GNU Linux-libre 4.19.264-gnu1
[releases.git] / drivers / md / dm-cache-metadata.c
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
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
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
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
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
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
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
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
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
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
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
327 static bool separate_dirty_bits(struct dm_cache_metadata *cmd)
328 {
329         return cmd->version >= 2;
330 }
331
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 = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
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
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
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 (get_disk_ro(cmd->bdev->bd_disk))
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
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
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
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
554 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
555 {
556         dm_sm_destroy(cmd->metadata_sm);
557         dm_tm_destroy(cmd->tm);
558         dm_block_manager_destroy(cmd->bm);
559 }
560
561 typedef unsigned long (*flags_mutator)(unsigned long);
562
563 static void update_flags(struct cache_disk_superblock *disk_super,
564                          flags_mutator mutator)
565 {
566         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
567         disk_super->flags = cpu_to_le32(sb_flags);
568 }
569
570 static unsigned long set_clean_shutdown(unsigned long flags)
571 {
572         set_bit(CLEAN_SHUTDOWN, &flags);
573         return flags;
574 }
575
576 static unsigned long clear_clean_shutdown(unsigned long flags)
577 {
578         clear_bit(CLEAN_SHUTDOWN, &flags);
579         return flags;
580 }
581
582 static void read_superblock_fields(struct dm_cache_metadata *cmd,
583                                    struct cache_disk_superblock *disk_super)
584 {
585         cmd->version = le32_to_cpu(disk_super->version);
586         cmd->flags = le32_to_cpu(disk_super->flags);
587         cmd->root = le64_to_cpu(disk_super->mapping_root);
588         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
589         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
590         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
591         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
592         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
593         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
594         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
595         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
596         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
597         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
598         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
599
600         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
601         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
602         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
603         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
604
605         if (separate_dirty_bits(cmd))
606                 cmd->dirty_root = le64_to_cpu(disk_super->dirty_root);
607
608         cmd->changed = false;
609 }
610
611 /*
612  * The mutator updates the superblock flags.
613  */
614 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
615                                      flags_mutator mutator)
616 {
617         int r;
618         struct cache_disk_superblock *disk_super;
619         struct dm_block *sblock;
620
621         r = superblock_lock(cmd, &sblock);
622         if (r)
623                 return r;
624
625         disk_super = dm_block_data(sblock);
626         update_flags(disk_super, mutator);
627         read_superblock_fields(cmd, disk_super);
628         dm_bm_unlock(sblock);
629
630         return dm_bm_flush(cmd->bm);
631 }
632
633 static int __begin_transaction(struct dm_cache_metadata *cmd)
634 {
635         int r;
636         struct cache_disk_superblock *disk_super;
637         struct dm_block *sblock;
638
639         /*
640          * We re-read the superblock every time.  Shouldn't need to do this
641          * really.
642          */
643         r = superblock_read_lock(cmd, &sblock);
644         if (r)
645                 return r;
646
647         disk_super = dm_block_data(sblock);
648         read_superblock_fields(cmd, disk_super);
649         dm_bm_unlock(sblock);
650
651         return 0;
652 }
653
654 static int __commit_transaction(struct dm_cache_metadata *cmd,
655                                 flags_mutator mutator)
656 {
657         int r;
658         struct cache_disk_superblock *disk_super;
659         struct dm_block *sblock;
660
661         /*
662          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
663          */
664         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
665
666         if (separate_dirty_bits(cmd)) {
667                 r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root,
668                                     &cmd->dirty_root);
669                 if (r)
670                         return r;
671         }
672
673         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
674                             &cmd->discard_root);
675         if (r)
676                 return r;
677
678         r = dm_tm_pre_commit(cmd->tm);
679         if (r < 0)
680                 return r;
681
682         r = __save_sm_root(cmd);
683         if (r)
684                 return r;
685
686         r = superblock_lock(cmd, &sblock);
687         if (r)
688                 return r;
689
690         disk_super = dm_block_data(sblock);
691
692         disk_super->flags = cpu_to_le32(cmd->flags);
693         if (mutator)
694                 update_flags(disk_super, mutator);
695
696         disk_super->mapping_root = cpu_to_le64(cmd->root);
697         if (separate_dirty_bits(cmd))
698                 disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
699         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
700         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
701         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
702         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
703         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
704         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
705         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
706         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
707         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
708         disk_super->policy_hint_size = cpu_to_le32(cmd->policy_hint_size);
709
710         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
711         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
712         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
713         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
714         __copy_sm_root(cmd, disk_super);
715
716         return dm_tm_commit(cmd->tm, sblock);
717 }
718
719 /*----------------------------------------------------------------*/
720
721 /*
722  * The mappings are held in a dm-array that has 64-bit values stored in
723  * little-endian format.  The index is the cblock, the high 48bits of the
724  * value are the oblock and the low 16 bit the flags.
