drivers/md/dm-cache-metadata.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-cache-metadata.h"
   8
   9 #include "persistent-data/dm-array.h"
  10 #include "persistent-data/dm-bitset.h"
  11 #include "persistent-data/dm-space-map.h"
  12 #include "persistent-data/dm-space-map-disk.h"
  13 #include "persistent-data/dm-transaction-manager.h"
  14
  15 #include <linux/device-mapper.h>
  16
  17 /*----------------------------------------------------------------*/
  18
  19 #define DM_MSG_PREFIX   "cache metadata"
  20
  21 #define CACHE_SUPERBLOCK_MAGIC 06142003
  22 #define CACHE_SUPERBLOCK_LOCATION 0
  23 #define CACHE_VERSION 1
  24 #define CACHE_METADATA_CACHE_SIZE 64
  25
  26 /*
  27  *  3 for btree insert +
  28  *  2 for btree lookup used within space map
  29  */
  30 #define CACHE_MAX_CONCURRENT_LOCKS 5
  31 #define SPACE_MAP_ROOT_SIZE 128
  32
  33 enum superblock_flag_bits {
  34         /* for spotting crashes that would invalidate the dirty bitset */
  35         CLEAN_SHUTDOWN,
  36 };
  37
  38 /*
  39  * Each mapping from cache block -> origin block carries a set of flags.
  40  */
  41 enum mapping_bits {
  42         /*
  43          * A valid mapping.  Because we're using an array we clear this
  44          * flag for an non existant mapping.
  45          */
  46         M_VALID = 1,
  47
  48         /*
  49          * The data on the cache is different from that on the origin.
  50          */
  51         M_DIRTY = 2
  52 };
  53
  54 struct cache_disk_superblock {
  55         __le32 csum;
  56         __le32 flags;
  57         __le64 blocknr;
  58
  59         __u8 uuid[16];
  60         __le64 magic;
  61         __le32 version;
  62
  63         __u8 policy_name[CACHE_POLICY_NAME_SIZE];
  64         __le32 policy_hint_size;
  65
  66         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
  67         __le64 mapping_root;
  68         __le64 hint_root;
  69
  70         __le64 discard_root;
  71         __le64 discard_block_size;
  72         __le64 discard_nr_blocks;
  73
  74         __le32 data_block_size;
  75         __le32 metadata_block_size;
  76         __le32 cache_blocks;
  77
  78         __le32 compat_flags;
  79         __le32 compat_ro_flags;
  80         __le32 incompat_flags;
  81
  82         __le32 read_hits;
  83         __le32 read_misses;
  84         __le32 write_hits;
  85         __le32 write_misses;
  86
  87         __le32 policy_version[CACHE_POLICY_VERSION_SIZE];
  88 } __packed;
  89
  90 struct dm_cache_metadata {
  91         struct block_device *bdev;
  92         struct dm_block_manager *bm;
  93         struct dm_space_map *metadata_sm;
  94         struct dm_transaction_manager *tm;
  95
  96         struct dm_array_info info;
  97         struct dm_array_info hint_info;
  98         struct dm_disk_bitset discard_info;
  99
 100         struct rw_semaphore root_lock;
 101         dm_block_t root;
 102         dm_block_t hint_root;
 103         dm_block_t discard_root;
 104
 105         sector_t discard_block_size;
 106         dm_dblock_t discard_nr_blocks;
 107
 108         sector_t data_block_size;
 109         dm_cblock_t cache_blocks;
 110         bool changed:1;
 111         bool clean_when_opened:1;
 112
 113         char policy_name[CACHE_POLICY_NAME_SIZE];
 114         unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
 115         size_t policy_hint_size;
 116         struct dm_cache_statistics stats;
 117 };
 118
 119 /*-------------------------------------------------------------------
 120  * superblock validator
 121  *-----------------------------------------------------------------*/
 122
 123 #define SUPERBLOCK_CSUM_XOR 9031977
 124
 125 static void sb_prepare_for_write(struct dm_block_validator *v,
 126                                  struct dm_block *b,
 127                                  size_t sb_block_size)
 128 {
 129         struct cache_disk_superblock *disk_super = dm_block_data(b);
 130
 131         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 132         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 133                                                       sb_block_size - sizeof(__le32),
 134                                                       SUPERBLOCK_CSUM_XOR));
 135 }
 136
 137 static int sb_check(struct dm_block_validator *v,
 138                     struct dm_block *b,
 139                     size_t sb_block_size)
 140 {
 141         struct cache_disk_superblock *disk_super = dm_block_data(b);
 142         __le32 csum_le;
 143
 144         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 145                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 146                       le64_to_cpu(disk_super->blocknr),
 147                       (unsigned long long)dm_block_location(b));
 148                 return -ENOTBLK;
 149         }
 150
 151         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
 152                 DMERR("sb_check failed: magic %llu: wanted %llu",
 153                       le64_to_cpu(disk_super->magic),
 154                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
 155                 return -EILSEQ;
 156         }
 157
 158         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 159                                              sb_block_size - sizeof(__le32),
