1 /*
2  * Copyright (C) 2012 Red Hat, Inc.
3  *
4  * This file is released under the GPL.
5  */
6 
7 #include "dm-cache-metadata.h"
8 
9 #include "persistent-data/dm-array.h"
10 #include "persistent-data/dm-bitset.h"
11 #include "persistent-data/dm-space-map.h"
12 #include "persistent-data/dm-space-map-disk.h"
13 #include "persistent-data/dm-transaction-manager.h"
14 
15 #include <linux/device-mapper.h>
16 #include <linux/refcount.h>
17 
18 /*----------------------------------------------------------------*/
19 
20 #define DM_MSG_PREFIX   "cache metadata"
21 
22 #define CACHE_SUPERBLOCK_MAGIC 06142003
23 #define CACHE_SUPERBLOCK_LOCATION 0
24 
25 /*
26  * defines a range of metadata versions that this module can handle.
27  */
28 #define MIN_CACHE_VERSION 1
29 #define MAX_CACHE_VERSION 2
30 
31 /*
32  *  3 for btree insert +
33  *  2 for btree lookup used within space map
34  */
35 #define CACHE_MAX_CONCURRENT_LOCKS 5
36 #define SPACE_MAP_ROOT_SIZE 128
37 
38 enum superblock_flag_bits {
39 	/* for spotting crashes that would invalidate the dirty bitset */
40 	CLEAN_SHUTDOWN,
41 	/* metadata must be checked using the tools */
42 	NEEDS_CHECK,
43 };
44 
45 /*
46  * Each mapping from cache block -> origin block carries a set of flags.
47  */
48 enum mapping_bits {
49 	/*
50 	 * A valid mapping.  Because we're using an array we clear this
51 	 * flag for an non existant mapping.
52 	 */
53 	M_VALID = 1,
54 
55 	/*
56 	 * The data on the cache is different from that on the origin.
57 	 * This flag is only used by metadata format 1.
58 	 */
59 	M_DIRTY = 2
60 };
61 
62 struct cache_disk_superblock {
63 	__le32 csum;
64 	__le32 flags;
65 	__le64 blocknr;
66 
67 	__u8 uuid[16];
68 	__le64 magic;
69 	__le32 version;
70 
71 	__u8 policy_name[CACHE_POLICY_NAME_SIZE];
72 	__le32 policy_hint_size;
73 
74 	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
75 	__le64 mapping_root;
76 	__le64 hint_root;
77 
78 	__le64 discard_root;
79 	__le64 discard_block_size;
80 	__le64 discard_nr_blocks;
81 
82 	__le32 data_block_size;
83 	__le32 metadata_block_size;
84 	__le32 cache_blocks;
85 
86 	__le32 compat_flags;
87 	__le32 compat_ro_flags;
88 	__le32 incompat_flags;
89 
90 	__le32 read_hits;
91 	__le32 read_misses;
92 	__le32 write_hits;
93 	__le32 write_misses;
94 
95 	__le32 policy_version[CACHE_POLICY_VERSION_SIZE];
96 
97 	/*
98 	 * Metadata format 2 fields.
99 	 */
100 	__le64 dirty_root;
101 } __packed;
102 
103 struct dm_cache_metadata {
104 	refcount_t ref_count;
105 	struct list_head list;
106 
107 	unsigned version;
108 	struct block_device *bdev;
109 	struct dm_block_manager *bm;
110 	struct dm_space_map *metadata_sm;
111 	struct dm_transaction_manager *tm;
112 
113 	struct dm_array_info info;
114 	struct dm_array_info hint_info;
115 	struct dm_disk_bitset discard_info;
116 
117 	struct rw_semaphore root_lock;
118 	unsigned long flags;
119 	dm_block_t root;
120 	dm_block_t hint_root;
121 	dm_block_t discard_root;
122 
123 	sector_t discard_block_size;
124 	dm_dblock_t discard_nr_blocks;
125 
126 	sector_t data_block_size;
127 	dm_cblock_t cache_blocks;
128 	bool changed:1;
129 	bool clean_when_opened:1;
130 
131 	char policy_name[CACHE_POLICY_NAME_SIZE];
132 	unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
133 	size_t policy_hint_size;
134 	struct dm_cache_statistics stats;
135 
136 	/*
137 	 * Reading the space map root can fail, so we read it into this
138 	 * buffer before the superblock is locked and updated.
139 	 */
140 	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
141 
142 	/*
143 	 * Set if a transaction has to be aborted but the attempt to roll
144 	 * back to the previous (good) transaction failed.  The only
145 	 * metadata operation permissible in this state is the closing of
146 	 * the device.
147 	 */
148 	bool fail_io:1;
149 
150 	/*
151 	 * Metadata format 2 fields.
152 	 */
153 	dm_block_t dirty_root;
154 	struct dm_disk_bitset dirty_info;
155 
156 	/*
157 	 * These structures are used when loading metadata.  They're too
158 	 * big to put on the stack.
159 	 */
160 	struct dm_array_cursor mapping_cursor;
161 	struct dm_array_cursor hint_cursor;
162 	struct dm_bitset_cursor dirty_cursor;
163 };
164 
165 /*-------------------------------------------------------------------
166  * superblock validator
167  *-----------------------------------------------------------------*/
168 
169 #define SUPERBLOCK_CSUM_XOR 9031977
170 
sb_prepare_for_write(struct dm_block_validator * v,struct dm_block * b,size_t sb_block_size)171 static void sb_prepare_for_write(struct dm_block_validator *v,
172 				 struct dm_block *b,
173 				 size_t sb_block_size)
174 {
175 	struct cache_disk_superblock *disk_super = dm_block_data(b);
176 
177 	disk_super->blocknr = cpu_to_le64(dm_block_location(b));
178 	disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
179 						      sb_block_size - sizeof(__le32),
180 						      SUPERBLOCK_CSUM_XOR));
181 }
182 
check_metadata_version(struct cache_disk_superblock * disk_super)183 static int check_metadata_version(struct cache_disk_superblock *disk_super)
184 {
185 	uint32_t metadata_version = le32_to_cpu(disk_super->version);
186 
187 	if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
188 		DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
189 		      metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
190 		return -EINVAL;
191 	}
192 
193 	return 0;
194 }
195 
sb_check(struct dm_block_validator * v,struct dm_block * b,size_t sb_block_size)196 static int sb_check(struct dm_block_validator *v,
197 		    struct dm_block *b,
198 		    size_t sb_block_size)
199 {
200 	struct cache_disk_superblock *disk_super = dm_block_data(b);
201 	__le32 csum_le;
202 
203 	if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
204 		DMERR("sb_check failed: blocknr %llu: wanted %llu",
205 		      le64_to_cpu(disk_super->blocknr),
206 		      (unsigned long long)dm_block_location(b));
207 		return -ENOTBLK;
208 	}
209 
210 	if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
211 		DMERR("sb_check failed: magic %llu: wanted %llu",
212 		      le64_to_cpu(disk_super->magic),
213 		      (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
214 		return -EILSEQ;
215 	}
216 
217 	csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
218 					     sb_block_size - sizeof(__le32),
219 					     SUPERBLOCK_CSUM_XOR));
220 	if (csum_le != disk_super->csum) {
221 		DMERR("sb_check failed: csum %u: wanted %u",
222 		      le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
223 		return -EILSEQ;
224 	}
225 
226 	return check_metadata_version(disk_super);
227 }
228 
229 static struct dm_block_validator sb_validator = {
230 	.name = "superblock",
231 	.prepare_for_write = sb_prepare_for_write,
232 	.check = sb_check
233 };
234 
235 /*----------------------------------------------------------------*/
236 
superblock_read_lock(struct dm_cache_metadata * cmd,struct dm_block ** sblock)237 static int superblock_read_lock(struct dm_cache_metadata *cmd,
238 				struct dm_block **sblock)
239 {
240 	return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
241 			       &sb_validator, sblock);
242 }
243 
superblock_lock_zero(struct dm_cache_metadata * cmd,struct dm_block ** sblock)244 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
245 				struct dm_block **sblock)
246 {
247 	return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
248 				     &sb_validator, sblock);
249 }
250 
superblock_lock(struct dm_cache_metadata * cmd,struct dm_block ** sblock)251 static int superblock_lock(struct dm_cache_metadata *cmd,
252 			   struct dm_block **sblock)
253 {
254 	return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
255 				&sb_validator, sblock);
256 }
257 
258 /*----------------------------------------------------------------*/
259 
__superblock_all_zeroes(struct dm_block_manager * bm,bool * result)260 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
261 {
262 	int r;
263 	unsigned i;
264 	struct dm_block *b;
265 	__le64 *data_le, zero = cpu_to_le64(0);
266 	unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
267 
268 	/*
269 	 * We can't use a validator here - it may be all zeroes.