725  */
726 #define FLAGS_MASK ((1 << 16) - 1)
727
728 static __le64 pack_value(dm_oblock_t block, unsigned flags)
729 {
730         uint64_t value = from_oblock(block);
731         value <<= 16;
732         value = value | (flags & FLAGS_MASK);
733         return cpu_to_le64(value);
734 }
735
736 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
737 {
738         uint64_t value = le64_to_cpu(value_le);
739         uint64_t b = value >> 16;
740         *block = to_oblock(b);
741         *flags = value & FLAGS_MASK;
742 }
743
744 /*----------------------------------------------------------------*/
745
746 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
747                                                sector_t data_block_size,
748                                                bool may_format_device,
749                                                size_t policy_hint_size,
750                                                unsigned metadata_version)
751 {
752         int r;
753         struct dm_cache_metadata *cmd;
754
755         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
756         if (!cmd) {
757                 DMERR("could not allocate metadata struct");
758                 return ERR_PTR(-ENOMEM);
759         }
760
761         cmd->version = metadata_version;
762         refcount_set(&cmd->ref_count, 1);
763         init_rwsem(&cmd->root_lock);
764         cmd->bdev = bdev;
765         cmd->data_block_size = data_block_size;
766         cmd->cache_blocks = 0;
767         cmd->policy_hint_size = policy_hint_size;
768         cmd->changed = true;
769         cmd->fail_io = false;
770
771         r = __create_persistent_data_objects(cmd, may_format_device);
772         if (r) {
773                 kfree(cmd);
774                 return ERR_PTR(r);
775         }
776
777         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
778         if (r < 0) {
779                 dm_cache_metadata_close(cmd);
780                 return ERR_PTR(r);
781         }
782
783         return cmd;
784 }
785
786 /*
787  * We keep a little list of ref counted metadata objects to prevent two
788  * different target instances creating separate bufio instances.  This is
789  * an issue if a table is reloaded before the suspend.
790  */
791 static DEFINE_MUTEX(table_lock);
792 static LIST_HEAD(table);
793
794 static struct dm_cache_metadata *lookup(struct block_device *bdev)
795 {
796         struct dm_cache_metadata *cmd;
797
798         list_for_each_entry(cmd, &table, list)
799                 if (cmd->bdev == bdev) {
800                         refcount_inc(&cmd->ref_count);
801                         return cmd;
802                 }
803
804         return NULL;
805 }
806
807 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
808                                                 sector_t data_block_size,
809                                                 bool may_format_device,
810                                                 size_t policy_hint_size,
811                                                 unsigned metadata_version)
812 {
813         struct dm_cache_metadata *cmd, *cmd2;
814
815         mutex_lock(&table_lock);
816         cmd = lookup(bdev);
817         mutex_unlock(&table_lock);
818
819         if (cmd)
820                 return cmd;
821
822         cmd = metadata_open(bdev, data_block_size, may_format_device,
823                             policy_hint_size, metadata_version);
824         if (!IS_ERR(cmd)) {
825                 mutex_lock(&table_lock);
826                 cmd2 = lookup(bdev);
827                 if (cmd2) {
828                         mutex_unlock(&table_lock);
829                         __destroy_persistent_data_objects(cmd);
830                         kfree(cmd);
831                         return cmd2;
832                 }
833                 list_add(&cmd->list, &table);
834                 mutex_unlock(&table_lock);
835         }
836
837         return cmd;
838 }
839
840 static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
841 {
842         if (cmd->data_block_size != data_block_size) {
843                 DMERR("data_block_size (%llu) different from that in metadata (%llu)",
844                       (unsigned long long) data_block_size,
845                       (unsigned long long) cmd->data_block_size);
846                 return false;
847         }
848
849         return true;
850 }
851
852 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
853                                                  sector_t data_block_size,
854                                                  bool may_format_device,
855                                                  size_t policy_hint_size,
856                                                  unsigned metadata_version)
857 {
858         struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device,
859                                                        policy_hint_size, metadata_version);
860
861         if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
862                 dm_cache_metadata_close(cmd);
863                 return ERR_PTR(-EINVAL);
864         }
865
866         return cmd;
867 }
868
869 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
870 {
871         if (refcount_dec_and_test(&cmd->ref_count)) {
872                 mutex_lock(&table_lock);
873                 list_del(&cmd->list);
874                 mutex_unlock(&table_lock);
875
876                 if (!cmd->fail_io)
877                         __destroy_persistent_data_objects(cmd);
878                 kfree(cmd);
879         }
880 }
881
882 /*
883  * Checks that the given cache block is either unmapped or clean.
