drivers/md/dm-cache-metadata.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-cache-metadata.h"
   8
   9 #include "persistent-data/dm-array.h"
  10 #include "persistent-data/dm-bitset.h"
  11 #include "persistent-data/dm-space-map.h"
  12 #include "persistent-data/dm-space-map-disk.h"
  13 #include "persistent-data/dm-transaction-manager.h"
  14
  15 #include <linux/device-mapper.h>
  16
  17 /*----------------------------------------------------------------*/
  18
  19 #define DM_MSG_PREFIX   "cache metadata"
  20
  21 #define CACHE_SUPERBLOCK_MAGIC 06142003
  22 #define CACHE_SUPERBLOCK_LOCATION 0
  23
  24 /*
  25  * defines a range of metadata versions that this module can handle.
  26  */
  27 #define MIN_CACHE_VERSION 1
  28 #define MAX_CACHE_VERSION 1
  29
  30 #define CACHE_METADATA_CACHE_SIZE 64
  31
  32 /*
  33  *  3 for btree insert +
  34  *  2 for btree lookup used within space map
  35  */
  36 #define CACHE_MAX_CONCURRENT_LOCKS 5
  37 #define SPACE_MAP_ROOT_SIZE 128
  38
  39 enum superblock_flag_bits {
  40         /* for spotting crashes that would invalidate the dirty bitset */
  41         CLEAN_SHUTDOWN,
  42 };
  43
  44 /*
  45  * Each mapping from cache block -> origin block carries a set of flags.
  46  */
  47 enum mapping_bits {
  48         /*
  49          * A valid mapping.  Because we're using an array we clear this
  50          * flag for an non existant mapping.
  51          */
  52         M_VALID = 1,
  53
  54         /*
  55          * The data on the cache is different from that on the origin.
  56          */
  57         M_DIRTY = 2
  58 };
  59
  60 struct cache_disk_superblock {
  61         __le32 csum;
  62         __le32 flags;
  63         __le64 blocknr;
  64
  65         __u8 uuid[16];
  66         __le64 magic;
  67         __le32 version;
  68
  69         __u8 policy_name[CACHE_POLICY_NAME_SIZE];
  70         __le32 policy_hint_size;
  71
  72         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
  73         __le64 mapping_root;
  74         __le64 hint_root;
  75
  76         __le64 discard_root;
  77         __le64 discard_block_size;
  78         __le64 discard_nr_blocks;
  79
  80         __le32 data_block_size;
  81         __le32 metadata_block_size;
  82         __le32 cache_blocks;
  83
  84         __le32 compat_flags;
  85         __le32 compat_ro_flags;
  86         __le32 incompat_flags;
  87
  88         __le32 read_hits;
  89         __le32 read_misses;
  90         __le32 write_hits;
  91         __le32 write_misses;
  92
  93         __le32 policy_version[CACHE_POLICY_VERSION_SIZE];
  94 } __packed;
  95
  96 struct dm_cache_metadata {
  97         struct block_device *bdev;
  98         struct dm_block_manager *bm;
  99         struct dm_space_map *metadata_sm;
 100         struct dm_transaction_manager *tm;
 101
 102         struct dm_array_info info;
 103         struct dm_array_info hint_info;
 104         struct dm_disk_bitset discard_info;
 105
 106         struct rw_semaphore root_lock;
 107         dm_block_t root;
 108         dm_block_t hint_root;
 109         dm_block_t discard_root;
 110
 111         sector_t discard_block_size;
 112         dm_oblock_t discard_nr_blocks;
 113
 114         sector_t data_block_size;
 115         dm_cblock_t cache_blocks;
 116         bool changed:1;
 117         bool clean_when_opened:1;
 118
 119         char policy_name[CACHE_POLICY_NAME_SIZE];
 120         unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
 121         size_t policy_hint_size;
 122         struct dm_cache_statistics stats;
 123
 124         /*
 125          * Reading the space map root can fail, so we read it into this
 126          * buffer before the superblock is locked and updated.
