_block_level(leaf, bi));
6994 	}
6995 
6996 	refs = btrfs_extent_refs(leaf, ei);
6997 	if (refs < refs_to_drop) {
6998 		btrfs_err(info,
6999 			  "trying to drop %d refs but we only have %Lu for bytenr %Lu",
7000 			  refs_to_drop, refs, bytenr);
7001 		ret = -EINVAL;
7002 		btrfs_abort_transaction(trans, ret);
7003 		goto out;
7004 	}
7005 	refs -= refs_to_drop;
7006 
7007 	if (refs > 0) {
7008 		if (extent_op)
7009 			__run_delayed_extent_op(extent_op, leaf, ei);
7010 		/*
7011 		 * In the case of inline back ref, reference count will
7012 		 * be updated by remove_extent_backref
7013 		 */
7014 		if (iref) {
7015 			BUG_ON(!found_extent);
7016 		} else {
7017 			btrfs_set_extent_refs(leaf, ei, refs);
7018 			btrfs_mark_buffer_dirty(leaf);
7019 		}
7020 		if (found_extent) {
7021 			ret = remove_extent_backref(trans, extent_root, path,
7022 						    iref, refs_to_drop,
7023 						    is_data, &last_ref);
7024 			if (ret) {
7025 				btrfs_abort_transaction(trans, ret);
7026 				goto out;
7027 			}
7028 		}
7029 		add_pinned_bytes(info, -num_bytes, owner_objectid,
7030 				 root_objectid);
7031 	} else {
7032 		if (found_extent) {
7033 			BUG_ON(is_data && refs_to_drop !=
7034 			       extent_data_ref_count(path, iref));
7035 			if (iref) {
7036 				BUG_ON(path->slots[0] != extent_slot);
7037 			} else {
7038 				BUG_ON(path->slots[0] != extent_slot + 1);
7039 				path->slots[0] = extent_slot;
7040 				num_to_del = 2;
7041 			}
7042 		}
7043 
7044 		last_ref = 1;
7045 		ret = btrfs_del_items(trans, extent_root, path, path->slots[0],
7046 				      num_to_del);
7047 		if (ret) {
7048 			btrfs_abort_transaction(trans, ret);
7049 			goto out;
7050 		}
7051 		btrfs_release_path(path);
7052 
7053 		if (is_data) {
7054 			ret = btrfs_del_csums(trans, info, bytenr, num_bytes);
7055 			if (ret) {
7056 				btrfs_abort_transaction(trans, ret);
7057 				goto out;
7058 			}
7059 		}
7060 
7061 		ret = add_to_free_space_tree(trans, info, bytenr, num_bytes);
7062 		if (ret) {
7063 			btrfs_abort_transaction(trans, ret);
7064 			goto out;
7065 		}
7066 
7067 		ret = update_block_group(trans, info, bytenr, num_bytes, 0);
7068 		if (ret) {
7069 			btrfs_abort_transaction(trans, ret);
7070 			goto out;
7071 		}
7072 	}
7073 	btrfs_release_path(path);
7074 
7075 out:
7076 	btrfs_free_path(path);
7077 	return ret;
7078 }
7079 
7080 /*
7081  * when we free an block, it is possible (and likely) that we free the last
7082  * delayed ref for that extent as well.  This searches the delayed ref tree for
7083  * a given extent, and if there are no other delayed refs to be processed, it
7084  * removes it from the tree.
7085  */
7086 static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
7087 				      u64 bytenr)
7088 {
7089 	struct btrfs_delayed_ref_head *head;
7090 	struct btrfs_delayed_ref_root *delayed_refs;
7091 	int ret = 0;
7092 
7093 	delayed_refs = &trans->transaction->delayed_refs;
7094 	spin_lock(&delayed_refs->lock);
7095 	head = btrfs_find_delayed_ref_head(trans, bytenr);
7096 	if (!head)
7097 		goto out_delayed_unlock;
7098 
7099 	spin_lock(&head->lock);
7100 	if (!list_empty(&head->ref_list))
7101 		goto out;
7102 
7103 	if (head->extent_op) {
7104 		if (!head->must_insert_reserved)
7105 			goto out;
7106 		btrfs_free_delayed_extent_op(head->extent_op);
7107 		head->extent_op = NULL;
7108 	}
7109 
7110 	/*
7111 	 * waiting for the lock here would deadlock.  If someone else has it
7112 	 * locked they are already in the process of dropping it anyway
7113 	 */
7114 	if (!mutex_trylock(&head->mutex))
7115 		goto out;
7116 
7117 	/*
7118 	 * at this point we have a head with no other entries.  Go
7119 	 * ahead and process it.
7120 	 */
7121 	head->node.in_tree = 0;
7122 	rb_erase(&head->href_node, &delayed_refs->href_root);
7123 
7124 	atomic_dec(&delayed_refs->num_entries);
7125 
7126 	/*
7127 	 * we don't take a ref on the node because we're removing it from the
7128 	 * tree, so we just steal the ref the tree was holding.
7129 	 */
7130 	delayed_refs->num_heads--;
7131 	if (head->processing == 0)
7132 		delayed_refs->num_heads_ready--;
7133 	head->processing = 0;
7134 	spin_unlock(&head->lock);
7135 	spin_unlock(&delayed_refs->lock);
7136 
7137 	BUG_ON(head->extent_op);
7138 	if (head->must_insert_reserved)
7139 		ret = 1;
7140 
7141 	mutex_unlock(&head->mutex);
7142 	btrfs_put_delayed_ref(&head->node);
7143 	return ret;
7144 out:
7145 	spin_unlock(&head->lock);
7146 
7147 out_delayed_unlock:
7148 	spin_unlock(&delayed_refs->lock);
7149 	return 0;
7150 }
7151 
7152 void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
7153 			   struct btrfs_root *root,
7154 			   struct extent_buffer *buf,
7155 			   u64 parent, int last_ref)
7156 {
7157 	struct btrfs_fs_info *fs_info = root->fs_info;
7158 	int pin = 1;
7159 	int ret;
7160 
7161 	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
7162 		ret = btrfs_add_delayed_tree_ref(fs_info, trans,
7163 						 buf->start, buf->len,
7164 						 parent,
7165 						 root->root_key.objectid,
7166 						 btrfs_header_level(buf),
7167 						 BTRFS_DROP_DELAYED_REF, NULL);
7168 		BUG_ON(ret); /* -ENOMEM */
7169 	}
7170 
7171 	if (!last_ref)
7172 		return;
7173 
7174 	if (btrfs_header_generation(buf) == trans->transid) {
7175 		struct btrfs_block_group_cache *cache;
7176 
7177 		if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
7178 			ret = check_ref_cleanup(trans, buf->start);
7179 			if (!ret)
7180 				goto out;
7181 		}
7182 
7183 		cache = btrfs_lookup_block_group(fs_info, buf->start);
7184 
7185 		if (btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
7186 			pin_down_extent(fs_info, cache, buf->start,
7187 					buf->len, 1);
7188 			btrfs_put_block_group(cache);
7189 			goto out;
7190 		}
7191 
7192 		WARN_ON(test_bit(EXTENT_BUFFER_DIRTY, &buf->bflags));
7193 
7194 		btrfs_add_free_space(cache, buf->start, buf->len);
7195 		btrfs_free_reserved_bytes(cache, buf->len, 0);
7196 		btrfs_put_block_group(cache);
7197 		trace_btrfs_reserved_extent_free(fs_info, buf->start, buf->len);
7198 		pin = 0;
7199 	}
7200 out:
7201 	if (pin)
7202 		add_pinned_bytes(fs_info, buf->len, btrfs_header_level(buf),
7203 				 root->root_key.objectid);
7204 
7205 	/*
7206 	 * Deleting the buffer, clear the corrupt flag since it doesn't matter
7207 	 * anymore.
7208 	 */
7209 	clear_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags);
7210 }
7211 
7212 /* Can return -ENOMEM */
7213 int btrfs_free_extent(struct btrfs_trans_handle *trans,
7214 		      struct btrfs_fs_info *fs_info,
7215 		      u64 bytenr, u64 num_bytes, u64 parent, u64 root_objectid,
7216 		      u64 owner, u64 offset)
7217 {
7218 	int ret;
7219 
7220 	if (btrfs_is_testing(fs_info))
7221 		return 0;
7222 
7223 	add_pinned_bytes(fs_info, num_bytes, owner, root_objectid);
7224 
7225 	/*
7226 	 * tree log blocks never actually go into the extent allocation
7227 	 * tree, just update pinning info and exit early.
7228 	 */
7229 	if (root_objectid == BTRFS_TREE_LOG_OBJECTID) {
7230 		WARN_ON(owner >= BTRFS_FIRST_FREE_OBJECTID);
7231 		/* unlocks the pinned mutex */
7232 		btrfs_pin_extent(fs_info, bytenr, num_bytes, 1);
7233 		ret = 0;
7234 	} else if (owner < BTRFS_FIRST_FREE_OBJECTID) {
7235 		ret = btrfs_add_delayed_tree_ref(fs_info, trans, bytenr,
7236 					num_bytes,
7237 					parent, root_objectid, (int)owner,
7238 					BTRFS_DROP_DELAYED_REF, NULL);
7239 	} else {
7240 		ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
7241 						num_bytes,
7242 						parent, root_objectid, owner,
7243 						offset, 0,
7244 						BTRFS_DROP_DELAYED_REF, NULL);
7245 	}
7246 	return ret;
7247 }
7248 
7249 /*
7250  * when we wait for progress in the block group caching, its because
7251  * our allocation attempt failed at least once.  So, we must sleep
7252  * and let some progress happen before we try again.
7253  *
7254  * This function will sleep at least once waiting for new free space to
7255  * show up, and then it will check the block group free space numbers
7256  * for our min num_bytes.  Another option is to have it go ahead
7257  * and look in the rbtree for a free extent of a given size, but this
7258  * is a good start.
7259  *
7260  * Callers of this must check if cache->cached == BTRFS_CACHE_ERROR before using
7261  * any of the information in this block group.
7262  */
7263 static noinline void
7264 wait_block_group_cache_progress(struct btrfs_block_group_cache *cache,
7265 				u64 num_bytes)
7266 {
7267 	struct btrfs_caching_control *caching_ctl;
7268 
7269 	caching_ctl = get_caching_control(cache);
7270 	if (!caching_ctl)
7271 		return;
7272 
7273 	wait_event(caching_ctl->wait, block_group_cache_done(cache) ||
7274 		   (cache->free_space_ctl->free_space >= num_bytes));
7275 
7276 	put_caching_control(caching_ctl);
7277 }
7278 
7279 static noinline int
7280 wait_block_group_cache_done(struct btrfs_block_group_cache *cache)
7281 {
7282 	struct btrfs_caching_control *caching_ctl;
7283 	int ret = 0;
7284 
7285 	caching_ctl = get_caching_control(cache);
7286 	if (!caching_ctl)
7287 		return (cache->cached == BTRFS_CACHE_ERROR) ? -EIO : 0;
7288 
7289 	wait_event(caching_ctl->wait, block_group_cache_done(cache));
7290 	if (cache->cached == BTRFS_CACHE_ERROR)
7291 		ret = -EIO;
7292 	put_caching_control(caching_ctl);
7293 	return ret;
7294 }
7295 
7296 int __get_raid_index(u64 flags)
7297 {
7298 	if (flags & BTRFS_BLOCK_GROUP_RAID10)
7299 		return BTRFS_RAID_RAID10;
7300 	else if (flags & BTRFS_BLOCK_GROUP_RAID1)
7301 		return BTRFS_RAID_RAID1;
7302 	else if (flags & BTRFS_BLOCK_GROUP_DUP)
7303 		return BTRFS_RAID_DUP;
7304 	else if (flags & BTRFS_BLOCK_GROUP_RAID0)
7305 		return BTRFS_RAID_RAID0;
7306 	else if (flags & BTRFS_BLOCK_GROUP_RAID5)
7307 		return BTRFS_RAID_RAID5;
7308 	else if (flags & BTRFS_BLOCK_GROUP_RAID6)
7309 		return BTRFS_RAID_RAID6;
7310 
7311 	return BTRFS_RAID_SINGLE; /* BTRFS_BLOCK_GROUP_SINGLE */
7312 }
7313 
7314 int get_block_group_index(struct btrfs_block_group_cache *cache)
7315 {
7316 	return __get_raid_index(cache->flags);
7317 }
7318 
7319 static const char *btrfs_raid_type_names[BTRFS_NR_RAID_TYPES] = {
7320 	[BTRFS_RAID_RAID10]	= "raid10",
7321 	[BTRFS_RAID_RAID1]	= "raid1",
7322 	[BTRFS_RAID_DUP]	= "dup",
7323 	[BTRFS_RAID_RAID0]	= "raid0",
7324 	[BTRFS_RAID_SINGLE]	= "single",
7325 	[BTRFS_RAID_RAID5]	= "raid5",
7326 	[BTRFS_RAID_RAID6]	= "raid6",
7327 };
7328 
7329 static const char *get_raid_name(enum btrfs_raid_types type)
7330 {
7331 	if (type >= BTRFS_NR_RAID_TYPES)
7332 		return NULL;
7333 
7334 	return btrfs_raid_type_names[type];
7335 }
7336 
7337 enum btrfs_loop_type {
7338 	LOOP_CACHING_NOWAIT = 0,
7339 	LOOP_CACHING_WAIT = 1,
7340 	LOOP_ALLOC_CHUNK = 2,
7341 	LOOP_NO_EMPTY_SIZE = 3,
7342 };
7343 
7344 static inline void
7345 btrfs_lock_block_group(struct btrfs_block_group_cache *cache,
7346 		       int delalloc)
7347 {
7348 	if (delalloc)
7349 		down_read(&cache->data_rwsem);
7350 }
7351 
7352 static inline void
7353 btrfs_grab_block_group(struct btrfs_block_group_cache *cache,
7354 		       int delalloc)
7355 {
7356 	btrfs_get_block_group(cache);
7357 	if (delalloc)
7358 		down_read(&cache->data_rwsem);
7359 }
7360 
7361 static struct btrfs_block_group_cache *
7362 btrfs_lock_cluster(struct btrfs_block_group_cache *block_group,
7363 		   struct btrfs_free_cluster *cluster,
7364 		   int delalloc)
7365 {
7366 	struct btrfs_block_group_cache *used_bg = NULL;
7367 
7368 	spin_lock(&cluster->refill_lock);
7369 	while (1) {
7370 		used_bg = cluster->block_group;
7371 		if (!used_bg)
7372 			return NULL;
7373 
7374 		if (used_bg == block_group)
7375 			return used_bg;
7376 
7377 		btrfs_get_block_group(used_bg);
7378 
7379 		if (!delalloc)
7380 			return used_bg;
7381 
7382 		if (down_read_trylock(&used_bg->data_rwsem))
7383 			return used_bg;
7384 
7385 		spin_unlock(&cluster->refill_lock);
7386 
7387 		down_read(&used_bg->data_rwsem);
7388 
7389 		spin_lock(&cluster->refill_lock);
7390 		if (used_bg == cluster->block_group)
7391 			return used_bg;
7392 
7393 		up_read(&used_bg->data_rwsem);
7394 		btrfs_put_block_group(used_bg);
7395 	}
7396 }
7397 
7398 static inline void
7399 btrfs_release_block_group(struct btrfs_block_group_cache *cache,
7400 			 int delalloc)
7401 {
7402 	if (delalloc)
7403 		up_read(&cache->data_rwsem);
7404 	btrfs_put_block_group(cache);
7405 }
7406 
7407 /*
7408  * walks the btree of allocated extents and find a hole of a given size.
7409  * The key ins is changed to record the hole:
7410  * ins->objectid == start position
7411  * ins->flags = BTRFS_EXTENT_ITEM_KEY
7412  * ins->offset == the size of the hole.
7413  * Any available blocks before search_start are skipped.
7414  *
7415  * If there is no suitable free space, we will record the max size of
7416  * the free space extent currently.
7417  */
7418 static noinline int find_free_extent(struct btrfs_root *orig_root,
7419 				u64 ram_bytes, u64 num_bytes, u64 empty_size,
7420 				u64 hint_byte, struct btrfs_key *ins,
7421 				u64 flags, int delalloc)
7422 {
7423 	struct btrfs_fs_info *fs_info = orig_root->fs_info;
7424 	int ret = 0;
7425 	struct btrfs_root *root = fs_info->extent_root;
7426 	struct btrfs_free_cluster *last_ptr = NULL;
7427 	struct btrfs_block_group_cache *block_group = NULL;
7428 	u64 search_start = 0;
7429 	u64 max_extent_size = 0;
7430 	u64 empty_cluster = 0;
7431 	struct btrfs_space_info *space_info;
7432 	int loop = 0;
7433 	int index = __get_raid_index(flags);
7434 	bool failed_cluster_refill = false;
7435 	bool failed_alloc = false;
7436 	bool use_cluster = true;
7437 	bool have_caching_bg = false;
7438 	bool orig_have_caching_bg = false;
7439 	bool full_search = false;
7440 
7441 	WARN_ON(num_bytes < fs_info->sectorsize);
7442 	ins->type = BTRFS_EXTENT_ITEM_KEY;
7443 	ins->objectid = 0;
7444 	ins->offset = 0;
7445 
7446 	trace_find_free_extent(fs_info, num_bytes, empty_size, flags);
7447 
7448 	space_info = __find_space_info(fs_info, flags);
7449 	if (!space_info) {
7450 		btrfs_err(fs_info, "No space info for %llu", flags);
7451 		return -ENOSPC;
7452 	}
7453 
7454 	/*
7455 	 * If our free space is heavily fragmented we may not be able to make
7456 	 * big contiguous allocations, so instead of doing the expensive search
7457 	 * for free space, simply return ENOSPC with our max_extent_size so we
7458 	 * can go ahead and search for a more manageable chunk.
7459 	 *
7460 	 * If our max_extent_size is large enough for our allocation simply
7461 	 * disable clustering since we will likely not be able to find enough
7462 	 * space to create a cluster and induce latency trying.
7463 	 */
7464 	if (unlikely(space_info->max_extent_size)) {
7465 		spin_lock(&space_info->lock);
7466 		if (space_info->max_extent_size &&
7467 		    num_bytes > space_info->max_extent_size) {
7468 			ins->offset = space_info->max_extent_size;
7469 			spin_unlock(&space_info->lock);
7470 			return -ENOSPC;
7471 		} else if (space_info->max_extent_size) {
7472 			use_cluster = false;
7473 		}
7474 		spin_unlock(&space_info->lock);
7475 	}
7476 
7477 	last_ptr = fetch_cluster_info(fs_info, space_info, &empty_cluster);
7478 	if (last_ptr) {
7479 		spin_lock(&last_ptr->lock);
7480 		if (last_ptr->block_group)
7481 			hint_byte = last_ptr->window_start;
7482 		if (last_ptr->fragmented) {
7483 			/*
7484 			 * We still set window_start so we can keep track of the
7485 			 * last place we found an allocation to try and save
7486 			 * some time.
