drivers/md/dm-thin-metadata.c

   1 /*
   2  * Copyright (C) 2011-2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-thin-metadata.h"
   8 #include "persistent-data/dm-btree.h"
   9 #include "persistent-data/dm-space-map.h"
  10 #include "persistent-data/dm-space-map-disk.h"
  11 #include "persistent-data/dm-transaction-manager.h"
  12
  13 #include <linux/list.h>
  14 #include <linux/device-mapper.h>
  15 #include <linux/workqueue.h>
  16
  17 /*--------------------------------------------------------------------------
  18  * As far as the metadata goes, there is:
  19  *
  20  * - A superblock in block zero, taking up fewer than 512 bytes for
  21  *   atomic writes.
  22  *
  23  * - A space map managing the metadata blocks.
  24  *
  25  * - A space map managing the data blocks.
  26  *
  27  * - A btree mapping our internal thin dev ids onto struct disk_device_details.
  28  *
  29  * - A hierarchical btree, with 2 levels which effectively maps (thin
  30  *   dev id, virtual block) -> block_time.  Block time is a 64-bit
  31  *   field holding the time in the low 24 bits, and block in the top 48
  32  *   bits.
  33  *
  34  * BTrees consist solely of btree_nodes, that fill a block.  Some are
  35  * internal nodes, as such their values are a __le64 pointing to other
  36  * nodes.  Leaf nodes can store data of any reasonable size (ie. much
  37  * smaller than the block size).  The nodes consist of the header,
  38  * followed by an array of keys, followed by an array of values.  We have
  39  * to binary search on the keys so they're all held together to help the
  40  * cpu cache.
  41  *
  42  * Space maps have 2 btrees:
  43  *
  44  * - One maps a uint64_t onto a struct index_entry.  Which points to a
  45  *   bitmap block, and has some details about how many free entries there
  46  *   are etc.
  47  *
  48  * - The bitmap blocks have a header (for the checksum).  Then the rest
  49  *   of the block is pairs of bits.  With the meaning being:
  50  *
  51  *   0 - ref count is 0
  52  *   1 - ref count is 1
  53  *   2 - ref count is 2
  54  *   3 - ref count is higher than 2
  55  *
  56  * - If the count is higher than 2 then the ref count is entered in a
  57  *   second btree that directly maps the block_address to a uint32_t ref
  58  *   count.
  59  *
  60  * The space map metadata variant doesn't have a bitmaps btree.  Instead
  61  * it has one single blocks worth of index_entries.  This avoids
  62  * recursive issues with the bitmap btree needing to allocate space in
  63  * order to insert.  With a small data block size such as 64k the
  64  * metadata support data devices that are hundreds of terrabytes.
  65  *
  66  * The space maps allocate space linearly from front to back.  Space that
  67  * is freed in a transaction is never recycled within that transaction.
  68  * To try and avoid fragmenting _free_ space the allocator always goes
  69  * back and fills in gaps.
  70  *
  71  * All metadata io is in THIN_METADATA_BLOCK_SIZE sized/aligned chunks
  72  * from the block manager.
  73  *--------------------------------------------------------------------------*/
  74
  75 #define DM_MSG_PREFIX   "thin metadata"
  76
  77 #define THIN_SUPERBLOCK_MAGIC 27022010
  78 #define THIN_SUPERBLOCK_LOCATION 0
  79 #define THIN_VERSION 2
  80 #define SECTOR_TO_BLOCK_SHIFT 3
  81
  82 /*
  83  * For btree insert:
  84  *  3 for btree insert +
  85  *  2 for btree lookup used within space map
  86  * For btree remove:
  87  *  2 for shadow spine +
  88  *  4 for rebalance 3 child node
  89  */
  90 #define THIN_MAX_CONCURRENT_LOCKS 6
  91
  92 /* This should be plenty */
  93 #define SPACE_MAP_ROOT_SIZE 128
  94
  95 /*
  96  * Little endian on-disk superblock and device details.
  97  */
  98 struct thin_disk_superblock {
  99         __le32 csum;    /* Checksum of superblock except for this field. */
 100         __le32 flags;
 101         __le64 blocknr; /* This block number, dm_block_t. */
 102
 103         __u8 uuid[16];
 104         __le64 magic;
 105         __le32 version;
 106         __le32 time;
 107
 108         __le64 trans_id;
 109
 110         /*
 111          * Root held by userspace transactions.
 112          */
 113         __le64 held_root;
 114
 115         __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
 116         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 117
 118         /*
 119          * 2-level btree mapping (dev_id, (dev block, time)) -> data block
 120          */
 121         __le64 data_mapping_root;
 122
 123         /*
 124          * Device detail root mapping dev_id -> device_details
 125          */
 126         __le64 device_details_root;
 127
 128         __le32 data_block_size;         /* In 512-byte sectors. */
 129
 130         __le32 metadata_block_size;     /* In 512-byte sectors. */
 131         __le64 metadata_nr_blocks;
 132
 133         __le32 compat_flags;
 134         __le32 compat_ro_flags;
 135         __le32 incompat_flags;
 136 } __packed;
 137
 138 struct disk_device_details {
 139         __le64 mapped_blocks;
 140         __le64 transaction_id;          /* When created. */
 141         __le32 creation_time;
 142         __le32 snapshotted_time;
 143 } __packed;
 144
 145 struct dm_pool_metadata {
 146         struct hlist_node hash;
 147
 148         struct block_device *bdev;
 149         struct dm_block_manager *bm;
 150         struct dm_space_map *metadata_sm;
 151         struct dm_space_map *data_sm;
 152         struct dm_transaction_manager *tm;
 153         struct dm_transaction_manager *nb_tm;
 154
 155         /*
 156          * Two-level btree.
 157          * First level holds thin_dev_t.
 158          * Second level holds mappings.
 159          */
 160         struct dm_btree_info info;
 161
 162         /*
 163          * Non-blocking version of the above.
 164          */
 165         struct dm_btree_info nb_info;
 166
 167         /*
 168          * Just the top level for deleting whole devices.
 169          */
 170         struct dm_btree_info tl_info;
 171
 172         /*
 173          * Just the bottom level for creating new devices.
 174          */
 175         struct dm_btree_info bl_info;
 176
 177         /*
 178          * Describes the device details btree.
 179          */
 180         struct dm_btree_info details_info;
 181
 182         struct rw_semaphore root_lock;
 183         uint32_t time;
 184         dm_block_t root;
 185         dm_block_t details_root;
 186         struct list_head thin_devices;
 187         uint64_t trans_id;
 188         unsigned long flags;
 189         sector_t data_block_size;
 190
 191         /*
 192          * We reserve a section of the metadata for commit overhead.
 193          * All reported space does *not* include this.
 194          */
 195         dm_block_t metadata_reserve;
 196
 197         /*
 198          * Set if a transaction has to be aborted but the attempt to roll back
 199          * to the previous (good) transaction failed.  The only pool metadata
 200          * operation possible in this state is the closing of the device.
 201          */
 202         bool fail_io:1;
 203
 204         /*
 205          * Reading the space map roots can fail, so we read it into these
 206          * buffers before the superblock is locked and updated.
