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          * These structures are used when loading metadata.  They're too
 146          * big to put on the stack.
 147          */
 148         struct dm_array_cursor mapping_cursor;
 149         struct dm_array_cursor hint_cursor;
 150 };
 151
 152 /*-------------------------------------------------------------------
 153  * superblock validator
 154  *-----------------------------------------------------------------*/
 155
 156 #define SUPERBLOCK_CSUM_XOR 9031977
 157
 158 static void sb_prepare_for_write(struct dm_block_validator *v,
 159                                  struct dm_block *b,
 160                                  size_t sb_block_size)
 161 {
 162         struct cache_disk_superblock *disk_super = dm_block_data(b);
 163
 164         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 165         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 166                                                       sb_block_size - sizeof(__le32),
 167                                                       SUPERBLOCK_CSUM_XOR));
 168 }
 169
 170 static int check_metadata_version(struct cache_disk_superblock *disk_super)
 171 {
 172         uint32_t metadata_version = le32_to_cpu(disk_super->version);
 173         if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
 174                 DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
 175                       metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
 176                 return -EINVAL;
 177         }
 178
 179         return 0;
 180 }
 181
 182 static int sb_check(struct dm_block_validator *v,
 183                     struct dm_block *b,
 184                     size_t sb_block_size)
 185 {
 186         struct cache_disk_superblock *disk_super = dm_block_data(b);
 187         __le32 csum_le;
 188
 189         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 190                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 191                       le64_to_cpu(disk_super->blocknr),
 192                       (unsigned long long)dm_block_location(b));
 193                 return -ENOTBLK;
 194         }
 195
 196         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
 197                 DMERR("sb_check failed: magic %llu: wanted %llu",
 198                       le64_to_cpu(disk_super->magic),
 199                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
 200                 return -EILSEQ;
 201         }
 202
 203         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 204                                              sb_block_size - sizeof(__le32),
 205                                              SUPERBLOCK_CSUM_XOR));
 206         if (csum_le != disk_super->csum) {
 207                 DMERR("sb_check failed: csum %u: wanted %u",
 208                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 209                 return -EILSEQ;
 210         }
 211
 212         return check_metadata_version(disk_super);
 213 }
 214
 215 static struct dm_block_validator sb_validator = {
 216         .name = "superblock",
 217         .prepare_for_write = sb_prepare_for_write,
 218         .check = sb_check
 219 };
 220
 221 /*----------------------------------------------------------------*/
 222
 223 static int superblock_read_lock(struct dm_cache_metadata *cmd,
 224                                 struct dm_block **sblock)
 225 {
 226         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 227                                &sb_validator, sblock);
 228 }
 229
 230 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
 231                                 struct dm_block **sblock)
 232 {
 233         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 234                                      &sb_validator, sblock);
 235 }
 236
 237 static int superblock_lock(struct dm_cache_metadata *cmd,
 238                            struct dm_block **sblock)
 239 {
 240         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 241                                 &sb_validator, sblock);
 242 }
 243
 244 /*----------------------------------------------------------------*/
 245
 246 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 247 {
 248         int r;
 249         unsigned i;
 250         struct dm_block *b;
 251         __le64 *data_le, zero = cpu_to_le64(0);
 252         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 253
 254         /*
 255          * We can't use a validator here - it may be all zeroes.
 256          */
 257         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
 258         if (r)
 259                 return r;
 260
 261         data_le = dm_block_data(b);
 262         *result = true;
 263         for (i = 0; i < sb_block_size; i++) {
 264                 if (data_le[i] != zero) {
 265                         *result = false;
 266                         break;
 267                 }
 268         }
 269
 270         dm_bm_unlock(b);
 271
 272         return 0;
 273 }
 274
 275 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 276 {
 277         struct dm_btree_value_type vt;
 278
 279         vt.context = NULL;
 280         vt.size = sizeof(__le64);
 281         vt.inc = NULL;
 282         vt.dec = NULL;
 283         vt.equal = NULL;
 284         dm_array_info_init(&cmd->info, cmd->tm, &vt);
 285
 286         if (cmd->policy_hint_size) {
 287                 vt.size = sizeof(__le32);
 288                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
 289         }
 290 }
 291
 292 static int __save_sm_root(struct dm_cache_metadata *cmd)
 293 {
 294         int r;
 295         size_t metadata_len;
 296
 297         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 298         if (r < 0)
 299                 return r;
 300
 301         return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
 302                                metadata_len);
 303 }
 304
 305 static void __copy_sm_root(struct dm_cache_metadata *cmd,
 306                            struct cache_disk_superblock *disk_super)
 307 {
 308         memcpy(&disk_super->metadata_space_map_root,
 309                &cmd->metadata_space_map_root,
 310                sizeof(cmd->metadata_space_map_root));
 311 }
 312
 313 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 314 {
 315         int r;
 316         struct dm_block *sblock;
 317         struct cache_disk_superblock *disk_super;
 318         sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
 319
 320         /* FIXME: see if we can lose the max sectors limit */
 321         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 322                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 323
 324         r = dm_tm_pre_commit(cmd->tm);
 325         if (r < 0)
 326                 return r;
 327
 328         /*
 329          * dm_sm_copy_root() can fail.  So we need to do it before we start
 330          * updating the superblock.
