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         r = __check_incompat_features(disk_super, cmd);
 429         if (r < 0)
 430                 goto bad;
 431
 432         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 433                                disk_super->metadata_space_map_root,
 434                                sizeof(disk_super->metadata_space_map_root),
 435                                &cmd->tm, &cmd->metadata_sm);
 436         if (r < 0) {
 437                 DMERR("tm_open_with_sm failed");
 438                 goto bad;
 439         }
 440
 441         __setup_mapping_info(cmd);
 442         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 443         sb_flags = le32_to_cpu(disk_super->flags);
 444         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 445         return dm_bm_unlock(sblock);
 446
 447 bad:
 448         dm_bm_unlock(sblock);
 449         return r;
 450 }
 451
 452 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 453                                      bool format_device)
 454 {
 455         int r;
 456         bool unformatted = false;
 457
 458         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 459         if (r)
 460                 return r;
 461
 462         if (unformatted)
 463                 return format_device ? __format_metadata(cmd) : -EPERM;
 464
 465         return __open_metadata(cmd);
 466 }
 467
 468 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 469                                             bool may_format_device)
 470 {
 471         int r;
 472         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE,
 473                                           CACHE_METADATA_CACHE_SIZE,
 474                                           CACHE_MAX_CONCURRENT_LOCKS);
 475         if (IS_ERR(cmd->bm)) {
 476                 DMERR("could not create block manager");
 477                 return PTR_ERR(cmd->bm);
 478         }
 479
 480         r = __open_or_format_metadata(cmd, may_format_device);
 481         if (r)
 482                 dm_block_manager_destroy(cmd->bm);
 483
 484         return r;
 485 }
 486
 487 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
 488 {
 489         dm_sm_destroy(cmd->metadata_sm);
 490         dm_tm_destroy(cmd->tm);
 491         dm_block_manager_destroy(cmd->bm);
 492 }
 493
 494 typedef unsigned long (*flags_mutator)(unsigned long);
 495
 496 static void update_flags(struct cache_disk_superblock *disk_super,
 497                          flags_mutator mutator)
 498 {
 499         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 500         disk_super->flags = cpu_to_le32(sb_flags);
 501 }
 502
 503 static unsigned long set_clean_shutdown(unsigned long flags)
 504 {
 505         set_bit(CLEAN_SHUTDOWN, &flags);
 506         return flags;
 507 }
 508
 509 static unsigned long clear_clean_shutdown(unsigned long flags)
 510 {
 511         clear_bit(CLEAN_SHUTDOWN, &flags);
 512         return flags;
 513 }
 514
 515 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 516                                    struct cache_disk_superblock *disk_super)
 517 {
 518         cmd->root = le64_to_cpu(disk_super->mapping_root);
 519         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 520         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 521         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 522         cmd->discard_nr_blocks = to_oblock(le64_to_cpu(disk_super->discard_nr_blocks));
 523         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 524         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 525         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 526         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 527         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 528         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 529         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 530
 531         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 532         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 533         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 534         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 535
 536         cmd->changed = false;
 537 }
 538
 539 /*
 540  * The mutator updates the superblock flags.
 541  */
 542 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 543                                      flags_mutator mutator)
 544 {
 545         int r;
 546         struct cache_disk_superblock *disk_super;
 547         struct dm_block *sblock;
 548
 549         r = superblock_lock(cmd, &sblock);
 550         if (r)
 551                 return r;
 552
 553         disk_super = dm_block_data(sblock);
 554         update_flags(disk_super, mutator);
 555         read_superblock_fields(cmd, disk_super);
 556         dm_bm_unlock(sblock);
 557
 558         return dm_bm_flush(cmd->bm);
 559 }
 560
 561 static int __begin_transaction(struct dm_cache_metadata *cmd)
 562 {
 563         int r;
 564         struct cache_disk_superblock *disk_super;
 565         struct dm_block *sblock;
 566
 567         /*
 568          * We re-read the superblock every time.  Shouldn't need to do this
 569          * really.