 207          */
 208         __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
 209         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 210 };
 211
 212 struct dm_thin_device {
 213         struct list_head list;
 214         struct dm_pool_metadata *pmd;
 215         dm_thin_id id;
 216
 217         int open_count;
 218         bool changed:1;
 219         bool aborted_with_changes:1;
 220         uint64_t mapped_blocks;
 221         uint64_t transaction_id;
 222         uint32_t creation_time;
 223         uint32_t snapshotted_time;
 224 };
 225
 226 /*----------------------------------------------------------------
 227  * superblock validator
 228  *--------------------------------------------------------------*/
 229
 230 #define SUPERBLOCK_CSUM_XOR 160774
 231
 232 static void sb_prepare_for_write(struct dm_block_validator *v,
 233                                  struct dm_block *b,
 234                                  size_t block_size)
 235 {
 236         struct thin_disk_superblock *disk_super = dm_block_data(b);
 237
 238         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 239         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 240                                                       block_size - sizeof(__le32),
 241                                                       SUPERBLOCK_CSUM_XOR));
 242 }
 243
 244 static int sb_check(struct dm_block_validator *v,
 245                     struct dm_block *b,
 246                     size_t block_size)
 247 {
 248         struct thin_disk_superblock *disk_super = dm_block_data(b);
 249         __le32 csum_le;
 250
 251         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 252                 DMERR("sb_check failed: blocknr %llu: "
 253                       "wanted %llu", le64_to_cpu(disk_super->blocknr),
 254                       (unsigned long long)dm_block_location(b));
 255                 return -ENOTBLK;
 256         }
 257
 258         if (le64_to_cpu(disk_super->magic) != THIN_SUPERBLOCK_MAGIC) {
 259                 DMERR("sb_check failed: magic %llu: "
 260                       "wanted %llu", le64_to_cpu(disk_super->magic),
 261                       (unsigned long long)THIN_SUPERBLOCK_MAGIC);
 262                 return -EILSEQ;
 263         }
 264
 265         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 266                                              block_size - sizeof(__le32),
 267                                              SUPERBLOCK_CSUM_XOR));
 268         if (csum_le != disk_super->csum) {
 269                 DMERR("sb_check failed: csum %u: wanted %u",
 270                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 271                 return -EILSEQ;
 272         }
 273
 274         return 0;
 275 }
 276
 277 static struct dm_block_validator sb_validator = {
 278         .name = "superblock",
 279         .prepare_for_write = sb_prepare_for_write,
 280         .check = sb_check
 281 };
 282
 283 /*----------------------------------------------------------------
 284  * Methods for the btree value types
 285  *--------------------------------------------------------------*/
 286
 287 static uint64_t pack_block_time(dm_block_t b, uint32_t t)
 288 {
 289         return (b << 24) | t;
 290 }
 291
 292 static void unpack_block_time(uint64_t v, dm_block_t *b, uint32_t *t)
 293 {
 294         *b = v >> 24;
 295         *t = v & ((1 << 24) - 1);
 296 }
 297
 298 static void data_block_inc(void *context, const void *value_le)
 299 {
 300         struct dm_space_map *sm = context;
 301         __le64 v_le;
 302         uint64_t b;
 303         uint32_t t;
 304
 305         memcpy(&v_le, value_le, sizeof(v_le));
 306         unpack_block_time(le64_to_cpu(v_le), &b, &t);
 307         dm_sm_inc_block(sm, b);
 308 }
 309
 310 static void data_block_dec(void *context, const void *value_le)
 311 {
 312         struct dm_space_map *sm = context;
 313         __le64 v_le;
 314         uint64_t b;
 315         uint32_t t;
 316
 317         memcpy(&v_le, value_le, sizeof(v_le));
 318         unpack_block_time(le64_to_cpu(v_le), &b, &t);
 319         dm_sm_dec_block(sm, b);
 320 }
 321
 322 static int data_block_equal(void *context, const void *value1_le, const void *value2_le)
 323 {
 324         __le64 v1_le, v2_le;
 325         uint64_t b1, b2;
 326         uint32_t t;
 327
 328         memcpy(&v1_le, value1_le, sizeof(v1_le));
 329         memcpy(&v2_le, value2_le, sizeof(v2_le));
 330         unpack_block_time(le64_to_cpu(v1_le), &b1, &t);
 331         unpack_block_time(le64_to_cpu(v2_le), &b2, &t);
 332
 333         return b1 == b2;
 334 }
 335
 336 static void subtree_inc(void *context, const void *value)
 337 {
 338         struct dm_btree_info *info = context;
 339         __le64 root_le;
 340         uint64_t root;
 341
 342         memcpy(&root_le, value, sizeof(root_le));
 343         root = le64_to_cpu(root_le);
 344         dm_tm_inc(info->tm, root);
 345 }
 346
 347 static void subtree_dec(void *context, const void *value)
 348 {
 349         struct dm_btree_info *info = context;
 350         __le64 root_le;
 351         uint64_t root;
 352
 353         memcpy(&root_le, value, sizeof(root_le));
 354         root = le64_to_cpu(root_le);
 355         if (dm_btree_del(info, root))
 356                 DMERR("btree delete failed");
 357 }
 358
 359 static int subtree_equal(void *context, const void *value1_le, const void *value2_le)
 360 {
 361         __le64 v1_le, v2_le;
 362         memcpy(&v1_le, value1_le, sizeof(v1_le));
 363         memcpy(&v2_le, value2_le, sizeof(v2_le));
 364
 365         return v1_le == v2_le;
 366 }
 367
 368 /*----------------------------------------------------------------*/
 369
 370 static int superblock_lock_zero(struct dm_pool_metadata *pmd,
 371                                 struct dm_block **sblock)
 372 {
 373         return dm_bm_write_lock_zero(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 374                                      &sb_validator, sblock);
 375 }
 376
 377 static int superblock_lock(struct dm_pool_metadata *pmd,
 378                            struct dm_block **sblock)
 379 {
 380         return dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 381                                 &sb_validator, sblock);
 382 }
 383
 384 static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
 385 {
 386         int r;
 387         unsigned i;
 388         struct dm_block *b;
 389         __le64 *data_le, zero = cpu_to_le64(0);
 390         unsigned block_size = dm_bm_block_size(bm) / sizeof(__le64);
 391
 392         /*
 393          * We can't use a validator here - it may be all zeroes.