7487 			 */
7488 			hint_byte = last_ptr->window_start;
7489 			use_cluster = false;
7490 		}
7491 		spin_unlock(&last_ptr->lock);
7492 	}
7493 
7494 	search_start = max(search_start, first_logical_byte(fs_info, 0));
7495 	search_start = max(search_start, hint_byte);
7496 	if (search_start == hint_byte) {
7497 		block_group = btrfs_lookup_block_group(fs_info, search_start);
7498 		/*
7499 		 * we don't want to use the block group if it doesn't match our
7500 		 * allocation bits, or if its not cached.
7501 		 *
7502 		 * However if we are re-searching with an ideal block group
7503 		 * picked out then we don't care that the block group is cached.
7504 		 */
7505 		if (block_group && block_group_bits(block_group, flags) &&
7506 		    block_group->cached != BTRFS_CACHE_NO) {
7507 			down_read(&space_info->groups_sem);
7508 			if (list_empty(&block_group->list) ||
7509 			    block_group->ro) {
7510 				/*
7511 				 * someone is removing this block group,
7512 				 * we can't jump into the have_block_group
7513 				 * target because our list pointers are not
7514 				 * valid
7515 				 */
7516 				btrfs_put_block_group(block_group);
7517 				up_read(&space_info->groups_sem);
7518 			} else {
7519 				index = get_block_group_index(block_group);
7520 				btrfs_lock_block_group(block_group, delalloc);
7521 				goto have_block_group;
7522 			}
7523 		} else if (block_group) {
7524 			btrfs_put_block_group(block_group);
7525 		}
7526 	}
7527 search:
7528 	have_caching_bg = false;
7529 	if (index == 0 || index == __get_raid_index(flags))
7530 		full_search = true;
7531 	down_read(&space_info->groups_sem);
7532 	list_for_each_entry(block_group, &space_info->block_groups[index],
7533 			    list) {
7534 		u64 offset;
7535 		int cached;
7536 
7537 		btrfs_grab_block_group(block_group, delalloc);
7538 		search_start = block_group->key.objectid;
7539 
7540 		/*
7541 		 * this can happen if we end up cycling through all the
7542 		 * raid types, but we want to make sure we only allocate
7543 		 * for the proper type.
7544 		 */
7545 		if (!block_group_bits(block_group, flags)) {
7546 		    u64 extra = BTRFS_BLOCK_GROUP_DUP |
7547 				BTRFS_BLOCK_GROUP_RAID1 |
7548 				BTRFS_BLOCK_GROUP_RAID5 |
7549 				BTRFS_BLOCK_GROUP_RAID6 |
7550 				BTRFS_BLOCK_GROUP_RAID10;
7551 
7552 			/*
7553 			 * if they asked for extra copies and this block group
7554 			 * doesn't provide them, bail.  This does allow us to
7555 			 * fill raid0 from raid1.
7556 			 */
7557 			if ((flags & extra) && !(block_group->flags & extra))
7558 				goto loop;
7559 		}
7560 
7561 have_block_group:
7562 		cached = block_group_cache_done(block_group);
7563 		if (unlikely(!cached)) {
7564 			have_caching_bg = true;
7565 			ret = cache_block_group(block_group, 0);
7566 			BUG_ON(ret < 0);
7567 			ret = 0;
7568 		}
7569 
7570 		if (unlikely(block_group->cached == BTRFS_CACHE_ERROR))
7571 			goto loop;
7572 		if (unlikely(block_group->ro))
7573 			goto loop;
7574 
7575 		/*
7576 		 * Ok we want to try and use the cluster allocator, so
7577 		 * lets look there
7578 		 */
7579 		if (last_ptr && use_cluster) {
7580 			struct btrfs_block_group_cache *used_block_group;
7581 			unsigned long aligned_cluster;
7582 			/*
7583 			 * the refill lock keeps out other
7584 			 * people trying to start a new cluster
7585 			 */
7586 			used_block_group = btrfs_lock_cluster(block_group,
7587 							      last_ptr,
7588 							      delalloc);
7589 			if (!used_block_group)
7590 				goto refill_cluster;
7591 
7592 			if (used_block_group != block_group &&
7593 			    (used_block_group->ro ||
7594 			     !block_group_bits(used_block_group, flags)))
7595 				goto release_cluster;
7596 
7597 			offset = btrfs_alloc_from_cluster(used_block_group,
7598 						last_ptr,
7599 						num_bytes,
7600 						used_block_group->key.objectid,
7601 						&max_extent_size);
7602 			if (offset) {
7603 				/* we have a block, we're done */
7604 				spin_unlock(&last_ptr->refill_lock);
7605 				trace_btrfs_reserve_extent_cluster(fs_info,
7606 						used_block_group,
7607 						search_start, num_bytes);
7608 				if (used_block_group != block_group) {
7609 					btrfs_release_block_group(block_group,
7610 								  delalloc);
7611 					block_group = used_block_group;
7612 				}
7613 				goto checks;
7614 			}
7615 
7616 			WARN_ON(last_ptr->block_group != used_block_group);
7617 release_cluster:
7618 			/* If we are on LOOP_NO_EMPTY_SIZE, we can't
7619 			 * set up a new clusters, so lets just skip it
7620 			 * and let the allocator find whatever block
7621 			 * it can find.  If we reach this point, we
7622 			 * will have tried the cluster allocator
7623 			 * plenty of times and not have found
7624 			 * anything, so we are likely way too
7625 			 * fragmented for the clustering stuff to find
7626 			 * anything.
7627 			 *
7628 			 * However, if the cluster is taken from the
7629 			 * current block group, release the cluster
7630 			 * first, so that we stand a better chance of
7631 			 * succeeding in the unclustered
7632 			 * allocation.  */
7633 			if (loop >= LOOP_NO_EMPTY_SIZE &&
7634 			    used_block_group != block_group) {
7635 				spin_unlock(&last_ptr->refill_lock);
7636 				btrfs_release_block_group(used_block_group,
7637 							  delalloc);
7638 				goto unclustered_alloc;
7639 			}
7640 
7641 			/*
7642 			 * this cluster didn't work out, free it and
7643 			 * start over
7644 			 */
7645 			btrfs_return_cluster_to_free_space(NULL, last_ptr);
7646 
7647 			if (used_block_group != block_group)
7648 				btrfs_release_block_group(used_block_group,
7649 							  delalloc);
7650 refill_cluster:
7651 			if (loop >= LOOP_NO_EMPTY_SIZE) {
7652 				spin_unlock(&last_ptr->refill_lock);
7653 				goto unclustered_alloc;
7654 			}
7655 
7656 			aligned_cluster = max_t(unsigned long,
7657 						empty_cluster + empty_size,
7658 					      block_group->full_stripe_len);
7659 
7660 			/* allocate a cluster in this block group */
7661 			ret = btrfs_find_space_cluster(fs_info, block_group,
7662 						       last_ptr, search_start,
7663 						       num_bytes,
7664 						       aligned_cluster);
7665 			if (ret == 0) {
7666 				/*
7667 				 * now pull our allocation out of this
7668 				 * cluster
7669 				 */
7670 				offset = btrfs_alloc_from_cluster(block_group,
7671 							last_ptr,
7672 							num_bytes,
7673 							search_start,
7674 							&max_extent_size);
7675 				if (offset) {
7676 					/* we found one, proceed */
7677 					spin_unlock(&last_ptr->refill_lock);
7678 					trace_btrfs_reserve_extent_cluster(fs_info,
7679 						block_group, search_start,
7680 						num_bytes);
7681 					goto checks;
7682 				}
7683 			} else if (!cached && loop > LOOP_CACHING_NOWAIT
7684 				   && !failed_cluster_refill) {
7685 				spin_unlock(&last_ptr->refill_lock);
7686 
7687 				failed_cluster_refill = true;
7688 				wait_block_group_cache_progress(block_group,
7689 				       num_bytes + empty_cluster + empty_size);
7690 				goto have_block_group;
7691 			}
7692 
7693 			/*
7694 			 * at this point we either didn't find a cluster
7695 			 * or we weren't able to allocate a block from our
7696 			 * cluster.  Free the cluster we've been trying
7697 			 * to use, and go to the next block group
7698 			 */
7699 			btrfs_return_cluster_to_free_space(NULL, last_ptr);
7700 			spin_unlock(&last_ptr->refill_lock);
7701 			goto loop;
7702 		}
7703 
7704 unclustered_alloc:
7705 		/*
7706 		 * We are doing an unclustered alloc, set the fragmented flag so
7707 		 * we don't bother trying to setup a cluster again until we get
7708 		 * more space.
7709 		 */
7710 		if (unlikely(last_ptr)) {
7711 			spin_lock(&last_ptr->lock);
7712 			last_ptr->fragmented = 1;
7713 			spin_unlock(&last_ptr->lock);
7714 		}
7715 		spin_lock(&block_group->free_space_ctl->tree_lock);
7716 		if (cached &&
7717 		    block_group->free_space_ctl->free_space <
7718 		    num_bytes + empty_cluster + empty_size) {
7719 			if (block_group->free_space_ctl->free_space >
7720 			    max_extent_size)
7721 				max_extent_size =
7722 					block_group->free_space_ctl->free_space;
7723 			spin_unlock(&block_group->free_space_ctl->tree_lock);
7724 			goto loop;
7725 		}
7726 		spin_unlock(&block_group->free_space_ctl->tree_lock);
7727 
7728 		offset = btrfs_find_space_for_alloc(block_group, search_start,
7729 						    num_bytes, empty_size,
7730 						    &max_extent_size);
7731 		/*
7732 		 * If we didn't find a chunk, and we haven't failed on this
7733 		 * block group before, and this block group is in the middle of
7734 		 * caching and we are ok with waiting, then go ahead and wait
7735 		 * for progress to be made, and set failed_alloc to true.
7736 		 *
7737 		 * If failed_alloc is true then we've already waited on this
7738 		 * block group once and should move on to the next block group.
7739 		 */
7740 		if (!offset && !failed_alloc && !cached &&
7741 		    loop > LOOP_CACHING_NOWAIT) {
7742 			wait_block_group_cache_progress(block_group,
7743 						num_bytes + empty_size);
7744 			failed_alloc = true;
7745 			goto have_block_group;
7746 		} else if (!offset) {
7747 			goto loop;
7748 		}
7749 checks:
7750 		search_start = ALIGN(offset, fs_info->stripesize);
7751 
7752 		/* move on to the next group */
7753 		if (search_start + num_bytes >
7754 		    block_group->key.objectid + block_group->key.offset) {
7755 			btrfs_add_free_space(block_group, offset, num_bytes);
7756 			goto loop;
7757 		}
7758 
7759 		if (offset < search_start)
7760 			btrfs_add_free_space(block_group, offset,
7761 					     search_start - offset);
7762 		BUG_ON(offset > search_start);
7763 
7764 		ret = btrfs_add_reserved_bytes(block_group, ram_bytes,
7765 				num_bytes, delalloc);
7766 		if (ret == -EAGAIN) {
7767 			btrfs_add_free_space(block_group, offset, num_bytes);
7768 			goto loop;
7769 		}
7770 		btrfs_inc_block_group_reservations(block_group);
7771 
7772 		/* we are all good, lets return */
7773 		ins->objectid = search_start;
7774 		ins->offset = num_bytes;
7775 
7776 		trace_btrfs_reserve_extent(fs_info, block_group,
7777 					   search_start, num_bytes);
7778 		btrfs_release_block_group(block_group, delalloc);
7779 		break;
7780 loop:
7781 		failed_cluster_refill = false;
7782 		failed_alloc = false;
7783 		BUG_ON(index != get_block_group_index(block_group));
7784 		btrfs_release_block_group(block_group, delalloc);
7785 	}
7786 	up_read(&space_info->groups_sem);
7787 
7788 	if ((loop == LOOP_CACHING_NOWAIT) && have_caching_bg
7789 		&& !orig_have_caching_bg)
7790 		orig_have_caching_bg = true;
7791 
7792 	if (!ins->objectid && loop >= LOOP_CACHING_WAIT && have_caching_bg)
7793 		goto search;
7794 
7795 	if (!ins->objectid && ++index < BTRFS_NR_RAID_TYPES)
7796 		goto search;
7797 
7798 	/*
7799 	 * LOOP_CACHING_NOWAIT, search partially cached block groups, kicking
7800 	 *			caching kthreads as we move along
7801 	 * LOOP_CACHING_WAIT, search everything, and wait if our bg is caching
7802 	 * LOOP_ALLOC_CHUNK, force a chunk allocation and try again
7803 	 * LOOP_NO_EMPTY_SIZE, set empty_size and empty_cluster to 0 and try
7804 	 *			again
7805 	 */
7806 	if (!ins->objectid && loop < LOOP_NO_EMPTY_SIZE) {
7807 		index = 0;
7808 		if (loop == LOOP_CACHING_NOWAIT) {
7809 			/*
7810 			 * We want to skip the LOOP_CACHING_WAIT step if we
7811 			 * don't have any uncached bgs and we've already done a
7812 			 * full search through.
7813 			 */
7814 			if (orig_have_caching_bg || !full_search)
7815 				loop = LOOP_CACHING_WAIT;
7816 			else
7817 				loop = LOOP_ALLOC_CHUNK;
7818 		} else {
7819 			loop++;
7820 		}
7821 
7822 		if (loop == LOOP_ALLOC_CHUNK) {
7823 			struct btrfs_trans_handle *trans;
7824 			int exist = 0;
7825 
7826 			trans = current->journal_info;
7827 			if (trans)
7828 				exist = 1;
7829 			else
7830 				trans = btrfs_join_transaction(root);
7831 
7832 			if (IS_ERR(trans)) {
7833 				ret = PTR_ERR(trans);
7834 				goto out;
7835 			}
7836 
7837 			ret = do_chunk_alloc(trans, fs_info, flags,
7838 					     CHUNK_ALLOC_FORCE);
7839 
7840 			/*
7841 			 * If we can't allocate a new chunk we've already looped
7842 			 * through at least once, move on to the NO_EMPTY_SIZE
7843 			 * case.
7844 			 */
7845 			if (ret == -ENOSPC)
7846 				loop = LOOP_NO_EMPTY_SIZE;
7847 
7848 			/*
7849 			 * Do not bail out on ENOSPC since we
7850 			 * can do more things.
7851 			 */
7852 			if (ret < 0 && ret != -ENOSPC)
7853 				btrfs_abort_transaction(trans, ret);
7854 			else
7855 				ret = 0;
7856 			if (!exist)
7857 				btrfs_end_transaction(trans);
7858 			if (ret)
7859 				goto out;
7860 		}
7861 
7862 		if (loop == LOOP_NO_EMPTY_SIZE) {
7863 			/*
7864 			 * Don't loop again if we already have no empty_size and
7865 			 * no empty_cluster.
