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
  17 /*----------------------------------------------------------------*/
  18
  19 #define DM_MSG_PREFIX   "cache metadata"
  20
  21 #define CACHE_SUPERBLOCK_MAGIC 06142003
  22 #define CACHE_SUPERBLOCK_LOCATION 0
  23
  24 /*
  25  * defines a range of metadata versions that this module can handle.
  26  */
  27 #define MIN_CACHE_VERSION 1
  28 #define MAX_CACHE_VERSION 1
  29
  30 #define CACHE_METADATA_CACHE_SIZE 64
  31
  32 /*
  33  *  3 for btree insert +
  34  *  2 for btree lookup used within space map
  35  */
  36 #define CACHE_MAX_CONCURRENT_LOCKS 5
  37 #define SPACE_MAP_ROOT_SIZE 128
  38
  39 enum superblock_flag_bits {
  40         /* for spotting crashes that would invalidate the dirty bitset */
  41         CLEAN_SHUTDOWN,
  42         /* metadata must be checked using the tools */
  43         NEEDS_CHECK,
  44 };
  45
  46 /*
  47  * Each mapping from cache block -> origin block carries a set of flags.
  48  */
  49 enum mapping_bits {
  50         /*
  51          * A valid mapping.  Because we're using an array we clear this
  52          * flag for an non existant mapping.
  53          */
  54         M_VALID = 1,
  55
  56         /*
  57          * The data on the cache is different from that on the origin.
  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 } __packed;
  97
  98 struct dm_cache_metadata {
  99         atomic_t ref_count;
 100         struct list_head list;
 101
 102         struct block_device *bdev;
 103         struct dm_block_manager *bm;
 104         struct dm_space_map *metadata_sm;
 105         struct dm_transaction_manager *tm;
 106
 107         struct dm_array_info info;
 108         struct dm_array_info hint_info;
 109         struct dm_disk_bitset discard_info;
 110
 111         struct rw_semaphore root_lock;
 112         unsigned long flags;
 113         dm_block_t root;
 114         dm_block_t hint_root;
 115         dm_block_t discard_root;
 116
 117         sector_t discard_block_size;
 118         dm_dblock_t discard_nr_blocks;
 119
 120         sector_t data_block_size;
 121         dm_cblock_t cache_blocks;
 122         bool changed:1;
 123         bool clean_when_opened:1;
 124
 125         char policy_name[CACHE_POLICY_NAME_SIZE];
 126         unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
 127         size_t policy_hint_size;
 128         struct dm_cache_statistics stats;
 129
 130         /*
 131          * Reading the space map root can fail, so we read it into this
 132          * buffer before the superblock is locked and updated.
 133          */
 134         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 135
 136         /*
 137          * Set if a transaction has to be aborted but the attempt to roll
 138          * back to the previous (good) transaction failed.  The only
 139          * metadata operation permissible in this state is the closing of
 140          * the device.
 141          */
 142         bool fail_io:1;
 143 };
 144
 145 /*-------------------------------------------------------------------
 146  * superblock validator
 147  *-----------------------------------------------------------------*/
 148
 149 #define SUPERBLOCK_CSUM_XOR 9031977
 150
 151 static void sb_prepare_for_write(struct dm_block_validator *v,
 152                                  struct dm_block *b,
 153                                  size_t sb_block_size)
 154 {
 155         struct cache_disk_superblock *disk_super = dm_block_data(b);
 156
 157         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 158         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 159                                                       sb_block_size - sizeof(__le32),
 160                                                       SUPERBLOCK_CSUM_XOR));
 161 }
 162
 163 static int check_metadata_version(struct cache_disk_superblock *disk_super)
 164 {
 165         uint32_t metadata_version = le32_to_cpu(disk_super->version);
 166         if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
 167                 DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
 168                       metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
 169                 return -EINVAL;
 170         }
 171
 172         return 0;
 173 }
 174
 175 static int sb_check(struct dm_block_validator *v,
 176                     struct dm_block *b,
 177                     size_t sb_block_size)
 178 {
 179         struct cache_disk_superblock *disk_super = dm_block_data(b);
 180         __le32 csum_le;
 181
 182         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 183                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 184                       le64_to_cpu(disk_super->blocknr),
 185                       (unsigned long long)dm_block_location(b));
 186                 return -ENOTBLK;
 187         }
 188
 189         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
 190                 DMERR("sb_check failed: magic %llu: wanted %llu",
 191                       le64_to_cpu(disk_super->magic),
 192                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
 193                 return -EILSEQ;
 194         }
 195
 196         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 197                                              sb_block_size - sizeof(__le32),
 198                                              SUPERBLOCK_CSUM_XOR));
 199         if (csum_le != disk_super->csum) {
 200                 DMERR("sb_check failed: csum %u: wanted %u",
 201                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 202                 return -EILSEQ;
 203         }
 204
 205         return check_metadata_version(disk_super);
 206 }
 207
 208 static struct dm_block_validator sb_validator = {
 209         .name = "superblock",
 210         .prepare_for_write = sb_prepare_for_write,
 211         .check = sb_check
 212 };
 213
 214 /*----------------------------------------------------------------*/
 215
 216 static int superblock_read_lock(struct dm_cache_metadata *cmd,
 217                                 struct dm_block **sblock)
 218 {
 219         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 220                                &sb_validator, sblock);
 221 }
 222
 223 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
 224                                 struct dm_block **sblock)
 225 {
 226         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 227                                      &sb_validator, sblock);
 228 }
 229
 230 static int superblock_lock(struct dm_cache_metadata *cmd,
 231                            struct dm_block **sblock)
 232 {
 233         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 234                                 &sb_validator, sblock);
 235 }
 236
 237 /*----------------------------------------------------------------*/
 238
 239 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 240 {
 241         int r;
 242         unsigned i;
 243         struct dm_block *b;
 244         __le64 *data_le, zero = cpu_to_le64(0);
 245         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 246
 247         /*
 248          * We can't use a validator here - it may be all zeroes.
