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         r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
 934                                    from_cblock(cmd->cache_blocks), &cmd->dirty_cursor);
 935         if (r) {
 936                 DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__);
 937                 return r;
 938         }
 939
 940         r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin));
 941         if (r) {
 942                 DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__);
 943                 dm_bitset_cursor_end(&cmd->dirty_cursor);
 944                 return r;
 945         }
 946
 947         while (begin != end) {
 948                 /*
 949                  * We assume that unmapped blocks have their dirty bit
 950                  * cleared.
 951                  */
 952                 dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor);
 953                 if (dirty_flag) {
 954                         DMERR("%s: cache block %llu is dirty", __func__,
 955                               (unsigned long long) from_cblock(begin));
 956                         dm_bitset_cursor_end(&cmd->dirty_cursor);
 957                         *result = false;
 958                         return 0;
 959                 }
 960
 961                 begin = to_cblock(from_cblock(begin) + 1);
 962                 if (begin == end)
 963                         break;
 964
 965                 r = dm_bitset_cursor_next(&cmd->dirty_cursor);
 966                 if (r) {
 967                         DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__);
 968                         dm_bitset_cursor_end(&cmd->dirty_cursor);
 969                         return r;
 970                 }
 971         }
 972
 973         dm_bitset_cursor_end(&cmd->dirty_cursor);
 974
 975         return 0;
 976 }
 977
 978 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 979                                         dm_cblock_t begin, dm_cblock_t end,
 980                                         bool *result)
 981 {
 982         if (separate_dirty_bits(cmd))
 983                 return blocks_are_clean_separate_dirty(cmd, begin, end, result);
 984         else
 985                 return blocks_are_clean_combined_dirty(cmd, begin, end, result);
 986 }
 987
 988 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
 989 {
 990         down_write(&cmd->root_lock);
 991         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
 992                 up_write(&cmd->root_lock);
 993                 return false;
 994         }
 995         return true;
 996 }
 997
 998 #define WRITE_LOCK(cmd)                         \
 999         do {                                    \
1000                 if (!cmd_write_lock((cmd)))     \
1001                         return -EINVAL;         \
1002         } while(0)
1003
1004 #define WRITE_LOCK_VOID(cmd)                    \
1005         do {                                    \
1006                 if (!cmd_write_lock((cmd)))     \
1007                         return;                 \
1008         } while(0)
1009
1010 #define WRITE_UNLOCK(cmd) \
1011         up_write(&(cmd)->root_lock)
1012
1013 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
1014 {
1015         down_read(&cmd->root_lock);
1016         if (cmd->fail_io) {
1017                 up_read(&cmd->root_lock);
1018                 return false;
1019         }
1020         return true;
1021 }
1022
1023 #define READ_LOCK(cmd)                          \
1024         do {                                    \
1025                 if (!cmd_read_lock((cmd)))      \
1026                         return -EINVAL;         \
1027         } while(0)
1028
1029 #define READ_LOCK_VOID(cmd)                     \
1030         do {                                    \
1031                 if (!cmd_read_lock((cmd)))      \
1032                         return;                 \
1033         } while(0)
1034
1035 #define READ_UNLOCK(cmd) \
1036         up_read(&(cmd)->root_lock)
1037
1038 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
1039 {
1040         int r;
1041         bool clean;
1042         __le64 null_mapping = pack_value(0, 0);
1043
1044         WRITE_LOCK(cmd);
1045         __dm_bless_for_disk(&null_mapping);
1046
1047         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
1048                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
1049                 if (r) {
1050                         __dm_unbless_for_disk(&null_mapping);
1051                         goto out;
1052                 }
1053
1054                 if (!clean) {
1055                         DMERR("unable to shrink cache due to dirty blocks");
1056                         r = -EINVAL;
1057                         __dm_unbless_for_disk(&null_mapping);
1058                         goto out;
1059                 }
1060         }
1061
1062         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
1063                             from_cblock(new_cache_size),
1064                             &null_mapping, &cmd->root);
1065         if (r)