7866 			 */
7867 			if (empty_size == 0 &&
7868 			    empty_cluster == 0) {
7869 				ret = -ENOSPC;
7870 				goto out;
7871 			}
7872 			empty_size = 0;
7873 			empty_cluster = 0;
7874 		}
7875 
7876 		goto search;
7877 	} else if (!ins->objectid) {
7878 		ret = -ENOSPC;
7879 	} else if (ins->objectid) {
7880 		if (!use_cluster && last_ptr) {
7881 			spin_lock(&last_ptr->lock);
7882 			last_ptr->window_start = ins->objectid;
7883 			spin_unlock(&last_ptr->lock);
7884 		}
7885 		ret = 0;
7886 	}
7887 out:
7888 	if (ret == -ENOSPC) {
7889 		spin_lock(&space_info->lock);
7890 		space_info->max_extent_size = max_extent_size;
7891 		spin_unlock(&space_info->lock);
7892 		ins->offset = max_extent_size;
7893 	}
7894 	return ret;
7895 }
7896 
7897 static void dump_space_info(struct btrfs_fs_info *fs_info,
7898 			    struct btrfs_space_info *info, u64 bytes,
7899 			    int dump_block_groups)
7900 {
7901 	struct btrfs_block_group_cache *cache;
7902 	int index = 0;
7903 
7904 	spin_lock(&info->lock);
7905 	btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
7906 		   info->flags,
7907 		   info->total_bytes - info->bytes_used - info->bytes_pinned -
7908 		   info->bytes_reserved - info->bytes_readonly -
7909 		   info->bytes_may_use, (info->full) ? "" : "not ");
7910 	btrfs_info(fs_info,
7911 		"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu",
7912 		info->total_bytes, info->bytes_used, info->bytes_pinned,
7913 		info->bytes_reserved, info->bytes_may_use,
7914 		info->bytes_readonly);
7915 	spin_unlock(&info->lock);
7916 
7917 	if (!dump_block_groups)
7918 		return;
7919 
7920 	down_read(&info->groups_sem);
7921 again:
7922 	list_for_each_entry(cache, &info->block_groups[index], list) {
7923 		spin_lock(&cache->lock);
7924 		btrfs_info(fs_info,
7925 			"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %s",
7926 			cache->key.objectid, cache->key.offset,
7927 			btrfs_block_group_used(&cache->item), cache->pinned,
7928 			cache->reserved, cache->ro ? "[readonly]" : "");
7929 		btrfs_dump_free_space(cache, bytes);
7930 		spin_unlock(&cache->lock);
7931 	}
7932 	if (++index < BTRFS_NR_RAID_TYPES)
7933 		goto again;
7934 	up_read(&info->groups_sem);
7935 }
7936 
7937 int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes,
7938 			 u64 num_bytes, u64 min_alloc_size,
7939 			 u64 empty_size, u64 hint_byte,
7940 			 struct btrfs_key *ins, int is_data, int delalloc)
7941 {
7942 	struct btrfs_fs_info *fs_info = root->fs_info;
7943 	bool final_tried = num_bytes == min_alloc_size;
7944 	u64 flags;
7945 	int ret;
7946 
7947 	flags = btrfs_get_alloc_profile(root, is_data);
7948 again:
7949 	WARN_ON(num_bytes < fs_info->sectorsize);
7950 	ret = find_free_extent(root, ram_bytes, num_bytes, empty_size,
7951 			       hint_byte, ins, flags, delalloc);
7952 	if (!ret && !is_data) {
7953 		btrfs_dec_block_group_reservations(fs_info, ins->objectid);
7954 	} else if (ret == -ENOSPC) {
7955 		if (!final_tried && ins->offset) {
7956 			num_bytes = min(num_bytes >> 1, ins->offset);
7957 			num_bytes = round_down(num_bytes,
7958 					       fs_info->sectorsize);
7959 			num_bytes = max(num_bytes, min_alloc_size);
7960 			ram_bytes = num_bytes;
7961 			if (num_bytes == min_alloc_size)
7962 				final_tried = true;
7963 			goto again;
7964 		} else if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
7965 			struct btrfs_space_info *sinfo;
7966 
7967 			sinfo = __find_space_info(fs_info, flags);
7968 			btrfs_err(fs_info,
7969 				  "allocation failed flags %llu, wanted %llu",
7970 				  flags, num_bytes);
7971 			if (sinfo)
7972 				dump_space_info(fs_info, sinfo, num_bytes, 1);
7973 		}
7974 	}
7975 
7976 	return ret;
7977 }
7978 
7979 static int __btrfs_free_reserved_extent(struct btrfs_fs_info *fs_info,
7980 					u64 start, u64 len,
7981 					int pin, int delalloc)
7982 {
7983 	struct btrfs_block_group_cache *cache;
7984 	int ret = 0;
7985 
7986 	cache = btrfs_lookup_block_group(fs_info, start);
7987 	if (!cache) {
7988 		btrfs_err(fs_info, "Unable to find block group for %llu",
7989 			  start);
7990 		return -ENOSPC;
7991 	}
7992 
7993 	if (pin)
7994 		pin_down_extent(fs_info, cache, start, len, 1);
7995 	else {
7996 		if (btrfs_test_opt(fs_info, DISCARD))
7997 			ret = btrfs_discard_extent(fs_info, start, len, NULL);
7998 		btrfs_add_free_space(cache, start, len);
7999 		btrfs_free_reserved_bytes(cache, len, delalloc);
8000 		trace_btrfs_reserved_extent_free(fs_info, start, len);
8001 	}
8002 
8003 	btrfs_put_block_group(cache);
8004 	return ret;
8005 }
8006 
8007 int btrfs_free_reserved_extent(struct btrfs_fs_info *fs_info,
8008 			       u64 start, u64 len, int delalloc)
8009 {
8010 	return __btrfs_free_reserved_extent(fs_info, start, len, 0, delalloc);
8011 }
8012 
8013 int btrfs_free_and_pin_reserved_extent(struct btrfs_fs_info *fs_info,
8014 				       u64 start, u64 len)
8015 {
8016 	return __btrfs_free_reserved_extent(fs_info, start, len, 1, 0);
8017 }
8018 
8019 static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
8020 				      struct btrfs_fs_info *fs_info,
8021 				      u64 parent, u64 root_objectid,
8022 				      u64 flags, u64 owner, u64 offset,
8023 				      struct btrfs_key *ins, int ref_mod)
8024 {
8025 	int ret;
8026 	struct btrfs_extent_item *extent_item;
8027 	struct btrfs_extent_inline_ref *iref;
8028 	struct btrfs_path *path;
8029 	struct extent_buffer *leaf;
8030 	int type;
8031 	u32 size;
8032 
8033 	if (parent > 0)
8034 		type = BTRFS_SHARED_DATA_REF_KEY;
8035 	else
8036 		type = BTRFS_EXTENT_DATA_REF_KEY;
8037 
8038 	size = sizeof(*extent_item) + btrfs_extent_inline_ref_size(type);
8039 
8040 	path = btrfs_alloc_path();
8041 	if (!path)
8042 		return -ENOMEM;
8043 
8044 	path->leave_spinning = 1;
8045 	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
8046 				      ins, size);
8047 	if (ret) {
8048 		btrfs_free_path(path);
8049 		return ret;
8050 	}
8051 
8052 	leaf = path->nodes[0];
8053 	extent_item = btrfs_item_ptr(leaf, path->slots[0],
8054 				     struct btrfs_extent_item);
8055 	btrfs_set_extent_refs(leaf, extent_item, ref_mod);
8056 	btrfs_set_extent_generation(leaf, extent_item, trans->transid);
8057 	btrfs_set_extent_flags(leaf, extent_item,
8058 			       flags | BTRFS_EXTENT_FLAG_DATA);
8059 
8060 	iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
8061 	btrfs_set_extent_inline_ref_type(leaf, iref, type);
8062 	if (parent > 0) {
8063 		struct btrfs_shared_data_ref *ref;
8064 		ref = (struct btrfs_shared_data_ref *)(iref + 1);
8065 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
8066 		btrfs_set_shared_data_ref_count(leaf, ref, ref_mod);
8067 	} else {
8068 		struct btrfs_extent_data_ref *ref;
8069 		ref = (struct btrfs_extent_data_ref *)(&iref->offset);
8070 		btrfs_set_extent_data_ref_root(leaf, ref, root_objectid);
8071 		btrfs_set_extent_data_ref_objectid(leaf, ref, owner);
8072 		btrfs_set_extent_data_ref_offset(leaf, ref, offset);
8073 		btrfs_set_extent_data_ref_count(leaf, ref, ref_mod);
8074 	}
8075 
8076 	btrfs_mark_buffer_dirty(path->nodes[0]);
8077 	btrfs_free_path(path);
8078 
8079 	ret = remove_from_free_space_tree(trans, fs_info, ins->objectid,
8080 					  ins->offset);
8081 	if (ret)
8082 		return ret;
8083 
8084 	ret = update_block_group(trans, fs_info, ins->objectid, ins->offset, 1);
8085 	if (ret) { /* -ENOENT, logic error */
8086 		btrfs_err(fs_info, "update block group failed for %llu %llu",
8087 			ins->objectid, ins->offset);
8088 		BUG();
8089 	}
8090 	trace_btrfs_reserved_extent_alloc(fs_info, ins->objectid, ins->offset);
8091 	return ret;
8092 }
8093 
8094 static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
8095 				     struct btrfs_fs_info *fs_info,
8096 				     u64 parent, u64 root_objectid,
8097 				     u64 flags, struct btrfs_disk_key *key,
8098 				     int level, struct btrfs_key *ins)
8099 {
8100 	int ret;
8101 	struct btrfs_extent_item *extent_item;
8102 	struct btrfs_tree_block_info *block_info;
8103 	struct btrfs_extent_inline_ref *iref;
8104 	struct btrfs_path *path;
8105 	struct extent_buffer *leaf;
8106 	u32 size = sizeof(*extent_item) + sizeof(*iref);
8107 	u64 num_bytes = ins->offset;
8108 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
8109 
8110 	if (!skinny_metadata)
8111 		size += sizeof(*block_info);
8112 
8113 	path = btrfs_alloc_path();
8114 	if (!path) {
8115 		btrfs_free_and_pin_reserved_extent(fs_info, ins->objectid,
8116 						   fs_info->nodesize);
8117 		return -ENOMEM;
8118 	}
8119 
8120 	path->leave_spinning = 1;
8121 	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
8122 				      ins, size);
8123 	if (ret) {
8124 		btrfs_free_path(path);
8125 		btrfs_free_and_pin_reserved_extent(fs_info, ins->objectid,
8126 						   fs_info->nodesize);
8127 		return ret;
8128 	}
8129 
8130 	leaf = path->nodes[0];
8131 	extent_item = btrfs_item_ptr(leaf, path->slots[0],
8132 				     struct btrfs_extent_item);
8133 	btrfs_set_extent_refs(leaf, extent_item, 1);
8134 	btrfs_set_extent_generation(leaf, extent_item, trans->transid);
8135 	btrfs_set_extent_flags(leaf, extent_item,
8136 			       flags | BTRFS_EXTENT_FLAG_TREE_BLOCK);
8137 
8138 	if (skinny_metadata) {
8139 		iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
8140 		num_bytes = fs_info->nodesize;
8141 	} else {
8142 		block_info = (struct btrfs_tree_block_info *)(extent_item + 1);
8143 		btrfs_set_tree_block_key(leaf, block_info, key);
8144 		btrfs_set_tree_block_level(leaf, block_info, level);
8145 		iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
8146 	}
8147 
8148 	if (parent > 0) {
8149 		BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
8150 		btrfs_set_extent_inline_ref_type(leaf, iref,
8151 						 BTRFS_SHARED_BLOCK_REF_KEY);
8152 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
8153 	} else {
8154 		btrfs_set_extent_inline_ref_type(leaf, iref,
8155 						 BTRFS_TREE_BLOCK_REF_KEY);
8156 		btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
8157 	}
8158 
8159 	btrfs_mark_buffer_dirty(leaf);
8160 	btrfs_free_path(path);
8161 
8162 	ret = remove_from_free_space_tree(trans, fs_info, ins->objectid,
8163 					  num_bytes);
8164 	if (ret)
8165 		return ret;
8166 
8167 	ret = update_block_group(trans, fs_info, ins->objectid,
8168 				 fs_info->nodesize, 1);
8169 	if (ret) { /* -ENOENT, logic error */
8170 		btrfs_err(fs_info, "update block group failed for %llu %llu",
8171 			ins->objectid, ins->offset);
8172 		BUG();
8173 	}
8174 
8175 	trace_btrfs_reserved_extent_alloc(fs_info, ins->objectid,
8176 					  fs_info->nodesize);
8177 	return ret;
8178 }
8179 
8180 int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
8181 				     u64 root_objectid, u64 owner,
8182 				     u64 offset, u64 ram_bytes,
8183 				     struct btrfs_key *ins)
8184 {
8185 	struct btrfs_fs_info *fs_info = trans->fs_info;
8186 	int ret;
8187 
8188 	BUG_ON(root_objectid == BTRFS_TREE_LOG_OBJECTID);
8189 
8190 	ret = btrfs_add_delayed_data_ref(fs_info, trans, ins->objectid,
8191 					 ins->offset, 0,
8192 					 root_objectid, owner, offset,
8193 					 ram_bytes, BTRFS_ADD_DELAYED_EXTENT,
8194 					 NULL);
8195 	return ret;
8196 }
8197 
8198 /*
8199  * this is used by the tree logging recovery code.  It records that
8200  * an extent has been allocated and makes sure to clear the free
8201  * space cache bits as well
8202  */
8203 int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
8204 				   struct btrfs_fs_info *fs_info,
8205 				   u64 root_objectid, u64 owner, u64 offset,
8206 				   struct btrfs_key *ins)
8207 {
8208 	int ret;
8209 	struct btrfs_block_group_cache *block_group;
8210 	struct btrfs_space_info *space_info;
8211 
8212 	/*
8213 	 * Mixed block groups will exclude before processing the log so we only
8214 	 * need to do the exclude dance if this fs isn't mixed.
8215 	 */
8216 	if (!btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
8217 		ret = __exclude_logged_extent(fs_info, ins->objectid,
8218 					      ins->offset);
8219 		if (ret)
8220 			return ret;
8221 	}
8222 
8223 	block_group = btrfs_lookup_block_group(fs_info, ins->objectid);
8224 	if (!block_group)
8225 		return -EINVAL;
8226 
8227 	space_info = block_group->space_info;
8228 	spin_lock(&space_info->lock);
8229 	spin_lock(&block_group->lock);
8230 	space_info->bytes_reserved += ins->offset;
8231 	block_group->reserved += ins->offset;
8232 	spin_unlock(&block_group->lock);
8233 	spin_unlock(&space_info->lock);
8234 
8235 	ret = alloc_reserved_file_extent(trans, fs_info, 0, root_objectid,
8236 					 0, owner, offset, ins, 1);
8237 	btrfs_put_block_group(block_group);
8238 	return ret;
8239 }
8240 
8241 static struct extent_buffer *
8242 btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
8243 		      u64 bytenr, int level)
8244 {
8245 	struct btrfs_fs_info *fs_info = root->fs_info;
8246 	struct extent_buffer *buf;
8247 
8248 	buf = btrfs_find_create_tree_block(fs_info, bytenr);
8249 	if (IS_ERR(buf))
8250 		return buf;
8251 
8252 	btrfs_set_header_generation(buf, trans->transid);
8253 	btrfs_set_buffer_lockdep_class(root->root_key.objectid, buf, level);
8254 	btrfs_tree_lock(buf);
8255 	clean_tree_block(trans, fs_info, buf);
8256 	clear_bit(EXTENT_BUFFER_STALE, &buf->bflags);
8257 
8258 	btrfs_set_lock_blocking(buf);
8259 	set_extent_buffer_uptodate(buf);
8260 
8261 	if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
8262 		buf->log_index = root->log_transid % 2;
8263 		/*
8264 		 * we allow two log transactions at a time, use different
8265 		 * EXENT bit to differentiate dirty pages.
8266 		 */
8267 		if (buf->log_index == 0)
8268 			set_extent_dirty(&root->dirty_log_pages, buf->start,
8269 					buf->start + buf->len - 1, GFP_NOFS);
8270 		else
8271 			set_extent_new(&root->dirty_log_pages, buf->start,
8272 					buf->start + buf->len - 1);
8273 	} else {
8274 		buf->log_index = -1;
8275 		set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
8276 			 buf->start + buf->len - 1, GFP_NOFS);
8277 	}
8278 	trans->dirty = true;
8279 	/* this returns a buffer locked for blocking */
8280 	return buf;
8281 }
8282 
8283 static struct btrfs_block_rsv *
8284 use_block_rsv(struct btrfs_trans_handle *trans,
8285 	      struct btrfs_root *root, u32 blocksize)
8286 {
8287 	struct btrfs_fs_info *fs_info = root->fs_info;
8288 	struct btrfs_block_rsv *block_rsv;
8289 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
8290 	int ret;
8291 	bool global_updated = false;
8292 
8293 	block_rsv = get_block_rsv(trans, root);
8294 
8295 	if (unlikely(block_rsv->size == 0))
8296 		goto try_reserve;
8297 again:
8298 	ret = block_rsv_use_bytes(block_rsv, blocksize);
8299 	if (!ret)
8300 		return block_rsv;
8301 
8302 	if (block_rsv->failfast)
8303 		return ERR_PTR(ret);
8304 
8305 	if (block_rsv->type == BTRFS_BLOCK_RSV_GLOBAL && !global_updated) {
8306 		global_updated = true;
8307 		update_global_block_rsv(fs_info);
8308 		goto again;
8309 	}
8310 
8311 	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
8312 		static DEFINE_RATELIMIT_STATE(_rs,
8313 				DEFAULT_RATELIMIT_INTERVAL * 10,
8314 				/*DEFAULT_RATELIMIT_BURST*/ 1);
8315 		if (__ratelimit(&_rs))
8316 			WARN(1, KERN_DEBUG
8317 				"BTRFS: block rsv returned %d\n", ret);
8318 	}
8319 try_reserve:
8320 	ret = reserve_metadata_bytes(root, block_rsv, blocksize,
8321 				     BTRFS_RESERVE_NO_FLUSH);
8322 	if (!ret)
8323 		return block_rsv;
8324 	/*
8325 	 * If we couldn't reserve metadata bytes try and use some from
8326 	 * the global reserve if its space type is the same as the global
8327 	 * reservation.
8328 	 */
8329 	if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL &&
8330 	    block_rsv->space_info == global_rsv->space_info) {
8331 		ret = block_rsv_use_bytes(global_rsv, blocksize);
8332 		if (!ret)
8333 			return global_rsv;
8334 	}
8335 	return ERR_PTR(ret);
8336 }
8337 
8338 static void unuse_block_rsv(struct btrfs_fs_info *fs_info,
8339 			    struct btrfs_block_rsv *block_rsv, u32 blocksize)
8340 {
8341 	block_rsv_add_bytes(block_rsv, blocksize, 0);
8342 	block_rsv_release_bytes(fs_info, block_rsv, NULL, 0);
8343 }
8344 
8345 /*
8346  * finds a free extent and does all the dirty work required for allocation
8347  * returns the tree buffer or an ERR_PTR on error.
8348  */
8349 struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
8350 					struct btrfs_root *root,
8351 					u64 parent, u64 root_objectid,
8352 					struct btrfs_disk_key *key, int level,
8353 					u64 hint, u64 empty_size)
8354 {
8355 	struct btrfs_fs_info *fs_info = root->fs_info;
8356 	struct btrfs_key ins;
8357 	struct btrfs_block_rsv *block_rsv;
8358 	struct extent_buffer *buf;
8359 	struct btrfs_delayed_extent_op *extent_op;
8360 	u64 flags = 0;
8361 	int ret;
8362 	u32 blocksize = fs_info->nodesize;
8363 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
8364 
8365 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
8366 	if (btrfs_is_testing(fs_info)) {
8367 		buf = btrfs_init_new_buffer(trans, root, root->alloc_bytenr,
8368 					    level);
8369 		if (!IS_ERR(buf))
8370 			root->alloc_bytenr += blocksize;
8371 		return buf;
8372 	}
8373 #endif
8374 
8375 	block_rsv = use_block_rsv(trans, root, blocksize);
8376 	if (IS_ERR(block_rsv))
8377 		return ERR_CAST(block_rsv);
8378 
8379 	ret = btrfs_reserve_extent(root, blocksize, blocksize, blocksize,
8380 				   empty_size, hint, &ins, 0, 0);
8381 	if (ret)
8382 		goto out_unuse;
8383 
8384 	buf = btrfs_init_new_buffer(trans, root, ins.objectid, level);
8385 	if (IS_ERR(buf)) {
8386 		ret = PTR_ERR(buf);
8387 		goto out_free_reserved;
8388 	}
8389 
8390 	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
8391 		if (parent == 0)
8392 			parent = ins.objectid;
8393 		flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
8394 	} else
8395 		BUG_ON(parent > 0);
8396 
8397 	if (root_objectid != BTRFS_TREE_LOG_OBJECTID) {
8398 		extent_op = btrfs_alloc_delayed_extent_op();
8399 		if (!extent_op) {
8400 			ret = -ENOMEM;
8401 			goto out_free_buf;
8402 		}
8403 		if (key)
8404 			memcpy(&extent_op->key, key, sizeof(extent_op->key));
8405 		else
8406 			memset(&extent_op->key, 0, sizeof(extent_op->key));
8407 		extent_op->flags_to_set = flags;
8408 		extent_op->update_key = skinny_metadata ? false : true;
8409 		extent_op->update_flags = true;
8410 		extent_op->is_data = false;
8411 		extent_op->level = level;
8412 
8413 		ret = btrfs_add_delayed_tree_ref(fs_info, trans,
8414 						 ins.objectid, ins.offset,
8415 						 parent, root_objectid, level,
8416 						 BTRFS_ADD_DELAYED_EXTENT,
8417 						 extent_op);
8418 		if (ret)
8419 			goto out_free_delayed;
8420 	}
8421 	return buf;
8422 
8423 out_free_delayed:
8424 	btrfs_free_delayed_extent_op(extent_op);
8425 out_free_buf:
8426 	free_extent_buffer(buf);
8427 out_free_reserved:
8428 	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 0);
8429 out_unuse:
8430 	unuse_block_rsv(fs_info, block_rsv, blocksize);
8431 	return ERR_PTR(ret);
8432 }
8433 
8434 struct walk_control {
8435 	u64 refs[BTRFS_MAX_LEVEL];
8436 	u64 flags[BTRFS_MAX_LEVEL];
8437 	struct btrfs_key update_progress;
8438 	int stage;
8439 	int level;
8440 	int shared_level;
8441 	int update_ref;
8442 	int keep_locks;
8443 	int reada_slot;
8444 	int reada_count;
8445 	int for_reloc;
8446 };
8447 
8448 #define DROP_REFERENCE	1
8449 #define UPDATE_BACKREF	2
8450 
8451 static noinline void reada_walk_down(struct btrfs_trans_handle *trans,
8452 				     struct btrfs_root *root,
8453 				     struct walk_control *wc,
8454 				     struct btrfs_path *path)
8455 {
8456 	struct btrfs_fs_info *fs_info = root->fs_info;
8457 	u64 bytenr;
8458 	u64 generation;
8459 	u64 refs;
8460 	u64 flags;
8461 	u32 nritems;
8462 	struct btrfs_key key;
8463 	struct extent_buffer *eb;
8464 	int ret;
8465 	int slot;
8466 	int nread = 0;
8467 
8468 	if (path->slots[wc->level] < wc->reada_slot) {
8469 		wc->reada_count = wc->reada_count * 2 / 3;
8470 		wc->reada_count = max(wc->reada_count, 2);
8471 	} else {
8472 		wc->reada_count = wc->reada_count * 3 / 2;
8473 		wc->reada_count = min_t(int, wc->reada_count,
8474 					BTRFS_NODEPTRS_PER_BLOCK(fs_info));
8475 	}
8476 
8477 	eb = path->nodes[wc->level];
8478 	nritems = btrfs_header_nritems(eb);
8479 
8480 	for (slot = path->slots[wc->level]; slot < nritems; slot++) {
8481 		if (nread >= wc->reada_count)
8482 			break;
8483 
8484 		cond_resched();
8485 		bytenr = btrfs_node_blockptr(eb, slot);
8486 		generation = btrfs_node_ptr_generation(eb, slot);
8487 
8488 		if (slot == path->slots[wc->level])
8489 			goto reada;
8490 
8491 		if (wc->stage == UPDATE_BACKREF &&
8492 		    generation <= root->root_key.offset)
8493 			continue;
8494 
8495 		/* We don't lock the tree block, it's OK to be racy here */
8496 		ret = btrfs_lookup_extent_info(trans, fs_info, bytenr,
8497 					       wc->level - 1, 1, &refs,
8498 					       &flags);
8499 		/* We don't care about errors in readahead. */
8500 		if (ret < 0)
8501 			continue;
8502 		BUG_ON(refs == 0);
8503 
8504 		if (wc->stage == DROP_REFERENCE) {
8505 			if (refs == 1)
8506 				goto reada;
8507 
8508 			if (wc->level == 1 &&
8509 			    (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
8510 				continue;
8511 			if (!wc->update_ref ||
8512 			    generation <= root->root_key.offset)
8513 				continue;
8514 			btrfs_node_key_to_cpu(eb, &key, slot);
8515 			ret = btrfs_comp_cpu_keys(&key,
8516 						  &wc->update_progress);
8517 			if (ret < 0)
8518 				continue;
8519 		} else {
8520 			if (wc->level == 1 &&
8521 			    (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
8522 				continue;
8523 		}
8524 reada:
8525 		readahead_tree_block(fs_info, bytenr);
8526 		nread++;
8527 	}
8528 	wc->reada_slot = slot;
8529 }
8530 
8531 /*
8532  * helper to process tree block while walking down the tree.