 394          */
 395         r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, NULL, &b);
 396         if (r)
 397                 return r;
 398
 399         data_le = dm_block_data(b);
 400         *result = 1;
 401         for (i = 0; i < block_size; i++) {
 402                 if (data_le[i] != zero) {
 403                         *result = 0;
 404                         break;
 405                 }
 406         }
 407
 408         dm_bm_unlock(b);
 409
 410         return 0;
 411 }
 412
 413 static void __setup_btree_details(struct dm_pool_metadata *pmd)
 414 {
 415         pmd->info.tm = pmd->tm;
 416         pmd->info.levels = 2;
 417         pmd->info.value_type.context = pmd->data_sm;
 418         pmd->info.value_type.size = sizeof(__le64);
 419         pmd->info.value_type.inc = data_block_inc;
 420         pmd->info.value_type.dec = data_block_dec;
 421         pmd->info.value_type.equal = data_block_equal;
 422
 423         memcpy(&pmd->nb_info, &pmd->info, sizeof(pmd->nb_info));
 424         pmd->nb_info.tm = pmd->nb_tm;
 425
 426         pmd->tl_info.tm = pmd->tm;
 427         pmd->tl_info.levels = 1;
 428         pmd->tl_info.value_type.context = &pmd->bl_info;
 429         pmd->tl_info.value_type.size = sizeof(__le64);
 430         pmd->tl_info.value_type.inc = subtree_inc;
 431         pmd->tl_info.value_type.dec = subtree_dec;
 432         pmd->tl_info.value_type.equal = subtree_equal;
 433
 434         pmd->bl_info.tm = pmd->tm;
 435         pmd->bl_info.levels = 1;
 436         pmd->bl_info.value_type.context = pmd->data_sm;
 437         pmd->bl_info.value_type.size = sizeof(__le64);
 438         pmd->bl_info.value_type.inc = data_block_inc;
 439         pmd->bl_info.value_type.dec = data_block_dec;
 440         pmd->bl_info.value_type.equal = data_block_equal;
 441
 442         pmd->details_info.tm = pmd->tm;
 443         pmd->details_info.levels = 1;
 444         pmd->details_info.value_type.context = NULL;
 445         pmd->details_info.value_type.size = sizeof(struct disk_device_details);
 446         pmd->details_info.value_type.inc = NULL;
 447         pmd->details_info.value_type.dec = NULL;
 448         pmd->details_info.value_type.equal = NULL;
 449 }
 450
 451 static int save_sm_roots(struct dm_pool_metadata *pmd)
 452 {
 453         int r;
 454         size_t len;
 455
 456         r = dm_sm_root_size(pmd->metadata_sm, &len);
 457         if (r < 0)
 458                 return r;
 459
 460         r = dm_sm_copy_root(pmd->metadata_sm, &pmd->metadata_space_map_root, len);
 461         if (r < 0)
 462                 return r;
 463
 464         r = dm_sm_root_size(pmd->data_sm, &len);
 465         if (r < 0)
 466                 return r;
 467
 468         return dm_sm_copy_root(pmd->data_sm, &pmd->data_space_map_root, len);
 469 }
 470
 471 static void copy_sm_roots(struct dm_pool_metadata *pmd,
 472                           struct thin_disk_superblock *disk)
 473 {
 474         memcpy(&disk->metadata_space_map_root,
 475                &pmd->metadata_space_map_root,
 476                sizeof(pmd->metadata_space_map_root));
 477
 478         memcpy(&disk->data_space_map_root,
 479                &pmd->data_space_map_root,
 480                sizeof(pmd->data_space_map_root));
 481 }
 482
 483 static int __write_initial_superblock(struct dm_pool_metadata *pmd)
 484 {
 485         int r;
 486         struct dm_block *sblock;
 487         struct thin_disk_superblock *disk_super;
 488         sector_t bdev_size = i_size_read(pmd->bdev->bd_inode) >> SECTOR_SHIFT;
 489
 490         if (bdev_size > THIN_METADATA_MAX_SECTORS)
 491                 bdev_size = THIN_METADATA_MAX_SECTORS;
 492
 493         r = dm_sm_commit(pmd->data_sm);
 494         if (r < 0)
 495                 return r;
 496
 497         r = dm_tm_pre_commit(pmd->tm);
 498         if (r < 0)
 499                 return r;
 500
 501         r = save_sm_roots(pmd);
 502         if (r < 0)
 503                 return r;
 504
 505         r = superblock_lock_zero(pmd, &sblock);
 506         if (r)
 507                 return r;
 508
 509         disk_super = dm_block_data(sblock);
 510         disk_super->flags = 0;
 511         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 512         disk_super->magic = cpu_to_le64(THIN_SUPERBLOCK_MAGIC);
 513         disk_super->version = cpu_to_le32(THIN_VERSION);
 514         disk_super->time = 0;
 515         disk_super->trans_id = 0;
 516         disk_super->held_root = 0;
 517
 518         copy_sm_roots(pmd, disk_super);
 519
 520         disk_super->data_mapping_root = cpu_to_le64(pmd->root);
 521         disk_super->device_details_root = cpu_to_le64(pmd->details_root);
 522         disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
 523         disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
 524         disk_super->data_block_size = cpu_to_le32(pmd->data_block_size);
 525
 526         return dm_tm_commit(pmd->tm, sblock);
 527 }
 528
 529 static int __format_metadata(struct dm_pool_metadata *pmd)
 530 {
 531         int r;
 532
 533         r = dm_tm_create_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 534                                  &pmd->tm, &pmd->metadata_sm);
 535         if (r < 0) {
 536                 DMERR("tm_create_with_sm failed");
 537                 return r;
 538         }
 539
 540         pmd->data_sm = dm_sm_disk_create(pmd->tm, 0);
 541         if (IS_ERR(pmd->data_sm)) {
 542                 DMERR("sm_disk_create failed");
 543                 r = PTR_ERR(pmd->data_sm);
 544                 goto bad_cleanup_tm;
 545         }
 546
 547         pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
 548         if (!pmd->nb_tm) {
 549                 DMERR("could not create non-blocking clone tm");
 550                 r = -ENOMEM;
 551                 goto bad_cleanup_data_sm;
 552         }
 553
 554         __setup_btree_details(pmd);
 555
 556         r = dm_btree_empty(&pmd->info, &pmd->root);
 557         if (r < 0)
 558                 goto bad_cleanup_nb_tm;
 559
 560         r = dm_btree_empty(&pmd->details_info, &pmd->details_root);
 561         if (r < 0) {
 562                 DMERR("couldn't create devices root");
 563                 goto bad_cleanup_nb_tm;
 564         }
 565
 566         r = __write_initial_superblock(pmd);
 567         if (r)
 568                 goto bad_cleanup_nb_tm;
 569
 570         return 0;
 571
 572 bad_cleanup_nb_tm:
 573         dm_tm_destroy(pmd->nb_tm);
 574 bad_cleanup_data_sm:
 575         dm_sm_destroy(pmd->data_sm);
 576 bad_cleanup_tm:
 577         dm_tm_destroy(pmd->tm);
 578         dm_sm_destroy(pmd->metadata_sm);
 579
 580         return r;
 581 }
 582
 583 static int __check_incompat_features(struct thin_disk_superblock *disk_super,
 584                                      struct dm_pool_metadata *pmd)
 585 {
 586         uint32_t features;
 587
 588         features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
 589         if (features) {
 590                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 591                       (unsigned long)features);
 592                 return -EINVAL;
 593         }
 594
 595         /*
 596          * Check for read-only metadata to skip the following RDWR checks.