 160                                              SUPERBLOCK_CSUM_XOR));
 161         if (csum_le != disk_super->csum) {
 162                 DMERR("sb_check failed: csum %u: wanted %u",
 163                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 164                 return -EILSEQ;
 165         }
 166
 167         return 0;
 168 }
 169
 170 static struct dm_block_validator sb_validator = {
 171         .name = "superblock",
 172         .prepare_for_write = sb_prepare_for_write,
 173         .check = sb_check
 174 };
 175
 176 /*----------------------------------------------------------------*/
 177
 178 static int superblock_read_lock(struct dm_cache_metadata *cmd,
 179                                 struct dm_block **sblock)
 180 {
 181         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 182                                &sb_validator, sblock);
 183 }
 184
 185 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
 186                                 struct dm_block **sblock)
 187 {
 188         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 189                                      &sb_validator, sblock);
 190 }
 191
 192 static int superblock_lock(struct dm_cache_metadata *cmd,
 193                            struct dm_block **sblock)
 194 {
 195         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 196                                 &sb_validator, sblock);
 197 }
 198
 199 /*----------------------------------------------------------------*/
 200
 201 static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
 202 {
 203         int r;
 204         unsigned i;
 205         struct dm_block *b;
 206         __le64 *data_le, zero = cpu_to_le64(0);
 207         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 208
 209         /*
 210          * We can't use a validator here - it may be all zeroes.
 211          */
 212         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
 213         if (r)
 214                 return r;
 215
 216         data_le = dm_block_data(b);
 217         *result = 1;
 218         for (i = 0; i < sb_block_size; i++) {
 219                 if (data_le[i] != zero) {
 220                         *result = 0;
 221                         break;
 222                 }
 223         }
 224
 225         return dm_bm_unlock(b);
 226 }
 227
 228 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 229 {
 230         struct dm_btree_value_type vt;
 231
 232         vt.context = NULL;
 233         vt.size = sizeof(__le64);
 234         vt.inc = NULL;
 235         vt.dec = NULL;
 236         vt.equal = NULL;
 237         dm_array_info_init(&cmd->info, cmd->tm, &vt);
 238
 239         if (cmd->policy_hint_size) {
 240                 vt.size = sizeof(__le32);
 241                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
 242         }
 243 }
 244
 245 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 246 {
 247         int r;
 248         struct dm_block *sblock;
 249         size_t metadata_len;
 250         struct cache_disk_superblock *disk_super;
 251         sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
 252
 253         /* FIXME: see if we can lose the max sectors limit */
 254         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 255                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 256
 257         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 258         if (r < 0)
 259                 return r;
 260
 261         r = dm_tm_pre_commit(cmd->tm);
 262         if (r < 0)
 263                 return r;
 264
 265         r = superblock_lock_zero(cmd, &sblock);
 266         if (r)
 267                 return r;
 268
 269         disk_super = dm_block_data(sblock);
 270         disk_super->flags = 0;
 271         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 272         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
 273         disk_super->version = cpu_to_le32(CACHE_VERSION);
 274         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 275         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
 276         disk_super->policy_hint_size = 0;
 277
 278         r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root,
 279                             metadata_len);
 280         if (r < 0)
 281                 goto bad_locked;
 282
 283         disk_super->mapping_root = cpu_to_le64(cmd->root);
 284         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 285         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 286         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 287         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 288         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 289         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 290         disk_super->cache_blocks = cpu_to_le32(0);
 291
 292         disk_super->read_hits = cpu_to_le32(0);
 293         disk_super->read_misses = cpu_to_le32(0);
 294         disk_super->write_hits = cpu_to_le32(0);
 295         disk_super->write_misses = cpu_to_le32(0);
 296
 297         return dm_tm_commit(cmd->tm, sblock);
 298
 299 bad_locked:
 300         dm_bm_unlock(sblock);
 301         return r;
 302 }
 303
 304 static int __format_metadata(struct dm_cache_metadata *cmd)