 127          */
 128         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 129 };
 130
 131 /*-------------------------------------------------------------------
 132  * superblock validator
 133  *-----------------------------------------------------------------*/
 134
 135 #define SUPERBLOCK_CSUM_XOR 9031977
 136
 137 static void sb_prepare_for_write(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
 143         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 144         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 145                                                       sb_block_size - sizeof(__le32),
 146                                                       SUPERBLOCK_CSUM_XOR));
 147 }
 148
 149 static int check_metadata_version(struct cache_disk_superblock *disk_super)
 150 {
 151         uint32_t metadata_version = le32_to_cpu(disk_super->version);
 152         if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
 153                 DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
 154                       metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
 155                 return -EINVAL;
 156         }
 157
 158         return 0;
 159 }
 160
 161 static int sb_check(struct dm_block_validator *v,
 162                     struct dm_block *b,
 163                     size_t sb_block_size)
 164 {
 165         struct cache_disk_superblock *disk_super = dm_block_data(b);
 166         __le32 csum_le;
 167
 168         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 169                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 170                       le64_to_cpu(disk_super->blocknr),
 171                       (unsigned long long)dm_block_location(b));
 172                 return -ENOTBLK;
 173         }
 174
 175         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
 176                 DMERR("sb_check failed: magic %llu: wanted %llu",
 177                       le64_to_cpu(disk_super->magic),
 178                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
 179                 return -EILSEQ;
 180         }
 181
 182         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 183                                              sb_block_size - sizeof(__le32),
 184                                              SUPERBLOCK_CSUM_XOR));
 185         if (csum_le != disk_super->csum) {
 186                 DMERR("sb_check failed: csum %u: wanted %u",
 187                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 188                 return -EILSEQ;
 189         }
 190
 191         return check_metadata_version(disk_super);
 192 }
 193
 194 static struct dm_block_validator sb_validator = {
 195         .name = "superblock",
 196         .prepare_for_write = sb_prepare_for_write,
 197         .check = sb_check
 198 };
 199
 200 /*----------------------------------------------------------------*/
 201
 202 static int superblock_read_lock(struct dm_cache_metadata *cmd,
 203                                 struct dm_block **sblock)
 204 {
 205         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 206                                &sb_validator, sblock);
 207 }
 208
 209 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
 210                                 struct dm_block **sblock)
 211 {
 212         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 213                                      &sb_validator, sblock);
 214 }
 215
 216 static int superblock_lock(struct dm_cache_metadata *cmd,
 217                            struct dm_block **sblock)
 218 {
 219         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 220                                 &sb_validator, sblock);
 221 }
 222
 223 /*----------------------------------------------------------------*/
 224
 225 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 226 {
 227         int r;
 228         unsigned i;
 229         struct dm_block *b;
 230         __le64 *data_le, zero = cpu_to_le64(0);
 231         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 232
 233         /*
 234          * We can't use a validator here - it may be all zeroes.
 235          */
 236         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
 237         if (r)
 238                 return r;
 239
 240         data_le = dm_block_data(b);
 241         *result = true;
 242         for (i = 0; i < sb_block_size; i++) {
 243                 if (data_le[i] != zero) {
 244                         *result = false;
 245                         break;
 246                 }
 247         }
 248
 249         return dm_bm_unlock(b);
 250 }
 251
 252 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 253 {
 254         struct dm_btree_value_type vt;
 255
 256         vt.context = NULL;
 257         vt.size = sizeof(__le64);
 258         vt.inc = NULL;
 259         vt.dec = NULL;
 260         vt.equal = NULL;
 261         dm_array_info_init(&cmd->info, cmd->tm, &vt);
 262
 263         if (cmd->policy_hint_size) {
 264                 vt.size = sizeof(__le32);
 265                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
 266         }
 267 }
 268
 269 static int __save_sm_root(struct dm_cache_metadata *cmd)
 270 {
 271         int r;
 272         size_t metadata_len;
 273
 274         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 275         if (r < 0)
 276                 return r;
 277
 278         return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
 279                                metadata_len);
 280 }
 281
 282 static void __copy_sm_root(struct dm_cache_metadata *cmd,
 283                            struct cache_disk_superblock *disk_super)
 284 {
 285         memcpy(&disk_super->metadata_space_map_root,
 286                &cmd->metadata_space_map_root,
 287                sizeof(cmd->metadata_space_map_root));
 288 }
 289
 290 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 291 {
 292         int r;
 293         struct dm_block *sblock;
 294         struct cache_disk_superblock *disk_super;
 295         sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
 296
 297         /* FIXME: see if we can lose the max sectors limit */
 298         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 299                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 300
 301         r = dm_tm_pre_commit(cmd->tm);
 302         if (r < 0)
 303                 return r;
 304
 305         /*
 306          * dm_sm_copy_root() can fail.  So we need to do it before we start
 307          * updating the superblock.
