xref: /openbmc/linux/fs/btrfs/disk-io.c (revision 275876e2)
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 
19 #include <linux/fs.h>
20 #include <linux/blkdev.h>
21 #include <linux/scatterlist.h>
22 #include <linux/swap.h>
23 #include <linux/radix-tree.h>
24 #include <linux/writeback.h>
25 #include <linux/buffer_head.h>
26 #include <linux/workqueue.h>
27 #include <linux/kthread.h>
28 #include <linux/freezer.h>
29 #include <linux/slab.h>
30 #include <linux/migrate.h>
31 #include <linux/ratelimit.h>
32 #include <linux/uuid.h>
33 #include <linux/semaphore.h>
34 #include <asm/unaligned.h>
35 #include "ctree.h"
36 #include "disk-io.h"
37 #include "hash.h"
38 #include "transaction.h"
39 #include "btrfs_inode.h"
40 #include "volumes.h"
41 #include "print-tree.h"
42 #include "async-thread.h"
43 #include "locking.h"
44 #include "tree-log.h"
45 #include "free-space-cache.h"
46 #include "inode-map.h"
47 #include "check-integrity.h"
48 #include "rcu-string.h"
49 #include "dev-replace.h"
50 #include "raid56.h"
51 #include "sysfs.h"
52 #include "qgroup.h"
53 
54 #ifdef CONFIG_X86
55 #include <asm/cpufeature.h>
56 #endif
57 
58 static struct extent_io_ops btree_extent_io_ops;
59 static void end_workqueue_fn(struct btrfs_work *work);
60 static void free_fs_root(struct btrfs_root *root);
61 static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
62 				    int read_only);
63 static void btrfs_destroy_ordered_extents(struct btrfs_root *root);
64 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
65 				      struct btrfs_root *root);
66 static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root);
67 static int btrfs_destroy_marked_extents(struct btrfs_root *root,
68 					struct extent_io_tree *dirty_pages,
69 					int mark);
70 static int btrfs_destroy_pinned_extent(struct btrfs_root *root,
71 				       struct extent_io_tree *pinned_extents);
72 static int btrfs_cleanup_transaction(struct btrfs_root *root);
73 static void btrfs_error_commit_super(struct btrfs_root *root);
74 
75 /*
76  * end_io_wq structs are used to do processing in task context when an IO is
77  * complete.  This is used during reads to verify checksums, and it is used
78  * by writes to insert metadata for new file extents after IO is complete.
79  */
80 struct end_io_wq {
81 	struct bio *bio;
82 	bio_end_io_t *end_io;
83 	void *private;
84 	struct btrfs_fs_info *info;
85 	int error;
86 	int metadata;
87 	struct list_head list;
88 	struct btrfs_work work;
89 };
90 
91 /*
92  * async submit bios are used to offload expensive checksumming
93  * onto the worker threads.  They checksum file and metadata bios
94  * just before they are sent down the IO stack.
95  */
96 struct async_submit_bio {
97 	struct inode *inode;
98 	struct bio *bio;
99 	struct list_head list;
100 	extent_submit_bio_hook_t *submit_bio_start;
101 	extent_submit_bio_hook_t *submit_bio_done;
102 	int rw;
103 	int mirror_num;
104 	unsigned long bio_flags;
105 	/*
106 	 * bio_offset is optional, can be used if the pages in the bio
107 	 * can't tell us where in the file the bio should go
108 	 */
109 	u64 bio_offset;
110 	struct btrfs_work work;
111 	int error;
112 };
113 
114 /*
115  * Lockdep class keys for extent_buffer->lock's in this root.  For a given
116  * eb, the lockdep key is determined by the btrfs_root it belongs to and
117  * the level the eb occupies in the tree.
118  *
119  * Different roots are used for different purposes and may nest inside each
120  * other and they require separate keysets.  As lockdep keys should be
121  * static, assign keysets according to the purpose of the root as indicated
122  * by btrfs_root->objectid.  This ensures that all special purpose roots
123  * have separate keysets.
124  *
125  * Lock-nesting across peer nodes is always done with the immediate parent
126  * node locked thus preventing deadlock.  As lockdep doesn't know this, use
127  * subclass to avoid triggering lockdep warning in such cases.
128  *
129  * The key is set by the readpage_end_io_hook after the buffer has passed
130  * csum validation but before the pages are unlocked.  It is also set by
131  * btrfs_init_new_buffer on freshly allocated blocks.
132  *
133  * We also add a check to make sure the highest level of the tree is the
134  * same as our lockdep setup here.  If BTRFS_MAX_LEVEL changes, this code
135  * needs update as well.
136  */
137 #ifdef CONFIG_DEBUG_LOCK_ALLOC
138 # if BTRFS_MAX_LEVEL != 8
139 #  error
140 # endif
141 
142 static struct btrfs_lockdep_keyset {
143 	u64			id;		/* root objectid */
144 	const char		*name_stem;	/* lock name stem */
145 	char			names[BTRFS_MAX_LEVEL + 1][20];
146 	struct lock_class_key	keys[BTRFS_MAX_LEVEL + 1];
147 } btrfs_lockdep_keysets[] = {
148 	{ .id = BTRFS_ROOT_TREE_OBJECTID,	.name_stem = "root"	},
149 	{ .id = BTRFS_EXTENT_TREE_OBJECTID,	.name_stem = "extent"	},
150 	{ .id = BTRFS_CHUNK_TREE_OBJECTID,	.name_stem = "chunk"	},
151 	{ .id = BTRFS_DEV_TREE_OBJECTID,	.name_stem = "dev"	},
152 	{ .id = BTRFS_FS_TREE_OBJECTID,		.name_stem = "fs"	},
153 	{ .id = BTRFS_CSUM_TREE_OBJECTID,	.name_stem = "csum"	},
154 	{ .id = BTRFS_QUOTA_TREE_OBJECTID,	.name_stem = "quota"	},
155 	{ .id = BTRFS_TREE_LOG_OBJECTID,	.name_stem = "log"	},
156 	{ .id = BTRFS_TREE_RELOC_OBJECTID,	.name_stem = "treloc"	},
157 	{ .id = BTRFS_DATA_RELOC_TREE_OBJECTID,	.name_stem = "dreloc"	},
158 	{ .id = BTRFS_UUID_TREE_OBJECTID,	.name_stem = "uuid"	},
159 	{ .id = 0,				.name_stem = "tree"	},
160 };
161 
162 void __init btrfs_init_lockdep(void)
163 {
164 	int i, j;
165 
166 	/* initialize lockdep class names */
167 	for (i = 0; i < ARRAY_SIZE(btrfs_lockdep_keysets); i++) {
168 		struct btrfs_lockdep_keyset *ks = &btrfs_lockdep_keysets[i];
169 
170 		for (j = 0; j < ARRAY_SIZE(ks->names); j++)
171 			snprintf(ks->names[j], sizeof(ks->names[j]),
172 				 "btrfs-%s-%02d", ks->name_stem, j);
173 	}
174 }
175 
176 void btrfs_set_buffer_lockdep_class(u64 objectid, struct extent_buffer *eb,
177 				    int level)
178 {
179 	struct btrfs_lockdep_keyset *ks;
180 
181 	BUG_ON(level >= ARRAY_SIZE(ks->keys));
182 
183 	/* find the matching keyset, id 0 is the default entry */
184 	for (ks = btrfs_lockdep_keysets; ks->id; ks++)
185 		if (ks->id == objectid)
186 			break;
187 
188 	lockdep_set_class_and_name(&eb->lock,
189 				   &ks->keys[level], ks->names[level]);
190 }
191 
192 #endif
193 
194 /*
195  * extents on the btree inode are pretty simple, there's one extent
196  * that covers the entire device
197  */
198 static struct extent_map *btree_get_extent(struct inode *inode,
199 		struct page *page, size_t pg_offset, u64 start, u64 len,
200 		int create)
201 {
202 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
203 	struct extent_map *em;
204 	int ret;
205 
206 	read_lock(&em_tree->lock);
207 	em = lookup_extent_mapping(em_tree, start, len);
208 	if (em) {
209 		em->bdev =
210 			BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
211 		read_unlock(&em_tree->lock);
212 		goto out;
213 	}
214 	read_unlock(&em_tree->lock);
215 
216 	em = alloc_extent_map();
217 	if (!em) {
218 		em = ERR_PTR(-ENOMEM);
219 		goto out;
220 	}
221 	em->start = 0;
222 	em->len = (u64)-1;
223 	em->block_len = (u64)-1;
224 	em->block_start = 0;
225 	em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
226 
227 	write_lock(&em_tree->lock);
228 	ret = add_extent_mapping(em_tree, em, 0);
229 	if (ret == -EEXIST) {
230 		free_extent_map(em);
231 		em = lookup_extent_mapping(em_tree, start, len);
232 		if (!em)
233 			em = ERR_PTR(-EIO);
234 	} else if (ret) {
235 		free_extent_map(em);
236 		em = ERR_PTR(ret);
237 	}
238 	write_unlock(&em_tree->lock);
239 
240 out:
241 	return em;
242 }
243 
244 u32 btrfs_csum_data(char *data, u32 seed, size_t len)
245 {
246 	return btrfs_crc32c(seed, data, len);
247 }
248 
249 void btrfs_csum_final(u32 crc, char *result)
250 {
251 	put_unaligned_le32(~crc, result);
252 }
253 
254 /*
255  * compute the csum for a btree block, and either verify it or write it
256  * into the csum field of the block.
257  */
258 static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
259 			   int verify)
260 {
261 	u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
262 	char *result = NULL;
263 	unsigned long len;
264 	unsigned long cur_len;
265 	unsigned long offset = BTRFS_CSUM_SIZE;
266 	char *kaddr;
267 	unsigned long map_start;
268 	unsigned long map_len;
269 	int err;
270 	u32 crc = ~(u32)0;
271 	unsigned long inline_result;
272 
273 	len = buf->len - offset;
274 	while (len > 0) {
275 		err = map_private_extent_buffer(buf, offset, 32,
276 					&kaddr, &map_start, &map_len);
277 		if (err)
278 			return 1;
279 		cur_len = min(len, map_len - (offset - map_start));
280 		crc = btrfs_csum_data(kaddr + offset - map_start,
281 				      crc, cur_len);
282 		len -= cur_len;
283 		offset += cur_len;
284 	}
285 	if (csum_size > sizeof(inline_result)) {
286 		result = kzalloc(csum_size * sizeof(char), GFP_NOFS);
287 		if (!result)
288 			return 1;
289 	} else {
290 		result = (char *)&inline_result;
291 	}
292 
293 	btrfs_csum_final(crc, result);
294 
295 	if (verify) {
296 		if (memcmp_extent_buffer(buf, result, 0, csum_size)) {
297 			u32 val;
298 			u32 found = 0;
299 			memcpy(&found, result, csum_size);
300 
301 			read_extent_buffer(buf, &val, 0, csum_size);
302 			printk_ratelimited(KERN_INFO
303 				"BTRFS: %s checksum verify failed on %llu wanted %X found %X "
304 				"level %d\n",
305 				root->fs_info->sb->s_id, buf->start,
306 				val, found, btrfs_header_level(buf));
307 			if (result != (char *)&inline_result)
308 				kfree(result);
309 			return 1;
310 		}
311 	} else {
312 		write_extent_buffer(buf, result, 0, csum_size);
313 	}
314 	if (result != (char *)&inline_result)
315 		kfree(result);
316 	return 0;
317 }
318 
319 /*
320  * we can't consider a given block up to date unless the transid of the
321  * block matches the transid in the parent node's pointer.  This is how we
322  * detect blocks that either didn't get written at all or got written
323  * in the wrong place.
324  */
325 static int verify_parent_transid(struct extent_io_tree *io_tree,
326 				 struct extent_buffer *eb, u64 parent_transid,
327 				 int atomic)
328 {
329 	struct extent_state *cached_state = NULL;
330 	int ret;
331 	bool need_lock = (current->journal_info ==
332 			  (void *)BTRFS_SEND_TRANS_STUB);
333 
334 	if (!parent_transid || btrfs_header_generation(eb) == parent_transid)
335 		return 0;
336 
337 	if (atomic)
338 		return -EAGAIN;
339 
340 	if (need_lock) {
341 		btrfs_tree_read_lock(eb);
342 		btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
343 	}
344 
345 	lock_extent_bits(io_tree, eb->start, eb->start + eb->len - 1,
346 			 0, &cached_state);
347 	if (extent_buffer_uptodate(eb) &&
348 	    btrfs_header_generation(eb) == parent_transid) {
349 		ret = 0;
350 		goto out;
351 	}
352 	printk_ratelimited("parent transid verify failed on %llu wanted %llu "
353 		       "found %llu\n",
354 		       eb->start, parent_transid, btrfs_header_generation(eb));
355 	ret = 1;
356 
357 	/*
358 	 * Things reading via commit roots that don't have normal protection,
359 	 * like send, can have a really old block in cache that may point at a
360 	 * block that has been free'd and re-allocated.  So don't clear uptodate
361 	 * if we find an eb that is under IO (dirty/writeback) because we could
362 	 * end up reading in the stale data and then writing it back out and
363 	 * making everybody very sad.
364 	 */
365 	if (!extent_buffer_under_io(eb))
366 		clear_extent_buffer_uptodate(eb);
367 out:
368 	unlock_extent_cached(io_tree, eb->start, eb->start + eb->len - 1,
369 			     &cached_state, GFP_NOFS);
370 	if (need_lock)
371 		btrfs_tree_read_unlock_blocking(eb);
372 	return ret;
373 }
374 
375 /*
376  * Return 0 if the superblock checksum type matches the checksum value of that
377  * algorithm. Pass the raw disk superblock data.
378  */
379 static int btrfs_check_super_csum(char *raw_disk_sb)
380 {
381 	struct btrfs_super_block *disk_sb =
382 		(struct btrfs_super_block *)raw_disk_sb;
383 	u16 csum_type = btrfs_super_csum_type(disk_sb);
384 	int ret = 0;
385 
386 	if (csum_type == BTRFS_CSUM_TYPE_CRC32) {
387 		u32 crc = ~(u32)0;
388 		const int csum_size = sizeof(crc);
389 		char result[csum_size];
390 
391 		/*
392 		 * The super_block structure does not span the whole
393 		 * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space
394 		 * is filled with zeros and is included in the checkum.
395 		 */
396 		crc = btrfs_csum_data(raw_disk_sb + BTRFS_CSUM_SIZE,
397 				crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
398 		btrfs_csum_final(crc, result);
399 
400 		if (memcmp(raw_disk_sb, result, csum_size))
401 			ret = 1;
402 
403 		if (ret && btrfs_super_generation(disk_sb) < 10) {
404 			printk(KERN_WARNING
405 				"BTRFS: super block crcs don't match, older mkfs detected\n");
406 			ret = 0;
407 		}
408 	}
409 
410 	if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
411 		printk(KERN_ERR "BTRFS: unsupported checksum algorithm %u\n",
412 				csum_type);
413 		ret = 1;
414 	}
415 
416 	return ret;
417 }
418 
419 /*
420  * helper to read a given tree block, doing retries as required when
421  * the checksums don't match and we have alternate mirrors to try.
422  */
423 static int btree_read_extent_buffer_pages(struct btrfs_root *root,
424 					  struct extent_buffer *eb,
425 					  u64 start, u64 parent_transid)
426 {
427 	struct extent_io_tree *io_tree;
428 	int failed = 0;
429 	int ret;
430 	int num_copies = 0;
431 	int mirror_num = 0;
432 	int failed_mirror = 0;
433 
434 	clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
435 	io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
436 	while (1) {
437 		ret = read_extent_buffer_pages(io_tree, eb, start,
438 					       WAIT_COMPLETE,
439 					       btree_get_extent, mirror_num);
440 		if (!ret) {
441 			if (!verify_parent_transid(io_tree, eb,
442 						   parent_transid, 0))
443 				break;
444 			else
445 				ret = -EIO;
446 		}
447 
448 		/*
449 		 * This buffer's crc is fine, but its contents are corrupted, so
450 		 * there is no reason to read the other copies, they won't be
451 		 * any less wrong.
452 		 */
453 		if (test_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags))
454 			break;
455 
456 		num_copies = btrfs_num_copies(root->fs_info,
457 					      eb->start, eb->len);
458 		if (num_copies == 1)
459 			break;
460 
461 		if (!failed_mirror) {
462 			failed = 1;
463 			failed_mirror = eb->read_mirror;
464 		}
465 
466 		mirror_num++;
467 		if (mirror_num == failed_mirror)
468 			mirror_num++;
469 
470 		if (mirror_num > num_copies)
471 			break;
472 	}
473 
474 	if (failed && !ret && failed_mirror)
475 		repair_eb_io_failure(root, eb, failed_mirror);
476 
477 	return ret;
478 }
479 
480 /*
481  * checksum a dirty tree block before IO.  This has extra checks to make sure
482  * we only fill in the checksum field in the first page of a multi-page block
483  */
484 
485 static int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
486 {
487 	u64 start = page_offset(page);
488 	u64 found_start;
489 	struct extent_buffer *eb;
490 
491 	eb = (struct extent_buffer *)page->private;
492 	if (page != eb->pages[0])
493 		return 0;
494 	found_start = btrfs_header_bytenr(eb);
495 	if (WARN_ON(found_start != start || !PageUptodate(page)))
496 		return 0;
497 	csum_tree_block(root, eb, 0);
498 	return 0;
499 }
500 
501 static int check_tree_block_fsid(struct btrfs_root *root,
502 				 struct extent_buffer *eb)
503 {
504 	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
505 	u8 fsid[BTRFS_UUID_SIZE];
506 	int ret = 1;
507 
508 	read_extent_buffer(eb, fsid, btrfs_header_fsid(), BTRFS_FSID_SIZE);
509 	while (fs_devices) {
510 		if (!memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE)) {
511 			ret = 0;
512 			break;
513 		}
514 		fs_devices = fs_devices->seed;
515 	}
516 	return ret;
517 }
518 
519 #define CORRUPT(reason, eb, root, slot)				\
520 	btrfs_crit(root->fs_info, "corrupt leaf, %s: block=%llu,"	\
521 		   "root=%llu, slot=%d", reason,			\
522 	       btrfs_header_bytenr(eb),	root->objectid, slot)
523 
524 static noinline int check_leaf(struct btrfs_root *root,
525 			       struct extent_buffer *leaf)
526 {
527 	struct btrfs_key key;
528 	struct btrfs_key leaf_key;
529 	u32 nritems = btrfs_header_nritems(leaf);
530 	int slot;
531 
532 	if (nritems == 0)
533 		return 0;
534 
535 	/* Check the 0 item */
536 	if (btrfs_item_offset_nr(leaf, 0) + btrfs_item_size_nr(leaf, 0) !=
537 	    BTRFS_LEAF_DATA_SIZE(root)) {
538 		CORRUPT("invalid item offset size pair", leaf, root, 0);
539 		return -EIO;
540 	}
541 
542 	/*
543 	 * Check to make sure each items keys are in the correct order and their
544 	 * offsets make sense.  We only have to loop through nritems-1 because
545 	 * we check the current slot against the next slot, which verifies the
546 	 * next slot's offset+size makes sense and that the current's slot
547 	 * offset is correct.
548 	 */
549 	for (slot = 0; slot < nritems - 1; slot++) {
550 		btrfs_item_key_to_cpu(leaf, &leaf_key, slot);
551 		btrfs_item_key_to_cpu(leaf, &key, slot + 1);
552 
553 		/* Make sure the keys are in the right order */
554 		if (btrfs_comp_cpu_keys(&leaf_key, &key) >= 0) {
555 			CORRUPT("bad key order", leaf, root, slot);
556 			return -EIO;
557 		}
558 
559 		/*
560 		 * Make sure the offset and ends are right, remember that the
561 		 * item data starts at the end of the leaf and grows towards the
562 		 * front.
563 		 */
564 		if (btrfs_item_offset_nr(leaf, slot) !=
565 			btrfs_item_end_nr(leaf, slot + 1)) {
566 			CORRUPT("slot offset bad", leaf, root, slot);
567 			return -EIO;
568 		}
569 
570 		/*
571 		 * Check to make sure that we don't point outside of the leaf,
572 		 * just incase all the items are consistent to eachother, but
573 		 * all point outside of the leaf.