 305 {
 306         int r;
 307
 308         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 309                                  &cmd->tm, &cmd->metadata_sm);
 310         if (r < 0) {
 311                 DMERR("tm_create_with_sm failed");
 312                 return r;
 313         }
 314
 315         __setup_mapping_info(cmd);
 316
 317         r = dm_array_empty(&cmd->info, &cmd->root);
 318         if (r < 0)
 319                 goto bad;
 320
 321         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 322
 323         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
 324         if (r < 0)
 325                 goto bad;
 326
 327         cmd->discard_block_size = 0;
 328         cmd->discard_nr_blocks = 0;
 329
 330         r = __write_initial_superblock(cmd);
 331         if (r)
 332                 goto bad;
 333
 334         cmd->clean_when_opened = true;
 335         return 0;
 336
 337 bad:
 338         dm_tm_destroy(cmd->tm);
 339         dm_sm_destroy(cmd->metadata_sm);
 340
 341         return r;
 342 }
 343
 344 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
 345                                      struct dm_cache_metadata *cmd)
 346 {
 347         uint32_t features;
 348
 349         features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
 350         if (features) {
 351                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 352                       (unsigned long)features);
 353                 return -EINVAL;
 354         }
 355
 356         /*
 357          * Check for read-only metadata to skip the following RDWR checks.
 358          */
 359         if (get_disk_ro(cmd->bdev->bd_disk))
 360                 return 0;
 361
 362         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
 363         if (features) {
 364                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 365                       (unsigned long)features);
 366                 return -EINVAL;
 367         }
 368
 369         return 0;
 370 }
 371
 372 static int __open_metadata(struct dm_cache_metadata *cmd)
 373 {
 374         int r;
 375         struct dm_block *sblock;
 376         struct cache_disk_superblock *disk_super;
 377         unsigned long sb_flags;
 378
 379         r = superblock_read_lock(cmd, &sblock);
 380         if (r < 0) {
 381                 DMERR("couldn't read lock superblock");
 382                 return r;
 383         }
 384
 385         disk_super = dm_block_data(sblock);
 386
 387         r = __check_incompat_features(disk_super, cmd);
 388         if (r < 0)
 389                 goto bad;
 390
 391         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 392                                disk_super->metadata_space_map_root,
 393                                sizeof(disk_super->metadata_space_map_root),
 394                                &cmd->tm, &cmd->metadata_sm);
 395         if (r < 0) {
 396                 DMERR("tm_open_with_sm failed");
 397                 goto bad;
 398         }
 399
 400         __setup_mapping_info(cmd);
 401         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 402         sb_flags = le32_to_cpu(disk_super->flags);
 403         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 404         return dm_bm_unlock(sblock);
 405
 406 bad:
 407         dm_bm_unlock(sblock);
 408         return r;
 409 }
 410
 411 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 412                                      bool format_device)
 413 {
 414         int r, unformatted;
 415
 416         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 417         if (r)
 418                 return r;
 419
 420         if (unformatted)
 421                 return format_device ? __format_metadata(cmd) : -EPERM;
 422
 423         return __open_metadata(cmd);
 424 }
 425
 426 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 427                                             bool may_format_device)
 428 {
 429         int r;
 430         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE,
 431                                           CACHE_METADATA_CACHE_SIZE,
 432                                           CACHE_MAX_CONCURRENT_LOCKS);
 433         if (IS_ERR(cmd->bm)) {
 434                 DMERR("could not create block manager");
 435                 return PTR_ERR(cmd->bm);
 436         }
 437
 438         r = __open_or_format_metadata(cmd, may_format_device);
 439         if (r)
 440                 dm_block_manager_destroy(cmd->bm);
 441
 442         return r;
 443 }
 444
 445 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
 446 {
 447         dm_sm_destroy(cmd->metadata_sm);
 448         dm_tm_destroy(cmd->tm);
 449         dm_block_manager_destroy(cmd->bm);
 450 }
 451
 452 typedef unsigned long (*flags_mutator)(unsigned long);
 453
 454 static void update_flags(struct cache_disk_superblock *disk_super,
 455                          flags_mutator mutator)
 456 {
 457         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 458         disk_super->flags = cpu_to_le32(sb_flags);
 459 }
 460
 461 static unsigned long set_clean_shutdown(unsigned long flags)
 462 {
 463         set_bit(CLEAN_SHUTDOWN, &flags);
 464         return flags;
 465 }
 466