 308          */
 309         r = __save_sm_root(cmd);
 310         if (r)
 311                 return r;
 312
 313         r = superblock_lock_zero(cmd, &sblock);
 314         if (r)
 315                 return r;
 316
 317         disk_super = dm_block_data(sblock);
 318         disk_super->flags = 0;
 319         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 320         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
 321         disk_super->version = cpu_to_le32(MAX_CACHE_VERSION);
 322         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 323         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
 324         disk_super->policy_hint_size = 0;
 325
 326         __copy_sm_root(cmd, disk_super);
 327
 328         disk_super->mapping_root = cpu_to_le64(cmd->root);
 329         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 330         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 331         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 332         disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
 333         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 334         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 335         disk_super->cache_blocks = cpu_to_le32(0);
 336
 337         disk_super->read_hits = cpu_to_le32(0);
 338         disk_super->read_misses = cpu_to_le32(0);
 339         disk_super->write_hits = cpu_to_le32(0);
 340         disk_super->write_misses = cpu_to_le32(0);
 341
 342         return dm_tm_commit(cmd->tm, sblock);
 343 }
 344
 345 static int __format_metadata(struct dm_cache_metadata *cmd)
 346 {
 347         int r;
 348
 349         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 350                                  &cmd->tm, &cmd->metadata_sm);
 351         if (r < 0) {
 352                 DMERR("tm_create_with_sm failed");
 353                 return r;
 354         }
 355
 356         __setup_mapping_info(cmd);
 357
 358         r = dm_array_empty(&cmd->info, &cmd->root);
 359         if (r < 0)
 360                 goto bad;
 361
 362         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 363
 364         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
 365         if (r < 0)
 366                 goto bad;
 367
 368         cmd->discard_block_size = 0;
 369         cmd->discard_nr_blocks = 0;
 370
 371         r = __write_initial_superblock(cmd);
 372         if (r)
 373                 goto bad;
 374
 375         cmd->clean_when_opened = true;
 376         return 0;
 377
 378 bad:
 379         dm_tm_destroy(cmd->tm);
 380         dm_sm_destroy(cmd->metadata_sm);
 381
 382         return r;
 383 }
 384
 385 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
 386                                      struct dm_cache_metadata *cmd)
 387 {
 388         uint32_t features;
 389
 390         features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
 391         if (features) {
 392                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 393                       (unsigned long)features);
 394                 return -EINVAL;
 395         }
 396
 397         /*
 398          * Check for read-only metadata to skip the following RDWR checks.
 399          */
 400         if (get_disk_ro(cmd->bdev->bd_disk))
 401                 return 0;
 402
 403         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
 404         if (features) {
 405                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 406                       (unsigned long)features);
 407                 return -EINVAL;
 408         }
 409
 410         return 0;
 411 }
 412
 413 static int __open_metadata(struct dm_cache_metadata *cmd)
 414 {
 415         int r;
 416         struct dm_block *sblock;
 417         struct cache_disk_superblock *disk_super;
 418         unsigned long sb_flags;
 419
 420         r = superblock_read_lock(cmd, &sblock);
 421         if (r < 0) {
 422                 DMERR("couldn't read lock superblock");
 423                 return r;
 424         }
 425
 426         disk_super = dm_block_data(sblock);
 427
 428         /* Verify the data block size hasn't changed */
 429         if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
 430                 DMERR("changing the data block size (from %u to %llu) is not supported",
 431                       le32_to_cpu(disk_super->data_block_size),
 432                       (unsigned long long)cmd->data_block_size);
 433                 r = -EINVAL;
 434                 goto bad;
 435         }
 436
 437         r = __check_incompat_features(disk_super, cmd);
 438         if (r < 0)
 439                 goto bad;
 440
 441         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 442                                disk_super->metadata_space_map_root,
 443                                sizeof(disk_super->metadata_space_map_root),
 444                                &cmd->tm, &cmd->metadata_sm);
 445         if (r < 0) {
 446                 DMERR("tm_open_with_sm failed");
 447                 goto bad;
 448         }
 449
 450         __setup_mapping_info(cmd);
 451         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 452         sb_flags = le32_to_cpu(disk_super->flags);
 453         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 454         return dm_bm_unlock(sblock);
 455
 456 bad:
 457         dm_bm_unlock(sblock);
 458         return r;
 459 }
 460
 461 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 462                                      bool format_device)
 463 {
 464         int r;
 465         bool unformatted = false;
 466
 467         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 468         if (r)
 469                 return r;
 470
 471         if (unformatted)
 472                 return format_device ? __format_metadata(cmd) : -EPERM;
 473
 474         return __open_metadata(cmd);
 475 }
 476
 477 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 478                                             bool may_format_device)
 479 {
 480         int r;
 481         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE,
 482                                           CACHE_METADATA_CACHE_SIZE,