574 		 */
575 		if (btrfs_item_end_nr(leaf, slot) >
576 		    BTRFS_LEAF_DATA_SIZE(root)) {
577 			CORRUPT("slot end outside of leaf", leaf, root, slot);
578 			return -EIO;
579 		}
580 	}
581 
582 	return 0;
583 }
584 
585 static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
586 				      u64 phy_offset, struct page *page,
587 				      u64 start, u64 end, int mirror)
588 {
589 	u64 found_start;
590 	int found_level;
591 	struct extent_buffer *eb;
592 	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
593 	int ret = 0;
594 	int reads_done;
595 
596 	if (!page->private)
597 		goto out;
598 
599 	eb = (struct extent_buffer *)page->private;
600 
601 	/* the pending IO might have been the only thing that kept this buffer
602 	 * in memory.  Make sure we have a ref for all this other checks
603 	 */
604 	extent_buffer_get(eb);
605 
606 	reads_done = atomic_dec_and_test(&eb->io_pages);
607 	if (!reads_done)
608 		goto err;
609 
610 	eb->read_mirror = mirror;
611 	if (test_bit(EXTENT_BUFFER_IOERR, &eb->bflags)) {
612 		ret = -EIO;
613 		goto err;
614 	}
615 
616 	found_start = btrfs_header_bytenr(eb);
617 	if (found_start != eb->start) {
618 		printk_ratelimited(KERN_INFO "BTRFS: bad tree block start "
619 			       "%llu %llu\n",
620 			       found_start, eb->start);
621 		ret = -EIO;
622 		goto err;
623 	}
624 	if (check_tree_block_fsid(root, eb)) {
625 		printk_ratelimited(KERN_INFO "BTRFS: bad fsid on block %llu\n",
626 			       eb->start);
627 		ret = -EIO;
628 		goto err;
629 	}
630 	found_level = btrfs_header_level(eb);
631 	if (found_level >= BTRFS_MAX_LEVEL) {
632 		btrfs_info(root->fs_info, "bad tree block level %d",
633 			   (int)btrfs_header_level(eb));
634 		ret = -EIO;
635 		goto err;
636 	}
637 
638 	btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb),
639 				       eb, found_level);
640 
641 	ret = csum_tree_block(root, eb, 1);
642 	if (ret) {
643 		ret = -EIO;
644 		goto err;
645 	}
646 
647 	/*
648 	 * If this is a leaf block and it is corrupt, set the corrupt bit so
649 	 * that we don't try and read the other copies of this block, just
650 	 * return -EIO.
651 	 */
652 	if (found_level == 0 && check_leaf(root, eb)) {
653 		set_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
654 		ret = -EIO;
655 	}
656 
657 	if (!ret)
658 		set_extent_buffer_uptodate(eb);
659 err:
660 	if (reads_done &&
661 	    test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags))
662 		btree_readahead_hook(root, eb, eb->start, ret);
663 
664 	if (ret) {
665 		/*
666 		 * our io error hook is going to dec the io pages
667 		 * again, we have to make sure it has something
668 		 * to decrement
669 		 */
670 		atomic_inc(&eb->io_pages);
671 		clear_extent_buffer_uptodate(eb);
672 	}
673 	free_extent_buffer(eb);
674 out:
675 	return ret;
676 }
677 
678 static int btree_io_failed_hook(struct page *page, int failed_mirror)
679 {
680 	struct extent_buffer *eb;
681 	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
682 
683 	eb = (struct extent_buffer *)page->private;
684 	set_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
685 	eb->read_mirror = failed_mirror;
686 	atomic_dec(&eb->io_pages);
687 	if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags))
688 		btree_readahead_hook(root, eb, eb->start, -EIO);
689 	return -EIO;	/* we fixed nothing */
690 }
691 
692 static void end_workqueue_bio(struct bio *bio, int err)
693 {
694 	struct end_io_wq *end_io_wq = bio->bi_private;
695 	struct btrfs_fs_info *fs_info;
696 
697 	fs_info = end_io_wq->info;
698 	end_io_wq->error = err;
699 	btrfs_init_work(&end_io_wq->work, end_workqueue_fn, NULL, NULL);
700 
701 	if (bio->bi_rw & REQ_WRITE) {
702 		if (end_io_wq->metadata == BTRFS_WQ_ENDIO_METADATA)
703 			btrfs_queue_work(fs_info->endio_meta_write_workers,
704 					 &end_io_wq->work);
705 		else if (end_io_wq->metadata == BTRFS_WQ_ENDIO_FREE_SPACE)
706 			btrfs_queue_work(fs_info->endio_freespace_worker,
707 					 &end_io_wq->work);
708 		else if (end_io_wq->metadata == BTRFS_WQ_ENDIO_RAID56)
709 			btrfs_queue_work(fs_info->endio_raid56_workers,
710 					 &end_io_wq->work);
711 		else
712 			btrfs_queue_work(fs_info->endio_write_workers,
713 					 &end_io_wq->work);
714 	} else {
715 		if (end_io_wq->metadata == BTRFS_WQ_ENDIO_RAID56)
716 			btrfs_queue_work(fs_info->endio_raid56_workers,
717 					 &end_io_wq->work);
718 		else if (end_io_wq->metadata)
719 			btrfs_queue_work(fs_info->endio_meta_workers,
720 					 &end_io_wq->work);
721 		else
722 			btrfs_queue_work(fs_info->endio_workers,
723 					 &end_io_wq->work);
724 	}
725 }
726 
727 /*
728  * For the metadata arg you want
729  *
730  * 0 - if data
731  * 1 - if normal metadta
732  * 2 - if writing to the free space cache area
733  * 3 - raid parity work
734  */
735 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
736 			int metadata)
737 {
738 	struct end_io_wq *end_io_wq;
739 	end_io_wq = kmalloc(sizeof(*end_io_wq), GFP_NOFS);
740 	if (!end_io_wq)
741 		return -ENOMEM;
742 
743 	end_io_wq->private = bio->bi_private;
744 	end_io_wq->end_io = bio->bi_end_io;
745 	end_io_wq->info = info;
746 	end_io_wq->error = 0;
747 	end_io_wq->bio = bio;
748 	end_io_wq->metadata = metadata;
749 
750 	bio->bi_private = end_io_wq;
751 	bio->bi_end_io = end_workqueue_bio;
752 	return 0;
753 }
754 
755 unsigned long btrfs_async_submit_limit(struct btrfs_fs_info *info)
756 {
757 	unsigned long limit = min_t(unsigned long,
758 				    info->thread_pool_size,
759 				    info->fs_devices->open_devices);
760 	return 256 * limit;
761 }
762 
763 static void run_one_async_start(struct btrfs_work *work)
764 {
765 	struct async_submit_bio *async;
766 	int ret;
767 
768 	async = container_of(work, struct  async_submit_bio, work);
769 	ret = async->submit_bio_start(async->inode, async->rw, async->bio,
770 				      async->mirror_num, async->bio_flags,
771 				      async->bio_offset);
772 	if (ret)
773 		async->error = ret;
774 }
775 
776 static void run_one_async_done(struct btrfs_work *work)
777 {
778 	struct btrfs_fs_info *fs_info;
779 	struct async_submit_bio *async;
780 	int limit;
781 
782 	async = container_of(work, struct  async_submit_bio, work);
783 	fs_info = BTRFS_I(async->inode)->root->fs_info;
784 
785 	limit = btrfs_async_submit_limit(fs_info);
786 	limit = limit * 2 / 3;
787 
788 	if (atomic_dec_return(&fs_info->nr_async_submits) < limit &&
789 	    waitqueue_active(&fs_info->async_submit_wait))
790 		wake_up(&fs_info->async_submit_wait);
791 
792 	/* If an error occured we just want to clean up the bio and move on */
793 	if (async->error) {
794 		bio_endio(async->bio, async->error);
795 		return;
796 	}
797 
798 	async->submit_bio_done(async->inode, async->rw, async->bio,
799 			       async->mirror_num, async->bio_flags,
800 			       async->bio_offset);
801 }
802 
803 static void run_one_async_free(struct btrfs_work *work)
804 {
805 	struct async_submit_bio *async;
806 
807 	async = container_of(work, struct  async_submit_bio, work);
808 	kfree(async);
809 }
810 
811 int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
812 			int rw, struct bio *bio, int mirror_num,
813 			unsigned long bio_flags,
814 			u64 bio_offset,
815 			extent_submit_bio_hook_t *submit_bio_start,
816 			extent_submit_bio_hook_t *submit_bio_done)
817 {
818 	struct async_submit_bio *async;
819 
820 	async = kmalloc(sizeof(*async), GFP_NOFS);
821 	if (!async)
822 		return -ENOMEM;
823 
824 	async->inode = inode;
825 	async->rw = rw;
826 	async->bio = bio;
827 	async->mirror_num = mirror_num;
828 	async->submit_bio_start = submit_bio_start;
829 	async->submit_bio_done = submit_bio_done;
830 
831 	btrfs_init_work(&async->work, run_one_async_start,
832 			run_one_async_done, run_one_async_free);
833 
834 	async->bio_flags = bio_flags;
835 	async->bio_offset = bio_offset;
836 
837 	async->error = 0;
838 
839 	atomic_inc(&fs_info->nr_async_submits);
840 
841 	if (rw & REQ_SYNC)
842 		btrfs_set_work_high_priority(&async->work);
843 
844 	btrfs_queue_work(fs_info->workers, &async->work);
845 
846 	while (atomic_read(&fs_info->async_submit_draining) &&
847 	      atomic_read(&fs_info->nr_async_submits)) {
848 		wait_event(fs_info->async_submit_wait,
849 			   (atomic_read(&fs_info->nr_async_submits) == 0));
850 	}
851 
852 	return 0;
853 }
854 
855 static int btree_csum_one_bio(struct bio *bio)
856 {
857 	struct bio_vec *bvec;
858 	struct btrfs_root *root;
859 	int i, ret = 0;
860 
861 	bio_for_each_segment_all(bvec, bio, i) {
862 		root = BTRFS_I(bvec->bv_page->mapping->host)->root;
863 		ret = csum_dirty_buffer(root, bvec->bv_page);
864 		if (ret)
865 			break;
866 	}
867 
868 	return ret;
869 }
870 
871 static int __btree_submit_bio_start(struct inode *inode, int rw,
872 				    struct bio *bio, int mirror_num,
873 				    unsigned long bio_flags,
874 				    u64 bio_offset)
875 {
876 	/*
877 	 * when we're called for a write, we're already in the async
878 	 * submission context.  Just jump into btrfs_map_bio
879 	 */
880 	return btree_csum_one_bio(bio);
881 }
882 
883 static int __btree_submit_bio_done(struct inode *inode, int rw, struct bio *bio,
884 				 int mirror_num, unsigned long bio_flags,
885 				 u64 bio_offset)
886 {
887 	int ret;
888 
889 	/*
890 	 * when we're called for a write, we're already in the async
891 	 * submission context.  Just jump into btrfs_map_bio
892 	 */
893 	ret = btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1);
894 	if (ret)
895 		bio_endio(bio, ret);
896 	return ret;
897 }
898 
899 static int check_async_write(struct inode *inode, unsigned long bio_flags)
900 {
901 	if (bio_flags & EXTENT_BIO_TREE_LOG)
902 		return 0;
903 #ifdef CONFIG_X86
904 	if (cpu_has_xmm4_2)
905 		return 0;
906 #endif
907 	return 1;
908 }
909 
910 static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
911 				 int mirror_num, unsigned long bio_flags,
912 				 u64 bio_offset)
913 {
914 	int async = check_async_write(inode, bio_flags);
915 	int ret;
916 
917 	if (!(rw & REQ_WRITE)) {
918 		/*
919 		 * called for a read, do the setup so that checksum validation
920 		 * can happen in the async kernel threads
921 		 */
922 		ret = btrfs_bio_wq_end_io(BTRFS_I(inode)->root->fs_info,
923 					  bio, 1);
924 		if (ret)
925 			goto out_w_error;
926 		ret = btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
927 				    mirror_num, 0);
928 	} else if (!async) {
929 		ret = btree_csum_one_bio(bio);
930 		if (ret)
931 			goto out_w_error;
932 		ret = btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
933 				    mirror_num, 0);
934 	} else {
935 		/*
936 		 * kthread helpers are used to submit writes so that
937 		 * checksumming can happen in parallel across all CPUs
938 		 */
939 		ret = btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
940 					  inode, rw, bio, mirror_num, 0,
941 					  bio_offset,
942 					  __btree_submit_bio_start,
943 					  __btree_submit_bio_done);
944 	}
945 
946 	if (ret) {
947 out_w_error:
948 		bio_endio(bio, ret);
949 	}
950 	return ret;
951 }
952 
953 #ifdef CONFIG_MIGRATION
954 static int btree_migratepage(struct address_space *mapping,
955 			struct page *newpage, struct page *page,
956 			enum migrate_mode mode)
957 {
958 	/*
959 	 * we can't safely write a btree page from here,
960 	 * we haven't done the locking hook
961 	 */
962 	if (PageDirty(page))
963 		return -EAGAIN;
964 	/*
965 	 * Buffers may be managed in a filesystem specific way.
966 	 * We must have no buffers or drop them.
967 	 */
968 	if (page_has_private(page) &&
969 	    !try_to_release_page(page, GFP_KERNEL))
970 		return -EAGAIN;
971 	return migrate_page(mapping, newpage, page, mode);
972 }
973 #endif
974 
975 
976 static int btree_writepages(struct address_space *mapping,
977 			    struct writeback_control *wbc)
978 {
979 	struct btrfs_fs_info *fs_info;
980 	int ret;
981 
982 	if (wbc->sync_mode == WB_SYNC_NONE) {
983 
984 		if (wbc->for_kupdate)
985 			return 0;
986 
987 		fs_info = BTRFS_I(mapping->host)->root->fs_info;
988 		/* this is a bit racy, but that's ok */
989 		ret = percpu_counter_compare(&fs_info->dirty_metadata_bytes,
990 					     BTRFS_DIRTY_METADATA_THRESH);
991 		if (ret < 0)
992 			return 0;
993 	}
994 	return btree_write_cache_pages(mapping, wbc);
995 }
996 
997 static int btree_readpage(struct file *file, struct page *page)
998 {
999 	struct extent_io_tree *tree;
1000 	tree = &BTRFS_I(page->mapping->host)->io_tree;
1001 	return extent_read_full_page(tree, page, btree_get_extent, 0);
1002 }
1003 
1004 static int btree_releasepage(struct page *page, gfp_t gfp_flags)
1005 {
1006 	if (PageWriteback(page) || PageDirty(page))
1007 		return 0;
1008 
1009 	return try_release_extent_buffer(page);
1010 }
1011 
1012 static void btree_invalidatepage(struct page *page, unsigned int offset,
1013 				 unsigned int length)
1014 {
1015 	struct extent_io_tree *tree;
1016 	tree = &BTRFS_I(page->mapping->host)->io_tree;
1017 	extent_invalidatepage(tree, page, offset);
1018 	btree_releasepage(page, GFP_NOFS);
1019 	if (PagePrivate(page)) {
1020 		btrfs_warn(BTRFS_I(page->mapping->host)->root->fs_info,
1021 			   "page private not zero on page %llu",
1022 			   (unsigned long long)page_offset(page));
1023 		ClearPagePrivate(page);
1024 		set_page_private(page, 0);
1025 		page_cache_release(page);
1026 	}
1027 }
1028 
1029 static int btree_set_page_dirty(struct page *page)
1030 {
1031 #ifdef DEBUG
1032 	struct extent_buffer *eb;
1033 
1034 	BUG_ON(!PagePrivate(page));
1035 	eb = (struct extent_buffer *)page->private;
1036 	BUG_ON(!eb);
1037 	BUG_ON(!test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
1038 	BUG_ON(!atomic_read(&eb->refs));
1039 	btrfs_assert_tree_locked(eb);
1040 #endif
1041 	return __set_page_dirty_nobuffers(page);
1042 }
1043 
1044 static const struct address_space_operations btree_aops = {
1045 	.readpage	= btree_readpage,
1046 	.writepages	= btree_writepages,
1047 	.releasepage	= btree_releasepage,
1048 	.invalidatepage = btree_invalidatepage,
1049 #ifdef CONFIG_MIGRATION
1050 	.migratepage	= btree_migratepage,
1051 #endif
1052 	.set_page_dirty = btree_set_page_dirty,
1053 };
1054 
1055 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
1056 			 u64 parent_transid)
1057 {
1058 	struct extent_buffer *buf = NULL;
1059 	struct inode *btree_inode = root->fs_info->btree_inode;
1060 	int ret = 0;
1061 
1062 	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
1063 	if (!buf)
1064 		return 0;
1065 	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
1066 				 buf, 0, WAIT_NONE, btree_get_extent, 0);
1067 	free_extent_buffer(buf);
1068 	return ret;
1069 }
1070 
1071 int reada_tree_block_flagged(struct btrfs_root *root, u64 bytenr, u32 blocksize,
1072 			 int mirror_num, struct extent_buffer **eb)
1073 {
1074 	struct extent_buffer *buf = NULL;
1075 	struct inode *btree_inode = root->fs_info->btree_inode;
1076 	struct extent_io_tree *io_tree = &BTRFS_I(btree_inode)->io_tree;
1077 	int ret;
1078 
1079 	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
1080 	if (!buf)
1081 		return 0;
1082 
1083 	set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags);
1084 
1085 	ret = read_extent_buffer_pages(io_tree, buf, 0, WAIT_PAGE_LOCK,
1086 				       btree_get_extent, mirror_num);
1087 	if (ret) {
1088 		free_extent_buffer(buf);
1089 		return ret;
1090 	}
1091 
1092 	if (test_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags)) {
1093 		free_extent_buffer(buf);
1094 		return -EIO;
1095 	} else if (extent_buffer_uptodate(buf)) {
1096 		*eb = buf;
1097 	} else {
1098 		free_extent_buffer(buf);
1099 	}
1100 	return 0;
1101 }
1102 
1103 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
1104 					    u64 bytenr, u32 blocksize)
1105 {
1106 	return find_extent_buffer(root->fs_info, bytenr);
1107 }
1108 
1109 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
1110 						 u64 bytenr, u32 blocksize)
1111 {
1112 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1113 	if (unlikely(test_bit(BTRFS_ROOT_DUMMY_ROOT, &root->state)))
1114 		return alloc_test_extent_buffer(root->fs_info, bytenr,
1115 						blocksize);
1116 #endif
1117 	return alloc_extent_buffer(root->fs_info, bytenr, blocksize);
1118 }
1119 
1120 
1121 int btrfs_write_tree_block(struct extent_buffer *buf)
1122 {
1123 	return filemap_fdatawrite_range(buf->pages[0]->mapping, buf->start,
1124 					buf->start + buf->len - 1);
1125 }
1126 
1127 int btrfs_wait_tree_block_writeback(struct extent_buffer *buf)
1128 {
1129 	return filemap_fdatawait_range(buf->pages[0]->mapping,
1130 				       buf->start, buf->start + buf->len - 1);
1131 }
1132 
1133 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
1134 				      u32 blocksize, u64 parent_transid)
1135 {
1136 	struct extent_buffer *buf = NULL;
1137 	int ret;
1138 
1139 	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
1140 	if (!buf)
1141 		return NULL;
1142 
1143 	ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
1144 	if (ret) {
1145 		free_extent_buffer(buf);
1146 		return NULL;
1147 	}
1148 	return buf;
1149 
1150 }
1151 
1152 void clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1153 		      struct extent_buffer *buf)
1154 {
1155 	struct btrfs_fs_info *fs_info = root->fs_info;
1156 
1157 	if (btrfs_header_generation(buf) ==
1158 	    fs_info->running_transaction->transid) {
1159 		btrfs_assert_tree_locked(buf);
1160 
