xref: /openbmc/linux/fs/btrfs/extent-tree.c (revision ee7da21a)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5 
6 #include <linux/sched.h>
7 #include <linux/sched/signal.h>
8 #include <linux/pagemap.h>
9 #include <linux/writeback.h>
10 #include <linux/blkdev.h>
11 #include <linux/sort.h>
12 #include <linux/rcupdate.h>
13 #include <linux/kthread.h>
14 #include <linux/slab.h>
15 #include <linux/ratelimit.h>
16 #include <linux/percpu_counter.h>
17 #include <linux/lockdep.h>
18 #include <linux/crc32c.h>
19 #include "misc.h"
20 #include "tree-log.h"
21 #include "disk-io.h"
22 #include "print-tree.h"
23 #include "volumes.h"
24 #include "raid56.h"
25 #include "locking.h"
26 #include "free-space-cache.h"
27 #include "free-space-tree.h"
28 #include "sysfs.h"
29 #include "qgroup.h"
30 #include "ref-verify.h"
31 #include "space-info.h"
32 #include "block-rsv.h"
33 #include "delalloc-space.h"
34 #include "block-group.h"
35 #include "discard.h"
36 #include "rcu-string.h"
37 #include "zoned.h"
38 #include "dev-replace.h"
39 
40 #undef SCRAMBLE_DELAYED_REFS
41 
42 
43 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
44 			       struct btrfs_delayed_ref_node *node, u64 parent,
45 			       u64 root_objectid, u64 owner_objectid,
46 			       u64 owner_offset, int refs_to_drop,
47 			       struct btrfs_delayed_extent_op *extra_op);
48 static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
49 				    struct extent_buffer *leaf,
50 				    struct btrfs_extent_item *ei);
51 static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
52 				      u64 parent, u64 root_objectid,
53 				      u64 flags, u64 owner, u64 offset,
54 				      struct btrfs_key *ins, int ref_mod);
55 static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
56 				     struct btrfs_delayed_ref_node *node,
57 				     struct btrfs_delayed_extent_op *extent_op);
58 static int find_next_key(struct btrfs_path *path, int level,
59 			 struct btrfs_key *key);
60 
61 static int block_group_bits(struct btrfs_block_group *cache, u64 bits)
62 {
63 	return (cache->flags & bits) == bits;
64 }
65 
66 int btrfs_add_excluded_extent(struct btrfs_fs_info *fs_info,
67 			      u64 start, u64 num_bytes)
68 {
69 	u64 end = start + num_bytes - 1;
70 	set_extent_bits(&fs_info->excluded_extents, start, end,
71 			EXTENT_UPTODATE);
72 	return 0;
73 }
74 
75 void btrfs_free_excluded_extents(struct btrfs_block_group *cache)
76 {
77 	struct btrfs_fs_info *fs_info = cache->fs_info;
78 	u64 start, end;
79 
80 	start = cache->start;
81 	end = start + cache->length - 1;
82 
83 	clear_extent_bits(&fs_info->excluded_extents, start, end,
84 			  EXTENT_UPTODATE);
85 }
86 
87 /* simple helper to search for an existing data extent at a given offset */
88 int btrfs_lookup_data_extent(struct btrfs_fs_info *fs_info, u64 start, u64 len)
89 {
90 	int ret;
91 	struct btrfs_key key;
92 	struct btrfs_path *path;
93 
94 	path = btrfs_alloc_path();
95 	if (!path)
96 		return -ENOMEM;
97 
98 	key.objectid = start;
99 	key.offset = len;
100 	key.type = BTRFS_EXTENT_ITEM_KEY;
101 	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
102 	btrfs_free_path(path);
103 	return ret;
104 }
105 
106 /*
107  * helper function to lookup reference count and flags of a tree block.
108  *
109  * the head node for delayed ref is used to store the sum of all the
110  * reference count modifications queued up in the rbtree. the head
111  * node may also store the extent flags to set. This way you can check
112  * to see what the reference count and extent flags would be if all of
113  * the delayed refs are not processed.
114  */
115 int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
116 			     struct btrfs_fs_info *fs_info, u64 bytenr,
117 			     u64 offset, int metadata, u64 *refs, u64 *flags)
118 {
119 	struct btrfs_delayed_ref_head *head;
120 	struct btrfs_delayed_ref_root *delayed_refs;
121 	struct btrfs_path *path;
122 	struct btrfs_extent_item *ei;
123 	struct extent_buffer *leaf;
124 	struct btrfs_key key;
125 	u32 item_size;
126 	u64 num_refs;
127 	u64 extent_flags;
128 	int ret;
129 
130 	/*
131 	 * If we don't have skinny metadata, don't bother doing anything
132 	 * different
133 	 */
134 	if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA)) {
135 		offset = fs_info->nodesize;
136 		metadata = 0;
137 	}
138 
139 	path = btrfs_alloc_path();
140 	if (!path)
141 		return -ENOMEM;
142 
143 	if (!trans) {
144 		path->skip_locking = 1;
145 		path->search_commit_root = 1;
146 	}
147 
148 search_again:
149 	key.objectid = bytenr;
150 	key.offset = offset;
151 	if (metadata)
152 		key.type = BTRFS_METADATA_ITEM_KEY;
153 	else
154 		key.type = BTRFS_EXTENT_ITEM_KEY;
155 
156 	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
157 	if (ret < 0)
158 		goto out_free;
159 
160 	if (ret > 0 && metadata && key.type == BTRFS_METADATA_ITEM_KEY) {
161 		if (path->slots[0]) {
162 			path->slots[0]--;
163 			btrfs_item_key_to_cpu(path->nodes[0], &key,
164 					      path->slots[0]);
165 			if (key.objectid == bytenr &&
166 			    key.type == BTRFS_EXTENT_ITEM_KEY &&
167 			    key.offset == fs_info->nodesize)
168 				ret = 0;
169 		}
170 	}
171 
172 	if (ret == 0) {
173 		leaf = path->nodes[0];
174 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
175 		if (item_size >= sizeof(*ei)) {
176 			ei = btrfs_item_ptr(leaf, path->slots[0],
177 					    struct btrfs_extent_item);
178 			num_refs = btrfs_extent_refs(leaf, ei);
179 			extent_flags = btrfs_extent_flags(leaf, ei);
180 		} else {
181 			ret = -EINVAL;
182 			btrfs_print_v0_err(fs_info);
183 			if (trans)
184 				btrfs_abort_transaction(trans, ret);
185 			else
186 				btrfs_handle_fs_error(fs_info, ret, NULL);
187 
188 			goto out_free;
189 		}
190 
191 		BUG_ON(num_refs == 0);
192 	} else {
193 		num_refs = 0;
194 		extent_flags = 0;
195 		ret = 0;
196 	}
197 
198 	if (!trans)
199 		goto out;
200 
201 	delayed_refs = &trans->transaction->delayed_refs;
202 	spin_lock(&delayed_refs->lock);
203 	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
204 	if (head) {
205 		if (!mutex_trylock(&head->mutex)) {
206 			refcount_inc(&head->refs);
207 			spin_unlock(&delayed_refs->lock);
208 
209 			btrfs_release_path(path);
210 
211 			/*
212 			 * Mutex was contended, block until it's released and try
213 			 * again
214 			 */
215 			mutex_lock(&head->mutex);
216 			mutex_unlock(&head->mutex);
217 			btrfs_put_delayed_ref_head(head);
218 			goto search_again;
219 		}
220 		spin_lock(&head->lock);
221 		if (head->extent_op && head->extent_op->update_flags)
222 			extent_flags |= head->extent_op->flags_to_set;
223 		else
224 			BUG_ON(num_refs == 0);
225 
226 		num_refs += head->ref_mod;
227 		spin_unlock(&head->lock);
228 		mutex_unlock(&head->mutex);
229 	}
230 	spin_unlock(&delayed_refs->lock);
231 out:
232 	WARN_ON(num_refs == 0);
233 	if (refs)
234 		*refs = num_refs;
235 	if (flags)
236 		*flags = extent_flags;
237 out_free:
238 	btrfs_free_path(path);
239 	return ret;
240 }
241 
242 /*
243  * Back reference rules.  Back refs have three main goals:
244  *
245  * 1) differentiate between all holders of references to an extent so that
246  *    when a reference is dropped we can make sure it was a valid reference
247  *    before freeing the extent.
248  *
249  * 2) Provide enough information to quickly find the holders of an extent
250  *    if we notice a given block is corrupted or bad.
251  *
252  * 3) Make it easy to migrate blocks for FS shrinking or storage pool
253  *    maintenance.  This is actually the same as #2, but with a slightly
254  *    different use case.
255  *
256  * There are two kinds of back refs. The implicit back refs is optimized
257  * for pointers in non-shared tree blocks. For a given pointer in a block,
258  * back refs of this kind provide information about the block's owner tree
259  * and the pointer's key. These information allow us to find the block by
260  * b-tree searching. The full back refs is for pointers in tree blocks not
261  * referenced by their owner trees. The location of tree block is recorded
262  * in the back refs. Actually the full back refs is generic, and can be
263  * used in all cases the implicit back refs is used. The major shortcoming
264  * of the full back refs is its overhead. Every time a tree block gets
265  * COWed, we have to update back refs entry for all pointers in it.
266  *
267  * For a newly allocated tree block, we use implicit back refs for
268  * pointers in it. This means most tree related operations only involve
269  * implicit back refs. For a tree block created in old transaction, the
270  * only way to drop a reference to it is COW it. So we can detect the
271  * event that tree block loses its owner tree's reference and do the
272  * back refs conversion.
273  *
274  * When a tree block is COWed through a tree, there are four cases:
275  *
276  * The reference count of the block is one and the tree is the block's
277  * owner tree. Nothing to do in this case.
278  *
279  * The reference count of the block is one and the tree is not the
280  * block's owner tree. In this case, full back refs is used for pointers
281  * in the block. Remove these full back refs, add implicit back refs for
282  * every pointers in the new block.
283  *
284  * The reference count of the block is greater than one and the tree is
285  * the block's owner tree. In this case, implicit back refs is used for
286  * pointers in the block. Add full back refs for every pointers in the
287  * block, increase lower level extents' reference counts. The original
288  * implicit back refs are entailed to the new block.
289  *
290  * The reference count of the block is greater than one and the tree is
291  * not the block's owner tree. Add implicit back refs for every pointer in
292  * the new block, increase lower level extents' reference count.
293  *
294  * Back Reference Key composing:
295  *
296  * The key objectid corresponds to the first byte in the extent,
297  * The key type is used to differentiate between types of back refs.
298  * There are different meanings of the key offset for different types
299  * of back refs.
300  *
301  * File extents can be referenced by:
302  *
303  * - multiple snapshots, subvolumes, or different generations in one subvol
304  * - different files inside a single subvolume
305  * - different offsets inside a file (bookend extents in file.c)
306  *
307  * The extent ref structure for the implicit back refs has fields for:
308  *
309  * - Objectid of the subvolume root
310  * - objectid of the file holding the reference
311  * - original offset in the file
312  * - how many bookend extents
313  *
314  * The key offset for the implicit back refs is hash of the first
315  * three fields.
316  *
317  * The extent ref structure for the full back refs has field for:
318  *
319  * - number of pointers in the tree leaf
320  *
321  * The key offset for the implicit back refs is the first byte of
322  * the tree leaf
323  *
324  * When a file extent is allocated, The implicit back refs is used.
325  * the fields are filled in:
326  *
327  *     (root_key.objectid, inode objectid, offset in file, 1)
328  *
329  * When a file extent is removed file truncation, we find the
330  * corresponding implicit back refs and check the following fields:
331  *
332  *     (btrfs_header_owner(leaf), inode objectid, offset in file)
333  *
334  * Btree extents can be referenced by:
335  *
336  * - Different subvolumes
337  *
338  * Both the implicit back refs and the full back refs for tree blocks
339  * only consist of key. The key offset for the implicit back refs is
340  * objectid of block's owner tree. The key offset for the full back refs
341  * is the first byte of parent block.
342  *
343  * When implicit back refs is used, information about the lowest key and
344  * level of the tree block are required. These information are stored in
345  * tree block info structure.
346  */
347 
348 /*
349  * is_data == BTRFS_REF_TYPE_BLOCK, tree block type is required,
350  * is_data == BTRFS_REF_TYPE_DATA, data type is requiried,
351  * is_data == BTRFS_REF_TYPE_ANY, either type is OK.
352  */
353 int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb,
354 				     struct btrfs_extent_inline_ref *iref,
355 				     enum btrfs_inline_ref_type is_data)
356 {
357 	int type = btrfs_extent_inline_ref_type(eb, iref);
358 	u64 offset = btrfs_extent_inline_ref_offset(eb, iref);
359 
360 	if (type == BTRFS_TREE_BLOCK_REF_KEY ||
361 	    type == BTRFS_SHARED_BLOCK_REF_KEY ||
362 	    type == BTRFS_SHARED_DATA_REF_KEY ||
363 	    type == BTRFS_EXTENT_DATA_REF_KEY) {
364 		if (is_data == BTRFS_REF_TYPE_BLOCK) {
365 			if (type == BTRFS_TREE_BLOCK_REF_KEY)
366 				return type;
367 			if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
368 				ASSERT(eb->fs_info);
369 				/*
370 				 * Every shared one has parent tree block,
371 				 * which must be aligned to sector size.
372 				 */
373 				if (offset &&
374 				    IS_ALIGNED(offset, eb->fs_info->sectorsize))
375 					return type;
376 			}
377 		} else if (is_data == BTRFS_REF_TYPE_DATA) {
378 			if (type == BTRFS_EXTENT_DATA_REF_KEY)
379 				return type;
380 			if (type == BTRFS_SHARED_DATA_REF_KEY) {
381 				ASSERT(eb->fs_info);
382 				/*
383 				 * Every shared one has parent tree block,
384 				 * which must be aligned to sector size.
385 				 */
386 				if (offset &&
387 				    IS_ALIGNED(offset, eb->fs_info->sectorsize))
388 					return type;
389 			}
390 		} else {
391 			ASSERT(is_data == BTRFS_REF_TYPE_ANY);
392 			return type;
393 		}
394 	}
395 
396 	btrfs_print_leaf((struct extent_buffer *)eb);
397 	btrfs_err(eb->fs_info,
398 		  "eb %llu iref 0x%lx invalid extent inline ref type %d",
399 		  eb->start, (unsigned long)iref, type);
400 	WARN_ON(1);
401 
402 	return BTRFS_REF_TYPE_INVALID;
403 }
404 
405 u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset)
406 {
407 	u32 high_crc = ~(u32)0;
408 	u32 low_crc = ~(u32)0;
409 	__le64 lenum;
410 
411 	lenum = cpu_to_le64(root_objectid);
412 	high_crc = btrfs_crc32c(high_crc, &lenum, sizeof(lenum));
413 	lenum = cpu_to_le64(owner);
414 	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
415 	lenum = cpu_to_le64(offset);
416 	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
417 
418 	return ((u64)high_crc << 31) ^ (u64)low_crc;
419 }
420 
421 static u64 hash_extent_data_ref_item(struct extent_buffer *leaf,
422 				     struct btrfs_extent_data_ref *ref)
423 {
424 	return hash_extent_data_ref(btrfs_extent_data_ref_root(leaf, ref),
425 				    btrfs_extent_data_ref_objectid(leaf, ref),
426 				    btrfs_extent_data_ref_offset(leaf, ref));
427 }
428 
429 static int match_extent_data_ref(struct extent_buffer *leaf,
430 				 struct btrfs_extent_data_ref *ref,
431 				 u64 root_objectid, u64 owner, u64 offset)
432 {
433 	if (btrfs_extent_data_ref_root(leaf, ref) != root_objectid ||
434 	    btrfs_extent_data_ref_objectid(leaf, ref) != owner ||
435 	    btrfs_extent_data_ref_offset(leaf, ref) != offset)
436 		return 0;
437 	return 1;
438 }
439 
440 static noinline int lookup_extent_data_ref(struct btrfs_trans_handle *trans,
441 					   struct btrfs_path *path,
442 					   u64 bytenr, u64 parent,
443 					   u64 root_objectid,
444 					   u64 owner, u64 offset)
445 {
446 	struct btrfs_root *root = trans->fs_info->extent_root;
447 	struct btrfs_key key;
448 	struct btrfs_extent_data_ref *ref;
449 	struct extent_buffer *leaf;
450 	u32 nritems;
451 	int ret;
452 	int recow;
453 	int err = -ENOENT;
454 
455 	key.objectid = bytenr;
456 	if (parent) {
457 		key.type = BTRFS_SHARED_DATA_REF_KEY;
458 		key.offset = parent;
459 	} else {
460 		key.type = BTRFS_EXTENT_DATA_REF_KEY;
461 		key.offset = hash_extent_data_ref(root_objectid,
462 						  owner, offset);
463 	}
464 again:
465 	recow = 0;
466 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
467 	if (ret < 0) {
468 		err = ret;
469 		goto fail;
470 	}
471 
472 	if (parent) {
473 		if (!ret)
474 			return 0;
475 		goto fail;
476 	}
477 
478 	leaf = path->nodes[0];
479 	nritems = btrfs_header_nritems(leaf);
480 	while (1) {
481 		if (path->slots[0] >= nritems) {
482 			ret = btrfs_next_leaf(root, path);
483 			if (ret < 0)
484 				err = ret;
485 			if (ret)
486 				goto fail;
487 
488 			leaf = path->nodes[0];
489 			nritems = btrfs_header_nritems(leaf);
490 			recow = 1;
491 		}
492 
493 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
494 		if (key.objectid != bytenr ||
495 		    key.type != BTRFS_EXTENT_DATA_REF_KEY)
496 			goto fail;
497 
498 		ref = btrfs_item_ptr(leaf, path->slots[0],
499 				     struct btrfs_extent_data_ref);
500 
501 		if (match_extent_data_ref(leaf, ref, root_objectid,
502 					  owner, offset)) {
503 			if (recow) {
504 				btrfs_release_path(path);
505 				goto again;
506 			}
507 			err = 0;
508 			break;
509 		}
510 		path->slots[0]++;
511 	}
512 fail:
513 	return err;
514 }
515 
516 static noinline int insert_extent_data_ref(struct btrfs_trans_handle *trans,
517 					   struct btrfs_path *path,
518 					   u64 bytenr, u64 parent,
519 					   u64 root_objectid, u64 owner,
520 					   u64 offset, int refs_to_add)
521 {
522 	struct btrfs_root *root = trans->fs_info->extent_root;
523 	struct btrfs_key key;
524 	struct extent_buffer *leaf;
525 	u32 size;
526 	u32 num_refs;
527 	int ret;
528 
529 	key.objectid = bytenr;
530 	if (parent) {
531 		key.type = BTRFS_SHARED_DATA_REF_KEY;
532 		key.offset = parent;
533 		size = sizeof(struct btrfs_shared_data_ref);
534 	} else {
535 		key.type = BTRFS_EXTENT_DATA_REF_KEY;
536 		key.offset = hash_extent_data_ref(root_objectid,
537 						  owner, offset);
538 		size = sizeof(struct btrfs_extent_data_ref);
539 	}
540 
541 	ret = btrfs_insert_empty_item(trans, root, path, &key, size);
542 	if (ret && ret != -EEXIST)
543 		goto fail;
544 
545 	leaf = path->nodes[0];
546 	if (parent) {
547 		struct btrfs_shared_data_ref *ref;
548 		ref = btrfs_item_ptr(leaf, path->slots[0],
549 				     struct btrfs_shared_data_ref);
550 		if (ret == 0) {
551 			btrfs_set_shared_data_ref_count(leaf, ref, refs_to_add);
552 		} else {
553 			num_refs = btrfs_shared_data_ref_count(leaf, ref);
554 			num_refs += refs_to_add;
555 			btrfs_set_shared_data_ref_count(leaf, ref, num_refs);
556 		}
557 	} else {
558 		struct btrfs_extent_data_ref *ref;
559 		while (ret == -EEXIST) {
560 			ref = btrfs_item_ptr(leaf, path->slots[0],
561 					     struct btrfs_extent_data_ref);
562 			if (match_extent_data_ref(leaf, ref, root_objectid,
563 						  owner, offset))
564 				break;
565 			btrfs_release_path(path);
566 			key.offset++;
567 			ret = btrfs_insert_empty_item(trans, root, path, &key,
568 						      size);
569 			if (ret && ret != -EEXIST)
570 				goto fail;
571 
572 			leaf = path->nodes[0];
573 		}
574 		ref = btrfs_item_ptr(leaf, path->slots[0],
575 				     struct btrfs_extent_data_ref);
576 		if (ret == 0) {
577 			btrfs_set_extent_data_ref_root(leaf, ref,
578 						       root_objectid);
579 			btrfs_set_extent_data_ref_objectid(leaf, ref, owner);
580 			btrfs_set_extent_data_ref_offset(leaf, ref, offset);
581 			btrfs_set_extent_data_ref_count(leaf, ref, refs_to_add);
582 		} else {
583 			num_refs = btrfs_extent_data_ref_count(leaf, ref);
584 			num_refs += refs_to_add;
585 			btrfs_set_extent_data_ref_count(leaf, ref, num_refs);
586 		}
587 	}
588 	btrfs_mark_buffer_dirty(leaf);
589 	ret = 0;
590 fail:
591 	btrfs_release_path(path);
592 	return ret;
593 }
594 
595 static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
596 					   struct btrfs_path *path,
597 					   int refs_to_drop, int *last_ref)
598 {
599 	struct btrfs_key key;
600 	struct btrfs_extent_data_ref *ref1 = NULL;
601 	struct btrfs_shared_data_ref *ref2 = NULL;
602 	struct extent_buffer *leaf;
603 	u32 num_refs = 0;
604 	int ret = 0;
605 
606 	leaf = path->nodes[0];
607 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
608 
609 	if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
610 		ref1 = btrfs_item_ptr(leaf, path->slots[0],
611 				      struct btrfs_extent_data_ref);
612 		num_refs = btrfs_extent_data_ref_count(leaf, ref1);
613 	} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
614 		ref2 = btrfs_item_ptr(leaf, path->slots[0],
615 				      struct btrfs_shared_data_ref);
616 		num_refs = btrfs_shared_data_ref_count(leaf, ref2);
617 	} else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
618 		btrfs_print_v0_err(trans->fs_info);
619 		btrfs_abort_transaction(trans, -EINVAL);
620 		return -EINVAL;
621 	} else {
622 		BUG();
623 	}
624 
625 	BUG_ON(num_refs < refs_to_drop);
626 	num_refs -= refs_to_drop;
627 
628 	if (num_refs == 0) {
629 		ret = btrfs_del_item(trans, trans->fs_info->extent_root, path);
630 		*last_ref = 1;
631 	} else {
632 		if (key.type == BTRFS_EXTENT_DATA_REF_KEY)
633 			btrfs_set_extent_data_ref_count(leaf, ref1, num_refs);
634 		else if (key.type == BTRFS_SHARED_DATA_REF_KEY)
635 			btrfs_set_shared_data_ref_count(leaf, ref2, num_refs);
636 		btrfs_mark_buffer_dirty(leaf);
637 	}
638 	return ret;
639 }
640 
641 static noinline u32 extent_data_ref_count(struct btrfs_path *path,
642 					  struct btrfs_extent_inline_ref *iref)
643 {
644 	struct btrfs_key key;
645 	struct extent_buffer *leaf;
646 	struct btrfs_extent_data_ref *ref1;
647 	struct btrfs_shared_data_ref *ref2;
648 	u32 num_refs = 0;
649 	int type;
650 
651 	leaf = path->nodes[0];
652 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
653 
654 	BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
655 	if (iref) {
656 		/*
657 		 * If type is invalid, we should have bailed out earlier than
658 		 * this call.
659 		 */
660 		type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_DATA);
661 		ASSERT(type != BTRFS_REF_TYPE_INVALID);
662 		if (type == BTRFS_EXTENT_DATA_REF_KEY) {
663 			ref1 = (struct btrfs_extent_data_ref *)(&iref->offset);
664 			num_refs = btrfs_extent_data_ref_count(leaf, ref1);
665 		} else {
666 			ref2 = (struct btrfs_shared_data_ref *)(iref + 1);
667 			num_refs = btrfs_shared_data_ref_count(leaf, ref2);
668 		}
669 	} else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
670 		ref1 = btrfs_item_ptr(leaf, path->slots[0],
671 				      struct btrfs_extent_data_ref);
672 		num_refs = btrfs_extent_data_ref_count(leaf, ref1);
673 	} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
674 		ref2 = btrfs_item_ptr(leaf, path->slots[0],
675 				      struct btrfs_shared_data_ref);
676 		num_refs = btrfs_shared_data_ref_count(leaf, ref2);
677 	} else {
678 		WARN_ON(1);
679 	}
680 	return num_refs;
681 }
682 
683 static noinline int lookup_tree_block_ref(struct btrfs_trans_handle *trans,
684 					  struct btrfs_path *path,
685 					  u64 bytenr, u64 parent,
686 					  u64 root_objectid)
687 {
688 	struct btrfs_root *root = trans->fs_info->extent_root;
689 	struct btrfs_key key;
690 	int ret;
691 
692 	key.objectid = bytenr;
693 	if (parent) {
694 		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
695 		key.offset = parent;
696 	} else {
697 		key.type = BTRFS_TREE_BLOCK_REF_KEY;
698 		key.offset = root_objectid;
699 	}
700 
701 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
702 	if (ret > 0)
703 		ret = -ENOENT;
704 	return ret;
705 }
706 
707 static noinline int insert_tree_block_ref(struct btrfs_trans_handle *trans,
708 					  struct btrfs_path *path,
709 					  u64 bytenr, u64 parent,
710 					  u64 root_objectid)
711 {
712 	struct btrfs_key key;
713 	int ret;
714 
715 	key.objectid = bytenr;
716 	if (parent) {
717 		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
718 		key.offset = parent;
719 	} else {
720 		key.type = BTRFS_TREE_BLOCK_REF_KEY;
721 		key.offset = root_objectid;
722 	}
723 
724 	ret = btrfs_insert_empty_item(trans, trans->fs_info->extent_root,
725 				      path, &key, 0);
726 	btrfs_release_path(path);
727 	return ret;
728 }
729 
730 static inline int extent_ref_type(u64 parent, u64 owner)
731 {
732 	int type;
733 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
734 		if (parent > 0)
735 			type = BTRFS_SHARED_BLOCK_REF_KEY;
736 		else
737 			type = BTRFS_TREE_BLOCK_REF_KEY;
738 	} else {
739 		if (parent > 0)
740 			type = BTRFS_SHARED_DATA_REF_KEY;
741 		else
742 			type = BTRFS_EXTENT_DATA_REF_KEY;
743 	}
744 	return type;
745 }
746 
747 static int find_next_key(struct btrfs_path *path, int level,
748 			 struct btrfs_key *key)
749 
750 {
751 	for (; level < BTRFS_MAX_LEVEL; level++) {
752 		if (!path->nodes[level])
753 			break;
754 		if (path->slots[level] + 1 >=
755 		    btrfs_header_nritems(path->nodes[level]))
756 			continue;
757 		if (level == 0)
758 			btrfs_item_key_to_cpu(path->nodes[level], key,
759 					      path->slots[level] + 1);
760 		else
761 			btrfs_node_key_to_cpu(path->nodes[level], key,
762 					      path->slots[level] + 1);
763 		return 0;
764 	}
765 	return 1;
766 }
767 
768 /*
769  * look for inline back ref. if back ref is found, *ref_ret is set
770  * to the address of inline back ref, and 0 is returned.
771  *
772  * if back ref isn't found, *ref_ret is set to the address where it
773  * should be inserted, and -ENOENT is returned.
774  *
775  * if insert is true and there are too many inline back refs, the path
776  * points to the extent item, and -EAGAIN is returned.
777  *
778  * NOTE: inline back refs are ordered in the same way that back ref
779  *	 items in the tree are ordered.
780  */
781 static noinline_for_stack
782 int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
783 				 struct btrfs_path *path,
784 				 struct btrfs_extent_inline_ref **ref_ret,
785 				 u64 bytenr, u64 num_bytes,
786 				 u64 parent, u64 root_objectid,
787 				 u64 owner, u64 offset, int insert)
788 {
789 	struct btrfs_fs_info *fs_info = trans->fs_info;
790 	struct btrfs_root *root = fs_info->extent_root;
791 	struct btrfs_key key;
792 	struct extent_buffer *leaf;
793 	struct btrfs_extent_item *ei;
794 	struct btrfs_extent_inline_ref *iref;
795 	u64 flags;
796 	u64 item_size;
797 	unsigned long ptr;
798 	unsigned long end;
799 	int extra_size;
800 	int type;
801 	int want;
802 	int ret;
803 	int err = 0;
804 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
805 	int needed;
806 
807 	key.objectid = bytenr;
808 	key.type = BTRFS_EXTENT_ITEM_KEY;
809 	key.offset = num_bytes;
810 
811 	want = extent_ref_type(parent, owner);
812 	if (insert) {
813 		extra_size = btrfs_extent_inline_ref_size(want);
814 		path->search_for_extension = 1;
815 		path->keep_locks = 1;
816 	} else
817 		extra_size = -1;
818 
819 	/*
820 	 * Owner is our level, so we can just add one to get the level for the
821 	 * block we are interested in.