 483                                           CACHE_MAX_CONCURRENT_LOCKS);
 484         if (IS_ERR(cmd->bm)) {
 485                 DMERR("could not create block manager");
 486                 return PTR_ERR(cmd->bm);
 487         }
 488
 489         r = __open_or_format_metadata(cmd, may_format_device);
 490         if (r)
 491                 dm_block_manager_destroy(cmd->bm);
 492
 493         return r;
 494 }
 495
 496 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
 497 {
 498         dm_sm_destroy(cmd->metadata_sm);
 499         dm_tm_destroy(cmd->tm);
 500         dm_block_manager_destroy(cmd->bm);
 501 }
 502
 503 typedef unsigned long (*flags_mutator)(unsigned long);
 504
 505 static void update_flags(struct cache_disk_superblock *disk_super,
 506                          flags_mutator mutator)
 507 {
 508         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 509         disk_super->flags = cpu_to_le32(sb_flags);
 510 }
 511
 512 static unsigned long set_clean_shutdown(unsigned long flags)
 513 {
 514         set_bit(CLEAN_SHUTDOWN, &flags);
 515         return flags;
 516 }
 517
 518 static unsigned long clear_clean_shutdown(unsigned long flags)
 519 {
 520         clear_bit(CLEAN_SHUTDOWN, &flags);
 521         return flags;
 522 }
 523
 524 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 525                                    struct cache_disk_superblock *disk_super)
 526 {
 527         cmd->root = le64_to_cpu(disk_super->mapping_root);
 528         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 529         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 530         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 531         cmd->discard_nr_blocks = to_oblock(le64_to_cpu(disk_super->discard_nr_blocks));
 532         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 533         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 534         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 535         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 536         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 537         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 538         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 539
 540         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 541         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 542         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 543         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 544
 545         cmd->changed = false;
 546 }
 547
 548 /*
 549  * The mutator updates the superblock flags.
 550  */
 551 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 552                                      flags_mutator mutator)
 553 {
 554         int r;
 555         struct cache_disk_superblock *disk_super;
 556         struct dm_block *sblock;
 557
 558         r = superblock_lock(cmd, &sblock);
 559         if (r)
 560                 return r;
 561
 562         disk_super = dm_block_data(sblock);
 563         update_flags(disk_super, mutator);
 564         read_superblock_fields(cmd, disk_super);
 565         dm_bm_unlock(sblock);
 566
 567         return dm_bm_flush(cmd->bm);
 568 }
 569
 570 static int __begin_transaction(struct dm_cache_metadata *cmd)
 571 {
 572         int r;
 573         struct cache_disk_superblock *disk_super;
 574         struct dm_block *sblock;
 575
 576         /*
 577          * We re-read the superblock every time.  Shouldn't need to do this
 578          * really.
 579          */
 580         r = superblock_read_lock(cmd, &sblock);
 581         if (r)
 582                 return r;
 583
 584         disk_super = dm_block_data(sblock);
 585         read_superblock_fields(cmd, disk_super);
 586         dm_bm_unlock(sblock);
 587
 588         return 0;
 589 }
 590
 591 static int __commit_transaction(struct dm_cache_metadata *cmd,
 592                                 flags_mutator mutator)
 593 {
 594         int r;
 595         struct cache_disk_superblock *disk_super;
 596         struct dm_block *sblock;
 597
 598         /*
 599          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 600          */
 601         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 602
 603         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 604                             &cmd->discard_root);
 605         if (r)
 606                 return r;
 607
 608         r = dm_tm_pre_commit(cmd->tm);
 609         if (r < 0)
 610                 return r;
 611
 612         r = __save_sm_root(cmd);
 613         if (r)
 614                 return r;
 615
 616         r = superblock_lock(cmd, &sblock);
 617         if (r)
 618                 return r;
 619
 620         disk_super = dm_block_data(sblock);
 621
 622         if (mutator)
 623                 update_flags(disk_super, mutator);
 624
 625         disk_super->mapping_root = cpu_to_le64(cmd->root);
 626         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 627         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 628         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 629         disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
 630         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 631         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 632         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 633         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 634         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 635
 636         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 637         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 638         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 639         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 640         __copy_sm_root(cmd, disk_super);
 641
 642         return dm_tm_commit(cmd->tm, sblock);
 643 }
 644
 645 /*----------------------------------------------------------------*/
 646
 647 /*
 648  * The mappings are held in a dm-array that has 64-bit values stored in
 649  * little-endian format.  The index is the cblock, the high 48bits of the
 650  * value are the oblock and the low 16 bit the flags.