 249          */
 250         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
 251         if (r)
 252                 return r;
 253
 254         data_le = dm_block_data(b);
 255         *result = true;
 256         for (i = 0; i < sb_block_size; i++) {
 257                 if (data_le[i] != zero) {
 258                         *result = false;
 259                         break;
 260                 }
 261         }
 262
 263         dm_bm_unlock(b);
 264
 265         return 0;
 266 }
 267
 268 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 269 {
 270         struct dm_btree_value_type vt;
 271
 272         vt.context = NULL;
 273         vt.size = sizeof(__le64);
 274         vt.inc = NULL;
 275         vt.dec = NULL;
 276         vt.equal = NULL;
 277         dm_array_info_init(&cmd->info, cmd->tm, &vt);
 278
 279         if (cmd->policy_hint_size) {
 280                 vt.size = sizeof(__le32);
 281                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
 282         }
 283 }
 284
 285 static int __save_sm_root(struct dm_cache_metadata *cmd)
 286 {
 287         int r;
 288         size_t metadata_len;
 289
 290         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 291         if (r < 0)
 292                 return r;
 293
 294         return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
 295                                metadata_len);
 296 }
 297
 298 static void __copy_sm_root(struct dm_cache_metadata *cmd,
 299                            struct cache_disk_superblock *disk_super)
 300 {
 301         memcpy(&disk_super->metadata_space_map_root,
 302                &cmd->metadata_space_map_root,
 303                sizeof(cmd->metadata_space_map_root));
 304 }
 305
 306 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 307 {
 308         int r;
 309         struct dm_block *sblock;
 310         struct cache_disk_superblock *disk_super;
 311         sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
 312
 313         /* FIXME: see if we can lose the max sectors limit */
 314         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 315                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 316
 317         r = dm_tm_pre_commit(cmd->tm);
 318         if (r < 0)
 319                 return r;
 320
 321         /*
 322          * dm_sm_copy_root() can fail.  So we need to do it before we start
 323          * updating the superblock.
 324          */
 325         r = __save_sm_root(cmd);
 326         if (r)
 327                 return r;
 328
 329         r = superblock_lock_zero(cmd, &sblock);
 330         if (r)
 331                 return r;
 332
 333         disk_super = dm_block_data(sblock);
 334         disk_super->flags = 0;
 335         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 336         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
 337         disk_super->version = cpu_to_le32(MAX_CACHE_VERSION);
 338         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 339         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
 340         disk_super->policy_hint_size = 0;
 341
 342         __copy_sm_root(cmd, disk_super);
 343
 344         disk_super->mapping_root = cpu_to_le64(cmd->root);
 345         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 346         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 347         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 348         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 349         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
 350         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 351         disk_super->cache_blocks = cpu_to_le32(0);
 352
 353         disk_super->read_hits = cpu_to_le32(0);
 354         disk_super->read_misses = cpu_to_le32(0);
 355         disk_super->write_hits = cpu_to_le32(0);
 356         disk_super->write_misses = cpu_to_le32(0);
 357
 358         return dm_tm_commit(cmd->tm, sblock);
 359 }
 360
 361 static int __format_metadata(struct dm_cache_metadata *cmd)
 362 {
 363         int r;
 364
 365         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 366                                  &cmd->tm, &cmd->metadata_sm);
 367         if (r < 0) {
 368                 DMERR("tm_create_with_sm failed");
 369                 return r;
 370         }
 371
 372         __setup_mapping_info(cmd);
 373
 374         r = dm_array_empty(&cmd->info, &cmd->root);
 375         if (r < 0)
 376                 goto bad;
 377
 378         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 379
 380         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
 381         if (r < 0)
 382                 goto bad;
 383
 384         cmd->discard_block_size = 0;
 385         cmd->discard_nr_blocks = 0;
 386
 387         r = __write_initial_superblock(cmd);
 388         if (r)
 389                 goto bad;
 390
 391         cmd->clean_when_opened = true;
 392         return 0;
 393
 394 bad:
 395         dm_tm_destroy(cmd->tm);
 396         dm_sm_destroy(cmd->metadata_sm);
 397
 398         return r;
 399 }
 400
 401 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
 402                                      struct dm_cache_metadata *cmd)
 403 {
 404         uint32_t features;
 405
 406         features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
 407         if (features) {
 408                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 409                       (unsigned long)features);
 410                 return -EINVAL;
 411         }
 412
 413         /*
 414          * Check for read-only metadata to skip the following RDWR checks.