822 	 */
823 	if (skinny_metadata && owner < BTRFS_FIRST_FREE_OBJECTID) {
824 		key.type = BTRFS_METADATA_ITEM_KEY;
825 		key.offset = owner;
826 	}
827 
828 again:
829 	ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
830 	if (ret < 0) {
831 		err = ret;
832 		goto out;
833 	}
834 
835 	/*
836 	 * We may be a newly converted file system which still has the old fat
837 	 * extent entries for metadata, so try and see if we have one of those.
838 	 */
839 	if (ret > 0 && skinny_metadata) {
840 		skinny_metadata = false;
841 		if (path->slots[0]) {
842 			path->slots[0]--;
843 			btrfs_item_key_to_cpu(path->nodes[0], &key,
844 					      path->slots[0]);
845 			if (key.objectid == bytenr &&
846 			    key.type == BTRFS_EXTENT_ITEM_KEY &&
847 			    key.offset == num_bytes)
848 				ret = 0;
849 		}
850 		if (ret) {
851 			key.objectid = bytenr;
852 			key.type = BTRFS_EXTENT_ITEM_KEY;
853 			key.offset = num_bytes;
854 			btrfs_release_path(path);
855 			goto again;
856 		}
857 	}
858 
859 	if (ret && !insert) {
860 		err = -ENOENT;
861 		goto out;
862 	} else if (WARN_ON(ret)) {
863 		err = -EIO;
864 		goto out;
865 	}
866 
867 	leaf = path->nodes[0];
868 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
869 	if (unlikely(item_size < sizeof(*ei))) {
870 		err = -EINVAL;
871 		btrfs_print_v0_err(fs_info);
872 		btrfs_abort_transaction(trans, err);
873 		goto out;
874 	}
875 
876 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
877 	flags = btrfs_extent_flags(leaf, ei);
878 
879 	ptr = (unsigned long)(ei + 1);
880 	end = (unsigned long)ei + item_size;
881 
882 	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK && !skinny_metadata) {
883 		ptr += sizeof(struct btrfs_tree_block_info);
884 		BUG_ON(ptr > end);
885 	}
886 
887 	if (owner >= BTRFS_FIRST_FREE_OBJECTID)
888 		needed = BTRFS_REF_TYPE_DATA;
889 	else
890 		needed = BTRFS_REF_TYPE_BLOCK;
891 
892 	err = -ENOENT;
893 	while (1) {
894 		if (ptr >= end) {
895 			WARN_ON(ptr > end);
896 			break;
897 		}
898 		iref = (struct btrfs_extent_inline_ref *)ptr;
899 		type = btrfs_get_extent_inline_ref_type(leaf, iref, needed);
900 		if (type == BTRFS_REF_TYPE_INVALID) {
901 			err = -EUCLEAN;
902 			goto out;
903 		}
904 
905 		if (want < type)
906 			break;
907 		if (want > type) {
908 			ptr += btrfs_extent_inline_ref_size(type);
909 			continue;
910 		}
911 
912 		if (type == BTRFS_EXTENT_DATA_REF_KEY) {
913 			struct btrfs_extent_data_ref *dref;
914 			dref = (struct btrfs_extent_data_ref *)(&iref->offset);
915 			if (match_extent_data_ref(leaf, dref, root_objectid,
916 						  owner, offset)) {
917 				err = 0;
918 				break;
919 			}
920 			if (hash_extent_data_ref_item(leaf, dref) <
921 			    hash_extent_data_ref(root_objectid, owner, offset))
922 				break;
923 		} else {
924 			u64 ref_offset;
925 			ref_offset = btrfs_extent_inline_ref_offset(leaf, iref);
926 			if (parent > 0) {
927 				if (parent == ref_offset) {
928 					err = 0;
929 					break;
930 				}
931 				if (ref_offset < parent)
932 					break;
933 			} else {
934 				if (root_objectid == ref_offset) {
935 					err = 0;
936 					break;
937 				}
938 				if (ref_offset < root_objectid)
939 					break;
940 			}
941 		}
942 		ptr += btrfs_extent_inline_ref_size(type);
943 	}
944 	if (err == -ENOENT && insert) {
945 		if (item_size + extra_size >=
946 		    BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
947 			err = -EAGAIN;
948 			goto out;
949 		}
950 		/*
951 		 * To add new inline back ref, we have to make sure
952 		 * there is no corresponding back ref item.
953 		 * For simplicity, we just do not add new inline back
954 		 * ref if there is any kind of item for this block
955 		 */
956 		if (find_next_key(path, 0, &key) == 0 &&
957 		    key.objectid == bytenr &&
958 		    key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
959 			err = -EAGAIN;
960 			goto out;
961 		}
962 	}
963 	*ref_ret = (struct btrfs_extent_inline_ref *)ptr;
964 out:
965 	if (insert) {
966 		path->keep_locks = 0;
967 		path->search_for_extension = 0;
968 		btrfs_unlock_up_safe(path, 1);
969 	}
970 	return err;
971 }
972 
973 /*
974  * helper to add new inline back ref
975  */
976 static noinline_for_stack
977 void setup_inline_extent_backref(struct btrfs_fs_info *fs_info,
978 				 struct btrfs_path *path,
979 				 struct btrfs_extent_inline_ref *iref,
980 				 u64 parent, u64 root_objectid,
981 				 u64 owner, u64 offset, int refs_to_add,
982 				 struct btrfs_delayed_extent_op *extent_op)
983 {
984 	struct extent_buffer *leaf;
985 	struct btrfs_extent_item *ei;
986 	unsigned long ptr;
987 	unsigned long end;
988 	unsigned long item_offset;
989 	u64 refs;
990 	int size;
991 	int type;
992 
993 	leaf = path->nodes[0];
994 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
995 	item_offset = (unsigned long)iref - (unsigned long)ei;
996 
997 	type = extent_ref_type(parent, owner);
998 	size = btrfs_extent_inline_ref_size(type);
999 
1000 	btrfs_extend_item(path, size);
1001 
1002 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1003 	refs = btrfs_extent_refs(leaf, ei);
1004 	refs += refs_to_add;
1005 	btrfs_set_extent_refs(leaf, ei, refs);
1006 	if (extent_op)
1007 		__run_delayed_extent_op(extent_op, leaf, ei);
1008 
1009 	ptr = (unsigned long)ei + item_offset;
1010 	end = (unsigned long)ei + btrfs_item_size_nr(leaf, path->slots[0]);
1011 	if (ptr < end - size)
1012 		memmove_extent_buffer(leaf, ptr + size, ptr,
1013 				      end - size - ptr);
1014 
1015 	iref = (struct btrfs_extent_inline_ref *)ptr;
1016 	btrfs_set_extent_inline_ref_type(leaf, iref, type);
1017 	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1018 		struct btrfs_extent_data_ref *dref;
1019 		dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1020 		btrfs_set_extent_data_ref_root(leaf, dref, root_objectid);
1021 		btrfs_set_extent_data_ref_objectid(leaf, dref, owner);
1022 		btrfs_set_extent_data_ref_offset(leaf, dref, offset);
1023 		btrfs_set_extent_data_ref_count(leaf, dref, refs_to_add);
1024 	} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1025 		struct btrfs_shared_data_ref *sref;
1026 		sref = (struct btrfs_shared_data_ref *)(iref + 1);
1027 		btrfs_set_shared_data_ref_count(leaf, sref, refs_to_add);
1028 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
1029 	} else if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
1030 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
1031 	} else {
1032 		btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
1033 	}
1034 	btrfs_mark_buffer_dirty(leaf);
1035 }
1036 
1037 static int lookup_extent_backref(struct btrfs_trans_handle *trans,
1038 				 struct btrfs_path *path,
1039 				 struct btrfs_extent_inline_ref **ref_ret,
1040 				 u64 bytenr, u64 num_bytes, u64 parent,
1041 				 u64 root_objectid, u64 owner, u64 offset)
1042 {
1043 	int ret;
1044 
1045 	ret = lookup_inline_extent_backref(trans, path, ref_ret, bytenr,
1046 					   num_bytes, parent, root_objectid,
1047 					   owner, offset, 0);
1048 	if (ret != -ENOENT)
1049 		return ret;
1050 
1051 	btrfs_release_path(path);
1052 	*ref_ret = NULL;
1053 
1054 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1055 		ret = lookup_tree_block_ref(trans, path, bytenr, parent,
1056 					    root_objectid);
1057 	} else {
1058 		ret = lookup_extent_data_ref(trans, path, bytenr, parent,
1059 					     root_objectid, owner, offset);
1060 	}
1061 	return ret;
1062 }
1063 
1064 /*
1065  * helper to update/remove inline back ref
1066  */
1067 static noinline_for_stack
1068 void update_inline_extent_backref(struct btrfs_path *path,
1069 				  struct btrfs_extent_inline_ref *iref,
1070 				  int refs_to_mod,
1071 				  struct btrfs_delayed_extent_op *extent_op,
1072 				  int *last_ref)
1073 {
1074 	struct extent_buffer *leaf = path->nodes[0];
1075 	struct btrfs_extent_item *ei;
1076 	struct btrfs_extent_data_ref *dref = NULL;
1077 	struct btrfs_shared_data_ref *sref = NULL;
1078 	unsigned long ptr;
1079 	unsigned long end;
1080 	u32 item_size;
1081 	int size;
1082 	int type;
1083 	u64 refs;
1084 
1085 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1086 	refs = btrfs_extent_refs(leaf, ei);
1087 	WARN_ON(refs_to_mod < 0 && refs + refs_to_mod <= 0);
1088 	refs += refs_to_mod;
1089 	btrfs_set_extent_refs(leaf, ei, refs);
1090 	if (extent_op)
1091 		__run_delayed_extent_op(extent_op, leaf, ei);
1092 
1093 	/*
1094 	 * If type is invalid, we should have bailed out after
1095 	 * lookup_inline_extent_backref().
1096 	 */
1097 	type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_ANY);
1098 	ASSERT(type != BTRFS_REF_TYPE_INVALID);
1099 
1100 	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1101 		dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1102 		refs = btrfs_extent_data_ref_count(leaf, dref);
1103 	} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1104 		sref = (struct btrfs_shared_data_ref *)(iref + 1);
1105 		refs = btrfs_shared_data_ref_count(leaf, sref);
1106 	} else {
1107 		refs = 1;
1108 		BUG_ON(refs_to_mod != -1);
1109 	}
1110 
1111 	BUG_ON(refs_to_mod < 0 && refs < -refs_to_mod);
1112 	refs += refs_to_mod;
1113 
1114 	if (refs > 0) {
1115 		if (type == BTRFS_EXTENT_DATA_REF_KEY)
1116 			btrfs_set_extent_data_ref_count(leaf, dref, refs);
1117 		else
1118 			btrfs_set_shared_data_ref_count(leaf, sref, refs);
1119 	} else {
1120 		*last_ref = 1;
1121 		size =  btrfs_extent_inline_ref_size(type);
1122 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1123 		ptr = (unsigned long)iref;
1124 		end = (unsigned long)ei + item_size;
1125 		if (ptr + size < end)
1126 			memmove_extent_buffer(leaf, ptr, ptr + size,
1127 					      end - ptr - size);
1128 		item_size -= size;
1129 		btrfs_truncate_item(path, item_size, 1);
1130 	}
1131 	btrfs_mark_buffer_dirty(leaf);
1132 }
1133 
1134 static noinline_for_stack
1135 int insert_inline_extent_backref(struct btrfs_trans_handle *trans,
1136 				 struct btrfs_path *path,
1137 				 u64 bytenr, u64 num_bytes, u64 parent,
1138 				 u64 root_objectid, u64 owner,
1139 				 u64 offset, int refs_to_add,
1140 				 struct btrfs_delayed_extent_op *extent_op)
1141 {
1142 	struct btrfs_extent_inline_ref *iref;
1143 	int ret;
1144 
1145 	ret = lookup_inline_extent_backref(trans, path, &iref, bytenr,
1146 					   num_bytes, parent, root_objectid,
1147 					   owner, offset, 1);
1148 	if (ret == 0) {
1149 		/*
1150 		 * We're adding refs to a tree block we already own, this
1151 		 * should not happen at all.
1152 		 */
1153 		if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1154 			btrfs_crit(trans->fs_info,
1155 "adding refs to an existing tree ref, bytenr %llu num_bytes %llu root_objectid %llu",
1156 				   bytenr, num_bytes, root_objectid);
1157 			if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) {
1158 				WARN_ON(1);
1159 				btrfs_crit(trans->fs_info,
1160 			"path->slots[0]=%d path->nodes[0]:", path->slots[0]);
1161 				btrfs_print_leaf(path->nodes[0]);
1162 			}
1163 			return -EUCLEAN;
1164 		}
1165 		update_inline_extent_backref(path, iref, refs_to_add,
1166 					     extent_op, NULL);
1167 	} else if (ret == -ENOENT) {
1168 		setup_inline_extent_backref(trans->fs_info, path, iref, parent,
1169 					    root_objectid, owner, offset,
1170 					    refs_to_add, extent_op);
1171 		ret = 0;
1172 	}
1173 	return ret;
1174 }
1175 
1176 static int remove_extent_backref(struct btrfs_trans_handle *trans,
1177 				 struct btrfs_path *path,
1178 				 struct btrfs_extent_inline_ref *iref,
1179 				 int refs_to_drop, int is_data, int *last_ref)
1180 {
1181 	int ret = 0;
1182 
1183 	BUG_ON(!is_data && refs_to_drop != 1);
1184 	if (iref) {
1185 		update_inline_extent_backref(path, iref, -refs_to_drop, NULL,
1186 					     last_ref);
1187 	} else if (is_data) {
1188 		ret = remove_extent_data_ref(trans, path, refs_to_drop,
1189 					     last_ref);
1190 	} else {
1191 		*last_ref = 1;
1192 		ret = btrfs_del_item(trans, trans->fs_info->extent_root, path);
1193 	}
1194 	return ret;
1195 }
1196 
1197 static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
1198 			       u64 *discarded_bytes)
1199 {
1200 	int j, ret = 0;
1201 	u64 bytes_left, end;
1202 	u64 aligned_start = ALIGN(start, 1 << 9);
1203 
1204 	if (WARN_ON(start != aligned_start)) {
1205 		len -= aligned_start - start;
1206 		len = round_down(len, 1 << 9);
1207 		start = aligned_start;
1208 	}
1209 
1210 	*discarded_bytes = 0;
1211 
1212 	if (!len)
1213 		return 0;
1214 
1215 	end = start + len;
1216 	bytes_left = len;
1217 
1218 	/* Skip any superblocks on this device. */
1219 	for (j = 0; j < BTRFS_SUPER_MIRROR_MAX; j++) {
1220 		u64 sb_start = btrfs_sb_offset(j);
1221 		u64 sb_end = sb_start + BTRFS_SUPER_INFO_SIZE;
1222 		u64 size = sb_start - start;
1223 
1224 		if (!in_range(sb_start, start, bytes_left) &&
1225 		    !in_range(sb_end, start, bytes_left) &&
1226 		    !in_range(start, sb_start, BTRFS_SUPER_INFO_SIZE))
1227 			continue;
1228 
1229 		/*
1230 		 * Superblock spans beginning of range.  Adjust start and
1231 		 * try again.
1232 		 */
1233 		if (sb_start <= start) {
1234 			start += sb_end - start;
1235 			if (start > end) {
1236 				bytes_left = 0;
1237 				break;
1238 			}
1239 			bytes_left = end - start;
1240 			continue;
1241 		}
1242 
1243 		if (size) {
1244 			ret = blkdev_issue_discard(bdev, start >> 9, size >> 9,
1245 						   GFP_NOFS, 0);
1246 			if (!ret)
1247 				*discarded_bytes += size;
1248 			else if (ret != -EOPNOTSUPP)
1249 				return ret;
1250 		}
1251 
1252 		start = sb_end;
1253 		if (start > end) {
1254 			bytes_left = 0;
1255 			break;
1256 		}
1257 		bytes_left = end - start;
1258 	}
1259 
1260 	if (bytes_left) {
1261 		ret = blkdev_issue_discard(bdev, start >> 9, bytes_left >> 9,
1262 					   GFP_NOFS, 0);
1263 		if (!ret)
1264 			*discarded_bytes += bytes_left;
1265 	}
1266 	return ret;
1267 }
1268 
1269 static int do_discard_extent(struct btrfs_bio_stripe *stripe, u64 *bytes)
1270 {
1271 	struct btrfs_device *dev = stripe->dev;
1272 	struct btrfs_fs_info *fs_info = dev->fs_info;
1273 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1274 	u64 phys = stripe->physical;
1275 	u64 len = stripe->length;
1276 	u64 discarded = 0;
1277 	int ret = 0;
1278 
1279 	/* Zone reset on a zoned filesystem */
1280 	if (btrfs_can_zone_reset(dev, phys, len)) {
1281 		u64 src_disc;
1282 
1283 		ret = btrfs_reset_device_zone(dev, phys, len, &discarded);
1284 		if (ret)
1285 			goto out;
1286 
1287 		if (!btrfs_dev_replace_is_ongoing(dev_replace) ||
1288 		    dev != dev_replace->srcdev)
1289 			goto out;
1290 
1291 		src_disc = discarded;
1292 
1293 		/* Send to replace target as well */
1294 		ret = btrfs_reset_device_zone(dev_replace->tgtdev, phys, len,
1295 					      &discarded);
1296 		discarded += src_disc;
1297 	} else if (blk_queue_discard(bdev_get_queue(stripe->dev->bdev))) {
1298 		ret = btrfs_issue_discard(dev->bdev, phys, len, &discarded);
1299 	} else {
1300 		ret = 0;
1301 		*bytes = 0;
1302 	}
1303 
1304 out:
1305 	*bytes = discarded;
1306 	return ret;
1307 }
1308 
1309 int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
1310 			 u64 num_bytes, u64 *actual_bytes)
1311 {
1312 	int ret = 0;
1313 	u64 discarded_bytes = 0;
1314 	u64 end = bytenr + num_bytes;
1315 	u64 cur = bytenr;
1316 	struct btrfs_bio *bbio = NULL;
1317 
1318 
1319 	/*
1320 	 * Avoid races with device replace and make sure our bbio has devices
1321 	 * associated to its stripes that don't go away while we are discarding.
1322 	 */
1323 	btrfs_bio_counter_inc_blocked(fs_info);
1324 	while (cur < end) {
1325 		struct btrfs_bio_stripe *stripe;
1326 		int i;
1327 
1328 		num_bytes = end - cur;
1329 		/* Tell the block device(s) that the sectors can be discarded */
1330 		ret = btrfs_map_block(fs_info, BTRFS_MAP_DISCARD, cur,
1331 				      &num_bytes, &bbio, 0);
1332 		/*
1333 		 * Error can be -ENOMEM, -ENOENT (no such chunk mapping) or
1334 		 * -EOPNOTSUPP. For any such error, @num_bytes is not updated,
1335 		 * thus we can't continue anyway.
1336 		 */
1337 		if (ret < 0)
1338 			goto out;
1339 
1340 		stripe = bbio->stripes;
1341 		for (i = 0; i < bbio->num_stripes; i++, stripe++) {
1342 			u64 bytes;
1343 			struct btrfs_device *device = stripe->dev;
1344 
1345 			if (!device->bdev) {
1346 				ASSERT(btrfs_test_opt(fs_info, DEGRADED));
1347 				continue;
1348 			}
1349 
1350 			if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
1351 				continue;
1352 
1353 			ret = do_discard_extent(stripe, &bytes);
1354 			if (!ret) {
1355 				discarded_bytes += bytes;
1356 			} else if (ret != -EOPNOTSUPP) {
1357 				/*
1358 				 * Logic errors or -ENOMEM, or -EIO, but
1359 				 * unlikely to happen.
1360 				 *
1361 				 * And since there are two loops, explicitly
1362 				 * go to out to avoid confusion.
1363 				 */
1364 				btrfs_put_bbio(bbio);
1365 				goto out;
1366 			}
1367 
1368 			/*
1369 			 * Just in case we get back EOPNOTSUPP for some reason,
1370 			 * just ignore the return value so we don't screw up
1371 			 * people calling discard_extent.
1372 			 */
1373 			ret = 0;
1374 		}
1375 		btrfs_put_bbio(bbio);
1376 		cur += num_bytes;
1377 	}
1378 out:
1379 	btrfs_bio_counter_dec(fs_info);
1380 
1381 	if (actual_bytes)
1382 		*actual_bytes = discarded_bytes;
1383 
1384 
1385 	if (ret == -EOPNOTSUPP)
1386 		ret = 0;
1387 	return ret;
1388 }
1389 
1390 /* Can return -ENOMEM */
1391 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
1392 			 struct btrfs_ref *generic_ref)
1393 {
1394 	struct btrfs_fs_info *fs_info = trans->fs_info;
1395 	int ret;
1396 
1397 	ASSERT(generic_ref->type != BTRFS_REF_NOT_SET &&
1398 	       generic_ref->action);
1399 	BUG_ON(generic_ref->type == BTRFS_REF_METADATA &&
1400 	       generic_ref->tree_ref.root == BTRFS_TREE_LOG_OBJECTID);
1401 
1402 	if (generic_ref->type == BTRFS_REF_METADATA)
1403 		ret = btrfs_add_delayed_tree_ref(trans, generic_ref, NULL);
1404 	else
1405 		ret = btrfs_add_delayed_data_ref(trans, generic_ref, 0);
1406 
1407 	btrfs_ref_tree_mod(fs_info, generic_ref);
1408 
1409 	return ret;
1410 }
1411 
1412 /*
1413  * __btrfs_inc_extent_ref - insert backreference for a given extent
1414  *
1415  * The counterpart is in __btrfs_free_extent(), with examples and more details
1416  * how it works.
1417  *
1418  * @trans:	    Handle of transaction
1419  *
1420  * @node:	    The delayed ref node used to get the bytenr/length for
1421  *		    extent whose references are incremented.
1422  *
1423  * @parent:	    If this is a shared extent (BTRFS_SHARED_DATA_REF_KEY/
1424  *		    BTRFS_SHARED_BLOCK_REF_KEY) then it holds the logical
1425  *		    bytenr of the parent block. Since new extents are always
1426  *		    created with indirect references, this will only be the case
1427  *		    when relocating a shared extent. In that case, root_objectid
1428  *		    will be BTRFS_TREE_RELOC_OBJECTID. Otherwise, parent must
1429  *		    be 0
1430  *
1431  * @root_objectid:  The id of the root where this modification has originated,
1432  *		    this can be either one of the well-known metadata trees or
1433  *		    the subvolume id which references this extent.
1434  *
1435  * @owner:	    For data extents it is the inode number of the owning file.
1436  *		    For metadata extents this parameter holds the level in the
1437  *		    tree of the extent.
1438  *
1439  * @offset:	    For metadata extents the offset is ignored and is currently
1440  *		    always passed as 0. For data extents it is the fileoffset
1441  *		    this extent belongs to.
1442  *
1443  * @refs_to_add     Number of references to add
1444  *
1445  * @extent_op       Pointer to a structure, holding information necessary when
1446  *                  updating a tree block's flags
1447  *
1448  */
1449 static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
1450 				  struct btrfs_delayed_ref_node *node,
1451 				  u64 parent, u64 root_objectid,
1452 				  u64 owner, u64 offset, int refs_to_add,
1453 				  struct btrfs_delayed_extent_op *extent_op)
1454 {
1455 	struct btrfs_path *path;
1456 	struct extent_buffer *leaf;
1457 	struct btrfs_extent_item *item;
1458 	struct btrfs_key key;
1459 	u64 bytenr = node->bytenr;
1460 	u64 num_bytes = node->num_bytes;
1461 	u64 refs;
1462 	int ret;
1463 
1464 	path = btrfs_alloc_path();
1465 	if (!path)
1466 		return -ENOMEM;
1467 
1468 	/* this will setup the path even if it fails to insert the back ref */
1469 	ret = insert_inline_extent_backref(trans, path, bytenr, num_bytes,
1470 					   parent, root_objectid, owner,
1471 					   offset, refs_to_add, extent_op);
1472 	if ((ret < 0 && ret != -EAGAIN) || !ret)
1473 		goto out;
1474 
1475 	/*
1476 	 * Ok we had -EAGAIN which means we didn't have space to insert and
1477 	 * inline extent ref, so just update the reference count and add a
1478 	 * normal backref.