8533  *
8534  * when wc->stage == UPDATE_BACKREF, this function updates
8535  * back refs for pointers in the block.
8536  *
8537  * NOTE: return value 1 means we should stop walking down.
8538  */
8539 static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
8540 				   struct btrfs_root *root,
8541 				   struct btrfs_path *path,
8542 				   struct walk_control *wc, int lookup_info)
8543 {
8544 	struct btrfs_fs_info *fs_info = root->fs_info;
8545 	int level = wc->level;
8546 	struct extent_buffer *eb = path->nodes[level];
8547 	u64 flag = BTRFS_BLOCK_FLAG_FULL_BACKREF;
8548 	int ret;
8549 
8550 	if (wc->stage == UPDATE_BACKREF &&
8551 	    btrfs_header_owner(eb) != root->root_key.objectid)
8552 		return 1;
8553 
8554 	/*
8555 	 * when reference count of tree block is 1, it won't increase
8556 	 * again. once full backref flag is set, we never clear it.
8557 	 */
8558 	if (lookup_info &&
8559 	    ((wc->stage == DROP_REFERENCE && wc->refs[level] != 1) ||
8560 	     (wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag)))) {
8561 		BUG_ON(!path->locks[level]);
8562 		ret = btrfs_lookup_extent_info(trans, fs_info,
8563 					       eb->start, level, 1,
8564 					       &wc->refs[level],
8565 					       &wc->flags[level]);
8566 		BUG_ON(ret == -ENOMEM);
8567 		if (ret)
8568 			return ret;
8569 		BUG_ON(wc->refs[level] == 0);
8570 	}
8571 
8572 	if (wc->stage == DROP_REFERENCE) {
8573 		if (wc->refs[level] > 1)
8574 			return 1;
8575 
8576 		if (path->locks[level] && !wc->keep_locks) {
8577 			btrfs_tree_unlock_rw(eb, path->locks[level]);
8578 			path->locks[level] = 0;
8579 		}
8580 		return 0;
8581 	}
8582 
8583 	/* wc->stage == UPDATE_BACKREF */
8584 	if (!(wc->flags[level] & flag)) {
8585 		BUG_ON(!path->locks[level]);
8586 		ret = btrfs_inc_ref(trans, root, eb, 1);
8587 		BUG_ON(ret); /* -ENOMEM */
8588 		ret = btrfs_dec_ref(trans, root, eb, 0);
8589 		BUG_ON(ret); /* -ENOMEM */
8590 		ret = btrfs_set_disk_extent_flags(trans, fs_info, eb->start,
8591 						  eb->len, flag,
8592 						  btrfs_header_level(eb), 0);
8593 		BUG_ON(ret); /* -ENOMEM */
8594 		wc->flags[level] |= flag;
8595 	}
8596 
8597 	/*
8598 	 * the block is shared by multiple trees, so it's not good to
8599 	 * keep the tree lock
8600 	 */
8601 	if (path->locks[level] && level > 0) {
8602 		btrfs_tree_unlock_rw(eb, path->locks[level]);
8603 		path->locks[level] = 0;
8604 	}
8605 	return 0;
8606 }
8607 
8608 /*
8609  * helper to process tree block pointer.
8610  *
8611  * when wc->stage == DROP_REFERENCE, this function checks
8612  * reference count of the block pointed to. if the block
8613  * is shared and we need update back refs for the subtree
8614  * rooted at the block, this function changes wc->stage to
8615  * UPDATE_BACKREF. if the block is shared and there is no
8616  * need to update back, this function drops the reference
8617  * to the block.
8618  *
8619  * NOTE: return value 1 means we should stop walking down.
8620  */
8621 static noinline int do_walk_down(struct btrfs_trans_handle *trans,
8622 				 struct btrfs_root *root,
8623 				 struct btrfs_path *path,
8624 				 struct walk_control *wc, int *lookup_info)
8625 {
8626 	struct btrfs_fs_info *fs_info = root->fs_info;
8627 	u64 bytenr;
8628 	u64 generation;
8629 	u64 parent;
8630 	u32 blocksize;
8631 	struct btrfs_key key;
8632 	struct extent_buffer *next;
8633 	int level = wc->level;
8634 	int reada = 0;
8635 	int ret = 0;
8636 	bool need_account = false;
8637 
8638 	generation = btrfs_node_ptr_generation(path->nodes[level],
8639 					       path->slots[level]);
8640 	/*
8641 	 * if the lower level block was created before the snapshot
8642 	 * was created, we know there is no need to update back refs
8643 	 * for the subtree
8644 	 */
8645 	if (wc->stage == UPDATE_BACKREF &&
8646 	    generation <= root->root_key.offset) {
8647 		*lookup_info = 1;
8648 		return 1;
8649 	}
8650 
8651 	bytenr = btrfs_node_blockptr(path->nodes[level], path->slots[level]);
8652 	blocksize = fs_info->nodesize;
8653 
8654 	next = find_extent_buffer(fs_info, bytenr);
8655 	if (!next) {
8656 		next = btrfs_find_create_tree_block(fs_info, bytenr);
8657 		if (IS_ERR(next))
8658 			return PTR_ERR(next);
8659 
8660 		btrfs_set_buffer_lockdep_class(root->root_key.objectid, next,
8661 					       level - 1);
8662 		reada = 1;
8663 	}
8664 	btrfs_tree_lock(next);
8665 	btrfs_set_lock_blocking(next);
8666 
8667 	ret = btrfs_lookup_extent_info(trans, fs_info, bytenr, level - 1, 1,
8668 				       &wc->refs[level - 1],
8669 				       &wc->flags[level - 1]);
8670 	if (ret < 0)
8671 		goto out_unlock;
8672 
8673 	if (unlikely(wc->refs[level - 1] == 0)) {
8674 		btrfs_err(fs_info, "Missing references.");
8675 		ret = -EIO;
8676 		goto out_unlock;
8677 	}
8678 	*lookup_info = 0;
8679 
8680 	if (wc->stage == DROP_REFERENCE) {
8681 		if (wc->refs[level - 1] > 1) {
8682 			need_account = true;
8683 			if (level == 1 &&
8684 			    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))
8685 				goto skip;
8686 
8687 			if (!wc->update_ref ||
8688 			    generation <= root->root_key.offset)
8689 				goto skip;
8690 
8691 			btrfs_node_key_to_cpu(path->nodes[level], &key,
8692 					      path->slots[level]);
8693 			ret = btrfs_comp_cpu_keys(&key, &wc->update_progress);
8694 			if (ret < 0)
8695 				goto skip;
8696 
8697 			wc->stage = UPDATE_BACKREF;
8698 			wc->shared_level = level - 1;
8699 		}
8700 	} else {
8701 		if (level == 1 &&
8702 		    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))
8703 			goto skip;
8704 	}
8705 
8706 	if (!btrfs_buffer_uptodate(next, generation, 0)) {
8707 		btrfs_tree_unlock(next);
8708 		free_extent_buffer(next);
8709 		next = NULL;
8710 		*lookup_info = 1;
8711 	}
8712 
8713 	if (!next) {
8714 		if (reada && level == 1)
8715 			reada_walk_down(trans, root, wc, path);
8716 		next = read_tree_block(fs_info, bytenr, generation);
8717 		if (IS_ERR(next)) {
8718 			return PTR_ERR(next);
8719 		} else if (!extent_buffer_uptodate(next)) {
8720 			free_extent_buffer(next);
8721 			return -EIO;
8722 		}
8723 		btrfs_tree_lock(next);
8724 		btrfs_set_lock_blocking(next);
8725 	}
8726 
8727 	level--;
8728 	ASSERT(level == btrfs_header_level(next));
8729 	if (level != btrfs_header_level(next)) {
8730 		btrfs_err(root->fs_info, "mismatched level");
8731 		ret = -EIO;
8732 		goto out_unlock;
8733 	}
8734 	path->nodes[level] = next;
8735 	path->slots[level] = 0;
8736 	path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
8737 	wc->level = level;
8738 	if (wc->level == 1)
8739 		wc->reada_slot = 0;
8740 	return 0;
8741 skip:
8742 	wc->refs[level - 1] = 0;
8743 	wc->flags[level - 1] = 0;
8744 	if (wc->stage == DROP_REFERENCE) {
8745 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
8746 			parent = path->nodes[level]->start;
8747 		} else {
8748 			ASSERT(root->root_key.objectid ==
8749 			       btrfs_header_owner(path->nodes[level]));
8750 			if (root->root_key.objectid !=
8751 			    btrfs_header_owner(path->nodes[level])) {
8752 				btrfs_err(root->fs_info,
8753 						"mismatched block owner");
8754 				ret = -EIO;
8755 				goto out_unlock;
8756 			}
8757 			parent = 0;
8758 		}
8759 
8760 		if (need_account) {
8761 			ret = btrfs_qgroup_trace_subtree(trans, root, next,
8762 							 generation, level - 1);
8763 			if (ret) {
8764 				btrfs_err_rl(fs_info,
8765 					     "Error %d accounting shared subtree. Quota is out of sync, rescan required.",
8766 					     ret);
8767 			}
8768 		}
8769 		ret = btrfs_free_extent(trans, fs_info, bytenr, blocksize,
8770 					parent, root->root_key.objectid,
8771 					level - 1, 0);
8772 		if (ret)
8773 			goto out_unlock;
8774 	}
8775 
8776 	*lookup_info = 1;
8777 	ret = 1;
8778 
8779 out_unlock:
8780 	btrfs_tree_unlock(next);
8781 	free_extent_buffer(next);
8782 
8783 	return ret;
8784 }
8785 
8786 /*
8787  * helper to process tree block while walking up the tree.
8788  *
8789  * when wc->stage == DROP_REFERENCE, this function drops
8790  * reference count on the block.
8791  *
8792  * when wc->stage == UPDATE_BACKREF, this function changes
8793  * wc->stage back to DROP_REFERENCE if we changed wc->stage
8794  * to UPDATE_BACKREF previously while processing the block.
8795  *
8796  * NOTE: return value 1 means we should stop walking up.
8797  */
8798 static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
8799 				 struct btrfs_root *root,
8800 				 struct btrfs_path *path,
8801 				 struct walk_control *wc)
8802 {
8803 	struct btrfs_fs_info *fs_info = root->fs_info;
8804 	int ret;
8805 	int level = wc->level;
8806 	struct extent_buffer *eb = path->nodes[level];
8807 	u64 parent = 0;
8808 
8809 	if (wc->stage == UPDATE_BACKREF) {
8810 		BUG_ON(wc->shared_level < level);
8811 		if (level < wc->shared_level)
8812 			goto out;
8813 
8814 		ret = find_next_key(path, level + 1, &wc->update_progress);
8815 		if (ret > 0)
8816 			wc->update_ref = 0;
8817 
8818 		wc->stage = DROP_REFERENCE;
8819 		wc->shared_level = -1;
8820 		path->slots[level] = 0;
8821 
8822 		/*
8823 		 * check reference count again if the block isn't locked.
8824 		 * we should start walking down the tree again if reference
8825 		 * count is one.
8826 		 */
8827 		if (!path->locks[level]) {
8828 			BUG_ON(level == 0);
8829 			btrfs_tree_lock(eb);
8830 			btrfs_set_lock_blocking(eb);
8831 			path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
8832 
8833 			ret = btrfs_lookup_extent_info(trans, fs_info,
8834 						       eb->start, level, 1,
8835 						       &wc->refs[level],
8836 						       &wc->flags[level]);
8837 			if (ret < 0) {
8838 				btrfs_tree_unlock_rw(eb, path->locks[level]);
8839 				path->locks[level] = 0;
8840 				return ret;
8841 			}
8842 			BUG_ON(wc->refs[level] == 0);
8843 			if (wc->refs[level] == 1) {
8844 				btrfs_tree_unlock_rw(eb, path->locks[level]);
8845 				path->locks[level] = 0;
8846 				return 1;
8847 			}
8848 		}
8849 	}
8850 
8851 	/* wc->stage == DROP_REFERENCE */
8852 	BUG_ON(wc->refs[level] > 1 && !path->locks[level]);
8853 
8854 	if (wc->refs[level] == 1) {
8855 		if (level == 0) {
8856 			if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
8857 				ret = btrfs_dec_ref(trans, root, eb, 1);
8858 			else
8859 				ret = btrfs_dec_ref(trans, root, eb, 0);
8860 			BUG_ON(ret); /* -ENOMEM */
8861 			ret = btrfs_qgroup_trace_leaf_items(trans, fs_info, eb);
8862 			if (ret) {
8863 				btrfs_err_rl(fs_info,
8864 					     "error %d accounting leaf items. Quota is out of sync, rescan required.",
8865 					     ret);
8866 			}
8867 		}
8868 		/* make block locked assertion in clean_tree_block happy */
8869 		if (!path->locks[level] &&
8870 		    btrfs_header_generation(eb) == trans->transid) {
8871 			btrfs_tree_lock(eb);
8872 			btrfs_set_lock_blocking(eb);
8873 			path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
8874 		}
8875 		clean_tree_block(trans, fs_info, eb);
8876 	}
8877 
8878 	if (eb == root->node) {
8879 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
8880 			parent = eb->start;
8881 		else
8882 			BUG_ON(root->root_key.objectid !=
8883 			       btrfs_header_owner(eb));
8884 	} else {
8885 		if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
8886 			parent = path->nodes[level + 1]->start;
8887 		else
8888 			BUG_ON(root->root_key.objectid !=
8889 			       btrfs_header_owner(path->nodes[level + 1]));
8890 	}
8891 
8892 	btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1);
8893 out:
8894 	wc->refs[level] = 0;
8895 	wc->flags[level] = 0;
8896 	return 0;
8897 }
8898 
8899 static noinline int walk_down_tree(struct btrfs_trans_handle *trans,
8900 				   struct btrfs_root *root,
8901 				   struct btrfs_path *path,
8902 				   struct walk_control *wc)
8903 {
8904 	int level = wc->level;
8905 	int lookup_info = 1;
8906 	int ret;
8907 
8908 	while (level >= 0) {
8909 		ret = walk_down_proc(trans, root, path, wc, lookup_info);
8910 		if (ret > 0)
8911 			break;
8912 
8913 		if (level == 0)
8914 			break;
8915 
8916 		if (path->slots[level] >=
8917 		    btrfs_header_nritems(path->nodes[level]))
8918 			break;
8919 
8920 		ret = do_walk_down(trans, root, path, wc, &lookup_info);
8921 		if (ret > 0) {
8922 			path->slots[level]++;
8923 			continue;
8924 		} else if (ret < 0)
8925 			return ret;
8926 		level = wc->level;
8927 	}
8928 	return 0;
8929 }
8930 
8931 static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
8932 				 struct btrfs_root *root,
8933 				 struct btrfs_path *path,
8934 				 struct walk_control *wc, int max_level)
8935 {
8936 	int level = wc->level;
8937 	int ret;
8938 
8939 	path->slots[level] = btrfs_header_nritems(path->nodes[level]);
8940 	while (level < max_level && path->nodes[level]) {
8941 		wc->level = level;
8942 		if (path->slots[level] + 1 <
8943 		    btrfs_header_nritems(path->nodes[level])) {
8944 			path->slots[level]++;
8945 			return 0;
8946 		} else {
8947 			ret = walk_up_proc(trans, root, path, wc);
8948 			if (ret > 0)
8949 				return 0;
8950 
8951 			if (path->locks[level]) {
8952 				btrfs_tree_unlock_rw(path->nodes[level],
8953 						     path->locks[level]);
8954 				path->locks[level] = 0;
8955 			}
8956 			free_extent_buffer(path->nodes[level]);
8957 			path->nodes[level] = NULL;
8958 			level++;
8959 		}
8960 	}
8961 	return 1;
8962 }
8963 
8964 /*
8965  * drop a subvolume tree.
8966  *
8967  * this function traverses the tree freeing any blocks that only
8968  * referenced by the tree.
8969  *
8970  * when a shared tree block is found. this function decreases its
8971  * reference count by one. if update_ref is true, this function
8972  * also make sure backrefs for the shared block and all lower level
8973  * blocks are properly updated.