 331          */
 332         r = __save_sm_root(cmd);
 333         if (r)
 334                 return r;
 335
 336         r = superblock_lock_zero(cmd, &sblock);
 337         if (r)
 338                 return r;
 339
 340         disk_super = dm_block_data(sblock);
 341         disk_super->flags = 0;
 342         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 343         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
 344         disk_super->version = cpu_to_le32(MAX_CACHE_VERSION);
 345         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 346         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
 347         disk_super->policy_hint_size = 0;
 348
 349         __copy_sm_root(cmd, disk_super);
 350
 351         disk_super->mapping_root = cpu_to_le64(cmd->root);
 352         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 353         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 354         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 355         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 356         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
 357         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 358         disk_super->cache_blocks = cpu_to_le32(0);
 359
 360         disk_super->read_hits = cpu_to_le32(0);
 361         disk_super->read_misses = cpu_to_le32(0);
 362         disk_super->write_hits = cpu_to_le32(0);
 363         disk_super->write_misses = cpu_to_le32(0);
 364
 365         return dm_tm_commit(cmd->tm, sblock);
 366 }
 367
 368 static int __format_metadata(struct dm_cache_metadata *cmd)
 369 {
 370         int r;
 371
 372         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 373                                  &cmd->tm, &cmd->metadata_sm);
 374         if (r < 0) {
 375                 DMERR("tm_create_with_sm failed");
 376                 return r;
 377         }
 378
 379         __setup_mapping_info(cmd);
 380
 381         r = dm_array_empty(&cmd->info, &cmd->root);
 382         if (r < 0)
 383                 goto bad;
 384
 385         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 386
 387         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
 388         if (r < 0)
 389                 goto bad;
 390
 391         cmd->discard_block_size = 0;
 392         cmd->discard_nr_blocks = 0;
 393
 394         r = __write_initial_superblock(cmd);
 395         if (r)
 396                 goto bad;
 397
 398         cmd->clean_when_opened = true;
 399         return 0;
 400
 401 bad:
 402         dm_tm_destroy(cmd->tm);
 403         dm_sm_destroy(cmd->metadata_sm);
 404
 405         return r;
 406 }
 407
 408 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
 409                                      struct dm_cache_metadata *cmd)
 410 {
 411         uint32_t features;
 412
 413         features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
 414         if (features) {
 415                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 416                       (unsigned long)features);
 417                 return -EINVAL;
 418         }
 419
 420         /*
 421          * Check for read-only metadata to skip the following RDWR checks.
 422          */
 423         if (get_disk_ro(cmd->bdev->bd_disk))
 424                 return 0;
 425
 426         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
 427         if (features) {
 428                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 429                       (unsigned long)features);
 430                 return -EINVAL;
 431         }
 432
 433         return 0;
 434 }
 435
 436 static int __open_metadata(struct dm_cache_metadata *cmd)
 437 {
 438         int r;
 439         struct dm_block *sblock;
 440         struct cache_disk_superblock *disk_super;
 441         unsigned long sb_flags;
 442
 443         r = superblock_read_lock(cmd, &sblock);
 444         if (r < 0) {
 445                 DMERR("couldn't read lock superblock");
 446                 return r;
 447         }
 448
 449         disk_super = dm_block_data(sblock);
 450
 451         /* Verify the data block size hasn't changed */
 452         if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
 453                 DMERR("changing the data block size (from %u to %llu) is not supported",
 454                       le32_to_cpu(disk_super->data_block_size),
 455                       (unsigned long long)cmd->data_block_size);
 456                 r = -EINVAL;
 457                 goto bad;
 458         }
 459
 460         r = __check_incompat_features(disk_super, cmd);
 461         if (r < 0)
 462                 goto bad;
 463
 464         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 465                                disk_super->metadata_space_map_root,
 466                                sizeof(disk_super->metadata_space_map_root),
 467                                &cmd->tm, &cmd->metadata_sm);
 468         if (r < 0) {
 469                 DMERR("tm_open_with_sm failed");
 470                 goto bad;
 471         }
 472
 473         __setup_mapping_info(cmd);
 474         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 475         sb_flags = le32_to_cpu(disk_super->flags);
 476         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 477         dm_bm_unlock(sblock);
 478
 479         return 0;
 480
 481 bad:
 482         dm_bm_unlock(sblock);
 483         return r;
 484 }
 485
 486 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 487                                      bool format_device)
 488 {
 489         int r;
 490         bool unformatted = false;
 491
 492         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 493         if (r)
 494                 return r;
 495
 496         if (unformatted)
 497                 return format_device ? __format_metadata(cmd) : -EPERM;
 498
 499         return __open_metadata(cmd);
 500 }
 501
 502 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 503                                             bool may_format_device)
 504 {
 505         int r;
 506         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 507                                           CACHE_METADATA_CACHE_SIZE,