884  */
885 static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b,
886                                       bool *result)
887 {
888         int r;
889         __le64 value;
890         dm_oblock_t ob;
891         unsigned flags;
892
893         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
894         if (r)
895                 return r;
896
897         unpack_value(value, &ob, &flags);
898         *result = !((flags & M_VALID) && (flags & M_DIRTY));
899
900         return 0;
901 }
902
903 static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd,
904                                            dm_cblock_t begin, dm_cblock_t end,
905                                            bool *result)
906 {
907         int r;
908         *result = true;
909
910         while (begin != end) {
911                 r = block_clean_combined_dirty(cmd, begin, result);
912                 if (r) {
913                         DMERR("block_clean_combined_dirty failed");
914                         return r;
915                 }
916
917                 if (!*result) {
918                         DMERR("cache block %llu is dirty",
919                               (unsigned long long) from_cblock(begin));
920                         return 0;
921                 }
922
923                 begin = to_cblock(from_cblock(begin) + 1);
924         }
925
926         return 0;
927 }
928
929 static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd,
930                                            dm_cblock_t begin, dm_cblock_t end,
931                                            bool *result)
932 {
933         int r;
934         bool dirty_flag;
935         *result = true;
936
937         if (from_cblock(cmd->cache_blocks) == 0)
938                 /* Nothing to do */
939                 return 0;
940
941         r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
942                                    from_cblock(cmd->cache_blocks), &cmd->dirty_cursor);
943         if (r) {
944                 DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__);
945                 return r;
946         }
947
948         r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin));
949         if (r) {
950                 DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__);
951                 dm_bitset_cursor_end(&cmd->dirty_cursor);
952                 return r;
953         }
954
955         while (begin != end) {
956                 /*
957                  * We assume that unmapped blocks have their dirty bit
958                  * cleared.
959                  */
960                 dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor);
961                 if (dirty_flag) {
962                         DMERR("%s: cache block %llu is dirty", __func__,
963                               (unsigned long long) from_cblock(begin));
964                         dm_bitset_cursor_end(&cmd->dirty_cursor);
965                         *result = false;
966                         return 0;
967                 }
968
969                 begin = to_cblock(from_cblock(begin) + 1);
970                 if (begin == end)
971                         break;
972
973                 r = dm_bitset_cursor_next(&cmd->dirty_cursor);
974                 if (r) {
975                         DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__);
976                         dm_bitset_cursor_end(&cmd->dirty_cursor);
977                         return r;
978                 }
979         }
980
981         dm_bitset_cursor_end(&cmd->dirty_cursor);
982
983         return 0;
984 }
985
986 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
987                                         dm_cblock_t begin, dm_cblock_t end,
988                                         bool *result)
989 {
990         if (separate_dirty_bits(cmd))
991                 return blocks_are_clean_separate_dirty(cmd, begin, end, result);
992         else
993                 return blocks_are_clean_combined_dirty(cmd, begin, end, result);
994 }
995
996 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
997 {
998         down_write(&cmd->root_lock);
999         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
1000                 up_write(&cmd->root_lock);
1001                 return false;
1002         }
1003         return true;
1004 }
1005
1006 #define WRITE_LOCK(cmd)                         \
1007         do {                                    \
1008                 if (!cmd_write_lock((cmd)))     \
1009                         return -EINVAL;         \
1010         } while(0)
1011
1012 #define WRITE_LOCK_VOID(cmd)                    \
1013         do {                                    \