1161 		if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &buf->bflags)) {
1162 			__percpu_counter_add(&fs_info->dirty_metadata_bytes,
1163 					     -buf->len,
1164 					     fs_info->dirty_metadata_batch);
1165 			/* ugh, clear_extent_buffer_dirty needs to lock the page */
1166 			btrfs_set_lock_blocking(buf);
1167 			clear_extent_buffer_dirty(buf);
1168 		}
1169 	}
1170 }
1171 
1172 static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)
1173 {
1174 	struct btrfs_subvolume_writers *writers;
1175 	int ret;
1176 
1177 	writers = kmalloc(sizeof(*writers), GFP_NOFS);
1178 	if (!writers)
1179 		return ERR_PTR(-ENOMEM);
1180 
1181 	ret = percpu_counter_init(&writers->counter, 0);
1182 	if (ret < 0) {
1183 		kfree(writers);
1184 		return ERR_PTR(ret);
1185 	}
1186 
1187 	init_waitqueue_head(&writers->wait);
1188 	return writers;
1189 }
1190 
1191 static void
1192 btrfs_free_subvolume_writers(struct btrfs_subvolume_writers *writers)
1193 {
1194 	percpu_counter_destroy(&writers->counter);
1195 	kfree(writers);
1196 }
1197 
1198 static void __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
1199 			 u32 stripesize, struct btrfs_root *root,
1200 			 struct btrfs_fs_info *fs_info,
1201 			 u64 objectid)
1202 {
1203 	root->node = NULL;
1204 	root->commit_root = NULL;
1205 	root->sectorsize = sectorsize;
1206 	root->nodesize = nodesize;
1207 	root->leafsize = leafsize;
1208 	root->stripesize = stripesize;
1209 	root->state = 0;
1210 	root->orphan_cleanup_state = 0;
1211 
1212 	root->objectid = objectid;
1213 	root->last_trans = 0;
1214 	root->highest_objectid = 0;
1215 	root->nr_delalloc_inodes = 0;
1216 	root->nr_ordered_extents = 0;
1217 	root->name = NULL;
1218 	root->inode_tree = RB_ROOT;
1219 	INIT_RADIX_TREE(&root->delayed_nodes_tree, GFP_ATOMIC);
1220 	root->block_rsv = NULL;
1221 	root->orphan_block_rsv = NULL;
1222 
1223 	INIT_LIST_HEAD(&root->dirty_list);
1224 	INIT_LIST_HEAD(&root->root_list);
1225 	INIT_LIST_HEAD(&root->delalloc_inodes);
1226 	INIT_LIST_HEAD(&root->delalloc_root);
1227 	INIT_LIST_HEAD(&root->ordered_extents);
1228 	INIT_LIST_HEAD(&root->ordered_root);
1229 	INIT_LIST_HEAD(&root->logged_list[0]);
1230 	INIT_LIST_HEAD(&root->logged_list[1]);
1231 	spin_lock_init(&root->orphan_lock);
1232 	spin_lock_init(&root->inode_lock);
1233 	spin_lock_init(&root->delalloc_lock);
1234 	spin_lock_init(&root->ordered_extent_lock);
1235 	spin_lock_init(&root->accounting_lock);
1236 	spin_lock_init(&root->log_extents_lock[0]);
1237 	spin_lock_init(&root->log_extents_lock[1]);
1238 	mutex_init(&root->objectid_mutex);
1239 	mutex_init(&root->log_mutex);
1240 	mutex_init(&root->ordered_extent_mutex);
1241 	mutex_init(&root->delalloc_mutex);
1242 	init_waitqueue_head(&root->log_writer_wait);
1243 	init_waitqueue_head(&root->log_commit_wait[0]);
1244 	init_waitqueue_head(&root->log_commit_wait[1]);
1245 	INIT_LIST_HEAD(&root->log_ctxs[0]);
1246 	INIT_LIST_HEAD(&root->log_ctxs[1]);
1247 	atomic_set(&root->log_commit[0], 0);
1248 	atomic_set(&root->log_commit[1], 0);
1249 	atomic_set(&root->log_writers, 0);
1250 	atomic_set(&root->log_batch, 0);
1251 	atomic_set(&root->orphan_inodes, 0);
1252 	atomic_set(&root->refs, 1);
1253 	atomic_set(&root->will_be_snapshoted, 0);
1254 	root->log_transid = 0;
1255 	root->log_transid_committed = -1;
1256 	root->last_log_commit = 0;
1257 	if (fs_info)
1258 		extent_io_tree_init(&root->dirty_log_pages,
1259 				     fs_info->btree_inode->i_mapping);
1260 
1261 	memset(&root->root_key, 0, sizeof(root->root_key));
1262 	memset(&root->root_item, 0, sizeof(root->root_item));
1263 	memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
1264 	memset(&root->root_kobj, 0, sizeof(root->root_kobj));
1265 	if (fs_info)
1266 		root->defrag_trans_start = fs_info->generation;
1267 	else
1268 		root->defrag_trans_start = 0;
1269 	init_completion(&root->kobj_unregister);
1270 	root->root_key.objectid = objectid;
1271 	root->anon_dev = 0;
1272 
1273 	spin_lock_init(&root->root_item_lock);
1274 }
1275 
1276 static struct btrfs_root *btrfs_alloc_root(struct btrfs_fs_info *fs_info)
1277 {
1278 	struct btrfs_root *root = kzalloc(sizeof(*root), GFP_NOFS);
1279 	if (root)
1280 		root->fs_info = fs_info;
1281 	return root;
1282 }
1283 
1284 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
1285 /* Should only be used by the testing infrastructure */
1286 struct btrfs_root *btrfs_alloc_dummy_root(void)
1287 {
1288 	struct btrfs_root *root;
1289 
1290 	root = btrfs_alloc_root(NULL);
1291 	if (!root)
1292 		return ERR_PTR(-ENOMEM);
1293 	__setup_root(4096, 4096, 4096, 4096, root, NULL, 1);
1294 	set_bit(BTRFS_ROOT_DUMMY_ROOT, &root->state);
1295 	root->alloc_bytenr = 0;
1296 
1297 	return root;
1298 }
1299 #endif
1300 
1301 struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
1302 				     struct btrfs_fs_info *fs_info,
1303 				     u64 objectid)
1304 {
1305 	struct extent_buffer *leaf;
1306 	struct btrfs_root *tree_root = fs_info->tree_root;
1307 	struct btrfs_root *root;
1308 	struct btrfs_key key;
1309 	int ret = 0;
1310 	uuid_le uuid;
1311 
1312 	root = btrfs_alloc_root(fs_info);
1313 	if (!root)
1314 		return ERR_PTR(-ENOMEM);
1315 
1316 	__setup_root(tree_root->nodesize, tree_root->leafsize,
1317 		     tree_root->sectorsize, tree_root->stripesize,
1318 		     root, fs_info, objectid);
1319 	root->root_key.objectid = objectid;
1320 	root->root_key.type = BTRFS_ROOT_ITEM_KEY;
1321 	root->root_key.offset = 0;
1322 
1323 	leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
1324 				      0, objectid, NULL, 0, 0, 0);
1325 	if (IS_ERR(leaf)) {
1326 		ret = PTR_ERR(leaf);
1327 		leaf = NULL;
1328 		goto fail;
1329 	}
1330 
1331 	memset_extent_buffer(leaf, 0, 0, sizeof(struct btrfs_header));
1332 	btrfs_set_header_bytenr(leaf, leaf->start);
1333 	btrfs_set_header_generation(leaf, trans->transid);
1334 	btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
1335 	btrfs_set_header_owner(leaf, objectid);
1336 	root->node = leaf;
1337 
1338 	write_extent_buffer(leaf, fs_info->fsid, btrfs_header_fsid(),
1339 			    BTRFS_FSID_SIZE);
1340 	write_extent_buffer(leaf, fs_info->chunk_tree_uuid,
1341 			    btrfs_header_chunk_tree_uuid(leaf),
1342 			    BTRFS_UUID_SIZE);
1343 	btrfs_mark_buffer_dirty(leaf);
1344 
1345 	root->commit_root = btrfs_root_node(root);
1346 	set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
1347 
1348 	root->root_item.flags = 0;
1349 	root->root_item.byte_limit = 0;
1350 	btrfs_set_root_bytenr(&root->root_item, leaf->start);
1351 	btrfs_set_root_generation(&root->root_item, trans->transid);
1352 	btrfs_set_root_level(&root->root_item, 0);
1353 	btrfs_set_root_refs(&root->root_item, 1);
1354 	btrfs_set_root_used(&root->root_item, leaf->len);
1355 	btrfs_set_root_last_snapshot(&root->root_item, 0);
1356 	btrfs_set_root_dirid(&root->root_item, 0);
1357 	uuid_le_gen(&uuid);
1358 	memcpy(root->root_item.uuid, uuid.b, BTRFS_UUID_SIZE);
1359 	root->root_item.drop_level = 0;
1360 
1361 	key.objectid = objectid;
1362 	key.type = BTRFS_ROOT_ITEM_KEY;
1363 	key.offset = 0;
1364 	ret = btrfs_insert_root(trans, tree_root, &key, &root->root_item);
1365 	if (ret)
1366 		goto fail;
1367 
1368 	btrfs_tree_unlock(leaf);
1369 
1370 	return root;
1371 
1372 fail:
1373 	if (leaf) {
1374 		btrfs_tree_unlock(leaf);
1375 		free_extent_buffer(root->commit_root);
1376 		free_extent_buffer(leaf);
1377 	}
1378 	kfree(root);
1379 
1380 	return ERR_PTR(ret);
1381 }
1382 
1383 static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,
1384 					 struct btrfs_fs_info *fs_info)
1385 {
1386 	struct btrfs_root *root;
1387 	struct btrfs_root *tree_root = fs_info->tree_root;
1388 	struct extent_buffer *leaf;
1389 
1390 	root = btrfs_alloc_root(fs_info);
1391 	if (!root)
1392 		return ERR_PTR(-ENOMEM);
1393 
1394 	__setup_root(tree_root->nodesize, tree_root->leafsize,
1395 		     tree_root->sectorsize, tree_root->stripesize,
1396 		     root, fs_info, BTRFS_TREE_LOG_OBJECTID);
1397 
1398 	root->root_key.objectid = BTRFS_TREE_LOG_OBJECTID;
1399 	root->root_key.type = BTRFS_ROOT_ITEM_KEY;
1400 	root->root_key.offset = BTRFS_TREE_LOG_OBJECTID;
1401 
1402 	/*
1403 	 * DON'T set REF_COWS for log trees
1404 	 *
1405 	 * log trees do not get reference counted because they go away
1406 	 * before a real commit is actually done.  They do store pointers
1407 	 * to file data extents, and those reference counts still get
1408 	 * updated (along with back refs to the log tree).
1409 	 */
1410 
1411 	leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
1412 				      BTRFS_TREE_LOG_OBJECTID, NULL,
1413 				      0, 0, 0);
1414 	if (IS_ERR(leaf)) {
1415 		kfree(root);
1416 		return ERR_CAST(leaf);
1417 	}
1418 
1419 	memset_extent_buffer(leaf, 0, 0, sizeof(struct btrfs_header));
1420 	btrfs_set_header_bytenr(leaf, leaf->start);
1421 	btrfs_set_header_generation(leaf, trans->transid);
1422 	btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
1423 	btrfs_set_header_owner(leaf, BTRFS_TREE_LOG_OBJECTID);
1424 	root->node = leaf;
1425 
1426 	write_extent_buffer(root->node, root->fs_info->fsid,
1427 			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
1428 	btrfs_mark_buffer_dirty(root->node);
1429 	btrfs_tree_unlock(root->node);
1430 	return root;
1431 }
1432 
1433 int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
1434 			     struct btrfs_fs_info *fs_info)
1435 {
1436 	struct btrfs_root *log_root;
1437 
1438 	log_root = alloc_log_tree(trans, fs_info);
1439 	if (IS_ERR(log_root))
1440 		return PTR_ERR(log_root);
1441 	WARN_ON(fs_info->log_root_tree);
1442 	fs_info->log_root_tree = log_root;
1443 	return 0;
1444 }
1445 
1446 int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
1447 		       struct btrfs_root *root)
1448 {
1449 	struct btrfs_root *log_root;
1450 	struct btrfs_inode_item *inode_item;
1451 
1452 	log_root = alloc_log_tree(trans, root->fs_info);
1453 	if (IS_ERR(log_root))
1454 		return PTR_ERR(log_root);
1455 
1456 	log_root->last_trans = trans->transid;
1457 	log_root->root_key.offset = root->root_key.objectid;
1458 
1459 	inode_item = &log_root->root_item.inode;
1460 	btrfs_set_stack_inode_generation(inode_item, 1);
1461 	btrfs_set_stack_inode_size(inode_item, 3);
1462 	btrfs_set_stack_inode_nlink(inode_item, 1);
1463 	btrfs_set_stack_inode_nbytes(inode_item, root->leafsize);
1464 	btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
1465 
1466 	btrfs_set_root_node(&log_root->root_item, log_root->node);
1467 
1468 	WARN_ON(root->log_root);
1469 	root->log_root = log_root;
1470 	root->log_transid = 0;
1471 	root->log_transid_committed = -1;
1472 	root->last_log_commit = 0;
1473 	return 0;
1474 }
1475 
1476 static struct btrfs_root *btrfs_read_tree_root(struct btrfs_root *tree_root,
1477 					       struct btrfs_key *key)
1478 {
1479 	struct btrfs_root *root;
1480 	struct btrfs_fs_info *fs_info = tree_root->fs_info;
1481 	struct btrfs_path *path;
1482 	u64 generation;
1483 	u32 blocksize;
1484 	int ret;
1485 
1486 	path = btrfs_alloc_path();
1487 	if (!path)
1488 		return ERR_PTR(-ENOMEM);
1489 
1490 	root = btrfs_alloc_root(fs_info);
1491 	if (!root) {
1492 		ret = -ENOMEM;
1493 		goto alloc_fail;
1494 	}
1495 
1496 	__setup_root(tree_root->nodesize, tree_root->leafsize,
1497 		     tree_root->sectorsize, tree_root->stripesize,
1498 		     root, fs_info, key->objectid);
1499 
1500 	ret = btrfs_find_root(tree_root, key, path,
1501 			      &root->root_item, &root->root_key);
1502 	if (ret) {
1503 		if (ret > 0)
1504 			ret = -ENOENT;
1505 		goto find_fail;
1506 	}
1507 
1508 	generation = btrfs_root_generation(&root->root_item);
1509 	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
1510 	root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
1511 				     blocksize, generation);
1512 	if (!root->node) {
1513 		ret = -ENOMEM;
1514 		goto find_fail;
1515 	} else if (!btrfs_buffer_uptodate(root->node, generation, 0)) {
1516 		ret = -EIO;
1517 		goto read_fail;
1518 	}
1519 	root->commit_root = btrfs_root_node(root);
1520 out:
1521 	btrfs_free_path(path);
1522 	return root;
1523 
1524 read_fail:
1525 	free_extent_buffer(root->node);
1526 find_fail:
1527 	kfree(root);
1528 alloc_fail:
1529 	root = ERR_PTR(ret);
1530 	goto out;
1531 }
1532 
1533 struct btrfs_root *btrfs_read_fs_root(struct btrfs_root *tree_root,
1534 				      struct btrfs_key *location)
1535 {
1536 	struct btrfs_root *root;
1537 
1538 	root = btrfs_read_tree_root(tree_root, location);
1539 	if (IS_ERR(root))
1540 		return root;
1541 
1542 	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
1543 		set_bit(BTRFS_ROOT_REF_COWS, &root->state);
1544 		btrfs_check_and_init_root_item(&root->root_item);
1545 	}
1546 
1547 	return root;
1548 }
1549 
1550 int btrfs_init_fs_root(struct btrfs_root *root)
1551 {
1552 	int ret;
1553 	struct btrfs_subvolume_writers *writers;
1554 
1555 	root->free_ino_ctl = kzalloc(sizeof(*root->free_ino_ctl), GFP_NOFS);
1556 	root->free_ino_pinned = kzalloc(sizeof(*root->free_ino_pinned),
1557 					GFP_NOFS);
1558 	if (!root->free_ino_pinned || !root->free_ino_ctl) {
1559 		ret = -ENOMEM;
1560 		goto fail;
1561 	}
1562 
1563 	writers = btrfs_alloc_subvolume_writers();
1564 	if (IS_ERR(writers)) {
1565 		ret = PTR_ERR(writers);
1566 		goto fail;
1567 	}
1568 	root->subv_writers = writers;
1569 
1570 	btrfs_init_free_ino_ctl(root);
1571 	spin_lock_init(&root->cache_lock);
1572 	init_waitqueue_head(&root->cache_wait);
1573 
1574 	ret = get_anon_bdev(&root->anon_dev);
1575 	if (ret)
1576 		goto free_writers;
1577 	return 0;
1578 
1579 free_writers:
1580 	btrfs_free_subvolume_writers(root->subv_writers);
1581 fail:
1582 	kfree(root->free_ino_ctl);
1583 	kfree(root->free_ino_pinned);
1584 	return ret;
1585 }
1586 
1587 static struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
1588 					       u64 root_id)
1589 {
1590 	struct btrfs_root *root;
1591 
1592 	spin_lock(&fs_info->fs_roots_radix_lock);
1593 	root = radix_tree_lookup(&fs_info->fs_roots_radix,
1594 				 (unsigned long)root_id);
1595 	spin_unlock(&fs_info->fs_roots_radix_lock);
1596 	return root;
1597 }
1598 
1599 int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
1600 			 struct btrfs_root *root)
1601 {
1602 	int ret;
1603 
1604 	ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
1605 	if (ret)
1606 		return ret;
1607 
1608 	spin_lock(&fs_info->fs_roots_radix_lock);
1609 	ret = radix_tree_insert(&fs_info->fs_roots_radix,
1610 				(unsigned long)root->root_key.objectid,
1611 				root);
1612 	if (ret == 0)
1613 		set_bit(BTRFS_ROOT_IN_RADIX, &root->state);
1614 	spin_unlock(&fs_info->fs_roots_radix_lock);
1615 	radix_tree_preload_end();
1616 
1617 	return ret;
1618 }
1619 
1620 struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
1621 				     struct btrfs_key *location,
1622 				     bool check_ref)
1623 {
1624 	struct btrfs_root *root;
1625 	int ret;
1626 
1627 	if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
1628 		return fs_info->tree_root;
1629 	if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
1630 		return fs_info->extent_root;
1631 	if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
1632 		return fs_info->chunk_root;
1633 	if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
1634 		return fs_info->dev_root;
1635 	if (location->objectid == BTRFS_CSUM_TREE_OBJECTID)
1636 		return fs_info->csum_root;
1637 	if (location->objectid == BTRFS_QUOTA_TREE_OBJECTID)
1638 		return fs_info->quota_root ? fs_info->quota_root :
1639 					     ERR_PTR(-ENOENT);
1640 	if (location->objectid == BTRFS_UUID_TREE_OBJECTID)
1641 		return fs_info->uuid_root ? fs_info->uuid_root :
1642 					    ERR_PTR(-ENOENT);
1643 again:
1644 	root = btrfs_lookup_fs_root(fs_info, location->objectid);
1645 	if (root) {
1646 		if (check_ref && btrfs_root_refs(&root->root_item) == 0)
1647 			return ERR_PTR(-ENOENT);
1648 		return root;
1649 	}
1650 
1651 	root = btrfs_read_fs_root(fs_info->tree_root, location);
1652 	if (IS_ERR(root))
1653 		return root;
1654 
1655 	if (check_ref && btrfs_root_refs(&root->root_item) == 0) {
1656 		ret = -ENOENT;
1657 		goto fail;
1658 	}
1659 
1660 	ret = btrfs_init_fs_root(root);
1661 	if (ret)
1662 		goto fail;
1663 
1664 	ret = btrfs_find_item(fs_info->tree_root, NULL, BTRFS_ORPHAN_OBJECTID,
1665 			location->objectid, BTRFS_ORPHAN_ITEM_KEY, NULL);
1666 	if (ret < 0)
1667 		goto fail;
1668 	if (ret == 0)
1669 		set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
1670 
1671 	ret = btrfs_insert_fs_root(fs_info, root);
1672 	if (ret) {
1673 		if (ret == -EEXIST) {
1674 			free_fs_root(root);
1675 			goto again;
1676 		}
1677 		goto fail;
1678 	}
1679 	return root;
1680 fail:
1681 	free_fs_root(root);
1682 	return ERR_PTR(ret);
1683 }
1684 
1685 static int btrfs_congested_fn(void *congested_data, int bdi_bits)
1686 {
1687 	struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
1688 	int ret = 0;
1689 	struct btrfs_device *device;
1690 	struct backing_dev_info *bdi;
1691 
1692 	rcu_read_lock();
1693 	list_for_each_entry_rcu(device, &info->fs_devices->devices, dev_list) {
1694 		if (!device->bdev)
1695 			continue;
1696 		bdi = blk_get_backing_dev_info(device->bdev);
1697 		if (bdi && bdi_congested(bdi, bdi_bits)) {
1698 			ret = 1;
1699 			break;
1700 		}
1701 	}
1702 	rcu_read_unlock();
1703 	return ret;
1704 }
1705 
1706 /*
1707  * If this fails, caller must call bdi_destroy() to get rid of the
1708  * bdi again.