 467 static unsigned long clear_clean_shutdown(unsigned long flags)
 468 {
 469         clear_bit(CLEAN_SHUTDOWN, &flags);
 470         return flags;
 471 }
 472
 473 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 474                                    struct cache_disk_superblock *disk_super)
 475 {
 476         cmd->root = le64_to_cpu(disk_super->mapping_root);
 477         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 478         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 479         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 480         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
 481         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 482         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 483         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 484         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 485         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 486         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 487         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 488
 489         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 490         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 491         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 492         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 493
 494         cmd->changed = false;
 495 }
 496
 497 /*
 498  * The mutator updates the superblock flags.
 499  */
 500 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 501                                      flags_mutator mutator)
 502 {
 503         int r;
 504         struct cache_disk_superblock *disk_super;
 505         struct dm_block *sblock;
 506
 507         r = superblock_lock(cmd, &sblock);
 508         if (r)
 509                 return r;
 510
 511         disk_super = dm_block_data(sblock);
 512         update_flags(disk_super, mutator);
 513         read_superblock_fields(cmd, disk_super);
 514
 515         return dm_bm_flush_and_unlock(cmd->bm, sblock);
 516 }
 517
 518 static int __begin_transaction(struct dm_cache_metadata *cmd)
 519 {
 520         int r;
 521         struct cache_disk_superblock *disk_super;
 522         struct dm_block *sblock;
 523
 524         /*
 525          * We re-read the superblock every time.  Shouldn't need to do this
 526          * really.
 527          */
 528         r = superblock_read_lock(cmd, &sblock);
 529         if (r)
 530                 return r;
 531
 532         disk_super = dm_block_data(sblock);
 533         read_superblock_fields(cmd, disk_super);
 534         dm_bm_unlock(sblock);
 535
 536         return 0;
 537 }
 538
 539 static int __commit_transaction(struct dm_cache_metadata *cmd,
 540                                 flags_mutator mutator)
 541 {
 542         int r;
 543         size_t metadata_len;
 544         struct cache_disk_superblock *disk_super;
 545         struct dm_block *sblock;
 546
 547         /*
 548          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 549          */
 550         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 551
 552         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 553                             &cmd->discard_root);
 554         if (r)
 555                 return r;
 556
 557         r = dm_tm_pre_commit(cmd->tm);
 558         if (r < 0)
 559                 return r;
 560
 561         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 562         if (r < 0)
 563                 return r;
 564
 565         r = superblock_lock(cmd, &sblock);
 566         if (r)
 567                 return r;
 568
 569         disk_super = dm_block_data(sblock);
 570
 571         if (mutator)
 572                 update_flags(disk_super, mutator);
 573
 574         disk_super->mapping_root = cpu_to_le64(cmd->root);
 575         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 576         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 577         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 578         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 579         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 580         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 581         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 582         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 583         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 584
 585         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 586         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 587         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 588         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 589
 590         r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root,
 591                             metadata_len);
 592         if (r < 0) {
 593                 dm_bm_unlock(sblock);
 594                 return r;
 595         }
 596
 597         return dm_tm_commit(cmd->tm, sblock);
 598 }
 599
 600 /*----------------------------------------------------------------*/
 601
 602 /*
 603  * The mappings are held in a dm-array that has 64-bit values stored in
 604  * little-endian format.  The index is the cblock, the high 48bits of the
 605  * value are the oblock and the low 16 bit the flags.