 651  */
 652 #define FLAGS_MASK ((1 << 16) - 1)
 653
 654 static __le64 pack_value(dm_oblock_t block, unsigned flags)
 655 {
 656         uint64_t value = from_oblock(block);
 657         value <<= 16;
 658         value = value | (flags & FLAGS_MASK);
 659         return cpu_to_le64(value);
 660 }
 661
 662 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 663 {
 664         uint64_t value = le64_to_cpu(value_le);
 665         uint64_t b = value >> 16;
 666         *block = to_oblock(b);
 667         *flags = value & FLAGS_MASK;
 668 }
 669
 670 /*----------------------------------------------------------------*/
 671
 672 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 673                                                  sector_t data_block_size,
 674                                                  bool may_format_device,
 675                                                  size_t policy_hint_size)
 676 {
 677         int r;
 678         struct dm_cache_metadata *cmd;
 679
 680         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 681         if (!cmd) {
 682                 DMERR("could not allocate metadata struct");
 683                 return NULL;
 684         }
 685
 686         init_rwsem(&cmd->root_lock);
 687         cmd->bdev = bdev;
 688         cmd->data_block_size = data_block_size;
 689         cmd->cache_blocks = 0;
 690         cmd->policy_hint_size = policy_hint_size;
 691         cmd->changed = true;
 692
 693         r = __create_persistent_data_objects(cmd, may_format_device);
 694         if (r) {
 695                 kfree(cmd);
 696                 return ERR_PTR(r);
 697         }
 698
 699         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 700         if (r < 0) {
 701                 dm_cache_metadata_close(cmd);
 702                 return ERR_PTR(r);
 703         }
 704
 705         return cmd;
 706 }
 707
 708 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 709 {
 710         __destroy_persistent_data_objects(cmd);
 711         kfree(cmd);
 712 }
 713
 714 /*
 715  * Checks that the given cache block is either unmapped or clean.
 716  */
 717 static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
 718                                    bool *result)
 719 {
 720         int r;
 721         __le64 value;
 722         dm_oblock_t ob;
 723         unsigned flags;
 724
 725         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
 726         if (r) {
 727                 DMERR("block_unmapped_or_clean failed");
 728                 return r;
 729         }
 730
 731         unpack_value(value, &ob, &flags);
 732         *result = !((flags & M_VALID) && (flags & M_DIRTY));
 733
 734         return 0;
 735 }
 736
 737 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 738                                         dm_cblock_t begin, dm_cblock_t end,
 739                                         bool *result)
 740 {
 741         int r;
 742         *result = true;
 743
 744         while (begin != end) {
 745                 r = block_unmapped_or_clean(cmd, begin, result);
 746                 if (r)
 747                         return r;
 748
 749                 if (!*result) {
 750                         DMERR("cache block %llu is dirty",
 751                               (unsigned long long) from_cblock(begin));
 752                         return 0;
 753                 }
 754
 755                 begin = to_cblock(from_cblock(begin) + 1);
 756         }
 757
 758         return 0;
 759 }
 760
 761 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 762 {
 763         int r;
 764         bool clean;
 765         __le64 null_mapping = pack_value(0, 0);
 766
 767         down_write(&cmd->root_lock);
 768         __dm_bless_for_disk(&null_mapping);
 769
 770         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
 771                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
 772                 if (r) {
 773                         __dm_unbless_for_disk(&null_mapping);
 774                         goto out;
 775                 }
 776
 777                 if (!clean) {
 778                         DMERR("unable to shrink cache due to dirty blocks");
 779                         r = -EINVAL;
 780                         __dm_unbless_for_disk(&null_mapping);
 781                         goto out;
 782                 }
 783         }
 784
 785         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
 786                             from_cblock(new_cache_size),
 787                             &null_mapping, &cmd->root);
 788         if (!r)
 789                 cmd->cache_blocks = new_cache_size;
 790         cmd->changed = true;
 791
 792 out:
 793         up_write(&cmd->root_lock);
 794
 795         return r;
 796 }
 797
 798 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 799                                    sector_t discard_block_size,
 800                                    dm_oblock_t new_nr_entries)
 801 {
 802         int r;
 803
 804         down_write(&cmd->root_lock);
 805         r = dm_bitset_resize(&cmd->discard_info,
 806                              cmd->discard_root,
 807                              from_oblock(cmd->discard_nr_blocks),
 808                              from_oblock(new_nr_entries),
 809                              false, &cmd->discard_root);