 597          */
 598         if (get_disk_ro(pmd->bdev->bd_disk))
 599                 return 0;
 600
 601         features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
 602         if (features) {
 603                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 604                       (unsigned long)features);
 605                 return -EINVAL;
 606         }
 607
 608         return 0;
 609 }
 610
 611 static int __open_metadata(struct dm_pool_metadata *pmd)
 612 {
 613         int r;
 614         struct dm_block *sblock;
 615         struct thin_disk_superblock *disk_super;
 616
 617         r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 618                             &sb_validator, &sblock);
 619         if (r < 0) {
 620                 DMERR("couldn't read superblock");
 621                 return r;
 622         }
 623
 624         disk_super = dm_block_data(sblock);
 625
 626         /* Verify the data block size hasn't changed */
 627         if (le32_to_cpu(disk_super->data_block_size) != pmd->data_block_size) {
 628                 DMERR("changing the data block size (from %u to %llu) is not supported",
 629                       le32_to_cpu(disk_super->data_block_size),
 630                       (unsigned long long)pmd->data_block_size);
 631                 r = -EINVAL;
 632                 goto bad_unlock_sblock;
 633         }
 634
 635         r = __check_incompat_features(disk_super, pmd);
 636         if (r < 0)
 637                 goto bad_unlock_sblock;
 638
 639         r = dm_tm_open_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 640                                disk_super->metadata_space_map_root,
 641                                sizeof(disk_super->metadata_space_map_root),
 642                                &pmd->tm, &pmd->metadata_sm);
 643         if (r < 0) {
 644                 DMERR("tm_open_with_sm failed");
 645                 goto bad_unlock_sblock;
 646         }
 647
 648         pmd->data_sm = dm_sm_disk_open(pmd->tm, disk_super->data_space_map_root,
 649                                        sizeof(disk_super->data_space_map_root));
 650         if (IS_ERR(pmd->data_sm)) {
 651                 DMERR("sm_disk_open failed");
 652                 r = PTR_ERR(pmd->data_sm);
 653                 goto bad_cleanup_tm;
 654         }
 655
 656         pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
 657         if (!pmd->nb_tm) {
 658                 DMERR("could not create non-blocking clone tm");
 659                 r = -ENOMEM;
 660                 goto bad_cleanup_data_sm;
 661         }
 662
 663         __setup_btree_details(pmd);
 664         dm_bm_unlock(sblock);
 665
 666         return 0;
 667
 668 bad_cleanup_data_sm:
 669         dm_sm_destroy(pmd->data_sm);
 670 bad_cleanup_tm:
 671         dm_tm_destroy(pmd->tm);
 672         dm_sm_destroy(pmd->metadata_sm);
 673 bad_unlock_sblock:
 674         dm_bm_unlock(sblock);
 675
 676         return r;
 677 }
 678
 679 static int __open_or_format_metadata(struct dm_pool_metadata *pmd, bool format_device)
 680 {
 681         int r, unformatted;
 682
 683         r = __superblock_all_zeroes(pmd->bm, &unformatted);
 684         if (r)
 685                 return r;
 686
 687         if (unformatted)
 688                 return format_device ? __format_metadata(pmd) : -EPERM;
 689
 690         return __open_metadata(pmd);
 691 }
 692
 693 static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool format_device)
 694 {
 695         int r;
 696
 697         pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 698                                           THIN_MAX_CONCURRENT_LOCKS);
 699         if (IS_ERR(pmd->bm)) {
 700                 DMERR("could not create block manager");
 701                 return PTR_ERR(pmd->bm);
 702         }
 703
 704         r = __open_or_format_metadata(pmd, format_device);
 705         if (r)
 706                 dm_block_manager_destroy(pmd->bm);
 707
 708         return r;
 709 }
 710
 711 static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd)
 712 {
 713         dm_sm_destroy(pmd->data_sm);
 714         dm_sm_destroy(pmd->metadata_sm);
 715         dm_tm_destroy(pmd->nb_tm);
 716         dm_tm_destroy(pmd->tm);
 717         dm_block_manager_destroy(pmd->bm);
 718 }
 719
 720 static int __begin_transaction(struct dm_pool_metadata *pmd)
 721 {
 722         int r;
 723         struct thin_disk_superblock *disk_super;
 724         struct dm_block *sblock;
 725
 726         /*
 727          * We re-read the superblock every time.  Shouldn't need to do this
 728          * really.
 729          */
 730         r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 731                             &sb_validator, &sblock);
 732         if (r)
 733                 return r;
 734
 735         disk_super = dm_block_data(sblock);
 736         pmd->time = le32_to_cpu(disk_super->time);
 737         pmd->root = le64_to_cpu(disk_super->data_mapping_root);
 738         pmd->details_root = le64_to_cpu(disk_super->device_details_root);
 739         pmd->trans_id = le64_to_cpu(disk_super->trans_id);
 740         pmd->flags = le32_to_cpu(disk_super->flags);
 741         pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 742
 743         dm_bm_unlock(sblock);
 744         return 0;
 745 }
 746
 747 static int __write_changed_details(struct dm_pool_metadata *pmd)
 748 {
 749         int r;
 750         struct dm_thin_device *td, *tmp;
 751         struct disk_device_details details;
 752         uint64_t key;
 753
 754         list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
 755                 if (!td->changed)
 756                         continue;
 757
 758                 key = td->id;
 759
 760                 details.mapped_blocks = cpu_to_le64(td->mapped_blocks);
 761                 details.transaction_id = cpu_to_le64(td->transaction_id);
 762                 details.creation_time = cpu_to_le32(td->creation_time);
 763                 details.snapshotted_time = cpu_to_le32(td->snapshotted_time);
 764                 __dm_bless_for_disk(&details);
 765
 766                 r = dm_btree_insert(&pmd->details_info, pmd->details_root,
 767                                     &key, &details, &pmd->details_root);
 768                 if (r)
 769                         return r;
 770
 771                 if (td->open_count)
 772                         td->changed = 0;
 773                 else {
 774                         list_del(&td->list);
 775                         kfree(td);
 776                 }
 777         }
 778
 779         return 0;
 780 }
 781
 782 static int __commit_transaction(struct dm_pool_metadata *pmd)
 783 {
 784         int r;
 785         struct thin_disk_superblock *disk_super;
 786         struct dm_block *sblock;
 787
 788         /*
 789          * We need to know if the thin_disk_superblock exceeds a 512-byte sector.
 790          */
 791         BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
 792
 793         r = __write_changed_details(pmd);
 794         if (r < 0)
 795                 return r;
 796
 797         r = dm_sm_commit(pmd->data_sm);
 798         if (r < 0)
 799                 return r;
 800
 801         r = dm_tm_pre_commit(pmd->tm);
 802         if (r < 0)
 803                 return r;
 804
 805         r = save_sm_roots(pmd);
 806         if (r < 0)
 807                 return r;
 808
 809         r = superblock_lock(pmd, &sblock);
 810         if (r)
 811                 return r;
 812
 813         disk_super = dm_block_data(sblock);
 814         disk_super->time = cpu_to_le32(pmd->time);
 815         disk_super->data_mapping_root = cpu_to_le64(pmd->root);
 816         disk_super->device_details_root = cpu_to_le64(pmd->details_root);
 817         disk_super->trans_id = cpu_to_le64(pmd->trans_id);
 818         disk_super->flags = cpu_to_le32(pmd->flags);
 819
 820         copy_sm_roots(pmd, disk_super);
 821
 822         return dm_tm_commit(pmd->tm, sblock);
 823 }
 824
 825 static void __set_metadata_reserve(struct dm_pool_metadata *pmd)
 826 {
 827         int r;
 828         dm_block_t total;
 829         dm_block_t max_blocks = 4096; /* 16M */
 830
 831         r = dm_sm_get_nr_blocks(pmd->metadata_sm, &total);
 832         if (r) {
 833                 DMERR("could not get size of metadata device");
 834                 pmd->metadata_reserve = max_blocks;
 835         } else
 836                 pmd->metadata_reserve = min(max_blocks, div_u64(total, 10));
 837 }
 838
 839 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
 840                                                sector_t data_block_size,
 841                                                bool format_device)
 842 {
 843         int r;
 844         struct dm_pool_metadata *pmd;
 845
 846         pmd = kmalloc(sizeof(*pmd), GFP_KERNEL);
 847         if (!pmd) {
 848                 DMERR("could not allocate metadata struct");
 849                 return ERR_PTR(-ENOMEM);
 850         }
 851
 852         init_rwsem(&pmd->root_lock);
 853         pmd->time = 0;
 854         INIT_LIST_HEAD(&pmd->thin_devices);
 855         pmd->fail_io = false;
 856         pmd->bdev = bdev;
 857         pmd->data_block_size = data_block_size;
 858
 859         r = __create_persistent_data_objects(pmd, format_device);
 860         if (r) {
 861                 kfree(pmd);
 862                 return ERR_PTR(r);
 863         }
 864
 865         r = __begin_transaction(pmd);
 866         if (r < 0) {
 867                 if (dm_pool_metadata_close(pmd) < 0)
 868                         DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
 869                 return ERR_PTR(r);
 870         }
 871
 872         __set_metadata_reserve(pmd);
 873
 874         return pmd;
 875 }
 876
 877 int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
 878 {
 879         int r;
 880         unsigned open_devices = 0;
 881         struct dm_thin_device *td, *tmp;
 882
 883         down_read(&pmd->root_lock);
 884         list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
 885                 if (td->open_count)
 886                         open_devices++;
 887                 else {
 888                         list_del(&td->list);
 889                         kfree(td);
 890                 }
 891         }
 892         up_read(&pmd->root_lock);
 893
 894         if (open_devices) {
 895                 DMERR("attempt to close pmd when %u device(s) are still open",
 896                        open_devices);
 897                 return -EBUSY;
 898         }
 899
 900         if (!dm_bm_is_read_only(pmd->bm) && !pmd->fail_io) {
 901                 r = __commit_transaction(pmd);
 902                 if (r < 0)
 903                         DMWARN("%s: __commit_transaction() failed, error = %d",
 904                                __func__, r);
 905         }
 906
 907         if (!pmd->fail_io)
 908                 __destroy_persistent_data_objects(pmd);
 909
 910         kfree(pmd);
 911         return 0;
 912 }
 913
 914 /*
 915  * __open_device: Returns @td corresponding to device with id @dev,
 916  * creating it if @create is set and incrementing @td->open_count.