 415          */
 416         if (get_disk_ro(cmd->bdev->bd_disk))
 417                 return 0;
 418
 419         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
 420         if (features) {
 421                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 422                       (unsigned long)features);
 423                 return -EINVAL;
 424         }
 425
 426         return 0;
 427 }
 428
 429 static int __open_metadata(struct dm_cache_metadata *cmd)
 430 {
 431         int r;
 432         struct dm_block *sblock;
 433         struct cache_disk_superblock *disk_super;
 434         unsigned long sb_flags;
 435
 436         r = superblock_read_lock(cmd, &sblock);
 437         if (r < 0) {
 438                 DMERR("couldn't read lock superblock");
 439                 return r;
 440         }
 441
 442         disk_super = dm_block_data(sblock);
 443
 444         /* Verify the data block size hasn't changed */
 445         if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
 446                 DMERR("changing the data block size (from %u to %llu) is not supported",
 447                       le32_to_cpu(disk_super->data_block_size),
 448                       (unsigned long long)cmd->data_block_size);
 449                 r = -EINVAL;
 450                 goto bad;
 451         }
 452
 453         r = __check_incompat_features(disk_super, cmd);
 454         if (r < 0)
 455                 goto bad;
 456
 457         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 458                                disk_super->metadata_space_map_root,
 459                                sizeof(disk_super->metadata_space_map_root),
 460                                &cmd->tm, &cmd->metadata_sm);
 461         if (r < 0) {
 462                 DMERR("tm_open_with_sm failed");
 463                 goto bad;
 464         }
 465
 466         __setup_mapping_info(cmd);
 467         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 468         sb_flags = le32_to_cpu(disk_super->flags);
 469         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 470         dm_bm_unlock(sblock);
 471
 472         return 0;
 473
 474 bad:
 475         dm_bm_unlock(sblock);
 476         return r;
 477 }
 478
 479 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 480                                      bool format_device)
 481 {
 482         int r;
 483         bool unformatted = false;
 484
 485         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 486         if (r)
 487                 return r;
 488
 489         if (unformatted)
 490                 return format_device ? __format_metadata(cmd) : -EPERM;
 491
 492         return __open_metadata(cmd);
 493 }
 494
 495 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 496                                             bool may_format_device)
 497 {
 498         int r;
 499         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 500                                           CACHE_METADATA_CACHE_SIZE,
 501                                           CACHE_MAX_CONCURRENT_LOCKS);
 502         if (IS_ERR(cmd->bm)) {
 503                 DMERR("could not create block manager");
 504                 return PTR_ERR(cmd->bm);
 505         }
 506
 507         r = __open_or_format_metadata(cmd, may_format_device);
 508         if (r)
 509                 dm_block_manager_destroy(cmd->bm);
 510
 511         return r;
 512 }
 513
 514 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
 515 {
 516         dm_sm_destroy(cmd->metadata_sm);
 517         dm_tm_destroy(cmd->tm);
 518         dm_block_manager_destroy(cmd->bm);
 519 }
 520
 521 typedef unsigned long (*flags_mutator)(unsigned long);
 522
 523 static void update_flags(struct cache_disk_superblock *disk_super,
 524                          flags_mutator mutator)
 525 {
 526         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 527         disk_super->flags = cpu_to_le32(sb_flags);
 528 }
 529
 530 static unsigned long set_clean_shutdown(unsigned long flags)
 531 {
 532         set_bit(CLEAN_SHUTDOWN, &flags);
 533         return flags;
 534 }
 535
 536 static unsigned long clear_clean_shutdown(unsigned long flags)
 537 {
 538         clear_bit(CLEAN_SHUTDOWN, &flags);
 539         return flags;
 540 }
 541
 542 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 543                                    struct cache_disk_superblock *disk_super)
 544 {
 545         cmd->flags = le32_to_cpu(disk_super->flags);
 546         cmd->root = le64_to_cpu(disk_super->mapping_root);
 547         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 548         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 549         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 550         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
 551         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 552         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 553         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 554         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 555         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 556         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 557         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 558
 559         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 560         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 561         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 562         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 563
 564         cmd->changed = false;
 565 }
 566
 567 /*
 568  * The mutator updates the superblock flags.