1066                 goto out;
1067
1068         if (separate_dirty_bits(cmd)) {
1069                 r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root,
1070                                      from_cblock(cmd->cache_blocks), from_cblock(new_cache_size),
1071                                      false, &cmd->dirty_root);
1072                 if (r)
1073                         goto out;
1074         }
1075
1076         cmd->cache_blocks = new_cache_size;
1077         cmd->changed = true;
1078
1079 out:
1080         WRITE_UNLOCK(cmd);
1081
1082         return r;
1083 }
1084
1085 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
1086                                    sector_t discard_block_size,
1087                                    dm_dblock_t new_nr_entries)
1088 {
1089         int r;
1090
1091         WRITE_LOCK(cmd);
1092         r = dm_bitset_resize(&cmd->discard_info,
1093                              cmd->discard_root,
1094                              from_dblock(cmd->discard_nr_blocks),
1095                              from_dblock(new_nr_entries),
1096                              false, &cmd->discard_root);
1097         if (!r) {
1098                 cmd->discard_block_size = discard_block_size;
1099                 cmd->discard_nr_blocks = new_nr_entries;
1100         }
1101
1102         cmd->changed = true;
1103         WRITE_UNLOCK(cmd);
1104
1105         return r;
1106 }
1107
1108 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1109 {
1110         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
1111                                  from_dblock(b), &cmd->discard_root);
1112 }
1113
1114 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1115 {
1116         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
1117                                    from_dblock(b), &cmd->discard_root);
1118 }
1119
1120 static int __discard(struct dm_cache_metadata *cmd,
1121                      dm_dblock_t dblock, bool discard)
1122 {
1123         int r;
1124
1125         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
1126         if (r)
1127                 return r;
1128
1129         cmd->changed = true;
1130         return 0;
1131 }
1132
1133 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
1134                          dm_dblock_t dblock, bool discard)
1135 {
1136         int r;
1137
1138         WRITE_LOCK(cmd);
1139         r = __discard(cmd, dblock, discard);
1140         WRITE_UNLOCK(cmd);
1141
1142         return r;
1143 }
1144
1145 static int __load_discards(struct dm_cache_metadata *cmd,
1146                            load_discard_fn fn, void *context)
1147 {
1148         int r = 0;
1149         uint32_t b;
1150         struct dm_bitset_cursor c;
1151
1152         if (from_dblock(cmd->discard_nr_blocks) == 0)
1153                 /* nothing to do */
1154                 return 0;
1155
1156         if (cmd->clean_when_opened) {
1157                 r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root);
1158                 if (r)
1159                         return r;
1160
1161                 r = dm_bitset_cursor_begin(&cmd->discard_info, cmd->discard_root,
1162                                            from_dblock(cmd->discard_nr_blocks), &c);
1163                 if (r)
1164                         return r;
1165
1166                 for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1167                         r = fn(context, cmd->discard_block_size, to_dblock(b),
1168                                dm_bitset_cursor_get_value(&c));
1169                         if (r)
1170                                 break;
1171                 }
1172
1173                 dm_bitset_cursor_end(&c);
1174
1175         } else {
1176                 for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1177                         r = fn(context, cmd->discard_block_size, to_dblock(b), false);
1178                         if (r)
1179                                 return r;
1180                 }
1181         }
1182
1183         return r;
1184 }
1185
1186 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1187                            load_discard_fn fn, void *context)
1188 {
1189         int r;
1190
1191         READ_LOCK(cmd);
1192         r = __load_discards(cmd, fn, context);
1193         READ_UNLOCK(cmd);
1194
1195         return r;
1196 }
1197
1198 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1199 {
1200         READ_LOCK(cmd);
1201         *result = cmd->cache_blocks;
1202         READ_UNLOCK(cmd);
1203
1204         return 0;
1205 }
1206
1207 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1208 {
1209         int r;
1210         __le64 value = pack_value(0, 0);
1211
1212         __dm_bless_for_disk(&value);
1213         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1214                                &value, &cmd->root);
1215         if (r)
1216                 return r;
1217
1218         cmd->changed = true;
1219         return 0;
1220 }
1221
1222 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1223 {
1224         int r;
1225
1226         WRITE_LOCK(cmd);
