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++) {
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                         if (b >= (from_dblock(cmd->discard_nr_blocks) - 1))
1177                                 break;
1178
1179                         r = dm_bitset_cursor_next(&c);
1180                         if (r)
1181                                 break;
1182                 }
1183
1184                 dm_bitset_cursor_end(&c);
1185
1186         } else {
1187                 for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1188                         r = fn(context, cmd->discard_block_size, to_dblock(b), false);
1189                         if (r)
1190                                 return r;
1191                 }
1192         }
1193
1194         return r;
1195 }
1196
1197 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1198                            load_discard_fn fn, void *context)
1199 {
1200         int r;
1201
1202         READ_LOCK(cmd);
1203         r = __load_discards(cmd, fn, context);
1204         READ_UNLOCK(cmd);
1205
1206         return r;
1207 }
1208
1209 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1210 {
1211         READ_LOCK(cmd);
1212         *result = cmd->cache_blocks;
1213         READ_UNLOCK(cmd);
1214
1215         return 0;
1216 }
1217
1218 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1219 {
1220         int r;
1221         __le64 value = pack_value(0, 0);
1222
1223         __dm_bless_for_disk(&value);
1224         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1225                                &value, &cmd->root);
1226         if (r)
1227                 return r;
1228
1229         cmd->changed = true;
1230         return 0;
1231 }
1232
1233 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1234 {
1235         int r;
1236
1237         WRITE_LOCK(cmd);
1238         r = __remove(cmd, cblock);
1239         WRITE_UNLOCK(cmd);
1240
1241         return r;
1242 }
1243
1244 static int __insert(struct dm_cache_metadata *cmd,
1245                     dm_cblock_t cblock, dm_oblock_t oblock)
1246 {
1247         int r;
1248         __le64 value = pack_value(oblock, M_VALID);
1249         __dm_bless_for_disk(&value);
1250
1251         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1252                                &value, &cmd->root);
1253         if (r)
1254                 return r;
1255
1256         cmd->changed = true;
1257         return 0;
1258 }
1259
1260 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1261                             dm_cblock_t cblock, dm_oblock_t oblock)
1262 {
1263         int r;
1264
1265         WRITE_LOCK(cmd);
1266         r = __insert(cmd, cblock, oblock);
1267         WRITE_UNLOCK(cmd);
1268
1269         return r;
1270 }
1271
1272 struct thunk {
1273         load_mapping_fn fn;
1274         void *context;
1275
1276         struct dm_cache_metadata *cmd;
1277         bool respect_dirty_flags;
1278         bool hints_valid;
1279 };
1280
1281 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1282                              struct dm_cache_policy *policy)
1283 {
1284         const char *policy_name = dm_cache_policy_get_name(policy);
1285         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1286         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1287
1288         /*
1289          * Ensure policy names match.
1290          */
1291         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1292                 return false;
1293
1294         /*
1295          * Ensure policy major versions match.
1296          */
1297         if (cmd->policy_version[0] != policy_version[0])
1298                 return false;
1299
1300         /*
1301          * Ensure policy hint sizes match.