1014                 if (!cmd_write_lock((cmd)))     \
1015                         return;                 \
1016         } while(0)
1017
1018 #define WRITE_UNLOCK(cmd) \
1019         up_write(&(cmd)->root_lock)
1020
1021 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
1022 {
1023         down_read(&cmd->root_lock);
1024         if (cmd->fail_io) {
1025                 up_read(&cmd->root_lock);
1026                 return false;
1027         }
1028         return true;
1029 }
1030
1031 #define READ_LOCK(cmd)                          \
1032         do {                                    \
1033                 if (!cmd_read_lock((cmd)))      \
1034                         return -EINVAL;         \
1035         } while(0)
1036
1037 #define READ_LOCK_VOID(cmd)                     \
1038         do {                                    \
1039                 if (!cmd_read_lock((cmd)))      \
1040                         return;                 \
1041         } while(0)
1042
1043 #define READ_UNLOCK(cmd) \
1044         up_read(&(cmd)->root_lock)
1045
1046 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
1047 {
1048         int r;
1049         bool clean;
1050         __le64 null_mapping = pack_value(0, 0);
1051
1052         WRITE_LOCK(cmd);
1053         __dm_bless_for_disk(&null_mapping);
1054
1055         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
1056                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
1057                 if (r) {
1058                         __dm_unbless_for_disk(&null_mapping);
1059                         goto out;
1060                 }
1061
1062                 if (!clean) {
1063                         DMERR("unable to shrink cache due to dirty blocks");
1064                         r = -EINVAL;
1065                         __dm_unbless_for_disk(&null_mapping);
1066                         goto out;
1067                 }
1068         }
1069
1070         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
1071                             from_cblock(new_cache_size),
1072                             &null_mapping, &cmd->root);
1073         if (r)
1074                 goto out;
1075
1076         if (separate_dirty_bits(cmd)) {
1077                 r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root,
1078                                      from_cblock(cmd->cache_blocks), from_cblock(new_cache_size),
1079                                      false, &cmd->dirty_root);
1080                 if (r)
1081                         goto out;
1082         }
1083
1084         cmd->cache_blocks = new_cache_size;
1085         cmd->changed = true;
1086
1087 out:
1088         WRITE_UNLOCK(cmd);
1089
1090         return r;
1091 }
1092
1093 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
1094                                    sector_t discard_block_size,
1095                                    dm_dblock_t new_nr_entries)
1096 {
1097         int r;
1098
1099         WRITE_LOCK(cmd);
1100         r = dm_bitset_resize(&cmd->discard_info,
1101                              cmd->discard_root,
1102                              from_dblock(cmd->discard_nr_blocks),
1103                              from_dblock(new_nr_entries),
1104                              false, &cmd->discard_root);
1105         if (!r) {
1106                 cmd->discard_block_size = discard_block_size;
1107                 cmd->discard_nr_blocks = new_nr_entries;
1108         }
1109
1110         cmd->changed = true;
1111         WRITE_UNLOCK(cmd);
1112
1113         return r;
1114 }
1115
1116 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1117 {
1118         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
1119                                  from_dblock(b), &cmd->discard_root);
1120 }
1121
1122 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1123 {
1124         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
1125                                    from_dblock(b), &cmd->discard_root);
1126 }
1127
1128 static int __discard(struct dm_cache_metadata *cmd,
1129                      dm_dblock_t dblock, bool discard)
1130 {
1131         int r;
1132
1133         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
1134         if (r)
1135                 return r;
1136
1137         cmd->changed = true;
1138         return 0;
1139 }
1140
1141 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
1142                          dm_dblock_t dblock, bool discard)
1143 {
1144         int r;
1145
1146         WRITE_LOCK(cmd);
1147         r = __discard(cmd, dblock, discard);
1148         WRITE_UNLOCK(cmd);
1149
1150         return r;
1151 }
1152
1153 static int __load_discards(struct dm_cache_metadata *cmd,