1227         r = __remove(cmd, cblock);
1228         WRITE_UNLOCK(cmd);
1229
1230         return r;
1231 }
1232
1233 static int __insert(struct dm_cache_metadata *cmd,
1234                     dm_cblock_t cblock, dm_oblock_t oblock)
1235 {
1236         int r;
1237         __le64 value = pack_value(oblock, M_VALID);
1238         __dm_bless_for_disk(&value);
1239
1240         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1241                                &value, &cmd->root);
1242         if (r)
1243                 return r;
1244
1245         cmd->changed = true;
1246         return 0;
1247 }
1248
1249 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1250                             dm_cblock_t cblock, dm_oblock_t oblock)
1251 {
1252         int r;
1253
1254         WRITE_LOCK(cmd);
1255         r = __insert(cmd, cblock, oblock);
1256         WRITE_UNLOCK(cmd);
1257
1258         return r;
1259 }
1260
1261 struct thunk {
1262         load_mapping_fn fn;
1263         void *context;
1264
1265         struct dm_cache_metadata *cmd;
1266         bool respect_dirty_flags;
1267         bool hints_valid;
1268 };
1269
1270 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1271                              struct dm_cache_policy *policy)
1272 {
1273         const char *policy_name = dm_cache_policy_get_name(policy);
1274         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1275         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1276
1277         /*
1278          * Ensure policy names match.
1279          */
1280         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1281                 return false;
1282
1283         /*
1284          * Ensure policy major versions match.
1285          */
1286         if (cmd->policy_version[0] != policy_version[0])
1287                 return false;
1288
1289         /*
1290          * Ensure policy hint sizes match.
1291          */
1292         if (cmd->policy_hint_size != policy_hint_size)
1293                 return false;
1294
1295         return true;
1296 }
1297
1298 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1299 {
1300         return cmd->hint_root && cmd->policy_hint_size;
1301 }
1302
1303 static bool hints_array_available(struct dm_cache_metadata *cmd,
1304                                   struct dm_cache_policy *policy)
1305 {
1306         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1307                 hints_array_initialized(cmd);
1308 }
1309
1310 static int __load_mapping_v1(struct dm_cache_metadata *cmd,
1311                              uint64_t cb, bool hints_valid,
1312                              struct dm_array_cursor *mapping_cursor,
1313                              struct dm_array_cursor *hint_cursor,
1314                              load_mapping_fn fn, void *context)
1315 {
1316         int r = 0;
1317
1318         __le64 mapping;
1319         __le32 hint = 0;
1320
1321         __le64 *mapping_value_le;
1322         __le32 *hint_value_le;
1323
1324         dm_oblock_t oblock;
1325         unsigned flags;
1326         bool dirty = true;
1327
1328         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1329         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1330         unpack_value(mapping, &oblock, &flags);
1331
1332         if (flags & M_VALID) {
1333                 if (hints_valid) {
1334                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1335                         memcpy(&hint, hint_value_le, sizeof(hint));
1336                 }
1337                 if (cmd->clean_when_opened)
1338                         dirty = flags & M_DIRTY;
1339
1340                 r = fn(context, oblock, to_cblock(cb), dirty,
1341                        le32_to_cpu(hint), hints_valid);
1342                 if (r) {
1343                         DMERR("policy couldn't load cache block %llu",
1344                               (unsigned long long) from_cblock(to_cblock(cb)));
1345                 }
1346         }
1347
1348         return r;
1349 }
1350
1351 static int __load_mapping_v2(struct dm_cache_metadata *cmd,
1352                              uint64_t cb, bool hints_valid,
1353                              struct dm_array_cursor *mapping_cursor,
1354                              struct dm_array_cursor *hint_cursor,
1355                              struct dm_bitset_cursor *dirty_cursor,
1356                              load_mapping_fn fn, void *context)
1357 {
1358         int r = 0;
1359
1360         __le64 mapping;
1361         __le32 hint = 0;
1362
1363         __le64 *mapping_value_le;
1364         __le32 *hint_value_le;
1365
1366         dm_oblock_t oblock;
1367         unsigned flags;
1368         bool dirty = true;
1369
1370         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1371         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1372         unpack_value(mapping, &oblock, &flags);
1373
1374         if (flags & M_VALID) {
1375                 if (hints_valid) {
1376                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1377                         memcpy(&hint, hint_value_le, sizeof(hint));