1479 	 */
1480 	leaf = path->nodes[0];
1481 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1482 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1483 	refs = btrfs_extent_refs(leaf, item);
1484 	btrfs_set_extent_refs(leaf, item, refs + refs_to_add);
1485 	if (extent_op)
1486 		__run_delayed_extent_op(extent_op, leaf, item);
1487 
1488 	btrfs_mark_buffer_dirty(leaf);
1489 	btrfs_release_path(path);
1490 
1491 	/* now insert the actual backref */
1492 	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1493 		BUG_ON(refs_to_add != 1);
1494 		ret = insert_tree_block_ref(trans, path, bytenr, parent,
1495 					    root_objectid);
1496 	} else {
1497 		ret = insert_extent_data_ref(trans, path, bytenr, parent,
1498 					     root_objectid, owner, offset,
1499 					     refs_to_add);
1500 	}
1501 	if (ret)
1502 		btrfs_abort_transaction(trans, ret);
1503 out:
1504 	btrfs_free_path(path);
1505 	return ret;
1506 }
1507 
1508 static int run_delayed_data_ref(struct btrfs_trans_handle *trans,
1509 				struct btrfs_delayed_ref_node *node,
1510 				struct btrfs_delayed_extent_op *extent_op,
1511 				int insert_reserved)
1512 {
1513 	int ret = 0;
1514 	struct btrfs_delayed_data_ref *ref;
1515 	struct btrfs_key ins;
1516 	u64 parent = 0;
1517 	u64 ref_root = 0;
1518 	u64 flags = 0;
1519 
1520 	ins.objectid = node->bytenr;
1521 	ins.offset = node->num_bytes;
1522 	ins.type = BTRFS_EXTENT_ITEM_KEY;
1523 
1524 	ref = btrfs_delayed_node_to_data_ref(node);
1525 	trace_run_delayed_data_ref(trans->fs_info, node, ref, node->action);
1526 
1527 	if (node->type == BTRFS_SHARED_DATA_REF_KEY)
1528 		parent = ref->parent;
1529 	ref_root = ref->root;
1530 
1531 	if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
1532 		if (extent_op)
1533 			flags |= extent_op->flags_to_set;
1534 		ret = alloc_reserved_file_extent(trans, parent, ref_root,
1535 						 flags, ref->objectid,
1536 						 ref->offset, &ins,
1537 						 node->ref_mod);
1538 	} else if (node->action == BTRFS_ADD_DELAYED_REF) {
1539 		ret = __btrfs_inc_extent_ref(trans, node, parent, ref_root,
1540 					     ref->objectid, ref->offset,
1541 					     node->ref_mod, extent_op);
1542 	} else if (node->action == BTRFS_DROP_DELAYED_REF) {
1543 		ret = __btrfs_free_extent(trans, node, parent,
1544 					  ref_root, ref->objectid,
1545 					  ref->offset, node->ref_mod,
1546 					  extent_op);
1547 	} else {
1548 		BUG();
1549 	}
1550 	return ret;
1551 }
1552 
1553 static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
1554 				    struct extent_buffer *leaf,
1555 				    struct btrfs_extent_item *ei)
1556 {
1557 	u64 flags = btrfs_extent_flags(leaf, ei);
1558 	if (extent_op->update_flags) {
1559 		flags |= extent_op->flags_to_set;
1560 		btrfs_set_extent_flags(leaf, ei, flags);
1561 	}
1562 
1563 	if (extent_op->update_key) {
1564 		struct btrfs_tree_block_info *bi;
1565 		BUG_ON(!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK));
1566 		bi = (struct btrfs_tree_block_info *)(ei + 1);
1567 		btrfs_set_tree_block_key(leaf, bi, &extent_op->key);
1568 	}
1569 }
1570 
1571 static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
1572 				 struct btrfs_delayed_ref_head *head,
1573 				 struct btrfs_delayed_extent_op *extent_op)
1574 {
1575 	struct btrfs_fs_info *fs_info = trans->fs_info;
1576 	struct btrfs_key key;
1577 	struct btrfs_path *path;
1578 	struct btrfs_extent_item *ei;
1579 	struct extent_buffer *leaf;
1580 	u32 item_size;
1581 	int ret;
1582 	int err = 0;
1583 	int metadata = !extent_op->is_data;
1584 
1585 	if (TRANS_ABORTED(trans))
1586 		return 0;
1587 
1588 	if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1589 		metadata = 0;
1590 
1591 	path = btrfs_alloc_path();
1592 	if (!path)
1593 		return -ENOMEM;
1594 
1595 	key.objectid = head->bytenr;
1596 
1597 	if (metadata) {
1598 		key.type = BTRFS_METADATA_ITEM_KEY;
1599 		key.offset = extent_op->level;
1600 	} else {
1601 		key.type = BTRFS_EXTENT_ITEM_KEY;
1602 		key.offset = head->num_bytes;
1603 	}
1604 
1605 again:
1606 	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 1);
1607 	if (ret < 0) {
1608 		err = ret;
1609 		goto out;
1610 	}
1611 	if (ret > 0) {
1612 		if (metadata) {
1613 			if (path->slots[0] > 0) {
1614 				path->slots[0]--;
1615 				btrfs_item_key_to_cpu(path->nodes[0], &key,
1616 						      path->slots[0]);
1617 				if (key.objectid == head->bytenr &&
1618 				    key.type == BTRFS_EXTENT_ITEM_KEY &&
1619 				    key.offset == head->num_bytes)
1620 					ret = 0;
1621 			}
1622 			if (ret > 0) {
1623 				btrfs_release_path(path);
1624 				metadata = 0;
1625 
1626 				key.objectid = head->bytenr;
1627 				key.offset = head->num_bytes;
1628 				key.type = BTRFS_EXTENT_ITEM_KEY;
1629 				goto again;
1630 			}
1631 		} else {
1632 			err = -EIO;
1633 			goto out;
1634 		}
1635 	}
1636 
1637 	leaf = path->nodes[0];
1638 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1639 
1640 	if (unlikely(item_size < sizeof(*ei))) {
1641 		err = -EINVAL;
1642 		btrfs_print_v0_err(fs_info);
1643 		btrfs_abort_transaction(trans, err);
1644 		goto out;
1645 	}
1646 
1647 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1648 	__run_delayed_extent_op(extent_op, leaf, ei);
1649 
1650 	btrfs_mark_buffer_dirty(leaf);
1651 out:
1652 	btrfs_free_path(path);
1653 	return err;
1654 }
1655 
1656 static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
1657 				struct btrfs_delayed_ref_node *node,
1658 				struct btrfs_delayed_extent_op *extent_op,
1659 				int insert_reserved)
1660 {
1661 	int ret = 0;
1662 	struct btrfs_delayed_tree_ref *ref;
1663 	u64 parent = 0;
1664 	u64 ref_root = 0;
1665 
1666 	ref = btrfs_delayed_node_to_tree_ref(node);
1667 	trace_run_delayed_tree_ref(trans->fs_info, node, ref, node->action);
1668 
1669 	if (node->type == BTRFS_SHARED_BLOCK_REF_KEY)
1670 		parent = ref->parent;
1671 	ref_root = ref->root;
1672 
1673 	if (node->ref_mod != 1) {
1674 		btrfs_err(trans->fs_info,
1675 	"btree block(%llu) has %d references rather than 1: action %d ref_root %llu parent %llu",
1676 			  node->bytenr, node->ref_mod, node->action, ref_root,
1677 			  parent);
1678 		return -EIO;
1679 	}
1680 	if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
1681 		BUG_ON(!extent_op || !extent_op->update_flags);
1682 		ret = alloc_reserved_tree_block(trans, node, extent_op);
1683 	} else if (node->action == BTRFS_ADD_DELAYED_REF) {
1684 		ret = __btrfs_inc_extent_ref(trans, node, parent, ref_root,
1685 					     ref->level, 0, 1, extent_op);
1686 	} else if (node->action == BTRFS_DROP_DELAYED_REF) {
1687 		ret = __btrfs_free_extent(trans, node, parent, ref_root,
1688 					  ref->level, 0, 1, extent_op);
1689 	} else {
1690 		BUG();
1691 	}
1692 	return ret;
1693 }
1694 
1695 /* helper function to actually process a single delayed ref entry */
1696 static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
1697 			       struct btrfs_delayed_ref_node *node,
1698 			       struct btrfs_delayed_extent_op *extent_op,
1699 			       int insert_reserved)
1700 {
1701 	int ret = 0;
1702 
1703 	if (TRANS_ABORTED(trans)) {
1704 		if (insert_reserved)
1705 			btrfs_pin_extent(trans, node->bytenr, node->num_bytes, 1);
1706 		return 0;
1707 	}
1708 
1709 	if (node->type == BTRFS_TREE_BLOCK_REF_KEY ||
1710 	    node->type == BTRFS_SHARED_BLOCK_REF_KEY)
1711 		ret = run_delayed_tree_ref(trans, node, extent_op,
1712 					   insert_reserved);
1713 	else if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
1714 		 node->type == BTRFS_SHARED_DATA_REF_KEY)
1715 		ret = run_delayed_data_ref(trans, node, extent_op,
1716 					   insert_reserved);
1717 	else
1718 		BUG();
1719 	if (ret && insert_reserved)
1720 		btrfs_pin_extent(trans, node->bytenr, node->num_bytes, 1);
1721 	return ret;
1722 }
1723 
1724 static inline struct btrfs_delayed_ref_node *
1725 select_delayed_ref(struct btrfs_delayed_ref_head *head)
1726 {
1727 	struct btrfs_delayed_ref_node *ref;
1728 
1729 	if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
1730 		return NULL;
1731 
1732 	/*
1733 	 * Select a delayed ref of type BTRFS_ADD_DELAYED_REF first.
1734 	 * This is to prevent a ref count from going down to zero, which deletes
1735 	 * the extent item from the extent tree, when there still are references
1736 	 * to add, which would fail because they would not find the extent item.
1737 	 */
1738 	if (!list_empty(&head->ref_add_list))
1739 		return list_first_entry(&head->ref_add_list,
1740 				struct btrfs_delayed_ref_node, add_list);
1741 
1742 	ref = rb_entry(rb_first_cached(&head->ref_tree),
1743 		       struct btrfs_delayed_ref_node, ref_node);
1744 	ASSERT(list_empty(&ref->add_list));
1745 	return ref;
1746 }
1747 
1748 static void unselect_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
1749 				      struct btrfs_delayed_ref_head *head)
1750 {
1751 	spin_lock(&delayed_refs->lock);
1752 	head->processing = 0;
1753 	delayed_refs->num_heads_ready++;
1754 	spin_unlock(&delayed_refs->lock);
1755 	btrfs_delayed_ref_unlock(head);
1756 }
1757 
1758 static struct btrfs_delayed_extent_op *cleanup_extent_op(
1759 				struct btrfs_delayed_ref_head *head)
1760 {
1761 	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
1762 
1763 	if (!extent_op)
1764 		return NULL;
1765 
1766 	if (head->must_insert_reserved) {
1767 		head->extent_op = NULL;
1768 		btrfs_free_delayed_extent_op(extent_op);
1769 		return NULL;
1770 	}
1771 	return extent_op;
1772 }
1773 
1774 static int run_and_cleanup_extent_op(struct btrfs_trans_handle *trans,
1775 				     struct btrfs_delayed_ref_head *head)
1776 {
1777 	struct btrfs_delayed_extent_op *extent_op;
1778 	int ret;
1779 
1780 	extent_op = cleanup_extent_op(head);
1781 	if (!extent_op)
1782 		return 0;
1783 	head->extent_op = NULL;
1784 	spin_unlock(&head->lock);
1785 	ret = run_delayed_extent_op(trans, head, extent_op);
1786 	btrfs_free_delayed_extent_op(extent_op);
1787 	return ret ? ret : 1;
1788 }
1789 
1790 void btrfs_cleanup_ref_head_accounting(struct btrfs_fs_info *fs_info,
1791 				  struct btrfs_delayed_ref_root *delayed_refs,
1792 				  struct btrfs_delayed_ref_head *head)
1793 {
1794 	int nr_items = 1;	/* Dropping this ref head update. */
1795 
1796 	/*
1797 	 * We had csum deletions accounted for in our delayed refs rsv, we need
1798 	 * to drop the csum leaves for this update from our delayed_refs_rsv.
1799 	 */
1800 	if (head->total_ref_mod < 0 && head->is_data) {
1801 		spin_lock(&delayed_refs->lock);
1802 		delayed_refs->pending_csums -= head->num_bytes;
1803 		spin_unlock(&delayed_refs->lock);
1804 		nr_items += btrfs_csum_bytes_to_leaves(fs_info, head->num_bytes);
1805 	}
1806 
1807 	btrfs_delayed_refs_rsv_release(fs_info, nr_items);
1808 }
1809 
1810 static int cleanup_ref_head(struct btrfs_trans_handle *trans,
1811 			    struct btrfs_delayed_ref_head *head)
1812 {
1813 
1814 	struct btrfs_fs_info *fs_info = trans->fs_info;
1815 	struct btrfs_delayed_ref_root *delayed_refs;
1816 	int ret;
1817 
1818 	delayed_refs = &trans->transaction->delayed_refs;
1819 
1820 	ret = run_and_cleanup_extent_op(trans, head);
1821 	if (ret < 0) {
1822 		unselect_delayed_ref_head(delayed_refs, head);
1823 		btrfs_debug(fs_info, "run_delayed_extent_op returned %d", ret);
1824 		return ret;
1825 	} else if (ret) {
1826 		return ret;
1827 	}
1828 
1829 	/*
1830 	 * Need to drop our head ref lock and re-acquire the delayed ref lock
1831 	 * and then re-check to make sure nobody got added.
1832 	 */
1833 	spin_unlock(&head->lock);
1834 	spin_lock(&delayed_refs->lock);
1835 	spin_lock(&head->lock);
1836 	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root) || head->extent_op) {
1837 		spin_unlock(&head->lock);
1838 		spin_unlock(&delayed_refs->lock);
1839 		return 1;
1840 	}
1841 	btrfs_delete_ref_head(delayed_refs, head);
1842 	spin_unlock(&head->lock);
1843 	spin_unlock(&delayed_refs->lock);
1844 
1845 	if (head->must_insert_reserved) {
1846 		btrfs_pin_extent(trans, head->bytenr, head->num_bytes, 1);
1847 		if (head->is_data) {
1848 			ret = btrfs_del_csums(trans, fs_info->csum_root,
1849 					      head->bytenr, head->num_bytes);
1850 		}
1851 	}
1852 
1853 	btrfs_cleanup_ref_head_accounting(fs_info, delayed_refs, head);
1854 
1855 	trace_run_delayed_ref_head(fs_info, head, 0);
1856 	btrfs_delayed_ref_unlock(head);
1857 	btrfs_put_delayed_ref_head(head);
1858 	return ret;
1859 }
1860 
1861 static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(
1862 					struct btrfs_trans_handle *trans)
1863 {
1864 	struct btrfs_delayed_ref_root *delayed_refs =
1865 		&trans->transaction->delayed_refs;
1866 	struct btrfs_delayed_ref_head *head = NULL;
1867 	int ret;
1868 
1869 	spin_lock(&delayed_refs->lock);
1870 	head = btrfs_select_ref_head(delayed_refs);
1871 	if (!head) {
1872 		spin_unlock(&delayed_refs->lock);
1873 		return head;
1874 	}
1875 
1876 	/*
1877 	 * Grab the lock that says we are going to process all the refs for
1878 	 * this head
1879 	 */
1880 	ret = btrfs_delayed_ref_lock(delayed_refs, head);
1881 	spin_unlock(&delayed_refs->lock);
1882 
1883 	/*
1884 	 * We may have dropped the spin lock to get the head mutex lock, and
1885 	 * that might have given someone else time to free the head.  If that's
1886 	 * true, it has been removed from our list and we can move on.
1887 	 */
1888 	if (ret == -EAGAIN)
1889 		head = ERR_PTR(-EAGAIN);
1890 
1891 	return head;
1892 }
1893 
1894 static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,
1895 				    struct btrfs_delayed_ref_head *locked_ref,
1896 				    unsigned long *run_refs)
1897 {
1898 	struct btrfs_fs_info *fs_info = trans->fs_info;
1899 	struct btrfs_delayed_ref_root *delayed_refs;
1900 	struct btrfs_delayed_extent_op *extent_op;
1901 	struct btrfs_delayed_ref_node *ref;
1902 	int must_insert_reserved = 0;
1903 	int ret;
1904 
1905 	delayed_refs = &trans->transaction->delayed_refs;
1906 
1907 	lockdep_assert_held(&locked_ref->mutex);
1908 	lockdep_assert_held(&locked_ref->lock);
1909 
1910 	while ((ref = select_delayed_ref(locked_ref))) {
1911 		if (ref->seq &&
1912 		    btrfs_check_delayed_seq(fs_info, ref->seq)) {
1913 			spin_unlock(&locked_ref->lock);
1914 			unselect_delayed_ref_head(delayed_refs, locked_ref);
1915 			return -EAGAIN;
1916 		}
1917 
1918 		(*run_refs)++;
1919 		ref->in_tree = 0;
1920 		rb_erase_cached(&ref->ref_node, &locked_ref->ref_tree);
1921 		RB_CLEAR_NODE(&ref->ref_node);
1922 		if (!list_empty(&ref->add_list))
1923 			list_del(&ref->add_list);
1924 		/*
1925 		 * When we play the delayed ref, also correct the ref_mod on
1926 		 * head
1927 		 */
1928 		switch (ref->action) {
1929 		case BTRFS_ADD_DELAYED_REF:
1930 		case BTRFS_ADD_DELAYED_EXTENT:
1931 			locked_ref->ref_mod -= ref->ref_mod;
1932 			break;
1933 		case BTRFS_DROP_DELAYED_REF:
1934 			locked_ref->ref_mod += ref->ref_mod;
1935 			break;
1936 		default:
1937 			WARN_ON(1);
1938 		}
1939 		atomic_dec(&delayed_refs->num_entries);
1940 
1941 		/*
1942 		 * Record the must_insert_reserved flag before we drop the
1943 		 * spin lock.
1944 		 */
1945 		must_insert_reserved = locked_ref->must_insert_reserved;
1946 		locked_ref->must_insert_reserved = 0;
1947 
1948 		extent_op = locked_ref->extent_op;
1949 		locked_ref->extent_op = NULL;
1950 		spin_unlock(&locked_ref->lock);
1951 
1952 		ret = run_one_delayed_ref(trans, ref, extent_op,
1953 					  must_insert_reserved);
1954 
1955 		btrfs_free_delayed_extent_op(extent_op);
1956 		if (ret) {
1957 			unselect_delayed_ref_head(delayed_refs, locked_ref);
1958 			btrfs_put_delayed_ref(ref);
1959 			btrfs_debug(fs_info, "run_one_delayed_ref returned %d",
1960 				    ret);
1961 			return ret;
1962 		}
1963 
1964 		btrfs_put_delayed_ref(ref);
1965 		cond_resched();
1966 
1967 		spin_lock(&locked_ref->lock);
1968 		btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
1969 	}
1970 
1971 	return 0;
1972 }
1973 
1974 /*
1975  * Returns 0 on success or if called with an already aborted transaction.
1976  * Returns -ENOMEM or -EIO on failure and will abort the transaction.
1977  */
1978 static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
1979 					     unsigned long nr)
1980 {
1981 	struct btrfs_fs_info *fs_info = trans->fs_info;
1982 	struct btrfs_delayed_ref_root *delayed_refs;
1983 	struct btrfs_delayed_ref_head *locked_ref = NULL;
1984 	ktime_t start = ktime_get();
1985 	int ret;
1986 	unsigned long count = 0;
1987 	unsigned long actual_count = 0;
1988 
1989 	delayed_refs = &trans->transaction->delayed_refs;
1990 	do {
1991 		if (!locked_ref) {
1992 			locked_ref = btrfs_obtain_ref_head(trans);
1993 			if (IS_ERR_OR_NULL(locked_ref)) {
1994 				if (PTR_ERR(locked_ref) == -EAGAIN) {
1995 					continue;
1996 				} else {
1997 					break;
1998 				}
1999 			}
2000 			count++;
2001 		}
2002 		/*
2003 		 * We need to try and merge add/drops of the same ref since we
2004 		 * can run into issues with relocate dropping the implicit ref
2005 		 * and then it being added back again before the drop can
2006 		 * finish.  If we merged anything we need to re-loop so we can
2007 		 * get a good ref.
2008 		 * Or we can get node references of the same type that weren't
2009 		 * merged when created due to bumps in the tree mod seq, and
2010 		 * we need to merge them to prevent adding an inline extent
2011 		 * backref before dropping it (triggering a BUG_ON at
2012 		 * insert_inline_extent_backref()).
2013 		 */
2014 		spin_lock(&locked_ref->lock);
2015 		btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
2016 
2017 		ret = btrfs_run_delayed_refs_for_head(trans, locked_ref,
2018 						      &actual_count);
2019 		if (ret < 0 && ret != -EAGAIN) {
2020 			/*
2021 			 * Error, btrfs_run_delayed_refs_for_head already
2022 			 * unlocked everything so just bail out
2023 			 */
2024 			return ret;
2025 		} else if (!ret) {
2026 			/*
2027 			 * Success, perform the usual cleanup of a processed
2028 			 * head
2029 			 */
2030 			ret = cleanup_ref_head(trans, locked_ref);
2031 			if (ret > 0 ) {
2032 				/* We dropped our lock, we need to loop. */
2033 				ret = 0;
2034 				continue;
2035 			} else if (ret) {
2036 				return ret;
2037 			}
2038 		}
2039 
2040 		/*
2041 		 * Either success case or btrfs_run_delayed_refs_for_head
2042 		 * returned -EAGAIN, meaning we need to select another head
2043 		 */
2044 
2045 		locked_ref = NULL;
2046 		cond_resched();
2047 	} while ((nr != -1 && count < nr) || locked_ref);
2048 
2049 	/*
2050 	 * We don't want to include ref heads since we can have empty ref heads
2051 	 * and those will drastically skew our runtime down since we just do
2052 	 * accounting, no actual extent tree updates.
2053 	 */
2054 	if (actual_count > 0) {
2055 		u64 runtime = ktime_to_ns(ktime_sub(ktime_get(), start));
2056 		u64 avg;
2057 
2058 		/*
2059 		 * We weigh the current average higher than our current runtime
2060 		 * to avoid large swings in the average.
2061 		 */
2062 		spin_lock(&delayed_refs->lock);
2063 		avg = fs_info->avg_delayed_ref_runtime * 3 + runtime;
2064 		fs_info->avg_delayed_ref_runtime = avg >> 2;	/* div by 4 */
2065 		spin_unlock(&delayed_refs->lock);
2066 	}
2067 	return 0;
2068 }
2069 
2070 #ifdef SCRAMBLE_DELAYED_REFS
2071 /*
2072  * Normally delayed refs get processed in ascending bytenr order. This
2073  * correlates in most cases to the order added. To expose dependencies on this
2074  * order, we start to process the tree in the middle instead of the beginning
2075  */
2076 static u64 find_middle(struct rb_root *root)
2077 {
2078 	struct rb_node *n = root->rb_node;
2079 	struct btrfs_delayed_ref_node *entry;
2080 	int alt = 1;
2081 	u64 middle;
2082 	u64 first = 0, last = 0;
2083 
2084 	n = rb_first(root);
2085 	if (n) {
2086 		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2087 		first = entry->bytenr;
2088 	}
2089 	n = rb_last(root);
2090 	if (n) {
2091 		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2092 		last = entry->bytenr;
2093 	}
2094 	n = root->rb_node;
2095 
2096 	while (n) {
2097 		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2098 		WARN_ON(!entry->in_tree);
2099 
2100 		middle = entry->bytenr;
2101 
2102 		if (alt)
2103 			n = n->rb_left;
2104 		else
2105 			n = n->rb_right;
2106 
2107 		alt = 1 - alt;
2108 	}
2109 	return middle;
2110 }
2111 #endif
2112 
2113 /*
2114  * this starts processing the delayed reference count updates and
2115  * extent insertions we have queued up so far.  count can be
2116  * 0, which means to process everything in the tree at the start
2117  * of the run (but not newly added entries), or it can be some target
2118  * number you'd like to process.
2119  *
2120  * Returns 0 on success or if called with an aborted transaction
2121  * Returns <0 on error and aborts the transaction
2122  */
2123 int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
2124 			   unsigned long count)
2125 {
2126 	struct btrfs_fs_info *fs_info = trans->fs_info;
2127 	struct rb_node *node;
2128 	struct btrfs_delayed_ref_root *delayed_refs;
2129 	struct btrfs_delayed_ref_head *head;
2130 	int ret;
2131 	int run_all = count == (unsigned long)-1;
2132 
2133 	/* We'll clean this up in btrfs_cleanup_transaction */
2134 	if (TRANS_ABORTED(trans))
2135 		return 0;
2136 
2137 	if (test_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags))
2138 		return 0;
2139 
2140 	delayed_refs = &trans->transaction->delayed_refs;
2141 	if (count == 0)
2142 		count = delayed_refs->num_heads_ready;
2143 
2144 again:
2145 #ifdef SCRAMBLE_DELAYED_REFS
2146 	delayed_refs->run_delayed_start = find_middle(&delayed_refs->root);
2147 #endif
2148 	ret = __btrfs_run_delayed_refs(trans, count);
2149 	if (ret < 0) {
2150 		btrfs_abort_transaction(trans, ret);
2151 		return ret;
2152 	}
2153 
2154 	if (run_all) {
2155 		btrfs_create_pending_block_groups(trans);
2156 
2157 		spin_lock(&delayed_refs->lock);
2158 		node = rb_first_cached(&delayed_refs->href_root);
2159 		if (!node) {
2160 			spin_unlock(&delayed_refs->lock);
2161 			goto out;
2162 		}
2163 		head = rb_entry(node, struct btrfs_delayed_ref_head,
2164 				href_node);
2165 		refcount_inc(&head->refs);
2166 		spin_unlock(&delayed_refs->lock);
2167 
2168 		/* Mutex was contended, block until it's released and retry. */
2169 		mutex_lock(&head->mutex);
2170 		mutex_unlock(&head->mutex);
2171 
2172 		btrfs_put_delayed_ref_head(head);
2173 		cond_resched();
2174 		goto again;
2175 	}
2176 out:
2177 	return 0;
2178 }
2179 
2180 int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
2181 				struct extent_buffer *eb, u64 flags,
2182 				int level, int is_data)
2183 {
2184 	struct btrfs_delayed_extent_op *extent_op;
2185 	int ret;
2186 
2187 	extent_op = btrfs_alloc_delayed_extent_op();
2188 	if (!extent_op)
2189 		return -ENOMEM;
2190 
2191 	extent_op->flags_to_set = flags;
2192 	extent_op->update_flags = true;
2193 	extent_op->update_key = false;
2194 	extent_op->is_data = is_data ? true : false;
2195 	extent_op->level = level;
2196 
2197 	ret = btrfs_add_delayed_extent_op(trans, eb->start, eb->len, extent_op);
2198 	if (ret)
2199 		btrfs_free_delayed_extent_op(extent_op);
2200 	return ret;
2201 }
2202 
2203 static noinline int check_delayed_ref(struct btrfs_root *root,
2204 				      struct btrfs_path *path,
2205 				      u64 objectid, u64 offset, u64 bytenr)
2206 {
2207 	struct btrfs_delayed_ref_head *head;
2208 	struct btrfs_delayed_ref_node *ref;
2209 	struct btrfs_delayed_data_ref *data_ref;
2210 	struct btrfs_delayed_ref_root *delayed_refs;
2211 	struct btrfs_transaction *cur_trans;
2212 	struct rb_node *node;
2213 	int ret = 0;
2214 
2215 	spin_lock(&root->fs_info->trans_lock);
2216 	cur_trans = root->fs_info->running_transaction;
2217 	if (cur_trans)
2218 		refcount_inc(&cur_trans->use_count);
2219 	spin_unlock(&root->fs_info->trans_lock);
2220 	if (!cur_trans)
2221 		return 0;
2222 
2223 	delayed_refs = &cur_trans->delayed_refs;
2224 	spin_lock(&delayed_refs->lock);
2225 	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
2226 	if (!head) {
2227 		spin_unlock(&delayed_refs->lock);
2228 		btrfs_put_transaction(cur_trans);
2229 		return 0;
2230 	}
2231 
2232 	if (!mutex_trylock(&head->mutex)) {
2233 		refcount_inc(&head->refs);
2234 		spin_unlock(&delayed_refs->lock);
2235 
2236 		btrfs_release_path(path);
2237 
2238 		/*
2239 		 * Mutex was contended, block until it's released and let
2240 		 * caller try again
2241 		 */
2242 		mutex_lock(&head->mutex);
2243 		mutex_unlock(&head->mutex);
2244 		btrfs_put_delayed_ref_head(head);
2245 		btrfs_put_transaction(cur_trans);
2246 		return -EAGAIN;
2247 	}
2248 	spin_unlock(&delayed_refs->lock);
2249 
2250 	spin_lock(&head->lock);
2251 	/*
2252 	 * XXX: We should replace this with a proper search function in the
2253 	 * future.
2254 	 */
2255 	for (node = rb_first_cached(&head->ref_tree); node;
2256 	     node = rb_next(node)) {
2257 		ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
2258 		/* If it's a shared ref we know a cross reference exists */
2259 		if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) {
2260 			ret = 1;
2261 			break;
2262 		}
2263 
2264 		data_ref = btrfs_delayed_node_to_data_ref(ref);
2265 
2266 		/*
2267 		 * If our ref doesn't match the one we're currently looking at
2268 		 * then we have a cross reference.
2269 		 */
2270 		if (data_ref->root != root->root_key.objectid ||
2271 		    data_ref->objectid != objectid ||
2272 		    data_ref->offset != offset) {
2273 			ret = 1;
2274 			break;
2275 		}
2276 	}
2277 	spin_unlock(&head->lock);
2278 	mutex_unlock(&head->mutex);
2279 	btrfs_put_transaction(cur_trans);
2280 	return ret;
2281 }
2282 
2283 static noinline int check_committed_ref(struct btrfs_root *root,
2284 					struct btrfs_path *path,
2285 					u64 objectid, u64 offset, u64 bytenr,
2286 					bool strict)
2287 {
2288 	struct btrfs_fs_info *fs_info = root->fs_info;
2289 	struct btrfs_root *extent_root = fs_info->extent_root;
2290 	struct extent_buffer *leaf;
2291 	struct btrfs_extent_data_ref *ref;
2292 	struct btrfs_extent_inline_ref *iref;
2293 	struct btrfs_extent_item *ei;
2294 	struct btrfs_key key;
2295 	u32 item_size;
2296 	int type;
2297 	int ret;
2298 
2299 	key.objectid = bytenr;
2300 	key.offset = (u64)-1;
2301 	key.type = BTRFS_EXTENT_ITEM_KEY;
2302 
2303 	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2304 	if (ret < 0)
2305 		goto out;
2306 	BUG_ON(ret == 0); /* Corruption */
2307 
2308 	ret = -ENOENT;
2309 	if (path->slots[0] == 0)
2310 		goto out;
2311 
2312 	path->slots[0]--;
2313 	leaf = path->nodes[0];
2314 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2315 
2316 	if (key.objectid != bytenr || key.type != BTRFS_EXTENT_ITEM_KEY)
2317 		goto out;
2318 
2319 	ret = 1;
2320 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2321 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
2322 
2323 	/* If extent item has more than 1 inline ref then it's shared */
2324 	if (item_size != sizeof(*ei) +
2325 	    btrfs_extent_inline_ref_size(BTRFS_EXTENT_DATA_REF_KEY))
2326 		goto out;
2327 
2328 	/*
2329 	 * If extent created before last snapshot => it's shared unless the
2330 	 * snapshot has been deleted. Use the heuristic if strict is false.