270 	 */
271 	r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
272 	if (r)
273 		return r;
274 
275 	data_le = dm_block_data(b);
276 	*result = true;
277 	for (i = 0; i < sb_block_size; i++) {
278 		if (data_le[i] != zero) {
279 			*result = false;
280 			break;
281 		}
282 	}
283 
284 	dm_bm_unlock(b);
285 
286 	return 0;
287 }
288 
__setup_mapping_info(struct dm_cache_metadata * cmd)289 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
290 {
291 	struct dm_btree_value_type vt;
292 
293 	vt.context = NULL;
294 	vt.size = sizeof(__le64);
295 	vt.inc = NULL;
296 	vt.dec = NULL;
297 	vt.equal = NULL;
298 	dm_array_info_init(&cmd->info, cmd->tm, &vt);
299 
300 	if (cmd->policy_hint_size) {
301 		vt.size = sizeof(__le32);
302 		dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
303 	}
304 }
305 
__save_sm_root(struct dm_cache_metadata * cmd)306 static int __save_sm_root(struct dm_cache_metadata *cmd)
307 {
308 	int r;
309 	size_t metadata_len;
310 
311 	r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
312 	if (r < 0)
313 		return r;
314 
315 	return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
316 			       metadata_len);
317 }
318 
__copy_sm_root(struct dm_cache_metadata * cmd,struct cache_disk_superblock * disk_super)319 static void __copy_sm_root(struct dm_cache_metadata *cmd,
320 			   struct cache_disk_superblock *disk_super)
321 {
322 	memcpy(&disk_super->metadata_space_map_root,
323 	       &cmd->metadata_space_map_root,
324 	       sizeof(cmd->metadata_space_map_root));
325 }
326 
separate_dirty_bits(struct dm_cache_metadata * cmd)327 static bool separate_dirty_bits(struct dm_cache_metadata *cmd)
328 {
329 	return cmd->version >= 2;
330 }
331 
__write_initial_superblock(struct dm_cache_metadata * cmd)332 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
333 {
334 	int r;
335 	struct dm_block *sblock;
336 	struct cache_disk_superblock *disk_super;
337 	sector_t bdev_size = bdev_nr_sectors(cmd->bdev);
338 
339 	/* FIXME: see if we can lose the max sectors limit */
340 	if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
341 		bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
342 
343 	r = dm_tm_pre_commit(cmd->tm);
344 	if (r < 0)
345 		return r;
346 
347 	/*
348 	 * dm_sm_copy_root() can fail.  So we need to do it before we start
349 	 * updating the superblock.
350 	 */
351 	r = __save_sm_root(cmd);
352 	if (r)
353 		return r;
354 
355 	r = superblock_lock_zero(cmd, &sblock);
356 	if (r)
357 		return r;
358 
359 	disk_super = dm_block_data(sblock);
360 	disk_super->flags = 0;
361 	memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
362 	disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
363 	disk_super->version = cpu_to_le32(cmd->version);
364 	memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
365 	memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
366 	disk_super->policy_hint_size = cpu_to_le32(0);
367 
368 	__copy_sm_root(cmd, disk_super);
369 
370 	disk_super->mapping_root = cpu_to_le64(cmd->root);
371 	disk_super->hint_root = cpu_to_le64(cmd->hint_root);
372 	disk_super->discard_root = cpu_to_le64(cmd->discard_root);
373 	disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
374 	disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
375 	disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
376 	disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
377 	disk_super->cache_blocks = cpu_to_le32(0);
378 
379 	disk_super->read_hits = cpu_to_le32(0);
380 	disk_super->read_misses = cpu_to_le32(0);
381 	disk_super->write_hits = cpu_to_le32(0);
382 	disk_super->write_misses = cpu_to_le32(0);
383 
384 	if (separate_dirty_bits(cmd))
385 		disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
386 
387 	return dm_tm_commit(cmd->tm, sblock);
388 }
389 
__format_metadata(struct dm_cache_metadata * cmd)390 static int __format_metadata(struct dm_cache_metadata *cmd)
391 {
392 	int r;
393 
394 	r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
395 				 &cmd->tm, &cmd->metadata_sm);
396 	if (r < 0) {
397 		DMERR("tm_create_with_sm failed");
398 		return r;
399 	}
400 
401 	__setup_mapping_info(cmd);
402 
403 	r = dm_array_empty(&cmd->info, &cmd->root);
404 	if (r < 0)
405 		goto bad;
406 
407 	if (separate_dirty_bits(cmd)) {
408 		dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
409 		r = dm_bitset_empty(&cmd->dirty_info, &cmd->dirty_root);
410 		if (r < 0)
411 			goto bad;
412 	}
413 
414 	dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
415 	r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
416 	if (r < 0)
417 		goto bad;
418 
419 	cmd->discard_block_size = 0;
420 	cmd->discard_nr_blocks = 0;
421 
422 	r = __write_initial_superblock(cmd);
423 	if (r)
424 		goto bad;
425 
426 	cmd->clean_when_opened = true;
427 	return 0;
428 
429 bad:
430 	dm_tm_destroy(cmd->tm);
431 	dm_sm_destroy(cmd->metadata_sm);
432 
433 	return r;
434 }
435 
__check_incompat_features(struct cache_disk_superblock * disk_super,struct dm_cache_metadata * cmd)436 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
437 				     struct dm_cache_metadata *cmd)
438 {
439 	uint32_t incompat_flags, features;
440 
441 	incompat_flags = le32_to_cpu(disk_super->incompat_flags);
442 	features = incompat_flags & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
443 	if (features) {
444 		DMERR("could not access metadata due to unsupported optional features (%lx).",
445 		      (unsigned long)features);
446 		return -EINVAL;
447 	}
448 
449 	/*
450 	 * Check for read-only metadata to skip the following RDWR checks.