1154                            load_discard_fn fn, void *context)
1155 {
1156         int r = 0;
1157         uint32_t b;
1158         struct dm_bitset_cursor c;
1159
1160         if (from_dblock(cmd->discard_nr_blocks) == 0)
1161                 /* nothing to do */
1162                 return 0;
1163
1164         if (cmd->clean_when_opened) {
1165                 r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root);
1166                 if (r)
1167                         return r;
1168
1169                 r = dm_bitset_cursor_begin(&cmd->discard_info, cmd->discard_root,
1170                                            from_dblock(cmd->discard_nr_blocks), &c);
1171                 if (r)
1172                         return r;
1173
1174                 for (b = 0; ; b++) {
1175                         r = fn(context, cmd->discard_block_size, to_dblock(b),
1176                                dm_bitset_cursor_get_value(&c));
1177                         if (r)
1178                                 break;
1179
1180                         if (b >= (from_dblock(cmd->discard_nr_blocks) - 1))
1181                                 break;
1182
1183                         r = dm_bitset_cursor_next(&c);
1184                         if (r)
1185                                 break;
1186                 }
1187
1188                 dm_bitset_cursor_end(&c);
1189
1190         } else {
1191                 for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1192                         r = fn(context, cmd->discard_block_size, to_dblock(b), false);
1193                         if (r)
1194                                 return r;
1195                 }
1196         }
1197
1198         return r;
1199 }
1200
1201 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1202                            load_discard_fn fn, void *context)
1203 {
1204         int r;
1205
1206         READ_LOCK(cmd);
1207         r = __load_discards(cmd, fn, context);
1208         READ_UNLOCK(cmd);
1209
1210         return r;
1211 }
1212
1213 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1214 {
1215         READ_LOCK(cmd);
1216         *result = cmd->cache_blocks;
1217         READ_UNLOCK(cmd);
1218
1219         return 0;
1220 }
1221
1222 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1223 {
1224         int r;
1225         __le64 value = pack_value(0, 0);
1226
1227         __dm_bless_for_disk(&value);
1228         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1229                                &value, &cmd->root);
1230         if (r)
1231                 return r;
1232
1233         cmd->changed = true;
1234         return 0;
1235 }
1236
1237 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1238 {
1239         int r;
1240
1241         WRITE_LOCK(cmd);
1242         r = __remove(cmd, cblock);
1243         WRITE_UNLOCK(cmd);
1244
1245         return r;
1246 }
1247
1248 static int __insert(struct dm_cache_metadata *cmd,
1249                     dm_cblock_t cblock, dm_oblock_t oblock)
1250 {
1251         int r;
1252         __le64 value = pack_value(oblock, M_VALID);
1253         __dm_bless_for_disk(&value);
1254
1255         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1256                                &value, &cmd->root);
1257         if (r)
1258                 return r;
1259
1260         cmd->changed = true;
1261         return 0;
1262 }
1263
1264 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1265                             dm_cblock_t cblock, dm_oblock_t oblock)
1266 {
1267         int r;
1268
1269         WRITE_LOCK(cmd);
1270         r = __insert(cmd, cblock, oblock);
1271         WRITE_UNLOCK(cmd);
1272
1273         return r;
1274 }
1275
1276 struct thunk {
1277         load_mapping_fn fn;
1278         void *context;
1279
1280         struct dm_cache_metadata *cmd;
1281         bool respect_dirty_flags;
1282         bool hints_valid;
1283 };
1284
1285 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1286                              struct dm_cache_policy *policy)
1287 {
1288         const char *policy_name = dm_cache_policy_get_name(policy);
1289         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1290         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1291
1292         /*
1293          * Ensure policy names match.
1294          */
1295         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1296                 return false;
1297
1298         /*
1299          * Ensure policy major versions match.
1300          */
1301         if (cmd->policy_version[0] != policy_version[0])
1302                 return false;
1303
1304         /*
1305          * Ensure policy hint sizes match.