 606  */
 607 #define FLAGS_MASK ((1 << 16) - 1)
 608
 609 static __le64 pack_value(dm_oblock_t block, unsigned flags)
 610 {
 611         uint64_t value = from_oblock(block);
 612         value <<= 16;
 613         value = value | (flags & FLAGS_MASK);
 614         return cpu_to_le64(value);
 615 }
 616
 617 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 618 {
 619         uint64_t value = le64_to_cpu(value_le);
 620         uint64_t b = value >> 16;
 621         *block = to_oblock(b);
 622         *flags = value & FLAGS_MASK;
 623 }
 624
 625 /*----------------------------------------------------------------*/
 626
 627 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 628                                                  sector_t data_block_size,
 629                                                  bool may_format_device,
 630                                                  size_t policy_hint_size)
 631 {
 632         int r;
 633         struct dm_cache_metadata *cmd;
 634
 635         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 636         if (!cmd) {
 637                 DMERR("could not allocate metadata struct");
 638                 return NULL;
 639         }
 640
 641         init_rwsem(&cmd->root_lock);
 642         cmd->bdev = bdev;
 643         cmd->data_block_size = data_block_size;
 644         cmd->cache_blocks = 0;
 645         cmd->policy_hint_size = policy_hint_size;
 646         cmd->changed = true;
 647
 648         r = __create_persistent_data_objects(cmd, may_format_device);
 649         if (r) {
 650                 kfree(cmd);
 651                 return ERR_PTR(r);
 652         }
 653
 654         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 655         if (r < 0) {
 656                 dm_cache_metadata_close(cmd);
 657                 return ERR_PTR(r);
 658         }
 659
 660         return cmd;
 661 }
 662
 663 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 664 {
 665         __destroy_persistent_data_objects(cmd);
 666         kfree(cmd);
 667 }
 668
 669 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 670 {
 671         int r;
 672         __le64 null_mapping = pack_value(0, 0);
 673
 674         down_write(&cmd->root_lock);
 675         __dm_bless_for_disk(&null_mapping);
 676         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
 677                             from_cblock(new_cache_size),
 678                             &null_mapping, &cmd->root);
 679         if (!r)
 680                 cmd->cache_blocks = new_cache_size;
 681         cmd->changed = true;
 682         up_write(&cmd->root_lock);
 683
 684         return r;
 685 }
 686
 687 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 688                                    sector_t discard_block_size,
 689                                    dm_dblock_t new_nr_entries)
 690 {
 691         int r;
 692
 693         down_write(&cmd->root_lock);
 694         r = dm_bitset_resize(&cmd->discard_info,
 695                              cmd->discard_root,
 696                              from_dblock(cmd->discard_nr_blocks),
 697                              from_dblock(new_nr_entries),
 698                              false, &cmd->discard_root);
 699         if (!r) {
 700                 cmd->discard_block_size = discard_block_size;
 701                 cmd->discard_nr_blocks = new_nr_entries;
 702         }
 703
 704         cmd->changed = true;
 705         up_write(&cmd->root_lock);
 706
 707         return r;
 708 }
 709
 710 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
 711 {
 712         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
 713                                  from_dblock(b), &cmd->discard_root);
 714 }
 715
 716 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
 717 {
 718         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
 719                                    from_dblock(b), &cmd->discard_root);
 720 }
 721
 722 static int __is_discarded(struct dm_cache_metadata *cmd, dm_dblock_t b,
 723                           bool *is_discarded)
 724 {
 725         return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
 726                                   from_dblock(b), &cmd->discard_root,
 727                                   is_discarded);