451 	 */
452 	if (bdev_read_only(cmd->bdev))
453 		return 0;
454 
455 	features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
456 	if (features) {
457 		DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
458 		      (unsigned long)features);
459 		return -EINVAL;
460 	}
461 
462 	return 0;
463 }
464 
__open_metadata(struct dm_cache_metadata * cmd)465 static int __open_metadata(struct dm_cache_metadata *cmd)
466 {
467 	int r;
468 	struct dm_block *sblock;
469 	struct cache_disk_superblock *disk_super;
470 	unsigned long sb_flags;
471 
472 	r = superblock_read_lock(cmd, &sblock);
473 	if (r < 0) {
474 		DMERR("couldn't read lock superblock");
475 		return r;
476 	}
477 
478 	disk_super = dm_block_data(sblock);
479 
480 	/* Verify the data block size hasn't changed */
481 	if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
482 		DMERR("changing the data block size (from %u to %llu) is not supported",
483 		      le32_to_cpu(disk_super->data_block_size),
484 		      (unsigned long long)cmd->data_block_size);
485 		r = -EINVAL;
486 		goto bad;
487 	}
488 
489 	r = __check_incompat_features(disk_super, cmd);
490 	if (r < 0)
491 		goto bad;
492 
493 	r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
494 			       disk_super->metadata_space_map_root,
495 			       sizeof(disk_super->metadata_space_map_root),
496 			       &cmd->tm, &cmd->metadata_sm);
497 	if (r < 0) {
498 		DMERR("tm_open_with_sm failed");
499 		goto bad;
500 	}
501 
502 	__setup_mapping_info(cmd);
503 	dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
504 	dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
505 	sb_flags = le32_to_cpu(disk_super->flags);
506 	cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
507 	dm_bm_unlock(sblock);
508 
509 	return 0;
510 
511 bad:
512 	dm_bm_unlock(sblock);
513 	return r;
514 }
515 
__open_or_format_metadata(struct dm_cache_metadata * cmd,bool format_device)516 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
517 				     bool format_device)
518 {
519 	int r;
520 	bool unformatted = false;
521 
522 	r = __superblock_all_zeroes(cmd->bm, &unformatted);
523 	if (r)
524 		return r;
525 
526 	if (unformatted)
527 		return format_device ? __format_metadata(cmd) : -EPERM;
528 
529 	return __open_metadata(cmd);
530 }
531 
__create_persistent_data_objects(struct dm_cache_metadata * cmd,bool may_format_device)532 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
533 					    bool may_format_device)
534 {
535 	int r;
536 	cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
537 					  CACHE_MAX_CONCURRENT_LOCKS);
538 	if (IS_ERR(cmd->bm)) {
539 		DMERR("could not create block manager");
540 		r = PTR_ERR(cmd->bm);
541 		cmd->bm = NULL;
542 		return r;
543 	}
544 
545 	r = __open_or_format_metadata(cmd, may_format_device);
546 	if (r) {
547 		dm_block_manager_destroy(cmd->bm);
548 		cmd->bm = NULL;
549 	}
550 
551 	return r;
552 }
553 
__destroy_persistent_data_objects(struct dm_cache_metadata * cmd,bool destroy_bm)554 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd,
555 					      bool destroy_bm)
556 {
557 	dm_sm_destroy(cmd->metadata_sm);
558 	dm_tm_destroy(cmd->tm);
559 	if (destroy_bm)
560 		dm_block_manager_destroy(cmd->bm);
561 }
562 
563 typedef unsigned long (*flags_mutator)(unsigned long);
564 
update_flags(struct cache_disk_superblock * disk_super,flags_mutator mutator)565 static void update_flags(struct cache_disk_superblock *disk_super,
566 			 flags_mutator mutator)
567 {
568 	uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
569 	disk_super->flags = cpu_to_le32(sb_flags);
570 }
571 
set_clean_shutdown(unsigned long flags)572 static unsigned long set_clean_shutdown(unsigned long flags)
573 {
574 	set_bit(CLEAN_SHUTDOWN, &flags);
575 	return flags;
576 }
577 
clear_clean_shutdown(unsigned long flags)578 static unsigned long clear_clean_shutdown(unsigned long flags)
579 {
580 	clear_bit(CLEAN_SHUTDOWN, &flags);
581 	return flags;
582 }
583 
read_superblock_fields(struct dm_cache_metadata * cmd,struct cache_disk_superblock * disk_super)584 static void read_superblock_fields(struct dm_cache_metadata *cmd,
585 				   struct cache_disk_superblock *disk_super)
586 {
587 	cmd->version = le32_to_cpu(disk_super->version);
588 	cmd->flags = le32_to_cpu(disk_super->flags);
589 	cmd->root = le64_to_cpu(disk_super->mapping_root);
590 	cmd->hint_root = le64_to_cpu(disk_super->hint_root);
591 	cmd->discard_root = le64_to_cpu(disk_super->discard_root);
592 	cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
593 	cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
594 	cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
595 	cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
596 	strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
597 	cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
598 	cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
599 	cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
600 	cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
601 
602 	cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
603 	cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
604 	cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
605 	cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
606 
607 	if (separate_dirty_bits(cmd))
608 		cmd->dirty_root = le64_to_cpu(disk_super->dirty_root);
609 
610 	cmd->changed = false;
611 }
612 
613 /*
614  * The mutator updates the superblock flags.
615  */
__begin_transaction_flags(struct dm_cache_metadata * cmd,flags_mutator mutator)616 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
617 				     flags_mutator mutator)
618 {
619 	int r;
620 	struct cache_disk_superblock *disk_super;
621 	struct dm_block *sblock;
622 
623 	r = superblock_lock(cmd, &sblock);
624 	if (r)
625 		return r;
626 
627 	disk_super = dm_block_data(sblock);
628 	update_flags(disk_super, mutator);
629 	read_superblock_fields(cmd, disk_super);
630 	dm_bm_unlock(sblock);
631 
632 	return dm_bm_flush(cmd->bm);
633 }
634 
__begin_transaction(struct dm_cache_metadata * cmd)635 static int __begin_transaction(struct dm_cache_metadata *cmd)
636 {
637 	int r;
638 	struct cache_disk_superblock *disk_super;
639 	struct dm_block *sblock;
640 
641 	/*
642 	 * We re-read the superblock every time.  Shouldn't need to do this
643 	 * really.
644 	 */
645 	r = superblock_read_lock(cmd, &sblock);
646 	if (r)
647 		return r;
648 
649 	disk_super = dm_block_data(sblock);
650 	read_superblock_fields(cmd, disk_super);
651 	dm_bm_unlock(sblock);
652 
653 	return 0;
654 }
655 
__commit_transaction(struct dm_cache_metadata * cmd,flags_mutator mutator)656 static int __commit_transaction(struct dm_cache_metadata *cmd,
657 				flags_mutator mutator)
658 {
659 	int r;
660 	struct cache_disk_superblock *disk_super;
661 	struct dm_block *sblock;
662 
663 	/*
664 	 * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
665 	 */
666 	BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
667 
668 	if (separate_dirty_bits(cmd)) {
669 		r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root,
670 				    &cmd->dirty_root);
671 		if (r)
672 			return r;
673 	}
674 
675 	r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
676 			    &cmd->discard_root);
677 	if (r)
678 		return r;
679 
680 	r = dm_tm_pre_commit(cmd->tm);
681 	if (r < 0)
682 		return r;
683 
684 	r = __save_sm_root(cmd);
685 	if (r)
686 		return r;
687 
688 	r = superblock_lock(cmd, &sblock);
689 	if (r)
690 		return r;
691 
692 	disk_super = dm_block_data(sblock);
693 
694 	disk_super->flags = cpu_to_le32(cmd->flags);
695 	if (mutator)
696 		update_flags(disk_super, mutator);
697 
698 	disk_super->mapping_root = cpu_to_le64(cmd->root);
699 	if (separate_dirty_bits(cmd))
700 		disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
701 	disk_super->hint_root = cpu_to_le64(cmd->hint_root);
702 	disk_super->discard_root = cpu_to_le64(cmd->discard_root);
703 	disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
704 	disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
705 	disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
706 	strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
707 	disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
708 	disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
709 	disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
710 	disk_super->policy_hint_size = cpu_to_le32(cmd->policy_hint_size);
711 
712 	disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
713 	disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
714 	disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
715 	disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
716 	__copy_sm_root(cmd, disk_super);
717 
718 	return dm_tm_commit(cmd->tm, sblock);
719 }
720 
721 /*----------------------------------------------------------------*/
722 
723 /*
724  * The mappings are held in a dm-array that has 64-bit values stored in
725  * little-endian format.  The index is the cblock, the high 48bits of the
726  * value are the oblock and the low 16 bit the flags.