 508                                           CACHE_MAX_CONCURRENT_LOCKS);
 509         if (IS_ERR(cmd->bm)) {
 510                 DMERR("could not create block manager");
 511                 return PTR_ERR(cmd->bm);
 512         }
 513
 514         r = __open_or_format_metadata(cmd, may_format_device);
 515         if (r)
 516                 dm_block_manager_destroy(cmd->bm);
 517
 518         return r;
 519 }
 520
 521 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
 522 {
 523         dm_sm_destroy(cmd->metadata_sm);
 524         dm_tm_destroy(cmd->tm);
 525         dm_block_manager_destroy(cmd->bm);
 526 }
 527
 528 typedef unsigned long (*flags_mutator)(unsigned long);
 529
 530 static void update_flags(struct cache_disk_superblock *disk_super,
 531                          flags_mutator mutator)
 532 {
 533         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 534         disk_super->flags = cpu_to_le32(sb_flags);
 535 }
 536
 537 static unsigned long set_clean_shutdown(unsigned long flags)
 538 {
 539         set_bit(CLEAN_SHUTDOWN, &flags);
 540         return flags;
 541 }
 542
 543 static unsigned long clear_clean_shutdown(unsigned long flags)
 544 {
 545         clear_bit(CLEAN_SHUTDOWN, &flags);
 546         return flags;
 547 }
 548
 549 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 550                                    struct cache_disk_superblock *disk_super)
 551 {
 552         cmd->flags = le32_to_cpu(disk_super->flags);
 553         cmd->root = le64_to_cpu(disk_super->mapping_root);
 554         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 555         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 556         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 557         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
 558         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 559         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 560         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 561         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 562         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 563         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 564         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 565
 566         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 567         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 568         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 569         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 570
 571         cmd->changed = false;
 572 }
 573
 574 /*
 575  * The mutator updates the superblock flags.
 576  */
 577 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 578                                      flags_mutator mutator)
 579 {
 580         int r;
 581         struct cache_disk_superblock *disk_super;
 582         struct dm_block *sblock;
 583
 584         r = superblock_lock(cmd, &sblock);
 585         if (r)
 586                 return r;
 587
 588         disk_super = dm_block_data(sblock);
 589         update_flags(disk_super, mutator);
 590         read_superblock_fields(cmd, disk_super);
 591         dm_bm_unlock(sblock);
 592
 593         return dm_bm_flush(cmd->bm);
 594 }
 595
 596 static int __begin_transaction(struct dm_cache_metadata *cmd)
 597 {
 598         int r;
 599         struct cache_disk_superblock *disk_super;
 600         struct dm_block *sblock;
 601
 602         /*
 603          * We re-read the superblock every time.  Shouldn't need to do this
 604          * really.
 605          */
 606         r = superblock_read_lock(cmd, &sblock);
 607         if (r)
 608                 return r;
 609
 610         disk_super = dm_block_data(sblock);
 611         read_superblock_fields(cmd, disk_super);
 612         dm_bm_unlock(sblock);
 613
 614         return 0;
 615 }
 616
 617 static int __commit_transaction(struct dm_cache_metadata *cmd,
 618                                 flags_mutator mutator)
 619 {
 620         int r;
 621         struct cache_disk_superblock *disk_super;
 622         struct dm_block *sblock;
 623
 624         /*
 625          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 626          */
 627         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 628
 629         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 630                             &cmd->discard_root);
 631         if (r)
 632                 return r;
 633
 634         r = dm_tm_pre_commit(cmd->tm);
 635         if (r < 0)
 636                 return r;
 637
 638         r = __save_sm_root(cmd);
 639         if (r)
 640                 return r;
 641
 642         r = superblock_lock(cmd, &sblock);
 643         if (r)
 644                 return r;
 645
 646         disk_super = dm_block_data(sblock);
 647
 648         disk_super->flags = cpu_to_le32(cmd->flags);
 649         if (mutator)
 650                 update_flags(disk_super, mutator);
 651
 652         disk_super->mapping_root = cpu_to_le64(cmd->root);
 653         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 654         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 655         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 656         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 657         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 658         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 659         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 660         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 661         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 662
 663         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 664         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 665         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 666         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 667         __copy_sm_root(cmd, disk_super);
 668
 669         return dm_tm_commit(cmd->tm, sblock);
 670 }
 671
 672 /*----------------------------------------------------------------*/
 673
 674 /*
 675  * The mappings are held in a dm-array that has 64-bit values stored in
 676  * little-endian format.  The index is the cblock, the high 48bits of the
 677  * value are the oblock and the low 16 bit the flags.