1302          */
1303         if (cmd->policy_hint_size != policy_hint_size)
1304                 return false;
1305
1306         return true;
1307 }
1308
1309 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1310 {
1311         return cmd->hint_root && cmd->policy_hint_size;
1312 }
1313
1314 static bool hints_array_available(struct dm_cache_metadata *cmd,
1315                                   struct dm_cache_policy *policy)
1316 {
1317         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1318                 hints_array_initialized(cmd);
1319 }
1320
1321 static int __load_mapping_v1(struct dm_cache_metadata *cmd,
1322                              uint64_t cb, bool hints_valid,
1323                              struct dm_array_cursor *mapping_cursor,
1324                              struct dm_array_cursor *hint_cursor,
1325                              load_mapping_fn fn, void *context)
1326 {
1327         int r = 0;
1328
1329         __le64 mapping;
1330         __le32 hint = 0;
1331
1332         __le64 *mapping_value_le;
1333         __le32 *hint_value_le;
1334
1335         dm_oblock_t oblock;
1336         unsigned flags;
1337         bool dirty = true;
1338
1339         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1340         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1341         unpack_value(mapping, &oblock, &flags);
1342
1343         if (flags & M_VALID) {
1344                 if (hints_valid) {
1345                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1346                         memcpy(&hint, hint_value_le, sizeof(hint));
1347                 }
1348                 if (cmd->clean_when_opened)
1349                         dirty = flags & M_DIRTY;
1350
1351                 r = fn(context, oblock, to_cblock(cb), dirty,
1352                        le32_to_cpu(hint), hints_valid);
1353                 if (r) {
1354                         DMERR("policy couldn't load cache block %llu",
1355                               (unsigned long long) from_cblock(to_cblock(cb)));
1356                 }
1357         }
1358
1359         return r;
1360 }
1361
1362 static int __load_mapping_v2(struct dm_cache_metadata *cmd,
1363                              uint64_t cb, bool hints_valid,
1364                              struct dm_array_cursor *mapping_cursor,
1365                              struct dm_array_cursor *hint_cursor,
1366                              struct dm_bitset_cursor *dirty_cursor,
1367                              load_mapping_fn fn, void *context)
1368 {
1369         int r = 0;
1370
1371         __le64 mapping;
1372         __le32 hint = 0;
1373
1374         __le64 *mapping_value_le;
1375         __le32 *hint_value_le;
1376
1377         dm_oblock_t oblock;
1378         unsigned flags;
1379         bool dirty = true;
1380
1381         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1382         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1383         unpack_value(mapping, &oblock, &flags);
1384
1385         if (flags & M_VALID) {
1386                 if (hints_valid) {
1387                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1388                         memcpy(&hint, hint_value_le, sizeof(hint));
1389                 }
1390                 if (cmd->clean_when_opened)
1391                         dirty = dm_bitset_cursor_get_value(dirty_cursor);
1392
1393                 r = fn(context, oblock, to_cblock(cb), dirty,
1394                        le32_to_cpu(hint), hints_valid);
1395                 if (r) {
1396                         DMERR("policy couldn't load cache block %llu",
1397                               (unsigned long long) from_cblock(to_cblock(cb)));
1398                 }
1399         }
1400
1401         return r;
1402 }
1403
1404 static int __load_mappings(struct dm_cache_metadata *cmd,
1405                            struct dm_cache_policy *policy,
1406                            load_mapping_fn fn, void *context)
1407 {
1408         int r;
1409         uint64_t cb;
1410
1411         bool hints_valid = hints_array_available(cmd, policy);
1412
1413         if (from_cblock(cmd->cache_blocks) == 0)
1414                 /* Nothing to do */
1415                 return 0;
1416
1417         r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1418         if (r)
1419                 return r;
1420
1421         if (hints_valid) {
1422                 r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1423                 if (r) {
1424                         dm_array_cursor_end(&cmd->mapping_cursor);
1425                         return r;
1426                 }
1427         }
1428
1429         if (separate_dirty_bits(cmd)) {
1430                 r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
1431                                            from_cblock(cmd->cache_blocks),
1432                                            &cmd->dirty_cursor);
1433                 if (r) {
1434                         dm_array_cursor_end(&cmd->hint_cursor);
1435                         dm_array_cursor_end(&cmd->mapping_cursor);
1436                         return r;
1437                 }
1438         }
1439
1440         for (cb = 0; ; cb++) {
1441                 if (separate_dirty_bits(cmd))
1442                         r = __load_mapping_v2(cmd, cb, hints_valid,
1443                                               &cmd->mapping_cursor,
1444                                               &cmd->hint_cursor,
1445                                               &cmd->dirty_cursor,
1446                                               fn, context);
1447                 else
1448                         r = __load_mapping_v1(cmd, cb, hints_valid,
1449                                               &cmd->mapping_cursor, &cmd->hint_cursor,
1450                                               fn, context);
1451                 if (r)
1452                         goto out;
1453
1454                 /*
1455                  * We need to break out before we move the cursors.