2331 	 */
2332 	if (!strict &&
2333 	    (btrfs_extent_generation(leaf, ei) <=
2334 	     btrfs_root_last_snapshot(&root->root_item)))
2335 		goto out;
2336 
2337 	iref = (struct btrfs_extent_inline_ref *)(ei + 1);
2338 
2339 	/* If this extent has SHARED_DATA_REF then it's shared */
2340 	type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_DATA);
2341 	if (type != BTRFS_EXTENT_DATA_REF_KEY)
2342 		goto out;
2343 
2344 	ref = (struct btrfs_extent_data_ref *)(&iref->offset);
2345 	if (btrfs_extent_refs(leaf, ei) !=
2346 	    btrfs_extent_data_ref_count(leaf, ref) ||
2347 	    btrfs_extent_data_ref_root(leaf, ref) !=
2348 	    root->root_key.objectid ||
2349 	    btrfs_extent_data_ref_objectid(leaf, ref) != objectid ||
2350 	    btrfs_extent_data_ref_offset(leaf, ref) != offset)
2351 		goto out;
2352 
2353 	ret = 0;
2354 out:
2355 	return ret;
2356 }
2357 
2358 int btrfs_cross_ref_exist(struct btrfs_root *root, u64 objectid, u64 offset,
2359 			  u64 bytenr, bool strict)
2360 {
2361 	struct btrfs_path *path;
2362 	int ret;
2363 
2364 	path = btrfs_alloc_path();
2365 	if (!path)
2366 		return -ENOMEM;
2367 
2368 	do {
2369 		ret = check_committed_ref(root, path, objectid,
2370 					  offset, bytenr, strict);
2371 		if (ret && ret != -ENOENT)
2372 			goto out;
2373 
2374 		ret = check_delayed_ref(root, path, objectid, offset, bytenr);
2375 	} while (ret == -EAGAIN);
2376 
2377 out:
2378 	btrfs_free_path(path);
2379 	if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
2380 		WARN_ON(ret > 0);
2381 	return ret;
2382 }
2383 
2384 static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
2385 			   struct btrfs_root *root,
2386 			   struct extent_buffer *buf,
2387 			   int full_backref, int inc)
2388 {
2389 	struct btrfs_fs_info *fs_info = root->fs_info;
2390 	u64 bytenr;
2391 	u64 num_bytes;
2392 	u64 parent;
2393 	u64 ref_root;
2394 	u32 nritems;
2395 	struct btrfs_key key;
2396 	struct btrfs_file_extent_item *fi;
2397 	struct btrfs_ref generic_ref = { 0 };
2398 	bool for_reloc = btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC);
2399 	int i;
2400 	int action;
2401 	int level;
2402 	int ret = 0;
2403 
2404 	if (btrfs_is_testing(fs_info))
2405 		return 0;
2406 
2407 	ref_root = btrfs_header_owner(buf);
2408 	nritems = btrfs_header_nritems(buf);
2409 	level = btrfs_header_level(buf);
2410 
2411 	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && level == 0)
2412 		return 0;
2413 
2414 	if (full_backref)
2415 		parent = buf->start;
2416 	else
2417 		parent = 0;
2418 	if (inc)
2419 		action = BTRFS_ADD_DELAYED_REF;
2420 	else
2421 		action = BTRFS_DROP_DELAYED_REF;
2422 
2423 	for (i = 0; i < nritems; i++) {
2424 		if (level == 0) {
2425 			btrfs_item_key_to_cpu(buf, &key, i);
2426 			if (key.type != BTRFS_EXTENT_DATA_KEY)
2427 				continue;
2428 			fi = btrfs_item_ptr(buf, i,
2429 					    struct btrfs_file_extent_item);
2430 			if (btrfs_file_extent_type(buf, fi) ==
2431 			    BTRFS_FILE_EXTENT_INLINE)
2432 				continue;
2433 			bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
2434 			if (bytenr == 0)
2435 				continue;
2436 
2437 			num_bytes = btrfs_file_extent_disk_num_bytes(buf, fi);
2438 			key.offset -= btrfs_file_extent_offset(buf, fi);
2439 			btrfs_init_generic_ref(&generic_ref, action, bytenr,
2440 					       num_bytes, parent);
2441 			generic_ref.real_root = root->root_key.objectid;
2442 			btrfs_init_data_ref(&generic_ref, ref_root, key.objectid,
2443 					    key.offset);
2444 			generic_ref.skip_qgroup = for_reloc;
2445 			if (inc)
2446 				ret = btrfs_inc_extent_ref(trans, &generic_ref);
2447 			else
2448 				ret = btrfs_free_extent(trans, &generic_ref);
2449 			if (ret)
2450 				goto fail;
2451 		} else {
2452 			bytenr = btrfs_node_blockptr(buf, i);
2453 			num_bytes = fs_info->nodesize;
2454 			btrfs_init_generic_ref(&generic_ref, action, bytenr,
2455 					       num_bytes, parent);
2456 			generic_ref.real_root = root->root_key.objectid;
2457 			btrfs_init_tree_ref(&generic_ref, level - 1, ref_root);
2458 			generic_ref.skip_qgroup = for_reloc;
2459 			if (inc)
2460 				ret = btrfs_inc_extent_ref(trans, &generic_ref);
2461 			else
2462 				ret = btrfs_free_extent(trans, &generic_ref);
2463 			if (ret)
2464 				goto fail;
2465 		}
2466 	}
2467 	return 0;
2468 fail:
2469 	return ret;
2470 }
2471 
2472 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2473 		  struct extent_buffer *buf, int full_backref)
2474 {
2475 	return __btrfs_mod_ref(trans, root, buf, full_backref, 1);
2476 }
2477 
2478 int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2479 		  struct extent_buffer *buf, int full_backref)
2480 {
2481 	return __btrfs_mod_ref(trans, root, buf, full_backref, 0);
2482 }
2483 
2484 static u64 get_alloc_profile_by_root(struct btrfs_root *root, int data)
2485 {
2486 	struct btrfs_fs_info *fs_info = root->fs_info;
2487 	u64 flags;
2488 	u64 ret;
2489 
2490 	if (data)
2491 		flags = BTRFS_BLOCK_GROUP_DATA;
2492 	else if (root == fs_info->chunk_root)
2493 		flags = BTRFS_BLOCK_GROUP_SYSTEM;
2494 	else
2495 		flags = BTRFS_BLOCK_GROUP_METADATA;
2496 
2497 	ret = btrfs_get_alloc_profile(fs_info, flags);
2498 	return ret;
2499 }
2500 
2501 static u64 first_logical_byte(struct btrfs_fs_info *fs_info, u64 search_start)
2502 {
2503 	struct btrfs_block_group *cache;
2504 	u64 bytenr;
2505 
2506 	spin_lock(&fs_info->block_group_cache_lock);
2507 	bytenr = fs_info->first_logical_byte;
2508 	spin_unlock(&fs_info->block_group_cache_lock);
2509 
2510 	if (bytenr < (u64)-1)
2511 		return bytenr;
2512 
2513 	cache = btrfs_lookup_first_block_group(fs_info, search_start);
2514 	if (!cache)
2515 		return 0;
2516 
2517 	bytenr = cache->start;
2518 	btrfs_put_block_group(cache);
2519 
2520 	return bytenr;
2521 }
2522 
2523 static int pin_down_extent(struct btrfs_trans_handle *trans,
2524 			   struct btrfs_block_group *cache,
2525 			   u64 bytenr, u64 num_bytes, int reserved)
2526 {
2527 	struct btrfs_fs_info *fs_info = cache->fs_info;
2528 
2529 	spin_lock(&cache->space_info->lock);
2530 	spin_lock(&cache->lock);
2531 	cache->pinned += num_bytes;
2532 	btrfs_space_info_update_bytes_pinned(fs_info, cache->space_info,
2533 					     num_bytes);
2534 	if (reserved) {
2535 		cache->reserved -= num_bytes;
2536 		cache->space_info->bytes_reserved -= num_bytes;
2537 	}
2538 	spin_unlock(&cache->lock);
2539 	spin_unlock(&cache->space_info->lock);
2540 
2541 	set_extent_dirty(&trans->transaction->pinned_extents, bytenr,
2542 			 bytenr + num_bytes - 1, GFP_NOFS | __GFP_NOFAIL);
2543 	return 0;
2544 }
2545 
2546 int btrfs_pin_extent(struct btrfs_trans_handle *trans,
2547 		     u64 bytenr, u64 num_bytes, int reserved)
2548 {
2549 	struct btrfs_block_group *cache;
2550 
2551 	cache = btrfs_lookup_block_group(trans->fs_info, bytenr);
2552 	BUG_ON(!cache); /* Logic error */
2553 
2554 	pin_down_extent(trans, cache, bytenr, num_bytes, reserved);
2555 
2556 	btrfs_put_block_group(cache);
2557 	return 0;
2558 }
2559 
2560 /*
2561  * this function must be called within transaction
2562  */
2563 int btrfs_pin_extent_for_log_replay(struct btrfs_trans_handle *trans,
2564 				    u64 bytenr, u64 num_bytes)
2565 {
2566 	struct btrfs_block_group *cache;
2567 	int ret;
2568 
2569 	cache = btrfs_lookup_block_group(trans->fs_info, bytenr);
2570 	if (!cache)
2571 		return -EINVAL;
2572 
2573 	/*
2574 	 * pull in the free space cache (if any) so that our pin
2575 	 * removes the free space from the cache.  We have load_only set
2576 	 * to one because the slow code to read in the free extents does check
2577 	 * the pinned extents.
2578 	 */
2579 	btrfs_cache_block_group(cache, 1);
2580 	/*
2581 	 * Make sure we wait until the cache is completely built in case it is
2582 	 * missing or is invalid and therefore needs to be rebuilt.
2583 	 */
2584 	ret = btrfs_wait_block_group_cache_done(cache);
2585 	if (ret)
2586 		goto out;
2587 
2588 	pin_down_extent(trans, cache, bytenr, num_bytes, 0);
2589 
2590 	/* remove us from the free space cache (if we're there at all) */
2591 	ret = btrfs_remove_free_space(cache, bytenr, num_bytes);
2592 out:
2593 	btrfs_put_block_group(cache);
2594 	return ret;
2595 }
2596 
2597 static int __exclude_logged_extent(struct btrfs_fs_info *fs_info,
2598 				   u64 start, u64 num_bytes)
2599 {
2600 	int ret;
2601 	struct btrfs_block_group *block_group;
2602 
2603 	block_group = btrfs_lookup_block_group(fs_info, start);
2604 	if (!block_group)
2605 		return -EINVAL;
2606 
2607 	btrfs_cache_block_group(block_group, 1);
2608 	/*
2609 	 * Make sure we wait until the cache is completely built in case it is
2610 	 * missing or is invalid and therefore needs to be rebuilt.
2611 	 */
2612 	ret = btrfs_wait_block_group_cache_done(block_group);
2613 	if (ret)
2614 		goto out;
2615 
2616 	ret = btrfs_remove_free_space(block_group, start, num_bytes);
2617 out:
2618 	btrfs_put_block_group(block_group);
2619 	return ret;
2620 }
2621 
2622 int btrfs_exclude_logged_extents(struct extent_buffer *eb)
2623 {
2624 	struct btrfs_fs_info *fs_info = eb->fs_info;
2625 	struct btrfs_file_extent_item *item;
2626 	struct btrfs_key key;
2627 	int found_type;
2628 	int i;
2629 	int ret = 0;
2630 
2631 	if (!btrfs_fs_incompat(fs_info, MIXED_GROUPS))
2632 		return 0;
2633 
2634 	for (i = 0; i < btrfs_header_nritems(eb); i++) {
2635 		btrfs_item_key_to_cpu(eb, &key, i);
2636 		if (key.type != BTRFS_EXTENT_DATA_KEY)
2637 			continue;
2638 		item = btrfs_item_ptr(eb, i, struct btrfs_file_extent_item);
2639 		found_type = btrfs_file_extent_type(eb, item);
2640 		if (found_type == BTRFS_FILE_EXTENT_INLINE)
2641 			continue;
2642 		if (btrfs_file_extent_disk_bytenr(eb, item) == 0)
2643 			continue;
2644 		key.objectid = btrfs_file_extent_disk_bytenr(eb, item);
2645 		key.offset = btrfs_file_extent_disk_num_bytes(eb, item);
2646 		ret = __exclude_logged_extent(fs_info, key.objectid, key.offset);
2647 		if (ret)
2648 			break;
2649 	}
2650 
2651 	return ret;
2652 }
2653 
2654 static void
2655 btrfs_inc_block_group_reservations(struct btrfs_block_group *bg)
2656 {
2657 	atomic_inc(&bg->reservations);
2658 }
2659 
2660 /*
2661  * Returns the free cluster for the given space info and sets empty_cluster to
2662  * what it should be based on the mount options.
2663  */
2664 static struct btrfs_free_cluster *
2665 fetch_cluster_info(struct btrfs_fs_info *fs_info,
2666 		   struct btrfs_space_info *space_info, u64 *empty_cluster)
2667 {
2668 	struct btrfs_free_cluster *ret = NULL;
2669 
2670 	*empty_cluster = 0;
2671 	if (btrfs_mixed_space_info(space_info))
2672 		return ret;
2673 
2674 	if (space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
2675 		ret = &fs_info->meta_alloc_cluster;
2676 		if (btrfs_test_opt(fs_info, SSD))
2677 			*empty_cluster = SZ_2M;
2678 		else
2679 			*empty_cluster = SZ_64K;
2680 	} else if ((space_info->flags & BTRFS_BLOCK_GROUP_DATA) &&
2681 		   btrfs_test_opt(fs_info, SSD_SPREAD)) {
2682 		*empty_cluster = SZ_2M;
2683 		ret = &fs_info->data_alloc_cluster;
2684 	}
2685 
2686 	return ret;
2687 }
2688 
2689 static int unpin_extent_range(struct btrfs_fs_info *fs_info,
2690 			      u64 start, u64 end,
2691 			      const bool return_free_space)
2692 {
2693 	struct btrfs_block_group *cache = NULL;
2694 	struct btrfs_space_info *space_info;
2695 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
2696 	struct btrfs_free_cluster *cluster = NULL;
2697 	u64 len;
2698 	u64 total_unpinned = 0;
2699 	u64 empty_cluster = 0;
2700 	bool readonly;
2701 
2702 	while (start <= end) {
2703 		readonly = false;
2704 		if (!cache ||
2705 		    start >= cache->start + cache->length) {
2706 			if (cache)
2707 				btrfs_put_block_group(cache);
2708 			total_unpinned = 0;
2709 			cache = btrfs_lookup_block_group(fs_info, start);
2710 			BUG_ON(!cache); /* Logic error */
2711 
2712 			cluster = fetch_cluster_info(fs_info,
2713 						     cache->space_info,
2714 						     &empty_cluster);
2715 			empty_cluster <<= 1;
2716 		}
2717 
2718 		len = cache->start + cache->length - start;
2719 		len = min(len, end + 1 - start);
2720 
2721 		down_read(&fs_info->commit_root_sem);
2722 		if (start < cache->last_byte_to_unpin && return_free_space) {
2723 			u64 add_len = min(len, cache->last_byte_to_unpin - start);
2724 
2725 			btrfs_add_free_space(cache, start, add_len);
2726 		}
2727 		up_read(&fs_info->commit_root_sem);
2728 
2729 		start += len;
2730 		total_unpinned += len;
2731 		space_info = cache->space_info;
2732 
2733 		/*
2734 		 * If this space cluster has been marked as fragmented and we've
2735 		 * unpinned enough in this block group to potentially allow a
2736 		 * cluster to be created inside of it go ahead and clear the
2737 		 * fragmented check.
2738 		 */
2739 		if (cluster && cluster->fragmented &&
2740 		    total_unpinned > empty_cluster) {
2741 			spin_lock(&cluster->lock);
2742 			cluster->fragmented = 0;
2743 			spin_unlock(&cluster->lock);
2744 		}
2745 
2746 		spin_lock(&space_info->lock);
2747 		spin_lock(&cache->lock);
2748 		cache->pinned -= len;
2749 		btrfs_space_info_update_bytes_pinned(fs_info, space_info, -len);
2750 		space_info->max_extent_size = 0;
2751 		if (cache->ro) {
2752 			space_info->bytes_readonly += len;
2753 			readonly = true;
2754 		} else if (btrfs_is_zoned(fs_info)) {
2755 			/* Need reset before reusing in a zoned block group */
2756 			space_info->bytes_zone_unusable += len;
2757 			readonly = true;
2758 		}
2759 		spin_unlock(&cache->lock);
2760 		if (!readonly && return_free_space &&
2761 		    global_rsv->space_info == space_info) {
2762 			u64 to_add = len;
2763 
2764 			spin_lock(&global_rsv->lock);
2765 			if (!global_rsv->full) {
2766 				to_add = min(len, global_rsv->size -
2767 					     global_rsv->reserved);
2768 				global_rsv->reserved += to_add;
2769 				btrfs_space_info_update_bytes_may_use(fs_info,
2770 						space_info, to_add);
2771 				if (global_rsv->reserved >= global_rsv->size)
2772 					global_rsv->full = 1;
2773 				len -= to_add;
2774 			}
2775 			spin_unlock(&global_rsv->lock);
2776 		}
2777 		/* Add to any tickets we may have */
2778 		if (!readonly && return_free_space && len)
2779 			btrfs_try_granting_tickets(fs_info, space_info);
2780 		spin_unlock(&space_info->lock);
2781 	}
2782 
2783 	if (cache)
2784 		btrfs_put_block_group(cache);
2785 	return 0;
2786 }
2787 
2788 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
2789 {
2790 	struct btrfs_fs_info *fs_info = trans->fs_info;
2791 	struct btrfs_block_group *block_group, *tmp;
2792 	struct list_head *deleted_bgs;
2793 	struct extent_io_tree *unpin;
2794 	u64 start;
2795 	u64 end;
2796 	int ret;
2797 
2798 	unpin = &trans->transaction->pinned_extents;
2799 
2800 	while (!TRANS_ABORTED(trans)) {
2801 		struct extent_state *cached_state = NULL;
2802 
2803 		mutex_lock(&fs_info->unused_bg_unpin_mutex);
2804 		ret = find_first_extent_bit(unpin, 0, &start, &end,
2805 					    EXTENT_DIRTY, &cached_state);
2806 		if (ret) {
2807 			mutex_unlock(&fs_info->unused_bg_unpin_mutex);
2808 			break;
2809 		}
2810 
2811 		if (btrfs_test_opt(fs_info, DISCARD_SYNC))
2812 			ret = btrfs_discard_extent(fs_info, start,
2813 						   end + 1 - start, NULL);
2814 
2815 		clear_extent_dirty(unpin, start, end, &cached_state);
2816 		unpin_extent_range(fs_info, start, end, true);
2817 		mutex_unlock(&fs_info->unused_bg_unpin_mutex);
2818 		free_extent_state(cached_state);
2819 		cond_resched();
2820 	}
2821 
2822 	if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
2823 		btrfs_discard_calc_delay(&fs_info->discard_ctl);
2824 		btrfs_discard_schedule_work(&fs_info->discard_ctl, true);
2825 	}
2826 
2827 	/*
2828 	 * Transaction is finished.  We don't need the lock anymore.  We
2829 	 * do need to clean up the block groups in case of a transaction
2830 	 * abort.
2831 	 */
2832 	deleted_bgs = &trans->transaction->deleted_bgs;
2833 	list_for_each_entry_safe(block_group, tmp, deleted_bgs, bg_list) {
2834 		u64 trimmed = 0;
2835 
2836 		ret = -EROFS;
2837 		if (!TRANS_ABORTED(trans))
2838 			ret = btrfs_discard_extent(fs_info,
2839 						   block_group->start,
2840 						   block_group->length,
2841 						   &trimmed);
2842 
2843 		list_del_init(&block_group->bg_list);
2844 		btrfs_unfreeze_block_group(block_group);
2845 		btrfs_put_block_group(block_group);
2846 
2847 		if (ret) {
2848 			const char *errstr = btrfs_decode_error(ret);
2849 			btrfs_warn(fs_info,
2850 			   "discard failed while removing blockgroup: errno=%d %s",
2851 				   ret, errstr);
2852 		}
2853 	}
2854 
2855 	return 0;
2856 }
2857 
2858 /*
2859  * Drop one or more refs of @node.
2860  *
2861  * 1. Locate the extent refs.
2862  *    It's either inline in EXTENT/METADATA_ITEM or in keyed SHARED_* item.
2863  *    Locate it, then reduce the refs number or remove the ref line completely.
2864  *
2865  * 2. Update the refs count in EXTENT/METADATA_ITEM
2866  *
2867  * Inline backref case:
2868  *
2869  * in extent tree we have:
2870  *
2871  * 	item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 16201 itemsize 82
2872  *		refs 2 gen 6 flags DATA
2873  *		extent data backref root FS_TREE objectid 258 offset 0 count 1
2874  *		extent data backref root FS_TREE objectid 257 offset 0 count 1
2875  *
2876  * This function gets called with:
2877  *
2878  *    node->bytenr = 13631488
2879  *    node->num_bytes = 1048576
2880  *    root_objectid = FS_TREE
2881  *    owner_objectid = 257
2882  *    owner_offset = 0
2883  *    refs_to_drop = 1
2884  *
2885  * Then we should get some like:
2886  *
2887  * 	item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 16201 itemsize 82
2888  *		refs 1 gen 6 flags DATA
2889  *		extent data backref root FS_TREE objectid 258 offset 0 count 1
2890  *
2891  * Keyed backref case:
2892  *
2893  * in extent tree we have:
2894  *
2895  *	item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 3971 itemsize 24
2896  *		refs 754 gen 6 flags DATA
2897  *	[...]
2898  *	item 2 key (13631488 EXTENT_DATA_REF <HASH>) itemoff 3915 itemsize 28
2899  *		extent data backref root FS_TREE objectid 866 offset 0 count 1
2900  *
2901  * This function get called with:
2902  *
2903  *    node->bytenr = 13631488
2904  *    node->num_bytes = 1048576
2905  *    root_objectid = FS_TREE
2906  *    owner_objectid = 866
2907  *    owner_offset = 0
2908  *    refs_to_drop = 1
2909  *
2910  * Then we should get some like:
2911  *
2912  *	item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 3971 itemsize 24
2913  *		refs 753 gen 6 flags DATA
2914  *
2915  * And that (13631488 EXTENT_DATA_REF <HASH>) gets removed.
2916  */
2917 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
2918 			       struct btrfs_delayed_ref_node *node, u64 parent,
2919 			       u64 root_objectid, u64 owner_objectid,
2920 			       u64 owner_offset, int refs_to_drop,
2921 			       struct btrfs_delayed_extent_op *extent_op)
2922 {
2923 	struct btrfs_fs_info *info = trans->fs_info;
2924 	struct btrfs_key key;
2925 	struct btrfs_path *path;
2926 	struct btrfs_root *extent_root = info->extent_root;
2927 	struct extent_buffer *leaf;
2928 	struct btrfs_extent_item *ei;
2929 	struct btrfs_extent_inline_ref *iref;
2930 	int ret;
2931 	int is_data;
2932 	int extent_slot = 0;
2933 	int found_extent = 0;
2934 	int num_to_del = 1;
2935 	u32 item_size;
2936 	u64 refs;
2937 	u64 bytenr = node->bytenr;
2938 	u64 num_bytes = node->num_bytes;
2939 	int last_ref = 0;
2940 	bool skinny_metadata = btrfs_fs_incompat(info, SKINNY_METADATA);
2941 
2942 	path = btrfs_alloc_path();
2943 	if (!path)
2944 		return -ENOMEM;
2945 
2946 	is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
2947 
2948 	if (!is_data && refs_to_drop != 1) {
2949 		btrfs_crit(info,
2950 "invalid refs_to_drop, dropping more than 1 refs for tree block %llu refs_to_drop %u",
2951 			   node->bytenr, refs_to_drop);
2952 		ret = -EINVAL;
2953 		btrfs_abort_transaction(trans, ret);
2954 		goto out;
2955 	}
2956 
2957 	if (is_data)
2958 		skinny_metadata = false;
2959 
2960 	ret = lookup_extent_backref(trans, path, &iref, bytenr, num_bytes,
2961 				    parent, root_objectid, owner_objectid,
2962 				    owner_offset);
2963 	if (ret == 0) {
2964 		/*
2965 		 * Either the inline backref or the SHARED_DATA_REF/
2966 		 * SHARED_BLOCK_REF is found
2967 		 *
2968 		 * Here is a quick path to locate EXTENT/METADATA_ITEM.
2969 		 * It's possible the EXTENT/METADATA_ITEM is near current slot.
2970 		 */
2971 		extent_slot = path->slots[0];
2972 		while (extent_slot >= 0) {
2973 			btrfs_item_key_to_cpu(path->nodes[0], &key,
2974 					      extent_slot);
2975 			if (key.objectid != bytenr)
2976 				break;
2977 			if (key.type == BTRFS_EXTENT_ITEM_KEY &&
2978 			    key.offset == num_bytes) {
2979 				found_extent = 1;
2980 				break;
2981 			}
2982 			if (key.type == BTRFS_METADATA_ITEM_KEY &&
2983 			    key.offset == owner_objectid) {
2984 				found_extent = 1;
2985 				break;
2986 			}
2987 
2988 			/* Quick path didn't find the EXTEMT/METADATA_ITEM */
2989 			if (path->slots[0] - extent_slot > 5)
2990 				break;
2991 			extent_slot--;
2992 		}
2993 
2994 		if (!found_extent) {
2995 			if (iref) {
2996 				btrfs_crit(info,
2997 "invalid iref, no EXTENT/METADATA_ITEM found but has inline extent ref");
2998 				btrfs_abort_transaction(trans, -EUCLEAN);
2999 				goto err_dump;
3000 			}
3001 			/* Must be SHARED_* item, remove the backref first */
3002 			ret = remove_extent_backref(trans, path, NULL,
3003 						    refs_to_drop,
3004 						    is_data, &last_ref);
3005 			if (ret) {
3006 				btrfs_abort_transaction(trans, ret);
3007 				goto out;
3008 			}
3009 			btrfs_release_path(path);
3010 
3011 			/* Slow path to locate EXTENT/METADATA_ITEM */
3012 			key.objectid = bytenr;
3013 			key.type = BTRFS_EXTENT_ITEM_KEY;
3014 			key.offset = num_bytes;
3015 
3016 			if (!is_data && skinny_metadata) {
3017 				key.type = BTRFS_METADATA_ITEM_KEY;
3018 				key.offset = owner_objectid;
3019 			}
3020 
3021 			ret = btrfs_search_slot(trans, extent_root,
3022 						&key, path, -1, 1);
3023 			if (ret > 0 && skinny_metadata && path->slots[0]) {
3024 				/*
3025 				 * Couldn't find our skinny metadata item,
3026 				 * see if we have ye olde extent item.