 569  */
 570 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 571                                      flags_mutator mutator)
 572 {
 573         int r;
 574         struct cache_disk_superblock *disk_super;
 575         struct dm_block *sblock;
 576
 577         r = superblock_lock(cmd, &sblock);
 578         if (r)
 579                 return r;
 580
 581         disk_super = dm_block_data(sblock);
 582         update_flags(disk_super, mutator);
 583         read_superblock_fields(cmd, disk_super);
 584         dm_bm_unlock(sblock);
 585
 586         return dm_bm_flush(cmd->bm);
 587 }
 588
 589 static int __begin_transaction(struct dm_cache_metadata *cmd)
 590 {
 591         int r;
 592         struct cache_disk_superblock *disk_super;
 593         struct dm_block *sblock;
 594
 595         /*
 596          * We re-read the superblock every time.  Shouldn't need to do this
 597          * really.
 598          */
 599         r = superblock_read_lock(cmd, &sblock);
 600         if (r)
 601                 return r;
 602
 603         disk_super = dm_block_data(sblock);
 604         read_superblock_fields(cmd, disk_super);
 605         dm_bm_unlock(sblock);
 606
 607         return 0;
 608 }
 609
 610 static int __commit_transaction(struct dm_cache_metadata *cmd,
 611                                 flags_mutator mutator)
 612 {
 613         int r;
 614         struct cache_disk_superblock *disk_super;
 615         struct dm_block *sblock;
 616
 617         /*
 618          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 619          */
 620         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 621
 622         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 623                             &cmd->discard_root);
 624         if (r)
 625                 return r;
 626
 627         r = dm_tm_pre_commit(cmd->tm);
 628         if (r < 0)
 629                 return r;
 630
 631         r = __save_sm_root(cmd);
 632         if (r)
 633                 return r;
 634
 635         r = superblock_lock(cmd, &sblock);
 636         if (r)
 637                 return r;
 638
 639         disk_super = dm_block_data(sblock);
 640
 641         disk_super->flags = cpu_to_le32(cmd->flags);
 642         if (mutator)
 643                 update_flags(disk_super, mutator);
 644
 645         disk_super->mapping_root = cpu_to_le64(cmd->root);
 646         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 647         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 648         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 649         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 650         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 651         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 652         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 653         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 654         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 655
 656         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 657         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 658         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 659         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 660         __copy_sm_root(cmd, disk_super);
 661
 662         return dm_tm_commit(cmd->tm, sblock);
 663 }
 664
 665 /*----------------------------------------------------------------*/
 666
 667 /*
 668  * The mappings are held in a dm-array that has 64-bit values stored in
 669  * little-endian format.  The index is the cblock, the high 48bits of the
 670  * value are the oblock and the low 16 bit the flags.
 671  */
 672 #define FLAGS_MASK ((1 << 16) - 1)
 673
 674 static __le64 pack_value(dm_oblock_t block, unsigned flags)
 675 {
 676         uint64_t value = from_oblock(block);
 677         value <<= 16;
 678         value = value | (flags & FLAGS_MASK);
 679         return cpu_to_le64(value);
 680 }
 681
 682 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 683 {
 684         uint64_t value = le64_to_cpu(value_le);
 685         uint64_t b = value >> 16;
 686         *block = to_oblock(b);
 687         *flags = value & FLAGS_MASK;
 688 }
 689
 690 /*----------------------------------------------------------------*/
 691
 692 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
 693                                                sector_t data_block_size,
 694                                                bool may_format_device,
 695                                                size_t policy_hint_size)
 696 {
 697         int r;
 698         struct dm_cache_metadata *cmd;
 699
 700         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 701         if (!cmd) {
 702                 DMERR("could not allocate metadata struct");
 703                 return ERR_PTR(-ENOMEM);
 704         }
 705
 706         atomic_set(&cmd->ref_count, 1);
 707         init_rwsem(&cmd->root_lock);
 708         cmd->bdev = bdev;
 709         cmd->data_block_size = data_block_size;
 710         cmd->cache_blocks = 0;
 711         cmd->policy_hint_size = policy_hint_size;
 712         cmd->changed = true;
 713         cmd->fail_io = false;
 714
 715         r = __create_persistent_data_objects(cmd, may_format_device);
 716         if (r) {
 717                 kfree(cmd);
 718                 return ERR_PTR(r);
 719         }
 720
 721         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 722         if (r < 0) {
 723                 dm_cache_metadata_close(cmd);
 724                 return ERR_PTR(r);
 725         }
 726
 727         return cmd;
 728 }
 729
 730 /*
 731  * We keep a little list of ref counted metadata objects to prevent two
 732  * different target instances creating separate bufio instances.  This is
 733  * an issue if a table is reloaded before the suspend.