 678  */
 679 #define FLAGS_MASK ((1 << 16) - 1)
 680
 681 static __le64 pack_value(dm_oblock_t block, unsigned flags)
 682 {
 683         uint64_t value = from_oblock(block);
 684         value <<= 16;
 685         value = value | (flags & FLAGS_MASK);
 686         return cpu_to_le64(value);
 687 }
 688
 689 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 690 {
 691         uint64_t value = le64_to_cpu(value_le);
 692         uint64_t b = value >> 16;
 693         *block = to_oblock(b);
 694         *flags = value & FLAGS_MASK;
 695 }
 696
 697 /*----------------------------------------------------------------*/
 698
 699 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
 700                                                sector_t data_block_size,
 701                                                bool may_format_device,
 702                                                size_t policy_hint_size)
 703 {
 704         int r;
 705         struct dm_cache_metadata *cmd;
 706
 707         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 708         if (!cmd) {
 709                 DMERR("could not allocate metadata struct");
 710                 return ERR_PTR(-ENOMEM);
 711         }
 712
 713         atomic_set(&cmd->ref_count, 1);
 714         init_rwsem(&cmd->root_lock);
 715         cmd->bdev = bdev;
 716         cmd->data_block_size = data_block_size;
 717         cmd->cache_blocks = 0;
 718         cmd->policy_hint_size = policy_hint_size;
 719         cmd->changed = true;
 720         cmd->fail_io = false;
 721
 722         r = __create_persistent_data_objects(cmd, may_format_device);
 723         if (r) {
 724                 kfree(cmd);
 725                 return ERR_PTR(r);
 726         }
 727
 728         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 729         if (r < 0) {
 730                 dm_cache_metadata_close(cmd);
 731                 return ERR_PTR(r);
 732         }
 733
 734         return cmd;
 735 }
 736
 737 /*
 738  * We keep a little list of ref counted metadata objects to prevent two
 739  * different target instances creating separate bufio instances.  This is
 740  * an issue if a table is reloaded before the suspend.
 741  */
 742 static DEFINE_MUTEX(table_lock);
 743 static LIST_HEAD(table);
 744
 745 static struct dm_cache_metadata *lookup(struct block_device *bdev)
 746 {
 747         struct dm_cache_metadata *cmd;
 748
 749         list_for_each_entry(cmd, &table, list)
 750                 if (cmd->bdev == bdev) {
 751                         atomic_inc(&cmd->ref_count);
 752                         return cmd;
 753                 }
 754
 755         return NULL;
 756 }
 757
 758 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
 759                                                 sector_t data_block_size,
 760                                                 bool may_format_device,
 761                                                 size_t policy_hint_size)
 762 {
 763         struct dm_cache_metadata *cmd, *cmd2;
 764
 765         mutex_lock(&table_lock);
 766         cmd = lookup(bdev);
 767         mutex_unlock(&table_lock);
 768
 769         if (cmd)
 770                 return cmd;
 771
 772         cmd = metadata_open(bdev, data_block_size, may_format_device, policy_hint_size);
 773         if (!IS_ERR(cmd)) {
 774                 mutex_lock(&table_lock);
 775                 cmd2 = lookup(bdev);
 776                 if (cmd2) {
 777                         mutex_unlock(&table_lock);
 778                         __destroy_persistent_data_objects(cmd);
 779                         kfree(cmd);
 780                         return cmd2;
 781                 }
 782                 list_add(&cmd->list, &table);
 783                 mutex_unlock(&table_lock);
 784         }
 785
 786         return cmd;
 787 }
 788
 789 static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
 790 {
 791         if (cmd->data_block_size != data_block_size) {
 792                 DMERR("data_block_size (%llu) different from that in metadata (%llu)\n",
 793                       (unsigned long long) data_block_size,
 794                       (unsigned long long) cmd->data_block_size);
 795                 return false;
 796         }
 797
 798         return true;
 799 }
 800
 801 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 802                                                  sector_t data_block_size,
 803                                                  bool may_format_device,
 804                                                  size_t policy_hint_size)
 805 {
 806         struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size,
 807                                                        may_format_device, policy_hint_size);
 808
 809         if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
 810                 dm_cache_metadata_close(cmd);
 811                 return ERR_PTR(-EINVAL);
 812         }
 813
 814         return cmd;
 815 }
 816
 817 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 818 {
 819         if (atomic_dec_and_test(&cmd->ref_count)) {
 820                 mutex_lock(&table_lock);
 821                 list_del(&cmd->list);
 822                 mutex_unlock(&table_lock);
 823
 824                 if (!cmd->fail_io)
 825                         __destroy_persistent_data_objects(cmd);
 826                 kfree(cmd);
 827         }
 828 }
 829
 830 /*
 831  * Checks that the given cache block is either unmapped or clean.