8974  *
8975  * If called with for_reloc == 0, may exit early with -EAGAIN
8976  */
8977 int btrfs_drop_snapshot(struct btrfs_root *root,
8978 			 struct btrfs_block_rsv *block_rsv, int update_ref,
8979 			 int for_reloc)
8980 {
8981 	struct btrfs_fs_info *fs_info = root->fs_info;
8982 	struct btrfs_path *path;
8983 	struct btrfs_trans_handle *trans;
8984 	struct btrfs_root *tree_root = fs_info->tree_root;
8985 	struct btrfs_root_item *root_item = &root->root_item;
8986 	struct walk_control *wc;
8987 	struct btrfs_key key;
8988 	int err = 0;
8989 	int ret;
8990 	int level;
8991 	bool root_dropped = false;
8992 
8993 	btrfs_debug(fs_info, "Drop subvolume %llu", root->objectid);
8994 
8995 	path = btrfs_alloc_path();
8996 	if (!path) {
8997 		err = -ENOMEM;
8998 		goto out;
8999 	}
9000 
9001 	wc = kzalloc(sizeof(*wc), GFP_NOFS);
9002 	if (!wc) {
9003 		btrfs_free_path(path);
9004 		err = -ENOMEM;
9005 		goto out;
9006 	}
9007 
9008 	trans = btrfs_start_transaction(tree_root, 0);
9009 	if (IS_ERR(trans)) {
9010 		err = PTR_ERR(trans);
9011 		goto out_free;
9012 	}
9013 
9014 	if (block_rsv)
9015 		trans->block_rsv = block_rsv;
9016 
9017 	if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
9018 		level = btrfs_header_level(root->node);
9019 		path->nodes[level] = btrfs_lock_root_node(root);
9020 		btrfs_set_lock_blocking(path->nodes[level]);
9021 		path->slots[level] = 0;
9022 		path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
9023 		memset(&wc->update_progress, 0,
9024 		       sizeof(wc->update_progress));
9025 	} else {
9026 		btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
9027 		memcpy(&wc->update_progress, &key,
9028 		       sizeof(wc->update_progress));
9029 
9030 		level = root_item->drop_level;
9031 		BUG_ON(level == 0);
9032 		path->lowest_level = level;
9033 		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
9034 		path->lowest_level = 0;
9035 		if (ret < 0) {
9036 			err = ret;
9037 			goto out_end_trans;
9038 		}
9039 		WARN_ON(ret > 0);
9040 
9041 		/*
9042 		 * unlock our path, this is safe because only this
9043 		 * function is allowed to delete this snapshot
9044 		 */
9045 		btrfs_unlock_up_safe(path, 0);
9046 
9047 		level = btrfs_header_level(root->node);
9048 		while (1) {
9049 			btrfs_tree_lock(path->nodes[level]);
9050 			btrfs_set_lock_blocking(path->nodes[level]);
9051 			path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
9052 
9053 			ret = btrfs_lookup_extent_info(trans, fs_info,
9054 						path->nodes[level]->start,
9055 						level, 1, &wc->refs[level],
9056 						&wc->flags[level]);
9057 			if (ret < 0) {
9058 				err = ret;
9059 				goto out_end_trans;
9060 			}
9061 			BUG_ON(wc->refs[level] == 0);
9062 
9063 			if (level == root_item->drop_level)
9064 				break;
9065 
9066 			btrfs_tree_unlock(path->nodes[level]);
9067 			path->locks[level] = 0;
9068 			WARN_ON(wc->refs[level] != 1);
9069 			level--;
9070 		}
9071 	}
9072 
9073 	wc->level = level;
9074 	wc->shared_level = -1;
9075 	wc->stage = DROP_REFERENCE;
9076 	wc->update_ref = update_ref;
9077 	wc->keep_locks = 0;
9078 	wc->for_reloc = for_reloc;
9079 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);
9080 
9081 	while (1) {
9082 
9083 		ret = walk_down_tree(trans, root, path, wc);
9084 		if (ret < 0) {
9085 			err = ret;
9086 			break;
9087 		}
9088 
9089 		ret = walk_up_tree(trans, root, path, wc, BTRFS_MAX_LEVEL);
9090 		if (ret < 0) {
9091 			err = ret;
9092 			break;
9093 		}
9094 
9095 		if (ret > 0) {
9096 			BUG_ON(wc->stage != DROP_REFERENCE);
9097 			break;
9098 		}
9099 
9100 		if (wc->stage == DROP_REFERENCE) {
9101 			level = wc->level;
9102 			btrfs_node_key(path->nodes[level],
9103 				       &root_item->drop_progress,
9104 				       path->slots[level]);
9105 			root_item->drop_level = level;
9106 		}
9107 
9108 		BUG_ON(wc->level == 0);
9109 		if (btrfs_should_end_transaction(trans) ||
9110 		    (!for_reloc && btrfs_need_cleaner_sleep(fs_info))) {
9111 			ret = btrfs_update_root(trans, tree_root,
9112 						&root->root_key,
9113 						root_item);
9114 			if (ret) {
9115 				btrfs_abort_transaction(trans, ret);
9116 				err = ret;
9117 				goto out_end_trans;
9118 			}
9119 
9120 			btrfs_end_transaction_throttle(trans);
9121 			if (!for_reloc && btrfs_need_cleaner_sleep(fs_info)) {
9122 				btrfs_debug(fs_info,
9123 					    "drop snapshot early exit");
9124 				err = -EAGAIN;
9125 				goto out_free;
9126 			}
9127 
9128 			trans = btrfs_start_transaction(tree_root, 0);
9129 			if (IS_ERR(trans)) {
9130 				err = PTR_ERR(trans);
9131 				goto out_free;
9132 			}
9133 			if (block_rsv)
9134 				trans->block_rsv = block_rsv;
9135 		}
9136 	}
9137 	btrfs_release_path(path);
9138 	if (err)
9139 		goto out_end_trans;
9140 
9141 	ret = btrfs_del_root(trans, tree_root, &root->root_key);
9142 	if (ret) {
9143 		btrfs_abort_transaction(trans, ret);
9144 		goto out_end_trans;
9145 	}
9146 
9147 	if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
9148 		ret = btrfs_find_root(tree_root, &root->root_key, path,
9149 				      NULL, NULL);
9150 		if (ret < 0) {
9151 			btrfs_abort_transaction(trans, ret);
9152 			err = ret;
9153 			goto out_end_trans;
9154 		} else if (ret > 0) {
9155 			/* if we fail to delete the orphan item this time
9156 			 * around, it'll get picked up the next time.
9157 			 *
9158 			 * The most common failure here is just -ENOENT.
9159 			 */
9160 			btrfs_del_orphan_item(trans, tree_root,
9161 					      root->root_key.objectid);
9162 		}
9163 	}
9164 
9165 	if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state)) {
9166 		btrfs_add_dropped_root(trans, root);
9167 	} else {
9168 		free_extent_buffer(root->node);
9169 		free_extent_buffer(root->commit_root);
9170 		btrfs_put_fs_root(root);
9171 	}
9172 	root_dropped = true;
9173 out_end_trans:
9174 	btrfs_end_transaction_throttle(trans);
9175 out_free:
9176 	kfree(wc);
9177 	btrfs_free_path(path);
9178 out:
9179 	/*
9180 	 * So if we need to stop dropping the snapshot for whatever reason we
9181 	 * need to make sure to add it back to the dead root list so that we
9182 	 * keep trying to do the work later.  This also cleans up roots if we
9183 	 * don't have it in the radix (like when we recover after a power fail
9184 	 * or unmount) so we don't leak memory.
9185 	 */
9186 	if (!for_reloc && root_dropped == false)
9187 		btrfs_add_dead_root(root);
9188 	if (err && err != -EAGAIN)
9189 		btrfs_handle_fs_error(fs_info, err, NULL);
9190 	return err;
9191 }
9192 
9193 /*
9194  * drop subtree rooted at tree block 'node'.
9195  *
9196  * NOTE: this function will unlock and release tree block 'node'
9197  * only used by relocation code
9198  */
9199 int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
9200 			struct btrfs_root *root,
9201 			struct extent_buffer *node,
9202 			struct extent_buffer *parent)
9203 {
9204 	struct btrfs_fs_info *fs_info = root->fs_info;
9205 	struct btrfs_path *path;
9206 	struct walk_control *wc;
9207 	int level;
9208 	int parent_level;
9209 	int ret = 0;
9210 	int wret;
9211 
9212 	BUG_ON(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
9213 
9214 	path = btrfs_alloc_path();
9215 	if (!path)
9216 		return -ENOMEM;
9217 
9218 	wc = kzalloc(sizeof(*wc), GFP_NOFS);
9219 	if (!wc) {
9220 		btrfs_free_path(path);
9221 		return -ENOMEM;
9222 	}
9223 
9224 	btrfs_assert_tree_locked(parent);
9225 	parent_level = btrfs_header_level(parent);
9226 	extent_buffer_get(parent);
9227 	path->nodes[parent_level] = parent;
9228 	path->slots[parent_level] = btrfs_header_nritems(parent);
9229 
9230 	btrfs_assert_tree_locked(node);
9231 	level = btrfs_header_level(node);
9232 	path->nodes[level] = node;
9233 	path->slots[level] = 0;
9234 	path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
9235 
9236 	wc->refs[parent_level] = 1;
9237 	wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;
9238 	wc->level = level;
9239 	wc->shared_level = -1;
9240 	wc->stage = DROP_REFERENCE;
9241 	wc->update_ref = 0;
9242 	wc->keep_locks = 1;
9243 	wc->for_reloc = 1;
9244 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);
9245 
9246 	while (1) {
9247 		wret = walk_down_tree(trans, root, path, wc);
9248 		if (wret < 0) {
9249 			ret = wret;
9250 			break;
9251 		}
9252 
9253 		wret = walk_up_tree(trans, root, path, wc, parent_level);
9254 		if (wret < 0)
9255 			ret = wret;
9256 		if (wret != 0)
9257 			break;
9258 	}
9259 
9260 	kfree(wc);
9261 	btrfs_free_path(path);
9262 	return ret;
9263 }
9264 
9265 static u64 update_block_group_flags(struct btrfs_fs_info *fs_info, u64 flags)
9266 {
9267 	u64 num_devices;
9268 	u64 stripped;
9269 
9270 	/*
9271 	 * if restripe for this chunk_type is on pick target profile and
9272 	 * return, otherwise do the usual balance
9273 	 */
9274 	stripped = get_restripe_target(fs_info, flags);
9275 	if (stripped)
9276 		return extended_to_chunk(stripped);
9277 
9278 	num_devices = fs_info->fs_devices->rw_devices;
9279 
9280 	stripped = BTRFS_BLOCK_GROUP_RAID0 |
9281 		BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6 |
9282 		BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10;
9283 
9284 	if (num_devices == 1) {
9285 		stripped |= BTRFS_BLOCK_GROUP_DUP;
9286 		stripped = flags & ~stripped;
9287 
9288 		/* turn raid0 into single device chunks */
9289 		if (flags & BTRFS_BLOCK_GROUP_RAID0)
9290 			return stripped;
9291 
9292 		/* turn mirroring into duplication */
9293 		if (flags & (BTRFS_BLOCK_GROUP_RAID1 |
9294 			     BTRFS_BLOCK_GROUP_RAID10))
9295 			return stripped | BTRFS_BLOCK_GROUP_DUP;
9296 	} else {
9297 		/* they already had raid on here, just return */
9298 		if (flags & stripped)
9299 			return flags;
9300 
9301 		stripped |= BTRFS_BLOCK_GROUP_DUP;
9302 		stripped = flags & ~stripped;
9303 
9304 		/* switch duplicated blocks with raid1 */
9305 		if (flags & BTRFS_BLOCK_GROUP_DUP)
9306 			return stripped | BTRFS_BLOCK_GROUP_RAID1;
9307 
9308 		/* this is drive concat, leave it alone */
9309 	}
9310 
9311 	return flags;
9312 }
9313 
9314 static int inc_block_group_ro(struct btrfs_block_group_cache *cache, int force)
9315 {
9316 	struct btrfs_space_info *sinfo = cache->space_info;
9317 	u64 num_bytes;
9318 	u64 min_allocable_bytes;
9319 	int ret = -ENOSPC;
9320 
9321 	/*
9322 	 * We need some metadata space and system metadata space for
9323 	 * allocating chunks in some corner cases until we force to set
9324 	 * it to be readonly.
9325 	 */
9326 	if ((sinfo->flags &
9327 	     (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_METADATA)) &&
9328 	    !force)
9329 		min_allocable_bytes = SZ_1M;
9330 	else
9331 		min_allocable_bytes = 0;
9332 
9333 	spin_lock(&sinfo->lock);
9334 	spin_lock(&cache->lock);
9335 
9336 	if (cache->ro) {
9337 		cache->ro++;
9338 		ret = 0;
9339 		goto out;
9340 	}
9341 
9342 	num_bytes = cache->key.offset - cache->reserved - cache->pinned -
9343 		    cache->bytes_super - btrfs_block_group_used(&cache->item);
9344 
9345 	if (sinfo->bytes_used + sinfo->bytes_reserved + sinfo->bytes_pinned +
9346 	    sinfo->bytes_may_use + sinfo->bytes_readonly + num_bytes +
9347 	    min_allocable_bytes <= sinfo->total_bytes) {
9348 		sinfo->bytes_readonly += num_bytes;
9349 		cache->ro++;
9350 		list_add_tail(&cache->ro_list, &sinfo->ro_bgs);
9351 		ret = 0;
9352 	}
9353 out:
9354 	spin_unlock(&cache->lock);
9355 	spin_unlock(&sinfo->lock);
9356 	return ret;
9357 }
9358 
9359 int btrfs_inc_block_group_ro(struct btrfs_root *root,
9360 			     struct btrfs_block_group_cache *cache)
9361 
9362 {
9363 	struct btrfs_fs_info *fs_info = root->fs_info;
9364 	struct btrfs_trans_handle *trans;
9365 	u64 alloc_flags;
9366 	int ret;
9367 
9368 again:
9369 	trans = btrfs_join_transaction(root);
9370 	if (IS_ERR(trans))
9371 		return PTR_ERR(trans);
9372 
9373 	/*
9374 	 * we're not allowed to set block groups readonly after the dirty
9375 	 * block groups cache has started writing.  If it already started,
9376 	 * back off and let this transaction commit
9377 	 */
9378 	mutex_lock(&fs_info->ro_block_group_mutex);
9379 	if (test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &trans->transaction->flags)) {
9380 		u64 transid = trans->transid;
9381 
9382 		mutex_unlock(&fs_info->ro_block_group_mutex);
9383 		btrfs_end_transaction(trans);
9384 
9385 		ret = btrfs_wait_for_commit(fs_info, transid);
9386 		if (ret)
9387 			return ret;
9388 		goto again;
9389 	}
9390 
9391 	/*
9392 	 * if we are changing raid levels, try to allocate a corresponding
9393 	 * block group with the new raid level.
9394 	 */
9395 	alloc_flags = update_block_group_flags(fs_info, cache->flags);
9396 	if (alloc_flags != cache->flags) {
9397 		ret = do_chunk_alloc(trans, fs_info, alloc_flags,
9398 				     CHUNK_ALLOC_FORCE);
9399 		/*
9400 		 * ENOSPC is allowed here, we may have enough space
9401 		 * already allocated at the new raid level to
9402 		 * carry on
9403 		 */
9404 		if (ret == -ENOSPC)
9405 			ret = 0;
9406 		if (ret < 0)
9407 			goto out;
9408 	}
9409 
9410 	ret = inc_block_group_ro(cache, 0);
9411 	if (!ret)
9412 		goto out;
9413 	alloc_flags = get_alloc_profile(fs_info, cache->space_info->flags);
9414 	ret = do_chunk_alloc(trans, fs_info, alloc_flags,
9415 			     CHUNK_ALLOC_FORCE);
9416 	if (ret < 0)
9417 		goto out;
9418 	ret = inc_block_group_ro(cache, 0);
9419 out:
9420 	if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
9421 		alloc_flags = update_block_group_flags(fs_info, cache->flags);
9422 		mutex_lock(&fs_info->chunk_mutex);
9423 		check_system_chunk(trans, fs_info, alloc_flags);
9424 		mutex_unlock(&fs_info->chunk_mutex);
9425 	}
9426 	mutex_unlock(&fs_info->ro_block_group_mutex);
9427 
9428 	btrfs_end_transaction(trans);
9429 	return ret;
9430 }
9431 
9432 int btrfs_force_chunk_alloc(struct btrfs_trans_handle *trans,
9433 			    struct btrfs_fs_info *fs_info, u64 type)
9434 {
9435 	u64 alloc_flags = get_alloc_profile(fs_info, type);
9436 
9437 	return do_chunk_alloc(trans, fs_info, alloc_flags, CHUNK_ALLOC_FORCE);
9438 }
9439 
9440 /*
9441  * helper to account the unused space of all the readonly block group in the
9442  * space_info. takes mirrors into account.
9443  */
9444 u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
9445 {
9446 	struct btrfs_block_group_cache *block_group;
9447 	u64 free_bytes = 0;
9448 	int factor;
9449 
9450 	/* It's df, we don't care if it's racy */
9451 	if (list_empty(&sinfo->ro_bgs))
9452 		return 0;
9453 
9454 	spin_lock(&sinfo->lock);
9455 	list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
9456 		spin_lock(&block_group->lock);
9457 
9458 		if (!block_group->ro) {
9459 			spin_unlock(&block_group->lock);
9460 			continue;
9461 		}
9462 
9463 		if (block_group->flags & (BTRFS_BLOCK_GROUP_RAID1 |
9464 					  BTRFS_BLOCK_GROUP_RAID10 |
9465 					  BTRFS_BLOCK_GROUP_DUP))
9466 			factor = 2;
9467 		else
9468 			factor = 1;
9469 
9470 		free_bytes += (block_group->key.offset -
9471 			       btrfs_block_group_used(&block_group->item)) *
9472 			       factor;
9473 
9474 		spin_unlock(&block_group->lock);
9475 	}
9476 	spin_unlock(&sinfo->lock);
9477 
9478 	return free_bytes;
9479 }
9480 
9481 void btrfs_dec_block_group_ro(struct btrfs_block_group_cache *cache)
9482 {
9483 	struct btrfs_space_info *sinfo = cache->space_info;
9484 	u64 num_bytes;
9485 
9486 	BUG_ON(!cache->ro);
9487 
9488 	spin_lock(&sinfo->lock);
9489 	spin_lock(&cache->lock);
9490 	if (!--cache->ro) {
9491 		num_bytes = cache->key.offset - cache->reserved -
9492 			    cache->pinned - cache->bytes_super -
9493 			    btrfs_block_group_used(&cache->item);
9494 		sinfo->bytes_readonly -= num_bytes;
9495 		list_del_init(&cache->ro_list);
9496 	}
9497 	spin_unlock(&cache->lock);
9498 	spin_unlock(&sinfo->lock);
9499 }
9500 
9501 /*
9502  * checks to see if its even possible to relocate this block group.
9503  *
9504  * @return - -1 if it's not a good idea to relocate this block group, 0 if its
9505  * ok to go ahead and try.
9506  */
9507 int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
9508 {
9509 	struct btrfs_root *root = fs_info->extent_root;
9510 	struct btrfs_block_group_cache *block_group;
9511 	struct btrfs_space_info *space_info;
9512 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
9513 	struct btrfs_device *device;
9514 	struct btrfs_trans_handle *trans;
9515 	u64 min_free;
9516 	u64 dev_min = 1;
9517 	u64 dev_nr = 0;
9518 	u64 target;
9519 	int debug;
9520 	int index;
9521 	int full = 0;
9522 	int ret = 0;
9523 
9524 	debug = btrfs_test_opt(fs_info, ENOSPC_DEBUG);
9525 
9526 	block_group = btrfs_lookup_block_group(fs_info, bytenr);
9527 
9528 	/* odd, couldn't find the block group, leave it alone */
9529 	if (!block_group) {
9530 		if (debug)
9531 			btrfs_warn(fs_info,
9532 				   "can't find block group for bytenr %llu",
9533 				   bytenr);
9534 		return -1;
9535 	}
9536 
9537 	min_free = btrfs_block_group_used(&block_group->item);
9538 
9539 	/* no bytes used, we're good */
9540 	if (!min_free)
9541 		goto out;
9542 
9543 	space_info = block_group->space_info;
9544 	spin_lock(&space_info->lock);
9545 
9546 	full = space_info->full;
9547 
9548 	/*
9549 	 * if this is the last block group we have in this space, we can't
9550 	 * relocate it unless we're able to allocate a new chunk below.