 734  */
 735 static DEFINE_MUTEX(table_lock);
 736 static LIST_HEAD(table);
 737
 738 static struct dm_cache_metadata *lookup(struct block_device *bdev)
 739 {
 740         struct dm_cache_metadata *cmd;
 741
 742         list_for_each_entry(cmd, &table, list)
 743                 if (cmd->bdev == bdev) {
 744                         atomic_inc(&cmd->ref_count);
 745                         return cmd;
 746                 }
 747
 748         return NULL;
 749 }
 750
 751 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
 752                                                 sector_t data_block_size,
 753                                                 bool may_format_device,
 754                                                 size_t policy_hint_size)
 755 {
 756         struct dm_cache_metadata *cmd, *cmd2;
 757
 758         mutex_lock(&table_lock);
 759         cmd = lookup(bdev);
 760         mutex_unlock(&table_lock);
 761
 762         if (cmd)
 763                 return cmd;
 764
 765         cmd = metadata_open(bdev, data_block_size, may_format_device, policy_hint_size);
 766         if (!IS_ERR(cmd)) {
 767                 mutex_lock(&table_lock);
 768                 cmd2 = lookup(bdev);
 769                 if (cmd2) {
 770                         mutex_unlock(&table_lock);
 771                         __destroy_persistent_data_objects(cmd);
 772                         kfree(cmd);
 773                         return cmd2;
 774                 }
 775                 list_add(&cmd->list, &table);
 776                 mutex_unlock(&table_lock);
 777         }
 778
 779         return cmd;
 780 }
 781
 782 static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
 783 {
 784         if (cmd->data_block_size != data_block_size) {
 785                 DMERR("data_block_size (%llu) different from that in metadata (%llu)\n",
 786                       (unsigned long long) data_block_size,
 787                       (unsigned long long) cmd->data_block_size);
 788                 return false;
 789         }
 790
 791         return true;
 792 }
 793
 794 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 795                                                  sector_t data_block_size,
 796                                                  bool may_format_device,
 797                                                  size_t policy_hint_size)
 798 {
 799         struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size,
 800                                                        may_format_device, policy_hint_size);
 801
 802         if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
 803                 dm_cache_metadata_close(cmd);
 804                 return ERR_PTR(-EINVAL);
 805         }
 806
 807         return cmd;
 808 }
 809
 810 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 811 {
 812         if (atomic_dec_and_test(&cmd->ref_count)) {
 813                 mutex_lock(&table_lock);
 814                 list_del(&cmd->list);
 815                 mutex_unlock(&table_lock);
 816
 817                 if (!cmd->fail_io)
 818                         __destroy_persistent_data_objects(cmd);
 819                 kfree(cmd);
 820         }
 821 }
 822
 823 /*
 824  * Checks that the given cache block is either unmapped or clean.
 825  */
 826 static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
 827                                    bool *result)
 828 {
 829         int r;
 830         __le64 value;
 831         dm_oblock_t ob;
 832         unsigned flags;
 833
 834         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
 835         if (r) {
 836                 DMERR("block_unmapped_or_clean failed");
 837                 return r;
 838         }
 839
 840         unpack_value(value, &ob, &flags);
 841         *result = !((flags & M_VALID) && (flags & M_DIRTY));
 842
 843         return 0;
 844 }
 845
 846 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 847                                         dm_cblock_t begin, dm_cblock_t end,
 848                                         bool *result)
 849 {
 850         int r;
 851         *result = true;
 852
 853         while (begin != end) {
 854                 r = block_unmapped_or_clean(cmd, begin, result);
 855                 if (r)
 856                         return r;
 857
 858                 if (!*result) {
 859                         DMERR("cache block %llu is dirty",
 860                               (unsigned long long) from_cblock(begin));
 861                         return 0;
 862                 }
 863
 864                 begin = to_cblock(from_cblock(begin) + 1);
 865         }
 866
 867         return 0;
 868 }
 869
 870 #define WRITE_LOCK(cmd) \
 871         down_write(&cmd->root_lock); \
 872         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \
 873                 up_write(&cmd->root_lock); \
 874                 return -EINVAL; \
 875         }
 876
 877 #define WRITE_LOCK_VOID(cmd) \
 878         down_write(&cmd->root_lock); \
 879         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \
 880                 up_write(&cmd->root_lock); \
 881                 return; \
 882         }
 883
 884 #define WRITE_UNLOCK(cmd) \
 885         up_write(&cmd->root_lock)
 886
 887 #define READ_LOCK(cmd) \
 888         down_read(&cmd->root_lock); \
 889         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \
 890                 up_read(&cmd->root_lock); \
 891                 return -EINVAL; \
 892         }
 893
 894 #define READ_LOCK_VOID(cmd)     \
 895         down_read(&cmd->root_lock); \
 896         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \
 897                 up_read(&cmd->root_lock); \
 898                 return; \
 899         }
 900
 901 #define READ_UNLOCK(cmd) \
 902         up_read(&cmd->root_lock)
 903
 904 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 905 {
 906         int r;
 907         bool clean;
 908         __le64 null_mapping = pack_value(0, 0);
 909
 910         WRITE_LOCK(cmd);
 911         __dm_bless_for_disk(&null_mapping);
 912
 913         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
 914                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
 915                 if (r) {
 916                         __dm_unbless_for_disk(&null_mapping);
 917                         goto out;
 918                 }