 832  */
 833 static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
 834                                    bool *result)
 835 {
 836         int r;
 837         __le64 value;
 838         dm_oblock_t ob;
 839         unsigned flags;
 840
 841         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
 842         if (r) {
 843                 DMERR("block_unmapped_or_clean failed");
 844                 return r;
 845         }
 846
 847         unpack_value(value, &ob, &flags);
 848         *result = !((flags & M_VALID) && (flags & M_DIRTY));
 849
 850         return 0;
 851 }
 852
 853 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 854                                         dm_cblock_t begin, dm_cblock_t end,
 855                                         bool *result)
 856 {
 857         int r;
 858         *result = true;
 859
 860         while (begin != end) {
 861                 r = block_unmapped_or_clean(cmd, begin, result);
 862                 if (r)
 863                         return r;
 864
 865                 if (!*result) {
 866                         DMERR("cache block %llu is dirty",
 867                               (unsigned long long) from_cblock(begin));
 868                         return 0;
 869                 }
 870
 871                 begin = to_cblock(from_cblock(begin) + 1);
 872         }
 873
 874         return 0;
 875 }
 876
 877 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
 878 {
 879         down_write(&cmd->root_lock);
 880         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
 881                 up_write(&cmd->root_lock);
 882                 return false;
 883         }
 884         return true;
 885 }
 886
 887 #define WRITE_LOCK(cmd)                         \
 888         do {                                    \
 889                 if (!cmd_write_lock((cmd)))     \
 890                         return -EINVAL;         \
 891         } while(0)
 892
 893 #define WRITE_LOCK_VOID(cmd)                    \
 894         do {                                    \
 895                 if (!cmd_write_lock((cmd)))     \
 896                         return;                 \
 897         } while(0)
 898
 899 #define WRITE_UNLOCK(cmd) \
 900         up_write(&(cmd)->root_lock)
 901
 902 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
 903 {
 904         down_read(&cmd->root_lock);
 905         if (cmd->fail_io) {
 906                 up_read(&cmd->root_lock);
 907                 return false;
 908         }
 909         return true;
 910 }
 911
 912 #define READ_LOCK(cmd)                          \
 913         do {                                    \
 914                 if (!cmd_read_lock((cmd)))      \
 915                         return -EINVAL;         \
 916         } while(0)
 917
 918 #define READ_LOCK_VOID(cmd)                     \
 919         do {                                    \
 920                 if (!cmd_read_lock((cmd)))      \
 921                         return;                 \
 922         } while(0)
 923
 924 #define READ_UNLOCK(cmd) \
 925         up_read(&(cmd)->root_lock)
 926
 927 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 928 {
 929         int r;
 930         bool clean;
 931         __le64 null_mapping = pack_value(0, 0);
 932
 933         WRITE_LOCK(cmd);
 934         __dm_bless_for_disk(&null_mapping);
 935
 936         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
 937                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
 938                 if (r) {
 939                         __dm_unbless_for_disk(&null_mapping);
 940                         goto out;
 941                 }
 942
 943                 if (!clean) {
 944                         DMERR("unable to shrink cache due to dirty blocks");
 945                         r = -EINVAL;
 946                         __dm_unbless_for_disk(&null_mapping);
 947                         goto out;
 948                 }
 949         }
 950
 951         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
 952                             from_cblock(new_cache_size),
 953                             &null_mapping, &cmd->root);
 954         if (!r)
 955                 cmd->cache_blocks = new_cache_size;
 956         cmd->changed = true;
 957
 958 out:
 959         WRITE_UNLOCK(cmd);
 960
 961         return r;
 962 }
 963
 964 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 965                                    sector_t discard_block_size,
 966                                    dm_dblock_t new_nr_entries)
 967 {
 968         int r;
 969
 970         WRITE_LOCK(cmd);
 971         r = dm_bitset_resize(&cmd->discard_info,
 972                              cmd->discard_root,
 973                              from_dblock(cmd->discard_nr_blocks),
 974                              from_dblock(new_nr_entries),
 975                              false, &cmd->discard_root);
 976         if (!r) {
 977                 cmd->discard_block_size = discard_block_size;
 978                 cmd->discard_nr_blocks = new_nr_entries;
 979         }
 980
 981         cmd->changed = true;
 982         WRITE_UNLOCK(cmd);
 983
 984         return r;
 985 }
 986