9551 	 *
9552 	 * Otherwise, we need to make sure we have room in the space to handle
9553 	 * all of the extents from this block group.  If we can, we're good
9554 	 */
9555 	if ((space_info->total_bytes != block_group->key.offset) &&
9556 	    (space_info->bytes_used + space_info->bytes_reserved +
9557 	     space_info->bytes_pinned + space_info->bytes_readonly +
9558 	     min_free < space_info->total_bytes)) {
9559 		spin_unlock(&space_info->lock);
9560 		goto out;
9561 	}
9562 	spin_unlock(&space_info->lock);
9563 
9564 	/*
9565 	 * ok we don't have enough space, but maybe we have free space on our
9566 	 * devices to allocate new chunks for relocation, so loop through our
9567 	 * alloc devices and guess if we have enough space.  if this block
9568 	 * group is going to be restriped, run checks against the target
9569 	 * profile instead of the current one.
9570 	 */
9571 	ret = -1;
9572 
9573 	/*
9574 	 * index:
9575 	 *      0: raid10
9576 	 *      1: raid1
9577 	 *      2: dup
9578 	 *      3: raid0
9579 	 *      4: single
9580 	 */
9581 	target = get_restripe_target(fs_info, block_group->flags);
9582 	if (target) {
9583 		index = __get_raid_index(extended_to_chunk(target));
9584 	} else {
9585 		/*
9586 		 * this is just a balance, so if we were marked as full
9587 		 * we know there is no space for a new chunk
9588 		 */
9589 		if (full) {
9590 			if (debug)
9591 				btrfs_warn(fs_info,
9592 					   "no space to alloc new chunk for block group %llu",
9593 					   block_group->key.objectid);
9594 			goto out;
9595 		}
9596 
9597 		index = get_block_group_index(block_group);
9598 	}
9599 
9600 	if (index == BTRFS_RAID_RAID10) {
9601 		dev_min = 4;
9602 		/* Divide by 2 */
9603 		min_free >>= 1;
9604 	} else if (index == BTRFS_RAID_RAID1) {
9605 		dev_min = 2;
9606 	} else if (index == BTRFS_RAID_DUP) {
9607 		/* Multiply by 2 */
9608 		min_free <<= 1;
9609 	} else if (index == BTRFS_RAID_RAID0) {
9610 		dev_min = fs_devices->rw_devices;
9611 		min_free = div64_u64(min_free, dev_min);
9612 	}
9613 
9614 	/* We need to do this so that we can look at pending chunks */
9615 	trans = btrfs_join_transaction(root);
9616 	if (IS_ERR(trans)) {
9617 		ret = PTR_ERR(trans);
9618 		goto out;
9619 	}
9620 
9621 	mutex_lock(&fs_info->chunk_mutex);
9622 	list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
9623 		u64 dev_offset;
9624 
9625 		/*
9626 		 * check to make sure we can actually find a chunk with enough
9627 		 * space to fit our block group in.
9628 		 */
9629 		if (device->total_bytes > device->bytes_used + min_free &&
9630 		    !device->is_tgtdev_for_dev_replace) {
9631 			ret = find_free_dev_extent(trans, device, min_free,
9632 						   &dev_offset, NULL);
9633 			if (!ret)
9634 				dev_nr++;
9635 
9636 			if (dev_nr >= dev_min)
9637 				break;
9638 
9639 			ret = -1;
9640 		}
9641 	}
9642 	if (debug && ret == -1)
9643 		btrfs_warn(fs_info,
9644 			   "no space to allocate a new chunk for block group %llu",
9645 			   block_group->key.objectid);
9646 	mutex_unlock(&fs_info->chunk_mutex);
9647 	btrfs_end_transaction(trans);
9648 out:
9649 	btrfs_put_block_group(block_group);
9650 	return ret;
9651 }
9652 
9653 static int find_first_block_group(struct btrfs_fs_info *fs_info,
9654 				  struct btrfs_path *path,
9655 				  struct btrfs_key *key)
9656 {
9657 	struct btrfs_root *root = fs_info->extent_root;
9658 	int ret = 0;
9659 	struct btrfs_key found_key;
9660 	struct extent_buffer *leaf;
9661 	int slot;
9662 
9663 	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
9664 	if (ret < 0)
9665 		goto out;
9666 
9667 	while (1) {
9668 		slot = path->slots[0];
9669 		leaf = path->nodes[0];
9670 		if (slot >= btrfs_header_nritems(leaf)) {
9671 			ret = btrfs_next_leaf(root, path);
9672 			if (ret == 0)
9673 				continue;
9674 			if (ret < 0)
9675 				goto out;
9676 			break;
9677 		}
9678 		btrfs_item_key_to_cpu(leaf, &found_key, slot);
9679 
9680 		if (found_key.objectid >= key->objectid &&
9681 		    found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
9682 			struct extent_map_tree *em_tree;
9683 			struct extent_map *em;
9684 
9685 			em_tree = &root->fs_info->mapping_tree.map_tree;
9686 			read_lock(&em_tree->lock);
9687 			em = lookup_extent_mapping(em_tree, found_key.objectid,
9688 						   found_key.offset);
9689 			read_unlock(&em_tree->lock);
9690 			if (!em) {
9691 				btrfs_err(fs_info,
9692 			"logical %llu len %llu found bg but no related chunk",
9693 					  found_key.objectid, found_key.offset);
9694 				ret = -ENOENT;
9695 			} else {
9696 				ret = 0;
9697 			}
9698 			free_extent_map(em);
9699 			goto out;
9700 		}
9701 		path->slots[0]++;
9702 	}
9703 out:
9704 	return ret;
9705 }
9706 
9707 void btrfs_put_block_group_cache(struct btrfs_fs_info *info)
9708 {
9709 	struct btrfs_block_group_cache *block_group;
9710 	u64 last = 0;
9711 
9712 	while (1) {
9713 		struct inode *inode;
9714 
9715 		block_group = btrfs_lookup_first_block_group(info, last);
9716 		while (block_group) {
9717 			spin_lock(&block_group->lock);
9718 			if (block_group->iref)
9719 				break;
9720 			spin_unlock(&block_group->lock);
9721 			block_group = next_block_group(info, block_group);
9722 		}
9723 		if (!block_group) {
9724 			if (last == 0)
9725 				break;
9726 			last = 0;
9727 			continue;
9728 		}
9729 
9730 		inode = block_group->inode;
9731 		block_group->iref = 0;
9732 		block_group->inode = NULL;
9733 		spin_unlock(&block_group->lock);
9734 		ASSERT(block_group->io_ctl.inode == NULL);
9735 		iput(inode);
9736 		last = block_group->key.objectid + block_group->key.offset;
9737 		btrfs_put_block_group(block_group);
9738 	}
9739 }
9740 
9741 int btrfs_free_block_groups(struct btrfs_fs_info *info)
9742 {
9743 	struct btrfs_block_group_cache *block_group;
9744 	struct btrfs_space_info *space_info;
9745 	struct btrfs_caching_control *caching_ctl;
9746 	struct rb_node *n;
9747 
9748 	down_write(&info->commit_root_sem);
9749 	while (!list_empty(&info->caching_block_groups)) {
9750 		caching_ctl = list_entry(info->caching_block_groups.next,
9751 					 struct btrfs_caching_control, list);
9752 		list_del(&caching_ctl->list);
9753 		put_caching_control(caching_ctl);
9754 	}
9755 	up_write(&info->commit_root_sem);
9756 
9757 	spin_lock(&info->unused_bgs_lock);
9758 	while (!list_empty(&info->unused_bgs)) {
9759 		block_group = list_first_entry(&info->unused_bgs,
9760 					       struct btrfs_block_group_cache,
9761 					       bg_list);
9762 		list_del_init(&block_group->bg_list);
9763 		btrfs_put_block_group(block_group);
9764 	}
9765 	spin_unlock(&info->unused_bgs_lock);
9766 
9767 	spin_lock(&info->block_group_cache_lock);
9768 	while ((n = rb_last(&info->block_group_cache_tree)) != NULL) {
9769 		block_group = rb_entry(n, struct btrfs_block_group_cache,
9770 				       cache_node);
9771 		rb_erase(&block_group->cache_node,
9772 			 &info->block_group_cache_tree);
9773 		RB_CLEAR_NODE(&block_group->cache_node);
9774 		spin_unlock(&info->block_group_cache_lock);
9775 
9776 		down_write(&block_group->space_info->groups_sem);
9777 		list_del(&block_group->list);
9778 		up_write(&block_group->space_info->groups_sem);
9779 
9780 		if (block_group->cached == BTRFS_CACHE_STARTED)
9781 			wait_block_group_cache_done(block_group);
9782 
9783 		/*
9784 		 * We haven't cached this block group, which means we could
9785 		 * possibly have excluded extents on this block group.
9786 		 */
9787 		if (block_group->cached == BTRFS_CACHE_NO ||
9788 		    block_group->cached == BTRFS_CACHE_ERROR)
9789 			free_excluded_extents(info, block_group);
9790 
9791 		btrfs_remove_free_space_cache(block_group);
9792 		ASSERT(list_empty(&block_group->dirty_list));
9793 		ASSERT(list_empty(&block_group->io_list));
9794 		ASSERT(list_empty(&block_group->bg_list));
9795 		ASSERT(atomic_read(&block_group->count) == 1);
9796 		btrfs_put_block_group(block_group);
9797 
9798 		spin_lock(&info->block_group_cache_lock);
9799 	}
9800 	spin_unlock(&info->block_group_cache_lock);
9801 
9802 	/* now that all the block groups are freed, go through and
9803 	 * free all the space_info structs.  This is only called during
9804 	 * the final stages of unmount, and so we know nobody is
9805 	 * using them.  We call synchronize_rcu() once before we start,
9806 	 * just to be on the safe side.
9807 	 */
9808 	synchronize_rcu();
9809 
9810 	release_global_block_rsv(info);
9811 
9812 	while (!list_empty(&info->space_info)) {
9813 		int i;
9814 
9815 		space_info = list_entry(info->space_info.next,
9816 					struct btrfs_space_info,
9817 					list);
9818 
9819 		/*
9820 		 * Do not hide this behind enospc_debug, this is actually
9821 		 * important and indicates a real bug if this happens.
9822 		 */
9823 		if (WARN_ON(space_info->bytes_pinned > 0 ||
9824 			    space_info->bytes_reserved > 0 ||
9825 			    space_info->bytes_may_use > 0))
9826 			dump_space_info(info, space_info, 0, 0);
9827 		list_del(&space_info->list);
9828 		for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
9829 			struct kobject *kobj;
9830 			kobj = space_info->block_group_kobjs[i];
9831 			space_info->block_group_kobjs[i] = NULL;
9832 			if (kobj) {
9833 				kobject_del(kobj);
9834 				kobject_put(kobj);
9835 			}
9836 		}
9837 		kobject_del(&space_info->kobj);
9838 		kobject_put(&space_info->kobj);
9839 	}
9840 	return 0;
9841 }
9842 
9843 static void __link_block_group(struct btrfs_space_info *space_info,
9844 			       struct btrfs_block_group_cache *cache)
9845 {
9846 	int index = get_block_group_index(cache);
9847 	bool first = false;
9848 
9849 	down_write(&space_info->groups_sem);
9850 	if (list_empty(&space_info->block_groups[index]))
9851 		first = true;
9852 	list_add_tail(&cache->list, &space_info->block_groups[index]);
9853 	up_write(&space_info->groups_sem);
9854 
9855 	if (first) {
9856 		struct raid_kobject *rkobj;
9857 		int ret;
9858 
9859 		rkobj = kzalloc(sizeof(*rkobj), GFP_NOFS);
9860 		if (!rkobj)
9861 			goto out_err;
9862 		rkobj->raid_type = index;
9863 		kobject_init(&rkobj->kobj, &btrfs_raid_ktype);
9864 		ret = kobject_add(&rkobj->kobj, &space_info->kobj,
9865 				  "%s", get_raid_name(index));
9866 		if (ret) {
9867 			kobject_put(&rkobj->kobj);
9868 			goto out_err;
9869 		}
9870 		space_info->block_group_kobjs[index] = &rkobj->kobj;
9871 	}
9872 
9873 	return;
9874 out_err:
9875 	btrfs_warn(cache->fs_info,
9876 		   "failed to add kobject for block cache, ignoring");
9877 }
9878 
9879 static struct btrfs_block_group_cache *
9880 btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info,
9881 			       u64 start, u64 size)
9882 {
9883 	struct btrfs_block_group_cache *cache;
9884 
9885 	cache = kzalloc(sizeof(*cache), GFP_NOFS);
9886 	if (!cache)
9887 		return NULL;
9888 
9889 	cache->free_space_ctl = kzalloc(sizeof(*cache->free_space_ctl),
9890 					GFP_NOFS);
9891 	if (!cache->free_space_ctl) {
9892 		kfree(cache);
9893 		return NULL;
9894 	}
9895 
9896 	cache->key.objectid = start;
9897 	cache->key.offset = size;
9898 	cache->key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
9899 
9900 	cache->sectorsize = fs_info->sectorsize;
9901 	cache->fs_info = fs_info;
9902 	cache->full_stripe_len = btrfs_full_stripe_len(fs_info,
9903 						       &fs_info->mapping_tree,
9904 						       start);
9905 	set_free_space_tree_thresholds(cache);
9906 
9907 	atomic_set(&cache->count, 1);
9908 	spin_lock_init(&cache->lock);
9909 	init_rwsem(&cache->data_rwsem);
9910 	INIT_LIST_HEAD(&cache->list);
9911 	INIT_LIST_HEAD(&cache->cluster_list);
9912 	INIT_LIST_HEAD(&cache->bg_list);
9913 	INIT_LIST_HEAD(&cache->ro_list);
9914 	INIT_LIST_HEAD(&cache->dirty_list);
9915 	INIT_LIST_HEAD(&cache->io_list);
9916 	btrfs_init_free_space_ctl(cache);
9917 	atomic_set(&cache->trimming, 0);
9918 	mutex_init(&cache->free_space_lock);
9919 
9920 	return cache;
9921 }
9922 
9923 int btrfs_read_block_groups(struct btrfs_fs_info *info)
9924 {
9925 	struct btrfs_path *path;
9926 	int ret;
9927 	struct btrfs_block_group_cache *cache;
9928 	struct btrfs_space_info *space_info;
9929 	struct btrfs_key key;
9930 	struct btrfs_key found_key;
9931 	struct extent_buffer *leaf;
9932 	int need_clear = 0;
9933 	u64 cache_gen;
9934 	u64 feature;
9935 	int mixed;
9936 
9937 	feature = btrfs_super_incompat_flags(info->super_copy);
9938 	mixed = !!(feature & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS);
9939 
9940 	key.objectid = 0;
9941 	key.offset = 0;
9942 	key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
9943 	path = btrfs_alloc_path();
9944 	if (!path)
9945 		return -ENOMEM;
9946 	path->reada = READA_FORWARD;
9947 
9948 	cache_gen = btrfs_super_cache_generation(info->super_copy);
9949 	if (btrfs_test_opt(info, SPACE_CACHE) &&
9950 	    btrfs_super_generation(info->super_copy) != cache_gen)
9951 		need_clear = 1;
9952 	if (btrfs_test_opt(info, CLEAR_CACHE))
9953 		need_clear = 1;
9954 
9955 	while (1) {
9956 		ret = find_first_block_group(info, path, &key);
9957 		if (ret > 0)
9958 			break;
9959 		if (ret != 0)
9960 			goto error;
9961 
9962 		leaf = path->nodes[0];
9963 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
9964 
9965 		cache = btrfs_create_block_group_cache(info, found_key.objectid,
9966 						       found_key.offset);
9967 		if (!cache) {
9968 			ret = -ENOMEM;
9969 			goto error;
9970 		}
9971 
9972 		if (need_clear) {
9973 			/*
9974 			 * When we mount with old space cache, we need to
9975 			 * set BTRFS_DC_CLEAR and set dirty flag.
9976 			 *
9977 			 * a) Setting 'BTRFS_DC_CLEAR' makes sure that we
9978 			 *    truncate the old free space cache inode and
9979 			 *    setup a new one.
9980 			 * b) Setting 'dirty flag' makes sure that we flush
9981 			 *    the new space cache info onto disk.
9982 			 */
9983 			if (btrfs_test_opt(info, SPACE_CACHE))
9984 				cache->disk_cache_state = BTRFS_DC_CLEAR;
9985 		}
9986 
9987 		read_extent_buffer(leaf, &cache->item,
9988 				   btrfs_item_ptr_offset(leaf, path->slots[0]),
9989 				   sizeof(cache->item));
9990 		cache->flags = btrfs_block_group_flags(&cache->item);
9991 		if (!mixed &&
9992 		    ((cache->flags & BTRFS_BLOCK_GROUP_METADATA) &&
9993 		    (cache->flags & BTRFS_BLOCK_GROUP_DATA))) {
9994 			btrfs_err(info,
9995 "bg %llu is a mixed block group but filesystem hasn't enabled mixed block groups",
9996 				  cache->key.objectid);
9997 			ret = -EINVAL;
9998 			goto error;
9999 		}
10000 
10001 		key.objectid = found_key.objectid + found_key.offset;
10002 		btrfs_release_path(path);
10003 
10004 		/*
10005 		 * We need to exclude the super stripes now so that the space
10006 		 * info has super bytes accounted for, otherwise we'll think
10007 		 * we have more space than we actually do.
10008 		 */
10009 		ret = exclude_super_stripes(info, cache);
10010 		if (ret) {
10011 			/*
10012 			 * We may have excluded something, so call this just in
10013 			 * case.
10014 			 */
10015 			free_excluded_extents(info, cache);
10016 			btrfs_put_block_group(cache);
10017 			goto error;
10018 		}
10019 
10020 		/*
10021 		 * check for two cases, either we are full, and therefore
10022 		 * don't need to bother with the caching work since we won't
10023 		 * find any space, or we are empty, and we can just add all
10024 		 * the space in and be done with it.  This saves us _alot_ of
10025 		 * time, particularly in the full case.
