drivers/md/dm-cache-metadata.c

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