 987 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
 988 {
 989         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
 990                                  from_dblock(b), &cmd->discard_root);
 991 }
 992
 993 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
 994 {
 995         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
 996                                    from_dblock(b), &cmd->discard_root);
 997 }
 998
 999 static int __is_discarded(struct dm_cache_metadata *cmd, dm_dblock_t b,
1000                           bool *is_discarded)
1001 {
1002         return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
1003                                   from_dblock(b), &cmd->discard_root,
1004                                   is_discarded);
1005 }
1006
1007 static int __discard(struct dm_cache_metadata *cmd,
1008                      dm_dblock_t dblock, bool discard)
1009 {
1010         int r;
1011
1012         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
1013         if (r)
1014                 return r;
1015
1016         cmd->changed = true;
1017         return 0;
1018 }
1019
1020 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
1021                          dm_dblock_t dblock, bool discard)
1022 {
1023         int r;
1024
1025         WRITE_LOCK(cmd);
1026         r = __discard(cmd, dblock, discard);
1027         WRITE_UNLOCK(cmd);
1028
1029         return r;
1030 }
1031
1032 static int __load_discards(struct dm_cache_metadata *cmd,
1033                            load_discard_fn fn, void *context)
1034 {
1035         int r = 0;
1036         dm_block_t b;
1037         bool discard;
1038
1039         for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1040                 dm_dblock_t dblock = to_dblock(b);
1041
1042                 if (cmd->clean_when_opened) {
1043                         r = __is_discarded(cmd, dblock, &discard);
1044                         if (r)
1045                                 return r;
1046                 } else
1047                         discard = false;
1048
1049                 r = fn(context, cmd->discard_block_size, dblock, discard);
1050                 if (r)
1051                         break;
1052         }
1053
1054         return r;
1055 }
1056
1057 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1058                            load_discard_fn fn, void *context)
1059 {
1060         int r;
1061
1062         READ_LOCK(cmd);
1063         r = __load_discards(cmd, fn, context);
1064         READ_UNLOCK(cmd);
1065
1066         return r;
1067 }
1068
1069 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1070 {
1071         READ_LOCK(cmd);
1072         *result = cmd->cache_blocks;
1073         READ_UNLOCK(cmd);
1074
1075         return 0;
1076 }
1077
1078 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1079 {
1080         int r;
1081         __le64 value = pack_value(0, 0);
1082
1083         __dm_bless_for_disk(&value);
1084         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1085                                &value, &cmd->root);
1086         if (r)
1087                 return r;
1088
1089         cmd->changed = true;
1090         return 0;
1091 }
1092
1093 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1094 {
1095         int r;
1096
1097         WRITE_LOCK(cmd);
1098         r = __remove(cmd, cblock);
1099         WRITE_UNLOCK(cmd);
1100
1101         return r;
1102 }
1103
1104 static int __insert(struct dm_cache_metadata *cmd,
1105                     dm_cblock_t cblock, dm_oblock_t oblock)
1106 {
1107         int r;
1108         __le64 value = pack_value(oblock, M_VALID);
1109         __dm_bless_for_disk(&value);
1110
1111         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1112                                &value, &cmd->root);
1113         if (r)
1114                 return r;
1115
1116         cmd->changed = true;
1117         return 0;
1118 }
1119
1120 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1121                             dm_cblock_t cblock, dm_oblock_t oblock)
1122 {
1123         int r;
1124
1125         WRITE_LOCK(cmd);
1126         r = __insert(cmd, cblock, oblock);
1127         WRITE_UNLOCK(cmd);
1128
1129         return r;
1130 }
1131
1132 struct thunk {
1133         load_mapping_fn fn;
1134         void *context;
1135
1136         struct dm_cache_metadata *cmd;
1137         bool respect_dirty_flags;
1138         bool hints_valid;
1139 };
1140
1141 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1142                              struct dm_cache_policy *policy)
1143 {
1144         const char *policy_name = dm_cache_policy_get_name(policy);
1145         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1146         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1147
1148         /*
1149          * Ensure policy names match.
1150          */
1151         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1152                 return false;
1153
1154         /*
1155          * Ensure policy major versions match.
1156          */
1157         if (cmd->policy_version[0] != policy_version[0])
1158                 return false;
1159
1160         /*
1161          * Ensure policy hint sizes match.