10026 		 */
10027 		if (found_key.offset == btrfs_block_group_used(&cache->item)) {
10028 			cache->last_byte_to_unpin = (u64)-1;
10029 			cache->cached = BTRFS_CACHE_FINISHED;
10030 			free_excluded_extents(info, cache);
10031 		} else if (btrfs_block_group_used(&cache->item) == 0) {
10032 			cache->last_byte_to_unpin = (u64)-1;
10033 			cache->cached = BTRFS_CACHE_FINISHED;
10034 			add_new_free_space(cache, info,
10035 					   found_key.objectid,
10036 					   found_key.objectid +
10037 					   found_key.offset);
10038 			free_excluded_extents(info, cache);
10039 		}
10040 
10041 		ret = btrfs_add_block_group_cache(info, cache);
10042 		if (ret) {
10043 			btrfs_remove_free_space_cache(cache);
10044 			btrfs_put_block_group(cache);
10045 			goto error;
10046 		}
10047 
10048 		trace_btrfs_add_block_group(info, cache, 0);
10049 		ret = update_space_info(info, cache->flags, found_key.offset,
10050 					btrfs_block_group_used(&cache->item),
10051 					cache->bytes_super, &space_info);
10052 		if (ret) {
10053 			btrfs_remove_free_space_cache(cache);
10054 			spin_lock(&info->block_group_cache_lock);
10055 			rb_erase(&cache->cache_node,
10056 				 &info->block_group_cache_tree);
10057 			RB_CLEAR_NODE(&cache->cache_node);
10058 			spin_unlock(&info->block_group_cache_lock);
10059 			btrfs_put_block_group(cache);
10060 			goto error;
10061 		}
10062 
10063 		cache->space_info = space_info;
10064 
10065 		__link_block_group(space_info, cache);
10066 
10067 		set_avail_alloc_bits(info, cache->flags);
10068 		if (btrfs_chunk_readonly(info, cache->key.objectid)) {
10069 			inc_block_group_ro(cache, 1);
10070 		} else if (btrfs_block_group_used(&cache->item) == 0) {
10071 			spin_lock(&info->unused_bgs_lock);
10072 			/* Should always be true but just in case. */
10073 			if (list_empty(&cache->bg_list)) {
10074 				btrfs_get_block_group(cache);
10075 				list_add_tail(&cache->bg_list,
10076 					      &info->unused_bgs);
10077 			}
10078 			spin_unlock(&info->unused_bgs_lock);
10079 		}
10080 	}
10081 
10082 	list_for_each_entry_rcu(space_info, &info->space_info, list) {
10083 		if (!(get_alloc_profile(info, space_info->flags) &
10084 		      (BTRFS_BLOCK_GROUP_RAID10 |
10085 		       BTRFS_BLOCK_GROUP_RAID1 |
10086 		       BTRFS_BLOCK_GROUP_RAID5 |
10087 		       BTRFS_BLOCK_GROUP_RAID6 |
10088 		       BTRFS_BLOCK_GROUP_DUP)))
10089 			continue;
10090 		/*
10091 		 * avoid allocating from un-mirrored block group if there are
10092 		 * mirrored block groups.
10093 		 */
10094 		list_for_each_entry(cache,
10095 				&space_info->block_groups[BTRFS_RAID_RAID0],
10096 				list)
10097 			inc_block_group_ro(cache, 1);
10098 		list_for_each_entry(cache,
10099 				&space_info->block_groups[BTRFS_RAID_SINGLE],
10100 				list)
10101 			inc_block_group_ro(cache, 1);
10102 	}
10103 
10104 	init_global_block_rsv(info);
10105 	ret = 0;
10106 error:
10107 	btrfs_free_path(path);
10108 	return ret;
10109 }
10110 
10111 void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans,
10112 				       struct btrfs_fs_info *fs_info)
10113 {
10114 	struct btrfs_block_group_cache *block_group, *tmp;
10115 	struct btrfs_root *extent_root = fs_info->extent_root;
10116 	struct btrfs_block_group_item item;
10117 	struct btrfs_key key;
10118 	int ret = 0;
10119 	bool can_flush_pending_bgs = trans->can_flush_pending_bgs;
10120 
10121 	trans->can_flush_pending_bgs = false;
10122 	list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
10123 		if (ret)
10124 			goto next;
10125 
10126 		spin_lock(&block_group->lock);
10127 		memcpy(&item, &block_group->item, sizeof(item));
10128 		memcpy(&key, &block_group->key, sizeof(key));
10129 		spin_unlock(&block_group->lock);
10130 
10131 		ret = btrfs_insert_item(trans, extent_root, &key, &item,
10132 					sizeof(item));
10133 		if (ret)
10134 			btrfs_abort_transaction(trans, ret);
10135 		ret = btrfs_finish_chunk_alloc(trans, fs_info, key.objectid,
10136 					       key.offset);
10137 		if (ret)
10138 			btrfs_abort_transaction(trans, ret);
10139 		add_block_group_free_space(trans, fs_info, block_group);
10140 		/* already aborted the transaction if it failed. */
10141 next:
10142 		list_del_init(&block_group->bg_list);
10143 	}
10144 	trans->can_flush_pending_bgs = can_flush_pending_bgs;
10145 }
10146 
10147 int btrfs_make_block_group(struct btrfs_trans_handle *trans,
10148 			   struct btrfs_fs_info *fs_info, u64 bytes_used,
10149 			   u64 type, u64 chunk_objectid, u64 chunk_offset,
10150 			   u64 size)
10151 {
10152 	struct btrfs_block_group_cache *cache;
10153 	int ret;
10154 
10155 	btrfs_set_log_full_commit(fs_info, trans);
10156 
10157 	cache = btrfs_create_block_group_cache(fs_info, chunk_offset, size);
10158 	if (!cache)
10159 		return -ENOMEM;
10160 
10161 	btrfs_set_block_group_used(&cache->item, bytes_used);
10162 	btrfs_set_block_group_chunk_objectid(&cache->item, chunk_objectid);
10163 	btrfs_set_block_group_flags(&cache->item, type);
10164 
10165 	cache->flags = type;
10166 	cache->last_byte_to_unpin = (u64)-1;
10167 	cache->cached = BTRFS_CACHE_FINISHED;
10168 	cache->needs_free_space = 1;
10169 	ret = exclude_super_stripes(fs_info, cache);
10170 	if (ret) {
10171 		/*
10172 		 * We may have excluded something, so call this just in
10173 		 * case.
10174 		 */
10175 		free_excluded_extents(fs_info, cache);
10176 		btrfs_put_block_group(cache);
10177 		return ret;
10178 	}
10179 
10180 	add_new_free_space(cache, fs_info, chunk_offset, chunk_offset + size);
10181 
10182 	free_excluded_extents(fs_info, cache);
10183 
10184 #ifdef CONFIG_BTRFS_DEBUG
10185 	if (btrfs_should_fragment_free_space(cache)) {
10186 		u64 new_bytes_used = size - bytes_used;
10187 
10188 		bytes_used += new_bytes_used >> 1;
10189 		fragment_free_space(cache);
10190 	}
10191 #endif
10192 	/*
10193 	 * Call to ensure the corresponding space_info object is created and
10194 	 * assigned to our block group, but don't update its counters just yet.
10195 	 * We want our bg to be added to the rbtree with its ->space_info set.
10196 	 */
10197 	ret = update_space_info(fs_info, cache->flags, 0, 0, 0,
10198 				&cache->space_info);
10199 	if (ret) {
10200 		btrfs_remove_free_space_cache(cache);
10201 		btrfs_put_block_group(cache);
10202 		return ret;
10203 	}
10204 
10205 	ret = btrfs_add_block_group_cache(fs_info, cache);
10206 	if (ret) {
10207 		btrfs_remove_free_space_cache(cache);
10208 		btrfs_put_block_group(cache);
10209 		return ret;
10210 	}
10211 
10212 	/*
10213 	 * Now that our block group has its ->space_info set and is inserted in
10214 	 * the rbtree, update the space info's counters.
10215 	 */
10216 	trace_btrfs_add_block_group(fs_info, cache, 1);
10217 	ret = update_space_info(fs_info, cache->flags, size, bytes_used,
10218 				cache->bytes_super, &cache->space_info);
10219 	if (ret) {
10220 		btrfs_remove_free_space_cache(cache);
10221 		spin_lock(&fs_info->block_group_cache_lock);
10222 		rb_erase(&cache->cache_node,
10223 			 &fs_info->block_group_cache_tree);
10224 		RB_CLEAR_NODE(&cache->cache_node);
10225 		spin_unlock(&fs_info->block_group_cache_lock);
10226 		btrfs_put_block_group(cache);
10227 		return ret;
10228 	}
10229 	update_global_block_rsv(fs_info);
10230 
10231 	__link_block_group(cache->space_info, cache);
10232 
10233 	list_add_tail(&cache->bg_list, &trans->new_bgs);
10234 
10235 	set_avail_alloc_bits(fs_info, type);
10236 	return 0;
10237 }
10238 
10239 static void clear_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
10240 {
10241 	u64 extra_flags = chunk_to_extended(flags) &
10242 				BTRFS_EXTENDED_PROFILE_MASK;
10243 
10244 	write_seqlock(&fs_info->profiles_lock);
10245 	if (flags & BTRFS_BLOCK_GROUP_DATA)
10246 		fs_info->avail_data_alloc_bits &= ~extra_flags;
10247 	if (flags & BTRFS_BLOCK_GROUP_METADATA)
10248 		fs_info->avail_metadata_alloc_bits &= ~extra_flags;
10249 	if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
10250 		fs_info->avail_system_alloc_bits &= ~extra_flags;
10251 	write_sequnlock(&fs_info->profiles_lock);
10252 }
10253 
10254 int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
10255 			     struct btrfs_fs_info *fs_info, u64 group_start,
10256 			     struct extent_map *em)
10257 {
10258 	struct btrfs_root *root = fs_info->extent_root;
10259 	struct btrfs_path *path;
10260 	struct btrfs_block_group_cache *block_group;
10261 	struct btrfs_free_cluster *cluster;
10262 	struct btrfs_root *tree_root = fs_info->tree_root;
10263 	struct btrfs_key key;
10264 	struct inode *inode;
10265 	struct kobject *kobj = NULL;
10266 	int ret;
10267 	int index;
10268 	int factor;
10269 	struct btrfs_caching_control *caching_ctl = NULL;
10270 	bool remove_em;
10271 
10272 	block_group = btrfs_lookup_block_group(fs_info, group_start);
10273 	BUG_ON(!block_group);
10274 	BUG_ON(!block_group->ro);
10275 
10276 	/*
10277 	 * Free the reserved super bytes from this block group before
10278 	 * remove it.
10279 	 */
10280 	free_excluded_extents(fs_info, block_group);
10281 
10282 	memcpy(&key, &block_group->key, sizeof(key));
10283 	index = get_block_group_index(block_group);
10284 	if (block_group->flags & (BTRFS_BLOCK_GROUP_DUP |
10285 				  BTRFS_BLOCK_GROUP_RAID1 |
10286 				  BTRFS_BLOCK_GROUP_RAID10))
10287 		factor = 2;
10288 	else
10289 		factor = 1;
10290 
10291 	/* make sure this block group isn't part of an allocation cluster */
10292 	cluster = &fs_info->data_alloc_cluster;
10293 	spin_lock(&cluster->refill_lock);
10294 	btrfs_return_cluster_to_free_space(block_group, cluster);
10295 	spin_unlock(&cluster->refill_lock);
10296 
10297 	/*
10298 	 * make sure this block group isn't part of a metadata
10299 	 * allocation cluster
10300 	 */
10301 	cluster = &fs_info->meta_alloc_cluster;
10302 	spin_lock(&cluster->refill_lock);
10303 	btrfs_return_cluster_to_free_space(block_group, cluster);
10304 	spin_unlock(&cluster->refill_lock);
10305 
10306 	path = btrfs_alloc_path();
10307 	if (!path) {
10308 		ret = -ENOMEM;
10309 		goto out;
10310 	}
10311 
10312 	/*
10313 	 * get the inode first so any iput calls done for the io_list
10314 	 * aren't the final iput (no unlinks allowed now)
10315 	 */
10316 	inode = lookup_free_space_inode(tree_root, block_group, path);
10317 
10318 	mutex_lock(&trans->transaction->cache_write_mutex);
10319 	/*
10320 	 * make sure our free spache cache IO is done before remove the
10321 	 * free space inode
10322 	 */
10323 	spin_lock(&trans->transaction->dirty_bgs_lock);
10324 	if (!list_empty(&block_group->io_list)) {
10325 		list_del_init(&block_group->io_list);
10326 
10327 		WARN_ON(!IS_ERR(inode) && inode != block_group->io_ctl.inode);
10328 
10329 		spin_unlock(&trans->transaction->dirty_bgs_lock);
10330 		btrfs_wait_cache_io(trans, block_group, path);
10331 		btrfs_put_block_group(block_group);
10332 		spin_lock(&trans->transaction->dirty_bgs_lock);
10333 	}
10334 
10335 	if (!list_empty(&block_group->dirty_list)) {
10336 		list_del_init(&block_group->dirty_list);
10337 		btrfs_put_block_group(block_group);
10338 	}
10339 	spin_unlock(&trans->transaction->dirty_bgs_lock);
10340 	mutex_unlock(&trans->transaction->cache_write_mutex);
10341 
10342 	if (!IS_ERR(inode)) {
10343 		ret = btrfs_orphan_add(trans, inode);
10344 		if (ret) {
10345 			btrfs_add_delayed_iput(inode);
10346 			goto out;
10347 		}
10348 		clear_nlink(inode);
10349 		/* One for the block groups ref */
10350 		spin_lock(&block_group->lock);
10351 		if (block_group->iref) {
10352 			block_group->iref = 0;
10353 			block_group->inode = NULL;
10354 			spin_unlock(&block_group->lock);
10355 			iput(inode);
10356 		} else {
10357 			spin_unlock(&block_group->lock);
10358 		}
10359 		/* One for our lookup ref */
10360 		btrfs_add_delayed_iput(inode);
10361 	}
10362 
10363 	key.objectid = BTRFS_FREE_SPACE_OBJECTID;
10364 	key.offset = block_group->key.objectid;
10365 	key.type = 0;
10366 
10367 	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
10368 	if (ret < 0)
10369 		goto out;
10370 	if (ret > 0)
10371 		btrfs_release_path(path);
10372 	if (ret == 0) {
10373 		ret = btrfs_del_item(trans, tree_root, path);
10374 		if (ret)
10375 			goto out;
10376 		btrfs_release_path(path);
10377 	}
10378 
10379 	spin_lock(&fs_info->block_group_cache_lock);
10380 	rb_erase(&block_group->cache_node,
10381 		 &fs_info->block_group_cache_tree);
10382 	RB_CLEAR_NODE(&block_group->cache_node);
10383 
10384 	if (fs_info->first_logical_byte == block_group->key.objectid)
10385 		fs_info->first_logical_byte = (u64)-1;
10386 	spin_unlock(&fs_info->block_group_cache_lock);
10387 
10388 	down_write(&block_group->space_info->groups_sem);
10389 	/*
10390 	 * we must use list_del_init so people can check to see if they
10391 	 * are still on the list after taking the semaphore
10392 	 */
10393 	list_del_init(&block_group->list);
10394 	if (list_empty(&block_group->space_info->block_groups[index])) {
10395 		kobj = block_group->space_info->block_group_kobjs[index];
10396 		block_group->space_info->block_group_kobjs[index] = NULL;
10397 		clear_avail_alloc_bits(fs_info, block_group->flags);
10398 	}
10399 	up_write(&block_group->space_info->groups_sem);
10400 	if (kobj) {
10401 		kobject_del(kobj);
10402 		kobject_put(kobj);
10403 	}
10404 
10405 	if (block_group->has_caching_ctl)
10406 		caching_ctl = get_caching_control(block_group);
10407 	if (block_group->cached == BTRFS_CACHE_STARTED)
10408 		wait_block_group_cache_done(block_group);
10409 	if (block_group->has_caching_ctl) {
10410 		down_write(&fs_info->commit_root_sem);
10411 		if (!caching_ctl) {
10412 			struct btrfs_caching_control *ctl;
10413 
10414 			list_for_each_entry(ctl,
10415 				    &fs_info->caching_block_groups, list)
10416 				if (ctl->block_group == block_group) {
10417 					caching_ctl = ctl;
10418 					atomic_inc(&caching_ctl->count);
10419 					break;
10420 				}
10421 		}
10422 		if (caching_ctl)
10423 			list_del_init(&caching_ctl->list);
10424 		up_write(&fs_info->commit_root_sem);
10425 		if (caching_ctl) {
10426 			/* Once for the caching bgs list and once for us. */
10427 			put_caching_control(caching_ctl);
10428 			put_caching_control(caching_ctl);
10429 		}
10430 	}
10431 
10432 	spin_lock(&trans->transaction->dirty_bgs_lock);
10433 	if (!list_empty(&block_group->dirty_list)) {
10434 		WARN_ON(1);
10435 	}
10436 	if (!list_empty(&block_group->io_list)) {
10437 		WARN_ON(1);
10438 	}
10439 	spin_unlock(&trans->transaction->dirty_bgs_lock);
10440 	btrfs_remove_free_space_cache(block_group);
10441 
10442 	spin_lock(&block_group->space_info->lock);
10443 	list_del_init(&block_group->ro_list);
10444 
10445 	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
10446 		WARN_ON(block_group->space_info->total_bytes
10447 			< block_group->key.offset);
10448 		WARN_ON(block_group->space_info->bytes_readonly
10449 			< block_group->key.offset);
10450 		WARN_ON(block_group->space_info->disk_total
10451 			< block_group->key.offset * factor);
10452 	}
10453 	block_group->space_info->total_bytes -= block_group->key.offset;
10454 	block_group->space_info->bytes_readonly -= block_group->key.offset;
10455 	block_group->space_info->disk_total -= block_group->key.offset * factor;
10456 
10457 	spin_unlock(&block_group->space_info->lock);
10458 
10459 	memcpy(&key, &block_group->key, sizeof(key));
10460 
10461 	mutex_lock(&fs_info->chunk_mutex);
10462 	if (!list_empty(&em->list)) {
10463 		/* We're in the transaction->pending_chunks list. */
10464 		free_extent_map(em);
10465 	}
10466 	spin_lock(&block_group->lock);
10467 	block_group->removed = 1;
10468 	/*
10469 	 * At this point trimming can't start on this block group, because we
10470 	 * removed the block group from the tree fs_info->block_group_cache_tree
10471 	 * so no one can't find it anymore and even if someone already got this
10472 	 * block group before we removed it from the rbtree, they have already
10473 	 * incremented block_group->trimming - if they didn't, they won't find
10474 	 * any free space entries because we already removed them all when we
10475 	 * called btrfs_remove_free_space_cache().
10476 	 *
10477 	 * And we must not remove the extent map from the fs_info->mapping_tree
10478 	 * to prevent the same logical address range and physical device space
10479 	 * ranges from being reused for a new block group. This is because our
10480 	 * fs trim operation (btrfs_trim_fs() / btrfs_ioctl_fitrim()) is
10481 	 * completely transactionless, so while it is trimming a range the
10482 	 * currently running transaction might finish and a new one start,
10483 	 * allowing for new block groups to be created that can reuse the same
10484 	 * physical device locations unless we take this special care.
10485 	 *
10486 	 * There may also be an implicit trim operation if the file system
10487 	 * is mounted with -odiscard. The same protections must remain
10488 	 * in place until the extents have been discarded completely when
10489 	 * the transaction commit has completed.