1378                 }
1379                 if (cmd->clean_when_opened)
1380                         dirty = dm_bitset_cursor_get_value(dirty_cursor);
1381
1382                 r = fn(context, oblock, to_cblock(cb), dirty,
1383                        le32_to_cpu(hint), hints_valid);
1384                 if (r) {
1385                         DMERR("policy couldn't load cache block %llu",
1386                               (unsigned long long) from_cblock(to_cblock(cb)));
1387                 }
1388         }
1389
1390         return r;
1391 }
1392
1393 static int __load_mappings(struct dm_cache_metadata *cmd,
1394                            struct dm_cache_policy *policy,
1395                            load_mapping_fn fn, void *context)
1396 {
1397         int r;
1398         uint64_t cb;
1399
1400         bool hints_valid = hints_array_available(cmd, policy);
1401
1402         if (from_cblock(cmd->cache_blocks) == 0)
1403                 /* Nothing to do */
1404                 return 0;
1405
1406         r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1407         if (r)
1408                 return r;
1409
1410         if (hints_valid) {
1411                 r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1412                 if (r) {
1413                         dm_array_cursor_end(&cmd->mapping_cursor);
1414                         return r;
1415                 }
1416         }
1417
1418         if (separate_dirty_bits(cmd)) {
1419                 r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
1420                                            from_cblock(cmd->cache_blocks),
1421                                            &cmd->dirty_cursor);
1422                 if (r) {
1423                         dm_array_cursor_end(&cmd->hint_cursor);
1424                         dm_array_cursor_end(&cmd->mapping_cursor);
1425                         return r;
1426                 }
1427         }
1428
1429         for (cb = 0; ; cb++) {
1430                 if (separate_dirty_bits(cmd))
1431                         r = __load_mapping_v2(cmd, cb, hints_valid,
1432                                               &cmd->mapping_cursor,
1433                                               &cmd->hint_cursor,
1434                                               &cmd->dirty_cursor,
1435                                               fn, context);
1436                 else
1437                         r = __load_mapping_v1(cmd, cb, hints_valid,
1438                                               &cmd->mapping_cursor, &cmd->hint_cursor,
1439                                               fn, context);
1440                 if (r)
1441                         goto out;
1442
1443                 /*
1444                  * We need to break out before we move the cursors.
1445                  */
1446                 if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1447                         break;
1448
1449                 r = dm_array_cursor_next(&cmd->mapping_cursor);
1450                 if (r) {
1451                         DMERR("dm_array_cursor_next for mapping failed");
1452                         goto out;
1453                 }
1454
1455                 if (hints_valid) {
1456                         r = dm_array_cursor_next(&cmd->hint_cursor);
1457                         if (r) {
1458                                 dm_array_cursor_end(&cmd->hint_cursor);
1459                                 hints_valid = false;
1460                         }
1461                 }
1462
1463                 if (separate_dirty_bits(cmd)) {
1464                         r = dm_bitset_cursor_next(&cmd->dirty_cursor);
1465                         if (r) {
1466                                 DMERR("dm_bitset_cursor_next for dirty failed");
1467                                 goto out;
1468                         }
1469                 }
1470         }
1471 out:
1472         dm_array_cursor_end(&cmd->mapping_cursor);
1473         if (hints_valid)
1474                 dm_array_cursor_end(&cmd->hint_cursor);
1475
1476         if (separate_dirty_bits(cmd))
1477                 dm_bitset_cursor_end(&cmd->dirty_cursor);
1478
1479         return r;
1480 }
1481
1482 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1483                            struct dm_cache_policy *policy,
1484                            load_mapping_fn fn, void *context)
1485 {
1486         int r;
1487
1488         READ_LOCK(cmd);
1489         r = __load_mappings(cmd, policy, fn, context);
1490         READ_UNLOCK(cmd);
1491
1492         return r;
1493 }
1494
1495 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1496 {
1497         int r = 0;
1498         __le64 value;
1499         dm_oblock_t oblock;
1500         unsigned flags;
1501
1502         memcpy(&value, leaf, sizeof(value));
1503         unpack_value(value, &oblock, &flags);
1504
1505         return r;
1506 }
1507
1508 static int __dump_mappings(struct dm_cache_metadata *cmd)
1509 {
1510         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1511 }
1512
1513 void dm_cache_dump(struct dm_cache_metadata *cmd)
1514 {