 917  * On failure, @td is undefined.
 918  */
 919 static int __open_device(struct dm_pool_metadata *pmd,
 920                          dm_thin_id dev, int create,
 921                          struct dm_thin_device **td)
 922 {
 923         int r, changed = 0;
 924         struct dm_thin_device *td2;
 925         uint64_t key = dev;
 926         struct disk_device_details details_le;
 927
 928         /*
 929          * If the device is already open, return it.
 930          */
 931         list_for_each_entry(td2, &pmd->thin_devices, list)
 932                 if (td2->id == dev) {
 933                         /*
 934                          * May not create an already-open device.
 935                          */
 936                         if (create)
 937                                 return -EEXIST;
 938
 939                         td2->open_count++;
 940                         *td = td2;
 941                         return 0;
 942                 }
 943
 944         /*
 945          * Check the device exists.
 946          */
 947         r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
 948                             &key, &details_le);
 949         if (r) {
 950                 if (r != -ENODATA || !create)
 951                         return r;
 952
 953                 /*
 954                  * Create new device.
 955                  */
 956                 changed = 1;
 957                 details_le.mapped_blocks = 0;
 958                 details_le.transaction_id = cpu_to_le64(pmd->trans_id);
 959                 details_le.creation_time = cpu_to_le32(pmd->time);
 960                 details_le.snapshotted_time = cpu_to_le32(pmd->time);
 961         }
 962
 963         *td = kmalloc(sizeof(**td), GFP_NOIO);
 964         if (!*td)
 965                 return -ENOMEM;
 966
 967         (*td)->pmd = pmd;
 968         (*td)->id = dev;
 969         (*td)->open_count = 1;
 970         (*td)->changed = changed;
 971         (*td)->aborted_with_changes = false;
 972         (*td)->mapped_blocks = le64_to_cpu(details_le.mapped_blocks);
 973         (*td)->transaction_id = le64_to_cpu(details_le.transaction_id);
 974         (*td)->creation_time = le32_to_cpu(details_le.creation_time);
 975         (*td)->snapshotted_time = le32_to_cpu(details_le.snapshotted_time);
 976
 977         list_add(&(*td)->list, &pmd->thin_devices);
 978
 979         return 0;
 980 }
 981
 982 static void __close_device(struct dm_thin_device *td)
 983 {
 984         --td->open_count;
 985 }
 986
 987 static int __create_thin(struct dm_pool_metadata *pmd,
 988                          dm_thin_id dev)
 989 {
 990         int r;
 991         dm_block_t dev_root;
 992         uint64_t key = dev;
 993         struct disk_device_details details_le;
 994         struct dm_thin_device *td;
 995         __le64 value;
 996
 997         r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
 998                             &key, &details_le);
 999         if (!r)
1000                 return -EEXIST;
1001
1002         /*
1003          * Create an empty btree for the mappings.
1004          */
1005         r = dm_btree_empty(&pmd->bl_info, &dev_root);
1006         if (r)
1007                 return r;
1008
1009         /*
1010          * Insert it into the main mapping tree.
1011          */
1012         value = cpu_to_le64(dev_root);
1013         __dm_bless_for_disk(&value);
1014         r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
1015         if (r) {
1016                 dm_btree_del(&pmd->bl_info, dev_root);
1017                 return r;
1018         }
1019
1020         r = __open_device(pmd, dev, 1, &td);
1021         if (r) {
1022                 dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1023                 dm_btree_del(&pmd->bl_info, dev_root);
1024                 return r;
1025         }
1026         __close_device(td);
1027
1028         return r;
1029 }
1030
1031 int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev)
1032 {
1033         int r = -EINVAL;
1034
1035         down_write(&pmd->root_lock);
1036         if (!pmd->fail_io)
1037                 r = __create_thin(pmd, dev);
1038         up_write(&pmd->root_lock);
1039
1040         return r;
1041 }
1042
1043 static int __set_snapshot_details(struct dm_pool_metadata *pmd,
1044                                   struct dm_thin_device *snap,
1045                                   dm_thin_id origin, uint32_t time)
1046 {
1047         int r;
1048         struct dm_thin_device *td;
1049
1050         r = __open_device(pmd, origin, 0, &td);
1051         if (r)
1052                 return r;
1053
1054         td->changed = 1;
1055         td->snapshotted_time = time;
1056
1057         snap->mapped_blocks = td->mapped_blocks;
1058         snap->snapshotted_time = time;
1059         __close_device(td);
1060
1061         return 0;
1062 }
1063
1064 static int __create_snap(struct dm_pool_metadata *pmd,
1065                          dm_thin_id dev, dm_thin_id origin)
1066 {
1067         int r;
1068         dm_block_t origin_root;
1069         uint64_t key = origin, dev_key = dev;
1070         struct dm_thin_device *td;
1071         struct disk_device_details details_le;
1072         __le64 value;
1073
1074         /* check this device is unused */
1075         r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
1076                             &dev_key, &details_le);
1077         if (!r)
1078                 return -EEXIST;
1079
1080         /* find the mapping tree for the origin */
1081         r = dm_btree_lookup(&pmd->tl_info, pmd->root, &key, &value);
1082         if (r)
1083                 return r;
1084         origin_root = le64_to_cpu(value);
1085
1086         /* clone the origin, an inc will do */
1087         dm_tm_inc(pmd->tm, origin_root);
1088
1089         /* insert into the main mapping tree */
1090         value = cpu_to_le64(origin_root);
1091         __dm_bless_for_disk(&value);
1092         key = dev;
1093         r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
1094         if (r) {
1095                 dm_tm_dec(pmd->tm, origin_root);
1096                 return r;
1097         }
1098
1099         pmd->time++;
1100
1101         r = __open_device(pmd, dev, 1, &td);
1102         if (r)
1103                 goto bad;
1104
1105         r = __set_snapshot_details(pmd, td, origin, pmd->time);
1106         __close_device(td);
1107
1108         if (r)
1109                 goto bad;
1110
1111         return 0;
1112
1113 bad:
1114         dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1115         dm_btree_remove(&pmd->details_info, pmd->details_root,
1116                         &key, &pmd->details_root);
1117         return r;
1118 }
1119
1120 int dm_pool_create_snap(struct dm_pool_metadata *pmd,
1121                                  dm_thin_id dev,
1122                                  dm_thin_id origin)
1123 {
1124         int r = -EINVAL;
1125
1126         down_write(&pmd->root_lock);
1127         if (!pmd->fail_io)
1128                 r = __create_snap(pmd, dev, origin);
1129         up_write(&pmd->root_lock);
1130
1131         return r;
1132 }
1133
1134 static int __delete_device(struct dm_pool_metadata *pmd, dm_thin_id dev)
1135 {
1136         int r;
1137         uint64_t key = dev;
1138         struct dm_thin_device *td;
1139
1140         /* TODO: failure should mark the transaction invalid */
1141         r = __open_device(pmd, dev, 0, &td);
1142         if (r)
1143                 return r;
1144
1145         if (td->open_count > 1) {
1146                 __close_device(td);
1147                 return -EBUSY;
1148         }
1149
1150         list_del(&td->list);
1151         kfree(td);