727  */
728 #define FLAGS_MASK ((1 << 16) - 1)
729 
pack_value(dm_oblock_t block,unsigned flags)730 static __le64 pack_value(dm_oblock_t block, unsigned flags)
731 {
732 	uint64_t value = from_oblock(block);
733 	value <<= 16;
734 	value = value | (flags & FLAGS_MASK);
735 	return cpu_to_le64(value);
736 }
737 
unpack_value(__le64 value_le,dm_oblock_t * block,unsigned * flags)738 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
739 {
740 	uint64_t value = le64_to_cpu(value_le);
741 	uint64_t b = value >> 16;
742 	*block = to_oblock(b);
743 	*flags = value & FLAGS_MASK;
744 }
745 
746 /*----------------------------------------------------------------*/
747 
metadata_open(struct block_device * bdev,sector_t data_block_size,bool may_format_device,size_t policy_hint_size,unsigned metadata_version)748 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
749 					       sector_t data_block_size,
750 					       bool may_format_device,
751 					       size_t policy_hint_size,
752 					       unsigned metadata_version)
753 {
754 	int r;
755 	struct dm_cache_metadata *cmd;
756 
757 	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
758 	if (!cmd) {
759 		DMERR("could not allocate metadata struct");
760 		return ERR_PTR(-ENOMEM);
761 	}
762 
763 	cmd->version = metadata_version;
764 	refcount_set(&cmd->ref_count, 1);
765 	init_rwsem(&cmd->root_lock);
766 	cmd->bdev = bdev;
767 	cmd->data_block_size = data_block_size;
768 	cmd->cache_blocks = 0;
769 	cmd->policy_hint_size = policy_hint_size;
770 	cmd->changed = true;
771 	cmd->fail_io = false;
772 
773 	r = __create_persistent_data_objects(cmd, may_format_device);
774 	if (r) {
775 		kfree(cmd);
776 		return ERR_PTR(r);
777 	}
778 
779 	r = __begin_transaction_flags(cmd, clear_clean_shutdown);
780 	if (r < 0) {
781 		dm_cache_metadata_close(cmd);
782 		return ERR_PTR(r);
783 	}
784 
785 	return cmd;
786 }
787 
788 /*
789  * We keep a little list of ref counted metadata objects to prevent two
790  * different target instances creating separate bufio instances.  This is
791  * an issue if a table is reloaded before the suspend.
792  */
793 static DEFINE_MUTEX(table_lock);
794 static LIST_HEAD(table);
795 
lookup(struct block_device * bdev)796 static struct dm_cache_metadata *lookup(struct block_device *bdev)
797 {
798 	struct dm_cache_metadata *cmd;
799 
800 	list_for_each_entry(cmd, &table, list)
801 		if (cmd->bdev == bdev) {
802 			refcount_inc(&cmd->ref_count);
803 			return cmd;
804 		}
805 
806 	return NULL;
807 }
808 
lookup_or_open(struct block_device * bdev,sector_t data_block_size,bool may_format_device,size_t policy_hint_size,unsigned metadata_version)809 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
810 						sector_t data_block_size,
811 						bool may_format_device,
812 						size_t policy_hint_size,
813 						unsigned metadata_version)
814 {
815 	struct dm_cache_metadata *cmd, *cmd2;
816 
817 	mutex_lock(&table_lock);
818 	cmd = lookup(bdev);
819 	mutex_unlock(&table_lock);
820 
821 	if (cmd)
822 		return cmd;
823 
824 	cmd = metadata_open(bdev, data_block_size, may_format_device,
825 			    policy_hint_size, metadata_version);
826 	if (!IS_ERR(cmd)) {
827 		mutex_lock(&table_lock);
828 		cmd2 = lookup(bdev);
829 		if (cmd2) {
830 			mutex_unlock(&table_lock);
831 			__destroy_persistent_data_objects(cmd, true);
832 			kfree(cmd);
833 			return cmd2;
834 		}
835 		list_add(&cmd->list, &table);
836 		mutex_unlock(&table_lock);
837 	}
838 
839 	return cmd;
840 }
841 
same_params(struct dm_cache_metadata * cmd,sector_t data_block_size)842 static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
843 {
844 	if (cmd->data_block_size != data_block_size) {
845 		DMERR("data_block_size (%llu) different from that in metadata (%llu)",
846 		      (unsigned long long) data_block_size,
847 		      (unsigned long long) cmd->data_block_size);
848 		return false;
849 	}
850 
851 	return true;
852 }
853 
dm_cache_metadata_open(struct block_device * bdev,sector_t data_block_size,bool may_format_device,size_t policy_hint_size,unsigned metadata_version)854 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
855 						 sector_t data_block_size,
856 						 bool may_format_device,
857 						 size_t policy_hint_size,
858 						 unsigned metadata_version)
859 {
860 	struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device,
861 						       policy_hint_size, metadata_version);
862 
863 	if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
864 		dm_cache_metadata_close(cmd);
865 		return ERR_PTR(-EINVAL);
866 	}
867 
868 	return cmd;
869 }
870 
dm_cache_metadata_close(struct dm_cache_metadata * cmd)871 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
872 {
873 	if (refcount_dec_and_test(&cmd->ref_count)) {
874 		mutex_lock(&table_lock);
875 		list_del(&cmd->list);
876 		mutex_unlock(&table_lock);
877 
878 		if (!cmd->fail_io)
879 			__destroy_persistent_data_objects(cmd, true);
880 		kfree(cmd);
881 	}
882 }
883 
884 /*
885  * Checks that the given cache block is either unmapped or clean.
886  */
block_clean_combined_dirty(struct dm_cache_metadata * cmd,dm_cblock_t b,bool * result)887 static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b,
888 				      bool *result)
889 {
890 	int r;
891 	__le64 value;
892 	dm_oblock_t ob;
893 	unsigned flags;
894 
895 	r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
896 	if (r)
897 		return r;
898 
899 	unpack_value(value, &ob, &flags);
900 	*result = !((flags & M_VALID) && (flags & M_DIRTY));
901 
902 	return 0;
903 }
904 
blocks_are_clean_combined_dirty(struct dm_cache_metadata * cmd,dm_cblock_t begin,dm_cblock_t end,bool * result)905 static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd,
906 					   dm_cblock_t begin, dm_cblock_t end,
907 					   bool *result)
908 {
909 	int r;
910 	*result = true;
911 
912 	while (begin != end) {
913 		r = block_clean_combined_dirty(cmd, begin, result);
914 		if (r) {
915 			DMERR("block_clean_combined_dirty failed");
916 			return r;
917 		}
918 
919 		if (!*result) {
920 			DMERR("cache block %llu is dirty",
921 			      (unsigned long long) from_cblock(begin));
922 			return 0;
923 		}
924 
925 		begin = to_cblock(from_cblock(begin) + 1);
926 	}
927 
928 	return 0;
929 }
930 
blocks_are_clean_separate_dirty(struct dm_cache_metadata * cmd,dm_cblock_t begin,dm_cblock_t end,bool * result)931 static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd,
932 					   dm_cblock_t begin, dm_cblock_t end,
933 					   bool *result)
934 {
935 	int r;
936 	bool dirty_flag;
937 	*result = true;
938 
939 	if (from_cblock(cmd->cache_blocks) == 0)
940 		/* Nothing to do */
941 		return 0;
942 
943 	r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
944 				   from_cblock(cmd->cache_blocks), &cmd->dirty_cursor);
945 	if (r) {
946 		DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__);
947 		return r;
948 	}
949 
950 	r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin));
951 	if (r) {
952 		DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__);
953 		dm_bitset_cursor_end(&cmd->dirty_cursor);
954 		return r;
955 	}
956 
957 	while (begin != end) {
958 		/*
959 		 * We assume that unmapped blocks have their dirty bit
960 		 * cleared.