1306          */
1307         if (cmd->policy_hint_size != policy_hint_size)
1308                 return false;
1309
1310         return true;
1311 }
1312
1313 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1314 {
1315         return cmd->hint_root && cmd->policy_hint_size;
1316 }
1317
1318 static bool hints_array_available(struct dm_cache_metadata *cmd,
1319                                   struct dm_cache_policy *policy)
1320 {
1321         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1322                 hints_array_initialized(cmd);
1323 }
1324
1325 static int __load_mapping_v1(struct dm_cache_metadata *cmd,
1326                              uint64_t cb, bool hints_valid,
1327                              struct dm_array_cursor *mapping_cursor,
1328                              struct dm_array_cursor *hint_cursor,
1329                              load_mapping_fn fn, void *context)
1330 {
1331         int r = 0;
1332
1333         __le64 mapping;
1334         __le32 hint = 0;
1335
1336         __le64 *mapping_value_le;
1337         __le32 *hint_value_le;
1338
1339         dm_oblock_t oblock;
1340         unsigned flags;
1341         bool dirty = true;
1342
1343         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1344         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1345         unpack_value(mapping, &oblock, &flags);
1346
1347         if (flags & M_VALID) {
1348                 if (hints_valid) {
1349                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1350                         memcpy(&hint, hint_value_le, sizeof(hint));
1351                 }
1352                 if (cmd->clean_when_opened)
1353                         dirty = flags & M_DIRTY;
1354
1355                 r = fn(context, oblock, to_cblock(cb), dirty,
1356                        le32_to_cpu(hint), hints_valid);
1357                 if (r) {
1358                         DMERR("policy couldn't load cache block %llu",
1359                               (unsigned long long) from_cblock(to_cblock(cb)));
1360                 }
1361         }
1362
1363         return r;
1364 }
1365
1366 static int __load_mapping_v2(struct dm_cache_metadata *cmd,
1367                              uint64_t cb, bool hints_valid,
1368                              struct dm_array_cursor *mapping_cursor,
1369                              struct dm_array_cursor *hint_cursor,
1370                              struct dm_bitset_cursor *dirty_cursor,
1371                              load_mapping_fn fn, void *context)
1372 {
1373         int r = 0;
1374
1375         __le64 mapping;
1376         __le32 hint = 0;
1377
1378         __le64 *mapping_value_le;
1379         __le32 *hint_value_le;
1380
1381         dm_oblock_t oblock;
1382         unsigned flags;
1383         bool dirty = true;
1384
1385         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1386         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1387         unpack_value(mapping, &oblock, &flags);
1388
1389         if (flags & M_VALID) {
1390                 if (hints_valid) {
1391                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1392                         memcpy(&hint, hint_value_le, sizeof(hint));
1393                 }
1394                 if (cmd->clean_when_opened)
1395                         dirty = dm_bitset_cursor_get_value(dirty_cursor);
1396
1397                 r = fn(context, oblock, to_cblock(cb), dirty,
1398                        le32_to_cpu(hint), hints_valid);
1399                 if (r) {
1400                         DMERR("policy couldn't load cache block %llu",
1401                               (unsigned long long) from_cblock(to_cblock(cb)));
1402                 }
1403         }
1404
1405         return r;
1406 }
1407
1408 static int __load_mappings(struct dm_cache_metadata *cmd,
1409                            struct dm_cache_policy *policy,
1410                            load_mapping_fn fn, void *context)
1411 {
1412         int r;
1413         uint64_t cb;
1414
1415         bool hints_valid = hints_array_available(cmd, policy);
1416
1417         if (from_cblock(cmd->cache_blocks) == 0)
1418                 /* Nothing to do */
1419                 return 0;
1420
1421         r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1422         if (r)
1423                 return r;
1424
1425         if (hints_valid) {
1426                 r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1427                 if (r) {
1428                         dm_array_cursor_end(&cmd->mapping_cursor);
1429                         return r;
1430                 }
1431         }
1432
1433         if (separate_dirty_bits(cmd)) {
1434                 r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
1435                                            from_cblock(cmd->cache_blocks),
1436                                            &cmd->dirty_cursor);
1437                 if (r) {
1438                         dm_array_cursor_end(&cmd->hint_cursor);
1439                         dm_array_cursor_end(&cmd->mapping_cursor);
1440                         return r;
1441                 }
1442         }
1443
1444         for (cb = 0; ; cb++) {
1445                 if (separate_dirty_bits(cmd))
1446                         r = __load_mapping_v2(cmd, cb, hints_valid,
1447                                               &cmd->mapping_cursor,
1448                                               &cmd->hint_cursor,
1449                                               &cmd->dirty_cursor,
1450                                               fn, context);
1451                 else
1452                         r = __load_mapping_v1(cmd, cb, hints_valid,
1453                                               &cmd->mapping_cursor, &cmd->hint_cursor,
1454                                               fn, context);
1455                 if (r)
1456                         goto out;
1457
1458                 /*
1459                  * We need to break out before we move the cursors.