10490 	 */
10491 	remove_em = (atomic_read(&block_group->trimming) == 0);
10492 	/*
10493 	 * Make sure a trimmer task always sees the em in the pinned_chunks list
10494 	 * if it sees block_group->removed == 1 (needs to lock block_group->lock
10495 	 * before checking block_group->removed).
10496 	 */
10497 	if (!remove_em) {
10498 		/*
10499 		 * Our em might be in trans->transaction->pending_chunks which
10500 		 * is protected by fs_info->chunk_mutex ([lock|unlock]_chunks),
10501 		 * and so is the fs_info->pinned_chunks list.
10502 		 *
10503 		 * So at this point we must be holding the chunk_mutex to avoid
10504 		 * any races with chunk allocation (more specifically at
10505 		 * volumes.c:contains_pending_extent()), to ensure it always
10506 		 * sees the em, either in the pending_chunks list or in the
10507 		 * pinned_chunks list.
10508 		 */
10509 		list_move_tail(&em->list, &fs_info->pinned_chunks);
10510 	}
10511 	spin_unlock(&block_group->lock);
10512 
10513 	if (remove_em) {
10514 		struct extent_map_tree *em_tree;
10515 
10516 		em_tree = &fs_info->mapping_tree.map_tree;
10517 		write_lock(&em_tree->lock);
10518 		/*
10519 		 * The em might be in the pending_chunks list, so make sure the
10520 		 * chunk mutex is locked, since remove_extent_mapping() will
10521 		 * delete us from that list.
10522 		 */
10523 		remove_extent_mapping(em_tree, em);
10524 		write_unlock(&em_tree->lock);
10525 		/* once for the tree */
10526 		free_extent_map(em);
10527 	}
10528 
10529 	mutex_unlock(&fs_info->chunk_mutex);
10530 
10531 	ret = remove_block_group_free_space(trans, fs_info, block_group);
10532 	if (ret)
10533 		goto out;
10534 
10535 	btrfs_put_block_group(block_group);
10536 	btrfs_put_block_group(block_group);
10537 
10538 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
10539 	if (ret > 0)
10540 		ret = -EIO;
10541 	if (ret < 0)
10542 		goto out;
10543 
10544 	ret = btrfs_del_item(trans, root, path);
10545 out:
10546 	btrfs_free_path(path);
10547 	return ret;
10548 }
10549 
10550 struct btrfs_trans_handle *
10551 btrfs_start_trans_remove_block_group(struct btrfs_fs_info *fs_info,
10552 				     const u64 chunk_offset)
10553 {
10554 	struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
10555 	struct extent_map *em;
10556 	struct map_lookup *map;
10557 	unsigned int num_items;
10558 
10559 	read_lock(&em_tree->lock);
10560 	em = lookup_extent_mapping(em_tree, chunk_offset, 1);
10561 	read_unlock(&em_tree->lock);
10562 	ASSERT(em && em->start == chunk_offset);
10563 
10564 	/*
10565 	 * We need to reserve 3 + N units from the metadata space info in order
10566 	 * to remove a block group (done at btrfs_remove_chunk() and at
10567 	 * btrfs_remove_block_group()), which are used for:
10568 	 *
10569 	 * 1 unit for adding the free space inode's orphan (located in the tree
10570 	 * of tree roots).
10571 	 * 1 unit for deleting the block group item (located in the extent
10572 	 * tree).
10573 	 * 1 unit for deleting the free space item (located in tree of tree
10574 	 * roots).
10575 	 * N units for deleting N device extent items corresponding to each
10576 	 * stripe (located in the device tree).
10577 	 *
10578 	 * In order to remove a block group we also need to reserve units in the
10579 	 * system space info in order to update the chunk tree (update one or
10580 	 * more device items and remove one chunk item), but this is done at
10581 	 * btrfs_remove_chunk() through a call to check_system_chunk().
10582 	 */
10583 	map = em->map_lookup;
10584 	num_items = 3 + map->num_stripes;
10585 	free_extent_map(em);
10586 
10587 	return btrfs_start_transaction_fallback_global_rsv(fs_info->extent_root,
10588 							   num_items, 1);
10589 }
10590 
10591 /*
10592  * Process the unused_bgs list and remove any that don't have any allocated
10593  * space inside of them.
10594  */
10595 void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
10596 {
10597 	struct btrfs_block_group_cache *block_group;
10598 	struct btrfs_space_info *space_info;
10599 	struct btrfs_trans_handle *trans;
10600 	int ret = 0;
10601 
10602 	if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
10603 		return;
10604 
10605 	spin_lock(&fs_info->unused_bgs_lock);
10606 	while (!list_empty(&fs_info->unused_bgs)) {
10607 		u64 start, end;
10608 		int trimming;
10609 
10610 		block_group = list_first_entry(&fs_info->unused_bgs,
10611 					       struct btrfs_block_group_cache,
10612 					       bg_list);
10613 		list_del_init(&block_group->bg_list);
10614 
10615 		space_info = block_group->space_info;
10616 
10617 		if (ret || btrfs_mixed_space_info(space_info)) {
10618 			btrfs_put_block_group(block_group);
10619 			continue;
10620 		}
10621 		spin_unlock(&fs_info->unused_bgs_lock);
10622 
10623 		mutex_lock(&fs_info->delete_unused_bgs_mutex);
10624 
10625 		/* Don't want to race with allocators so take the groups_sem */
10626 		down_write(&space_info->groups_sem);
10627 		spin_lock(&block_group->lock);
10628 		if (block_group->reserved ||
10629 		    btrfs_block_group_used(&block_group->item) ||
10630 		    block_group->ro ||
10631 		    list_is_singular(&block_group->list)) {
10632 			/*
10633 			 * We want to bail if we made new allocations or have
10634 			 * outstanding allocations in this block group.  We do
10635 			 * the ro check in case balance is currently acting on
10636 			 * this block group.
10637 			 */
10638 			spin_unlock(&block_group->lock);
10639 			up_write(&space_info->groups_sem);
10640 			goto next;
10641 		}
10642 		spin_unlock(&block_group->lock);
10643 
10644 		/* We don't want to force the issue, only flip if it's ok. */
10645 		ret = inc_block_group_ro(block_group, 0);
10646 		up_write(&space_info->groups_sem);
10647 		if (ret < 0) {
10648 			ret = 0;
10649 			goto next;
10650 		}
10651 
10652 		/*
10653 		 * Want to do this before we do anything else so we can recover
10654 		 * properly if we fail to join the transaction.
10655 		 */
10656 		trans = btrfs_start_trans_remove_block_group(fs_info,
10657 						     block_group->key.objectid);
10658 		if (IS_ERR(trans)) {
10659 			btrfs_dec_block_group_ro(block_group);
10660 			ret = PTR_ERR(trans);
10661 			goto next;
10662 		}
10663 
10664 		/*
10665 		 * We could have pending pinned extents for this block group,
10666 		 * just delete them, we don't care about them anymore.
10667 		 */
10668 		start = block_group->key.objectid;
10669 		end = start + block_group->key.offset - 1;
10670 		/*
10671 		 * Hold the unused_bg_unpin_mutex lock to avoid racing with
10672 		 * btrfs_finish_extent_commit(). If we are at transaction N,
10673 		 * another task might be running finish_extent_commit() for the
10674 		 * previous transaction N - 1, and have seen a range belonging
10675 		 * to the block group in freed_extents[] before we were able to
10676 		 * clear the whole block group range from freed_extents[]. This
10677 		 * means that task can lookup for the block group after we
10678 		 * unpinned it from freed_extents[] and removed it, leading to
10679 		 * a BUG_ON() at btrfs_unpin_extent_range().
10680 		 */
10681 		mutex_lock(&fs_info->unused_bg_unpin_mutex);
10682 		ret = clear_extent_bits(&fs_info->freed_extents[0], start, end,
10683 				  EXTENT_DIRTY);
10684 		if (ret) {
10685 			mutex_unlock(&fs_info->unused_bg_unpin_mutex);
10686 			btrfs_dec_block_group_ro(block_group);
10687 			goto end_trans;
10688 		}
10689 		ret = clear_extent_bits(&fs_info->freed_extents[1], start, end,
10690 				  EXTENT_DIRTY);
10691 		if (ret) {
10692 			mutex_unlock(&fs_info->unused_bg_unpin_mutex);
10693 			btrfs_dec_block_group_ro(block_group);
10694 			goto end_trans;
10695 		}
10696 		mutex_unlock(&fs_info->unused_bg_unpin_mutex);
10697 
10698 		/* Reset pinned so btrfs_put_block_group doesn't complain */
10699 		spin_lock(&space_info->lock);
10700 		spin_lock(&block_group->lock);
10701 
10702 		space_info->bytes_pinned -= block_group->pinned;
10703 		space_info->bytes_readonly += block_group->pinned;
10704 		percpu_counter_add(&space_info->total_bytes_pinned,
10705 				   -block_group->pinned);
10706 		block_group->pinned = 0;
10707 
10708 		spin_unlock(&block_group->lock);
10709 		spin_unlock(&space_info->lock);
10710 
10711 		/* DISCARD can flip during remount */
10712 		trimming = btrfs_test_opt(fs_info, DISCARD);
10713 
10714 		/* Implicit trim during transaction commit. */
10715 		if (trimming)
10716 			btrfs_get_block_group_trimming(block_group);
10717 
10718 		/*
10719 		 * Btrfs_remove_chunk will abort the transaction if things go
10720 		 * horribly wrong.
10721 		 */
10722 		ret = btrfs_remove_chunk(trans, fs_info,
10723 					 block_group->key.objectid);
10724 
10725 		if (ret) {
10726 			if (trimming)
10727 				btrfs_put_block_group_trimming(block_group);
10728 			goto end_trans;
10729 		}
10730 
10731 		/*
10732 		 * If we're not mounted with -odiscard, we can just forget
10733 		 * about this block group. Otherwise we'll need to wait
10734 		 * until transaction commit to do the actual discard.
10735 		 */
10736 		if (trimming) {
10737 			spin_lock(&fs_info->unused_bgs_lock);
10738 			/*
10739 			 * A concurrent scrub might have added us to the list
10740 			 * fs_info->unused_bgs, so use a list_move operation
10741 			 * to add the block group to the deleted_bgs list.
10742 			 */
10743 			list_move(&block_group->bg_list,
10744 				  &trans->transaction->deleted_bgs);
10745 			spin_unlock(&fs_info->unused_bgs_lock);
10746 			btrfs_get_block_group(block_group);
10747 		}
10748 end_trans:
10749 		btrfs_end_transaction(trans);
10750 next:
10751 		mutex_unlock(&fs_info->delete_unused_bgs_mutex);
10752 		btrfs_put_block_group(block_group);
10753 		spin_lock(&fs_info->unused_bgs_lock);
10754 	}
10755 	spin_unlock(&fs_info->unused_bgs_lock);
10756 }
10757 
10758 int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
10759 {
10760 	struct btrfs_space_info *space_info;
10761 	struct btrfs_super_block *disk_super;
10762 	u64 features;
10763 	u64 flags;
10764 	int mixed = 0;
10765 	int ret;
10766 
10767 	disk_super = fs_info->super_copy;
10768 	if (!btrfs_super_root(disk_super))
10769 		return -EINVAL;
10770 
10771 	features = btrfs_super_incompat_flags(disk_super);
10772 	if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
10773 		mixed = 1;
10774 
10775 	flags = BTRFS_BLOCK_GROUP_SYSTEM;
10776 	ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
10777 	if (ret)
10778 		goto out;
10779 
10780 	if (mixed) {
10781 		flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
10782 		ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
10783 	} else {
10784 		flags = BTRFS_BLOCK_GROUP_METADATA;
10785 		ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
10786 		if (ret)
10787 			goto out;
10788 
10789 		flags = BTRFS_BLOCK_GROUP_DATA;
10790 		ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
10791 	}
10792 out:
10793 	return ret;
10794 }
10795 
10796 int btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info,
10797 				   u64 start, u64 end)
10798 {
10799 	return unpin_extent_range(fs_info, start, end, false);
10800 }
10801 
10802 /*
10803  * It used to be that old block groups would be left around forever.
10804  * Iterating over them would be enough to trim unused space.  Since we
10805  * now automatically remove them, we also need to iterate over unallocated
10806  * space.
10807  *
10808  * We don't want a transaction for this since the discard may take a
10809  * substantial amount of time.  We don't require that a transaction be
10810  * running, but we do need to take a running transaction into account
10811  * to ensure that we're not discarding chunks that were released in
10812  * the current transaction.
10813  *
10814  * Holding the chunks lock will prevent other threads from allocating
10815  * or releasing chunks, but it won't prevent a running transaction
10816  * from committing and releasing the memory that the pending chunks
10817  * list head uses.  For that, we need to take a reference to the
10818  * transaction.
10819  */
10820 static int btrfs_trim_free_extents(struct btrfs_device *device,
10821 				   u64 minlen, u64 *trimmed)
10822 {
10823 	u64 start = 0, len = 0;
10824 	int ret;
10825 
10826 	*trimmed = 0;
10827 
10828 	/* Not writeable = nothing to do. */
10829 	if (!device->writeable)
10830 		return 0;
10831 
10832 	/* No free space = nothing to do. */
10833 	if (device->total_bytes <= device->bytes_used)
10834 		return 0;
10835 
10836 	ret = 0;
10837 
10838 	while (1) {
10839 		struct btrfs_fs_info *fs_info = device->fs_info;
10840 		struct btrfs_transaction *trans;
10841 		u64 bytes;
10842 
10843 		ret = mutex_lock_interruptible(&fs_info->chunk_mutex);
10844 		if (ret)
10845 			return ret;
10846 
10847 		down_read(&fs_info->commit_root_sem);
10848 
10849 		spin_lock(&fs_info->trans_lock);
10850 		trans = fs_info->running_transaction;
10851 		if (trans)
10852 			atomic_inc(&trans->use_count);
10853 		spin_unlock(&fs_info->trans_lock);
10854 
10855 		ret = find_free_dev_extent_start(trans, device, minlen, start,
10856 						 &start, &len);
10857 		if (trans)
10858 			btrfs_put_transaction(trans);
10859 
10860 		if (ret) {
10861 			up_read(&fs_info->commit_root_sem);
10862 			mutex_unlock(&fs_info->chunk_mutex);
10863 			if (ret == -ENOSPC)
10864 				ret = 0;
10865 			break;
10866 		}
10867 
10868 		ret = btrfs_issue_discard(device->bdev, start, len, &bytes);
10869 		up_read(&fs_info->commit_root_sem);
10870 		mutex_unlock(&fs_info->chunk_mutex);
10871 
10872 		if (ret)
10873 			break;
10874 
10875 		start += len;
10876 		*trimmed += bytes;
10877 
10878 		if (fatal_signal_pending(current)) {
10879 			ret = -ERESTARTSYS;
10880 			break;
10881 		}
10882 
10883 		cond_resched();
10884 	}
10885 
10886 	return ret;
10887 }
10888 
10889 int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
10890 {
10891 	struct btrfs_block_group_cache *cache = NULL;
10892 	struct btrfs_device *device;
10893 	struct list_head *devices;
10894 	u64 group_trimmed;
10895 	u64 start;
10896 	u64 end;
10897 	u64 trimmed = 0;
10898 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
10899 	int ret = 0;
10900 
10901 	/*
10902 	 * try to trim all FS space, our block group may start from non-zero.
10903 	 */
10904 	if (range->len == total_bytes)
10905 		cache = btrfs_lookup_first_block_group(fs_info, range->start);
10906 	else
10907 		cache = btrfs_lookup_block_group(fs_info, range->start);
10908 
10909 	while (cache) {
10910 		if (cache->key.objectid >= (range->start + range->len)) {
10911 			btrfs_put_block_group(cache);
10912 			break;
10913 		}
10914 
10915 		start = max(range->start, cache->key.objectid);
10916 		end = min(range->start + range->len,
10917 				cache->key.objectid + cache->key.offset);
10918 
10919 		if (end - start >= range->minlen) {
10920 			if (!block_group_cache_done(cache)) {
10921 				ret = cache_block_group(cache, 0);
10922 				if (ret) {
10923 					btrfs_put_block_group(cache);
10924 					break;
10925 				}
10926 				ret = wait_block_group_cache_done(cache);
10927 				if (ret) {
10928 					btrfs_put_block_group(cache);
10929 					break;
10930 				}
10931 			}
10932 			ret = btrfs_trim_block_group(cache,
10933 						     &group_trimmed,
10934 						     start,
10935 						     end,
10936 						     range->minlen);
10937 
10938 			trimmed += group_trimmed;
10939 			if (ret) {
10940 				btrfs_put_block_group(cache);
10941 				break;
10942 			}
10943 		}
10944 
10945 		cache = next_block_group(fs_info, cache);
10946 	}
10947 
10948 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
10949 	devices = &fs_info->fs_devices->alloc_list;
10950 	list_for_each_entry(device, devices, dev_alloc_list) {
10951 		ret = btrfs_trim_free_extents(device, range->minlen,
10952 					      &group_trimmed);
10953 		if (ret)
10954 			break;
10955 
10956 		trimmed += group_trimmed;
10957 	}
10958 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
10959 
10960 	range->len = trimmed;
10961 	return ret;
10962 }
10963 
10964 /*
10965  * btrfs_{start,end}_write_no_snapshoting() are similar to
10966  * mnt_{want,drop}_write(), they are used to prevent some tasks from writing
10967  * data into the page cache through nocow before the subvolume is snapshoted,
10968  * but flush the data into disk after the snapshot creation, or to prevent
10969  * operations while snapshoting is ongoing and that cause the snapshot to be
10970  * inconsistent (writes followed by expanding truncates for example).
10971  */
10972 void btrfs_end_write_no_snapshoting(struct btrfs_root *root)
10973 {
10974 	percpu_counter_dec(&root->subv_writers->counter);
10975 	/*
10976 	 * Make sure counter is updated before we wake up waiters.
10977 	 */
10978 	smp_mb();
10979 	if (waitqueue_active(&root->subv_writers->wait))
10980 		wake_up(&root->subv_writers->wait);
10981 }
10982 
10983 int btrfs_start_write_no_snapshoting(struct btrfs_root *root)
10984 {
10985 	if (atomic_read(&root->will_be_snapshoted))
10986 		return 0;
10987 
10988 	percpu_counter_inc(&root->subv_writers->counter);
10989 	/*
10990 	 * Make sure counter is updated before we check for snapshot creation.
10991 	 */
10992 	smp_mb();
10993 	if (atomic_read(&root->will_be_snapshoted)) {
10994 		btrfs_end_write_no_snapshoting(root);
10995 		return 0;
10996 	}
10997 	return 1;
10998 }
10999 
11000 static int wait_snapshoting_atomic_t(atomic_t *a)
11001 {
11002 	schedule();
11003 	return 0;
11004 }
11005 
11006 void btrfs_wait_for_snapshot_creation(struct btrfs_root *root)
11007 {
11008 	while (true) {
11009 		int ret;
11010 
11011 		ret = btrfs_start_write_no_snapshoting(root);
11012 		if (ret)
11013 			break;
11014 		wait_on_atomic_t(&root->will_be_snapshoted,
11015 				 wait_snapshoting_atomic_t,
11016 				 TASK_UNINTERRUPTIBLE);
11017 	}
11018 }
11019