1456                  */
1457                 if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1458                         break;
1459
1460                 r = dm_array_cursor_next(&cmd->mapping_cursor);
1461                 if (r) {
1462                         DMERR("dm_array_cursor_next for mapping failed");
1463                         goto out;
1464                 }
1465
1466                 if (hints_valid) {
1467                         r = dm_array_cursor_next(&cmd->hint_cursor);
1468                         if (r) {
1469                                 dm_array_cursor_end(&cmd->hint_cursor);
1470                                 hints_valid = false;
1471                         }
1472                 }
1473
1474                 if (separate_dirty_bits(cmd)) {
1475                         r = dm_bitset_cursor_next(&cmd->dirty_cursor);
1476                         if (r) {
1477                                 DMERR("dm_bitset_cursor_next for dirty failed");
1478                                 goto out;
1479                         }
1480                 }
1481         }
1482 out:
1483         dm_array_cursor_end(&cmd->mapping_cursor);
1484         if (hints_valid)
1485                 dm_array_cursor_end(&cmd->hint_cursor);
1486
1487         if (separate_dirty_bits(cmd))
1488                 dm_bitset_cursor_end(&cmd->dirty_cursor);
1489
1490         return r;
1491 }
1492
1493 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1494                            struct dm_cache_policy *policy,
1495                            load_mapping_fn fn, void *context)
1496 {
1497         int r;
1498
1499         READ_LOCK(cmd);
1500         r = __load_mappings(cmd, policy, fn, context);
1501         READ_UNLOCK(cmd);
1502
1503         return r;
1504 }
1505
1506 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1507 {
1508         int r = 0;
1509         __le64 value;
1510         dm_oblock_t oblock;
1511         unsigned flags;
1512
1513         memcpy(&value, leaf, sizeof(value));
1514         unpack_value(value, &oblock, &flags);
1515
1516         return r;
1517 }
1518
1519 static int __dump_mappings(struct dm_cache_metadata *cmd)
1520 {
1521         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1522 }
1523
1524 void dm_cache_dump(struct dm_cache_metadata *cmd)
1525 {
1526         READ_LOCK_VOID(cmd);
1527         __dump_mappings(cmd);
1528         READ_UNLOCK(cmd);
1529 }
1530
1531 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1532 {
1533         int r;
1534
1535         READ_LOCK(cmd);
1536         r = cmd->changed;
1537         READ_UNLOCK(cmd);
1538
1539         return r;
1540 }
1541
1542 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1543 {
1544         int r;
1545         unsigned flags;
1546         dm_oblock_t oblock;
1547         __le64 value;
1548
1549         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1550         if (r)
1551                 return r;
1552
1553         unpack_value(value, &oblock, &flags);
1554
1555         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1556                 /* nothing to be done */
1557                 return 0;
1558
1559         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1560         __dm_bless_for_disk(&value);
1561
1562         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1563                                &value, &cmd->root);
1564         if (r)
1565                 return r;
1566
1567         cmd->changed = true;
1568         return 0;
1569
1570 }
1571
1572 static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1573 {
1574         int r;
1575         unsigned i;
1576         for (i = 0; i < nr_bits; i++) {
1577                 r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
1578                 if (r)
1579                         return r;
1580         }
1581
1582         return 0;
1583 }
1584
1585 static int is_dirty_callback(uint32_t index, bool *value, void *context)
1586 {
1587         unsigned long *bits = context;
1588         *value = test_bit(index, bits);
1589         return 0;
1590 }
1591
1592 static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1593 {
1594         int r = 0;
1595
1596         /* nr_bits is really just a sanity check */
1597         if (nr_bits != from_cblock(cmd->cache_blocks)) {
1598                 DMERR("dirty bitset is wrong size");
1599                 return -EINVAL;
1600         }
1601
1602         r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root);
1603         if (r)
1604                 return r;
1605
1606         cmd->changed = true;
1607         return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits);
1608 }
1609
1610 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
1611                             unsigned nr_bits,
1612                             unsigned long *bits)
1613 {
1614         int r;
1615
1616         WRITE_LOCK(cmd);
1617         if (separate_dirty_bits(cmd))
1618                 r = __set_dirty_bits_v2(cmd, nr_bits, bits);
1619         else
1620                 r = __set_dirty_bits_v1(cmd, nr_bits, bits);
1621         WRITE_UNLOCK(cmd);
1622
1623         return r;
1624 }
1625
1626 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1627                                  struct dm_cache_statistics *stats)
1628 {
1629         READ_LOCK_VOID(cmd);
1630         *stats = cmd->stats;