1709  */
1710 static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
1711 {
1712 	int err;
1713 
1714 	bdi->capabilities = BDI_CAP_MAP_COPY;
1715 	err = bdi_setup_and_register(bdi, "btrfs", BDI_CAP_MAP_COPY);
1716 	if (err)
1717 		return err;
1718 
1719 	bdi->ra_pages	= default_backing_dev_info.ra_pages;
1720 	bdi->congested_fn	= btrfs_congested_fn;
1721 	bdi->congested_data	= info;
1722 	return 0;
1723 }
1724 
1725 /*
1726  * called by the kthread helper functions to finally call the bio end_io
1727  * functions.  This is where read checksum verification actually happens
1728  */
1729 static void end_workqueue_fn(struct btrfs_work *work)
1730 {
1731 	struct bio *bio;
1732 	struct end_io_wq *end_io_wq;
1733 	int error;
1734 
1735 	end_io_wq = container_of(work, struct end_io_wq, work);
1736 	bio = end_io_wq->bio;
1737 
1738 	error = end_io_wq->error;
1739 	bio->bi_private = end_io_wq->private;
1740 	bio->bi_end_io = end_io_wq->end_io;
1741 	kfree(end_io_wq);
1742 	bio_endio_nodec(bio, error);
1743 }
1744 
1745 static int cleaner_kthread(void *arg)
1746 {
1747 	struct btrfs_root *root = arg;
1748 	int again;
1749 
1750 	do {
1751 		again = 0;
1752 
1753 		/* Make the cleaner go to sleep early. */
1754 		if (btrfs_need_cleaner_sleep(root))
1755 			goto sleep;
1756 
1757 		if (!mutex_trylock(&root->fs_info->cleaner_mutex))
1758 			goto sleep;
1759 
1760 		/*
1761 		 * Avoid the problem that we change the status of the fs
1762 		 * during the above check and trylock.
1763 		 */
1764 		if (btrfs_need_cleaner_sleep(root)) {
1765 			mutex_unlock(&root->fs_info->cleaner_mutex);
1766 			goto sleep;
1767 		}
1768 
1769 		btrfs_run_delayed_iputs(root);
1770 		again = btrfs_clean_one_deleted_snapshot(root);
1771 		mutex_unlock(&root->fs_info->cleaner_mutex);
1772 
1773 		/*
1774 		 * The defragger has dealt with the R/O remount and umount,
1775 		 * needn't do anything special here.
1776 		 */
1777 		btrfs_run_defrag_inodes(root->fs_info);
1778 sleep:
1779 		if (!try_to_freeze() && !again) {
1780 			set_current_state(TASK_INTERRUPTIBLE);
1781 			if (!kthread_should_stop())
1782 				schedule();
1783 			__set_current_state(TASK_RUNNING);
1784 		}
1785 	} while (!kthread_should_stop());
1786 	return 0;
1787 }
1788 
1789 static int transaction_kthread(void *arg)
1790 {
1791 	struct btrfs_root *root = arg;
1792 	struct btrfs_trans_handle *trans;
1793 	struct btrfs_transaction *cur;
1794 	u64 transid;
1795 	unsigned long now;
1796 	unsigned long delay;
1797 	bool cannot_commit;
1798 
1799 	do {
1800 		cannot_commit = false;
1801 		delay = HZ * root->fs_info->commit_interval;
1802 		mutex_lock(&root->fs_info->transaction_kthread_mutex);
1803 
1804 		spin_lock(&root->fs_info->trans_lock);
1805 		cur = root->fs_info->running_transaction;
1806 		if (!cur) {
1807 			spin_unlock(&root->fs_info->trans_lock);
1808 			goto sleep;
1809 		}
1810 
1811 		now = get_seconds();
1812 		if (cur->state < TRANS_STATE_BLOCKED &&
1813 		    (now < cur->start_time ||
1814 		     now - cur->start_time < root->fs_info->commit_interval)) {
1815 			spin_unlock(&root->fs_info->trans_lock);
1816 			delay = HZ * 5;
1817 			goto sleep;
1818 		}
1819 		transid = cur->transid;
1820 		spin_unlock(&root->fs_info->trans_lock);
1821 
1822 		/* If the file system is aborted, this will always fail. */
1823 		trans = btrfs_attach_transaction(root);
1824 		if (IS_ERR(trans)) {
1825 			if (PTR_ERR(trans) != -ENOENT)
1826 				cannot_commit = true;
1827 			goto sleep;
1828 		}
1829 		if (transid == trans->transid) {
1830 			btrfs_commit_transaction(trans, root);
1831 		} else {
1832 			btrfs_end_transaction(trans, root);
1833 		}
1834 sleep:
1835 		wake_up_process(root->fs_info->cleaner_kthread);
1836 		mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1837 
1838 		if (unlikely(test_bit(BTRFS_FS_STATE_ERROR,
1839 				      &root->fs_info->fs_state)))
1840 			btrfs_cleanup_transaction(root);
1841 		if (!try_to_freeze()) {
1842 			set_current_state(TASK_INTERRUPTIBLE);
1843 			if (!kthread_should_stop() &&
1844 			    (!btrfs_transaction_blocked(root->fs_info) ||
1845 			     cannot_commit))
1846 				schedule_timeout(delay);
1847 			__set_current_state(TASK_RUNNING);
1848 		}
1849 	} while (!kthread_should_stop());
1850 	return 0;
1851 }
1852 
1853 /*
1854  * this will find the highest generation in the array of
1855  * root backups.  The index of the highest array is returned,
1856  * or -1 if we can't find anything.
1857  *
1858  * We check to make sure the array is valid by comparing the
1859  * generation of the latest  root in the array with the generation
1860  * in the super block.  If they don't match we pitch it.
1861  */
1862 static int find_newest_super_backup(struct btrfs_fs_info *info, u64 newest_gen)
1863 {
1864 	u64 cur;
1865 	int newest_index = -1;
1866 	struct btrfs_root_backup *root_backup;
1867 	int i;
1868 
1869 	for (i = 0; i < BTRFS_NUM_BACKUP_ROOTS; i++) {
1870 		root_backup = info->super_copy->super_roots + i;
1871 		cur = btrfs_backup_tree_root_gen(root_backup);
1872 		if (cur == newest_gen)
1873 			newest_index = i;
1874 	}
1875 
1876 	/* check to see if we actually wrapped around */
1877 	if (newest_index == BTRFS_NUM_BACKUP_ROOTS - 1) {
1878 		root_backup = info->super_copy->super_roots;
1879 		cur = btrfs_backup_tree_root_gen(root_backup);
1880 		if (cur == newest_gen)
1881 			newest_index = 0;
1882 	}
1883 	return newest_index;
1884 }
1885 
1886 
1887 /*
1888  * find the oldest backup so we know where to store new entries
1889  * in the backup array.  This will set the backup_root_index
1890  * field in the fs_info struct
1891  */
1892 static void find_oldest_super_backup(struct btrfs_fs_info *info,
1893 				     u64 newest_gen)
1894 {
1895 	int newest_index = -1;
1896 
1897 	newest_index = find_newest_super_backup(info, newest_gen);
1898 	/* if there was garbage in there, just move along */
1899 	if (newest_index == -1) {
1900 		info->backup_root_index = 0;
1901 	} else {
1902 		info->backup_root_index = (newest_index + 1) % BTRFS_NUM_BACKUP_ROOTS;
1903 	}
1904 }
1905 
1906 /*
1907  * copy all the root pointers into the super backup array.
1908  * this will bump the backup pointer by one when it is
1909  * done
1910  */
1911 static void backup_super_roots(struct btrfs_fs_info *info)
1912 {
1913 	int next_backup;
1914 	struct btrfs_root_backup *root_backup;
1915 	int last_backup;
1916 
1917 	next_backup = info->backup_root_index;
1918 	last_backup = (next_backup + BTRFS_NUM_BACKUP_ROOTS - 1) %
1919 		BTRFS_NUM_BACKUP_ROOTS;
1920 
1921 	/*
1922 	 * just overwrite the last backup if we're at the same generation
1923 	 * this happens only at umount
1924 	 */
1925 	root_backup = info->super_for_commit->super_roots + last_backup;
1926 	if (btrfs_backup_tree_root_gen(root_backup) ==
1927 	    btrfs_header_generation(info->tree_root->node))
1928 		next_backup = last_backup;
1929 
1930 	root_backup = info->super_for_commit->super_roots + next_backup;
1931 
1932 	/*
1933 	 * make sure all of our padding and empty slots get zero filled
1934 	 * regardless of which ones we use today
1935 	 */
1936 	memset(root_backup, 0, sizeof(*root_backup));
1937 
1938 	info->backup_root_index = (next_backup + 1) % BTRFS_NUM_BACKUP_ROOTS;
1939 
1940 	btrfs_set_backup_tree_root(root_backup, info->tree_root->node->start);
1941 	btrfs_set_backup_tree_root_gen(root_backup,
1942 			       btrfs_header_generation(info->tree_root->node));
1943 
1944 	btrfs_set_backup_tree_root_level(root_backup,
1945 			       btrfs_header_level(info->tree_root->node));
1946 
1947 	btrfs_set_backup_chunk_root(root_backup, info->chunk_root->node->start);
1948 	btrfs_set_backup_chunk_root_gen(root_backup,
1949 			       btrfs_header_generation(info->chunk_root->node));
1950 	btrfs_set_backup_chunk_root_level(root_backup,
1951 			       btrfs_header_level(info->chunk_root->node));
1952 
1953 	btrfs_set_backup_extent_root(root_backup, info->extent_root->node->start);
1954 	btrfs_set_backup_extent_root_gen(root_backup,
1955 			       btrfs_header_generation(info->extent_root->node));
1956 	btrfs_set_backup_extent_root_level(root_backup,
1957 			       btrfs_header_level(info->extent_root->node));
1958 
1959 	/*
1960 	 * we might commit during log recovery, which happens before we set
1961 	 * the fs_root.  Make sure it is valid before we fill it in.
1962 	 */
1963 	if (info->fs_root && info->fs_root->node) {
1964 		btrfs_set_backup_fs_root(root_backup,
1965 					 info->fs_root->node->start);
1966 		btrfs_set_backup_fs_root_gen(root_backup,
1967 			       btrfs_header_generation(info->fs_root->node));
1968 		btrfs_set_backup_fs_root_level(root_backup,
1969 			       btrfs_header_level(info->fs_root->node));
1970 	}
1971 
1972 	btrfs_set_backup_dev_root(root_backup, info->dev_root->node->start);
1973 	btrfs_set_backup_dev_root_gen(root_backup,
1974 			       btrfs_header_generation(info->dev_root->node));
1975 	btrfs_set_backup_dev_root_level(root_backup,
1976 				       btrfs_header_level(info->dev_root->node));
1977 
1978 	btrfs_set_backup_csum_root(root_backup, info->csum_root->node->start);
1979 	btrfs_set_backup_csum_root_gen(root_backup,
1980 			       btrfs_header_generation(info->csum_root->node));
1981 	btrfs_set_backup_csum_root_level(root_backup,
1982 			       btrfs_header_level(info->csum_root->node));
1983 
1984 	btrfs_set_backup_total_bytes(root_backup,
1985 			     btrfs_super_total_bytes(info->super_copy));
1986 	btrfs_set_backup_bytes_used(root_backup,
1987 			     btrfs_super_bytes_used(info->super_copy));
1988 	btrfs_set_backup_num_devices(root_backup,
1989 			     btrfs_super_num_devices(info->super_copy));
1990 
1991 	/*
1992 	 * if we don't copy this out to the super_copy, it won't get remembered
1993 	 * for the next commit
1994 	 */
1995 	memcpy(&info->super_copy->super_roots,
1996 	       &info->super_for_commit->super_roots,
1997 	       sizeof(*root_backup) * BTRFS_NUM_BACKUP_ROOTS);
1998 }
1999 
2000 /*
2001  * this copies info out of the root backup array and back into
2002  * the in-memory super block.  It is meant to help iterate through
2003  * the array, so you send it the number of backups you've already
2004  * tried and the last backup index you used.
2005  *
2006  * this returns -1 when it has tried all the backups
2007  */
2008 static noinline int next_root_backup(struct btrfs_fs_info *info,
2009 				     struct btrfs_super_block *super,
2010 				     int *num_backups_tried, int *backup_index)
2011 {
2012 	struct btrfs_root_backup *root_backup;
2013 	int newest = *backup_index;
2014 
2015 	if (*num_backups_tried == 0) {
2016 		u64 gen = btrfs_super_generation(super);
2017 
2018 		newest = find_newest_super_backup(info, gen);
2019 		if (newest == -1)
2020 			return -1;
2021 
2022 		*backup_index = newest;
2023 		*num_backups_tried = 1;
2024 	} else if (*num_backups_tried == BTRFS_NUM_BACKUP_ROOTS) {
2025 		/* we've tried all the backups, all done */
2026 		return -1;
2027 	} else {
2028 		/* jump to the next oldest backup */
2029 		newest = (*backup_index + BTRFS_NUM_BACKUP_ROOTS - 1) %
2030 			BTRFS_NUM_BACKUP_ROOTS;
2031 		*backup_index = newest;
2032 		*num_backups_tried += 1;
2033 	}
2034 	root_backup = super->super_roots + newest;
2035 
2036 	btrfs_set_super_generation(super,
2037 				   btrfs_backup_tree_root_gen(root_backup));
2038 	btrfs_set_super_root(super, btrfs_backup_tree_root(root_backup));
2039 	btrfs_set_super_root_level(super,
2040 				   btrfs_backup_tree_root_level(root_backup));
2041 	btrfs_set_super_bytes_used(super, btrfs_backup_bytes_used(root_backup));
2042 
2043 	/*
2044 	 * fixme: the total bytes and num_devices need to match or we should
2045 	 * need a fsck
2046 	 */
2047 	btrfs_set_super_total_bytes(super, btrfs_backup_total_bytes(root_backup));
2048 	btrfs_set_super_num_devices(super, btrfs_backup_num_devices(root_backup));
2049 	return 0;
2050 }
2051 
2052 /* helper to cleanup workers */
2053 static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
2054 {
2055 	btrfs_destroy_workqueue(fs_info->fixup_workers);
2056 	btrfs_destroy_workqueue(fs_info->delalloc_workers);
2057 	btrfs_destroy_workqueue(fs_info->workers);
2058 	btrfs_destroy_workqueue(fs_info->endio_workers);
2059 	btrfs_destroy_workqueue(fs_info->endio_meta_workers);
2060 	btrfs_destroy_workqueue(fs_info->endio_raid56_workers);
2061 	btrfs_destroy_workqueue(fs_info->rmw_workers);
2062 	btrfs_destroy_workqueue(fs_info->endio_meta_write_workers);
2063 	btrfs_destroy_workqueue(fs_info->endio_write_workers);
2064 	btrfs_destroy_workqueue(fs_info->endio_freespace_worker);
2065 	btrfs_destroy_workqueue(fs_info->submit_workers);
2066 	btrfs_destroy_workqueue(fs_info->delayed_workers);
2067 	btrfs_destroy_workqueue(fs_info->caching_workers);
2068 	btrfs_destroy_workqueue(fs_info->readahead_workers);
2069 	btrfs_destroy_workqueue(fs_info->flush_workers);
2070 	btrfs_destroy_workqueue(fs_info->qgroup_rescan_workers);
2071 	btrfs_destroy_workqueue(fs_info->extent_workers);
2072 }
2073 
2074 static void free_root_extent_buffers(struct btrfs_root *root)
2075 {
2076 	if (root) {
2077 		free_extent_buffer(root->node);
2078 		free_extent_buffer(root->commit_root);
2079 		root->node = NULL;
2080 		root->commit_root = NULL;
2081 	}
2082 }
2083 
2084 /* helper to cleanup tree roots */
2085 static void free_root_pointers(struct btrfs_fs_info *info, int chunk_root)
2086 {
2087 	free_root_extent_buffers(info->tree_root);
2088 
2089 	free_root_extent_buffers(info->dev_root);
2090 	free_root_extent_buffers(info->extent_root);
2091 	free_root_extent_buffers(info->csum_root);
2092 	free_root_extent_buffers(info->quota_root);
2093 	free_root_extent_buffers(info->uuid_root);
2094 	if (chunk_root)
2095 		free_root_extent_buffers(info->chunk_root);
2096 }
2097 
2098 void btrfs_free_fs_roots(struct btrfs_fs_info *fs_info)
2099 {
2100 	int ret;
2101 	struct btrfs_root *gang[8];
2102 	int i;
2103 
2104 	while (!list_empty(&fs_info->dead_roots)) {
2105 		gang[0] = list_entry(fs_info->dead_roots.next,
2106 				     struct btrfs_root, root_list);
2107 		list_del(&gang[0]->root_list);
2108 
2109 		if (test_bit(BTRFS_ROOT_IN_RADIX, &gang[0]->state)) {
2110 			btrfs_drop_and_free_fs_root(fs_info, gang[0]);
2111 		} else {
2112 			free_extent_buffer(gang[0]->node);
2113 			free_extent_buffer(gang[0]->commit_root);
2114 			btrfs_put_fs_root(gang[0]);
2115 		}
2116 	}
2117 
2118 	while (1) {
2119 		ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
2120 					     (void **)gang, 0,
2121 					     ARRAY_SIZE(gang));
2122 		if (!ret)
2123 			break;
2124 		for (i = 0; i < ret; i++)
2125 			btrfs_drop_and_free_fs_root(fs_info, gang[i]);
2126 	}
2127 
2128 	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
2129 		btrfs_free_log_root_tree(NULL, fs_info);