 810         if (!r) {
 811                 cmd->discard_block_size = discard_block_size;
 812                 cmd->discard_nr_blocks = new_nr_entries;
 813         }
 814
 815         cmd->changed = true;
 816         up_write(&cmd->root_lock);
 817
 818         return r;
 819 }
 820
 821 static int __set_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
 822 {
 823         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
 824                                  from_oblock(b), &cmd->discard_root);
 825 }
 826
 827 static int __clear_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
 828 {
 829         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
 830                                    from_oblock(b), &cmd->discard_root);
 831 }
 832
 833 static int __is_discarded(struct dm_cache_metadata *cmd, dm_oblock_t b,
 834                           bool *is_discarded)
 835 {
 836         return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
 837                                   from_oblock(b), &cmd->discard_root,
 838                                   is_discarded);
 839 }
 840
 841 static int __discard(struct dm_cache_metadata *cmd,
 842                      dm_oblock_t dblock, bool discard)
 843 {
 844         int r;
 845
 846         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
 847         if (r)
 848                 return r;
 849
 850         cmd->changed = true;
 851         return 0;
 852 }
 853
 854 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
 855                          dm_oblock_t dblock, bool discard)
 856 {
 857         int r;
 858
 859         down_write(&cmd->root_lock);
 860         r = __discard(cmd, dblock, discard);
 861         up_write(&cmd->root_lock);
 862
 863         return r;
 864 }
 865
 866 static int __load_discards(struct dm_cache_metadata *cmd,
 867                            load_discard_fn fn, void *context)
 868 {
 869         int r = 0;
 870         dm_block_t b;
 871         bool discard;
 872
 873         for (b = 0; b < from_oblock(cmd->discard_nr_blocks); b++) {
 874                 dm_oblock_t dblock = to_oblock(b);
 875
 876                 if (cmd->clean_when_opened) {
 877                         r = __is_discarded(cmd, dblock, &discard);
 878                         if (r)
 879                                 return r;
 880                 } else
 881                         discard = false;
 882
 883                 r = fn(context, cmd->discard_block_size, dblock, discard);
 884                 if (r)
 885                         break;
 886         }
 887
 888         return r;
 889 }
 890
 891 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
 892                            load_discard_fn fn, void *context)
 893 {
 894         int r;
 895
 896         down_read(&cmd->root_lock);
 897         r = __load_discards(cmd, fn, context);
 898         up_read(&cmd->root_lock);
 899
 900         return r;
 901 }
 902
 903 dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd)
 904 {
 905         dm_cblock_t r;
 906
 907         down_read(&cmd->root_lock);
 908         r = cmd->cache_blocks;
 909         up_read(&cmd->root_lock);
 910
 911         return r;
 912 }
 913
 914 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
 915 {
 916         int r;
 917         __le64 value = pack_value(0, 0);
 918
 919         __dm_bless_for_disk(&value);
 920         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
 921                                &value, &cmd->root);
 922         if (r)
 923                 return r;
 924
 925         cmd->changed = true;
 926         return 0;
 927 }
 928
 929 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
 930 {
 931         int r;
 932
 933         down_write(&cmd->root_lock);
 934         r = __remove(cmd, cblock);
 935         up_write(&cmd->root_lock);
 936
 937         return r;
 938 }
 939
 940 static int __insert(struct dm_cache_metadata *cmd,
 941                     dm_cblock_t cblock, dm_oblock_t oblock)
 942 {
 943         int r;
 944         __le64 value = pack_value(oblock, M_VALID);
 945         __dm_bless_for_disk(&value);
 946
 947         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
 948                                &value, &cmd->root);
 949         if (r)
 950                 return r;
 951
 952         cmd->changed = true;
 953         return 0;
 954 }
 955
 956 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
 957                             dm_cblock_t cblock, dm_oblock_t oblock)
 958 {
 959         int r;
 960
 961         down_write(&cmd->root_lock);
 962         r = __insert(cmd, cblock, oblock);
 963         up_write(&cmd->root_lock);
 964
 965         return r;
 966 }
 967
 968 struct thunk {
 969         load_mapping_fn fn;
 970         void *context;
 971
 972         struct dm_cache_metadata *cmd;
 973         bool respect_dirty_flags;
 974         bool hints_valid;
 975 };
 976
 977 static bool policy_unchanged(struct dm_cache_metadata *cmd,
 978                              struct dm_cache_policy *policy)
 979 {
 980         const char *policy_name = dm_cache_policy_get_name(policy);
 981         const unsigned *policy_version = dm_cache_policy_get_version(policy);
 982         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
 983
 984         /*
 985          * Ensure policy names match.