 570          */
 571         r = superblock_read_lock(cmd, &sblock);
 572         if (r)
 573                 return r;
 574
 575         disk_super = dm_block_data(sblock);
 576         read_superblock_fields(cmd, disk_super);
 577         dm_bm_unlock(sblock);
 578
 579         return 0;
 580 }
 581
 582 static int __commit_transaction(struct dm_cache_metadata *cmd,
 583                                 flags_mutator mutator)
 584 {
 585         int r;
 586         struct cache_disk_superblock *disk_super;
 587         struct dm_block *sblock;
 588
 589         /*
 590          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 591          */
 592         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 593
 594         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 595                             &cmd->discard_root);
 596         if (r)
 597                 return r;
 598
 599         r = dm_tm_pre_commit(cmd->tm);
 600         if (r < 0)
 601                 return r;
 602
 603         r = __save_sm_root(cmd);
 604         if (r)
 605                 return r;
 606
 607         r = superblock_lock(cmd, &sblock);
 608         if (r)
 609                 return r;
 610
 611         disk_super = dm_block_data(sblock);
 612
 613         if (mutator)
 614                 update_flags(disk_super, mutator);
 615
 616         disk_super->mapping_root = cpu_to_le64(cmd->root);
 617         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 618         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 619         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 620         disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
 621         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 622         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 623         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 624         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 625         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 626
 627         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 628         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 629         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 630         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 631         __copy_sm_root(cmd, disk_super);
 632
 633         return dm_tm_commit(cmd->tm, sblock);
 634 }
 635
 636 /*----------------------------------------------------------------*/
 637
 638 /*
 639  * The mappings are held in a dm-array that has 64-bit values stored in
 640  * little-endian format.  The index is the cblock, the high 48bits of the
 641  * value are the oblock and the low 16 bit the flags.
 642  */
 643 #define FLAGS_MASK ((1 << 16) - 1)
 644
 645 static __le64 pack_value(dm_oblock_t block, unsigned flags)
 646 {
 647         uint64_t value = from_oblock(block);
 648         value <<= 16;
 649         value = value | (flags & FLAGS_MASK);
 650         return cpu_to_le64(value);
 651 }
 652
 653 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 654 {
 655         uint64_t value = le64_to_cpu(value_le);
 656         uint64_t b = value >> 16;
 657         *block = to_oblock(b);
 658         *flags = value & FLAGS_MASK;
 659 }
 660
 661 /*----------------------------------------------------------------*/
 662
 663 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 664                                                  sector_t data_block_size,
 665                                                  bool may_format_device,
 666                                                  size_t policy_hint_size)
 667 {
 668         int r;
 669         struct dm_cache_metadata *cmd;
 670
 671         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 672         if (!cmd) {
 673                 DMERR("could not allocate metadata struct");
 674                 return NULL;
 675         }
 676
 677         init_rwsem(&cmd->root_lock);
 678         cmd->bdev = bdev;
 679         cmd->data_block_size = data_block_size;
 680         cmd->cache_blocks = 0;
 681         cmd->policy_hint_size = policy_hint_size;
 682         cmd->changed = true;
 683
 684         r = __create_persistent_data_objects(cmd, may_format_device);
 685         if (r) {
 686                 kfree(cmd);
 687                 return ERR_PTR(r);
 688         }
 689
 690         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 691         if (r < 0) {
 692                 dm_cache_metadata_close(cmd);
 693                 return ERR_PTR(r);
 694         }
 695
 696         return cmd;
 697 }
 698
 699 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 700 {
 701         __destroy_persistent_data_objects(cmd);
 702         kfree(cmd);
 703 }
 704
 705 /*
 706  * Checks that the given cache block is either unmapped or clean.
 707  */
 708 static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
 709                                    bool *result)
 710 {
 711         int r;
 712         __le64 value;
 713         dm_oblock_t ob;
 714         unsigned flags;
 715
 716         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
 717         if (r) {
 718                 DMERR("block_unmapped_or_clean failed");
 719                 return r;
 720         }
 721
 722         unpack_value(value, &ob, &flags);
 723         *result = !((flags & M_VALID) && (flags & M_DIRTY));
 724
 725         return 0;
 726 }
 727
 728 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 729                                         dm_cblock_t begin, dm_cblock_t end,
 730                                         bool *result)
 731 {
 732         int r;
 733         *result = true;
 734
 735         while (begin != end) {
 736                 r = block_unmapped_or_clean(cmd, begin, result);
 737                 if (r)
 738                         return r;
 739
 740                 if (!*result) {
 741                         DMERR("cache block %llu is dirty",
 742                               (unsigned long long) from_cblock(begin));
 743                         return 0;
 744                 }
 745
 746                 begin = to_cblock(from_cblock(begin) + 1);
 747         }
 748
 749         return 0;
 750 }
 751
 752 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 753 {
 754         int r;
 755         bool clean;
 756         __le64 null_mapping = pack_value(0, 0);
 757
 758         down_write(&cmd->root_lock);
 759         __dm_bless_for_disk(&null_mapping);
 760
 761         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
 762                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
 763                 if (r) {
 764                         __dm_unbless_for_disk(&null_mapping);