1162          */
1163         if (cmd->policy_hint_size != policy_hint_size)
1164                 return false;
1165
1166         return true;
1167 }
1168
1169 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1170 {
1171         return cmd->hint_root && cmd->policy_hint_size;
1172 }
1173
1174 static bool hints_array_available(struct dm_cache_metadata *cmd,
1175                                   struct dm_cache_policy *policy)
1176 {
1177         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1178                 hints_array_initialized(cmd);
1179 }
1180
1181 static int __load_mapping(struct dm_cache_metadata *cmd,
1182                           uint64_t cb, bool hints_valid,
1183                           struct dm_array_cursor *mapping_cursor,
1184                           struct dm_array_cursor *hint_cursor,
1185                           load_mapping_fn fn, void *context)
1186 {
1187         int r = 0;
1188
1189         __le64 mapping;
1190         __le32 hint = 0;
1191
1192         __le64 *mapping_value_le;
1193         __le32 *hint_value_le;
1194
1195         dm_oblock_t oblock;
1196         unsigned flags;
1197
1198         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1199         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1200         unpack_value(mapping, &oblock, &flags);
1201
1202         if (flags & M_VALID) {
1203                 if (hints_valid) {
1204                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1205                         memcpy(&hint, hint_value_le, sizeof(hint));
1206                 }
1207
1208                 r = fn(context, oblock, to_cblock(cb), flags & M_DIRTY,
1209                        le32_to_cpu(hint), hints_valid);
1210                 if (r)
1211                         DMERR("policy couldn't load cblock");
1212         }
1213
1214         return r;
1215 }
1216
1217 static int __load_mappings(struct dm_cache_metadata *cmd,
1218                            struct dm_cache_policy *policy,
1219                            load_mapping_fn fn, void *context)
1220 {
1221         int r;
1222         uint64_t cb;
1223
1224         bool hints_valid = hints_array_available(cmd, policy);
1225
1226         if (from_cblock(cmd->cache_blocks) == 0)
1227                 /* Nothing to do */
1228                 return 0;
1229
1230         r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1231         if (r)
1232                 return r;
1233
1234         if (hints_valid) {
1235                 r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1236                 if (r) {
1237                         dm_array_cursor_end(&cmd->mapping_cursor);
1238                         return r;
1239                 }
1240         }
1241
1242         for (cb = 0; ; cb++) {
1243                 r = __load_mapping(cmd, cb, hints_valid,
1244                                    &cmd->mapping_cursor, &cmd->hint_cursor,
1245                                    fn, context);
1246                 if (r)
1247                         goto out;
1248
1249                 /*
1250                  * We need to break out before we move the cursors.
1251                  */
1252                 if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1253                         break;
1254
1255                 r = dm_array_cursor_next(&cmd->mapping_cursor);
1256                 if (r) {
1257                         DMERR("dm_array_cursor_next for mapping failed");
1258                         goto out;
1259                 }
1260
1261                 if (hints_valid) {
1262                         r = dm_array_cursor_next(&cmd->hint_cursor);
1263                         if (r) {
1264                                 DMERR("dm_array_cursor_next for hint failed");
1265                                 goto out;
1266                         }
1267                 }
1268         }
1269 out:
1270         dm_array_cursor_end(&cmd->mapping_cursor);
1271         if (hints_valid)
1272                 dm_array_cursor_end(&cmd->hint_cursor);
1273
1274         return r;
1275 }
1276
1277 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1278                            struct dm_cache_policy *policy,
1279                            load_mapping_fn fn, void *context)
1280 {
1281         int r;
1282
1283         READ_LOCK(cmd);
1284         r = __load_mappings(cmd, policy, fn, context);
1285         READ_UNLOCK(cmd);
1286
1287         return r;
1288 }
1289
1290 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1291 {
1292         int r = 0;
1293         __le64 value;
1294         dm_oblock_t oblock;
1295         unsigned flags;
1296
1297         memcpy(&value, leaf, sizeof(value));
1298         unpack_value(value, &oblock, &flags);
1299
1300         return r;
1301 }
1302
1303 static int __dump_mappings(struct dm_cache_metadata *cmd)
1304 {
1305         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1306 }
1307
1308 void dm_cache_dump(struct dm_cache_metadata *cmd)
1309 {
1310         READ_LOCK_VOID(cmd);
1311         __dump_mappings(cmd);
1312         READ_UNLOCK(cmd);
1313 }
1314
1315 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1316 {
1317         int r;
1318
1319         READ_LOCK(cmd);
1320         r = cmd->changed;
1321         READ_UNLOCK(cmd);
1322
1323         return r;
1324 }
1325
1326 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1327 {
1328         int r;
1329         unsigned flags;
1330         dm_oblock_t oblock;
1331         __le64 value;
1332
1333         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1334         if (r)
1335                 return r;
1336
1337         unpack_value(value, &oblock, &flags);
1338
1339         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1340                 /* nothing to be done */
1341                 return 0;
1342
1343         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1344         __dm_bless_for_disk(&value);
1345