 986          */
 987         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
 988                 return false;
 989
 990         /*
 991          * Ensure policy major versions match.
 992          */
 993         if (cmd->policy_version[0] != policy_version[0])
 994                 return false;
 995
 996         /*
 997          * Ensure policy hint sizes match.
 998          */
 999         if (cmd->policy_hint_size != policy_hint_size)
1000                 return false;
1001
1002         return true;
1003 }
1004
1005 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1006 {
1007         return cmd->hint_root && cmd->policy_hint_size;
1008 }
1009
1010 static bool hints_array_available(struct dm_cache_metadata *cmd,
1011                                   struct dm_cache_policy *policy)
1012 {
1013         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1014                 hints_array_initialized(cmd);
1015 }
1016
1017 static int __load_mapping(void *context, uint64_t cblock, void *leaf)
1018 {
1019         int r = 0;
1020         bool dirty;
1021         __le64 value;
1022         __le32 hint_value = 0;
1023         dm_oblock_t oblock;
1024         unsigned flags;
1025         struct thunk *thunk = context;
1026         struct dm_cache_metadata *cmd = thunk->cmd;
1027
1028         memcpy(&value, leaf, sizeof(value));
1029         unpack_value(value, &oblock, &flags);
1030
1031         if (flags & M_VALID) {
1032                 if (thunk->hints_valid) {
1033                         r = dm_array_get_value(&cmd->hint_info, cmd->hint_root,
1034                                                cblock, &hint_value);
1035                         if (r && r != -ENODATA)
1036                                 return r;
1037                 }
1038
1039                 dirty = thunk->respect_dirty_flags ? (flags & M_DIRTY) : true;
1040                 r = thunk->fn(thunk->context, oblock, to_cblock(cblock),
1041                               dirty, le32_to_cpu(hint_value), thunk->hints_valid);
1042         }
1043
1044         return r;
1045 }
1046
1047 static int __load_mappings(struct dm_cache_metadata *cmd,
1048                            struct dm_cache_policy *policy,
1049                            load_mapping_fn fn, void *context)
1050 {
1051         struct thunk thunk;
1052
1053         thunk.fn = fn;
1054         thunk.context = context;
1055
1056         thunk.cmd = cmd;
1057         thunk.respect_dirty_flags = cmd->clean_when_opened;
1058         thunk.hints_valid = hints_array_available(cmd, policy);
1059
1060         return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
1061 }
1062
1063 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1064                            struct dm_cache_policy *policy,
1065                            load_mapping_fn fn, void *context)
1066 {
1067         int r;
1068
1069         down_read(&cmd->root_lock);
1070         r = __load_mappings(cmd, policy, fn, context);
1071         up_read(&cmd->root_lock);
1072
1073         return r;
1074 }
1075
1076 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1077 {
1078         int r = 0;
1079         __le64 value;
1080         dm_oblock_t oblock;
1081         unsigned flags;
1082
1083         memcpy(&value, leaf, sizeof(value));
1084         unpack_value(value, &oblock, &flags);
1085
1086         return r;
1087 }
1088
1089 static int __dump_mappings(struct dm_cache_metadata *cmd)
1090 {
1091         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1092 }
1093
1094 void dm_cache_dump(struct dm_cache_metadata *cmd)
1095 {
1096         down_read(&cmd->root_lock);
1097         __dump_mappings(cmd);
1098         up_read(&cmd->root_lock);
1099 }
1100
1101 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1102 {
1103         int r;
1104
1105         down_read(&cmd->root_lock);
1106         r = cmd->changed;
1107         up_read(&cmd->root_lock);
1108
1109         return r;
1110 }
1111
1112 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1113 {
1114         int r;
1115         unsigned flags;
1116         dm_oblock_t oblock;
1117         __le64 value;
1118
1119         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1120         if (r)
1121                 return r;
1122
1123         unpack_value(value, &oblock, &flags);
1124
1125         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1126                 /* nothing to be done */
1127                 return 0;
1128
1129         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1130         __dm_bless_for_disk(&value);
1131
1132         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1133                                &value, &cmd->root);
1134         if (r)
1135                 return r;
1136
1137         cmd->changed = true;
1138         return 0;
1139
1140 }
1141
1142 int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
1143                        dm_cblock_t cblock, bool dirty)