2130 		btrfs_destroy_pinned_extent(fs_info->tree_root,
2131 					    fs_info->pinned_extents);
2132 	}
2133 }
2134 
2135 int open_ctree(struct super_block *sb,
2136 	       struct btrfs_fs_devices *fs_devices,
2137 	       char *options)
2138 {
2139 	u32 sectorsize;
2140 	u32 nodesize;
2141 	u32 leafsize;
2142 	u32 blocksize;
2143 	u32 stripesize;
2144 	u64 generation;
2145 	u64 features;
2146 	struct btrfs_key location;
2147 	struct buffer_head *bh;
2148 	struct btrfs_super_block *disk_super;
2149 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2150 	struct btrfs_root *tree_root;
2151 	struct btrfs_root *extent_root;
2152 	struct btrfs_root *csum_root;
2153 	struct btrfs_root *chunk_root;
2154 	struct btrfs_root *dev_root;
2155 	struct btrfs_root *quota_root;
2156 	struct btrfs_root *uuid_root;
2157 	struct btrfs_root *log_tree_root;
2158 	int ret;
2159 	int err = -EINVAL;
2160 	int num_backups_tried = 0;
2161 	int backup_index = 0;
2162 	int max_active;
2163 	int flags = WQ_MEM_RECLAIM | WQ_FREEZABLE | WQ_UNBOUND;
2164 	bool create_uuid_tree;
2165 	bool check_uuid_tree;
2166 
2167 	tree_root = fs_info->tree_root = btrfs_alloc_root(fs_info);
2168 	chunk_root = fs_info->chunk_root = btrfs_alloc_root(fs_info);
2169 	if (!tree_root || !chunk_root) {
2170 		err = -ENOMEM;
2171 		goto fail;
2172 	}
2173 
2174 	ret = init_srcu_struct(&fs_info->subvol_srcu);
2175 	if (ret) {
2176 		err = ret;
2177 		goto fail;
2178 	}
2179 
2180 	ret = setup_bdi(fs_info, &fs_info->bdi);
2181 	if (ret) {
2182 		err = ret;
2183 		goto fail_srcu;
2184 	}
2185 
2186 	ret = percpu_counter_init(&fs_info->dirty_metadata_bytes, 0);
2187 	if (ret) {
2188 		err = ret;
2189 		goto fail_bdi;
2190 	}
2191 	fs_info->dirty_metadata_batch = PAGE_CACHE_SIZE *
2192 					(1 + ilog2(nr_cpu_ids));
2193 
2194 	ret = percpu_counter_init(&fs_info->delalloc_bytes, 0);
2195 	if (ret) {
2196 		err = ret;
2197 		goto fail_dirty_metadata_bytes;
2198 	}
2199 
2200 	ret = percpu_counter_init(&fs_info->bio_counter, 0);
2201 	if (ret) {
2202 		err = ret;
2203 		goto fail_delalloc_bytes;
2204 	}
2205 
2206 	fs_info->btree_inode = new_inode(sb);
2207 	if (!fs_info->btree_inode) {
2208 		err = -ENOMEM;
2209 		goto fail_bio_counter;
2210 	}
2211 
2212 	mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
2213 
2214 	INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC);
2215 	INIT_RADIX_TREE(&fs_info->buffer_radix, GFP_ATOMIC);
2216 	INIT_LIST_HEAD(&fs_info->trans_list);
2217 	INIT_LIST_HEAD(&fs_info->dead_roots);
2218 	INIT_LIST_HEAD(&fs_info->delayed_iputs);
2219 	INIT_LIST_HEAD(&fs_info->delalloc_roots);
2220 	INIT_LIST_HEAD(&fs_info->caching_block_groups);
2221 	spin_lock_init(&fs_info->delalloc_root_lock);
2222 	spin_lock_init(&fs_info->trans_lock);
2223 	spin_lock_init(&fs_info->fs_roots_radix_lock);
2224 	spin_lock_init(&fs_info->delayed_iput_lock);
2225 	spin_lock_init(&fs_info->defrag_inodes_lock);
2226 	spin_lock_init(&fs_info->free_chunk_lock);
2227 	spin_lock_init(&fs_info->tree_mod_seq_lock);
2228 	spin_lock_init(&fs_info->super_lock);
2229 	spin_lock_init(&fs_info->qgroup_op_lock);
2230 	spin_lock_init(&fs_info->buffer_lock);
2231 	rwlock_init(&fs_info->tree_mod_log_lock);
2232 	mutex_init(&fs_info->reloc_mutex);
2233 	mutex_init(&fs_info->delalloc_root_mutex);
2234 	seqlock_init(&fs_info->profiles_lock);
2235 
2236 	init_completion(&fs_info->kobj_unregister);
2237 	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
2238 	INIT_LIST_HEAD(&fs_info->space_info);
2239 	INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);
2240 	btrfs_mapping_init(&fs_info->mapping_tree);
2241 	btrfs_init_block_rsv(&fs_info->global_block_rsv,
2242 			     BTRFS_BLOCK_RSV_GLOBAL);
2243 	btrfs_init_block_rsv(&fs_info->delalloc_block_rsv,
2244 			     BTRFS_BLOCK_RSV_DELALLOC);
2245 	btrfs_init_block_rsv(&fs_info->trans_block_rsv, BTRFS_BLOCK_RSV_TRANS);
2246 	btrfs_init_block_rsv(&fs_info->chunk_block_rsv, BTRFS_BLOCK_RSV_CHUNK);
2247 	btrfs_init_block_rsv(&fs_info->empty_block_rsv, BTRFS_BLOCK_RSV_EMPTY);
2248 	btrfs_init_block_rsv(&fs_info->delayed_block_rsv,
2249 			     BTRFS_BLOCK_RSV_DELOPS);
2250 	atomic_set(&fs_info->nr_async_submits, 0);
2251 	atomic_set(&fs_info->async_delalloc_pages, 0);
2252 	atomic_set(&fs_info->async_submit_draining, 0);
2253 	atomic_set(&fs_info->nr_async_bios, 0);
2254 	atomic_set(&fs_info->defrag_running, 0);
2255 	atomic_set(&fs_info->qgroup_op_seq, 0);
2256 	atomic64_set(&fs_info->tree_mod_seq, 0);
2257 	fs_info->sb = sb;
2258 	fs_info->max_inline = 8192 * 1024;
2259 	fs_info->metadata_ratio = 0;
2260 	fs_info->defrag_inodes = RB_ROOT;
2261 	fs_info->free_chunk_space = 0;
2262 	fs_info->tree_mod_log = RB_ROOT;
2263 	fs_info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
2264 	fs_info->avg_delayed_ref_runtime = div64_u64(NSEC_PER_SEC, 64);
2265 	/* readahead state */
2266 	INIT_RADIX_TREE(&fs_info->reada_tree, GFP_NOFS & ~__GFP_WAIT);
2267 	spin_lock_init(&fs_info->reada_lock);
2268 
2269 	fs_info->thread_pool_size = min_t(unsigned long,
2270 					  num_online_cpus() + 2, 8);
2271 
2272 	INIT_LIST_HEAD(&fs_info->ordered_roots);
2273 	spin_lock_init(&fs_info->ordered_root_lock);
2274 	fs_info->delayed_root = kmalloc(sizeof(struct btrfs_delayed_root),
2275 					GFP_NOFS);
2276 	if (!fs_info->delayed_root) {
2277 		err = -ENOMEM;
2278 		goto fail_iput;
2279 	}
2280 	btrfs_init_delayed_root(fs_info->delayed_root);
2281 
2282 	mutex_init(&fs_info->scrub_lock);
2283 	atomic_set(&fs_info->scrubs_running, 0);
2284 	atomic_set(&fs_info->scrub_pause_req, 0);
2285 	atomic_set(&fs_info->scrubs_paused, 0);
2286 	atomic_set(&fs_info->scrub_cancel_req, 0);
2287 	init_waitqueue_head(&fs_info->replace_wait);
2288 	init_waitqueue_head(&fs_info->scrub_pause_wait);
2289 	fs_info->scrub_workers_refcnt = 0;
2290 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2291 	fs_info->check_integrity_print_mask = 0;
2292 #endif
2293 
2294 	spin_lock_init(&fs_info->balance_lock);
2295 	mutex_init(&fs_info->balance_mutex);
2296 	atomic_set(&fs_info->balance_running, 0);
2297 	atomic_set(&fs_info->balance_pause_req, 0);
2298 	atomic_set(&fs_info->balance_cancel_req, 0);
2299 	fs_info->balance_ctl = NULL;
2300 	init_waitqueue_head(&fs_info->balance_wait_q);
2301 	btrfs_init_async_reclaim_work(&fs_info->async_reclaim_work);
2302 
2303 	sb->s_blocksize = 4096;
2304 	sb->s_blocksize_bits = blksize_bits(4096);
2305 	sb->s_bdi = &fs_info->bdi;
2306 
2307 	fs_info->btree_inode->i_ino = BTRFS_BTREE_INODE_OBJECTID;
2308 	set_nlink(fs_info->btree_inode, 1);
2309 	/*
2310 	 * we set the i_size on the btree inode to the max possible int.
2311 	 * the real end of the address space is determined by all of
2312 	 * the devices in the system
2313 	 */
2314 	fs_info->btree_inode->i_size = OFFSET_MAX;
2315 	fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
2316 	fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
2317 
2318 	RB_CLEAR_NODE(&BTRFS_I(fs_info->btree_inode)->rb_node);
2319 	extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
2320 			     fs_info->btree_inode->i_mapping);
2321 	BTRFS_I(fs_info->btree_inode)->io_tree.track_uptodate = 0;
2322 	extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree);
2323 
2324 	BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
2325 
2326 	BTRFS_I(fs_info->btree_inode)->root = tree_root;
2327 	memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
2328 	       sizeof(struct btrfs_key));
2329 	set_bit(BTRFS_INODE_DUMMY,
2330 		&BTRFS_I(fs_info->btree_inode)->runtime_flags);
2331 	btrfs_insert_inode_hash(fs_info->btree_inode);
2332 
2333 	spin_lock_init(&fs_info->block_group_cache_lock);
2334 	fs_info->block_group_cache_tree = RB_ROOT;
2335 	fs_info->first_logical_byte = (u64)-1;
2336 
2337 	extent_io_tree_init(&fs_info->freed_extents[0],
2338 			     fs_info->btree_inode->i_mapping);
2339 	extent_io_tree_init(&fs_info->freed_extents[1],
2340 			     fs_info->btree_inode->i_mapping);
2341 	fs_info->pinned_extents = &fs_info->freed_extents[0];
2342 	fs_info->do_barriers = 1;
2343 
2344 
2345 	mutex_init(&fs_info->ordered_operations_mutex);
2346 	mutex_init(&fs_info->ordered_extent_flush_mutex);
2347 	mutex_init(&fs_info->tree_log_mutex);
2348 	mutex_init(&fs_info->chunk_mutex);
2349 	mutex_init(&fs_info->transaction_kthread_mutex);
2350 	mutex_init(&fs_info->cleaner_mutex);
2351 	mutex_init(&fs_info->volume_mutex);
2352 	init_rwsem(&fs_info->commit_root_sem);
2353 	init_rwsem(&fs_info->cleanup_work_sem);
2354 	init_rwsem(&fs_info->subvol_sem);
2355 	sema_init(&fs_info->uuid_tree_rescan_sem, 1);
2356 	fs_info->dev_replace.lock_owner = 0;
2357 	atomic_set(&fs_info->dev_replace.nesting_level, 0);
2358 	mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount);
2359 	mutex_init(&fs_info->dev_replace.lock_management_lock);
2360 	mutex_init(&fs_info->dev_replace.lock);
2361 
2362 	spin_lock_init(&fs_info->qgroup_lock);
2363 	mutex_init(&fs_info->qgroup_ioctl_lock);
2364 	fs_info->qgroup_tree = RB_ROOT;
2365 	fs_info->qgroup_op_tree = RB_ROOT;
2366 	INIT_LIST_HEAD(&fs_info->dirty_qgroups);
2367 	fs_info->qgroup_seq = 1;
2368 	fs_info->quota_enabled = 0;
2369 	fs_info->pending_quota_state = 0;
2370 	fs_info->qgroup_ulist = NULL;
2371 	mutex_init(&fs_info->qgroup_rescan_lock);
2372 
2373 	btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
2374 	btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
2375 
2376 	init_waitqueue_head(&fs_info->transaction_throttle);
2377 	init_waitqueue_head(&fs_info->transaction_wait);
2378 	init_waitqueue_head(&fs_info->transaction_blocked_wait);
2379 	init_waitqueue_head(&fs_info->async_submit_wait);
2380 
2381 	ret = btrfs_alloc_stripe_hash_table(fs_info);
2382 	if (ret) {
2383 		err = ret;
2384 		goto fail_alloc;
2385 	}
2386 
2387 	__setup_root(4096, 4096, 4096, 4096, tree_root,
2388 		     fs_info, BTRFS_ROOT_TREE_OBJECTID);
2389 
2390 	invalidate_bdev(fs_devices->latest_bdev);
2391 
2392 	/*
2393 	 * Read super block and check the signature bytes only
2394 	 */
2395 	bh = btrfs_read_dev_super(fs_devices->latest_bdev);
2396 	if (!bh) {
2397 		err = -EINVAL;
2398 		goto fail_alloc;
2399 	}
2400 
2401 	/*
2402 	 * We want to check superblock checksum, the type is stored inside.
2403 	 * Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k).
2404 	 */
2405 	if (btrfs_check_super_csum(bh->b_data)) {
2406 		printk(KERN_ERR "BTRFS: superblock checksum mismatch\n");
2407 		err = -EINVAL;
2408 		goto fail_alloc;
2409 	}
2410 
2411 	/*
2412 	 * super_copy is zeroed at allocation time and we never touch the
2413 	 * following bytes up to INFO_SIZE, the checksum is calculated from
2414 	 * the whole block of INFO_SIZE
2415 	 */
2416 	memcpy(fs_info->super_copy, bh->b_data, sizeof(*fs_info->super_copy));
2417 	memcpy(fs_info->super_for_commit, fs_info->super_copy,
2418 	       sizeof(*fs_info->super_for_commit));
2419 	brelse(bh);
2420 
2421 	memcpy(fs_info->fsid, fs_info->super_copy->fsid, BTRFS_FSID_SIZE);
2422 
2423 	ret = btrfs_check_super_valid(fs_info, sb->s_flags & MS_RDONLY);
2424 	if (ret) {
2425 		printk(KERN_ERR "BTRFS: superblock contains fatal errors\n");
2426 		err = -EINVAL;
2427 		goto fail_alloc;
2428 	}
2429 
2430 	disk_super = fs_info->super_copy;
2431 	if (!btrfs_super_root(disk_super))
2432 		goto fail_alloc;
2433 
2434 	/* check FS state, whether FS is broken. */
2435 	if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_ERROR)
2436 		set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
2437 
2438 	/*
2439 	 * run through our array of backup supers and setup
2440 	 * our ring pointer to the oldest one
2441 	 */
2442 	generation = btrfs_super_generation(disk_super);
2443 	find_oldest_super_backup(fs_info, generation);
2444 
2445 	/*
2446 	 * In the long term, we'll store the compression type in the super
2447 	 * block, and it'll be used for per file compression control.
2448 	 */
2449 	fs_info->compress_type = BTRFS_COMPRESS_ZLIB;
2450 
2451 	ret = btrfs_parse_options(tree_root, options);
2452 	if (ret) {
2453 		err = ret;
2454 		goto fail_alloc;
2455 	}
2456 
2457 	features = btrfs_super_incompat_flags(disk_super) &
2458 		~BTRFS_FEATURE_INCOMPAT_SUPP;
2459 	if (features) {
2460 		printk(KERN_ERR "BTRFS: couldn't mount because of "
2461 		       "unsupported optional features (%Lx).\n",
2462 		       features);
2463 		err = -EINVAL;
2464 		goto fail_alloc;
2465 	}
2466 
2467 	if (btrfs_super_leafsize(disk_super) !=
2468 	    btrfs_super_nodesize(disk_super)) {
2469 		printk(KERN_ERR "BTRFS: couldn't mount because metadata "
2470 		       "blocksizes don't match.  node %d leaf %d\n",
2471 		       btrfs_super_nodesize(disk_super),
2472 		       btrfs_super_leafsize(disk_super));
2473 		err = -EINVAL;
2474 		goto fail_alloc;
2475 	}
2476 	if (btrfs_super_leafsize(disk_super) > BTRFS_MAX_METADATA_BLOCKSIZE) {
2477 		printk(KERN_ERR "BTRFS: couldn't mount because metadata "
2478 		       "blocksize (%d) was too large\n",
2479 		       btrfs_super_leafsize(disk_super));
2480 		err = -EINVAL;
2481 		goto fail_alloc;
2482 	}
2483 
2484 	features = btrfs_super_incompat_flags(disk_super);
2485 	features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
2486 	if (tree_root->fs_info->compress_type == BTRFS_COMPRESS_LZO)
2487 		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
2488 
2489 	if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
2490 		printk(KERN_ERR "BTRFS: has skinny extents\n");
2491 
2492 	/*
2493 	 * flag our filesystem as having big metadata blocks if
2494 	 * they are bigger than the page size
2495 	 */
2496 	if (btrfs_super_leafsize(disk_super) > PAGE_CACHE_SIZE) {
2497 		if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
2498 			printk(KERN_INFO "BTRFS: flagging fs with big metadata feature\n");
2499 		features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
2500 	}
2501 
2502 	nodesize = btrfs_super_nodesize(disk_super);
2503 	leafsize = btrfs_super_leafsize(disk_super);
2504 	sectorsize = btrfs_super_sectorsize(disk_super);
2505 	stripesize = btrfs_super_stripesize(disk_super);
2506 	fs_info->dirty_metadata_batch = leafsize * (1 + ilog2(nr_cpu_ids));
2507 	fs_info->delalloc_batch = sectorsize * 512 * (1 + ilog2(nr_cpu_ids));
2508 
2509 	/*
2510 	 * mixed block groups end up with duplicate but slightly offset
2511 	 * extent buffers for the same range.  It leads to corruptions
2512 	 */
2513 	if ((features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS) &&
2514 	    (sectorsize != leafsize)) {
2515 		printk(KERN_WARNING "BTRFS: unequal leaf/node/sector sizes "
2516 				"are not allowed for mixed block groups on %s\n",
2517 				sb->s_id);
2518 		goto fail_alloc;
2519 	}
2520 
2521 	/*
2522 	 * Needn't use the lock because there is no other task which will
2523 	 * update the flag.