1152         r = dm_btree_remove(&pmd->details_info, pmd->details_root,
1153                             &key, &pmd->details_root);
1154         if (r)
1155                 return r;
1156
1157         r = dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1158         if (r)
1159                 return r;
1160
1161         return 0;
1162 }
1163
1164 int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
1165                                dm_thin_id dev)
1166 {
1167         int r = -EINVAL;
1168
1169         down_write(&pmd->root_lock);
1170         if (!pmd->fail_io)
1171                 r = __delete_device(pmd, dev);
1172         up_write(&pmd->root_lock);
1173
1174         return r;
1175 }
1176
1177 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
1178                                         uint64_t current_id,
1179                                         uint64_t new_id)
1180 {
1181         int r = -EINVAL;
1182
1183         down_write(&pmd->root_lock);
1184
1185         if (pmd->fail_io)
1186                 goto out;
1187
1188         if (pmd->trans_id != current_id) {
1189                 DMERR("mismatched transaction id");
1190                 goto out;
1191         }
1192
1193         pmd->trans_id = new_id;
1194         r = 0;
1195
1196 out:
1197         up_write(&pmd->root_lock);
1198
1199         return r;
1200 }
1201
1202 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
1203                                         uint64_t *result)
1204 {
1205         int r = -EINVAL;
1206
1207         down_read(&pmd->root_lock);
1208         if (!pmd->fail_io) {
1209                 *result = pmd->trans_id;
1210                 r = 0;
1211         }
1212         up_read(&pmd->root_lock);
1213
1214         return r;
1215 }
1216
1217 static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
1218 {
1219         int r, inc;
1220         struct thin_disk_superblock *disk_super;
1221         struct dm_block *copy, *sblock;
1222         dm_block_t held_root;
1223
1224         /*
1225          * We commit to ensure the btree roots which we increment in a
1226          * moment are up to date.
1227          */
1228         __commit_transaction(pmd);
1229
1230         /*
1231          * Copy the superblock.
1232          */
1233         dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
1234         r = dm_tm_shadow_block(pmd->tm, THIN_SUPERBLOCK_LOCATION,
1235                                &sb_validator, &copy, &inc);
1236         if (r)
1237                 return r;
1238
1239         BUG_ON(!inc);
1240
1241         held_root = dm_block_location(copy);
1242         disk_super = dm_block_data(copy);
1243
1244         if (le64_to_cpu(disk_super->held_root)) {
1245                 DMWARN("Pool metadata snapshot already exists: release this before taking another.");
1246
1247                 dm_tm_dec(pmd->tm, held_root);
1248                 dm_tm_unlock(pmd->tm, copy);
1249                 return -EBUSY;
1250         }
1251
1252         /*
1253          * Wipe the spacemap since we're not publishing this.
1254          */
1255         memset(&disk_super->data_space_map_root, 0,
1256                sizeof(disk_super->data_space_map_root));
1257         memset(&disk_super->metadata_space_map_root, 0,
1258                sizeof(disk_super->metadata_space_map_root));
1259
1260         /*
1261          * Increment the data structures that need to be preserved.
1262          */
1263         dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->data_mapping_root));
1264         dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->device_details_root));
1265         dm_tm_unlock(pmd->tm, copy);
1266
1267         /*
1268          * Write the held root into the superblock.
1269          */
1270         r = superblock_lock(pmd, &sblock);
1271         if (r) {
1272                 dm_tm_dec(pmd->tm, held_root);
1273                 return r;
1274         }
1275
1276         disk_super = dm_block_data(sblock);
1277         disk_super->held_root = cpu_to_le64(held_root);
1278         dm_bm_unlock(sblock);
1279         return 0;
1280 }
1281
1282 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd)
1283 {
1284         int r = -EINVAL;
1285
1286         down_write(&pmd->root_lock);
1287         if (!pmd->fail_io)
1288                 r = __reserve_metadata_snap(pmd);
1289         up_write(&pmd->root_lock);
1290
1291         return r;
1292 }
1293
1294 static int __release_metadata_snap(struct dm_pool_metadata *pmd)
1295 {
1296         int r;
1297         struct thin_disk_superblock *disk_super;
1298         struct dm_block *sblock, *copy;
1299         dm_block_t held_root;
1300
1301         r = superblock_lock(pmd, &sblock);
1302         if (r)
1303                 return r;
1304
1305         disk_super = dm_block_data(sblock);
1306         held_root = le64_to_cpu(disk_super->held_root);
1307         disk_super->held_root = cpu_to_le64(0);
1308
1309         dm_bm_unlock(sblock);
1310
1311         if (!held_root) {
1312                 DMWARN("No pool metadata snapshot found: nothing to release.");
1313                 return -EINVAL;
1314         }
1315
1316         r = dm_tm_read_lock(pmd->tm, held_root, &sb_validator, &copy);
1317         if (r)
1318                 return r;
1319
1320         disk_super = dm_block_data(copy);
1321         dm_btree_del(&pmd->info, le64_to_cpu(disk_super->data_mapping_root));
1322         dm_btree_del(&pmd->details_info, le64_to_cpu(disk_super->device_details_root));
1323         dm_sm_dec_block(pmd->metadata_sm, held_root);
1324
1325         dm_tm_unlock(pmd->tm, copy);
1326
1327         return 0;
1328 }
1329
1330 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd)
1331 {
1332         int r = -EINVAL;
1333
1334         down_write(&pmd->root_lock);
1335         if (!pmd->fail_io)
1336                 r = __release_metadata_snap(pmd);
1337         up_write(&pmd->root_lock);
1338
1339         return r;
1340 }
1341
1342 static int __get_metadata_snap(struct dm_pool_metadata *pmd,
1343                                dm_block_t *result)
1344 {
1345         int r;
1346         struct thin_disk_superblock *disk_super;
1347         struct dm_block *sblock;
1348
1349         r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
1350                             &sb_validator, &sblock);
1351         if (r)
1352                 return r;
1353
1354         disk_super = dm_block_data(sblock);
1355         *result = le64_to_cpu(disk_super->held_root);
1356
1357         dm_bm_unlock(sblock);
1358
1359         return 0;
1360 }
1361
1362 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
1363                               dm_block_t *result)
1364 {
1365         int r = -EINVAL;
1366
1367         down_read(&pmd->root_lock);
1368         if (!pmd->fail_io)
1369                 r = __get_metadata_snap(pmd, result);
1370         up_read(&pmd->root_lock);
1371
1372         return r;
1373 }
1374
1375 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
1376                              struct dm_thin_device **td)
1377 {
1378         int r = -EINVAL;
1379
1380         down_write(&pmd->root_lock);
1381         if (!pmd->fail_io)
1382                 r = __open_device(pmd, dev, 0, td);
1383         up_write(&pmd->root_lock);
1384
1385         return r;
1386 }
1387
1388 int dm_pool_close_thin_device(struct dm_thin_device *td)
1389 {
1390         down_write(&td->pmd->root_lock);
1391         __close_device(td);
1392         up_write(&td->pmd->root_lock);
1393
1394         return 0;
1395 }
1396
1397 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td)
1398 {
1399         return td->id;
1400 }
1401
1402 /*
1403  * Check whether @time (of block creation) is older than @td's last snapshot.