1460                  */
1461                 if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1462                         break;
1463
1464                 r = dm_array_cursor_next(&cmd->mapping_cursor);
1465                 if (r) {
1466                         DMERR("dm_array_cursor_next for mapping failed");
1467                         goto out;
1468                 }
1469
1470                 if (hints_valid) {
1471                         r = dm_array_cursor_next(&cmd->hint_cursor);
1472                         if (r) {
1473                                 dm_array_cursor_end(&cmd->hint_cursor);
1474                                 hints_valid = false;
1475                         }
1476                 }
1477
1478                 if (separate_dirty_bits(cmd)) {
1479                         r = dm_bitset_cursor_next(&cmd->dirty_cursor);
1480                         if (r) {
1481                                 DMERR("dm_bitset_cursor_next for dirty failed");
1482                                 goto out;
1483                         }
1484                 }
1485         }
1486 out:
1487         dm_array_cursor_end(&cmd->mapping_cursor);
1488         if (hints_valid)
1489                 dm_array_cursor_end(&cmd->hint_cursor);
1490
1491         if (separate_dirty_bits(cmd))
1492                 dm_bitset_cursor_end(&cmd->dirty_cursor);
1493
1494         return r;
1495 }
1496
1497 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1498                            struct dm_cache_policy *policy,
1499                            load_mapping_fn fn, void *context)
1500 {
1501         int r;
1502
1503         READ_LOCK(cmd);
1504         r = __load_mappings(cmd, policy, fn, context);
1505         READ_UNLOCK(cmd);
1506
1507         return r;
1508 }
1509
1510 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1511 {
1512         int r = 0;
1513         __le64 value;
1514         dm_oblock_t oblock;
1515         unsigned flags;
1516
1517         memcpy(&value, leaf, sizeof(value));
1518         unpack_value(value, &oblock, &flags);
1519
1520         return r;
1521 }
1522
1523 static int __dump_mappings(struct dm_cache_metadata *cmd)
1524 {
1525         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1526 }
1527
1528 void dm_cache_dump(struct dm_cache_metadata *cmd)
1529 {
1530         READ_LOCK_VOID(cmd);
1531         __dump_mappings(cmd);
1532         READ_UNLOCK(cmd);
1533 }
1534
1535 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1536 {
1537         int r;
1538
1539         READ_LOCK(cmd);
1540         r = cmd->changed;
1541         READ_UNLOCK(cmd);
1542
1543         return r;
1544 }
1545
1546 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1547 {
1548         int r;
1549         unsigned flags;
1550         dm_oblock_t oblock;
1551         __le64 value;
1552
1553         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1554         if (r)
1555                 return r;
1556
1557         unpack_value(value, &oblock, &flags);
1558
1559         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1560                 /* nothing to be done */
1561                 return 0;
1562
1563         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1564         __dm_bless_for_disk(&value);
1565
1566         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1567                                &value, &cmd->root);
1568         if (r)
1569                 return r;
1570
1571         cmd->changed = true;
1572         return 0;
1573
1574 }
1575
1576 static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1577 {
1578         int r;
1579         unsigned i;
1580         for (i = 0; i < nr_bits; i++) {
1581                 r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
1582                 if (r)
1583                         return r;
1584         }
1585
1586         return 0;
1587 }
1588
1589 static int is_dirty_callback(uint32_t index, bool *value, void *context)
1590 {
1591         unsigned long *bits = context;
1592         *value = test_bit(index, bits);
1593         return 0;
1594 }
1595
1596 static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1597 {
1598         int r = 0;
1599
1600         /* nr_bits is really just a sanity check */
1601         if (nr_bits != from_cblock(cmd->cache_blocks)) {
1602                 DMERR("dirty bitset is wrong size");
1603                 return -EINVAL;
1604         }
1605
1606         r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root);
1607         if (r)
1608                 return r;
1609
1610         cmd->changed = true;
1611         return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits);
1612 }
1613
1614 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
1615                             unsigned nr_bits,
1616                             unsigned long *bits)
1617 {
1618         int r;
1619
1620         WRITE_LOCK(cmd);
1621         if (separate_dirty_bits(cmd))
1622                 r = __set_dirty_bits_v2(cmd, nr_bits, bits);
1623         else
1624                 r = __set_dirty_bits_v1(cmd, nr_bits, bits);
1625         WRITE_UNLOCK(cmd);
1626
1627         return r;
1628 }
1629
1630 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1631                                  struct dm_cache_statistics *stats)
1632 {
1633         READ_LOCK_VOID(cmd);
1634         *stats = cmd->stats;