961 		 */
962 		dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor);
963 		if (dirty_flag) {
964 			DMERR("%s: cache block %llu is dirty", __func__,
965 			      (unsigned long long) from_cblock(begin));
966 			dm_bitset_cursor_end(&cmd->dirty_cursor);
967 			*result = false;
968 			return 0;
969 		}
970 
971 		begin = to_cblock(from_cblock(begin) + 1);
972 		if (begin == end)
973 			break;
974 
975 		r = dm_bitset_cursor_next(&cmd->dirty_cursor);
976 		if (r) {
977 			DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__);
978 			dm_bitset_cursor_end(&cmd->dirty_cursor);
979 			return r;
980 		}
981 	}
982 
983 	dm_bitset_cursor_end(&cmd->dirty_cursor);
984 
985 	return 0;
986 }
987 
blocks_are_unmapped_or_clean(struct dm_cache_metadata * cmd,dm_cblock_t begin,dm_cblock_t end,bool * result)988 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
989 					dm_cblock_t begin, dm_cblock_t end,
990 					bool *result)
991 {
992 	if (separate_dirty_bits(cmd))
993 		return blocks_are_clean_separate_dirty(cmd, begin, end, result);
994 	else
995 		return blocks_are_clean_combined_dirty(cmd, begin, end, result);
996 }
997 
cmd_write_lock(struct dm_cache_metadata * cmd)998 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
999 {
1000 	down_write(&cmd->root_lock);
1001 	if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
1002 		up_write(&cmd->root_lock);
1003 		return false;
1004 	}
1005 	return true;
1006 }
1007 
1008 #define WRITE_LOCK(cmd)				\
1009 	do {					\
1010 		if (!cmd_write_lock((cmd)))	\
1011 			return -EINVAL;		\
1012 	} while(0)
1013 
1014 #define WRITE_LOCK_VOID(cmd)			\
1015 	do {					\
1016 		if (!cmd_write_lock((cmd)))	\
1017 			return;			\
1018 	} while(0)
1019 
1020 #define WRITE_UNLOCK(cmd) \
1021 	up_write(&(cmd)->root_lock)
1022 
cmd_read_lock(struct dm_cache_metadata * cmd)1023 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
1024 {
1025 	down_read(&cmd->root_lock);
1026 	if (cmd->fail_io) {
1027 		up_read(&cmd->root_lock);
1028 		return false;
1029 	}
1030 	return true;
1031 }
1032 
1033 #define READ_LOCK(cmd)				\
1034 	do {					\
1035 		if (!cmd_read_lock((cmd)))	\
1036 			return -EINVAL;		\
1037 	} while(0)
1038 
1039 #define READ_LOCK_VOID(cmd)			\
1040 	do {					\
1041 		if (!cmd_read_lock((cmd)))	\
1042 			return;			\
1043 	} while(0)
1044 
1045 #define READ_UNLOCK(cmd) \
1046 	up_read(&(cmd)->root_lock)
1047 
dm_cache_resize(struct dm_cache_metadata * cmd,dm_cblock_t new_cache_size)1048 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
1049 {
1050 	int r;
1051 	bool clean;
1052 	__le64 null_mapping = pack_value(0, 0);
1053 
1054 	WRITE_LOCK(cmd);
1055 	__dm_bless_for_disk(&null_mapping);
1056 
1057 	if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
1058 		r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
1059 		if (r) {
1060 			__dm_unbless_for_disk(&null_mapping);
1061 			goto out;
1062 		}
1063 
1064 		if (!clean) {
1065 			DMERR("unable to shrink cache due to dirty blocks");
1066 			r = -EINVAL;
1067 			__dm_unbless_for_disk(&null_mapping);
1068 			goto out;
1069 		}
1070 	}
1071 
1072 	r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
1073 			    from_cblock(new_cache_size),
1074 			    &null_mapping, &cmd->root);
1075 	if (r)
1076 		goto out;
1077 
1078 	if (separate_dirty_bits(cmd)) {
1079 		r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root,
1080 				     from_cblock(cmd->cache_blocks), from_cblock(new_cache_size),
1081 				     false, &cmd->dirty_root);
1082 		if (r)
1083 			goto out;
1084 	}
1085 
1086 	cmd->cache_blocks = new_cache_size;
1087 	cmd->changed = true;
1088 
1089 out:
1090 	WRITE_UNLOCK(cmd);
1091 
1092 	return r;
1093 }
1094 
dm_cache_discard_bitset_resize(struct dm_cache_metadata * cmd,sector_t discard_block_size,dm_dblock_t new_nr_entries)1095 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
1096 				   sector_t discard_block_size,
1097 				   dm_dblock_t new_nr_entries)
1098 {
1099 	int r;
1100 
1101 	WRITE_LOCK(cmd);
1102 	r = dm_bitset_resize(&cmd->discard_info,
1103 			     cmd->discard_root,
1104 			     from_dblock(cmd->discard_nr_blocks),
1105 			     from_dblock(new_nr_entries),
1106 			     false, &cmd->discard_root);
1107 	if (!r) {
1108 		cmd->discard_block_size = discard_block_size;
1109 		cmd->discard_nr_blocks = new_nr_entries;
1110 	}
1111 
1112 	cmd->changed = true;
1113 	WRITE_UNLOCK(cmd);
1114 
1115 	return r;
1116 }
1117 
__set_discard(struct dm_cache_metadata * cmd,dm_dblock_t b)1118 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1119 {
1120 	return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
1121 				 from_dblock(b), &cmd->discard_root);
1122 }
1123 
__clear_discard(struct dm_cache_metadata * cmd,dm_dblock_t b)1124 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1125 {
1126 	return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
1127 				   from_dblock(b), &cmd->discard_root);
1128 }
1129 
__discard(struct dm_cache_metadata * cmd,dm_dblock_t dblock,bool discard)1130 static int __discard(struct dm_cache_metadata *cmd,
1131 		     dm_dblock_t dblock, bool discard)
1132 {
1133 	int r;
1134 
1135 	r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
1136 	if (r)
1137 		return r;
1138 
1139 	cmd->changed = true;
1140 	return 0;
1141 }
1142 
dm_cache_set_discard(struct dm_cache_metadata * cmd,dm_dblock_t dblock,bool discard)1143 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
1144 			 dm_dblock_t dblock, bool discard)
1145 {
1146 	int r;
1147 
1148 	WRITE_LOCK(cmd);
1149 	r = __discard(cmd, dblock, discard);
1150 	WRITE_UNLOCK(cmd);
1151 
1152 	return r;
1153 }
1154 
__load_discards(struct dm_cache_metadata * cmd,load_discard_fn fn,void * context)1155 static int __load_discards(struct dm_cache_metadata *cmd,
1156 			   load_discard_fn fn, void *context)
1157 {
1158 	int r = 0;
1159 	uint32_t b;
1160 	struct dm_bitset_cursor c;
1161 
1162 	if (from_dblock(cmd->discard_nr_blocks) == 0)
1163 		/* nothing to do */
1164 		return 0;
1165 
1166 	if (cmd->clean_when_opened) {
1167 		r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root);
1168 		if (r)
1169 			return r;
1170 
1171 		r = dm_bitset_cursor_begin(&cmd->discard_info, cmd->discard_root,
1172 					   from_dblock(cmd->discard_nr_blocks), &c);
1173 		if (r)
1174 			return r;
1175 
1176 		for (b = 0; ; b++) {
1177 			r = fn(context, cmd->discard_block_size, to_dblock(b),
1178 			       dm_bitset_cursor_get_value(&c));
1179 			if (r)
1180 				break;
1181 
1182 			if (b >= (from_dblock(cmd->discard_nr_blocks) - 1))
1183 				break;
1184 
1185 			r = dm_bitset_cursor_next(&c);
1186 			if (r)
1187 				break;
1188 		}
1189 
1190 		dm_bitset_cursor_end(&c);
1191 
1192 	} else {
1193 		for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1194 			r = fn(context, cmd->discard_block_size, to_dblock(b), false);
1195 			if (r)
1196 				return r;
1197 		}
1198 	}
1199 
1200 	return r;
1201 }
1202 
dm_cache_load_discards(struct dm_cache_metadata * cmd,load_discard_fn fn,void * context)1203 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1204 			   load_discard_fn fn, void *context)
1205 {
1206 	int r;
1207 
1208 	READ_LOCK(cmd);
1209 	r = __load_discards(cmd, fn, context);
1210 	READ_UNLOCK(cmd);
1211 
1212 	return r;
1213 }
1214 
dm_cache_size(struct dm_cache_metadata * cmd,dm_cblock_t * result)1215 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1216 {
1217 	READ_LOCK(cmd);
1218 	*result = cmd->cache_blocks;
1219 	READ_UNLOCK(cmd);
1220 
1221 	return 0;
1222 }
1223 