 728 }
 729
 730 static int __discard(struct dm_cache_metadata *cmd,
 731                      dm_dblock_t dblock, bool discard)
 732 {
 733         int r;
 734
 735         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
 736         if (r)
 737                 return r;
 738
 739         cmd->changed = true;
 740         return 0;
 741 }
 742
 743 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
 744                          dm_dblock_t dblock, bool discard)
 745 {
 746         int r;
 747
 748         down_write(&cmd->root_lock);
 749         r = __discard(cmd, dblock, discard);
 750         up_write(&cmd->root_lock);
 751
 752         return r;
 753 }
 754
 755 static int __load_discards(struct dm_cache_metadata *cmd,
 756                            load_discard_fn fn, void *context)
 757 {
 758         int r = 0;
 759         dm_block_t b;
 760         bool discard;
 761
 762         for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
 763                 dm_dblock_t dblock = to_dblock(b);
 764
 765                 if (cmd->clean_when_opened) {
 766                         r = __is_discarded(cmd, dblock, &discard);
 767                         if (r)
 768                                 return r;
 769                 } else
 770                         discard = false;
 771
 772                 r = fn(context, cmd->discard_block_size, dblock, discard);
 773                 if (r)
 774                         break;
 775         }
 776
 777         return r;
 778 }
 779
 780 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
 781                            load_discard_fn fn, void *context)
 782 {
 783         int r;
 784
 785         down_read(&cmd->root_lock);
 786         r = __load_discards(cmd, fn, context);
 787         up_read(&cmd->root_lock);
 788
 789         return r;
 790 }
 791
 792 dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd)
 793 {
 794         dm_cblock_t r;
 795
 796         down_read(&cmd->root_lock);
 797         r = cmd->cache_blocks;
 798         up_read(&cmd->root_lock);
 799
 800         return r;
 801 }
 802
 803 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
 804 {
 805         int r;
 806         __le64 value = pack_value(0, 0);
 807
 808         __dm_bless_for_disk(&value);
 809         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
 810                                &value, &cmd->root);
 811         if (r)
 812                 return r;
 813
 814         cmd->changed = true;
 815         return 0;
 816 }
 817
 818 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
 819 {
 820         int r;
 821
 822         down_write(&cmd->root_lock);
 823         r = __remove(cmd, cblock);
 824         up_write(&cmd->root_lock);
 825
 826         return r;
 827 }
 828
 829 static int __insert(struct dm_cache_metadata *cmd,
 830                     dm_cblock_t cblock, dm_oblock_t oblock)
 831 {
 832         int r;
 833         __le64 value = pack_value(oblock, M_VALID);
 834         __dm_bless_for_disk(&value);
 835
 836         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
 837                                &value, &cmd->root);
 838         if (r)
 839                 return r;
 840
 841         cmd->changed = true;
 842         return 0;
 843 }
 844
 845 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
 846                             dm_cblock_t cblock, dm_oblock_t oblock)
 847 {
 848         int r;
 849
 850         down_write(&cmd->root_lock);
 851         r = __insert(cmd, cblock, oblock);
 852         up_write(&cmd->root_lock);
 853
 854         return r;
 855 }
 856
 857 struct thunk {
 858         load_mapping_fn fn;
 859         void *context;
 860
 861         struct dm_cache_metadata *cmd;
 862         bool respect_dirty_flags;
 863         bool hints_valid;
 864 };
 865
 866 static bool policy_unchanged(struct dm_cache_metadata *cmd,
 867                              struct dm_cache_policy *policy)
 868 {
 869         const char *policy_name = dm_cache_policy_get_name(policy);
 870         const unsigned *policy_version = dm_cache_policy_get_version(policy);
 871         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
 872
 873         /*
 874          * Ensure policy names match.