1404  * If so then the associated block is shared with the last snapshot device.
1405  * Any block on a device created *after* the device last got snapshotted is
1406  * necessarily not shared.
1407  */
1408 static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
1409 {
1410         return td->snapshotted_time > time;
1411 }
1412
1413 static void unpack_lookup_result(struct dm_thin_device *td, __le64 value,
1414                                  struct dm_thin_lookup_result *result)
1415 {
1416         uint64_t block_time = 0;
1417         dm_block_t exception_block;
1418         uint32_t exception_time;
1419
1420         block_time = le64_to_cpu(value);
1421         unpack_block_time(block_time, &exception_block, &exception_time);
1422         result->block = exception_block;
1423         result->shared = __snapshotted_since(td, exception_time);
1424 }
1425
1426 static int __find_block(struct dm_thin_device *td, dm_block_t block,
1427                         int can_issue_io, struct dm_thin_lookup_result *result)
1428 {
1429         int r;
1430         __le64 value;
1431         struct dm_pool_metadata *pmd = td->pmd;
1432         dm_block_t keys[2] = { td->id, block };
1433         struct dm_btree_info *info;
1434
1435         if (can_issue_io) {
1436                 info = &pmd->info;
1437         } else
1438                 info = &pmd->nb_info;
1439
1440         r = dm_btree_lookup(info, pmd->root, keys, &value);
1441         if (!r)
1442                 unpack_lookup_result(td, value, result);
1443
1444         return r;
1445 }
1446
1447 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
1448                        int can_issue_io, struct dm_thin_lookup_result *result)
1449 {
1450         int r;
1451         struct dm_pool_metadata *pmd = td->pmd;
1452
1453         down_read(&pmd->root_lock);
1454         if (pmd->fail_io) {
1455                 up_read(&pmd->root_lock);
1456                 return -EINVAL;
1457         }
1458
1459         r = __find_block(td, block, can_issue_io, result);
1460
1461         up_read(&pmd->root_lock);
1462         return r;
1463 }
1464
1465 static int __find_next_mapped_block(struct dm_thin_device *td, dm_block_t block,
1466                                           dm_block_t *vblock,
1467                                           struct dm_thin_lookup_result *result)
1468 {
1469         int r;
1470         __le64 value;
1471         struct dm_pool_metadata *pmd = td->pmd;
1472         dm_block_t keys[2] = { td->id, block };
1473
1474         r = dm_btree_lookup_next(&pmd->info, pmd->root, keys, vblock, &value);
1475         if (!r)
1476                 unpack_lookup_result(td, value, result);
1477
1478         return r;
1479 }
1480
1481 static int __find_mapped_range(struct dm_thin_device *td,
1482                                dm_block_t begin, dm_block_t end,
1483                                dm_block_t *thin_begin, dm_block_t *thin_end,
1484                                dm_block_t *pool_begin, bool *maybe_shared)
1485 {
1486         int r;
1487         dm_block_t pool_end;
1488         struct dm_thin_lookup_result lookup;
1489
1490         if (end < begin)
1491                 return -ENODATA;
1492
1493         r = __find_next_mapped_block(td, begin, &begin, &lookup);
1494         if (r)
1495                 return r;
1496
1497         if (begin >= end)
1498                 return -ENODATA;
1499
1500         *thin_begin = begin;
1501         *pool_begin = lookup.block;
1502         *maybe_shared = lookup.shared;
1503
1504         begin++;
1505         pool_end = *pool_begin + 1;
1506         while (begin != end) {
1507                 r = __find_block(td, begin, true, &lookup);
1508                 if (r) {
1509                         if (r == -ENODATA)
1510                                 break;
1511                         else
1512                                 return r;
1513                 }
1514
1515                 if ((lookup.block != pool_end) ||
1516                     (lookup.shared != *maybe_shared))
1517                         break;
1518
1519                 pool_end++;
1520                 begin++;
1521         }
1522
1523         *thin_end = begin;
1524         return 0;
1525 }
1526
1527 int dm_thin_find_mapped_range(struct dm_thin_device *td,
1528                               dm_block_t begin, dm_block_t end,
1529                               dm_block_t *thin_begin, dm_block_t *thin_end,
1530                               dm_block_t *pool_begin, bool *maybe_shared)
1531 {
1532         int r = -EINVAL;
1533         struct dm_pool_metadata *pmd = td->pmd;
1534
1535         down_read(&pmd->root_lock);
1536         if (!pmd->fail_io) {
1537                 r = __find_mapped_range(td, begin, end, thin_begin, thin_end,
1538                                         pool_begin, maybe_shared);
1539         }
1540         up_read(&pmd->root_lock);
1541
1542         return r;
1543 }
1544
1545 static int __insert(struct dm_thin_device *td, dm_block_t block,
1546                     dm_block_t data_block)
1547 {
1548         int r, inserted;
1549         __le64 value;
1550         struct dm_pool_metadata *pmd = td->pmd;
1551         dm_block_t keys[2] = { td->id, block };
1552
1553         value = cpu_to_le64(pack_block_time(data_block, pmd->time));
1554         __dm_bless_for_disk(&value);
1555
1556         r = dm_btree_insert_notify(&pmd->info, pmd->root, keys, &value,
1557                                    &pmd->root, &inserted);
1558         if (r)
1559                 return r;
1560
1561         td->changed = 1;
1562         if (inserted)
1563                 td->mapped_blocks++;
1564
1565         return 0;
1566 }
1567
1568 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
1569                          dm_block_t data_block)
1570 {
1571         int r = -EINVAL;
1572
1573         down_write(&td->pmd->root_lock);
1574         if (!td->pmd->fail_io)
1575                 r = __insert(td, block, data_block);
1576         up_write(&td->pmd->root_lock);
1577
1578         return r;
1579 }
1580
1581 static int __remove(struct dm_thin_device *td, dm_block_t block)
1582 {
1583         int r;
1584         struct dm_pool_metadata *pmd = td->pmd;
1585         dm_block_t keys[2] = { td->id, block };
1586
1587         r = dm_btree_remove(&pmd->info, pmd->root, keys, &pmd->root);
1588         if (r)
1589                 return r;
1590
1591         td->mapped_blocks--;
1592         td->changed = 1;
1593
1594         return 0;
1595 }
1596
1597 static int __remove_range(struct dm_thin_device *td, dm_block_t begin, dm_block_t end)
1598 {
1599         int r;
1600         unsigned count, total_count = 0;
1601         struct dm_pool_metadata *pmd = td->pmd;
1602         dm_block_t keys[1] = { td->id };
1603         __le64 value;
1604         dm_block_t mapping_root;
1605
1606         /*
1607          * Find the mapping tree
1608          */
1609         r = dm_btree_lookup(&pmd->tl_info, pmd->root, keys, &value);
1610         if (r)
1611                 return r;
1612
1613         /*
1614          * Remove from the mapping tree, taking care to inc the
1615          * ref count so it doesn't get deleted.