__remove(struct dm_cache_metadata * cmd,dm_cblock_t cblock)1224 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1225 {
1226 	int r;
1227 	__le64 value = pack_value(0, 0);
1228 
1229 	__dm_bless_for_disk(&value);
1230 	r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1231 			       &value, &cmd->root);
1232 	if (r)
1233 		return r;
1234 
1235 	cmd->changed = true;
1236 	return 0;
1237 }
1238 
dm_cache_remove_mapping(struct dm_cache_metadata * cmd,dm_cblock_t cblock)1239 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1240 {
1241 	int r;
1242 
1243 	WRITE_LOCK(cmd);
1244 	r = __remove(cmd, cblock);
1245 	WRITE_UNLOCK(cmd);
1246 
1247 	return r;
1248 }
1249 
__insert(struct dm_cache_metadata * cmd,dm_cblock_t cblock,dm_oblock_t oblock)1250 static int __insert(struct dm_cache_metadata *cmd,
1251 		    dm_cblock_t cblock, dm_oblock_t oblock)
1252 {
1253 	int r;
1254 	__le64 value = pack_value(oblock, M_VALID);
1255 	__dm_bless_for_disk(&value);
1256 
1257 	r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1258 			       &value, &cmd->root);
1259 	if (r)
1260 		return r;
1261 
1262 	cmd->changed = true;
1263 	return 0;
1264 }
1265 
dm_cache_insert_mapping(struct dm_cache_metadata * cmd,dm_cblock_t cblock,dm_oblock_t oblock)1266 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1267 			    dm_cblock_t cblock, dm_oblock_t oblock)
1268 {
1269 	int r;
1270 
1271 	WRITE_LOCK(cmd);
1272 	r = __insert(cmd, cblock, oblock);
1273 	WRITE_UNLOCK(cmd);
1274 
1275 	return r;
1276 }
1277 
1278 struct thunk {
1279 	load_mapping_fn fn;
1280 	void *context;
1281 
1282 	struct dm_cache_metadata *cmd;
1283 	bool respect_dirty_flags;
1284 	bool hints_valid;
1285 };
1286 
policy_unchanged(struct dm_cache_metadata * cmd,struct dm_cache_policy * policy)1287 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1288 			     struct dm_cache_policy *policy)
1289 {
1290 	const char *policy_name = dm_cache_policy_get_name(policy);
1291 	const unsigned *policy_version = dm_cache_policy_get_version(policy);
1292 	size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1293 
1294 	/*
1295 	 * Ensure policy names match.
1296 	 */
1297 	if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1298 		return false;
1299 
1300 	/*
1301 	 * Ensure policy major versions match.
1302 	 */
1303 	if (cmd->policy_version[0] != policy_version[0])
1304 		return false;
1305 
1306 	/*
1307 	 * Ensure policy hint sizes match.
1308 	 */
1309 	if (cmd->policy_hint_size != policy_hint_size)
1310 		return false;
1311 
1312 	return true;
1313 }
1314 
hints_array_initialized(struct dm_cache_metadata * cmd)1315 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1316 {
1317 	return cmd->hint_root && cmd->policy_hint_size;
1318 }
1319 
hints_array_available(struct dm_cache_metadata * cmd,struct dm_cache_policy * policy)1320 static bool hints_array_available(struct dm_cache_metadata *cmd,
1321 				  struct dm_cache_policy *policy)
1322 {
1323 	return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1324 		hints_array_initialized(cmd);
1325 }
1326 
__load_mapping_v1(struct dm_cache_metadata * cmd,uint64_t cb,bool hints_valid,struct dm_array_cursor * mapping_cursor,struct dm_array_cursor * hint_cursor,load_mapping_fn fn,void * context)1327 static int __load_mapping_v1(struct dm_cache_metadata *cmd,
1328 			     uint64_t cb, bool hints_valid,
1329 			     struct dm_array_cursor *mapping_cursor,
1330 			     struct dm_array_cursor *hint_cursor,
1331 			     load_mapping_fn fn, void *context)
1332 {
1333 	int r = 0;
1334 
1335 	__le64 mapping;
1336 	__le32 hint = 0;
1337 
1338 	__le64 *mapping_value_le;
1339 	__le32 *hint_value_le;
1340 
1341 	dm_oblock_t oblock;
1342 	unsigned flags;
1343 	bool dirty = true;
1344 
1345 	dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1346 	memcpy(&mapping, mapping_value_le, sizeof(mapping));
1347 	unpack_value(mapping, &oblock, &flags);
1348 
1349 	if (flags & M_VALID) {
1350 		if (hints_valid) {
1351 			dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1352 			memcpy(&hint, hint_value_le, sizeof(hint));
1353 		}
1354 		if (cmd->clean_when_opened)
1355 			dirty = flags & M_DIRTY;
1356 
1357 		r = fn(context, oblock, to_cblock(cb), dirty,
1358 		       le32_to_cpu(hint), hints_valid);
1359 		if (r) {
1360 			DMERR("policy couldn't load cache block %llu",
1361 			      (unsigned long long) from_cblock(to_cblock(cb)));
1362 		}
1363 	}
1364 
1365 	return r;
1366 }
1367 
__load_mapping_v2(struct dm_cache_metadata * cmd,uint64_t cb,bool hints_valid,struct dm_array_cursor * mapping_cursor,struct dm_array_cursor * hint_cursor,struct dm_bitset_cursor * dirty_cursor,load_mapping_fn fn,void * context)1368 static int __load_mapping_v2(struct dm_cache_metadata *cmd,
1369 			     uint64_t cb, bool hints_valid,
1370 			     struct dm_array_cursor *mapping_cursor,
1371 			     struct dm_array_cursor *hint_cursor,
1372 			     struct dm_bitset_cursor *dirty_cursor,
1373 			     load_mapping_fn fn, void *context)
1374 {
1375 	int r = 0;
1376 
1377 	__le64 mapping;
1378 	__le32 hint = 0;
1379 
1380 	__le64 *mapping_value_le;
1381 	__le32 *hint_value_le;
1382 
1383 	dm_oblock_t oblock;
1384 	unsigned flags;
1385 	bool dirty = true;
1386 
1387 	dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1388 	memcpy(&mapping, mapping_value_le, sizeof(mapping));
1389 	unpack_value(mapping, &oblock, &flags);
1390 
1391 	if (flags & M_VALID) {
1392 		if (hints_valid) {
1393 			dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1394 			memcpy(&hint, hint_value_le, sizeof(hint));
1395 		}
1396 		if (cmd->clean_when_opened)
1397 			dirty = dm_bitset_cursor_get_value(dirty_cursor);
1398 
1399 		r = fn(context, oblock, to_cblock(cb), dirty,
1400 		       le32_to_cpu(hint), hints_valid);
1401 		if (r) {
1402 			DMERR("policy couldn't load cache block %llu",
1403 			      (unsigned long long) from_cblock(to_cblock(cb)));
1404 		}
1405 	}
1406 
1407 	return r;
1408 }
1409 
__load_mappings(struct dm_cache_metadata * cmd,struct dm_cache_policy * policy,load_mapping_fn fn,void * context)1410 static int __load_mappings(struct dm_cache_metadata *cmd,
1411 			   struct dm_cache_policy *policy,
1412 			   load_mapping_fn fn, void *context)
1413 {
1414 	int r;
1415 	uint64_t cb;
1416 
1417 	bool hints_valid = hints_array_available(cmd, policy);
1418 
1419 	if (from_cblock(cmd->cache_blocks) == 0)
1420 		/* Nothing to do */
1421 		return 0;
1422 
1423 	r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1424 	if (r)
1425 		return r;
1426 
1427 	if (hints_valid) {
1428 		r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1429 		if (r) {
1430 			dm_array_cursor_end(&cmd->mapping_cursor);
1431 			return r;
1432 		}
1433 	}
1434 
1435 	if (separate_dirty_bits(cmd)) {
1436 		r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
1437 					   from_cblock(cmd->cache_blocks),
1438 					   &cmd->dirty_cursor);
1439 		if (r) {
1440 			dm_array_cursor_end(&cmd->hint_cursor);
1441 			dm_array_cursor_end(&cmd->mapping_cursor);
1442 			return r;
1443 		}
1444 	}
1445 
1446 	for (cb = 0; ; cb++) {
1447 		if (separate_dirty_bits(cmd))
1448 			r = __load_mapping_v2(cmd, cb, hints_valid,
1449 					      &cmd->mapping_cursor,
1450 					      &cmd->hint_cursor,
1451 					      &cmd->dirty_cursor,
1452 					      fn, context);
1453 		else
1454 			r = __load_mapping_v1(cmd, cb, hints_valid,
1455 					      &cmd->mapping_cursor, &cmd->hint_cursor,
1456 					      fn, context);
1457 		if (r)
1458 			goto out;
1459 
1460 		/*
1461 		 * We need to break out before we move the cursors.