 875          */
 876         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
 877                 return false;
 878
 879         /*
 880          * Ensure policy major versions match.
 881          */
 882         if (cmd->policy_version[0] != policy_version[0])
 883                 return false;
 884
 885         /*
 886          * Ensure policy hint sizes match.
 887          */
 888         if (cmd->policy_hint_size != policy_hint_size)
 889                 return false;
 890
 891         return true;
 892 }
 893
 894 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
 895 {
 896         return cmd->hint_root && cmd->policy_hint_size;
 897 }
 898
 899 static bool hints_array_available(struct dm_cache_metadata *cmd,
 900                                   struct dm_cache_policy *policy)
 901 {
 902         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
 903                 hints_array_initialized(cmd);
 904 }
 905
 906 static int __load_mapping(void *context, uint64_t cblock, void *leaf)
 907 {
 908         int r = 0;
 909         bool dirty;
 910         __le64 value;
 911         __le32 hint_value = 0;
 912         dm_oblock_t oblock;
 913         unsigned flags;
 914         struct thunk *thunk = context;
 915         struct dm_cache_metadata *cmd = thunk->cmd;
 916
 917         memcpy(&value, leaf, sizeof(value));
 918         unpack_value(value, &oblock, &flags);
 919
 920         if (flags & M_VALID) {
 921                 if (thunk->hints_valid) {
 922                         r = dm_array_get_value(&cmd->hint_info, cmd->hint_root,
 923                                                cblock, &hint_value);
 924                         if (r && r != -ENODATA)
 925                                 return r;
 926                 }
 927
 928                 dirty = thunk->respect_dirty_flags ? (flags & M_DIRTY) : true;
 929                 r = thunk->fn(thunk->context, oblock, to_cblock(cblock),
 930                               dirty, le32_to_cpu(hint_value), thunk->hints_valid);
 931         }
 932
 933         return r;
 934 }
 935
 936 static int __load_mappings(struct dm_cache_metadata *cmd,
 937                            struct dm_cache_policy *policy,
 938                            load_mapping_fn fn, void *context)
 939 {
 940         struct thunk thunk;
 941
 942         thunk.fn = fn;
 943         thunk.context = context;
 944
 945         thunk.cmd = cmd;
 946         thunk.respect_dirty_flags = cmd->clean_when_opened;
 947         thunk.hints_valid = hints_array_available(cmd, policy);
 948
 949         return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
 950 }
 951
 952 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
 953                            struct dm_cache_policy *policy,
 954                            load_mapping_fn fn, void *context)
 955 {
 956         int r;
 957
 958         down_read(&cmd->root_lock);
 959         r = __load_mappings(cmd, policy, fn, context);
 960         up_read(&cmd->root_lock);
 961
 962         return r;
 963 }
 964
 965 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
 966 {
 967         int r = 0;
 968         __le64 value;
 969         dm_oblock_t oblock;
 970         unsigned flags;
 971
 972         memcpy(&value, leaf, sizeof(value));
 973         unpack_value(value, &oblock, &flags);
 974
 975         return r;
 976 }
 977
 978 static int __dump_mappings(struct dm_cache_metadata *cmd)
 979 {
 980         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
 981 }
 982
 983 void dm_cache_dump(struct dm_cache_metadata *cmd)
 984 {
 985         down_read(&cmd->root_lock);
 986         __dump_mappings(cmd);
 987         up_read(&cmd->root_lock);
 988 }
 989
 990 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
 991 {
 992         int r;
 993
 994         down_read(&cmd->root_lock);
 995         r = cmd->changed;
 996         up_read(&cmd->root_lock);
 997
 998         return r;
 999 }
1000
1001 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1002 {
1003         int r;
1004         unsigned flags;
1005         dm_oblock_t oblock;
1006         __le64 value;
1007
1008         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1009         if (r)
1010                 return r;
1011
1012         unpack_value(value, &oblock, &flags);
1013
1014         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1015                 /* nothing to be done */
1016                 return 0;
1017
1018         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1019         __dm_bless_for_disk(&value);
1020
1021         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1022                                &value, &cmd->root);
1023         if (r)
1024                 return r;
1025
1026         cmd->changed = true;
1027         return 0;
1028
1029 }
1030
1031 int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