1635         READ_UNLOCK(cmd);
1636 }
1637
1638 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1639                                  struct dm_cache_statistics *stats)
1640 {
1641         WRITE_LOCK_VOID(cmd);
1642         cmd->stats = *stats;
1643         WRITE_UNLOCK(cmd);
1644 }
1645
1646 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1647 {
1648         int r = -EINVAL;
1649         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1650                                  clear_clean_shutdown);
1651
1652         WRITE_LOCK(cmd);
1653         if (cmd->fail_io)
1654                 goto out;
1655
1656         r = __commit_transaction(cmd, mutator);
1657         if (r)
1658                 goto out;
1659
1660         r = __begin_transaction(cmd);
1661 out:
1662         WRITE_UNLOCK(cmd);
1663         return r;
1664 }
1665
1666 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1667                                            dm_block_t *result)
1668 {
1669         int r = -EINVAL;
1670
1671         READ_LOCK(cmd);
1672         if (!cmd->fail_io)
1673                 r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1674         READ_UNLOCK(cmd);
1675
1676         return r;
1677 }
1678
1679 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1680                                    dm_block_t *result)
1681 {
1682         int r = -EINVAL;
1683
1684         READ_LOCK(cmd);
1685         if (!cmd->fail_io)
1686                 r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1687         READ_UNLOCK(cmd);
1688
1689         return r;
1690 }
1691
1692 /*----------------------------------------------------------------*/
1693
1694 static int get_hint(uint32_t index, void *value_le, void *context)
1695 {
1696         uint32_t value;
1697         struct dm_cache_policy *policy = context;
1698
1699         value = policy_get_hint(policy, to_cblock(index));
1700         *((__le32 *) value_le) = cpu_to_le32(value);
1701
1702         return 0;
1703 }
1704
1705 /*
1706  * It's quicker to always delete the hint array, and recreate with
1707  * dm_array_new().
1708  */
1709 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1710 {
1711         int r;
1712         size_t hint_size;
1713         const char *policy_name = dm_cache_policy_get_name(policy);
1714         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1715
1716         if (!policy_name[0] ||
1717             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1718                 return -EINVAL;
1719
1720         strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1721         memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1722
1723         hint_size = dm_cache_policy_get_hint_size(policy);
1724         if (!hint_size)
1725                 return 0; /* short-circuit hints initialization */
1726         cmd->policy_hint_size = hint_size;
1727
1728         if (cmd->hint_root) {
1729                 r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1730                 if (r)
1731                         return r;
1732         }
1733
1734         return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1735                             from_cblock(cmd->cache_blocks),
1736                             get_hint, policy);
1737 }
1738
1739 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1740 {
1741         int r;
1742
1743         WRITE_LOCK(cmd);
1744         r = write_hints(cmd, policy);
1745         WRITE_UNLOCK(cmd);
1746
1747         return r;
1748 }
1749
1750 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1751 {
1752         int r;
1753
1754         READ_LOCK(cmd);
1755         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1756         READ_UNLOCK(cmd);
1757
1758         return r;
1759 }
1760
1761 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1762 {
1763         WRITE_LOCK_VOID(cmd);
1764         dm_bm_set_read_only(cmd->bm);
1765         WRITE_UNLOCK(cmd);
1766 }
1767
1768 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1769 {
1770         WRITE_LOCK_VOID(cmd);
1771         dm_bm_set_read_write(cmd->bm);
1772         WRITE_UNLOCK(cmd);
1773 }
1774
1775 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1776 {
1777         int r;
1778         struct dm_block *sblock;
1779         struct cache_disk_superblock *disk_super;
1780
1781         WRITE_LOCK(cmd);
1782         set_bit(NEEDS_CHECK, &cmd->flags);
1783
1784         r = superblock_lock(cmd, &sblock);
1785         if (r) {
1786                 DMERR("couldn't read superblock");
1787                 goto out;
1788         }
1789
1790         disk_super = dm_block_data(sblock);
1791         disk_super->flags = cpu_to_le32(cmd->flags);
1792
1793         dm_bm_unlock(sblock);
1794
1795 out:
1796         WRITE_UNLOCK(cmd);
1797         return r;
1798 }
1799
1800 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1801 {
1802         READ_LOCK(cmd);
1803         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1804         READ_UNLOCK(cmd);
1805
1806         return 0;
1807 }
1808
1809 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1810 {
1811         int r;
1812
1813         WRITE_LOCK(cmd);
1814         __destroy_persistent_data_objects(cmd);
1815         r = __create_persistent_data_objects(cmd, false);
1816         if (r)
1817                 cmd->fail_io = true;
1818         WRITE_UNLOCK(cmd);
1819
1820         return r;
1821 }