3027 				 */
3028 				path->slots[0]--;
3029 				btrfs_item_key_to_cpu(path->nodes[0], &key,
3030 						      path->slots[0]);
3031 				if (key.objectid == bytenr &&
3032 				    key.type == BTRFS_EXTENT_ITEM_KEY &&
3033 				    key.offset == num_bytes)
3034 					ret = 0;
3035 			}
3036 
3037 			if (ret > 0 && skinny_metadata) {
3038 				skinny_metadata = false;
3039 				key.objectid = bytenr;
3040 				key.type = BTRFS_EXTENT_ITEM_KEY;
3041 				key.offset = num_bytes;
3042 				btrfs_release_path(path);
3043 				ret = btrfs_search_slot(trans, extent_root,
3044 							&key, path, -1, 1);
3045 			}
3046 
3047 			if (ret) {
3048 				btrfs_err(info,
3049 					  "umm, got %d back from search, was looking for %llu",
3050 					  ret, bytenr);
3051 				if (ret > 0)
3052 					btrfs_print_leaf(path->nodes[0]);
3053 			}
3054 			if (ret < 0) {
3055 				btrfs_abort_transaction(trans, ret);
3056 				goto out;
3057 			}
3058 			extent_slot = path->slots[0];
3059 		}
3060 	} else if (WARN_ON(ret == -ENOENT)) {
3061 		btrfs_print_leaf(path->nodes[0]);
3062 		btrfs_err(info,
3063 			"unable to find ref byte nr %llu parent %llu root %llu  owner %llu offset %llu",
3064 			bytenr, parent, root_objectid, owner_objectid,
3065 			owner_offset);
3066 		btrfs_abort_transaction(trans, ret);
3067 		goto out;
3068 	} else {
3069 		btrfs_abort_transaction(trans, ret);
3070 		goto out;
3071 	}
3072 
3073 	leaf = path->nodes[0];
3074 	item_size = btrfs_item_size_nr(leaf, extent_slot);
3075 	if (unlikely(item_size < sizeof(*ei))) {
3076 		ret = -EINVAL;
3077 		btrfs_print_v0_err(info);
3078 		btrfs_abort_transaction(trans, ret);
3079 		goto out;
3080 	}
3081 	ei = btrfs_item_ptr(leaf, extent_slot,
3082 			    struct btrfs_extent_item);
3083 	if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID &&
3084 	    key.type == BTRFS_EXTENT_ITEM_KEY) {
3085 		struct btrfs_tree_block_info *bi;
3086 		if (item_size < sizeof(*ei) + sizeof(*bi)) {
3087 			btrfs_crit(info,
3088 "invalid extent item size for key (%llu, %u, %llu) owner %llu, has %u expect >= %zu",
3089 				   key.objectid, key.type, key.offset,
3090 				   owner_objectid, item_size,
3091 				   sizeof(*ei) + sizeof(*bi));
3092 			btrfs_abort_transaction(trans, -EUCLEAN);
3093 			goto err_dump;
3094 		}
3095 		bi = (struct btrfs_tree_block_info *)(ei + 1);
3096 		WARN_ON(owner_objectid != btrfs_tree_block_level(leaf, bi));
3097 	}
3098 
3099 	refs = btrfs_extent_refs(leaf, ei);
3100 	if (refs < refs_to_drop) {
3101 		btrfs_crit(info,
3102 		"trying to drop %d refs but we only have %llu for bytenr %llu",
3103 			  refs_to_drop, refs, bytenr);
3104 		btrfs_abort_transaction(trans, -EUCLEAN);
3105 		goto err_dump;
3106 	}
3107 	refs -= refs_to_drop;
3108 
3109 	if (refs > 0) {
3110 		if (extent_op)
3111 			__run_delayed_extent_op(extent_op, leaf, ei);
3112 		/*
3113 		 * In the case of inline back ref, reference count will
3114 		 * be updated by remove_extent_backref
3115 		 */
3116 		if (iref) {
3117 			if (!found_extent) {
3118 				btrfs_crit(info,
3119 "invalid iref, got inlined extent ref but no EXTENT/METADATA_ITEM found");
3120 				btrfs_abort_transaction(trans, -EUCLEAN);
3121 				goto err_dump;
3122 			}
3123 		} else {
3124 			btrfs_set_extent_refs(leaf, ei, refs);
3125 			btrfs_mark_buffer_dirty(leaf);
3126 		}
3127 		if (found_extent) {
3128 			ret = remove_extent_backref(trans, path, iref,
3129 						    refs_to_drop, is_data,
3130 						    &last_ref);
3131 			if (ret) {
3132 				btrfs_abort_transaction(trans, ret);
3133 				goto out;
3134 			}
3135 		}
3136 	} else {
3137 		/* In this branch refs == 1 */
3138 		if (found_extent) {
3139 			if (is_data && refs_to_drop !=
3140 			    extent_data_ref_count(path, iref)) {
3141 				btrfs_crit(info,
3142 		"invalid refs_to_drop, current refs %u refs_to_drop %u",
3143 					   extent_data_ref_count(path, iref),
3144 					   refs_to_drop);
3145 				btrfs_abort_transaction(trans, -EUCLEAN);
3146 				goto err_dump;
3147 			}
3148 			if (iref) {
3149 				if (path->slots[0] != extent_slot) {
3150 					btrfs_crit(info,
3151 "invalid iref, extent item key (%llu %u %llu) doesn't have wanted iref",
3152 						   key.objectid, key.type,
3153 						   key.offset);
3154 					btrfs_abort_transaction(trans, -EUCLEAN);
3155 					goto err_dump;
3156 				}
3157 			} else {
3158 				/*
3159 				 * No inline ref, we must be at SHARED_* item,
3160 				 * And it's single ref, it must be:
3161 				 * |	extent_slot	  ||extent_slot + 1|
3162 				 * [ EXTENT/METADATA_ITEM ][ SHARED_* ITEM ]
3163 				 */
3164 				if (path->slots[0] != extent_slot + 1) {
3165 					btrfs_crit(info,
3166 	"invalid SHARED_* item, previous item is not EXTENT/METADATA_ITEM");
3167 					btrfs_abort_transaction(trans, -EUCLEAN);
3168 					goto err_dump;
3169 				}
3170 				path->slots[0] = extent_slot;
3171 				num_to_del = 2;
3172 			}
3173 		}
3174 
3175 		last_ref = 1;
3176 		ret = btrfs_del_items(trans, extent_root, path, path->slots[0],
3177 				      num_to_del);
3178 		if (ret) {
3179 			btrfs_abort_transaction(trans, ret);
3180 			goto out;
3181 		}
3182 		btrfs_release_path(path);
3183 
3184 		if (is_data) {
3185 			ret = btrfs_del_csums(trans, info->csum_root, bytenr,
3186 					      num_bytes);
3187 			if (ret) {
3188 				btrfs_abort_transaction(trans, ret);
3189 				goto out;
3190 			}
3191 		}
3192 
3193 		ret = add_to_free_space_tree(trans, bytenr, num_bytes);
3194 		if (ret) {
3195 			btrfs_abort_transaction(trans, ret);
3196 			goto out;
3197 		}
3198 
3199 		ret = btrfs_update_block_group(trans, bytenr, num_bytes, 0);
3200 		if (ret) {
3201 			btrfs_abort_transaction(trans, ret);
3202 			goto out;
3203 		}
3204 	}
3205 	btrfs_release_path(path);
3206 
3207 out:
3208 	btrfs_free_path(path);
3209 	return ret;
3210 err_dump:
3211 	/*
3212 	 * Leaf dump can take up a lot of log buffer, so we only do full leaf
3213 	 * dump for debug build.
3214 	 */
3215 	if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) {
3216 		btrfs_crit(info, "path->slots[0]=%d extent_slot=%d",
3217 			   path->slots[0], extent_slot);
3218 		btrfs_print_leaf(path->nodes[0]);
3219 	}
3220 
3221 	btrfs_free_path(path);
3222 	return -EUCLEAN;
3223 }
3224 
3225 /*
3226  * when we free an block, it is possible (and likely) that we free the last
3227  * delayed ref for that extent as well.  This searches the delayed ref tree for
3228  * a given extent, and if there are no other delayed refs to be processed, it
3229  * removes it from the tree.
3230  */
3231 static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
3232 				      u64 bytenr)
3233 {
3234 	struct btrfs_delayed_ref_head *head;
3235 	struct btrfs_delayed_ref_root *delayed_refs;
3236 	int ret = 0;
3237 
3238 	delayed_refs = &trans->transaction->delayed_refs;
3239 	spin_lock(&delayed_refs->lock);
3240 	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
3241 	if (!head)
3242 		goto out_delayed_unlock;
3243 
3244 	spin_lock(&head->lock);
3245 	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root))
3246 		goto out;
3247 
3248 	if (cleanup_extent_op(head) != NULL)
3249 		goto out;
3250 
3251 	/*
3252 	 * waiting for the lock here would deadlock.  If someone else has it
3253 	 * locked they are already in the process of dropping it anyway
3254 	 */
3255 	if (!mutex_trylock(&head->mutex))
3256 		goto out;
3257 
3258 	btrfs_delete_ref_head(delayed_refs, head);
3259 	head->processing = 0;
3260 
3261 	spin_unlock(&head->lock);
3262 	spin_unlock(&delayed_refs->lock);
3263 
3264 	BUG_ON(head->extent_op);
3265 	if (head->must_insert_reserved)
3266 		ret = 1;
3267 
3268 	btrfs_cleanup_ref_head_accounting(trans->fs_info, delayed_refs, head);
3269 	mutex_unlock(&head->mutex);
3270 	btrfs_put_delayed_ref_head(head);
3271 	return ret;
3272 out:
3273 	spin_unlock(&head->lock);
3274 
3275 out_delayed_unlock:
3276 	spin_unlock(&delayed_refs->lock);
3277 	return 0;
3278 }
3279 
3280 void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
3281 			   struct btrfs_root *root,
3282 			   struct extent_buffer *buf,
3283 			   u64 parent, int last_ref)
3284 {
3285 	struct btrfs_fs_info *fs_info = root->fs_info;
3286 	struct btrfs_ref generic_ref = { 0 };
3287 	int ret;
3288 
3289 	btrfs_init_generic_ref(&generic_ref, BTRFS_DROP_DELAYED_REF,
3290 			       buf->start, buf->len, parent);
3291 	btrfs_init_tree_ref(&generic_ref, btrfs_header_level(buf),
3292 			    root->root_key.objectid);
3293 
3294 	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
3295 		btrfs_ref_tree_mod(fs_info, &generic_ref);
3296 		ret = btrfs_add_delayed_tree_ref(trans, &generic_ref, NULL);
3297 		BUG_ON(ret); /* -ENOMEM */
3298 	}
3299 
3300 	if (last_ref && btrfs_header_generation(buf) == trans->transid) {
3301 		struct btrfs_block_group *cache;
3302 		bool must_pin = false;
3303 
3304 		if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
3305 			ret = check_ref_cleanup(trans, buf->start);
3306 			if (!ret) {
3307 				btrfs_redirty_list_add(trans->transaction, buf);
3308 				goto out;
3309 			}
3310 		}
3311 
3312 		cache = btrfs_lookup_block_group(fs_info, buf->start);
3313 
3314 		if (btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
3315 			pin_down_extent(trans, cache, buf->start, buf->len, 1);
3316 			btrfs_put_block_group(cache);
3317 			goto out;
3318 		}
3319 
3320 		/*
3321 		 * If this is a leaf and there are tree mod log users, we may
3322 		 * have recorded mod log operations that point to this leaf.
3323 		 * So we must make sure no one reuses this leaf's extent before
3324 		 * mod log operations are applied to a node, otherwise after
3325 		 * rewinding a node using the mod log operations we get an
3326 		 * inconsistent btree, as the leaf's extent may now be used as
3327 		 * a node or leaf for another different btree.
3328 		 * We are safe from races here because at this point no other
3329 		 * node or root points to this extent buffer, so if after this
3330 		 * check a new tree mod log user joins, it will not be able to
3331 		 * find a node pointing to this leaf and record operations that
3332 		 * point to this leaf.
3333 		 */
3334 		if (btrfs_header_level(buf) == 0 &&
3335 		    test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
3336 			must_pin = true;
3337 
3338 		if (must_pin || btrfs_is_zoned(fs_info)) {
3339 			btrfs_redirty_list_add(trans->transaction, buf);
3340 			pin_down_extent(trans, cache, buf->start, buf->len, 1);
3341 			btrfs_put_block_group(cache);
3342 			goto out;
3343 		}
3344 
3345 		WARN_ON(test_bit(EXTENT_BUFFER_DIRTY, &buf->bflags));
3346 
3347 		btrfs_add_free_space(cache, buf->start, buf->len);
3348 		btrfs_free_reserved_bytes(cache, buf->len, 0);
3349 		btrfs_put_block_group(cache);
3350 		trace_btrfs_reserved_extent_free(fs_info, buf->start, buf->len);
3351 	}
3352 out:
3353 	if (last_ref) {
3354 		/*
3355 		 * Deleting the buffer, clear the corrupt flag since it doesn't
3356 		 * matter anymore.
3357 		 */
3358 		clear_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags);
3359 	}
3360 }
3361 
3362 /* Can return -ENOMEM */
3363 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_ref *ref)
3364 {
3365 	struct btrfs_fs_info *fs_info = trans->fs_info;
3366 	int ret;
3367 
3368 	if (btrfs_is_testing(fs_info))
3369 		return 0;
3370 
3371 	/*
3372 	 * tree log blocks never actually go into the extent allocation
3373 	 * tree, just update pinning info and exit early.
3374 	 */
3375 	if ((ref->type == BTRFS_REF_METADATA &&
3376 	     ref->tree_ref.root == BTRFS_TREE_LOG_OBJECTID) ||
3377 	    (ref->type == BTRFS_REF_DATA &&
3378 	     ref->data_ref.ref_root == BTRFS_TREE_LOG_OBJECTID)) {
3379 		/* unlocks the pinned mutex */
3380 		btrfs_pin_extent(trans, ref->bytenr, ref->len, 1);
3381 		ret = 0;
3382 	} else if (ref->type == BTRFS_REF_METADATA) {
3383 		ret = btrfs_add_delayed_tree_ref(trans, ref, NULL);
3384 	} else {
3385 		ret = btrfs_add_delayed_data_ref(trans, ref, 0);
3386 	}
3387 
3388 	if (!((ref->type == BTRFS_REF_METADATA &&
3389 	       ref->tree_ref.root == BTRFS_TREE_LOG_OBJECTID) ||
3390 	      (ref->type == BTRFS_REF_DATA &&
3391 	       ref->data_ref.ref_root == BTRFS_TREE_LOG_OBJECTID)))
3392 		btrfs_ref_tree_mod(fs_info, ref);
3393 
3394 	return ret;
3395 }
3396 
3397 enum btrfs_loop_type {
3398 	LOOP_CACHING_NOWAIT,
3399 	LOOP_CACHING_WAIT,
3400 	LOOP_ALLOC_CHUNK,
3401 	LOOP_NO_EMPTY_SIZE,
3402 };
3403 
3404 static inline void
3405 btrfs_lock_block_group(struct btrfs_block_group *cache,
3406 		       int delalloc)
3407 {
3408 	if (delalloc)
3409 		down_read(&cache->data_rwsem);
3410 }
3411 
3412 static inline void btrfs_grab_block_group(struct btrfs_block_group *cache,
3413 		       int delalloc)
3414 {
3415 	btrfs_get_block_group(cache);
3416 	if (delalloc)
3417 		down_read(&cache->data_rwsem);
3418 }
3419 
3420 static struct btrfs_block_group *btrfs_lock_cluster(
3421 		   struct btrfs_block_group *block_group,
3422 		   struct btrfs_free_cluster *cluster,
3423 		   int delalloc)
3424 	__acquires(&cluster->refill_lock)
3425 {
3426 	struct btrfs_block_group *used_bg = NULL;
3427 
3428 	spin_lock(&cluster->refill_lock);
3429 	while (1) {
3430 		used_bg = cluster->block_group;
3431 		if (!used_bg)
3432 			return NULL;
3433 
3434 		if (used_bg == block_group)
3435 			return used_bg;
3436 
3437 		btrfs_get_block_group(used_bg);
3438 
3439 		if (!delalloc)
3440 			return used_bg;
3441 
3442 		if (down_read_trylock(&used_bg->data_rwsem))
3443 			return used_bg;
3444 
3445 		spin_unlock(&cluster->refill_lock);
3446 
3447 		/* We should only have one-level nested. */
3448 		down_read_nested(&used_bg->data_rwsem, SINGLE_DEPTH_NESTING);
3449 
3450 		spin_lock(&cluster->refill_lock);
3451 		if (used_bg == cluster->block_group)
3452 			return used_bg;
3453 
3454 		up_read(&used_bg->data_rwsem);
3455 		btrfs_put_block_group(used_bg);
3456 	}
3457 }
3458 
3459 static inline void
3460 btrfs_release_block_group(struct btrfs_block_group *cache,
3461 			 int delalloc)
3462 {
3463 	if (delalloc)
3464 		up_read(&cache->data_rwsem);
3465 	btrfs_put_block_group(cache);
3466 }
3467 
3468 enum btrfs_extent_allocation_policy {
3469 	BTRFS_EXTENT_ALLOC_CLUSTERED,
3470 	BTRFS_EXTENT_ALLOC_ZONED,
3471 };
3472 
3473 /*
3474  * Structure used internally for find_free_extent() function.  Wraps needed
3475  * parameters.
3476  */
3477 struct find_free_extent_ctl {
3478 	/* Basic allocation info */
3479 	u64 num_bytes;
3480 	u64 empty_size;
3481 	u64 flags;
3482 	int delalloc;
3483 
3484 	/* Where to start the search inside the bg */
3485 	u64 search_start;
3486 
3487 	/* For clustered allocation */
3488 	u64 empty_cluster;
3489 	struct btrfs_free_cluster *last_ptr;
3490 	bool use_cluster;
3491 
3492 	bool have_caching_bg;
3493 	bool orig_have_caching_bg;
3494 
3495 	/* Allocation is called for tree-log */
3496 	bool for_treelog;
3497 
3498 	/* RAID index, converted from flags */
3499 	int index;
3500 
3501 	/*
3502 	 * Current loop number, check find_free_extent_update_loop() for details
3503 	 */
3504 	int loop;
3505 
3506 	/*
3507 	 * Whether we're refilling a cluster, if true we need to re-search
3508 	 * current block group but don't try to refill the cluster again.
3509 	 */
3510 	bool retry_clustered;
3511 
3512 	/*
3513 	 * Whether we're updating free space cache, if true we need to re-search
3514 	 * current block group but don't try updating free space cache again.
3515 	 */
3516 	bool retry_unclustered;
3517 
3518 	/* If current block group is cached */
3519 	int cached;
3520 
3521 	/* Max contiguous hole found */
3522 	u64 max_extent_size;
3523 
3524 	/* Total free space from free space cache, not always contiguous */
3525 	u64 total_free_space;
3526 
3527 	/* Found result */
3528 	u64 found_offset;
3529 
3530 	/* Hint where to start looking for an empty space */
3531 	u64 hint_byte;
3532 
3533 	/* Allocation policy */
3534 	enum btrfs_extent_allocation_policy policy;
3535 };
3536 
3537 
3538 /*
3539  * Helper function for find_free_extent().
3540  *
3541  * Return -ENOENT to inform caller that we need fallback to unclustered mode.
3542  * Return -EAGAIN to inform caller that we need to re-search this block group
3543  * Return >0 to inform caller that we find nothing
3544  * Return 0 means we have found a location and set ffe_ctl->found_offset.
3545  */
3546 static int find_free_extent_clustered(struct btrfs_block_group *bg,
3547 				      struct find_free_extent_ctl *ffe_ctl,
3548 				      struct btrfs_block_group **cluster_bg_ret)
3549 {
3550 	struct btrfs_block_group *cluster_bg;
3551 	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
3552 	u64 aligned_cluster;
3553 	u64 offset;
3554 	int ret;
3555 
3556 	cluster_bg = btrfs_lock_cluster(bg, last_ptr, ffe_ctl->delalloc);
3557 	if (!cluster_bg)
3558 		goto refill_cluster;
3559 	if (cluster_bg != bg && (cluster_bg->ro ||
3560 	    !block_group_bits(cluster_bg, ffe_ctl->flags)))
3561 		goto release_cluster;
3562 
3563 	offset = btrfs_alloc_from_cluster(cluster_bg, last_ptr,
3564 			ffe_ctl->num_bytes, cluster_bg->start,
3565 			&ffe_ctl->max_extent_size);
3566 	if (offset) {
3567 		/* We have a block, we're done */
3568 		spin_unlock(&last_ptr->refill_lock);
3569 		trace_btrfs_reserve_extent_cluster(cluster_bg,
3570 				ffe_ctl->search_start, ffe_ctl->num_bytes);
3571 		*cluster_bg_ret = cluster_bg;
3572 		ffe_ctl->found_offset = offset;
3573 		return 0;
3574 	}
3575 	WARN_ON(last_ptr->block_group != cluster_bg);
3576 
3577 release_cluster:
3578 	/*
3579 	 * If we are on LOOP_NO_EMPTY_SIZE, we can't set up a new clusters, so
3580 	 * lets just skip it and let the allocator find whatever block it can
3581 	 * find. If we reach this point, we will have tried the cluster
3582 	 * allocator plenty of times and not have found anything, so we are
3583 	 * likely way too fragmented for the clustering stuff to find anything.
3584 	 *
3585 	 * However, if the cluster is taken from the current block group,
3586 	 * release the cluster first, so that we stand a better chance of
3587 	 * succeeding in the unclustered allocation.
3588 	 */
3589 	if (ffe_ctl->loop >= LOOP_NO_EMPTY_SIZE && cluster_bg != bg) {
3590 		spin_unlock(&last_ptr->refill_lock);
3591 		btrfs_release_block_group(cluster_bg, ffe_ctl->delalloc);
3592 		return -ENOENT;
3593 	}
3594 
3595 	/* This cluster didn't work out, free it and start over */
3596 	btrfs_return_cluster_to_free_space(NULL, last_ptr);
3597 
3598 	if (cluster_bg != bg)
3599 		btrfs_release_block_group(cluster_bg, ffe_ctl->delalloc);
3600 
3601 refill_cluster:
3602 	if (ffe_ctl->loop >= LOOP_NO_EMPTY_SIZE) {
3603 		spin_unlock(&last_ptr->refill_lock);
3604 		return -ENOENT;
3605 	}
3606 
3607 	aligned_cluster = max_t(u64,
3608 			ffe_ctl->empty_cluster + ffe_ctl->empty_size,
3609 			bg->full_stripe_len);
3610 	ret = btrfs_find_space_cluster(bg, last_ptr, ffe_ctl->search_start,
3611 			ffe_ctl->num_bytes, aligned_cluster);
3612 	if (ret == 0) {
3613 		/* Now pull our allocation out of this cluster */
3614 		offset = btrfs_alloc_from_cluster(bg, last_ptr,
3615 				ffe_ctl->num_bytes, ffe_ctl->search_start,
3616 				&ffe_ctl->max_extent_size);
3617 		if (offset) {
3618 			/* We found one, proceed */
3619 			spin_unlock(&last_ptr->refill_lock);
3620 			trace_btrfs_reserve_extent_cluster(bg,
3621 					ffe_ctl->search_start,
3622 					ffe_ctl->num_bytes);
3623 			ffe_ctl->found_offset = offset;
3624 			return 0;
3625 		}
3626 	} else if (!ffe_ctl->cached && ffe_ctl->loop > LOOP_CACHING_NOWAIT &&
3627 		   !ffe_ctl->retry_clustered) {
3628 		spin_unlock(&last_ptr->refill_lock);
3629 
3630 		ffe_ctl->retry_clustered = true;
3631 		btrfs_wait_block_group_cache_progress(bg, ffe_ctl->num_bytes +
3632 				ffe_ctl->empty_cluster + ffe_ctl->empty_size);
3633 		return -EAGAIN;
3634 	}
3635 	/*
3636 	 * At this point we either didn't find a cluster or we weren't able to
3637 	 * allocate a block from our cluster.  Free the cluster we've been
3638 	 * trying to use, and go to the next block group.
3639 	 */
3640 	btrfs_return_cluster_to_free_space(NULL, last_ptr);
3641 	spin_unlock(&last_ptr->refill_lock);
3642 	return 1;
3643 }
3644 
3645 /*
3646  * Return >0 to inform caller that we find nothing
3647  * Return 0 when we found an free extent and set ffe_ctrl->found_offset
3648  * Return -EAGAIN to inform caller that we need to re-search this block group
3649  */
3650 static int find_free_extent_unclustered(struct btrfs_block_group *bg,
3651 					struct find_free_extent_ctl *ffe_ctl)
3652 {
3653 	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
3654 	u64 offset;
3655 
3656 	/*
3657 	 * We are doing an unclustered allocation, set the fragmented flag so
3658 	 * we don't bother trying to setup a cluster again until we get more
3659 	 * space.
3660 	 */
3661 	if (unlikely(last_ptr)) {
3662 		spin_lock(&last_ptr->lock);
3663 		last_ptr->fragmented = 1;
3664 		spin_unlock(&last_ptr->lock);
3665 	}
3666 	if (ffe_ctl->cached) {
3667 		struct btrfs_free_space_ctl *free_space_ctl;
3668 
3669 		free_space_ctl = bg->free_space_ctl;
3670 		spin_lock(&free_space_ctl->tree_lock);
3671 		if (free_space_ctl->free_space <
3672 		    ffe_ctl->num_bytes + ffe_ctl->empty_cluster +
3673 		    ffe_ctl->empty_size) {
3674 			ffe_ctl->total_free_space = max_t(u64,
3675 					ffe_ctl->total_free_space,
3676 					free_space_ctl->free_space);
3677 			spin_unlock(&free_space_ctl->tree_lock);
3678 			return 1;
3679 		}
3680 		spin_unlock(&free_space_ctl->tree_lock);
3681 	}
3682 
3683 	offset = btrfs_find_space_for_alloc(bg, ffe_ctl->search_start,
3684 			ffe_ctl->num_bytes, ffe_ctl->empty_size,
3685 			&ffe_ctl->max_extent_size);
3686 
3687 	/*
3688 	 * If we didn't find a chunk, and we haven't failed on this block group
3689 	 * before, and this block group is in the middle of caching and we are
3690 	 * ok with waiting, then go ahead and wait for progress to be made, and
3691 	 * set @retry_unclustered to true.
3692 	 *
3693 	 * If @retry_unclustered is true then we've already waited on this
3694 	 * block group once and should move on to the next block group.
3695 	 */
3696 	if (!offset && !ffe_ctl->retry_unclustered && !ffe_ctl->cached &&
3697 	    ffe_ctl->loop > LOOP_CACHING_NOWAIT) {
3698 		btrfs_wait_block_group_cache_progress(bg, ffe_ctl->num_bytes +
3699 						      ffe_ctl->empty_size);
3700 		ffe_ctl->retry_unclustered = true;
3701 		return -EAGAIN;
3702 	} else if (!offset) {
3703 		return 1;
3704 	}
3705 	ffe_ctl->found_offset = offset;
3706 	return 0;
3707 }
3708 
3709 static int do_allocation_clustered(struct btrfs_block_group *block_group,
3710 				   struct find_free_extent_ctl *ffe_ctl,
3711 				   struct btrfs_block_group **bg_ret)
3712 {
3713 	int ret;
3714 
3715 	/* We want to try and use the cluster allocator, so lets look there */
3716 	if (ffe_ctl->last_ptr && ffe_ctl->use_cluster) {
3717 		ret = find_free_extent_clustered(block_group, ffe_ctl, bg_ret);
3718 		if (ret >= 0 || ret == -EAGAIN)
3719 			return ret;
3720 		/* ret == -ENOENT case falls through */
3721 	}
3722 
3723 	return find_free_extent_unclustered(block_group, ffe_ctl);
3724 }
3725 
3726 /*
3727  * Tree-log block group locking
3728  * ============================
3729  *
3730  * fs_info::treelog_bg_lock protects the fs_info::treelog_bg which
3731  * indicates the starting address of a block group, which is reserved only
3732  * for tree-log metadata.
3733  *
3734  * Lock nesting
3735  * ============
3736  *
3737  * space_info::lock
3738  *   block_group::lock
3739  *     fs_info::treelog_bg_lock
3740  */
3741 
3742 /*
3743  * Simple allocator for sequential-only block group. It only allows sequential
3744  * allocation. No need to play with trees. This function also reserves the
3745  * bytes as in btrfs_add_reserved_bytes.
3746  */
3747 static int do_allocation_zoned(struct btrfs_block_group *block_group,
3748 			       struct find_free_extent_ctl *ffe_ctl,
3749 			       struct btrfs_block_group **bg_ret)
3750 {
3751 	struct btrfs_fs_info *fs_info = block_group->fs_info;
3752 	struct btrfs_space_info *space_info = block_group->space_info;
3753 	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3754 	u64 start = block_group->start;
3755 	u64 num_bytes = ffe_ctl->num_bytes;
3756 	u64 avail;
3757 	u64 bytenr = block_group->start;
3758 	u64 log_bytenr;
3759 	int ret = 0;
3760 	bool skip;
3761 
3762 	ASSERT(btrfs_is_zoned(block_group->fs_info));
3763 
3764 	/*
3765 	 * Do not allow non-tree-log blocks in the dedicated tree-log block
3766 	 * group, and vice versa.
3767 	 */
3768 	spin_lock(&fs_info->treelog_bg_lock);
3769 	log_bytenr = fs_info->treelog_bg;
3770 	skip = log_bytenr && ((ffe_ctl->for_treelog && bytenr != log_bytenr) ||
3771 			      (!ffe_ctl->for_treelog && bytenr == log_bytenr));
3772 	spin_unlock(&fs_info->treelog_bg_lock);
3773 	if (skip)
3774 		return 1;
3775 
3776 	spin_lock(&space_info->lock);
3777 	spin_lock(&block_group->lock);
3778 	spin_lock(&fs_info->treelog_bg_lock);
3779 
3780 	ASSERT(!ffe_ctl->for_treelog ||
3781 	       block_group->start == fs_info->treelog_bg ||
3782 	       fs_info->treelog_bg == 0);
3783 
3784 	if (block_group->ro) {
3785 		ret = 1;
3786 		goto out;
3787 	}
3788 
3789 	/*
3790 	 * Do not allow currently using block group to be tree-log dedicated
3791 	 * block group.