1032                        dm_cblock_t cblock, bool dirty)
1033 {
1034         int r;
1035
1036         down_write(&cmd->root_lock);
1037         r = __dirty(cmd, cblock, dirty);
1038         up_write(&cmd->root_lock);
1039
1040         return r;
1041 }
1042
1043 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1044                                  struct dm_cache_statistics *stats)
1045 {
1046         down_read(&cmd->root_lock);
1047         memcpy(stats, &cmd->stats, sizeof(*stats));
1048         up_read(&cmd->root_lock);
1049 }
1050
1051 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1052                                  struct dm_cache_statistics *stats)
1053 {
1054         down_write(&cmd->root_lock);
1055         memcpy(&cmd->stats, stats, sizeof(*stats));
1056         up_write(&cmd->root_lock);
1057 }
1058
1059 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1060 {
1061         int r;
1062         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1063                                  clear_clean_shutdown);
1064
1065         down_write(&cmd->root_lock);
1066         r = __commit_transaction(cmd, mutator);
1067         if (r)
1068                 goto out;
1069
1070         r = __begin_transaction(cmd);
1071
1072 out:
1073         up_write(&cmd->root_lock);
1074         return r;
1075 }
1076
1077 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1078                                            dm_block_t *result)
1079 {
1080         int r = -EINVAL;
1081
1082         down_read(&cmd->root_lock);
1083         r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1084         up_read(&cmd->root_lock);
1085
1086         return r;
1087 }
1088
1089 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1090                                    dm_block_t *result)
1091 {
1092         int r = -EINVAL;
1093
1094         down_read(&cmd->root_lock);
1095         r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1096         up_read(&cmd->root_lock);
1097
1098         return r;
1099 }
1100
1101 /*----------------------------------------------------------------*/
1102
1103 static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1104 {
1105         int r;
1106         __le32 value;
1107         size_t hint_size;
1108         const char *policy_name = dm_cache_policy_get_name(policy);
1109         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1110
1111         if (!policy_name[0] ||
1112             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1113                 return -EINVAL;
1114
1115         if (!policy_unchanged(cmd, policy)) {
1116                 strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1117                 memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1118
1119                 hint_size = dm_cache_policy_get_hint_size(policy);
1120                 if (!hint_size)
1121                         return 0; /* short-circuit hints initialization */
1122                 cmd->policy_hint_size = hint_size;
1123
1124                 if (cmd->hint_root) {
1125                         r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1126                         if (r)
1127                                 return r;
1128                 }
1129
1130                 r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
1131                 if (r)
1132                         return r;
1133
1134                 value = cpu_to_le32(0);
1135                 __dm_bless_for_disk(&value);
1136                 r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
1137                                     from_cblock(cmd->cache_blocks),
1138                                     &value, &cmd->hint_root);
1139                 if (r)
1140                         return r;
1141         }
1142
1143         return 0;
1144 }
1145
1146 int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1147 {
1148         int r;
1149
1150         down_write(&cmd->root_lock);
1151         r = begin_hints(cmd, policy);
1152         up_write(&cmd->root_lock);
1153
1154         return r;
1155 }
1156
1157 static int save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
1158                      uint32_t hint)
1159 {
1160         int r;
1161         __le32 value = cpu_to_le32(hint);
1162         __dm_bless_for_disk(&value);
1163
1164         r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
1165                                from_cblock(cblock), &value, &cmd->hint_root);
1166         cmd->changed = true;
1167
1168         return r;
1169 }
1170
1171 int dm_cache_save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
1172                        uint32_t hint)
1173 {
1174         int r;
1175
1176         if (!hints_array_initialized(cmd))
1177                 return 0;
1178
1179         down_write(&cmd->root_lock);
1180         r = save_hint(cmd, cblock, hint);
1181         up_write(&cmd->root_lock);
1182
1183         return r;
1184 }