 765                         goto out;
 766                 }
 767
 768                 if (!clean) {
 769                         DMERR("unable to shrink cache due to dirty blocks");
 770                         r = -EINVAL;
 771                         __dm_unbless_for_disk(&null_mapping);
 772                         goto out;
 773                 }
 774         }
 775
 776         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
 777                             from_cblock(new_cache_size),
 778                             &null_mapping, &cmd->root);
 779         if (!r)
 780                 cmd->cache_blocks = new_cache_size;
 781         cmd->changed = true;
 782
 783 out:
 784         up_write(&cmd->root_lock);
 785
 786         return r;
 787 }
 788
 789 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 790                                    sector_t discard_block_size,
 791                                    dm_oblock_t new_nr_entries)
 792 {
 793         int r;
 794
 795         down_write(&cmd->root_lock);
 796         r = dm_bitset_resize(&cmd->discard_info,
 797                              cmd->discard_root,
 798                              from_oblock(cmd->discard_nr_blocks),
 799                              from_oblock(new_nr_entries),
 800                              false, &cmd->discard_root);
 801         if (!r) {
 802                 cmd->discard_block_size = discard_block_size;
 803                 cmd->discard_nr_blocks = new_nr_entries;
 804         }
 805
 806         cmd->changed = true;
 807         up_write(&cmd->root_lock);
 808
 809         return r;
 810 }
 811
 812 static int __set_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
 813 {
 814         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
 815                                  from_oblock(b), &cmd->discard_root);
 816 }
 817
 818 static int __clear_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
 819 {
 820         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
 821                                    from_oblock(b), &cmd->discard_root);
 822 }
 823
 824 static int __is_discarded(struct dm_cache_metadata *cmd, dm_oblock_t b,
 825                           bool *is_discarded)
 826 {
 827         return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
 828                                   from_oblock(b), &cmd->discard_root,
 829                                   is_discarded);
 830 }
 831
 832 static int __discard(struct dm_cache_metadata *cmd,
 833                      dm_oblock_t dblock, bool discard)
 834 {
 835         int r;
 836
 837         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
 838         if (r)
 839                 return r;
 840
 841         cmd->changed = true;
 842         return 0;
 843 }
 844
 845 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
 846                          dm_oblock_t dblock, bool discard)
 847 {
 848         int r;
 849
 850         down_write(&cmd->root_lock);
 851         r = __discard(cmd, dblock, discard);
 852         up_write(&cmd->root_lock);
 853
 854         return r;
 855 }
 856
 857 static int __load_discards(struct dm_cache_metadata *cmd,
 858                            load_discard_fn fn, void *context)
 859 {
 860         int r = 0;
 861         dm_block_t b;
 862         bool discard;
 863
 864         for (b = 0; b < from_oblock(cmd->discard_nr_blocks); b++) {
 865                 dm_oblock_t dblock = to_oblock(b);
 866
 867                 if (cmd->clean_when_opened) {
 868                         r = __is_discarded(cmd, dblock, &discard);
 869                         if (r)
 870                                 return r;
 871                 } else
 872                         discard = false;
 873
 874                 r = fn(context, cmd->discard_block_size, dblock, discard);
 875                 if (r)
 876                         break;
 877         }
 878
 879         return r;
 880 }
 881
 882 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
 883                            load_discard_fn fn, void *context)
 884 {
 885         int r;
 886
 887         down_read(&cmd->root_lock);
 888         r = __load_discards(cmd, fn, context);
 889         up_read(&cmd->root_lock);
 890
 891         return r;
 892 }
 893
 894 dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd)
 895 {
 896         dm_cblock_t r;
 897
 898         down_read(&cmd->root_lock);
 899         r = cmd->cache_blocks;
 900         up_read(&cmd->root_lock);
 901
 902         return r;
 903 }
 904
 905 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
 906 {
 907         int r;
 908         __le64 value = pack_value(0, 0);
 909
 910         __dm_bless_for_disk(&value);
 911         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
 912                                &value, &cmd->root);
 913         if (r)
 914                 return r;
 915
 916         cmd->changed = true;
 917         return 0;
 918 }
 919
 920 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
 921 {
 922         int r;
 923
 924         down_write(&cmd->root_lock);
 925         r = __remove(cmd, cblock);
 926         up_write(&cmd->root_lock);
 927
 928         return r;
 929 }
 930
 931 static int __insert(struct dm_cache_metadata *cmd,
 932                     dm_cblock_t cblock, dm_oblock_t oblock)
 933 {
 934         int r;
 935         __le64 value = pack_value(oblock, M_VALID);
 936         __dm_bless_for_disk(&value);
 937
 938         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
 939                                &value, &cmd->root);
 940         if (r)
 941                 return r;
 942
 943         cmd->changed = true;
 944         return 0;
 945 }
 946
 947 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
 948                             dm_cblock_t cblock, dm_oblock_t oblock)
 949 {
 950         int r;
 951
 952         down_write(&cmd->root_lock);
 953         r = __insert(cmd, cblock, oblock);
 954         up_write(&cmd->root_lock);
 955
 956         return r;
 957 }
 958
 959 struct thunk {
 960         load_mapping_fn fn;
 961         void *context;
 962
 963         struct dm_cache_metadata *cmd;
 964         bool respect_dirty_flags;
 965         bool hints_valid;
 966 };
 967
 968 static bool policy_unchanged(struct dm_cache_metadata *cmd,
 969                              struct dm_cache_policy *policy)
 970 {
 971         const char *policy_name = dm_cache_policy_get_name(policy);
 972         const unsigned *policy_version = dm_cache_policy_get_version(policy);
 973         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
 974
 975         /*
 976          * Ensure policy names match.