 919
 920                 if (!clean) {
 921                         DMERR("unable to shrink cache due to dirty blocks");
 922                         r = -EINVAL;
 923                         __dm_unbless_for_disk(&null_mapping);
 924                         goto out;
 925                 }
 926         }
 927
 928         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
 929                             from_cblock(new_cache_size),
 930                             &null_mapping, &cmd->root);
 931         if (!r)
 932                 cmd->cache_blocks = new_cache_size;
 933         cmd->changed = true;
 934
 935 out:
 936         WRITE_UNLOCK(cmd);
 937
 938         return r;
 939 }
 940
 941 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 942                                    sector_t discard_block_size,
 943                                    dm_dblock_t new_nr_entries)
 944 {
 945         int r;
 946
 947         WRITE_LOCK(cmd);
 948         r = dm_bitset_resize(&cmd->discard_info,
 949                              cmd->discard_root,
 950                              from_dblock(cmd->discard_nr_blocks),
 951                              from_dblock(new_nr_entries),
 952                              false, &cmd->discard_root);
 953         if (!r) {
 954                 cmd->discard_block_size = discard_block_size;
 955                 cmd->discard_nr_blocks = new_nr_entries;
 956         }
 957
 958         cmd->changed = true;
 959         WRITE_UNLOCK(cmd);
 960
 961         return r;
 962 }
 963
 964 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
 965 {
 966         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
 967                                  from_dblock(b), &cmd->discard_root);
 968 }
 969
 970 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
 971 {
 972         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
 973                                    from_dblock(b), &cmd->discard_root);
 974 }
 975
 976 static int __is_discarded(struct dm_cache_metadata *cmd, dm_dblock_t b,
 977                           bool *is_discarded)
 978 {
 979         return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
 980                                   from_dblock(b), &cmd->discard_root,
 981                                   is_discarded);
 982 }
 983
 984 static int __discard(struct dm_cache_metadata *cmd,
 985                      dm_dblock_t dblock, bool discard)
 986 {
 987         int r;
 988
 989         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
 990         if (r)
 991                 return r;
 992
 993         cmd->changed = true;
 994         return 0;
 995 }
 996
 997 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
 998                          dm_dblock_t dblock, bool discard)
 999 {
1000         int r;
1001
1002         WRITE_LOCK(cmd);
1003         r = __discard(cmd, dblock, discard);
1004         WRITE_UNLOCK(cmd);
1005
1006         return r;
1007 }
1008
1009 static int __load_discards(struct dm_cache_metadata *cmd,
1010                            load_discard_fn fn, void *context)
1011 {
1012         int r = 0;
1013         dm_block_t b;
1014         bool discard;
1015
1016         for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1017                 dm_dblock_t dblock = to_dblock(b);
1018
1019                 if (cmd->clean_when_opened) {
1020                         r = __is_discarded(cmd, dblock, &discard);
1021                         if (r)
1022                                 return r;
1023                 } else
1024                         discard = false;
1025
1026                 r = fn(context, cmd->discard_block_size, dblock, discard);
1027                 if (r)
1028                         break;
1029         }
1030
1031         return r;
1032 }
1033
1034 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1035                            load_discard_fn fn, void *context)
1036 {
1037         int r;
1038
1039         READ_LOCK(cmd);
1040         r = __load_discards(cmd, fn, context);
1041         READ_UNLOCK(cmd);
1042
1043         return r;
1044 }
1045
1046 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1047 {
1048         READ_LOCK(cmd);
1049         *result = cmd->cache_blocks;
1050         READ_UNLOCK(cmd);
1051
1052         return 0;
1053 }
1054
1055 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1056 {
1057         int r;
1058         __le64 value = pack_value(0, 0);
1059
1060         __dm_bless_for_disk(&value);
1061         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1062                                &value, &cmd->root);
1063         if (r)
1064                 return r;
1065
1066         cmd->changed = true;
1067         return 0;
1068 }
1069
1070 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1071 {
1072         int r;
1073
1074         WRITE_LOCK(cmd);
1075         r = __remove(cmd, cblock);
1076         WRITE_UNLOCK(cmd);
1077
1078         return r;
1079 }
1080
1081 static int __insert(struct dm_cache_metadata *cmd,
1082                     dm_cblock_t cblock, dm_oblock_t oblock)
1083 {
1084         int r;
1085         __le64 value = pack_value(oblock, M_VALID);
1086         __dm_bless_for_disk(&value);
1087
1088         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1089                                &value, &cmd->root);
1090         if (r)
1091                 return r;
1092
1093         cmd->changed = true;
1094         return 0;
1095 }
1096
1097 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1098                             dm_cblock_t cblock, dm_oblock_t oblock)
1099 {
1100         int r;
1101
1102         WRITE_LOCK(cmd);
1103         r = __insert(cmd, cblock, oblock);
1104         WRITE_UNLOCK(cmd);
1105
1106         return r;
1107 }
1108
1109 struct thunk {
1110         load_mapping_fn fn;
1111         void *context;
1112
1113         struct dm_cache_metadata *cmd;
1114         bool respect_dirty_flags;
1115         bool hints_valid;
1116 };
1117
1118 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1119                              struct dm_cache_policy *policy)
1120 {
1121         const char *policy_name = dm_cache_policy_get_name(policy);
1122         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1123         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1124
1125         /*
1126          * Ensure policy names match.
