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