 977          */
 978         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
 979                 return false;
 980
 981         /*
 982          * Ensure policy major versions match.
 983          */
 984         if (cmd->policy_version[0] != policy_version[0])
 985                 return false;
 986
 987         /*
 988          * Ensure policy hint sizes match.
 989          */
 990         if (cmd->policy_hint_size != policy_hint_size)
 991                 return false;
 992
 993         return true;
 994 }
 995
 996 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
 997 {
 998         return cmd->hint_root && cmd->policy_hint_size;
 999 }
1000
1001 static bool hints_array_available(struct dm_cache_metadata *cmd,
1002                                   struct dm_cache_policy *policy)
1003 {
1004         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1005                 hints_array_initialized(cmd);
1006 }
1007
1008 static int __load_mapping(void *context, uint64_t cblock, void *leaf)
1009 {
1010         int r = 0;
1011         bool dirty;
1012         __le64 value;
1013         __le32 hint_value = 0;
1014         dm_oblock_t oblock;
1015         unsigned flags;
1016         struct thunk *thunk = context;
1017         struct dm_cache_metadata *cmd = thunk->cmd;
1018
1019         memcpy(&value, leaf, sizeof(value));
1020         unpack_value(value, &oblock, &flags);
1021
1022         if (flags & M_VALID) {
1023                 if (thunk->hints_valid) {
1024                         r = dm_array_get_value(&cmd->hint_info, cmd->hint_root,
1025                                                cblock, &hint_value);
1026                         if (r && r != -ENODATA)
1027                                 return r;
1028                 }
1029
1030                 dirty = thunk->respect_dirty_flags ? (flags & M_DIRTY) : true;
1031                 r = thunk->fn(thunk->context, oblock, to_cblock(cblock),
1032                               dirty, le32_to_cpu(hint_value), thunk->hints_valid);
1033         }
1034
1035         return r;
1036 }
1037
1038 static int __load_mappings(struct dm_cache_metadata *cmd,
1039                            struct dm_cache_policy *policy,
1040                            load_mapping_fn fn, void *context)
1041 {
1042         struct thunk thunk;
1043
1044         thunk.fn = fn;
1045         thunk.context = context;
1046
1047         thunk.cmd = cmd;
1048         thunk.respect_dirty_flags = cmd->clean_when_opened;
1049         thunk.hints_valid = hints_array_available(cmd, policy);
1050
1051         return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
1052 }
1053
1054 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1055                            struct dm_cache_policy *policy,
1056                            load_mapping_fn fn, void *context)
1057 {
1058         int r;
1059
1060         down_read(&cmd->root_lock);
1061         r = __load_mappings(cmd, policy, fn, context);
1062         up_read(&cmd->root_lock);
1063
1064         return r;
1065 }
1066
1067 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1068 {
1069         int r = 0;
1070         __le64 value;
1071         dm_oblock_t oblock;
1072         unsigned flags;
1073
1074         memcpy(&value, leaf, sizeof(value));
1075         unpack_value(value, &oblock, &flags);
1076
1077         return r;
1078 }
1079
1080 static int __dump_mappings(struct dm_cache_metadata *cmd)
1081 {
1082         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1083 }
1084
1085 void dm_cache_dump(struct dm_cache_metadata *cmd)
1086 {
1087         down_read(&cmd->root_lock);
1088         __dump_mappings(cmd);
1089         up_read(&cmd->root_lock);
1090 }
1091
1092 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1093 {
1094         int r;
1095
1096         down_read(&cmd->root_lock);
1097         r = cmd->changed;
1098         up_read(&cmd->root_lock);
1099
1100         return r;
1101 }
1102
1103 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1104 {
1105         int r;
1106         unsigned flags;
1107         dm_oblock_t oblock;
1108         __le64 value;
1109
1110         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1111         if (r)
1112                 return r;
1113
1114         unpack_value(value, &oblock, &flags);
1115
1116         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1117                 /* nothing to be done */
1118                 return 0;
1119
1120         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1121         __dm_bless_for_disk(&value);
1122
1123         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1124                                &value, &cmd->root);
1125         if (r)
1126                 return r;
1127
1128         cmd->changed = true;
1129         return 0;
1130
1131 }
1132
1133 int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
1134                        dm_cblock_t cblock, bool dirty)