1462 		 */
1463 		if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1464 			break;
1465 
1466 		r = dm_array_cursor_next(&cmd->mapping_cursor);
1467 		if (r) {
1468 			DMERR("dm_array_cursor_next for mapping failed");
1469 			goto out;
1470 		}
1471 
1472 		if (hints_valid) {
1473 			r = dm_array_cursor_next(&cmd->hint_cursor);
1474 			if (r) {
1475 				dm_array_cursor_end(&cmd->hint_cursor);
1476 				hints_valid = false;
1477 			}
1478 		}
1479 
1480 		if (separate_dirty_bits(cmd)) {
1481 			r = dm_bitset_cursor_next(&cmd->dirty_cursor);
1482 			if (r) {
1483 				DMERR("dm_bitset_cursor_next for dirty failed");
1484 				goto out;
1485 			}
1486 		}
1487 	}
1488 out:
1489 	dm_array_cursor_end(&cmd->mapping_cursor);
1490 	if (hints_valid)
1491 		dm_array_cursor_end(&cmd->hint_cursor);
1492 
1493 	if (separate_dirty_bits(cmd))
1494 		dm_bitset_cursor_end(&cmd->dirty_cursor);
1495 
1496 	return r;
1497 }
1498 
dm_cache_load_mappings(struct dm_cache_metadata * cmd,struct dm_cache_policy * policy,load_mapping_fn fn,void * context)1499 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1500 			   struct dm_cache_policy *policy,
1501 			   load_mapping_fn fn, void *context)
1502 {
1503 	int r;
1504 
1505 	READ_LOCK(cmd);
1506 	r = __load_mappings(cmd, policy, fn, context);
1507 	READ_UNLOCK(cmd);
1508 
1509 	return r;
1510 }
1511 
__dump_mapping(void * context,uint64_t cblock,void * leaf)1512 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1513 {
1514 	__le64 value;
1515 	dm_oblock_t oblock;
1516 	unsigned flags;
1517 
1518 	memcpy(&value, leaf, sizeof(value));
1519 	unpack_value(value, &oblock, &flags);
1520 
1521 	return 0;
1522 }
1523 
__dump_mappings(struct dm_cache_metadata * cmd)1524 static int __dump_mappings(struct dm_cache_metadata *cmd)
1525 {
1526 	return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1527 }
1528 
dm_cache_dump(struct dm_cache_metadata * cmd)1529 void dm_cache_dump(struct dm_cache_metadata *cmd)
1530 {
1531 	READ_LOCK_VOID(cmd);
1532 	__dump_mappings(cmd);
1533 	READ_UNLOCK(cmd);
1534 }
1535 
dm_cache_changed_this_transaction(struct dm_cache_metadata * cmd)1536 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1537 {
1538 	int r;
1539 
1540 	READ_LOCK(cmd);
1541 	r = cmd->changed;
1542 	READ_UNLOCK(cmd);
1543 
1544 	return r;
1545 }
1546 
__dirty(struct dm_cache_metadata * cmd,dm_cblock_t cblock,bool dirty)1547 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1548 {
1549 	int r;
1550 	unsigned flags;
1551 	dm_oblock_t oblock;
1552 	__le64 value;
1553 
1554 	r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1555 	if (r)
1556 		return r;
1557 
1558 	unpack_value(value, &oblock, &flags);
1559 
1560 	if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1561 		/* nothing to be done */
1562 		return 0;
1563 
1564 	value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1565 	__dm_bless_for_disk(&value);
1566 
1567 	r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1568 			       &value, &cmd->root);
1569 	if (r)
1570 		return r;
1571 
1572 	cmd->changed = true;
1573 	return 0;
1574 
1575 }
1576 
__set_dirty_bits_v1(struct dm_cache_metadata * cmd,unsigned nr_bits,unsigned long * bits)1577 static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1578 {
1579 	int r;
1580 	unsigned i;
1581 	for (i = 0; i < nr_bits; i++) {
1582 		r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
1583 		if (r)
1584 			return r;
1585 	}
1586 
1587 	return 0;
1588 }
1589 
is_dirty_callback(uint32_t index,bool * value,void * context)1590 static int is_dirty_callback(uint32_t index, bool *value, void *context)
1591 {
1592 	unsigned long *bits = context;
1593 	*value = test_bit(index, bits);
1594 	return 0;
1595 }
1596 
__set_dirty_bits_v2(struct dm_cache_metadata * cmd,unsigned nr_bits,unsigned long * bits)1597 static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1598 {
1599 	int r = 0;
1600 
1601 	/* nr_bits is really just a sanity check */
1602 	if (nr_bits != from_cblock(cmd->cache_blocks)) {
1603 		DMERR("dirty bitset is wrong size");
1604 		return -EINVAL;
1605 	}
1606 
1607 	r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root);
1608 	if (r)
1609 		return r;
1610 
1611 	cmd->changed = true;
1612 	return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits);
1613 }
1614 
dm_cache_set_dirty_bits(struct dm_cache_metadata * cmd,unsigned nr_bits,unsigned long * bits)1615 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
1616 			    unsigned nr_bits,
1617 			    unsigned long *bits)
1618 {
1619 	int r;
1620 
1621 	WRITE_LOCK(cmd);
1622 	if (separate_dirty_bits(cmd))
1623 		r = __set_dirty_bits_v2(cmd, nr_bits, bits);
1624 	else
1625 		r = __set_dirty_bits_v1(cmd, nr_bits, bits);
1626 	WRITE_UNLOCK(cmd);
1627 
1628 	return r;
1629 }
1630 
dm_cache_metadata_get_stats(struct dm_cache_metadata * cmd,struct dm_cache_statistics * stats)1631 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1632 				 struct dm_cache_statistics *stats)
1633 {
1634 	READ_LOCK_VOID(cmd);
1635 	*stats = cmd->stats;
1636 	READ_UNLOCK(cmd);
1637 }
1638 
dm_cache_metadata_set_stats(struct dm_cache_metadata * cmd,struct dm_cache_statistics * stats)1639 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1640 				 struct dm_cache_statistics *stats)
1641 {
1642 	WRITE_LOCK_VOID(cmd);
1643 	cmd->stats = *stats;
1644 	WRITE_UNLOCK(cmd);
1645 }
1646 
dm_cache_commit(struct dm_cache_metadata * cmd,bool clean_shutdown)1647 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1648 {
1649 	int r = -EINVAL;
1650 	flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1651 				 clear_clean_shutdown);
1652 
1653 	WRITE_LOCK(cmd);
1654 	if (cmd->fail_io)
1655 		goto out;
1656 
1657 	r = __commit_transaction(cmd, mutator);
1658 	if (r)
1659 		goto out;
1660 
1661 	r = __begin_transaction(cmd);
1662 out:
1663 	WRITE_UNLOCK(cmd);
1664 	return r;