3792 	 */
3793 	if (ffe_ctl->for_treelog && !fs_info->treelog_bg &&
3794 	    (block_group->used || block_group->reserved)) {
3795 		ret = 1;
3796 		goto out;
3797 	}
3798 
3799 	avail = block_group->length - block_group->alloc_offset;
3800 	if (avail < num_bytes) {
3801 		if (ffe_ctl->max_extent_size < avail) {
3802 			/*
3803 			 * With sequential allocator, free space is always
3804 			 * contiguous
3805 			 */
3806 			ffe_ctl->max_extent_size = avail;
3807 			ffe_ctl->total_free_space = avail;
3808 		}
3809 		ret = 1;
3810 		goto out;
3811 	}
3812 
3813 	if (ffe_ctl->for_treelog && !fs_info->treelog_bg)
3814 		fs_info->treelog_bg = block_group->start;
3815 
3816 	ffe_ctl->found_offset = start + block_group->alloc_offset;
3817 	block_group->alloc_offset += num_bytes;
3818 	spin_lock(&ctl->tree_lock);
3819 	ctl->free_space -= num_bytes;
3820 	spin_unlock(&ctl->tree_lock);
3821 
3822 	/*
3823 	 * We do not check if found_offset is aligned to stripesize. The
3824 	 * address is anyway rewritten when using zone append writing.
3825 	 */
3826 
3827 	ffe_ctl->search_start = ffe_ctl->found_offset;
3828 
3829 out:
3830 	if (ret && ffe_ctl->for_treelog)
3831 		fs_info->treelog_bg = 0;
3832 	spin_unlock(&fs_info->treelog_bg_lock);
3833 	spin_unlock(&block_group->lock);
3834 	spin_unlock(&space_info->lock);
3835 	return ret;
3836 }
3837 
3838 static int do_allocation(struct btrfs_block_group *block_group,
3839 			 struct find_free_extent_ctl *ffe_ctl,
3840 			 struct btrfs_block_group **bg_ret)
3841 {
3842 	switch (ffe_ctl->policy) {
3843 	case BTRFS_EXTENT_ALLOC_CLUSTERED:
3844 		return do_allocation_clustered(block_group, ffe_ctl, bg_ret);
3845 	case BTRFS_EXTENT_ALLOC_ZONED:
3846 		return do_allocation_zoned(block_group, ffe_ctl, bg_ret);
3847 	default:
3848 		BUG();
3849 	}
3850 }
3851 
3852 static void release_block_group(struct btrfs_block_group *block_group,
3853 				struct find_free_extent_ctl *ffe_ctl,
3854 				int delalloc)
3855 {
3856 	switch (ffe_ctl->policy) {
3857 	case BTRFS_EXTENT_ALLOC_CLUSTERED:
3858 		ffe_ctl->retry_clustered = false;
3859 		ffe_ctl->retry_unclustered = false;
3860 		break;
3861 	case BTRFS_EXTENT_ALLOC_ZONED:
3862 		/* Nothing to do */
3863 		break;
3864 	default:
3865 		BUG();
3866 	}
3867 
3868 	BUG_ON(btrfs_bg_flags_to_raid_index(block_group->flags) !=
3869 	       ffe_ctl->index);
3870 	btrfs_release_block_group(block_group, delalloc);
3871 }
3872 
3873 static void found_extent_clustered(struct find_free_extent_ctl *ffe_ctl,
3874 				   struct btrfs_key *ins)
3875 {
3876 	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
3877 
3878 	if (!ffe_ctl->use_cluster && last_ptr) {
3879 		spin_lock(&last_ptr->lock);
3880 		last_ptr->window_start = ins->objectid;
3881 		spin_unlock(&last_ptr->lock);
3882 	}
3883 }
3884 
3885 static void found_extent(struct find_free_extent_ctl *ffe_ctl,
3886 			 struct btrfs_key *ins)
3887 {
3888 	switch (ffe_ctl->policy) {
3889 	case BTRFS_EXTENT_ALLOC_CLUSTERED:
3890 		found_extent_clustered(ffe_ctl, ins);
3891 		break;
3892 	case BTRFS_EXTENT_ALLOC_ZONED:
3893 		/* Nothing to do */
3894 		break;
3895 	default:
3896 		BUG();
3897 	}
3898 }
3899 
3900 static int chunk_allocation_failed(struct find_free_extent_ctl *ffe_ctl)
3901 {
3902 	switch (ffe_ctl->policy) {
3903 	case BTRFS_EXTENT_ALLOC_CLUSTERED:
3904 		/*
3905 		 * If we can't allocate a new chunk we've already looped through
3906 		 * at least once, move on to the NO_EMPTY_SIZE case.
3907 		 */
3908 		ffe_ctl->loop = LOOP_NO_EMPTY_SIZE;
3909 		return 0;
3910 	case BTRFS_EXTENT_ALLOC_ZONED:
3911 		/* Give up here */
3912 		return -ENOSPC;
3913 	default:
3914 		BUG();
3915 	}
3916 }
3917 
3918 /*
3919  * Return >0 means caller needs to re-search for free extent
3920  * Return 0 means we have the needed free extent.
3921  * Return <0 means we failed to locate any free extent.
3922  */
3923 static int find_free_extent_update_loop(struct btrfs_fs_info *fs_info,
3924 					struct btrfs_key *ins,
3925 					struct find_free_extent_ctl *ffe_ctl,
3926 					bool full_search)
3927 {
3928 	struct btrfs_root *root = fs_info->extent_root;
3929 	int ret;
3930 
3931 	if ((ffe_ctl->loop == LOOP_CACHING_NOWAIT) &&
3932 	    ffe_ctl->have_caching_bg && !ffe_ctl->orig_have_caching_bg)
3933 		ffe_ctl->orig_have_caching_bg = true;
3934 
3935 	if (!ins->objectid && ffe_ctl->loop >= LOOP_CACHING_WAIT &&
3936 	    ffe_ctl->have_caching_bg)
3937 		return 1;
3938 
3939 	if (!ins->objectid && ++(ffe_ctl->index) < BTRFS_NR_RAID_TYPES)
3940 		return 1;
3941 
3942 	if (ins->objectid) {
3943 		found_extent(ffe_ctl, ins);
3944 		return 0;
3945 	}
3946 
3947 	/*
3948 	 * LOOP_CACHING_NOWAIT, search partially cached block groups, kicking
3949 	 *			caching kthreads as we move along
3950 	 * LOOP_CACHING_WAIT, search everything, and wait if our bg is caching
3951 	 * LOOP_ALLOC_CHUNK, force a chunk allocation and try again
3952 	 * LOOP_NO_EMPTY_SIZE, set empty_size and empty_cluster to 0 and try
3953 	 *		       again
3954 	 */
3955 	if (ffe_ctl->loop < LOOP_NO_EMPTY_SIZE) {
3956 		ffe_ctl->index = 0;
3957 		if (ffe_ctl->loop == LOOP_CACHING_NOWAIT) {
3958 			/*
3959 			 * We want to skip the LOOP_CACHING_WAIT step if we
3960 			 * don't have any uncached bgs and we've already done a
3961 			 * full search through.
3962 			 */
3963 			if (ffe_ctl->orig_have_caching_bg || !full_search)
3964 				ffe_ctl->loop = LOOP_CACHING_WAIT;
3965 			else
3966 				ffe_ctl->loop = LOOP_ALLOC_CHUNK;
3967 		} else {
3968 			ffe_ctl->loop++;
3969 		}
3970 
3971 		if (ffe_ctl->loop == LOOP_ALLOC_CHUNK) {
3972 			struct btrfs_trans_handle *trans;
3973 			int exist = 0;
3974 
3975 			trans = current->journal_info;
3976 			if (trans)
3977 				exist = 1;
3978 			else
3979 				trans = btrfs_join_transaction(root);
3980 
3981 			if (IS_ERR(trans)) {
3982 				ret = PTR_ERR(trans);
3983 				return ret;
3984 			}
3985 
3986 			ret = btrfs_chunk_alloc(trans, ffe_ctl->flags,
3987 						CHUNK_ALLOC_FORCE);
3988 
3989 			/* Do not bail out on ENOSPC since we can do more. */
3990 			if (ret == -ENOSPC)
3991 				ret = chunk_allocation_failed(ffe_ctl);
3992 			else if (ret < 0)
3993 				btrfs_abort_transaction(trans, ret);
3994 			else
3995 				ret = 0;
3996 			if (!exist)
3997 				btrfs_end_transaction(trans);
3998 			if (ret)
3999 				return ret;
4000 		}
4001 
4002 		if (ffe_ctl->loop == LOOP_NO_EMPTY_SIZE) {
4003 			if (ffe_ctl->policy != BTRFS_EXTENT_ALLOC_CLUSTERED)
4004 				return -ENOSPC;
4005 
4006 			/*
4007 			 * Don't loop again if we already have no empty_size and
4008 			 * no empty_cluster.
4009 			 */
4010 			if (ffe_ctl->empty_size == 0 &&
4011 			    ffe_ctl->empty_cluster == 0)
4012 				return -ENOSPC;
4013 			ffe_ctl->empty_size = 0;
4014 			ffe_ctl->empty_cluster = 0;
4015 		}
4016 		return 1;
4017 	}
4018 	return -ENOSPC;
4019 }
4020 
4021 static int prepare_allocation_clustered(struct btrfs_fs_info *fs_info,
4022 					struct find_free_extent_ctl *ffe_ctl,
4023 					struct btrfs_space_info *space_info,
4024 					struct btrfs_key *ins)
4025 {
4026 	/*
4027 	 * If our free space is heavily fragmented we may not be able to make
4028 	 * big contiguous allocations, so instead of doing the expensive search
4029 	 * for free space, simply return ENOSPC with our max_extent_size so we
4030 	 * can go ahead and search for a more manageable chunk.
4031 	 *
4032 	 * If our max_extent_size is large enough for our allocation simply
4033 	 * disable clustering since we will likely not be able to find enough
4034 	 * space to create a cluster and induce latency trying.
4035 	 */
4036 	if (space_info->max_extent_size) {
4037 		spin_lock(&space_info->lock);
4038 		if (space_info->max_extent_size &&
4039 		    ffe_ctl->num_bytes > space_info->max_extent_size) {
4040 			ins->offset = space_info->max_extent_size;
4041 			spin_unlock(&space_info->lock);
4042 			return -ENOSPC;
4043 		} else if (space_info->max_extent_size) {
4044 			ffe_ctl->use_cluster = false;
4045 		}
4046 		spin_unlock(&space_info->lock);
4047 	}
4048 
4049 	ffe_ctl->last_ptr = fetch_cluster_info(fs_info, space_info,
4050 					       &ffe_ctl->empty_cluster);
4051 	if (ffe_ctl->last_ptr) {
4052 		struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
4053 
4054 		spin_lock(&last_ptr->lock);
4055 		if (last_ptr->block_group)
4056 			ffe_ctl->hint_byte = last_ptr->window_start;
4057 		if (last_ptr->fragmented) {
4058 			/*
4059 			 * We still set window_start so we can keep track of the
4060 			 * last place we found an allocation to try and save
4061 			 * some time.
4062 			 */
4063 			ffe_ctl->hint_byte = last_ptr->window_start;
4064 			ffe_ctl->use_cluster = false;
4065 		}
4066 		spin_unlock(&last_ptr->lock);
4067 	}
4068 
4069 	return 0;
4070 }
4071 
4072 static int prepare_allocation(struct btrfs_fs_info *fs_info,
4073 			      struct find_free_extent_ctl *ffe_ctl,
4074 			      struct btrfs_space_info *space_info,
4075 			      struct btrfs_key *ins)
4076 {
4077 	switch (ffe_ctl->policy) {
4078 	case BTRFS_EXTENT_ALLOC_CLUSTERED:
4079 		return prepare_allocation_clustered(fs_info, ffe_ctl,
4080 						    space_info, ins);
4081 	case BTRFS_EXTENT_ALLOC_ZONED:
4082 		if (ffe_ctl->for_treelog) {
4083 			spin_lock(&fs_info->treelog_bg_lock);
4084 			if (fs_info->treelog_bg)
4085 				ffe_ctl->hint_byte = fs_info->treelog_bg;
4086 			spin_unlock(&fs_info->treelog_bg_lock);
4087 		}
4088 		return 0;
4089 	default:
4090 		BUG();
4091 	}
4092 }
4093 
4094 /*
4095  * walks the btree of allocated extents and find a hole of a given size.
4096  * The key ins is changed to record the hole:
4097  * ins->objectid == start position
4098  * ins->flags = BTRFS_EXTENT_ITEM_KEY
4099  * ins->offset == the size of the hole.
4100  * Any available blocks before search_start are skipped.
4101  *
4102  * If there is no suitable free space, we will record the max size of
4103  * the free space extent currently.
4104  *
4105  * The overall logic and call chain:
4106  *
4107  * find_free_extent()
4108  * |- Iterate through all block groups
4109  * |  |- Get a valid block group
4110  * |  |- Try to do clustered allocation in that block group
4111  * |  |- Try to do unclustered allocation in that block group
4112  * |  |- Check if the result is valid
4113  * |  |  |- If valid, then exit
4114  * |  |- Jump to next block group
4115  * |
4116  * |- Push harder to find free extents
4117  *    |- If not found, re-iterate all block groups
4118  */
4119 static noinline int find_free_extent(struct btrfs_root *root,
4120 				u64 ram_bytes, u64 num_bytes, u64 empty_size,
4121 				u64 hint_byte_orig, struct btrfs_key *ins,
4122 				u64 flags, int delalloc)
4123 {
4124 	struct btrfs_fs_info *fs_info = root->fs_info;
4125 	int ret = 0;
4126 	int cache_block_group_error = 0;
4127 	struct btrfs_block_group *block_group = NULL;
4128 	struct find_free_extent_ctl ffe_ctl = {0};
4129 	struct btrfs_space_info *space_info;
4130 	bool full_search = false;
4131 	bool for_treelog = (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
4132 
4133 	WARN_ON(num_bytes < fs_info->sectorsize);
4134 
4135 	ffe_ctl.num_bytes = num_bytes;
4136 	ffe_ctl.empty_size = empty_size;
4137 	ffe_ctl.flags = flags;
4138 	ffe_ctl.search_start = 0;
4139 	ffe_ctl.delalloc = delalloc;
4140 	ffe_ctl.index = btrfs_bg_flags_to_raid_index(flags);
4141 	ffe_ctl.have_caching_bg = false;
4142 	ffe_ctl.orig_have_caching_bg = false;
4143 	ffe_ctl.found_offset = 0;
4144 	ffe_ctl.hint_byte = hint_byte_orig;
4145 	ffe_ctl.for_treelog = for_treelog;
4146 	ffe_ctl.policy = BTRFS_EXTENT_ALLOC_CLUSTERED;
4147 
4148 	/* For clustered allocation */
4149 	ffe_ctl.retry_clustered = false;
4150 	ffe_ctl.retry_unclustered = false;
4151 	ffe_ctl.last_ptr = NULL;
4152 	ffe_ctl.use_cluster = true;
4153 
4154 	if (btrfs_is_zoned(fs_info))
4155 		ffe_ctl.policy = BTRFS_EXTENT_ALLOC_ZONED;
4156 
4157 	ins->type = BTRFS_EXTENT_ITEM_KEY;
4158 	ins->objectid = 0;
4159 	ins->offset = 0;
4160 
4161 	trace_find_free_extent(root, num_bytes, empty_size, flags);
4162 
4163 	space_info = btrfs_find_space_info(fs_info, flags);
4164 	if (!space_info) {
4165 		btrfs_err(fs_info, "No space info for %llu", flags);
4166 		return -ENOSPC;
4167 	}
4168 
4169 	ret = prepare_allocation(fs_info, &ffe_ctl, space_info, ins);
4170 	if (ret < 0)
4171 		return ret;
4172 
4173 	ffe_ctl.search_start = max(ffe_ctl.search_start,
4174 				   first_logical_byte(fs_info, 0));
4175 	ffe_ctl.search_start = max(ffe_ctl.search_start, ffe_ctl.hint_byte);
4176 	if (ffe_ctl.search_start == ffe_ctl.hint_byte) {
4177 		block_group = btrfs_lookup_block_group(fs_info,
4178 						       ffe_ctl.search_start);
4179 		/*
4180 		 * we don't want to use the block group if it doesn't match our
4181 		 * allocation bits, or if its not cached.
4182 		 *
4183 		 * However if we are re-searching with an ideal block group
4184 		 * picked out then we don't care that the block group is cached.
4185 		 */
4186 		if (block_group && block_group_bits(block_group, flags) &&
4187 		    block_group->cached != BTRFS_CACHE_NO) {
4188 			down_read(&space_info->groups_sem);
4189 			if (list_empty(&block_group->list) ||
4190 			    block_group->ro) {
4191 				/*
4192 				 * someone is removing this block group,
4193 				 * we can't jump into the have_block_group
4194 				 * target because our list pointers are not
4195 				 * valid
4196 				 */
4197 				btrfs_put_block_group(block_group);
4198 				up_read(&space_info->groups_sem);
4199 			} else {
4200 				ffe_ctl.index = btrfs_bg_flags_to_raid_index(
4201 						block_group->flags);
4202 				btrfs_lock_block_group(block_group, delalloc);
4203 				goto have_block_group;
4204 			}
4205 		} else if (block_group) {
4206 			btrfs_put_block_group(block_group);
4207 		}
4208 	}
4209 search:
4210 	ffe_ctl.have_caching_bg = false;
4211 	if (ffe_ctl.index == btrfs_bg_flags_to_raid_index(flags) ||
4212 	    ffe_ctl.index == 0)
4213 		full_search = true;
4214 	down_read(&space_info->groups_sem);
4215 	list_for_each_entry(block_group,
4216 			    &space_info->block_groups[ffe_ctl.index], list) {
4217 		struct btrfs_block_group *bg_ret;
4218 
4219 		/* If the block group is read-only, we can skip it entirely. */
4220 		if (unlikely(block_group->ro)) {
4221 			if (for_treelog)
4222 				btrfs_clear_treelog_bg(block_group);
4223 			continue;
4224 		}
4225 
4226 		btrfs_grab_block_group(block_group, delalloc);
4227 		ffe_ctl.search_start = block_group->start;
4228 
4229 		/*
4230 		 * this can happen if we end up cycling through all the
4231 		 * raid types, but we want to make sure we only allocate
4232 		 * for the proper type.
4233 		 */
4234 		if (!block_group_bits(block_group, flags)) {
4235 			u64 extra = BTRFS_BLOCK_GROUP_DUP |
4236 				BTRFS_BLOCK_GROUP_RAID1_MASK |
4237 				BTRFS_BLOCK_GROUP_RAID56_MASK |
4238 				BTRFS_BLOCK_GROUP_RAID10;
4239 
4240 			/*
4241 			 * if they asked for extra copies and this block group
4242 			 * doesn't provide them, bail.  This does allow us to
4243 			 * fill raid0 from raid1.
4244 			 */
4245 			if ((flags & extra) && !(block_group->flags & extra))
4246 				goto loop;
4247 
4248 			/*
4249 			 * This block group has different flags than we want.
4250 			 * It's possible that we have MIXED_GROUP flag but no
4251 			 * block group is mixed.  Just skip such block group.
4252 			 */
4253 			btrfs_release_block_group(block_group, delalloc);
4254 			continue;
4255 		}
4256 
4257 have_block_group:
4258 		ffe_ctl.cached = btrfs_block_group_done(block_group);
4259 		if (unlikely(!ffe_ctl.cached)) {
4260 			ffe_ctl.have_caching_bg = true;
4261 			ret = btrfs_cache_block_group(block_group, 0);
4262 
4263 			/*
4264 			 * If we get ENOMEM here or something else we want to
4265 			 * try other block groups, because it may not be fatal.
4266 			 * However if we can't find anything else we need to
4267 			 * save our return here so that we return the actual
4268 			 * error that caused problems, not ENOSPC.
4269 			 */
4270 			if (ret < 0) {
4271 				if (!cache_block_group_error)
4272 					cache_block_group_error = ret;
4273 				ret = 0;
4274 				goto loop;
4275 			}
4276 			ret = 0;
4277 		}
4278 
4279 		if (unlikely(block_group->cached == BTRFS_CACHE_ERROR))
4280 			goto loop;
4281 
4282 		bg_ret = NULL;
4283 		ret = do_allocation(block_group, &ffe_ctl, &bg_ret);
4284 		if (ret == 0) {
4285 			if (bg_ret && bg_ret != block_group) {
4286 				btrfs_release_block_group(block_group, delalloc);
4287 				block_group = bg_ret;
4288 			}
4289 		} else if (ret == -EAGAIN) {
4290 			goto have_block_group;
4291 		} else if (ret > 0) {
4292 			goto loop;
4293 		}
4294 
4295 		/* Checks */
4296 		ffe_ctl.search_start = round_up(ffe_ctl.found_offset,
4297 					     fs_info->stripesize);
4298 
4299 		/* move on to the next group */
4300 		if (ffe_ctl.search_start + num_bytes >
4301 		    block_group->start + block_group->length) {
4302 			btrfs_add_free_space_unused(block_group,
4303 					    ffe_ctl.found_offset, num_bytes);
4304 			goto loop;
4305 		}
4306 
4307 		if (ffe_ctl.found_offset < ffe_ctl.search_start)
4308 			btrfs_add_free_space_unused(block_group,
4309 					ffe_ctl.found_offset,
4310 					ffe_ctl.search_start - ffe_ctl.found_offset);
4311 
4312 		ret = btrfs_add_reserved_bytes(block_group, ram_bytes,
4313 				num_bytes, delalloc);
4314 		if (ret == -EAGAIN) {
4315 			btrfs_add_free_space_unused(block_group,
4316 					ffe_ctl.found_offset, num_bytes);
4317 			goto loop;
4318 		}
4319 		btrfs_inc_block_group_reservations(block_group);
4320 
4321 		/* we are all good, lets return */
4322 		ins->objectid = ffe_ctl.search_start;
4323 		ins->offset = num_bytes;
4324 
4325 		trace_btrfs_reserve_extent(block_group, ffe_ctl.search_start,
4326 					   num_bytes);
4327 		btrfs_release_block_group(block_group, delalloc);
4328 		break;
4329 loop:
4330 		release_block_group(block_group, &ffe_ctl, delalloc);
4331 		cond_resched();
4332 	}
4333 	up_read(&space_info->groups_sem);
4334 
4335 	ret = find_free_extent_update_loop(fs_info, ins, &ffe_ctl, full_search);
4336 	if (ret > 0)
4337 		goto search;
4338 
4339 	if (ret == -ENOSPC && !cache_block_group_error) {
4340 		/*
4341 		 * Use ffe_ctl->total_free_space as fallback if we can't find
4342 		 * any contiguous hole.
4343 		 */
4344 		if (!ffe_ctl.max_extent_size)
4345 			ffe_ctl.max_extent_size = ffe_ctl.total_free_space;
4346 		spin_lock(&space_info->lock);
4347 		space_info->max_extent_size = ffe_ctl.max_extent_size;
4348 		spin_unlock(&space_info->lock);
4349 		ins->offset = ffe_ctl.max_extent_size;
4350 	} else if (ret == -ENOSPC) {
4351 		ret = cache_block_group_error;
4352 	}
4353 	return ret;
4354 }
4355 
4356 /*
4357  * btrfs_reserve_extent - entry point to the extent allocator. Tries to find a
4358  *			  hole that is at least as big as @num_bytes.
4359  *
4360  * @root           -	The root that will contain this extent
4361  *
4362  * @ram_bytes      -	The amount of space in ram that @num_bytes take. This
4363  *			is used for accounting purposes. This value differs
4364  *			from @num_bytes only in the case of compressed extents.
4365  *
4366  * @num_bytes      -	Number of bytes to allocate on-disk.
4367  *
4368  * @min_alloc_size -	Indicates the minimum amount of space that the
4369  *			allocator should try to satisfy. In some cases
4370  *			@num_bytes may be larger than what is required and if
4371  *			the filesystem is fragmented then allocation fails.
4372  *			However, the presence of @min_alloc_size gives a
4373  *			chance to try and satisfy the smaller allocation.
4374  *
4375  * @empty_size     -	A hint that you plan on doing more COW. This is the
4376  *			size in bytes the allocator should try to find free
4377  *			next to the block it returns.  This is just a hint and
4378  *			may be ignored by the allocator.
4379  *
4380  * @hint_byte      -	Hint to the allocator to start searching above the byte
4381  *			address passed. It might be ignored.
4382  *
4383  * @ins            -	This key is modified to record the found hole. It will
4384  *			have the following values:
4385  *			ins->objectid == start position
4386  *			ins->flags = BTRFS_EXTENT_ITEM_KEY
4387  *			ins->offset == the size of the hole.
4388  *
4389  * @is_data        -	Boolean flag indicating whether an extent is
4390  *			allocated for data (true) or metadata (false)
4391  *
4392  * @delalloc       -	Boolean flag indicating whether this allocation is for
4393  *			delalloc or not. If 'true' data_rwsem of block groups
4394  *			is going to be acquired.
4395  *
4396  *
4397  * Returns 0 when an allocation succeeded or < 0 when an error occurred. In
4398  * case -ENOSPC is returned then @ins->offset will contain the size of the
4399  * largest available hole the allocator managed to find.