1144 {
1145         int r;
1146
1147         down_write(&cmd->root_lock);
1148         r = __dirty(cmd, cblock, dirty);
1149         up_write(&cmd->root_lock);
1150
1151         return r;
1152 }
1153
1154 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1155                                  struct dm_cache_statistics *stats)
1156 {
1157         down_read(&cmd->root_lock);
1158         *stats = cmd->stats;
1159         up_read(&cmd->root_lock);
1160 }
1161
1162 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1163                                  struct dm_cache_statistics *stats)
1164 {
1165         down_write(&cmd->root_lock);
1166         cmd->stats = *stats;
1167         up_write(&cmd->root_lock);
1168 }
1169
1170 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1171 {
1172         int r;
1173         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1174                                  clear_clean_shutdown);
1175
1176         down_write(&cmd->root_lock);
1177         r = __commit_transaction(cmd, mutator);
1178         if (r)
1179                 goto out;
1180
1181         r = __begin_transaction(cmd);
1182
1183 out:
1184         up_write(&cmd->root_lock);
1185         return r;
1186 }
1187
1188 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1189                                            dm_block_t *result)
1190 {
1191         int r = -EINVAL;
1192
1193         down_read(&cmd->root_lock);
1194         r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1195         up_read(&cmd->root_lock);
1196
1197         return r;
1198 }
1199
1200 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1201                                    dm_block_t *result)
1202 {
1203         int r = -EINVAL;
1204
1205         down_read(&cmd->root_lock);
1206         r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1207         up_read(&cmd->root_lock);
1208
1209         return r;
1210 }
1211
1212 /*----------------------------------------------------------------*/
1213
1214 static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1215 {
1216         int r;
1217         __le32 value;
1218         size_t hint_size;
1219         const char *policy_name = dm_cache_policy_get_name(policy);
1220         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1221
1222         if (!policy_name[0] ||
1223             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1224                 return -EINVAL;
1225
1226         if (!policy_unchanged(cmd, policy)) {
1227                 strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1228                 memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1229
1230                 hint_size = dm_cache_policy_get_hint_size(policy);
1231                 if (!hint_size)
1232                         return 0; /* short-circuit hints initialization */
1233                 cmd->policy_hint_size = hint_size;
1234
1235                 if (cmd->hint_root) {
1236                         r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1237                         if (r)
1238                                 return r;
1239                 }
1240
1241                 r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
1242                 if (r)
1243                         return r;
1244
1245                 value = cpu_to_le32(0);
1246                 __dm_bless_for_disk(&value);
1247                 r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
1248                                     from_cblock(cmd->cache_blocks),
1249                                     &value, &cmd->hint_root);
1250                 if (r)
1251                         return r;
1252         }
1253
1254         return 0;
1255 }
1256
1257 static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)
1258 {
1259         struct dm_cache_metadata *cmd = context;
1260         __le32 value = cpu_to_le32(hint);
1261         int r;
1262
1263         __dm_bless_for_disk(&value);
1264
1265         r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
1266                                from_cblock(cblock), &value, &cmd->hint_root);
1267         cmd->changed = true;
1268
1269         return r;
1270 }
1271
1272 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1273 {
1274         int r;
1275
1276         r = begin_hints(cmd, policy);
1277         if (r) {
1278                 DMERR("begin_hints failed");
1279                 return r;
1280         }
1281
1282         return policy_walk_mappings(policy, save_hint, cmd);
1283 }
1284
1285 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1286 {
1287         int r;
1288
1289         down_write(&cmd->root_lock);
1290         r = write_hints(cmd, policy);
1291         up_write(&cmd->root_lock);
1292
1293         return r;
1294 }
1295
1296 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1297 {
1298         return blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1299 }