1127          */
1128         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1129                 return false;
1130
1131         /*
1132          * Ensure policy major versions match.
1133          */
1134         if (cmd->policy_version[0] != policy_version[0])
1135                 return false;
1136
1137         /*
1138          * Ensure policy hint sizes match.
1139          */
1140         if (cmd->policy_hint_size != policy_hint_size)
1141                 return false;
1142
1143         return true;
1144 }
1145
1146 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1147 {
1148         return cmd->hint_root && cmd->policy_hint_size;
1149 }
1150
1151 static bool hints_array_available(struct dm_cache_metadata *cmd,
1152                                   struct dm_cache_policy *policy)
1153 {
1154         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1155                 hints_array_initialized(cmd);
1156 }
1157
1158 static int __load_mapping(void *context, uint64_t cblock, void *leaf)
1159 {
1160         int r = 0;
1161         bool dirty;
1162         __le64 value;
1163         __le32 hint_value = 0;
1164         dm_oblock_t oblock;
1165         unsigned flags;
1166         struct thunk *thunk = context;
1167         struct dm_cache_metadata *cmd = thunk->cmd;
1168
1169         memcpy(&value, leaf, sizeof(value));
1170         unpack_value(value, &oblock, &flags);
1171
1172         if (flags & M_VALID) {
1173                 if (thunk->hints_valid) {
1174                         r = dm_array_get_value(&cmd->hint_info, cmd->hint_root,
1175                                                cblock, &hint_value);
1176                         if (r && r != -ENODATA)
1177                                 return r;
1178                 }
1179
1180                 dirty = thunk->respect_dirty_flags ? (flags & M_DIRTY) : true;
1181                 r = thunk->fn(thunk->context, oblock, to_cblock(cblock),
1182                               dirty, le32_to_cpu(hint_value), thunk->hints_valid);
1183         }
1184
1185         return r;
1186 }
1187
1188 static int __load_mappings(struct dm_cache_metadata *cmd,
1189                            struct dm_cache_policy *policy,
1190                            load_mapping_fn fn, void *context)
1191 {
1192         struct thunk thunk;
1193
1194         thunk.fn = fn;
1195         thunk.context = context;
1196
1197         thunk.cmd = cmd;
1198         thunk.respect_dirty_flags = cmd->clean_when_opened;
1199         thunk.hints_valid = hints_array_available(cmd, policy);
1200
1201         return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
1202 }
1203
1204 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1205                            struct dm_cache_policy *policy,
1206                            load_mapping_fn fn, void *context)
1207 {
1208         int r;
1209
1210         READ_LOCK(cmd);
1211         r = __load_mappings(cmd, policy, fn, context);
1212         READ_UNLOCK(cmd);
1213
1214         return r;
1215 }
1216
1217 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1218 {
1219         int r = 0;
1220         __le64 value;
1221         dm_oblock_t oblock;
1222         unsigned flags;
1223
1224         memcpy(&value, leaf, sizeof(value));
1225         unpack_value(value, &oblock, &flags);
1226
1227         return r;
1228 }
1229
1230 static int __dump_mappings(struct dm_cache_metadata *cmd)
1231 {
1232         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1233 }
1234
1235 void dm_cache_dump(struct dm_cache_metadata *cmd)
1236 {
1237         READ_LOCK_VOID(cmd);
1238         __dump_mappings(cmd);
1239         READ_UNLOCK(cmd);
1240 }
1241
1242 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1243 {
1244         int r;
1245
1246         READ_LOCK(cmd);
1247         r = cmd->changed;
1248         READ_UNLOCK(cmd);
1249
1250         return r;
1251 }
1252
1253 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1254 {
1255         int r;
1256         unsigned flags;
1257         dm_oblock_t oblock;
1258         __le64 value;
1259
1260         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1261         if (r)
1262                 return r;
1263
1264         unpack_value(value, &oblock, &flags);
1265
1266         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1267                 /* nothing to be done */
1268                 return 0;
1269
1270         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1271         __dm_bless_for_disk(&value);
1272
1273         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1274                                &value, &cmd->root);
1275         if (r)
1276                 return r;
1277
1278         cmd->changed = true;
1279         return 0;
1280
1281 }
1282
1283 int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
1284                        dm_cblock_t cblock, bool dirty)
1285 {
1286         int r;
1287
1288         WRITE_LOCK(cmd);
1289         r = __dirty(cmd, cblock, dirty);
1290         WRITE_UNLOCK(cmd);
1291
1292         return r;
1293 }
1294
1295 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1296                                  struct dm_cache_statistics *stats)
1297 {
1298         READ_LOCK_VOID(cmd);
1299         *stats = cmd->stats;
1300         READ_UNLOCK(cmd);
1301 }
1302
1303 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1304                                  struct dm_cache_statistics *stats)
1305 {
1306         WRITE_LOCK_VOID(cmd);
1307         cmd->stats = *stats;
1308         WRITE_UNLOCK(cmd);
1309 }
1310
1311 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1312 {
1313         int r;
1314         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1315                                  clear_clean_shutdown);