1631         READ_UNLOCK(cmd);
1632 }
1633
1634 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1635                                  struct dm_cache_statistics *stats)
1636 {
1637         WRITE_LOCK_VOID(cmd);
1638         cmd->stats = *stats;
1639         WRITE_UNLOCK(cmd);
1640 }
1641
1642 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1643 {
1644         int r = -EINVAL;
1645         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1646                                  clear_clean_shutdown);
1647
1648         WRITE_LOCK(cmd);
1649         if (cmd->fail_io)
1650                 goto out;
1651
1652         r = __commit_transaction(cmd, mutator);
1653         if (r)
1654                 goto out;
1655
1656         r = __begin_transaction(cmd);
1657 out:
1658         WRITE_UNLOCK(cmd);
1659         return r;
1660 }
1661
1662 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1663                                            dm_block_t *result)
1664 {
1665         int r = -EINVAL;
1666
1667         READ_LOCK(cmd);
1668         if (!cmd->fail_io)
1669                 r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1670         READ_UNLOCK(cmd);
1671
1672         return r;
1673 }
1674
1675 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1676                                    dm_block_t *result)
1677 {
1678         int r = -EINVAL;
1679
1680         READ_LOCK(cmd);
1681         if (!cmd->fail_io)
1682                 r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1683         READ_UNLOCK(cmd);
1684
1685         return r;
1686 }
1687
1688 /*----------------------------------------------------------------*/
1689
1690 static int get_hint(uint32_t index, void *value_le, void *context)
1691 {
1692         uint32_t value;
1693         struct dm_cache_policy *policy = context;
1694
1695         value = policy_get_hint(policy, to_cblock(index));
1696         *((__le32 *) value_le) = cpu_to_le32(value);
1697
1698         return 0;
1699 }
1700
1701 /*
1702  * It's quicker to always delete the hint array, and recreate with
1703  * dm_array_new().
1704  */
1705 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1706 {
1707         int r;
1708         size_t hint_size;
1709         const char *policy_name = dm_cache_policy_get_name(policy);
1710         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1711
1712         if (!policy_name[0] ||
1713             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1714                 return -EINVAL;
1715
1716         strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1717         memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1718
1719         hint_size = dm_cache_policy_get_hint_size(policy);
1720         if (!hint_size)
1721                 return 0; /* short-circuit hints initialization */
1722         cmd->policy_hint_size = hint_size;
1723
1724         if (cmd->hint_root) {
1725                 r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1726                 if (r)
1727                         return r;
1728         }
1729
1730         return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1731                             from_cblock(cmd->cache_blocks),
1732                             get_hint, policy);
1733 }
1734
1735 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1736 {
1737         int r;
1738
1739         WRITE_LOCK(cmd);
1740         r = write_hints(cmd, policy);
1741         WRITE_UNLOCK(cmd);
1742
1743         return r;
1744 }
1745
1746 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1747 {
1748         int r;
1749
1750         READ_LOCK(cmd);
1751         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1752         READ_UNLOCK(cmd);
1753
1754         return r;
1755 }
1756
1757 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1758 {
1759         WRITE_LOCK_VOID(cmd);
1760         dm_bm_set_read_only(cmd->bm);
1761         WRITE_UNLOCK(cmd);
1762 }
1763
1764 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1765 {
1766         WRITE_LOCK_VOID(cmd);
1767         dm_bm_set_read_write(cmd->bm);
1768         WRITE_UNLOCK(cmd);
1769 }
1770
1771 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1772 {
1773         int r;
1774         struct dm_block *sblock;
1775         struct cache_disk_superblock *disk_super;
1776
1777         WRITE_LOCK(cmd);
1778         set_bit(NEEDS_CHECK, &cmd->flags);
1779
1780         r = superblock_lock(cmd, &sblock);
1781         if (r) {
1782                 DMERR("couldn't read superblock");
1783                 goto out;
1784         }
1785
1786         disk_super = dm_block_data(sblock);
1787         disk_super->flags = cpu_to_le32(cmd->flags);
1788
1789         dm_bm_unlock(sblock);
1790
1791 out:
1792         WRITE_UNLOCK(cmd);
1793         return r;
1794 }
1795
1796 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1797 {
1798         READ_LOCK(cmd);
1799         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1800         READ_UNLOCK(cmd);
1801
1802         return 0;
1803 }
1804
1805 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1806 {
1807         int r;
1808
1809         WRITE_LOCK(cmd);
1810         __destroy_persistent_data_objects(cmd);
1811         r = __create_persistent_data_objects(cmd, false);
1812         if (r)
1813                 cmd->fail_io = true;
1814         WRITE_UNLOCK(cmd);
1815
1816         return r;
1817 }