1346         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1347                                &value, &cmd->root);
1348         if (r)
1349                 return r;
1350
1351         cmd->changed = true;
1352         return 0;
1353
1354 }
1355
1356 int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
1357                        dm_cblock_t cblock, bool dirty)
1358 {
1359         int r;
1360
1361         WRITE_LOCK(cmd);
1362         r = __dirty(cmd, cblock, dirty);
1363         WRITE_UNLOCK(cmd);
1364
1365         return r;
1366 }
1367
1368 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1369                                  struct dm_cache_statistics *stats)
1370 {
1371         READ_LOCK_VOID(cmd);
1372         *stats = cmd->stats;
1373         READ_UNLOCK(cmd);
1374 }
1375
1376 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1377                                  struct dm_cache_statistics *stats)
1378 {
1379         WRITE_LOCK_VOID(cmd);
1380         cmd->stats = *stats;
1381         WRITE_UNLOCK(cmd);
1382 }
1383
1384 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1385 {
1386         int r;
1387         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1388                                  clear_clean_shutdown);
1389
1390         WRITE_LOCK(cmd);
1391         r = __commit_transaction(cmd, mutator);
1392         if (r)
1393                 goto out;
1394
1395         r = __begin_transaction(cmd);
1396
1397 out:
1398         WRITE_UNLOCK(cmd);
1399         return r;
1400 }
1401
1402 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1403                                            dm_block_t *result)
1404 {
1405         int r = -EINVAL;
1406
1407         READ_LOCK(cmd);
1408         r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1409         READ_UNLOCK(cmd);
1410
1411         return r;
1412 }
1413
1414 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1415                                    dm_block_t *result)
1416 {
1417         int r = -EINVAL;
1418
1419         READ_LOCK(cmd);
1420         r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1421         READ_UNLOCK(cmd);
1422
1423         return r;
1424 }
1425
1426 /*----------------------------------------------------------------*/
1427
1428 static int get_hint(uint32_t index, void *value_le, void *context)
1429 {
1430         uint32_t value;
1431         struct dm_cache_policy *policy = context;
1432
1433         value = policy_get_hint(policy, to_cblock(index));
1434         *((__le32 *) value_le) = cpu_to_le32(value);
1435
1436         return 0;
1437 }
1438
1439 /*
1440  * It's quicker to always delete the hint array, and recreate with
1441  * dm_array_new().
1442  */
1443 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1444 {
1445         int r;
1446         size_t hint_size;
1447         const char *policy_name = dm_cache_policy_get_name(policy);
1448         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1449
1450         if (!policy_name[0] ||
1451             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1452                 return -EINVAL;
1453
1454         strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1455         memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1456
1457         hint_size = dm_cache_policy_get_hint_size(policy);
1458         if (!hint_size)
1459                 return 0; /* short-circuit hints initialization */
1460         cmd->policy_hint_size = hint_size;
1461
1462         if (cmd->hint_root) {
1463                 r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1464                 if (r)
1465                         return r;
1466         }
1467
1468         return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1469                             from_cblock(cmd->cache_blocks),
1470                             get_hint, policy);
1471 }
1472
1473 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1474 {
1475         int r;
1476
1477         WRITE_LOCK(cmd);
1478         r = write_hints(cmd, policy);
1479         WRITE_UNLOCK(cmd);
1480
1481         return r;
1482 }
1483
1484 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1485 {
1486         int r;
1487
1488         READ_LOCK(cmd);
1489         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1490         READ_UNLOCK(cmd);
1491
1492         return r;
1493 }
1494
1495 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1496 {
1497         WRITE_LOCK_VOID(cmd);
1498         dm_bm_set_read_only(cmd->bm);
1499         WRITE_UNLOCK(cmd);
1500 }
1501
1502 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1503 {
1504         WRITE_LOCK_VOID(cmd);
1505         dm_bm_set_read_write(cmd->bm);
1506         WRITE_UNLOCK(cmd);
1507 }
1508
1509 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1510 {
1511         int r;
1512         struct dm_block *sblock;
1513         struct cache_disk_superblock *disk_super;
1514
1515         WRITE_LOCK(cmd);
1516         set_bit(NEEDS_CHECK, &cmd->flags);
1517
1518         r = superblock_lock(cmd, &sblock);
1519         if (r) {
1520                 DMERR("couldn't read superblock");
1521                 goto out;
1522         }
1523
1524         disk_super = dm_block_data(sblock);
1525         disk_super->flags = cpu_to_le32(cmd->flags);
1526
1527         dm_bm_unlock(sblock);
1528
1529 out:
1530         WRITE_UNLOCK(cmd);
1531         return r;
1532 }
1533
1534 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1535 {
1536         READ_LOCK(cmd);
1537         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1538         READ_UNLOCK(cmd);
1539
1540         return 0;
1541 }
1542
1543 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1544 {
1545         int r;
1546
1547         WRITE_LOCK(cmd);
1548         __destroy_persistent_data_objects(cmd);
1549         r = __create_persistent_data_objects(cmd, false);
1550         if (r)
1551                 cmd->fail_io = true;
1552         WRITE_UNLOCK(cmd);
1553
1554         return r;
1555 }