2524 	 */
2525 	btrfs_set_super_incompat_flags(disk_super, features);
2526 
2527 	features = btrfs_super_compat_ro_flags(disk_super) &
2528 		~BTRFS_FEATURE_COMPAT_RO_SUPP;
2529 	if (!(sb->s_flags & MS_RDONLY) && features) {
2530 		printk(KERN_ERR "BTRFS: couldn't mount RDWR because of "
2531 		       "unsupported option features (%Lx).\n",
2532 		       features);
2533 		err = -EINVAL;
2534 		goto fail_alloc;
2535 	}
2536 
2537 	max_active = fs_info->thread_pool_size;
2538 
2539 	fs_info->workers =
2540 		btrfs_alloc_workqueue("worker", flags | WQ_HIGHPRI,
2541 				      max_active, 16);
2542 
2543 	fs_info->delalloc_workers =
2544 		btrfs_alloc_workqueue("delalloc", flags, max_active, 2);
2545 
2546 	fs_info->flush_workers =
2547 		btrfs_alloc_workqueue("flush_delalloc", flags, max_active, 0);
2548 
2549 	fs_info->caching_workers =
2550 		btrfs_alloc_workqueue("cache", flags, max_active, 0);
2551 
2552 	/*
2553 	 * a higher idle thresh on the submit workers makes it much more
2554 	 * likely that bios will be send down in a sane order to the
2555 	 * devices
2556 	 */
2557 	fs_info->submit_workers =
2558 		btrfs_alloc_workqueue("submit", flags,
2559 				      min_t(u64, fs_devices->num_devices,
2560 					    max_active), 64);
2561 
2562 	fs_info->fixup_workers =
2563 		btrfs_alloc_workqueue("fixup", flags, 1, 0);
2564 
2565 	/*
2566 	 * endios are largely parallel and should have a very
2567 	 * low idle thresh
2568 	 */
2569 	fs_info->endio_workers =
2570 		btrfs_alloc_workqueue("endio", flags, max_active, 4);
2571 	fs_info->endio_meta_workers =
2572 		btrfs_alloc_workqueue("endio-meta", flags, max_active, 4);
2573 	fs_info->endio_meta_write_workers =
2574 		btrfs_alloc_workqueue("endio-meta-write", flags, max_active, 2);
2575 	fs_info->endio_raid56_workers =
2576 		btrfs_alloc_workqueue("endio-raid56", flags, max_active, 4);
2577 	fs_info->rmw_workers =
2578 		btrfs_alloc_workqueue("rmw", flags, max_active, 2);
2579 	fs_info->endio_write_workers =
2580 		btrfs_alloc_workqueue("endio-write", flags, max_active, 2);
2581 	fs_info->endio_freespace_worker =
2582 		btrfs_alloc_workqueue("freespace-write", flags, max_active, 0);
2583 	fs_info->delayed_workers =
2584 		btrfs_alloc_workqueue("delayed-meta", flags, max_active, 0);
2585 	fs_info->readahead_workers =
2586 		btrfs_alloc_workqueue("readahead", flags, max_active, 2);
2587 	fs_info->qgroup_rescan_workers =
2588 		btrfs_alloc_workqueue("qgroup-rescan", flags, 1, 0);
2589 	fs_info->extent_workers =
2590 		btrfs_alloc_workqueue("extent-refs", flags,
2591 				      min_t(u64, fs_devices->num_devices,
2592 					    max_active), 8);
2593 
2594 	if (!(fs_info->workers && fs_info->delalloc_workers &&
2595 	      fs_info->submit_workers && fs_info->flush_workers &&
2596 	      fs_info->endio_workers && fs_info->endio_meta_workers &&
2597 	      fs_info->endio_meta_write_workers &&
2598 	      fs_info->endio_write_workers && fs_info->endio_raid56_workers &&
2599 	      fs_info->endio_freespace_worker && fs_info->rmw_workers &&
2600 	      fs_info->caching_workers && fs_info->readahead_workers &&
2601 	      fs_info->fixup_workers && fs_info->delayed_workers &&
2602 	      fs_info->fixup_workers && fs_info->extent_workers &&
2603 	      fs_info->qgroup_rescan_workers)) {
2604 		err = -ENOMEM;
2605 		goto fail_sb_buffer;
2606 	}
2607 
2608 	fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
2609 	fs_info->bdi.ra_pages = max(fs_info->bdi.ra_pages,
2610 				    4 * 1024 * 1024 / PAGE_CACHE_SIZE);
2611 
2612 	tree_root->nodesize = nodesize;
2613 	tree_root->leafsize = leafsize;
2614 	tree_root->sectorsize = sectorsize;
2615 	tree_root->stripesize = stripesize;
2616 
2617 	sb->s_blocksize = sectorsize;
2618 	sb->s_blocksize_bits = blksize_bits(sectorsize);
2619 
2620 	if (btrfs_super_magic(disk_super) != BTRFS_MAGIC) {
2621 		printk(KERN_INFO "BTRFS: valid FS not found on %s\n", sb->s_id);
2622 		goto fail_sb_buffer;
2623 	}
2624 
2625 	if (sectorsize != PAGE_SIZE) {
2626 		printk(KERN_WARNING "BTRFS: Incompatible sector size(%lu) "
2627 		       "found on %s\n", (unsigned long)sectorsize, sb->s_id);
2628 		goto fail_sb_buffer;
2629 	}
2630 
2631 	mutex_lock(&fs_info->chunk_mutex);
2632 	ret = btrfs_read_sys_array(tree_root);
2633 	mutex_unlock(&fs_info->chunk_mutex);
2634 	if (ret) {
2635 		printk(KERN_WARNING "BTRFS: failed to read the system "
2636 		       "array on %s\n", sb->s_id);
2637 		goto fail_sb_buffer;
2638 	}
2639 
2640 	blocksize = btrfs_level_size(tree_root,
2641 				     btrfs_super_chunk_root_level(disk_super));
2642 	generation = btrfs_super_chunk_root_generation(disk_super);
2643 
2644 	__setup_root(nodesize, leafsize, sectorsize, stripesize,
2645 		     chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
2646 
2647 	chunk_root->node = read_tree_block(chunk_root,
2648 					   btrfs_super_chunk_root(disk_super),
2649 					   blocksize, generation);
2650 	if (!chunk_root->node ||
2651 	    !test_bit(EXTENT_BUFFER_UPTODATE, &chunk_root->node->bflags)) {
2652 		printk(KERN_WARNING "BTRFS: failed to read chunk root on %s\n",
2653 		       sb->s_id);
2654 		goto fail_tree_roots;
2655 	}
2656 	btrfs_set_root_node(&chunk_root->root_item, chunk_root->node);
2657 	chunk_root->commit_root = btrfs_root_node(chunk_root);
2658 
2659 	read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
2660 	   btrfs_header_chunk_tree_uuid(chunk_root->node), BTRFS_UUID_SIZE);
2661 
2662 	ret = btrfs_read_chunk_tree(chunk_root);
2663 	if (ret) {
2664 		printk(KERN_WARNING "BTRFS: failed to read chunk tree on %s\n",
2665 		       sb->s_id);
2666 		goto fail_tree_roots;
2667 	}
2668 
2669 	/*
2670 	 * keep the device that is marked to be the target device for the
2671 	 * dev_replace procedure
2672 	 */
2673 	btrfs_close_extra_devices(fs_info, fs_devices, 0);
2674 
2675 	if (!fs_devices->latest_bdev) {
2676 		printk(KERN_CRIT "BTRFS: failed to read devices on %s\n",
2677 		       sb->s_id);
2678 		goto fail_tree_roots;
2679 	}
2680 
2681 retry_root_backup:
2682 	blocksize = btrfs_level_size(tree_root,
2683 				     btrfs_super_root_level(disk_super));
2684 	generation = btrfs_super_generation(disk_super);
2685 
2686 	tree_root->node = read_tree_block(tree_root,
2687 					  btrfs_super_root(disk_super),
2688 					  blocksize, generation);
2689 	if (!tree_root->node ||
2690 	    !test_bit(EXTENT_BUFFER_UPTODATE, &tree_root->node->bflags)) {
2691 		printk(KERN_WARNING "BTRFS: failed to read tree root on %s\n",
2692 		       sb->s_id);
2693 
2694 		goto recovery_tree_root;
2695 	}
2696 
2697 	btrfs_set_root_node(&tree_root->root_item, tree_root->node);
2698 	tree_root->commit_root = btrfs_root_node(tree_root);
2699 	btrfs_set_root_refs(&tree_root->root_item, 1);
2700 
2701 	location.objectid = BTRFS_EXTENT_TREE_OBJECTID;
2702 	location.type = BTRFS_ROOT_ITEM_KEY;
2703 	location.offset = 0;
2704 
2705 	extent_root = btrfs_read_tree_root(tree_root, &location);
2706 	if (IS_ERR(extent_root)) {
2707 		ret = PTR_ERR(extent_root);
2708 		goto recovery_tree_root;
2709 	}
2710 	set_bit(BTRFS_ROOT_TRACK_DIRTY, &extent_root->state);
2711 	fs_info->extent_root = extent_root;
2712 
2713 	location.objectid = BTRFS_DEV_TREE_OBJECTID;
2714 	dev_root = btrfs_read_tree_root(tree_root, &location);
2715 	if (IS_ERR(dev_root)) {
2716 		ret = PTR_ERR(dev_root);
2717 		goto recovery_tree_root;
2718 	}
2719 	set_bit(BTRFS_ROOT_TRACK_DIRTY, &dev_root->state);
2720 	fs_info->dev_root = dev_root;
2721 	btrfs_init_devices_late(fs_info);
2722 
2723 	location.objectid = BTRFS_CSUM_TREE_OBJECTID;
2724 	csum_root = btrfs_read_tree_root(tree_root, &location);
2725 	if (IS_ERR(csum_root)) {
2726 		ret = PTR_ERR(csum_root);
2727 		goto recovery_tree_root;
2728 	}
2729 	set_bit(BTRFS_ROOT_TRACK_DIRTY, &csum_root->state);
2730 	fs_info->csum_root = csum_root;
2731 
2732 	location.objectid = BTRFS_QUOTA_TREE_OBJECTID;
2733 	quota_root = btrfs_read_tree_root(tree_root, &location);
2734 	if (!IS_ERR(quota_root)) {
2735 		set_bit(BTRFS_ROOT_TRACK_DIRTY, &quota_root->state);
2736 		fs_info->quota_enabled = 1;
2737 		fs_info->pending_quota_state = 1;
2738 		fs_info->quota_root = quota_root;
2739 	}
2740 
2741 	location.objectid = BTRFS_UUID_TREE_OBJECTID;
2742 	uuid_root = btrfs_read_tree_root(tree_root, &location);
2743 	if (IS_ERR(uuid_root)) {
2744 		ret = PTR_ERR(uuid_root);
2745 		if (ret != -ENOENT)
2746 			goto recovery_tree_root;
2747 		create_uuid_tree = true;
2748 		check_uuid_tree = false;
2749 	} else {
2750 		set_bit(BTRFS_ROOT_TRACK_DIRTY, &uuid_root->state);
2751 		fs_info->uuid_root = uuid_root;
2752 		create_uuid_tree = false;
2753 		check_uuid_tree =
2754 		    generation != btrfs_super_uuid_tree_generation(disk_super);
2755 	}
2756 
2757 	fs_info->generation = generation;
2758 	fs_info->last_trans_committed = generation;
2759 
2760 	ret = btrfs_recover_balance(fs_info);
2761 	if (ret) {
2762 		printk(KERN_WARNING "BTRFS: failed to recover balance\n");
2763 		goto fail_block_groups;
2764 	}
2765 
2766 	ret = btrfs_init_dev_stats(fs_info);
2767 	if (ret) {
2768 		printk(KERN_ERR "BTRFS: failed to init dev_stats: %d\n",
2769 		       ret);
2770 		goto fail_block_groups;
2771 	}
2772 
2773 	ret = btrfs_init_dev_replace(fs_info);
2774 	if (ret) {
2775 		pr_err("BTRFS: failed to init dev_replace: %d\n", ret);
2776 		goto fail_block_groups;
2777 	}
2778 
2779 	btrfs_close_extra_devices(fs_info, fs_devices, 1);
2780 
2781 	ret = btrfs_sysfs_add_one(fs_info);
2782 	if (ret) {
2783 		pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
2784 		goto fail_block_groups;
2785 	}
2786 
2787 	ret = btrfs_init_space_info(fs_info);
2788 	if (ret) {
2789 		printk(KERN_ERR "BTRFS: Failed to initial space info: %d\n", ret);
2790 		goto fail_sysfs;
2791 	}
2792 
2793 	ret = btrfs_read_block_groups(extent_root);
2794 	if (ret) {
2795 		printk(KERN_ERR "BTRFS: Failed to read block groups: %d\n", ret);
2796 		goto fail_sysfs;
2797 	}
2798 	fs_info->num_tolerated_disk_barrier_failures =
2799 		btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
2800 	if (fs_info->fs_devices->missing_devices >
2801 	     fs_info->num_tolerated_disk_barrier_failures &&
2802 	    !(sb->s_flags & MS_RDONLY)) {
2803 		printk(KERN_WARNING "BTRFS: "
2804 			"too many missing devices, writeable mount is not allowed\n");
2805 		goto fail_sysfs;
2806 	}
2807 
2808 	fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
2809 					       "btrfs-cleaner");
2810 	if (IS_ERR(fs_info->cleaner_kthread))
2811 		goto fail_sysfs;
2812 
2813 	fs_info->transaction_kthread = kthread_run(transaction_kthread,
2814 						   tree_root,
2815 						   "btrfs-transaction");
2816 	if (IS_ERR(fs_info->transaction_kthread))
2817 		goto fail_cleaner;
2818 
2819 	if (!btrfs_test_opt(tree_root, SSD) &&
2820 	    !btrfs_test_opt(tree_root, NOSSD) &&
2821 	    !fs_info->fs_devices->rotating) {
2822 		printk(KERN_INFO "BTRFS: detected SSD devices, enabling SSD "
2823 		       "mode\n");
2824 		btrfs_set_opt(fs_info->mount_opt, SSD);
2825 	}
2826 
2827 	/* Set the real inode map cache flag */
2828 	if (btrfs_test_opt(tree_root, CHANGE_INODE_CACHE))
2829 		btrfs_set_opt(tree_root->fs_info->mount_opt, INODE_MAP_CACHE);
2830 
2831 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2832 	if (btrfs_test_opt(tree_root, CHECK_INTEGRITY)) {
2833 		ret = btrfsic_mount(tree_root, fs_devices,
2834 				    btrfs_test_opt(tree_root,
2835 					CHECK_INTEGRITY_INCLUDING_EXTENT_DATA) ?
2836 				    1 : 0,
2837 				    fs_info->check_integrity_print_mask);
2838 		if (ret)
2839 			printk(KERN_WARNING "BTRFS: failed to initialize"
2840 			       " integrity check module %s\n", sb->s_id);
2841 	}
2842 #endif
2843 	ret = btrfs_read_qgroup_config(fs_info);
2844 	if (ret)
2845 		goto fail_trans_kthread;
2846 
2847 	/* do not make disk changes in broken FS */
2848 	if (btrfs_super_log_root(disk_super) != 0) {
2849 		u64 bytenr = btrfs_super_log_root(disk_super);
2850 
2851 		if (fs_devices->rw_devices == 0) {
2852 			printk(KERN_WARNING "BTRFS: log replay required "
2853 			       "on RO media\n");
2854 			err = -EIO;
2855 			goto fail_qgroup;
2856 		}
2857 		blocksize =
2858 		     btrfs_level_size(tree_root,
2859 				      btrfs_super_log_root_level(disk_super));
2860 
2861 		log_tree_root = btrfs_alloc_root(fs_info);
2862 		if (!log_tree_root) {
2863 			err = -ENOMEM;
2864 			goto fail_qgroup;
2865 		}
2866 
2867 		__setup_root(nodesize, leafsize, sectorsize, stripesize,
2868 			     log_tree_root, fs_info, BTRFS_TREE_LOG_OBJECTID);
2869 
2870 		log_tree_root->node = read_tree_block(tree_root, bytenr,
2871 						      blocksize,
2872 						      generation + 1);
2873 		if (!log_tree_root->node ||
2874 		    !extent_buffer_uptodate(log_tree_root->node)) {
2875 			printk(KERN_ERR "BTRFS: failed to read log tree\n");
2876 			free_extent_buffer(log_tree_root->node);
2877 			kfree(log_tree_root);
2878 			goto fail_qgroup;
2879 		}
2880 		/* returns with log_tree_root freed on success */
2881 		ret = btrfs_recover_log_trees(log_tree_root);
2882 		if (ret) {
2883 			btrfs_error(tree_root->fs_info, ret,
2884 				    "Failed to recover log tree");
2885 			free_extent_buffer(log_tree_root->node);
2886 			kfree(log_tree_root);
2887 			goto fail_qgroup;
2888 		}
2889 
2890 		if (sb->s_flags & MS_RDONLY) {
2891 			ret = btrfs_commit_super(tree_root);
2892 			if (ret)
2893 				goto fail_qgroup;
2894 		}
2895 	}
2896 
2897 	ret = btrfs_find_orphan_roots(tree_root);
2898 	if (ret)
2899 		goto fail_qgroup;
2900 
2901 	if (!(sb->s_flags & MS_RDONLY)) {
2902 		ret = btrfs_cleanup_fs_roots(fs_info);
2903 		if (ret)
2904 			goto fail_qgroup;
2905 
2906 		mutex_lock(&fs_info->cleaner_mutex);
2907 		ret = btrfs_recover_relocation(tree_root);
2908 		mutex_unlock(&fs_info->cleaner_mutex);
2909 		if (ret < 0) {
2910 			printk(KERN_WARNING
2911 			       "BTRFS: failed to recover relocation\n");
2912 			err = -EINVAL;
2913 			goto fail_qgroup;
2914 		}
2915 	}
2916 
2917 	location.objectid = BTRFS_FS_TREE_OBJECTID;
2918 	location.type = BTRFS_ROOT_ITEM_KEY;
2919 	location.offset = 0;
2920 
2921 	fs_info->fs_root = btrfs_read_fs_root_no_name(fs_info, &location);
2922 	if (IS_ERR(fs_info->fs_root)) {
2923 		err = PTR_ERR(fs_info->fs_root);
2924 		goto fail_qgroup;
2925 	}
2926 
2927 	if (sb->s_flags & MS_RDONLY)
2928 		return 0;
2929 
2930 	down_read(&fs_info->cleanup_work_sem);
2931 	if ((ret = btrfs_orphan_cleanup(fs_info->fs_root)) ||
2932 	    (ret = btrfs_orphan_cleanup(fs_info->tree_root))) {
2933 		up_read(&fs_info->cleanup_work_sem);
2934 		close_ctree(tree_root);
2935 		return ret;
2936 	}
2937 	up_read(&fs_info->cleanup_work_sem);
2938 
2939 	ret = btrfs_resume_balance_async(fs_info);
2940 	if (ret) {
2941 		printk(KERN_WARNING "BTRFS: failed to resume balance\n");
2942 		close_ctree(tree_root);
2943 		return ret;
2944 	}
2945 
2946 	ret = btrfs_resume_dev_replace_async(fs_info);
2947 	if (ret) {
2948 		pr_warn("BTRFS: failed to resume dev_replace\n");
2949 		close_ctree(tree_root);
2950 		return ret;
2951 	}
2952 
2953 	btrfs_qgroup_rescan_resume(fs_info);
2954 
2955 	if (create_uuid_tree) {
2956 		pr_info("BTRFS: creating UUID tree\n");
2957 		ret = btrfs_create_uuid_tree(fs_info);
2958 		if (ret) {
2959 			pr_warn("BTRFS: failed to create the UUID tree %d\n",
2960 				ret);
2961 			close_ctree(tree_root);
2962 			return ret;
2963 		}
2964 	} else if (check_uuid_tree ||
2965 		   btrfs_test_opt(tree_root, RESCAN_UUID_TREE)) {
2966 		pr_info("BTRFS: checking UUID tree\n");
2967 		ret = btrfs_check_uuid_tree(fs_info);
2968 		if (ret) {
2969 			pr_warn("BTRFS: failed to check the UUID tree %d\n",
2970 				ret);
2971 			close_ctree(tree_root);
2972 			return ret;
2973 		}
2974 	} else {
2975 		fs_info->update_uuid_tree_gen = 1;
2976 	}
2977 
2978 	return 0;
2979 
2980 fail_qgroup:
2981 	btrfs_free_qgroup_config(fs_info);
2982 fail_trans_kthread:
2983 	kthread_stop(fs_info->transaction_kthread);
2984 	btrfs_cleanup_transaction(fs_info->tree_root);
2985 	btrfs_free_fs_roots(fs_info);
2986 fail_cleaner:
2987 	kthread_stop(fs_info->cleaner_kthread);
2988 
2989 	/*
2990 	 * make sure we're done with the btree inode before we stop our
2991 	 * kthreads
2992 	 */
2993 	filemap_write_and_wait(fs_info->btree_inode->i_mapping);
2994 
2995 fail_sysfs:
2996 	btrfs_sysfs_remove_one(fs_info);
2997 
2998 fail_block_groups:
2999 	btrfs_put_block_group_cache(fs_info);
3000 	btrfs_free_block_groups(fs_info);
3001 
3002 fail_tree_roots:
3003 	free_root_pointers(fs_info, 1);
3004 	invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
3005 
3006 fail_sb_buffer:
3007 	btrfs_stop_all_workers(fs_info);
3008 fail_alloc:
3009 fail_iput:
3010 	btrfs_mapping_tree_free(&fs_info->mapping_tree);
3011 
3012 	iput(fs_info->btree_inode);
3013 fail_bio_counter:
3014 	percpu_counter_destroy(&fs_info->bio_counter);
3015 fail_delalloc_bytes:
3016 	percpu_counter_destroy(&fs_info->delalloc_bytes);
3017 fail_dirty_metadata_bytes:
3018 	percpu_counter_destroy(&fs_info->dirty_metadata_bytes);
3019 fail_bdi:
3020 	bdi_destroy(&fs_info->bdi);
3021 fail_srcu:
3022 	cleanup_srcu_struct(&fs_info->subvol_srcu);
3023 fail:
3024 	btrfs_free_stripe_hash_table(fs_info);
3025 	btrfs_close_devices(fs_info->fs_devices);
3026 	return err;
3027 
3028 recovery_tree_root:
3029 	if (!btrfs_test_opt(tree_root, RECOVERY))
3030 		goto fail_tree_roots;
3031 
3032 	free_root_pointers(fs_info, 0);
3033 
3034 	/* don't use the log in recovery mode, it won't be valid */
3035 	btrfs_set_super_log_root(disk_super, 0);
3036 
3037 	/* we can't trust the free space cache either */
3038 	btrfs_set_opt(fs_info->mount_opt, CLEAR_CACHE);
3039 
3040 	ret = next_root_backup(fs_info, fs_info->super_copy,
3041 			       &num_backups_tried, &backup_index);
3042 	if (ret == -1)
3043 		goto fail_block_groups;
3044 	goto retry_root_backup;
3045 }
3046 
3047 static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
3048 {
3049 	if (uptodate) {
3050 		set_buffer_uptodate(bh);
3051 	} else {
3052 		struct btrfs_device *device = (struct btrfs_device *)
3053 			bh->b_private;
3054 
3055 		printk_ratelimited_in_rcu(KERN_WARNING "BTRFS: lost page write due to "
3056 					  "I/O error on %s\n",
3057 					  rcu_str_deref(device->name));
3058 		/* note, we dont' set_buffer_write_io_error because we have
3059 		 * our own ways of dealing with the IO errors
3060 		 */
3061 		clear_buffer_uptodate(bh);
3062 		btrfs_dev_stat_inc_and_print(device, BTRFS_DEV_STAT_WRITE_ERRS);
3063 	}
3064 	unlock_buffer(bh);
3065 	put_bh(bh);
3066 }
3067 
3068 struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
3069 {
3070 	struct buffer_head *bh;
3071 	struct buffer_head *latest = NULL;
3072 	struct btrfs_super_block *super;
3073 	int i;
3074 	u64 transid = 0;
3075 	u64 bytenr;
3076 
3077 	/* we would like to check all the supers, but that would make
3078 	 * a btrfs mount succeed after a mkfs from a different FS.