1135 {
1136         int r;
1137
1138         down_write(&cmd->root_lock);
1139         r = __dirty(cmd, cblock, dirty);
1140         up_write(&cmd->root_lock);
1141
1142         return r;
1143 }
1144
1145 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1146                                  struct dm_cache_statistics *stats)
1147 {
1148         down_read(&cmd->root_lock);
1149         *stats = cmd->stats;
1150         up_read(&cmd->root_lock);
1151 }
1152
1153 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1154                                  struct dm_cache_statistics *stats)
1155 {
1156         down_write(&cmd->root_lock);
1157         cmd->stats = *stats;
1158         up_write(&cmd->root_lock);
1159 }
1160
1161 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1162 {
1163         int r;
1164         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1165                                  clear_clean_shutdown);
1166
1167         down_write(&cmd->root_lock);
1168         r = __commit_transaction(cmd, mutator);
1169         if (r)
1170                 goto out;
1171
1172         r = __begin_transaction(cmd);
1173
1174 out:
1175         up_write(&cmd->root_lock);
1176         return r;
1177 }
1178
1179 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1180                                            dm_block_t *result)
1181 {
1182         int r = -EINVAL;
1183
1184         down_read(&cmd->root_lock);
1185         r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1186         up_read(&cmd->root_lock);
1187
1188         return r;
1189 }
1190
1191 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1192                                    dm_block_t *result)
1193 {
1194         int r = -EINVAL;
1195
1196         down_read(&cmd->root_lock);
1197         r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1198         up_read(&cmd->root_lock);
1199
1200         return r;
1201 }
1202
1203 /*----------------------------------------------------------------*/
1204
1205 static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1206 {
1207         int r;
1208         __le32 value;
1209         size_t hint_size;
1210         const char *policy_name = dm_cache_policy_get_name(policy);
1211         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1212
1213         if (!policy_name[0] ||
1214             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1215                 return -EINVAL;
1216
1217         if (!policy_unchanged(cmd, policy)) {
1218                 strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1219                 memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1220
1221                 hint_size = dm_cache_policy_get_hint_size(policy);
1222                 if (!hint_size)
1223                         return 0; /* short-circuit hints initialization */
1224                 cmd->policy_hint_size = hint_size;
1225
1226                 if (cmd->hint_root) {
1227                         r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1228                         if (r)
1229                                 return r;
1230                 }
1231
1232                 r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
1233                 if (r)
1234                         return r;
1235
1236                 value = cpu_to_le32(0);
1237                 __dm_bless_for_disk(&value);
1238                 r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
1239                                     from_cblock(cmd->cache_blocks),
1240                                     &value, &cmd->hint_root);
1241                 if (r)
1242                         return r;
1243         }
1244
1245         return 0;
1246 }
1247
1248 static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)
1249 {
1250         struct dm_cache_metadata *cmd = context;
1251         __le32 value = cpu_to_le32(hint);
1252         int r;
1253
1254         __dm_bless_for_disk(&value);
1255
1256         r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
1257                                from_cblock(cblock), &value, &cmd->hint_root);
1258         cmd->changed = true;
1259
1260         return r;
1261 }
1262
1263 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1264 {
1265         int r;
1266
1267         r = begin_hints(cmd, policy);
1268         if (r) {
1269                 DMERR("begin_hints failed");
1270                 return r;
1271         }
1272
1273         return policy_walk_mappings(policy, save_hint, cmd);
1274 }
1275
1276 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1277 {
1278         int r;
1279
1280         down_write(&cmd->root_lock);
1281         r = write_hints(cmd, policy);
1282         up_write(&cmd->root_lock);
1283
1284         return r;
1285 }
1286
1287 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1288 {
1289         return blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1290 }