4400  */
4401 int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes,
4402 			 u64 num_bytes, u64 min_alloc_size,
4403 			 u64 empty_size, u64 hint_byte,
4404 			 struct btrfs_key *ins, int is_data, int delalloc)
4405 {
4406 	struct btrfs_fs_info *fs_info = root->fs_info;
4407 	bool final_tried = num_bytes == min_alloc_size;
4408 	u64 flags;
4409 	int ret;
4410 	bool for_treelog = (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
4411 
4412 	flags = get_alloc_profile_by_root(root, is_data);
4413 again:
4414 	WARN_ON(num_bytes < fs_info->sectorsize);
4415 	ret = find_free_extent(root, ram_bytes, num_bytes, empty_size,
4416 			       hint_byte, ins, flags, delalloc);
4417 	if (!ret && !is_data) {
4418 		btrfs_dec_block_group_reservations(fs_info, ins->objectid);
4419 	} else if (ret == -ENOSPC) {
4420 		if (!final_tried && ins->offset) {
4421 			num_bytes = min(num_bytes >> 1, ins->offset);
4422 			num_bytes = round_down(num_bytes,
4423 					       fs_info->sectorsize);
4424 			num_bytes = max(num_bytes, min_alloc_size);
4425 			ram_bytes = num_bytes;
4426 			if (num_bytes == min_alloc_size)
4427 				final_tried = true;
4428 			goto again;
4429 		} else if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
4430 			struct btrfs_space_info *sinfo;
4431 
4432 			sinfo = btrfs_find_space_info(fs_info, flags);
4433 			btrfs_err(fs_info,
4434 			"allocation failed flags %llu, wanted %llu tree-log %d",
4435 				  flags, num_bytes, for_treelog);
4436 			if (sinfo)
4437 				btrfs_dump_space_info(fs_info, sinfo,
4438 						      num_bytes, 1);
4439 		}
4440 	}
4441 
4442 	return ret;
4443 }
4444 
4445 int btrfs_free_reserved_extent(struct btrfs_fs_info *fs_info,
4446 			       u64 start, u64 len, int delalloc)
4447 {
4448 	struct btrfs_block_group *cache;
4449 
4450 	cache = btrfs_lookup_block_group(fs_info, start);
4451 	if (!cache) {
4452 		btrfs_err(fs_info, "Unable to find block group for %llu",
4453 			  start);
4454 		return -ENOSPC;
4455 	}
4456 
4457 	btrfs_add_free_space(cache, start, len);
4458 	btrfs_free_reserved_bytes(cache, len, delalloc);
4459 	trace_btrfs_reserved_extent_free(fs_info, start, len);
4460 
4461 	btrfs_put_block_group(cache);
4462 	return 0;
4463 }
4464 
4465 int btrfs_pin_reserved_extent(struct btrfs_trans_handle *trans, u64 start,
4466 			      u64 len)
4467 {
4468 	struct btrfs_block_group *cache;
4469 	int ret = 0;
4470 
4471 	cache = btrfs_lookup_block_group(trans->fs_info, start);
4472 	if (!cache) {
4473 		btrfs_err(trans->fs_info, "unable to find block group for %llu",
4474 			  start);
4475 		return -ENOSPC;
4476 	}
4477 
4478 	ret = pin_down_extent(trans, cache, start, len, 1);
4479 	btrfs_put_block_group(cache);
4480 	return ret;
4481 }
4482 
4483 static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
4484 				      u64 parent, u64 root_objectid,
4485 				      u64 flags, u64 owner, u64 offset,
4486 				      struct btrfs_key *ins, int ref_mod)
4487 {
4488 	struct btrfs_fs_info *fs_info = trans->fs_info;
4489 	int ret;
4490 	struct btrfs_extent_item *extent_item;
4491 	struct btrfs_extent_inline_ref *iref;
4492 	struct btrfs_path *path;
4493 	struct extent_buffer *leaf;
4494 	int type;
4495 	u32 size;
4496 
4497 	if (parent > 0)
4498 		type = BTRFS_SHARED_DATA_REF_KEY;
4499 	else
4500 		type = BTRFS_EXTENT_DATA_REF_KEY;
4501 
4502 	size = sizeof(*extent_item) + btrfs_extent_inline_ref_size(type);
4503 
4504 	path = btrfs_alloc_path();
4505 	if (!path)
4506 		return -ENOMEM;
4507 
4508 	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
4509 				      ins, size);
4510 	if (ret) {
4511 		btrfs_free_path(path);
4512 		return ret;
4513 	}
4514 
4515 	leaf = path->nodes[0];
4516 	extent_item = btrfs_item_ptr(leaf, path->slots[0],
4517 				     struct btrfs_extent_item);
4518 	btrfs_set_extent_refs(leaf, extent_item, ref_mod);
4519 	btrfs_set_extent_generation(leaf, extent_item, trans->transid);
4520 	btrfs_set_extent_flags(leaf, extent_item,
4521 			       flags | BTRFS_EXTENT_FLAG_DATA);
4522 
4523 	iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
4524 	btrfs_set_extent_inline_ref_type(leaf, iref, type);
4525 	if (parent > 0) {
4526 		struct btrfs_shared_data_ref *ref;
4527 		ref = (struct btrfs_shared_data_ref *)(iref + 1);
4528 		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
4529 		btrfs_set_shared_data_ref_count(leaf, ref, ref_mod);
4530 	} else {
4531 		struct btrfs_extent_data_ref *ref;
4532 		ref = (struct btrfs_extent_data_ref *)(&iref->offset);
4533 		btrfs_set_extent_data_ref_root(leaf, ref, root_objectid);
4534 		btrfs_set_extent_data_ref_objectid(leaf, ref, owner);
4535 		btrfs_set_extent_data_ref_offset(leaf, ref, offset);
4536 		btrfs_set_extent_data_ref_count(leaf, ref, ref_mod);
4537 	}
4538 
4539 	btrfs_mark_buffer_dirty(path->nodes[0]);
4540 	btrfs_free_path(path);
4541 
4542 	ret = remove_from_free_space_tree(trans, ins->objectid, ins->offset);
4543 	if (ret)
4544 		return ret;
4545 
4546 	ret = btrfs_update_block_group(trans, ins->objectid, ins->offset, 1);
4547 	if (ret) { /* -ENOENT, logic error */
4548 		btrfs_err(fs_info, "update block group failed for %llu %llu",
4549 			ins->objectid, ins->offset);
4550 		BUG();
4551 	}
4552 	trace_btrfs_reserved_extent_alloc(fs_info, ins->objectid, ins->offset);
4553 	return ret;
4554 }
4555 
4556 static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
4557 				     struct btrfs_delayed_ref_node *node,
4558 				     struct btrfs_delayed_extent_op *extent_op)
4559 {
4560 	struct btrfs_fs_info *fs_info = trans->fs_info;
4561 	int ret;
4562 	struct btrfs_extent_item *extent_item;
4563 	struct btrfs_key extent_key;
4564 	struct btrfs_tree_block_info *block_info;
4565 	struct btrfs_extent_inline_ref *iref;
4566 	struct btrfs_path *path;
4567 	struct extent_buffer *leaf;
4568 	struct btrfs_delayed_tree_ref *ref;
4569 	u32 size = sizeof(*extent_item) + sizeof(*iref);
4570 	u64 num_bytes;
4571 	u64 flags = extent_op->flags_to_set;
4572 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
4573 
4574 	ref = btrfs_delayed_node_to_tree_ref(node);
4575 
4576 	extent_key.objectid = node->bytenr;
4577 	if (skinny_metadata) {
4578 		extent_key.offset = ref->level;
4579 		extent_key.type = BTRFS_METADATA_ITEM_KEY;
4580 		num_bytes = fs_info->nodesize;
4581 	} else {
4582 		extent_key.offset = node->num_bytes;
4583 		extent_key.type = BTRFS_EXTENT_ITEM_KEY;
4584 		size += sizeof(*block_info);
4585 		num_bytes = node->num_bytes;
4586 	}
4587 
4588 	path = btrfs_alloc_path();
4589 	if (!path)
4590 		return -ENOMEM;
4591 
4592 	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
4593 				      &extent_key, size);
4594 	if (ret) {
4595 		btrfs_free_path(path);
4596 		return ret;
4597 	}
4598 
4599 	leaf = path->nodes[0];
4600 	extent_item = btrfs_item_ptr(leaf, path->slots[0],
4601 				     struct btrfs_extent_item);
4602 	btrfs_set_extent_refs(leaf, extent_item, 1);
4603 	btrfs_set_extent_generation(leaf, extent_item, trans->transid);
4604 	btrfs_set_extent_flags(leaf, extent_item,
4605 			       flags | BTRFS_EXTENT_FLAG_TREE_BLOCK);
4606 
4607 	if (skinny_metadata) {
4608 		iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
4609 	} else {
4610 		block_info = (struct btrfs_tree_block_info *)(extent_item + 1);
4611 		btrfs_set_tree_block_key(leaf, block_info, &extent_op->key);
4612 		btrfs_set_tree_block_level(leaf, block_info, ref->level);
4613 		iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
4614 	}
4615 
4616 	if (node->type == BTRFS_SHARED_BLOCK_REF_KEY) {
4617 		btrfs_set_extent_inline_ref_type(leaf, iref,
4618 						 BTRFS_SHARED_BLOCK_REF_KEY);
4619 		btrfs_set_extent_inline_ref_offset(leaf, iref, ref->parent);
4620 	} else {
4621 		btrfs_set_extent_inline_ref_type(leaf, iref,
4622 						 BTRFS_TREE_BLOCK_REF_KEY);
4623 		btrfs_set_extent_inline_ref_offset(leaf, iref, ref->root);
4624 	}
4625 
4626 	btrfs_mark_buffer_dirty(leaf);
4627 	btrfs_free_path(path);
4628 
4629 	ret = remove_from_free_space_tree(trans, extent_key.objectid,
4630 					  num_bytes);
4631 	if (ret)
4632 		return ret;
4633 
4634 	ret = btrfs_update_block_group(trans, extent_key.objectid,
4635 				       fs_info->nodesize, 1);
4636 	if (ret) { /* -ENOENT, logic error */
4637 		btrfs_err(fs_info, "update block group failed for %llu %llu",
4638 			extent_key.objectid, extent_key.offset);
4639 		BUG();
4640 	}
4641 
4642 	trace_btrfs_reserved_extent_alloc(fs_info, extent_key.objectid,
4643 					  fs_info->nodesize);
4644 	return ret;
4645 }
4646 
4647 int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
4648 				     struct btrfs_root *root, u64 owner,
4649 				     u64 offset, u64 ram_bytes,
4650 				     struct btrfs_key *ins)
4651 {
4652 	struct btrfs_ref generic_ref = { 0 };
4653 
4654 	BUG_ON(root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
4655 
4656 	btrfs_init_generic_ref(&generic_ref, BTRFS_ADD_DELAYED_EXTENT,
4657 			       ins->objectid, ins->offset, 0);
4658 	btrfs_init_data_ref(&generic_ref, root->root_key.objectid, owner, offset);
4659 	btrfs_ref_tree_mod(root->fs_info, &generic_ref);
4660 
4661 	return btrfs_add_delayed_data_ref(trans, &generic_ref, ram_bytes);
4662 }
4663 
4664 /*
4665  * this is used by the tree logging recovery code.  It records that
4666  * an extent has been allocated and makes sure to clear the free
4667  * space cache bits as well
4668  */
4669 int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
4670 				   u64 root_objectid, u64 owner, u64 offset,
4671 				   struct btrfs_key *ins)
4672 {
4673 	struct btrfs_fs_info *fs_info = trans->fs_info;
4674 	int ret;
4675 	struct btrfs_block_group *block_group;
4676 	struct btrfs_space_info *space_info;
4677 
4678 	/*
4679 	 * Mixed block groups will exclude before processing the log so we only
4680 	 * need to do the exclude dance if this fs isn't mixed.
4681 	 */
4682 	if (!btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
4683 		ret = __exclude_logged_extent(fs_info, ins->objectid,
4684 					      ins->offset);
4685 		if (ret)
4686 			return ret;
4687 	}
4688 
4689 	block_group = btrfs_lookup_block_group(fs_info, ins->objectid);
4690 	if (!block_group)
4691 		return -EINVAL;
4692 
4693 	space_info = block_group->space_info;
4694 	spin_lock(&space_info->lock);
4695 	spin_lock(&block_group->lock);
4696 	space_info->bytes_reserved += ins->offset;
4697 	block_group->reserved += ins->offset;
4698 	spin_unlock(&block_group->lock);
4699 	spin_unlock(&space_info->lock);
4700 
4701 	ret = alloc_reserved_file_extent(trans, 0, root_objectid, 0, owner,
4702 					 offset, ins, 1);
4703 	if (ret)
4704 		btrfs_pin_extent(trans, ins->objectid, ins->offset, 1);
4705 	btrfs_put_block_group(block_group);
4706 	return ret;
4707 }
4708 
4709 static struct extent_buffer *
4710 btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4711 		      u64 bytenr, int level, u64 owner,
4712 		      enum btrfs_lock_nesting nest)
4713 {
4714 	struct btrfs_fs_info *fs_info = root->fs_info;
4715 	struct extent_buffer *buf;
4716 
4717 	buf = btrfs_find_create_tree_block(fs_info, bytenr, owner, level);
4718 	if (IS_ERR(buf))
4719 		return buf;
4720 
4721 	/*
4722 	 * Extra safety check in case the extent tree is corrupted and extent
4723 	 * allocator chooses to use a tree block which is already used and
4724 	 * locked.
4725 	 */
4726 	if (buf->lock_owner == current->pid) {
4727 		btrfs_err_rl(fs_info,
4728 "tree block %llu owner %llu already locked by pid=%d, extent tree corruption detected",
4729 			buf->start, btrfs_header_owner(buf), current->pid);
4730 		free_extent_buffer(buf);
4731 		return ERR_PTR(-EUCLEAN);
4732 	}
4733 
4734 	/*
4735 	 * This needs to stay, because we could allocate a freed block from an
4736 	 * old tree into a new tree, so we need to make sure this new block is
4737 	 * set to the appropriate level and owner.
4738 	 */
4739 	btrfs_set_buffer_lockdep_class(owner, buf, level);
4740 	__btrfs_tree_lock(buf, nest);
4741 	btrfs_clean_tree_block(buf);
4742 	clear_bit(EXTENT_BUFFER_STALE, &buf->bflags);
4743 	clear_bit(EXTENT_BUFFER_NO_CHECK, &buf->bflags);
4744 
4745 	set_extent_buffer_uptodate(buf);
4746 
4747 	memzero_extent_buffer(buf, 0, sizeof(struct btrfs_header));
4748 	btrfs_set_header_level(buf, level);
4749 	btrfs_set_header_bytenr(buf, buf->start);
4750 	btrfs_set_header_generation(buf, trans->transid);
4751 	btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV);
4752 	btrfs_set_header_owner(buf, owner);
4753 	write_extent_buffer_fsid(buf, fs_info->fs_devices->metadata_uuid);
4754 	write_extent_buffer_chunk_tree_uuid(buf, fs_info->chunk_tree_uuid);
4755 	if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
4756 		buf->log_index = root->log_transid % 2;
4757 		/*
4758 		 * we allow two log transactions at a time, use different
4759 		 * EXTENT bit to differentiate dirty pages.
4760 		 */
4761 		if (buf->log_index == 0)
4762 			set_extent_dirty(&root->dirty_log_pages, buf->start,
4763 					buf->start + buf->len - 1, GFP_NOFS);
4764 		else
4765 			set_extent_new(&root->dirty_log_pages, buf->start,
4766 					buf->start + buf->len - 1);
4767 	} else {
4768 		buf->log_index = -1;
4769 		set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
4770 			 buf->start + buf->len - 1, GFP_NOFS);
4771 	}
4772 	/* this returns a buffer locked for blocking */
4773 	return buf;
4774 }
4775 
4776 /*
4777  * finds a free extent and does all the dirty work required for allocation
4778  * returns the tree buffer or an ERR_PTR on error.
4779  */
4780 struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
4781 					     struct btrfs_root *root,
4782 					     u64 parent, u64 root_objectid,
4783 					     const struct btrfs_disk_key *key,
4784 					     int level, u64 hint,
4785 					     u64 empty_size,
4786 					     enum btrfs_lock_nesting nest)
4787 {
4788 	struct btrfs_fs_info *fs_info = root->fs_info;
4789 	struct btrfs_key ins;
4790 	struct btrfs_block_rsv *block_rsv;
4791 	struct extent_buffer *buf;
4792 	struct btrfs_delayed_extent_op *extent_op;
4793 	struct btrfs_ref generic_ref = { 0 };
4794 	u64 flags = 0;
4795 	int ret;
4796 	u32 blocksize = fs_info->nodesize;
4797 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
4798 
4799 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
4800 	if (btrfs_is_testing(fs_info)) {
4801 		buf = btrfs_init_new_buffer(trans, root, root->alloc_bytenr,
4802 					    level, root_objectid, nest);
4803 		if (!IS_ERR(buf))
4804 			root->alloc_bytenr += blocksize;
4805 		return buf;
4806 	}
4807 #endif
4808 
4809 	block_rsv = btrfs_use_block_rsv(trans, root, blocksize);
4810 	if (IS_ERR(block_rsv))
4811 		return ERR_CAST(block_rsv);
4812 
4813 	ret = btrfs_reserve_extent(root, blocksize, blocksize, blocksize,
4814 				   empty_size, hint, &ins, 0, 0);
4815 	if (ret)
4816 		goto out_unuse;
4817 
4818 	buf = btrfs_init_new_buffer(trans, root, ins.objectid, level,
4819 				    root_objectid, nest);
4820 	if (IS_ERR(buf)) {
4821 		ret = PTR_ERR(buf);
4822 		goto out_free_reserved;
4823 	}
4824 
4825 	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
4826 		if (parent == 0)
4827 			parent = ins.objectid;
4828 		flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
4829 	} else
4830 		BUG_ON(parent > 0);
4831 
4832 	if (root_objectid != BTRFS_TREE_LOG_OBJECTID) {
4833 		extent_op = btrfs_alloc_delayed_extent_op();
4834 		if (!extent_op) {
4835 			ret = -ENOMEM;
4836 			goto out_free_buf;
4837 		}
4838 		if (key)
4839 			memcpy(&extent_op->key, key, sizeof(extent_op->key));
4840 		else
4841 			memset(&extent_op->key, 0, sizeof(extent_op->key));
4842 		extent_op->flags_to_set = flags;
4843 		extent_op->update_key = skinny_metadata ? false : true;
4844 		extent_op->update_flags = true;
4845 		extent_op->is_data = false;
4846 		extent_op->level = level;
4847 
4848 		btrfs_init_generic_ref(&generic_ref, BTRFS_ADD_DELAYED_EXTENT,
4849 				       ins.objectid, ins.offset, parent);
4850 		generic_ref.real_root = root->root_key.objectid;
4851 		btrfs_init_tree_ref(&generic_ref, level, root_objectid);
4852 		btrfs_ref_tree_mod(fs_info, &generic_ref);
4853 		ret = btrfs_add_delayed_tree_ref(trans, &generic_ref, extent_op);
4854 		if (ret)
4855 			goto out_free_delayed;
4856 	}
4857 	return buf;
4858 
4859 out_free_delayed:
4860 	btrfs_free_delayed_extent_op(extent_op);
4861 out_free_buf:
4862 	free_extent_buffer(buf);
4863 out_free_reserved:
4864 	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 0);
4865 out_unuse:
4866 	btrfs_unuse_block_rsv(fs_info, block_rsv, blocksize);
4867 	return ERR_PTR(ret);
4868 }
4869 
4870 struct walk_control {
4871 	u64 refs[BTRFS_MAX_LEVEL];
4872 	u64 flags[BTRFS_MAX_LEVEL];
4873 	struct btrfs_key update_progress;
4874 	struct btrfs_key drop_progress;
4875 	int drop_level;
4876 	int stage;
4877 	int level;
4878 	int shared_level;
4879 	int update_ref;
4880 	int keep_locks;
4881 	int reada_slot;
4882 	int reada_count;
4883 	int restarted;
4884 };
4885 
4886 #define DROP_REFERENCE	1
4887 #define UPDATE_BACKREF	2
4888 
4889 static noinline void reada_walk_down(struct btrfs_trans_handle *trans,
4890 				     struct btrfs_root *root,
4891 				     struct walk_control *wc,
4892 				     struct btrfs_path *path)
4893 {
4894 	struct btrfs_fs_info *fs_info = root->fs_info;
4895 	u64 bytenr;
4896 	u64 generation;
4897 	u64 refs;
4898 	u64 flags;
4899 	u32 nritems;
4900 	struct btrfs_key key;
4901 	struct extent_buffer *eb;
4902 	int ret;
4903 	int slot;
4904 	int nread = 0;
4905 
4906 	if (path->slots[wc->level] < wc->reada_slot) {
4907 		wc->reada_count = wc->reada_count * 2 / 3;
4908 		wc->reada_count = max(wc->reada_count, 2);
4909 	} else {
4910 		wc->reada_count = wc->reada_count * 3 / 2;
4911 		wc->reada_count = min_t(int, wc->reada_count,
4912 					BTRFS_NODEPTRS_PER_BLOCK(fs_info));
4913 	}
4914 
4915 	eb = path->nodes[wc->level];
4916 	nritems = btrfs_header_nritems(eb);
4917 
4918 	for (slot = path->slots[wc->level]; slot < nritems; slot++) {
4919 		if (nread >= wc->reada_count)
4920 			break;
4921 
4922 		cond_resched();
4923 		bytenr = btrfs_node_blockptr(eb, slot);
4924 		generation = btrfs_node_ptr_generation(eb, slot);
4925 
4926 		if (slot == path->slots[wc->level])
4927 			goto reada;
4928 
4929 		if (wc->stage == UPDATE_BACKREF &&
4930 		    generation <= root->root_key.offset)
4931 			continue;
4932 
4933 		/* We don't lock the tree block, it's OK to be racy here */
4934 		ret = btrfs_lookup_extent_info(trans, fs_info, bytenr,
4935 					       wc->level - 1, 1, &refs,
4936 					       &flags);
4937 		/* We don't care about errors in readahead. */
4938 		if (ret < 0)
4939 			continue;
4940 		BUG_ON(refs == 0);
4941 
4942 		if (wc->stage == DROP_REFERENCE) {
4943 			if (refs == 1)
4944 				goto reada;
4945 
4946 			if (wc->level == 1 &&
4947 			    (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
4948 				continue;
4949 			if (!wc->update_ref ||
4950 			    generation <= root->root_key.offset)
4951 				continue;
4952 			btrfs_node_key_to_cpu(eb, &key, slot);
4953 			ret = btrfs_comp_cpu_keys(&key,
4954 						  &wc->update_progress);
4955 			if (ret < 0)
4956 				continue;
4957 		} else {
4958 			if (wc->level == 1 &&
4959 			    (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
4960 				continue;
4961 		}
4962 reada:
4963 		btrfs_readahead_node_child(eb, slot);
4964 		nread++;
4965 	}
4966 	wc->reada_slot = slot;
4967 }
4968 
4969 /*
4970  * helper to process tree block while walking down the tree.
4971  *
4972  * when wc->stage == UPDATE_BACKREF, this function updates
4973  * back refs for pointers in the block.
4974  *
4975  * NOTE: return value 1 means we should stop walking down.
4976  */
4977 static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
4978 				   struct btrfs_root *root,
4979 				   struct btrfs_path *path,
4980 				   struct walk_control *wc, int lookup_info)
4981 {
4982 	struct btrfs_fs_info *fs_info = root->fs_info;
4983 	int level = wc->level;
4984 	struct extent_buffer *eb = path->nodes[level];
4985 	u64 flag = BTRFS_BLOCK_FLAG_FULL_BACKREF;
4986 	int ret;
4987 
4988 	if (wc->stage == UPDATE_BACKREF &&
4989 	    btrfs_header_owner(eb) != root->root_key.objectid)
4990 		return 1;
4991 
4992 	/*
4993 	 * when reference count of tree block is 1, it won't increase
4994 	 * again. once full backref flag is set, we never clear it.
4995 	 */
4996 	if (lookup_info &&
4997 	    ((wc->stage == DROP_REFERENCE && wc->refs[level] != 1) ||
4998 	     (wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag)))) {
4999 		BUG_ON(!path->locks[level]);
5000 		ret = btrfs_lookup_extent_info(trans, fs_info,
5001 					       eb->start, level, 1,
5002 					       &wc->refs[level],
5003 					       &wc->flags[level]);
5004 		BUG_ON(ret == -ENOMEM);
5005 		if (ret)
5006 			return ret;
5007 		BUG_ON(wc->refs[level] == 0);
5008 	}
5009 
5010 	if (wc->stage == DROP_REFERENCE) {
5011 		if (wc->refs[level] > 1)
5012 			return 1;
5013 
5014 		if (path->locks[level] && !wc->keep_locks) {
5015 			btrfs_tree_unlock_rw(eb, path->locks[level]);
5016 			path->locks[level] = 0;
5017 		}
5018 		return 0;
5019 	}
5020 
5021 	/* wc->stage == UPDATE_BACKREF */
5022 	if (!(wc->flags[level] & flag)) {
5023 		BUG_ON(!path->locks[level]);
5024 		ret = btrfs_inc_ref(trans, root, eb, 1);
5025 		BUG_ON(ret); /* -ENOMEM */
5026 		ret = btrfs_dec_ref(trans, root, eb, 0);
5027 		BUG_ON(ret); /* -ENOMEM */
5028 		ret = btrfs_set_disk_extent_flags(trans, eb, flag,
5029 						  btrfs_header_level(eb), 0);
5030 		BUG_ON(ret); /* -ENOMEM */
5031 		wc->flags[level] |= flag;
5032 	}
5033 
5034 	/*
5035 	 * the block is shared by multiple trees, so it's not good to
5036 	 * keep the tree lock
5037 	 */
5038 	if (path->locks[level] && level > 0) {
5039 		btrfs_tree_unlock_rw(eb, path->locks[level]);
5040 		path->locks[level] = 0;
5041 	}
5042 	return 0;
5043 }
5044 
5045 /*
5046  * This is used to verify a ref exists for this root to deal with a bug where we
5047  * would have a drop_progress key that hadn't been updated properly.
5048  */
5049 static int check_ref_exists(struct btrfs_trans_handle *trans,
5050 			    struct btrfs_root *root, u64 bytenr, u64 parent,
5051 			    int level)
5052 {
5053 	struct btrfs_path *path;
5054 	struct btrfs_extent_inline_ref *iref;
5055 	int ret;
5056 
5057 	path = btrfs_alloc_path();
5058 	if (!path)
5059 		return -ENOMEM;
5060 
5061 	ret = lookup_extent_backref(trans, path, &iref, bytenr,
5062 				    root->fs_info->nodesize, parent,
5063 				    root->root_key.objectid, level, 0);
5064 	btrfs_free_path(path);
5065 	if (ret == -ENOENT)
5066 		return 0;
5067 	if (ret < 0)
5068 		return ret;
5069 	return 1;
5070 }
5071 
5072 /*
5073  * helper to process tree block pointer.
5074  *
5075  * when wc->stage == DROP_REFERENCE, this function checks
5076  * reference count of the block pointed to. if the block
5077  * is shared and we need update back refs for the subtree
5078  * rooted at the block, this function changes wc->stage to
5079  * UPDATE_BACKREF. if the block is shared and there is no
5080  * need to update back, this function drops the reference
5081  * to the block.
5082  *
5083  * NOTE: return value 1 means we should stop walking down.
5084  */
5085 static noinline int do_walk_down(struct btrfs_trans_handle *trans,
5086 				 struct btrfs_root *root,
5087 				 struct btrfs_path *path,
5088 				 struct walk_control *wc, int *lookup_info)
5089 {
5090 	struct btrfs_fs_info *fs_info = root->fs_info;
5091 	u64 bytenr;
5092 	u64 generation;
5093 	u64 parent;
5094 	struct btrfs_key key;
5095 	struct btrfs_key first_key;
5096 	struct btrfs_ref ref = { 0 };
5097 	struct extent_buffer *next;
5098 	int level = wc->level;
5099 	int reada = 0;
5100 	int ret = 0;
5101 	bool need_account = false;
5102 
5103 	generation = btrfs_node_ptr_generation(path->nodes[level],
5104 					       path->slots[level]);
5105 	/*
5106 	 * if the lower level block was created before the snapshot
5107 	 * was created, we know there is no need to update back refs
5108 	 * for the subtree
5109 	 */
5110 	if (wc->stage == UPDATE_BACKREF &&
5111 	    generation <= root->root_key.offset) {
5112 		*lookup_info = 1;
5113 		return 1;
5114 	}
5115 
5116 	bytenr = btrfs_node_blockptr(path->nodes[level], path->slots[level]);
5117 	btrfs_node_key_to_cpu(path->nodes[level], &first_key,
5118 			      path->slots[level]);
5119 
5120 	next = find_extent_buffer(fs_info, bytenr);
5121 	if (!next) {
5122 		next = btrfs_find_create_tree_block(fs_info, bytenr,
5123 				root->root_key.objectid, level - 1);
5124 		if (IS_ERR(next))
5125 			return PTR_ERR(next);
5126 		reada = 1;
5127 	}
5128 	btrfs_tree_lock(next);
5129 
5130 	ret = btrfs_lookup_extent_info(trans, fs_info, bytenr, level - 1, 1,
5131 				       &wc->refs[level - 1],
5132 				       &wc->flags[level - 1]);
5133 	if (ret < 0)
5134 		goto out_unlock;
5135 
5136 	if (unlikely(wc->refs[level - 1] == 0)) {
5137 		btrfs_err(fs_info, "Missing references.");
5138 		ret = -EIO;
5139 		goto out_unlock;
5140 	}
5141 	*lookup_info = 0;
5142 
5143 	if (wc->stage == DROP_REFERENCE) {
5144 		if (wc->refs[level - 1] > 1) {
5145 			need_account = true;
5146 			if (level == 1 &&
5147 			    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))
5148 				goto skip;
5149 
5150 			if (!wc->update_ref ||
5151 			    generation <= root->root_key.offset)
5152 				goto skip;
5153 
5154 			btrfs_node_key_to_cpu(path->nodes[level], &key,
5155 					      path->slots[level]);
5156 			ret = btrfs_comp_cpu_keys(&key, &wc->update_progress);
5157 			if (ret < 0)
5158 				goto skip;
5159 
5160 			wc->stage = UPDATE_BACKREF;
5161 			wc->shared_level = level - 1;
5162 		}
5163 	} else {
5164 		if (level == 1 &&
5165 		    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))
5166 			goto skip;
5167 	}
5168 
5169 	if (!btrfs_buffer_uptodate(next, generation, 0)) {
5170 		btrfs_tree_unlock(next);
5171 		free_extent_buffer(next);
5172 		next = NULL;
5173 		*lookup_info = 1;
5174 	}
5175 
5176 	if (!next) {
5177 		if (reada && level == 1)
5178 			reada_walk_down(trans, root, wc, path);
5179 		next = read_tree_block(fs_info, bytenr, root->root_key.objectid,
5180 				       generation, level - 1, &first_key);
5181 		if (IS_ERR(next)) {
5182 			return PTR_ERR(next);
5183 		} else if (!extent_buffer_uptodate(next)) {
5184 			free_extent_buffer(next);
5185 			return -EIO;
5186 		}
5187 		btrfs_tree_lock(next);
5188 	}
5189 
5190 	level--;
5191 	ASSERT(level == btrfs_header_level(next));
5192 	if (level != btrfs_header_level(next)) {
5193 		btrfs_err(root->fs_info, "mismatched level");
5194 		ret = -EIO;
5195 		goto out_unlock;
5196 	}
5197 	path->nodes[level] = next;
5198 	path->slots[level] = 0;
5199 	path->locks[level] = BTRFS_WRITE_LOCK;
5200 	wc->level = level;
5201 	if (wc->level == 1)
5202 		wc->reada_slot = 0;
5203 	return 0;
5204 skip:
5205 	wc->refs[level - 1] = 0;
5206 	wc->flags[level - 1] = 0;
5207 	if (wc->stage == DROP_REFERENCE) {
5208 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
5209 			parent = path->nodes[level]->start;
5210 		} else {
5211 			ASSERT(root->root_key.objectid ==
5212 			       btrfs_header_owner(path->nodes[level]));
5213 			if (root->root_key.objectid !=
5214 			    btrfs_header_owner(path->nodes[level])) {
5215 				btrfs_err(root->fs_info,
5216 						"mismatched block owner");
5217 				ret = -EIO;
5218 				goto out_unlock;
5219 			}
5220 			parent = 0;
5221 		}
5222 
5223 		/*
5224 		 * If we had a drop_progress we need to verify the refs are set
5225 		 * as expected.  If we find our ref then we know that from here
5226 		 * on out everything should be correct, and we can clear the
5227 		 * ->restarted flag.