3079 	 * So, we need to add a special mount option to scan for
3080 	 * later supers, using BTRFS_SUPER_MIRROR_MAX instead
3081 	 */
3082 	for (i = 0; i < 1; i++) {
3083 		bytenr = btrfs_sb_offset(i);
3084 		if (bytenr + BTRFS_SUPER_INFO_SIZE >=
3085 					i_size_read(bdev->bd_inode))
3086 			break;
3087 		bh = __bread(bdev, bytenr / 4096,
3088 					BTRFS_SUPER_INFO_SIZE);
3089 		if (!bh)
3090 			continue;
3091 
3092 		super = (struct btrfs_super_block *)bh->b_data;
3093 		if (btrfs_super_bytenr(super) != bytenr ||
3094 		    btrfs_super_magic(super) != BTRFS_MAGIC) {
3095 			brelse(bh);
3096 			continue;
3097 		}
3098 
3099 		if (!latest || btrfs_super_generation(super) > transid) {
3100 			brelse(latest);
3101 			latest = bh;
3102 			transid = btrfs_super_generation(super);
3103 		} else {
3104 			brelse(bh);
3105 		}
3106 	}
3107 	return latest;
3108 }
3109 
3110 /*
3111  * this should be called twice, once with wait == 0 and
3112  * once with wait == 1.  When wait == 0 is done, all the buffer heads
3113  * we write are pinned.
3114  *
3115  * They are released when wait == 1 is done.
3116  * max_mirrors must be the same for both runs, and it indicates how
3117  * many supers on this one device should be written.
3118  *
3119  * max_mirrors == 0 means to write them all.
3120  */
3121 static int write_dev_supers(struct btrfs_device *device,
3122 			    struct btrfs_super_block *sb,
3123 			    int do_barriers, int wait, int max_mirrors)
3124 {
3125 	struct buffer_head *bh;
3126 	int i;
3127 	int ret;
3128 	int errors = 0;
3129 	u32 crc;
3130 	u64 bytenr;
3131 
3132 	if (max_mirrors == 0)
3133 		max_mirrors = BTRFS_SUPER_MIRROR_MAX;
3134 
3135 	for (i = 0; i < max_mirrors; i++) {
3136 		bytenr = btrfs_sb_offset(i);
3137 		if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
3138 			break;
3139 
3140 		if (wait) {
3141 			bh = __find_get_block(device->bdev, bytenr / 4096,
3142 					      BTRFS_SUPER_INFO_SIZE);
3143 			if (!bh) {
3144 				errors++;
3145 				continue;
3146 			}
3147 			wait_on_buffer(bh);
3148 			if (!buffer_uptodate(bh))
3149 				errors++;
3150 
3151 			/* drop our reference */
3152 			brelse(bh);
3153 
3154 			/* drop the reference from the wait == 0 run */
3155 			brelse(bh);
3156 			continue;
3157 		} else {
3158 			btrfs_set_super_bytenr(sb, bytenr);
3159 
3160 			crc = ~(u32)0;
3161 			crc = btrfs_csum_data((char *)sb +
3162 					      BTRFS_CSUM_SIZE, crc,
3163 					      BTRFS_SUPER_INFO_SIZE -
3164 					      BTRFS_CSUM_SIZE);
3165 			btrfs_csum_final(crc, sb->csum);
3166 
3167 			/*
3168 			 * one reference for us, and we leave it for the
3169 			 * caller
3170 			 */
3171 			bh = __getblk(device->bdev, bytenr / 4096,
3172 				      BTRFS_SUPER_INFO_SIZE);
3173 			if (!bh) {
3174 				printk(KERN_ERR "BTRFS: couldn't get super "
3175 				       "buffer head for bytenr %Lu\n", bytenr);
3176 				errors++;
3177 				continue;
3178 			}
3179 
3180 			memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
3181 
3182 			/* one reference for submit_bh */
3183 			get_bh(bh);
3184 
3185 			set_buffer_uptodate(bh);
3186 			lock_buffer(bh);
3187 			bh->b_end_io = btrfs_end_buffer_write_sync;
3188 			bh->b_private = device;
3189 		}
3190 
3191 		/*
3192 		 * we fua the first super.  The others we allow
3193 		 * to go down lazy.
3194 		 */
3195 		if (i == 0)
3196 			ret = btrfsic_submit_bh(WRITE_FUA, bh);
3197 		else
3198 			ret = btrfsic_submit_bh(WRITE_SYNC, bh);
3199 		if (ret)
3200 			errors++;
3201 	}
3202 	return errors < i ? 0 : -1;
3203 }
3204 
3205 /*
3206  * endio for the write_dev_flush, this will wake anyone waiting
3207  * for the barrier when it is done
3208  */
3209 static void btrfs_end_empty_barrier(struct bio *bio, int err)
3210 {
3211 	if (err) {
3212 		if (err == -EOPNOTSUPP)
3213 			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
3214 		clear_bit(BIO_UPTODATE, &bio->bi_flags);
3215 	}
3216 	if (bio->bi_private)
3217 		complete(bio->bi_private);
3218 	bio_put(bio);
3219 }
3220 
3221 /*
3222  * trigger flushes for one the devices.  If you pass wait == 0, the flushes are
3223  * sent down.  With wait == 1, it waits for the previous flush.
3224  *
3225  * any device where the flush fails with eopnotsupp are flagged as not-barrier
3226  * capable
3227  */
3228 static int write_dev_flush(struct btrfs_device *device, int wait)
3229 {
3230 	struct bio *bio;
3231 	int ret = 0;
3232 
3233 	if (device->nobarriers)
3234 		return 0;
3235 
3236 	if (wait) {
3237 		bio = device->flush_bio;
3238 		if (!bio)
3239 			return 0;
3240 
3241 		wait_for_completion(&device->flush_wait);
3242 
3243 		if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
3244 			printk_in_rcu("BTRFS: disabling barriers on dev %s\n",
3245 				      rcu_str_deref(device->name));
3246 			device->nobarriers = 1;
3247 		} else if (!bio_flagged(bio, BIO_UPTODATE)) {
3248 			ret = -EIO;
3249 			btrfs_dev_stat_inc_and_print(device,
3250 				BTRFS_DEV_STAT_FLUSH_ERRS);
3251 		}
3252 
3253 		/* drop the reference from the wait == 0 run */
3254 		bio_put(bio);
3255 		device->flush_bio = NULL;
3256 
3257 		return ret;
3258 	}
3259 
3260 	/*
3261 	 * one reference for us, and we leave it for the
3262 	 * caller
3263 	 */
3264 	device->flush_bio = NULL;
3265 	bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
3266 	if (!bio)
3267 		return -ENOMEM;
3268 
3269 	bio->bi_end_io = btrfs_end_empty_barrier;
3270 	bio->bi_bdev = device->bdev;
3271 	init_completion(&device->flush_wait);
3272 	bio->bi_private = &device->flush_wait;
3273 	device->flush_bio = bio;
3274 
3275 	bio_get(bio);
3276 	btrfsic_submit_bio(WRITE_FLUSH, bio);
3277 
3278 	return 0;
3279 }
3280 
3281 /*
3282  * send an empty flush down to each device in parallel,
3283  * then wait for them
3284  */
3285 static int barrier_all_devices(struct btrfs_fs_info *info)
3286 {
3287 	struct list_head *head;
3288 	struct btrfs_device *dev;
3289 	int errors_send = 0;
3290 	int errors_wait = 0;
3291 	int ret;
3292 
3293 	/* send down all the barriers */
3294 	head = &info->fs_devices->devices;
3295 	list_for_each_entry_rcu(dev, head, dev_list) {
3296 		if (dev->missing)
3297 			continue;
3298 		if (!dev->bdev) {
3299 			errors_send++;
3300 			continue;
3301 		}
3302 		if (!dev->in_fs_metadata || !dev->writeable)
3303 			continue;
3304 
3305 		ret = write_dev_flush(dev, 0);
3306 		if (ret)
3307 			errors_send++;
3308 	}
3309 
3310 	/* wait for all the barriers */
3311 	list_for_each_entry_rcu(dev, head, dev_list) {
3312 		if (dev->missing)
3313 			continue;
3314 		if (!dev->bdev) {
3315 			errors_wait++;
3316 			continue;
3317 		}
3318 		if (!dev->in_fs_metadata || !dev->writeable)
3319 			continue;
3320 
3321 		ret = write_dev_flush(dev, 1);
3322 		if (ret)
3323 			errors_wait++;
3324 	}
3325 	if (errors_send > info->num_tolerated_disk_barrier_failures ||
3326 	    errors_wait > info->num_tolerated_disk_barrier_failures)
3327 		return -EIO;
3328 	return 0;
3329 }
3330 
3331 int btrfs_calc_num_tolerated_disk_barrier_failures(
3332 	struct btrfs_fs_info *fs_info)
3333 {
3334 	struct btrfs_ioctl_space_info space;
3335 	struct btrfs_space_info *sinfo;
3336 	u64 types[] = {BTRFS_BLOCK_GROUP_DATA,
3337 		       BTRFS_BLOCK_GROUP_SYSTEM,
3338 		       BTRFS_BLOCK_GROUP_METADATA,
3339 		       BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA};
3340 	int num_types = 4;
3341 	int i;
3342 	int c;
3343 	int num_tolerated_disk_barrier_failures =
3344 		(int)fs_info->fs_devices->num_devices;
3345 
3346 	for (i = 0; i < num_types; i++) {
3347 		struct btrfs_space_info *tmp;
3348 
3349 		sinfo = NULL;
3350 		rcu_read_lock();
3351 		list_for_each_entry_rcu(tmp, &fs_info->space_info, list) {
3352 			if (tmp->flags == types[i]) {
3353 				sinfo = tmp;
3354 				break;
3355 			}
3356 		}
3357 		rcu_read_unlock();
3358 
3359 		if (!sinfo)
3360 			continue;
3361 
3362 		down_read(&sinfo->groups_sem);
3363 		for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
3364 			if (!list_empty(&sinfo->block_groups[c])) {
3365 				u64 flags;
3366 
3367 				btrfs_get_block_group_info(
3368 					&sinfo->block_groups[c], &space);
3369 				if (space.total_bytes == 0 ||
3370 				    space.used_bytes == 0)
3371 					continue;
3372 				flags = space.flags;
3373 				/*
3374 				 * return
3375 				 * 0: if dup, single or RAID0 is configured for
3376 				 *    any of metadata, system or data, else
3377 				 * 1: if RAID5 is configured, or if RAID1 or
3378 				 *    RAID10 is configured and only two mirrors
3379 				 *    are used, else
3380 				 * 2: if RAID6 is configured, else
3381 				 * num_mirrors - 1: if RAID1 or RAID10 is
3382 				 *                  configured and more than
3383 				 *                  2 mirrors are used.
3384 				 */
3385 				if (num_tolerated_disk_barrier_failures > 0 &&
3386 				    ((flags & (BTRFS_BLOCK_GROUP_DUP |
3387 					       BTRFS_BLOCK_GROUP_RAID0)) ||
3388 				     ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK)
3389 				      == 0)))
3390 					num_tolerated_disk_barrier_failures = 0;
3391 				else if (num_tolerated_disk_barrier_failures > 1) {
3392 					if (flags & (BTRFS_BLOCK_GROUP_RAID1 |
3393 					    BTRFS_BLOCK_GROUP_RAID5 |
3394 					    BTRFS_BLOCK_GROUP_RAID10)) {
3395 						num_tolerated_disk_barrier_failures = 1;
3396 					} else if (flags &
3397 						   BTRFS_BLOCK_GROUP_RAID6) {
3398 						num_tolerated_disk_barrier_failures = 2;
3399 					}
3400 				}
3401 			}
3402 		}
3403 		up_read(&sinfo->groups_sem);
3404 	}
3405 
3406 	return num_tolerated_disk_barrier_failures;
3407 }
3408 
3409 static int write_all_supers(struct btrfs_root *root, int max_mirrors)
3410 {
3411 	struct list_head *head;
3412 	struct btrfs_device *dev;
3413 	struct btrfs_super_block *sb;
3414 	struct btrfs_dev_item *dev_item;
3415 	int ret;
3416 	int do_barriers;
3417 	int max_errors;
3418 	int total_errors = 0;
3419 	u64 flags;
3420 
3421 	do_barriers = !btrfs_test_opt(root, NOBARRIER);
3422 	backup_super_roots(root->fs_info);
3423 
3424 	sb = root->fs_info->super_for_commit;
3425 	dev_item = &sb->dev_item;
3426 
3427 	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
3428 	head = &root->fs_info->fs_devices->devices;
3429 	max_errors = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
3430 
3431 	if (do_barriers) {
3432 		ret = barrier_all_devices(root->fs_info);
3433 		if (ret) {
3434 			mutex_unlock(
3435 				&root->fs_info->fs_devices->device_list_mutex);
3436 			btrfs_error(root->fs_info, ret,
3437 				    "errors while submitting device barriers.");
3438 			return ret;
3439 		}
3440 	}
3441 
3442 	list_for_each_entry_rcu(dev, head, dev_list) {
3443 		if (!dev->bdev) {
3444 			total_errors++;
3445 			continue;
3446 		}
3447 		if (!dev->in_fs_metadata || !dev->writeable)
3448 			continue;
3449 
3450 		btrfs_set_stack_device_generation(dev_item, 0);
3451 		btrfs_set_stack_device_type(dev_item, dev->type);
3452 		btrfs_set_stack_device_id(dev_item, dev->devid);
3453 		btrfs_set_stack_device_total_bytes(dev_item, dev->total_bytes);
3454 		btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
3455 		btrfs_set_stack_device_io_align(dev_item, dev->io_align);
3456 		btrfs_set_stack_device_io_width(dev_item, dev->io_width);
3457 		btrfs_set_stack_device_sector_size(dev_item, dev->sector_size);
3458 		memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE);
3459 		memcpy(dev_item->fsid, dev->fs_devices->fsid, BTRFS_UUID_SIZE);
3460 
3461 		flags = btrfs_super_flags(sb);
3462 		btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
3463 
3464 		ret = write_dev_supers(dev, sb, do_barriers, 0, max_mirrors);
3465 		if (ret)
3466 			total_errors++;
3467 	}
3468 	if (total_errors > max_errors) {
3469 		btrfs_err(root->fs_info, "%d errors while writing supers",
3470 		       total_errors);
3471 		mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
3472 
3473 		/* FUA is masked off if unsupported and can't be the reason */
3474 		btrfs_error(root->fs_info, -EIO,
3475 			    "%d errors while writing supers", total_errors);
3476 		return -EIO;
3477 	}
3478 
3479 	total_errors = 0;
3480 	list_for_each_entry_rcu(dev, head, dev_list) {
3481 		if (!dev->bdev)
3482 			continue;
3483 		if (!dev->in_fs_metadata || !dev->writeable)
3484 			continue;
3485 
3486 		ret = write_dev_supers(dev, sb, do_barriers, 1, max_mirrors);
3487 		if (ret)
3488 			total_errors++;
3489 	}
3490 	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
3491 	if (total_errors > max_errors) {
3492 		btrfs_error(root->fs_info, -EIO,
3493 			    "%d errors while writing supers", total_errors);
3494 		return -EIO;
3495 	}
3496 	return 0;
3497 }
3498 
3499 int write_ctree_super(struct btrfs_trans_handle *trans,
3500 		      struct btrfs_root *root, int max_mirrors)
3501 {
3502 	return write_all_supers(root, max_mirrors);
3503 }
3504 
3505 /* Drop a fs root from the radix tree and free it. */
3506 void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
3507 				  struct btrfs_root *root)
3508 {
3509 	spin_lock(&fs_info->fs_roots_radix_lock);
3510 	radix_tree_delete(&fs_info->fs_roots_radix,
3511 			  (unsigned long)root->root_key.objectid);
3512 	spin_unlock(&fs_info->fs_roots_radix_lock);
3513 
3514 	if (btrfs_root_refs(&root->root_item) == 0)
3515 		synchronize_srcu(&fs_info->subvol_srcu);
3516 
3517 	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
3518 		btrfs_free_log(NULL, root);
3519 
3520 	if (root->free_ino_pinned)
3521 		__btrfs_remove_free_space_cache(root->free_ino_pinned);
3522 	if (root->free_ino_ctl)
3523 		__btrfs_remove_free_space_cache(root->free_ino_ctl);
3524 	free_fs_root(root);
3525 }
3526 
3527 static void free_fs_root(struct btrfs_root *root)
3528 {
3529 	iput(root->cache_inode);
3530 	WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
3531 	btrfs_free_block_rsv(root, root->orphan_block_rsv);
3532 	root->orphan_block_rsv = NULL;
3533 	if (root->anon_dev)
3534 		free_anon_bdev(root->anon_dev);
3535 	if (root->subv_writers)
3536 		btrfs_free_subvolume_writers(root->subv_writers);
3537 	free_extent_buffer(root->node);
3538 	free_extent_buffer(root->commit_root);
3539 	kfree(root->free_ino_ctl);
3540 	kfree(root->free_ino_pinned);
3541 	kfree(root->name);
3542 	btrfs_put_fs_root(root);
3543 }
3544 
3545 void btrfs_free_fs_root(struct btrfs_root *root)
3546 {
3547 	free_fs_root(root);
3548 }
3549 
3550 int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)
3551 {
3552 	u64 root_objectid = 0;
3553 	struct btrfs_root *gang[8];
3554 	int i = 0;
3555 	int err = 0;
3556 	unsigned int ret = 0;
3557 	int index;
3558 
3559 	while (1) {
3560 		index = srcu_read_lock(&fs_info->subvol_srcu);
3561 		ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
3562 					     (void **)gang, root_objectid,
3563 					     ARRAY_SIZE(gang));
3564 		if (!ret) {
3565 			srcu_read_unlock(&fs_info->subvol_srcu, index);
3566 			break;
3567 		}
3568 		root_objectid = gang[ret - 1]->root_key.objectid + 1;
3569 
3570 		for (i = 0; i < ret; i++) {
3571 			/* Avoid to grab roots in dead_roots */
3572 			if (btrfs_root_refs(&gang[i]->root_item) == 0) {
3573 				gang[i] = NULL;
3574 				continue;
3575 			}
3576 			/* grab all the search result for later use */
3577 			gang[i] = btrfs_grab_fs_root(gang[i]);
3578 		}
3579 		srcu_read_unlock(&fs_info->subvol_srcu, index);
3580 
3581 		for (i = 0; i < ret; i++) {
3582 			if (!gang[i])
3583 				continue;
3584 			root_objectid = gang[i]->root_key.objectid;
3585 			err = btrfs_orphan_cleanup(gang[i]);
3586 			if (err)
3587 				break;
3588 			btrfs_put_fs_root(gang[i]);
3589 		}
3590 		root_objectid++;
3591 	}
3592 
3593 	/* release the uncleaned roots due to error */
3594 	for (; i < ret; i++) {
3595 		if (gang[i])
3596 			btrfs_put_fs_root(gang[i]);
3597 	}
3598 	return err;
3599 }
3600 
3601 int btrfs_commit_super(struct btrfs_root *root)
3602 {
3603 	struct btrfs_trans_handle *trans;
3604 
3605 	mutex_lock(&root->fs_info->cleaner_mutex);
3606 	btrfs_run_delayed_iputs(root);
3607 	mutex_unlock(&root->fs_info->cleaner_mutex);
3608 	wake_up_process(root->fs_info->cleaner_kthread);
3609 
3610 	/* wait until ongoing cleanup work done */
3611 	down_write(&root->fs_info->cleanup_work_sem);
3612 	up_write(&root->fs_info->cleanup_work_sem);
3613 
3614 	trans = btrfs_join_transaction(root);
3615 	if (IS_ERR(trans))
3616 		return PTR_ERR(trans);
3617 	return btrfs_commit_transaction(trans, root);
3618 }
3619 
3620 int close_ctree(struct btrfs_root *root)
3621 {
3622 	struct btrfs_fs_info *fs_info = root->fs_info;
3623 	int ret;
3624 
3625 	fs_info->closing = 1;
3626 	smp_mb();
3627 
3628 	/* wait for the uuid_scan task to finish */
3629 	down(&fs_info->uuid_tree_rescan_sem);
3630 	/* avoid complains from lockdep et al., set sem back to initial state */
3631 	up(&fs_info->uuid_tree_rescan_sem);
3632 
3633 	/* pause restriper - we want to resume on mount */
3634 	btrfs_pause_balance(fs_info);
3635 
3636 	btrfs_dev_replace_suspend_for_unmount(fs_info);
3637 
3638 	btrfs_scrub_cancel(fs_info);
3639 
3640 	/* wait for any defraggers to finish */
3641 	wait_event(fs_info->transaction_wait,
3642 		   (atomic_read(&fs_info->defrag_running) == 0));
3643 
3644 	/* clear out the rbtree of defraggable inodes */
3645 	btrfs_cleanup_defrag_inodes(fs_info);
3646 
3647 	cancel_work_sync(&fs_info->async_reclaim_work);
3648 
3649 	if (!(fs_info->sb->s_flags & MS_RDONLY)) {
3650 		ret = btrfs_commit_super(root);
3651 		if (ret)
3652 			btrfs_err(root->fs_info, "commit super ret %d", ret);
3653 	}
3654 
3655 	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
3656 		btrfs_error_commit_super(root);
3657 
3658 	kthread_stop(fs_info->transaction_kthread);
3659 	kthread_stop(fs_info->cleaner_kthread);
3660 
3661 	fs_info->closing = 2;
3662 	smp_mb();
3663 
3664 	btrfs_free_qgroup_config(root->fs_info);
3665 
3666 	if (percpu_counter_sum(&fs_info->delalloc_bytes)) {
3667 		btrfs_info(root->fs_info, "at unmount delalloc count %lld",
3668 		       percpu_counter_sum(&fs_info->delalloc_bytes));
3669 	}
3670 
3671 	btrfs_sysfs_remove_one(fs_info);
3672 
3673 	btrfs_free_fs_roots(fs_info);
3674 
3675 	btrfs_put_block_group_cache(fs_info);
3676 
3677 	btrfs_free_block_groups(fs_info);
3678 
3679 	/*
3680 	 * we must make sure there is not any read request to
3681 	 * submit after we stopping all workers.