1316
1317         WRITE_LOCK(cmd);
1318         r = __commit_transaction(cmd, mutator);
1319         if (r)
1320                 goto out;
1321
1322         r = __begin_transaction(cmd);
1323
1324 out:
1325         WRITE_UNLOCK(cmd);
1326         return r;
1327 }
1328
1329 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1330                                            dm_block_t *result)
1331 {
1332         int r = -EINVAL;
1333
1334         READ_LOCK(cmd);
1335         r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1336         READ_UNLOCK(cmd);
1337
1338         return r;
1339 }
1340
1341 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1342                                    dm_block_t *result)
1343 {
1344         int r = -EINVAL;
1345
1346         READ_LOCK(cmd);
1347         r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1348         READ_UNLOCK(cmd);
1349
1350         return r;
1351 }
1352
1353 /*----------------------------------------------------------------*/
1354
1355 static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1356 {
1357         int r;
1358         __le32 value;
1359         size_t hint_size;
1360         const char *policy_name = dm_cache_policy_get_name(policy);
1361         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1362
1363         if (!policy_name[0] ||
1364             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1365                 return -EINVAL;
1366
1367         if (!policy_unchanged(cmd, policy)) {
1368                 strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1369                 memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1370
1371                 hint_size = dm_cache_policy_get_hint_size(policy);
1372                 if (!hint_size)
1373                         return 0; /* short-circuit hints initialization */
1374                 cmd->policy_hint_size = hint_size;
1375
1376                 if (cmd->hint_root) {
1377                         r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1378                         if (r)
1379                                 return r;
1380                 }
1381
1382                 r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
1383                 if (r)
1384                         return r;
1385
1386                 value = cpu_to_le32(0);
1387                 __dm_bless_for_disk(&value);
1388                 r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
1389                                     from_cblock(cmd->cache_blocks),
1390                                     &value, &cmd->hint_root);
1391                 if (r)
1392                         return r;
1393         }
1394
1395         return 0;
1396 }
1397
1398 static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)
1399 {
1400         struct dm_cache_metadata *cmd = context;
1401         __le32 value = cpu_to_le32(hint);
1402         int r;
1403
1404         __dm_bless_for_disk(&value);
1405
1406         r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
1407                                from_cblock(cblock), &value, &cmd->hint_root);
1408         cmd->changed = true;
1409
1410         return r;
1411 }
1412
1413 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1414 {
1415         int r;
1416
1417         r = begin_hints(cmd, policy);
1418         if (r) {
1419                 DMERR("begin_hints failed");
1420                 return r;
1421         }
1422
1423         return policy_walk_mappings(policy, save_hint, cmd);
1424 }
1425
1426 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1427 {
1428         int r;
1429
1430         WRITE_LOCK(cmd);
1431         r = write_hints(cmd, policy);
1432         WRITE_UNLOCK(cmd);
1433
1434         return r;
1435 }
1436
1437 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1438 {
1439         int r;
1440
1441         READ_LOCK(cmd);
1442         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1443         READ_UNLOCK(cmd);
1444
1445         return r;
1446 }
1447
1448 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1449 {
1450         WRITE_LOCK_VOID(cmd);
1451         dm_bm_set_read_only(cmd->bm);
1452         WRITE_UNLOCK(cmd);
1453 }
1454
1455 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1456 {
1457         WRITE_LOCK_VOID(cmd);
1458         dm_bm_set_read_write(cmd->bm);
1459         WRITE_UNLOCK(cmd);
1460 }
1461
1462 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1463 {
1464         int r;
1465         struct dm_block *sblock;
1466         struct cache_disk_superblock *disk_super;
1467
1468         WRITE_LOCK(cmd);
1469         set_bit(NEEDS_CHECK, &cmd->flags);
1470
1471         r = superblock_lock(cmd, &sblock);
1472         if (r) {
1473                 DMERR("couldn't read superblock");
1474                 goto out;
1475         }
1476
1477         disk_super = dm_block_data(sblock);
1478         disk_super->flags = cpu_to_le32(cmd->flags);
1479
1480         dm_bm_unlock(sblock);
1481
1482 out:
1483         WRITE_UNLOCK(cmd);
1484         return r;
1485 }
1486
1487 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1488 {
1489         READ_LOCK(cmd);
1490         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1491         READ_UNLOCK(cmd);
1492
1493         return 0;
1494 }
1495
1496 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1497 {
1498         int r;
1499
1500         WRITE_LOCK(cmd);
1501         __destroy_persistent_data_objects(cmd);
1502         r = __create_persistent_data_objects(cmd, false);
1503         if (r)
1504                 cmd->fail_io = true;
1505         WRITE_UNLOCK(cmd);
1506
1507         return r;
1508 }