1665 }
1666 
dm_cache_get_free_metadata_block_count(struct dm_cache_metadata * cmd,dm_block_t * result)1667 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1668 					   dm_block_t *result)
1669 {
1670 	int r = -EINVAL;
1671 
1672 	READ_LOCK(cmd);
1673 	if (!cmd->fail_io)
1674 		r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1675 	READ_UNLOCK(cmd);
1676 
1677 	return r;
1678 }
1679 
dm_cache_get_metadata_dev_size(struct dm_cache_metadata * cmd,dm_block_t * result)1680 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1681 				   dm_block_t *result)
1682 {
1683 	int r = -EINVAL;
1684 
1685 	READ_LOCK(cmd);
1686 	if (!cmd->fail_io)
1687 		r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1688 	READ_UNLOCK(cmd);
1689 
1690 	return r;
1691 }
1692 
1693 /*----------------------------------------------------------------*/
1694 
get_hint(uint32_t index,void * value_le,void * context)1695 static int get_hint(uint32_t index, void *value_le, void *context)
1696 {
1697 	uint32_t value;
1698 	struct dm_cache_policy *policy = context;
1699 
1700 	value = policy_get_hint(policy, to_cblock(index));
1701 	*((__le32 *) value_le) = cpu_to_le32(value);
1702 
1703 	return 0;
1704 }
1705 
1706 /*
1707  * It's quicker to always delete the hint array, and recreate with
1708  * dm_array_new().
1709  */
write_hints(struct dm_cache_metadata * cmd,struct dm_cache_policy * policy)1710 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1711 {
1712 	int r;
1713 	size_t hint_size;
1714 	const char *policy_name = dm_cache_policy_get_name(policy);
1715 	const unsigned *policy_version = dm_cache_policy_get_version(policy);
1716 
1717 	if (!policy_name[0] ||
1718 	    (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1719 		return -EINVAL;
1720 
1721 	strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1722 	memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1723 
1724 	hint_size = dm_cache_policy_get_hint_size(policy);
1725 	if (!hint_size)
1726 		return 0; /* short-circuit hints initialization */
1727 	cmd->policy_hint_size = hint_size;
1728 
1729 	if (cmd->hint_root) {
1730 		r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1731 		if (r)
1732 			return r;
1733 	}
1734 
1735 	return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1736 			    from_cblock(cmd->cache_blocks),
1737 			    get_hint, policy);
1738 }
1739 
dm_cache_write_hints(struct dm_cache_metadata * cmd,struct dm_cache_policy * policy)1740 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1741 {
1742 	int r;
1743 
1744 	WRITE_LOCK(cmd);
1745 	r = write_hints(cmd, policy);
1746 	WRITE_UNLOCK(cmd);
1747 
1748 	return r;
1749 }
1750 
dm_cache_metadata_all_clean(struct dm_cache_metadata * cmd,bool * result)1751 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1752 {
1753 	int r;
1754 
1755 	READ_LOCK(cmd);
1756 	r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1757 	READ_UNLOCK(cmd);
1758 
1759 	return r;
1760 }
1761 
dm_cache_metadata_set_read_only(struct dm_cache_metadata * cmd)1762 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1763 {
1764 	WRITE_LOCK_VOID(cmd);
1765 	dm_bm_set_read_only(cmd->bm);
1766 	WRITE_UNLOCK(cmd);
1767 }
1768 
dm_cache_metadata_set_read_write(struct dm_cache_metadata * cmd)1769 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1770 {
1771 	WRITE_LOCK_VOID(cmd);
1772 	dm_bm_set_read_write(cmd->bm);
1773 	WRITE_UNLOCK(cmd);
1774 }
1775 
dm_cache_metadata_set_needs_check(struct dm_cache_metadata * cmd)1776 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1777 {
1778 	int r;
1779 	struct dm_block *sblock;
1780 	struct cache_disk_superblock *disk_super;
1781 
1782 	WRITE_LOCK(cmd);
1783 	set_bit(NEEDS_CHECK, &cmd->flags);
1784 
1785 	r = superblock_lock(cmd, &sblock);
1786 	if (r) {
1787 		DMERR("couldn't read superblock");
1788 		goto out;
1789 	}
1790 
1791 	disk_super = dm_block_data(sblock);
1792 	disk_super->flags = cpu_to_le32(cmd->flags);
1793 
1794 	dm_bm_unlock(sblock);
1795 
1796 out:
1797 	WRITE_UNLOCK(cmd);
1798 	return r;
1799 }
1800 
dm_cache_metadata_needs_check(struct dm_cache_metadata * cmd,bool * result)1801 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1802 {
1803 	READ_LOCK(cmd);
1804 	*result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1805 	READ_UNLOCK(cmd);
1806 
1807 	return 0;
1808 }
1809 
dm_cache_metadata_abort(struct dm_cache_metadata * cmd)1810 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1811 {
1812 	int r = -EINVAL;
1813 	struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
1814 
1815 	/* fail_io is double-checked with cmd->root_lock held below */
1816 	if (unlikely(cmd->fail_io))
1817 		return r;
1818 
1819 	/*
1820 	 * Replacement block manager (new_bm) is created and old_bm destroyed outside of
1821 	 * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of
1822 	 * shrinker associated with the block manager's bufio client vs cmd root_lock).
1823 	 * - must take shrinker_rwsem without holding cmd->root_lock
1824 	 */
1825 	new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
1826 					 CACHE_MAX_CONCURRENT_LOCKS);
1827 
1828 	WRITE_LOCK(cmd);
1829 	if (cmd->fail_io) {
1830 		WRITE_UNLOCK(cmd);
1831 		goto out;
1832 	}
1833 
1834 	__destroy_persistent_data_objects(cmd, false);
1835 	old_bm = cmd->bm;
1836 	if (IS_ERR(new_bm)) {
1837 		DMERR("could not create block manager during abort");
1838 		cmd->bm = NULL;
1839 		r = PTR_ERR(new_bm);
1840 		goto out_unlock;
1841 	}
1842 
1843 	cmd->bm = new_bm;
1844 	r = __open_or_format_metadata(cmd, false);
1845 	if (r) {
1846 		cmd->bm = NULL;
1847 		goto out_unlock;
1848 	}
1849 	new_bm = NULL;
1850 out_unlock:
1851 	if (r)
1852 		cmd->fail_io = true;
1853 	WRITE_UNLOCK(cmd);
1854 	dm_block_manager_destroy(old_bm);
1855 out:
1856 	if (new_bm && !IS_ERR(new_bm))
1857 		dm_block_manager_destroy(new_bm);
1858 
1859 	return r;
1860 }
1861