1515         READ_LOCK_VOID(cmd);
1516         __dump_mappings(cmd);
1517         READ_UNLOCK(cmd);
1518 }
1519
1520 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1521 {
1522         int r;
1523
1524         READ_LOCK(cmd);
1525         r = cmd->changed;
1526         READ_UNLOCK(cmd);
1527
1528         return r;
1529 }
1530
1531 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1532 {
1533         int r;
1534         unsigned flags;
1535         dm_oblock_t oblock;
1536         __le64 value;
1537
1538         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1539         if (r)
1540                 return r;
1541
1542         unpack_value(value, &oblock, &flags);
1543
1544         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1545                 /* nothing to be done */
1546                 return 0;
1547
1548         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1549         __dm_bless_for_disk(&value);
1550
1551         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1552                                &value, &cmd->root);
1553         if (r)
1554                 return r;
1555
1556         cmd->changed = true;
1557         return 0;
1558
1559 }
1560
1561 static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1562 {
1563         int r;
1564         unsigned i;
1565         for (i = 0; i < nr_bits; i++) {
1566                 r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
1567                 if (r)
1568                         return r;
1569         }
1570
1571         return 0;
1572 }
1573
1574 static int is_dirty_callback(uint32_t index, bool *value, void *context)
1575 {
1576         unsigned long *bits = context;
1577         *value = test_bit(index, bits);
1578         return 0;
1579 }
1580
1581 static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1582 {
1583         int r = 0;
1584
1585         /* nr_bits is really just a sanity check */
1586         if (nr_bits != from_cblock(cmd->cache_blocks)) {
1587                 DMERR("dirty bitset is wrong size");
1588                 return -EINVAL;
1589         }
1590
1591         r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root);
1592         if (r)
1593                 return r;
1594
1595         cmd->changed = true;
1596         return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits);
1597 }
1598
1599 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
1600                             unsigned nr_bits,
1601                             unsigned long *bits)
1602 {
1603         int r;
1604
1605         WRITE_LOCK(cmd);
1606         if (separate_dirty_bits(cmd))
1607                 r = __set_dirty_bits_v2(cmd, nr_bits, bits);
1608         else
1609                 r = __set_dirty_bits_v1(cmd, nr_bits, bits);
1610         WRITE_UNLOCK(cmd);
1611
1612         return r;
1613 }
1614
1615 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1616                                  struct dm_cache_statistics *stats)
1617 {
1618         READ_LOCK_VOID(cmd);
1619         *stats = cmd->stats;
1620         READ_UNLOCK(cmd);
1621 }
1622
1623 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1624                                  struct dm_cache_statistics *stats)
1625 {
1626         WRITE_LOCK_VOID(cmd);
1627         cmd->stats = *stats;
1628         WRITE_UNLOCK(cmd);
1629 }
1630
1631 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1632 {
1633         int r = -EINVAL;
1634         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1635                                  clear_clean_shutdown);
1636
1637         WRITE_LOCK(cmd);
1638         if (cmd->fail_io)
1639                 goto out;
1640
1641         r = __commit_transaction(cmd, mutator);
1642         if (r)
1643                 goto out;
1644
1645         r = __begin_transaction(cmd);
1646 out:
1647         WRITE_UNLOCK(cmd);
1648         return r;
1649 }
1650
1651 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1652                                            dm_block_t *result)
1653 {
1654         int r = -EINVAL;
1655
1656         READ_LOCK(cmd);
1657         if (!cmd->fail_io)
1658                 r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1659         READ_UNLOCK(cmd);
1660
1661         return r;
1662 }
1663
1664 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1665                                    dm_block_t *result)
1666 {
1667         int r = -EINVAL;
1668
1669         READ_LOCK(cmd);
1670         if (!cmd->fail_io)
1671                 r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1672         READ_UNLOCK(cmd);
1673
1674         return r;
1675 }
1676
1677 /*----------------------------------------------------------------*/
1678
1679 static int get_hint(uint32_t index, void *value_le, void *context)
1680 {
1681         uint32_t value;
1682         struct dm_cache_policy *policy = context;
1683
1684         value = policy_get_hint(policy, to_cblock(index));
1685         *((__le32 *) value_le) = cpu_to_le32(value);
1686
1687         return 0;
1688 }
1689
1690 /*
1691  * It's quicker to always delete the hint array, and recreate with
1692  * dm_array_new().