5228 		 */
5229 		if (wc->restarted) {
5230 			ret = check_ref_exists(trans, root, bytenr, parent,
5231 					       level - 1);
5232 			if (ret < 0)
5233 				goto out_unlock;
5234 			if (ret == 0)
5235 				goto no_delete;
5236 			ret = 0;
5237 			wc->restarted = 0;
5238 		}
5239 
5240 		/*
5241 		 * Reloc tree doesn't contribute to qgroup numbers, and we have
5242 		 * already accounted them at merge time (replace_path),
5243 		 * thus we could skip expensive subtree trace here.
5244 		 */
5245 		if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
5246 		    need_account) {
5247 			ret = btrfs_qgroup_trace_subtree(trans, next,
5248 							 generation, level - 1);
5249 			if (ret) {
5250 				btrfs_err_rl(fs_info,
5251 					     "Error %d accounting shared subtree. Quota is out of sync, rescan required.",
5252 					     ret);
5253 			}
5254 		}
5255 
5256 		/*
5257 		 * We need to update the next key in our walk control so we can
5258 		 * update the drop_progress key accordingly.  We don't care if
5259 		 * find_next_key doesn't find a key because that means we're at
5260 		 * the end and are going to clean up now.
5261 		 */
5262 		wc->drop_level = level;
5263 		find_next_key(path, level, &wc->drop_progress);
5264 
5265 		btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, bytenr,
5266 				       fs_info->nodesize, parent);
5267 		btrfs_init_tree_ref(&ref, level - 1, root->root_key.objectid);
5268 		ret = btrfs_free_extent(trans, &ref);
5269 		if (ret)
5270 			goto out_unlock;
5271 	}
5272 no_delete:
5273 	*lookup_info = 1;
5274 	ret = 1;
5275 
5276 out_unlock:
5277 	btrfs_tree_unlock(next);
5278 	free_extent_buffer(next);
5279 
5280 	return ret;
5281 }
5282 
5283 /*
5284  * helper to process tree block while walking up the tree.
5285  *
5286  * when wc->stage == DROP_REFERENCE, this function drops
5287  * reference count on the block.
5288  *
5289  * when wc->stage == UPDATE_BACKREF, this function changes
5290  * wc->stage back to DROP_REFERENCE if we changed wc->stage
5291  * to UPDATE_BACKREF previously while processing the block.
5292  *
5293  * NOTE: return value 1 means we should stop walking up.
5294  */
5295 static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
5296 				 struct btrfs_root *root,
5297 				 struct btrfs_path *path,
5298 				 struct walk_control *wc)
5299 {
5300 	struct btrfs_fs_info *fs_info = root->fs_info;
5301 	int ret;
5302 	int level = wc->level;
5303 	struct extent_buffer *eb = path->nodes[level];
5304 	u64 parent = 0;
5305 
5306 	if (wc->stage == UPDATE_BACKREF) {
5307 		BUG_ON(wc->shared_level < level);
5308 		if (level < wc->shared_level)
5309 			goto out;
5310 
5311 		ret = find_next_key(path, level + 1, &wc->update_progress);
5312 		if (ret > 0)
5313 			wc->update_ref = 0;
5314 
5315 		wc->stage = DROP_REFERENCE;
5316 		wc->shared_level = -1;
5317 		path->slots[level] = 0;
5318 
5319 		/*
5320 		 * check reference count again if the block isn't locked.
5321 		 * we should start walking down the tree again if reference
5322 		 * count is one.
5323 		 */
5324 		if (!path->locks[level]) {
5325 			BUG_ON(level == 0);
5326 			btrfs_tree_lock(eb);
5327 			path->locks[level] = BTRFS_WRITE_LOCK;
5328 
5329 			ret = btrfs_lookup_extent_info(trans, fs_info,
5330 						       eb->start, level, 1,
5331 						       &wc->refs[level],
5332 						       &wc->flags[level]);
5333 			if (ret < 0) {
5334 				btrfs_tree_unlock_rw(eb, path->locks[level]);
5335 				path->locks[level] = 0;
5336 				return ret;
5337 			}
5338 			BUG_ON(wc->refs[level] == 0);
5339 			if (wc->refs[level] == 1) {
5340 				btrfs_tree_unlock_rw(eb, path->locks[level]);
5341 				path->locks[level] = 0;
5342 				return 1;
5343 			}
5344 		}
5345 	}
5346 
5347 	/* wc->stage == DROP_REFERENCE */
5348 	BUG_ON(wc->refs[level] > 1 && !path->locks[level]);
5349 
5350 	if (wc->refs[level] == 1) {
5351 		if (level == 0) {
5352 			if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
5353 				ret = btrfs_dec_ref(trans, root, eb, 1);
5354 			else
5355 				ret = btrfs_dec_ref(trans, root, eb, 0);
5356 			BUG_ON(ret); /* -ENOMEM */
5357 			if (is_fstree(root->root_key.objectid)) {
5358 				ret = btrfs_qgroup_trace_leaf_items(trans, eb);
5359 				if (ret) {
5360 					btrfs_err_rl(fs_info,
5361 	"error %d accounting leaf items, quota is out of sync, rescan required",
5362 					     ret);
5363 				}
5364 			}
5365 		}
5366 		/* make block locked assertion in btrfs_clean_tree_block happy */
5367 		if (!path->locks[level] &&
5368 		    btrfs_header_generation(eb) == trans->transid) {
5369 			btrfs_tree_lock(eb);
5370 			path->locks[level] = BTRFS_WRITE_LOCK;
5371 		}
5372 		btrfs_clean_tree_block(eb);
5373 	}
5374 
5375 	if (eb == root->node) {
5376 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
5377 			parent = eb->start;
5378 		else if (root->root_key.objectid != btrfs_header_owner(eb))
5379 			goto owner_mismatch;
5380 	} else {
5381 		if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
5382 			parent = path->nodes[level + 1]->start;
5383 		else if (root->root_key.objectid !=
5384 			 btrfs_header_owner(path->nodes[level + 1]))
5385 			goto owner_mismatch;
5386 	}
5387 
5388 	btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1);
5389 out:
5390 	wc->refs[level] = 0;
5391 	wc->flags[level] = 0;
5392 	return 0;
5393 
5394 owner_mismatch:
5395 	btrfs_err_rl(fs_info, "unexpected tree owner, have %llu expect %llu",
5396 		     btrfs_header_owner(eb), root->root_key.objectid);
5397 	return -EUCLEAN;
5398 }
5399 
5400 static noinline int walk_down_tree(struct btrfs_trans_handle *trans,
5401 				   struct btrfs_root *root,
5402 				   struct btrfs_path *path,
5403 				   struct walk_control *wc)
5404 {
5405 	int level = wc->level;
5406 	int lookup_info = 1;
5407 	int ret;
5408 
5409 	while (level >= 0) {
5410 		ret = walk_down_proc(trans, root, path, wc, lookup_info);
5411 		if (ret > 0)
5412 			break;
5413 
5414 		if (level == 0)
5415 			break;
5416 
5417 		if (path->slots[level] >=
5418 		    btrfs_header_nritems(path->nodes[level]))
5419 			break;
5420 
5421 		ret = do_walk_down(trans, root, path, wc, &lookup_info);
5422 		if (ret > 0) {
5423 			path->slots[level]++;
5424 			continue;
5425 		} else if (ret < 0)
5426 			return ret;
5427 		level = wc->level;
5428 	}
5429 	return 0;
5430 }
5431 
5432 static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
5433 				 struct btrfs_root *root,
5434 				 struct btrfs_path *path,
5435 				 struct walk_control *wc, int max_level)
5436 {
5437 	int level = wc->level;
5438 	int ret;
5439 
5440 	path->slots[level] = btrfs_header_nritems(path->nodes[level]);
5441 	while (level < max_level && path->nodes[level]) {
5442 		wc->level = level;
5443 		if (path->slots[level] + 1 <
5444 		    btrfs_header_nritems(path->nodes[level])) {
5445 			path->slots[level]++;
5446 			return 0;
5447 		} else {
5448 			ret = walk_up_proc(trans, root, path, wc);
5449 			if (ret > 0)
5450 				return 0;
5451 			if (ret < 0)
5452 				return ret;
5453 
5454 			if (path->locks[level]) {
5455 				btrfs_tree_unlock_rw(path->nodes[level],
5456 						     path->locks[level]);
5457 				path->locks[level] = 0;
5458 			}
5459 			free_extent_buffer(path->nodes[level]);
5460 			path->nodes[level] = NULL;
5461 			level++;
5462 		}
5463 	}
5464 	return 1;
5465 }
5466 
5467 /*
5468  * drop a subvolume tree.
5469  *
5470  * this function traverses the tree freeing any blocks that only
5471  * referenced by the tree.
5472  *
5473  * when a shared tree block is found. this function decreases its
5474  * reference count by one. if update_ref is true, this function
5475  * also make sure backrefs for the shared block and all lower level
5476  * blocks are properly updated.
5477  *
5478  * If called with for_reloc == 0, may exit early with -EAGAIN
5479  */
5480 int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc)
5481 {
5482 	struct btrfs_fs_info *fs_info = root->fs_info;
5483 	struct btrfs_path *path;
5484 	struct btrfs_trans_handle *trans;
5485 	struct btrfs_root *tree_root = fs_info->tree_root;
5486 	struct btrfs_root_item *root_item = &root->root_item;
5487 	struct walk_control *wc;
5488 	struct btrfs_key key;
5489 	int err = 0;
5490 	int ret;
5491 	int level;
5492 	bool root_dropped = false;
5493 
5494 	btrfs_debug(fs_info, "Drop subvolume %llu", root->root_key.objectid);
5495 
5496 	path = btrfs_alloc_path();
5497 	if (!path) {
5498 		err = -ENOMEM;
5499 		goto out;
5500 	}
5501 
5502 	wc = kzalloc(sizeof(*wc), GFP_NOFS);
5503 	if (!wc) {
5504 		btrfs_free_path(path);
5505 		err = -ENOMEM;
5506 		goto out;
5507 	}
5508 
5509 	/*
5510 	 * Use join to avoid potential EINTR from transaction start. See
5511 	 * wait_reserve_ticket and the whole reservation callchain.
5512 	 */
5513 	if (for_reloc)
5514 		trans = btrfs_join_transaction(tree_root);
5515 	else
5516 		trans = btrfs_start_transaction(tree_root, 0);
5517 	if (IS_ERR(trans)) {
5518 		err = PTR_ERR(trans);
5519 		goto out_free;
5520 	}
5521 
5522 	err = btrfs_run_delayed_items(trans);
5523 	if (err)
5524 		goto out_end_trans;
5525 
5526 	/*
5527 	 * This will help us catch people modifying the fs tree while we're
5528 	 * dropping it.  It is unsafe to mess with the fs tree while it's being
5529 	 * dropped as we unlock the root node and parent nodes as we walk down
5530 	 * the tree, assuming nothing will change.  If something does change
5531 	 * then we'll have stale information and drop references to blocks we've
5532 	 * already dropped.
5533 	 */
5534 	set_bit(BTRFS_ROOT_DELETING, &root->state);
5535 	if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
5536 		level = btrfs_header_level(root->node);
5537 		path->nodes[level] = btrfs_lock_root_node(root);
5538 		path->slots[level] = 0;
5539 		path->locks[level] = BTRFS_WRITE_LOCK;
5540 		memset(&wc->update_progress, 0,
5541 		       sizeof(wc->update_progress));
5542 	} else {
5543 		btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
5544 		memcpy(&wc->update_progress, &key,
5545 		       sizeof(wc->update_progress));
5546 
5547 		level = btrfs_root_drop_level(root_item);
5548 		BUG_ON(level == 0);
5549 		path->lowest_level = level;
5550 		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5551 		path->lowest_level = 0;
5552 		if (ret < 0) {
5553 			err = ret;
5554 			goto out_end_trans;
5555 		}
5556 		WARN_ON(ret > 0);
5557 
5558 		/*
5559 		 * unlock our path, this is safe because only this
5560 		 * function is allowed to delete this snapshot
5561 		 */
5562 		btrfs_unlock_up_safe(path, 0);
5563 
5564 		level = btrfs_header_level(root->node);
5565 		while (1) {
5566 			btrfs_tree_lock(path->nodes[level]);
5567 			path->locks[level] = BTRFS_WRITE_LOCK;
5568 
5569 			ret = btrfs_lookup_extent_info(trans, fs_info,
5570 						path->nodes[level]->start,
5571 						level, 1, &wc->refs[level],
5572 						&wc->flags[level]);
5573 			if (ret < 0) {
5574 				err = ret;
5575 				goto out_end_trans;
5576 			}
5577 			BUG_ON(wc->refs[level] == 0);
5578 
5579 			if (level == btrfs_root_drop_level(root_item))
5580 				break;
5581 
5582 			btrfs_tree_unlock(path->nodes[level]);
5583 			path->locks[level] = 0;
5584 			WARN_ON(wc->refs[level] != 1);
5585 			level--;
5586 		}
5587 	}
5588 
5589 	wc->restarted = test_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
5590 	wc->level = level;
5591 	wc->shared_level = -1;
5592 	wc->stage = DROP_REFERENCE;
5593 	wc->update_ref = update_ref;
5594 	wc->keep_locks = 0;
5595 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);
5596 
5597 	while (1) {
5598 
5599 		ret = walk_down_tree(trans, root, path, wc);
5600 		if (ret < 0) {
5601 			err = ret;
5602 			break;
5603 		}
5604 
5605 		ret = walk_up_tree(trans, root, path, wc, BTRFS_MAX_LEVEL);
5606 		if (ret < 0) {
5607 			err = ret;
5608 			break;
5609 		}
5610 
5611 		if (ret > 0) {
5612 			BUG_ON(wc->stage != DROP_REFERENCE);
5613 			break;
5614 		}
5615 
5616 		if (wc->stage == DROP_REFERENCE) {
5617 			wc->drop_level = wc->level;
5618 			btrfs_node_key_to_cpu(path->nodes[wc->drop_level],
5619 					      &wc->drop_progress,
5620 					      path->slots[wc->drop_level]);
5621 		}
5622 		btrfs_cpu_key_to_disk(&root_item->drop_progress,
5623 				      &wc->drop_progress);
5624 		btrfs_set_root_drop_level(root_item, wc->drop_level);
5625 
5626 		BUG_ON(wc->level == 0);
5627 		if (btrfs_should_end_transaction(trans) ||
5628 		    (!for_reloc && btrfs_need_cleaner_sleep(fs_info))) {
5629 			ret = btrfs_update_root(trans, tree_root,
5630 						&root->root_key,
5631 						root_item);
5632 			if (ret) {
5633 				btrfs_abort_transaction(trans, ret);
5634 				err = ret;
5635 				goto out_end_trans;
5636 			}
5637 
5638 			btrfs_end_transaction_throttle(trans);
5639 			if (!for_reloc && btrfs_need_cleaner_sleep(fs_info)) {
5640 				btrfs_debug(fs_info,
5641 					    "drop snapshot early exit");
5642 				err = -EAGAIN;
5643 				goto out_free;
5644 			}
5645 
5646 		       /*
5647 			* Use join to avoid potential EINTR from transaction
5648 			* start. See wait_reserve_ticket and the whole
5649 			* reservation callchain.
5650 			*/
5651 			if (for_reloc)
5652 				trans = btrfs_join_transaction(tree_root);
5653 			else
5654 				trans = btrfs_start_transaction(tree_root, 0);
5655 			if (IS_ERR(trans)) {
5656 				err = PTR_ERR(trans);
5657 				goto out_free;
5658 			}
5659 		}
5660 	}
5661 	btrfs_release_path(path);
5662 	if (err)
5663 		goto out_end_trans;
5664 
5665 	ret = btrfs_del_root(trans, &root->root_key);
5666 	if (ret) {
5667 		btrfs_abort_transaction(trans, ret);
5668 		err = ret;
5669 		goto out_end_trans;
5670 	}
5671 
5672 	if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
5673 		ret = btrfs_find_root(tree_root, &root->root_key, path,
5674 				      NULL, NULL);
5675 		if (ret < 0) {
5676 			btrfs_abort_transaction(trans, ret);
5677 			err = ret;
5678 			goto out_end_trans;
5679 		} else if (ret > 0) {
5680 			/* if we fail to delete the orphan item this time
5681 			 * around, it'll get picked up the next time.
5682 			 *
5683 			 * The most common failure here is just -ENOENT.
5684 			 */
5685 			btrfs_del_orphan_item(trans, tree_root,
5686 					      root->root_key.objectid);
5687 		}
5688 	}
5689 
5690 	/*
5691 	 * This subvolume is going to be completely dropped, and won't be
5692 	 * recorded as dirty roots, thus pertrans meta rsv will not be freed at
5693 	 * commit transaction time.  So free it here manually.
5694 	 */
5695 	btrfs_qgroup_convert_reserved_meta(root, INT_MAX);
5696 	btrfs_qgroup_free_meta_all_pertrans(root);
5697 
5698 	if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state))
5699 		btrfs_add_dropped_root(trans, root);
5700 	else
5701 		btrfs_put_root(root);
5702 	root_dropped = true;
5703 out_end_trans:
5704 	btrfs_end_transaction_throttle(trans);
5705 out_free:
5706 	kfree(wc);
5707 	btrfs_free_path(path);
5708 out:
5709 	/*
5710 	 * So if we need to stop dropping the snapshot for whatever reason we
5711 	 * need to make sure to add it back to the dead root list so that we
5712 	 * keep trying to do the work later.  This also cleans up roots if we
5713 	 * don't have it in the radix (like when we recover after a power fail
5714 	 * or unmount) so we don't leak memory.
5715 	 */
5716 	if (!for_reloc && !root_dropped)
5717 		btrfs_add_dead_root(root);
5718 	return err;
5719 }
5720 
5721 /*
5722  * drop subtree rooted at tree block 'node'.
5723  *
5724  * NOTE: this function will unlock and release tree block 'node'
5725  * only used by relocation code
5726  */
5727 int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
5728 			struct btrfs_root *root,
5729 			struct extent_buffer *node,
5730 			struct extent_buffer *parent)
5731 {
5732 	struct btrfs_fs_info *fs_info = root->fs_info;
5733 	struct btrfs_path *path;
5734 	struct walk_control *wc;
5735 	int level;
5736 	int parent_level;
5737 	int ret = 0;
5738 	int wret;
5739 
5740 	BUG_ON(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
5741 
5742 	path = btrfs_alloc_path();
5743 	if (!path)
5744 		return -ENOMEM;
5745 
5746 	wc = kzalloc(sizeof(*wc), GFP_NOFS);
5747 	if (!wc) {
5748 		btrfs_free_path(path);
5749 		return -ENOMEM;
5750 	}
5751 
5752 	btrfs_assert_tree_locked(parent);
5753 	parent_level = btrfs_header_level(parent);
5754 	atomic_inc(&parent->refs);
5755 	path->nodes[parent_level] = parent;
5756 	path->slots[parent_level] = btrfs_header_nritems(parent);
5757 
5758 	btrfs_assert_tree_locked(node);
5759 	level = btrfs_header_level(node);
5760 	path->nodes[level] = node;
5761 	path->slots[level] = 0;
5762 	path->locks[level] = BTRFS_WRITE_LOCK;
5763 
5764 	wc->refs[parent_level] = 1;
5765 	wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;
5766 	wc->level = level;
5767 	wc->shared_level = -1;
5768 	wc->stage = DROP_REFERENCE;
5769 	wc->update_ref = 0;
5770 	wc->keep_locks = 1;
5771 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);
5772 
5773 	while (1) {
5774 		wret = walk_down_tree(trans, root, path, wc);
5775 		if (wret < 0) {
5776 			ret = wret;
5777 			break;
5778 		}
5779 
5780 		wret = walk_up_tree(trans, root, path, wc, parent_level);
5781 		if (wret < 0)
5782 			ret = wret;
5783 		if (wret != 0)
5784 			break;
5785 	}
5786 
5787 	kfree(wc);
5788 	btrfs_free_path(path);
5789 	return ret;
5790 }
5791 
5792 /*
5793  * helper to account the unused space of all the readonly block group in the
5794  * space_info. takes mirrors into account.
5795  */
5796 u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
5797 {
5798 	struct btrfs_block_group *block_group;
5799 	u64 free_bytes = 0;
5800 	int factor;
5801 
5802 	/* It's df, we don't care if it's racy */
5803 	if (list_empty(&sinfo->ro_bgs))
5804 		return 0;
5805 
5806 	spin_lock(&sinfo->lock);
5807 	list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
5808 		spin_lock(&block_group->lock);
5809 
5810 		if (!block_group->ro) {
5811 			spin_unlock(&block_group->lock);
5812 			continue;
5813 		}
5814 
5815 		factor = btrfs_bg_type_to_factor(block_group->flags);
5816 		free_bytes += (block_group->length -
5817 			       block_group->used) * factor;
5818 
5819 		spin_unlock(&block_group->lock);
5820 	}
5821 	spin_unlock(&sinfo->lock);
5822 
5823 	return free_bytes;
5824 }
5825 
5826 int btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info,
5827 				   u64 start, u64 end)
5828 {
5829 	return unpin_extent_range(fs_info, start, end, false);
5830 }
5831 
5832 /*
5833  * It used to be that old block groups would be left around forever.
5834  * Iterating over them would be enough to trim unused space.  Since we
5835  * now automatically remove them, we also need to iterate over unallocated
5836  * space.
5837  *
5838  * We don't want a transaction for this since the discard may take a
5839  * substantial amount of time.  We don't require that a transaction be
5840  * running, but we do need to take a running transaction into account
5841  * to ensure that we're not discarding chunks that were released or
5842  * allocated in the current transaction.
5843  *
5844  * Holding the chunks lock will prevent other threads from allocating
5845  * or releasing chunks, but it won't prevent a running transaction
5846  * from committing and releasing the memory that the pending chunks
5847  * list head uses.  For that, we need to take a reference to the
5848  * transaction and hold the commit root sem.  We only need to hold
5849  * it while performing the free space search since we have already
5850  * held back allocations.
5851  */
5852 static int btrfs_trim_free_extents(struct btrfs_device *device, u64 *trimmed)
5853 {
5854 	u64 start = SZ_1M, len = 0, end = 0;
5855 	int ret;
5856 
5857 	*trimmed = 0;
5858 
5859 	/* Discard not supported = nothing to do. */
5860 	if (!blk_queue_discard(bdev_get_queue(device->bdev)))
5861 		return 0;
5862 
5863 	/* Not writable = nothing to do. */
5864 	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
5865 		return 0;
5866 
5867 	/* No free space = nothing to do. */
5868 	if (device->total_bytes <= device->bytes_used)
5869 		return 0;
5870 
5871 	ret = 0;
5872 
5873 	while (1) {
5874 		struct btrfs_fs_info *fs_info = device->fs_info;
5875 		u64 bytes;
5876 
5877 		ret = mutex_lock_interruptible(&fs_info->chunk_mutex);
5878 		if (ret)
5879 			break;
5880 
5881 		find_first_clear_extent_bit(&device->alloc_state, start,
5882 					    &start, &end,
5883 					    CHUNK_TRIMMED | CHUNK_ALLOCATED);
5884 
5885 		/* Check if there are any CHUNK_* bits left */
5886 		if (start > device->total_bytes) {
5887 			WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
5888 			btrfs_warn_in_rcu(fs_info,
5889 "ignoring attempt to trim beyond device size: offset %llu length %llu device %s device size %llu",
5890 					  start, end - start + 1,
5891 					  rcu_str_deref(device->name),
5892 					  device->total_bytes);
5893 			mutex_unlock(&fs_info->chunk_mutex);
5894 			ret = 0;
5895 			break;
5896 		}
5897 
5898 		/* Ensure we skip the reserved area in the first 1M */
5899 		start = max_t(u64, start, SZ_1M);
5900 
5901 		/*
5902 		 * If find_first_clear_extent_bit find a range that spans the
5903 		 * end of the device it will set end to -1, in this case it's up
5904 		 * to the caller to trim the value to the size of the device.
5905 		 */
5906 		end = min(end, device->total_bytes - 1);
5907 
5908 		len = end - start + 1;
5909 
5910 		/* We didn't find any extents */
5911 		if (!len) {
5912 			mutex_unlock(&fs_info->chunk_mutex);
5913 			ret = 0;
5914 			break;
5915 		}
5916 
5917 		ret = btrfs_issue_discard(device->bdev, start, len,
5918 					  &bytes);
5919 		if (!ret)
5920 			set_extent_bits(&device->alloc_state, start,
5921 					start + bytes - 1,
5922 					CHUNK_TRIMMED);
5923 		mutex_unlock(&fs_info->chunk_mutex);
5924 
5925 		if (ret)
5926 			break;
5927 
5928 		start += len;
5929 		*trimmed += bytes;
5930 
5931 		if (fatal_signal_pending(current)) {
5932 			ret = -ERESTARTSYS;
5933 			break;
5934 		}
5935 
5936 		cond_resched();
5937 	}
5938 
5939 	return ret;
5940 }
5941 
5942 /*
5943  * Trim the whole filesystem by:
5944  * 1) trimming the free space in each block group
5945  * 2) trimming the unallocated space on each device
5946  *
5947  * This will also continue trimming even if a block group or device encounters
5948  * an error.  The return value will be the last error, or 0 if nothing bad
5949  * happens.
5950  */
5951 int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
5952 {
5953 	struct btrfs_block_group *cache = NULL;
5954 	struct btrfs_device *device;
5955 	struct list_head *devices;
5956 	u64 group_trimmed;
5957 	u64 range_end = U64_MAX;
5958 	u64 start;
5959 	u64 end;
5960 	u64 trimmed = 0;
5961 	u64 bg_failed = 0;
5962 	u64 dev_failed = 0;
5963 	int bg_ret = 0;
5964 	int dev_ret = 0;
5965 	int ret = 0;
5966 
5967 	/*
5968 	 * Check range overflow if range->len is set.
5969 	 * The default range->len is U64_MAX.
5970 	 */
5971 	if (range->len != U64_MAX &&
5972 	    check_add_overflow(range->start, range->len, &range_end))
5973 		return -EINVAL;
5974 
5975 	cache = btrfs_lookup_first_block_group(fs_info, range->start);
5976 	for (; cache; cache = btrfs_next_block_group(cache)) {
5977 		if (cache->start >= range_end) {
5978 			btrfs_put_block_group(cache);
5979 			break;
5980 		}
5981 
5982 		start = max(range->start, cache->start);
5983 		end = min(range_end, cache->start + cache->length);
5984 
5985 		if (end - start >= range->minlen) {
5986 			if (!btrfs_block_group_done(cache)) {
5987 				ret = btrfs_cache_block_group(cache, 0);
5988 				if (ret) {
5989 					bg_failed++;
5990 					bg_ret = ret;
5991 					continue;
5992 				}
5993 				ret = btrfs_wait_block_group_cache_done(cache);
5994 				if (ret) {
5995 					bg_failed++;
5996 					bg_ret = ret;
5997 					continue;
5998 				}
5999 			}
6000 			ret = btrfs_trim_block_group(cache,
6001 						     &group_trimmed,
6002 						     start,
6003 						     end,
6004 						     range->minlen);
6005 
6006 			trimmed += group_trimmed;
6007 			if (ret) {
6008 				bg_failed++;
6009 				bg_ret = ret;
6010 				continue;
6011 			}
6012 		}
6013 	}
6014 
6015 	if (bg_failed)
6016 		btrfs_warn(fs_info,
6017 			"failed to trim %llu block group(s), last error %d",
6018 			bg_failed, bg_ret);
6019 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
6020 	devices = &fs_info->fs_devices->devices;
6021 	list_for_each_entry(device, devices, dev_list) {
6022 		if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
6023 			continue;
6024 
6025 		ret = btrfs_trim_free_extents(device, &group_trimmed);
6026 		if (ret) {
6027 			dev_failed++;
6028 			dev_ret = ret;
6029 			break;
6030 		}
6031 
6032 		trimmed += group_trimmed;
6033 	}
6034 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
6035 
6036 	if (dev_failed)
6037 		btrfs_warn(fs_info,
6038 			"failed to trim %llu device(s), last error %d",
6039 			dev_failed, dev_ret);
6040 	range->len = trimmed;
6041 	if (bg_ret)
6042 		return bg_ret;
6043 	return dev_ret;
6044 }
6045