3682 	 */
3683 	invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
3684 	btrfs_stop_all_workers(fs_info);
3685 
3686 	free_root_pointers(fs_info, 1);
3687 
3688 	iput(fs_info->btree_inode);
3689 
3690 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
3691 	if (btrfs_test_opt(root, CHECK_INTEGRITY))
3692 		btrfsic_unmount(root, fs_info->fs_devices);
3693 #endif
3694 
3695 	btrfs_close_devices(fs_info->fs_devices);
3696 	btrfs_mapping_tree_free(&fs_info->mapping_tree);
3697 
3698 	percpu_counter_destroy(&fs_info->dirty_metadata_bytes);
3699 	percpu_counter_destroy(&fs_info->delalloc_bytes);
3700 	percpu_counter_destroy(&fs_info->bio_counter);
3701 	bdi_destroy(&fs_info->bdi);
3702 	cleanup_srcu_struct(&fs_info->subvol_srcu);
3703 
3704 	btrfs_free_stripe_hash_table(fs_info);
3705 
3706 	btrfs_free_block_rsv(root, root->orphan_block_rsv);
3707 	root->orphan_block_rsv = NULL;
3708 
3709 	return 0;
3710 }
3711 
3712 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
3713 			  int atomic)
3714 {
3715 	int ret;
3716 	struct inode *btree_inode = buf->pages[0]->mapping->host;
3717 
3718 	ret = extent_buffer_uptodate(buf);
3719 	if (!ret)
3720 		return ret;
3721 
3722 	ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
3723 				    parent_transid, atomic);
3724 	if (ret == -EAGAIN)
3725 		return ret;
3726 	return !ret;
3727 }
3728 
3729 int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
3730 {
3731 	return set_extent_buffer_uptodate(buf);
3732 }
3733 
3734 void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
3735 {
3736 	struct btrfs_root *root;
3737 	u64 transid = btrfs_header_generation(buf);
3738 	int was_dirty;
3739 
3740 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
3741 	/*
3742 	 * This is a fast path so only do this check if we have sanity tests
3743 	 * enabled.  Normal people shouldn't be marking dummy buffers as dirty
3744 	 * outside of the sanity tests.
3745 	 */
3746 	if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &buf->bflags)))
3747 		return;
3748 #endif
3749 	root = BTRFS_I(buf->pages[0]->mapping->host)->root;
3750 	btrfs_assert_tree_locked(buf);
3751 	if (transid != root->fs_info->generation)
3752 		WARN(1, KERN_CRIT "btrfs transid mismatch buffer %llu, "
3753 		       "found %llu running %llu\n",
3754 			buf->start, transid, root->fs_info->generation);
3755 	was_dirty = set_extent_buffer_dirty(buf);
3756 	if (!was_dirty)
3757 		__percpu_counter_add(&root->fs_info->dirty_metadata_bytes,
3758 				     buf->len,
3759 				     root->fs_info->dirty_metadata_batch);
3760 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
3761 	if (btrfs_header_level(buf) == 0 && check_leaf(root, buf)) {
3762 		btrfs_print_leaf(root, buf);
3763 		ASSERT(0);
3764 	}
3765 #endif
3766 }
3767 
3768 static void __btrfs_btree_balance_dirty(struct btrfs_root *root,
3769 					int flush_delayed)
3770 {
3771 	/*
3772 	 * looks as though older kernels can get into trouble with
3773 	 * this code, they end up stuck in balance_dirty_pages forever
3774 	 */
3775 	int ret;
3776 
3777 	if (current->flags & PF_MEMALLOC)
3778 		return;
3779 
3780 	if (flush_delayed)
3781 		btrfs_balance_delayed_items(root);
3782 
3783 	ret = percpu_counter_compare(&root->fs_info->dirty_metadata_bytes,
3784 				     BTRFS_DIRTY_METADATA_THRESH);
3785 	if (ret > 0) {
3786 		balance_dirty_pages_ratelimited(
3787 				   root->fs_info->btree_inode->i_mapping);
3788 	}
3789 	return;
3790 }
3791 
3792 void btrfs_btree_balance_dirty(struct btrfs_root *root)
3793 {
3794 	__btrfs_btree_balance_dirty(root, 1);
3795 }
3796 
3797 void btrfs_btree_balance_dirty_nodelay(struct btrfs_root *root)
3798 {
3799 	__btrfs_btree_balance_dirty(root, 0);
3800 }
3801 
3802 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
3803 {
3804 	struct btrfs_root *root = BTRFS_I(buf->pages[0]->mapping->host)->root;
3805 	return btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
3806 }
3807 
3808 static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
3809 			      int read_only)
3810 {
3811 	/*
3812 	 * Placeholder for checks
3813 	 */
3814 	return 0;
3815 }
3816 
3817 static void btrfs_error_commit_super(struct btrfs_root *root)
3818 {
3819 	mutex_lock(&root->fs_info->cleaner_mutex);
3820 	btrfs_run_delayed_iputs(root);
3821 	mutex_unlock(&root->fs_info->cleaner_mutex);
3822 
3823 	down_write(&root->fs_info->cleanup_work_sem);
3824 	up_write(&root->fs_info->cleanup_work_sem);
3825 
3826 	/* cleanup FS via transaction */
3827 	btrfs_cleanup_transaction(root);
3828 }
3829 
3830 static void btrfs_destroy_ordered_extents(struct btrfs_root *root)
3831 {
3832 	struct btrfs_ordered_extent *ordered;
3833 
3834 	spin_lock(&root->ordered_extent_lock);
3835 	/*
3836 	 * This will just short circuit the ordered completion stuff which will
3837 	 * make sure the ordered extent gets properly cleaned up.
3838 	 */
3839 	list_for_each_entry(ordered, &root->ordered_extents,
3840 			    root_extent_list)
3841 		set_bit(BTRFS_ORDERED_IOERR, &ordered->flags);
3842 	spin_unlock(&root->ordered_extent_lock);
3843 }
3844 
3845 static void btrfs_destroy_all_ordered_extents(struct btrfs_fs_info *fs_info)
3846 {
3847 	struct btrfs_root *root;
3848 	struct list_head splice;
3849 
3850 	INIT_LIST_HEAD(&splice);
3851 
3852 	spin_lock(&fs_info->ordered_root_lock);
3853 	list_splice_init(&fs_info->ordered_roots, &splice);
3854 	while (!list_empty(&splice)) {
3855 		root = list_first_entry(&splice, struct btrfs_root,
3856 					ordered_root);
3857 		list_move_tail(&root->ordered_root,
3858 			       &fs_info->ordered_roots);
3859 
3860 		spin_unlock(&fs_info->ordered_root_lock);
3861 		btrfs_destroy_ordered_extents(root);
3862 
3863 		cond_resched();
3864 		spin_lock(&fs_info->ordered_root_lock);
3865 	}
3866 	spin_unlock(&fs_info->ordered_root_lock);
3867 }
3868 
3869 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
3870 				      struct btrfs_root *root)
3871 {
3872 	struct rb_node *node;
3873 	struct btrfs_delayed_ref_root *delayed_refs;
3874 	struct btrfs_delayed_ref_node *ref;
3875 	int ret = 0;
3876 
3877 	delayed_refs = &trans->delayed_refs;
3878 
3879 	spin_lock(&delayed_refs->lock);
3880 	if (atomic_read(&delayed_refs->num_entries) == 0) {
3881 		spin_unlock(&delayed_refs->lock);
3882 		btrfs_info(root->fs_info, "delayed_refs has NO entry");
3883 		return ret;
3884 	}
3885 
3886 	while ((node = rb_first(&delayed_refs->href_root)) != NULL) {
3887 		struct btrfs_delayed_ref_head *head;
3888 		bool pin_bytes = false;
3889 
3890 		head = rb_entry(node, struct btrfs_delayed_ref_head,
3891 				href_node);
3892 		if (!mutex_trylock(&head->mutex)) {
3893 			atomic_inc(&head->node.refs);
3894 			spin_unlock(&delayed_refs->lock);
3895 
3896 			mutex_lock(&head->mutex);
3897 			mutex_unlock(&head->mutex);
3898 			btrfs_put_delayed_ref(&head->node);
3899 			spin_lock(&delayed_refs->lock);
3900 			continue;
3901 		}
3902 		spin_lock(&head->lock);
3903 		while ((node = rb_first(&head->ref_root)) != NULL) {
3904 			ref = rb_entry(node, struct btrfs_delayed_ref_node,
3905 				       rb_node);
3906 			ref->in_tree = 0;
3907 			rb_erase(&ref->rb_node, &head->ref_root);
3908 			atomic_dec(&delayed_refs->num_entries);
3909 			btrfs_put_delayed_ref(ref);
3910 		}
3911 		if (head->must_insert_reserved)
3912 			pin_bytes = true;
3913 		btrfs_free_delayed_extent_op(head->extent_op);
3914 		delayed_refs->num_heads--;
3915 		if (head->processing == 0)
3916 			delayed_refs->num_heads_ready--;
3917 		atomic_dec(&delayed_refs->num_entries);
3918 		head->node.in_tree = 0;
3919 		rb_erase(&head->href_node, &delayed_refs->href_root);
3920 		spin_unlock(&head->lock);
3921 		spin_unlock(&delayed_refs->lock);
3922 		mutex_unlock(&head->mutex);
3923 
3924 		if (pin_bytes)
3925 			btrfs_pin_extent(root, head->node.bytenr,
3926 					 head->node.num_bytes, 1);
3927 		btrfs_put_delayed_ref(&head->node);
3928 		cond_resched();
3929 		spin_lock(&delayed_refs->lock);
3930 	}
3931 
3932 	spin_unlock(&delayed_refs->lock);
3933 
3934 	return ret;
3935 }
3936 
3937 static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root)
3938 {
3939 	struct btrfs_inode *btrfs_inode;
3940 	struct list_head splice;
3941 
3942 	INIT_LIST_HEAD(&splice);
3943 
3944 	spin_lock(&root->delalloc_lock);
3945 	list_splice_init(&root->delalloc_inodes, &splice);
3946 
3947 	while (!list_empty(&splice)) {
3948 		btrfs_inode = list_first_entry(&splice, struct btrfs_inode,
3949 					       delalloc_inodes);
3950 
3951 		list_del_init(&btrfs_inode->delalloc_inodes);
3952 		clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
3953 			  &btrfs_inode->runtime_flags);
3954 		spin_unlock(&root->delalloc_lock);
3955 
3956 		btrfs_invalidate_inodes(btrfs_inode->root);
3957 
3958 		spin_lock(&root->delalloc_lock);
3959 	}
3960 
3961 	spin_unlock(&root->delalloc_lock);
3962 }
3963 
3964 static void btrfs_destroy_all_delalloc_inodes(struct btrfs_fs_info *fs_info)
3965 {
3966 	struct btrfs_root *root;
3967 	struct list_head splice;
3968 
3969 	INIT_LIST_HEAD(&splice);
3970 
3971 	spin_lock(&fs_info->delalloc_root_lock);
3972 	list_splice_init(&fs_info->delalloc_roots, &splice);
3973 	while (!list_empty(&splice)) {
3974 		root = list_first_entry(&splice, struct btrfs_root,
3975 					 delalloc_root);
3976 		list_del_init(&root->delalloc_root);
3977 		root = btrfs_grab_fs_root(root);
3978 		BUG_ON(!root);
3979 		spin_unlock(&fs_info->delalloc_root_lock);
3980 
3981 		btrfs_destroy_delalloc_inodes(root);
3982 		btrfs_put_fs_root(root);
3983 
3984 		spin_lock(&fs_info->delalloc_root_lock);
3985 	}
3986 	spin_unlock(&fs_info->delalloc_root_lock);
3987 }
3988 
3989 static int btrfs_destroy_marked_extents(struct btrfs_root *root,
3990 					struct extent_io_tree *dirty_pages,
3991 					int mark)
3992 {
3993 	int ret;
3994 	struct extent_buffer *eb;
3995 	u64 start = 0;
3996 	u64 end;
3997 
3998 	while (1) {
3999 		ret = find_first_extent_bit(dirty_pages, start, &start, &end,
4000 					    mark, NULL);
4001 		if (ret)
4002 			break;
4003 
4004 		clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
4005 		while (start <= end) {
4006 			eb = btrfs_find_tree_block(root, start,
4007 						   root->leafsize);
4008 			start += root->leafsize;
4009 			if (!eb)
4010 				continue;
4011 			wait_on_extent_buffer_writeback(eb);
4012 
4013 			if (test_and_clear_bit(EXTENT_BUFFER_DIRTY,
4014 					       &eb->bflags))
4015 				clear_extent_buffer_dirty(eb);
4016 			free_extent_buffer_stale(eb);
4017 		}
4018 	}
4019 
4020 	return ret;
4021 }
4022 
4023 static int btrfs_destroy_pinned_extent(struct btrfs_root *root,
4024 				       struct extent_io_tree *pinned_extents)
4025 {
4026 	struct extent_io_tree *unpin;
4027 	u64 start;
4028 	u64 end;
4029 	int ret;
4030 	bool loop = true;
4031 
4032 	unpin = pinned_extents;
4033 again:
4034 	while (1) {
4035 		ret = find_first_extent_bit(unpin, 0, &start, &end,
4036 					    EXTENT_DIRTY, NULL);
4037 		if (ret)
4038 			break;
4039 
4040 		/* opt_discard */
4041 		if (btrfs_test_opt(root, DISCARD))
4042 			ret = btrfs_error_discard_extent(root, start,
4043 							 end + 1 - start,
4044 							 NULL);
4045 
4046 		clear_extent_dirty(unpin, start, end, GFP_NOFS);
4047 		btrfs_error_unpin_extent_range(root, start, end);
4048 		cond_resched();
4049 	}
4050 
4051 	if (loop) {
4052 		if (unpin == &root->fs_info->freed_extents[0])
4053 			unpin = &root->fs_info->freed_extents[1];
4054 		else
4055 			unpin = &root->fs_info->freed_extents[0];
4056 		loop = false;
4057 		goto again;
4058 	}
4059 
4060 	return 0;
4061 }
4062 
4063 void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
4064 				   struct btrfs_root *root)
4065 {
4066 	btrfs_destroy_delayed_refs(cur_trans, root);
4067 
4068 	cur_trans->state = TRANS_STATE_COMMIT_START;
4069 	wake_up(&root->fs_info->transaction_blocked_wait);
4070 
4071 	cur_trans->state = TRANS_STATE_UNBLOCKED;
4072 	wake_up(&root->fs_info->transaction_wait);
4073 
4074 	btrfs_destroy_delayed_inodes(root);
4075 	btrfs_assert_delayed_root_empty(root);
4076 
4077 	btrfs_destroy_marked_extents(root, &cur_trans->dirty_pages,
4078 				     EXTENT_DIRTY);
4079 	btrfs_destroy_pinned_extent(root,
4080 				    root->fs_info->pinned_extents);
4081 
4082 	cur_trans->state =TRANS_STATE_COMPLETED;
4083 	wake_up(&cur_trans->commit_wait);
4084 
4085 	/*
4086 	memset(cur_trans, 0, sizeof(*cur_trans));
4087 	kmem_cache_free(btrfs_transaction_cachep, cur_trans);
4088 	*/
4089 }
4090 
4091 static int btrfs_cleanup_transaction(struct btrfs_root *root)
4092 {
4093 	struct btrfs_transaction *t;
4094 
4095 	mutex_lock(&root->fs_info->transaction_kthread_mutex);
4096 
4097 	spin_lock(&root->fs_info->trans_lock);
4098 	while (!list_empty(&root->fs_info->trans_list)) {
4099 		t = list_first_entry(&root->fs_info->trans_list,
4100 				     struct btrfs_transaction, list);
4101 		if (t->state >= TRANS_STATE_COMMIT_START) {
4102 			atomic_inc(&t->use_count);
4103 			spin_unlock(&root->fs_info->trans_lock);
4104 			btrfs_wait_for_commit(root, t->transid);
4105 			btrfs_put_transaction(t);
4106 			spin_lock(&root->fs_info->trans_lock);
4107 			continue;
4108 		}
4109 		if (t == root->fs_info->running_transaction) {
4110 			t->state = TRANS_STATE_COMMIT_DOING;
4111 			spin_unlock(&root->fs_info->trans_lock);
4112 			/*
4113 			 * We wait for 0 num_writers since we don't hold a trans
4114 			 * handle open currently for this transaction.
4115 			 */
4116 			wait_event(t->writer_wait,
4117 				   atomic_read(&t->num_writers) == 0);
4118 		} else {
4119 			spin_unlock(&root->fs_info->trans_lock);
4120 		}
4121 		btrfs_cleanup_one_transaction(t, root);
4122 
4123 		spin_lock(&root->fs_info->trans_lock);
4124 		if (t == root->fs_info->running_transaction)
4125 			root->fs_info->running_transaction = NULL;
4126 		list_del_init(&t->list);
4127 		spin_unlock(&root->fs_info->trans_lock);
4128 
4129 		btrfs_put_transaction(t);
4130 		trace_btrfs_transaction_commit(root);
4131 		spin_lock(&root->fs_info->trans_lock);
4132 	}
4133 	spin_unlock(&root->fs_info->trans_lock);
4134 	btrfs_destroy_all_ordered_extents(root->fs_info);
4135 	btrfs_destroy_delayed_inodes(root);
4136 	btrfs_assert_delayed_root_empty(root);
4137 	btrfs_destroy_pinned_extent(root, root->fs_info->pinned_extents);
4138 	btrfs_destroy_all_delalloc_inodes(root->fs_info);
4139 	mutex_unlock(&root->fs_info->transaction_kthread_mutex);
4140 
4141 	return 0;
4142 }
4143 
4144 static struct extent_io_ops btree_extent_io_ops = {
4145 	.readpage_end_io_hook = btree_readpage_end_io_hook,
4146 	.readpage_io_failed_hook = btree_io_failed_hook,
4147 	.submit_bio_hook = btree_submit_bio_hook,
4148 	/* note we're sharing with inode.c for the merge bio hook */
4149 	.merge_bio_hook = btrfs_merge_bio_hook,
4150 };
4151