1693  */
1694 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1695 {
1696         int r;
1697         size_t hint_size;
1698         const char *policy_name = dm_cache_policy_get_name(policy);
1699         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1700
1701         if (!policy_name[0] ||
1702             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1703                 return -EINVAL;
1704
1705         strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1706         memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1707
1708         hint_size = dm_cache_policy_get_hint_size(policy);
1709         if (!hint_size)
1710                 return 0; /* short-circuit hints initialization */
1711         cmd->policy_hint_size = hint_size;
1712
1713         if (cmd->hint_root) {
1714                 r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1715                 if (r)
1716                         return r;
1717         }
1718
1719         return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1720                             from_cblock(cmd->cache_blocks),
1721                             get_hint, policy);
1722 }
1723
1724 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1725 {
1726         int r;
1727
1728         WRITE_LOCK(cmd);
1729         r = write_hints(cmd, policy);
1730         WRITE_UNLOCK(cmd);
1731
1732         return r;
1733 }
1734
1735 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1736 {
1737         int r;
1738
1739         READ_LOCK(cmd);
1740         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1741         READ_UNLOCK(cmd);
1742
1743         return r;
1744 }
1745
1746 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1747 {
1748         WRITE_LOCK_VOID(cmd);
1749         dm_bm_set_read_only(cmd->bm);
1750         WRITE_UNLOCK(cmd);
1751 }
1752
1753 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1754 {
1755         WRITE_LOCK_VOID(cmd);
1756         dm_bm_set_read_write(cmd->bm);
1757         WRITE_UNLOCK(cmd);
1758 }
1759
1760 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1761 {
1762         int r;
1763         struct dm_block *sblock;
1764         struct cache_disk_superblock *disk_super;
1765
1766         WRITE_LOCK(cmd);
1767         set_bit(NEEDS_CHECK, &cmd->flags);
1768
1769         r = superblock_lock(cmd, &sblock);
1770         if (r) {
1771                 DMERR("couldn't read superblock");
1772                 goto out;
1773         }
1774
1775         disk_super = dm_block_data(sblock);
1776         disk_super->flags = cpu_to_le32(cmd->flags);
1777
1778         dm_bm_unlock(sblock);
1779
1780 out:
1781         WRITE_UNLOCK(cmd);
1782         return r;
1783 }
1784
1785 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1786 {
1787         READ_LOCK(cmd);
1788         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1789         READ_UNLOCK(cmd);
1790
1791         return 0;
1792 }
1793
1794 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1795 {
1796         int r;
1797
1798         WRITE_LOCK(cmd);
1799         __destroy_persistent_data_objects(cmd);
1800         r = __create_persistent_data_objects(cmd, false);
1801         if (r)
1802                 cmd->fail_io = true;
1803         WRITE_UNLOCK(cmd);
1804
1805         return r;
1806 }