1616          */
1617         mapping_root = le64_to_cpu(value);
1618         dm_tm_inc(pmd->tm, mapping_root);
1619         r = dm_btree_remove(&pmd->tl_info, pmd->root, keys, &pmd->root);
1620         if (r)
1621                 return r;
1622
1623         /*
1624          * Remove leaves stops at the first unmapped entry, so we have to
1625          * loop round finding mapped ranges.
1626          */
1627         while (begin < end) {
1628                 r = dm_btree_lookup_next(&pmd->bl_info, mapping_root, &begin, &begin, &value);
1629                 if (r == -ENODATA)
1630                         break;
1631
1632                 if (r)
1633                         return r;
1634
1635                 if (begin >= end)
1636                         break;
1637
1638                 r = dm_btree_remove_leaves(&pmd->bl_info, mapping_root, &begin, end, &mapping_root, &count);
1639                 if (r)
1640                         return r;
1641
1642                 total_count += count;
1643         }
1644
1645         td->mapped_blocks -= total_count;
1646         td->changed = 1;
1647
1648         /*
1649          * Reinsert the mapping tree.
1650          */
1651         value = cpu_to_le64(mapping_root);
1652         __dm_bless_for_disk(&value);
1653         return dm_btree_insert(&pmd->tl_info, pmd->root, keys, &value, &pmd->root);
1654 }
1655
1656 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block)
1657 {
1658         int r = -EINVAL;
1659
1660         down_write(&td->pmd->root_lock);
1661         if (!td->pmd->fail_io)
1662                 r = __remove(td, block);
1663         up_write(&td->pmd->root_lock);
1664
1665         return r;
1666 }
1667
1668 int dm_thin_remove_range(struct dm_thin_device *td,
1669                          dm_block_t begin, dm_block_t end)
1670 {
1671         int r = -EINVAL;
1672
1673         down_write(&td->pmd->root_lock);
1674         if (!td->pmd->fail_io)
1675                 r = __remove_range(td, begin, end);
1676         up_write(&td->pmd->root_lock);
1677
1678         return r;
1679 }
1680
1681 int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result)
1682 {
1683         int r;
1684         uint32_t ref_count;
1685
1686         down_read(&pmd->root_lock);
1687         r = dm_sm_get_count(pmd->data_sm, b, &ref_count);
1688         if (!r)
1689                 *result = (ref_count != 0);
1690         up_read(&pmd->root_lock);
1691
1692         return r;
1693 }
1694
1695 int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
1696 {
1697         int r = 0;
1698
1699         down_write(&pmd->root_lock);
1700         for (; b != e; b++) {
1701                 r = dm_sm_inc_block(pmd->data_sm, b);
1702                 if (r)
1703                         break;
1704         }
1705         up_write(&pmd->root_lock);
1706
1707         return r;
1708 }
1709
1710 int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
1711 {
1712         int r = 0;
1713
1714         down_write(&pmd->root_lock);
1715         for (; b != e; b++) {
1716                 r = dm_sm_dec_block(pmd->data_sm, b);
1717                 if (r)
1718                         break;
1719         }
1720         up_write(&pmd->root_lock);
1721
1722         return r;
1723 }
1724
1725 bool dm_thin_changed_this_transaction(struct dm_thin_device *td)
1726 {
1727         int r;
1728
1729         down_read(&td->pmd->root_lock);
1730         r = td->changed;
1731         up_read(&td->pmd->root_lock);
1732
1733         return r;
1734 }
1735
1736 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd)
1737 {
1738         bool r = false;
1739         struct dm_thin_device *td, *tmp;
1740
1741         down_read(&pmd->root_lock);
1742         list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
1743                 if (td->changed) {
1744                         r = td->changed;
1745                         break;
1746                 }
1747         }
1748         up_read(&pmd->root_lock);
1749
1750         return r;
1751 }
1752
1753 bool dm_thin_aborted_changes(struct dm_thin_device *td)
1754 {
1755         bool r;
1756
1757         down_read(&td->pmd->root_lock);
1758         r = td->aborted_with_changes;
1759         up_read(&td->pmd->root_lock);
1760
1761         return r;
1762 }
1763
1764 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result)
1765 {
1766         int r = -EINVAL;
1767
1768         down_write(&pmd->root_lock);
1769         if (!pmd->fail_io)
1770                 r = dm_sm_new_block(pmd->data_sm, result);
1771         up_write(&pmd->root_lock);
1772
1773         return r;
1774 }
1775
1776 int dm_pool_commit_metadata(struct dm_pool_metadata *pmd)
1777 {
1778         int r = -EINVAL;
1779
1780         down_write(&pmd->root_lock);
1781         if (pmd->fail_io)
1782                 goto out;
1783
1784         r = __commit_transaction(pmd);
1785         if (r <= 0)
1786                 goto out;
1787
1788         /*
1789          * Open the next transaction.
1790          */
1791         r = __begin_transaction(pmd);
1792 out:
1793         up_write(&pmd->root_lock);
1794         return r;
1795 }
1796
1797 static void __set_abort_with_changes_flags(struct dm_pool_metadata *pmd)
1798 {
1799         struct dm_thin_device *td;
1800
1801         list_for_each_entry(td, &pmd->thin_devices, list)
1802                 td->aborted_with_changes = td->changed;
1803 }
1804
1805 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd)
1806 {
1807         int r = -EINVAL;
1808
1809         down_write(&pmd->root_lock);
1810         if (pmd->fail_io)
1811                 goto out;
1812
1813         __set_abort_with_changes_flags(pmd);
1814         __destroy_persistent_data_objects(pmd);
1815         r = __create_persistent_data_objects(pmd, false);
1816         if (r)
1817                 pmd->fail_io = true;
1818
1819 out:
1820         up_write(&pmd->root_lock);
1821
1822         return r;
1823 }
1824
1825 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd, dm_block_t *result)
1826 {
1827         int r = -EINVAL;
1828
1829         down_read(&pmd->root_lock);
1830         if (!pmd->fail_io)
1831                 r = dm_sm_get_nr_free(pmd->data_sm, result);
1832         up_read(&pmd->root_lock);
1833
1834         return r;
1835 }
1836
1837 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
1838                                           dm_block_t *result)
1839 {
1840         int r = -EINVAL;
1841
1842         down_read(&pmd->root_lock);
1843         if (!pmd->fail_io)
1844                 r = dm_sm_get_nr_free(pmd->metadata_sm, result);
1845
1846         if (!r) {
1847                 if (*result < pmd->metadata_reserve)
1848                         *result = 0;
1849                 else
1850                         *result -= pmd->metadata_reserve;
1851         }
1852         up_read(&pmd->root_lock);
1853
1854         return r;
1855 }
1856
1857 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
1858                                   dm_block_t *result)
1859 {
1860         int r = -EINVAL;
1861
1862         down_read(&pmd->root_lock);
1863         if (!pmd->fail_io)
1864                 r = dm_sm_get_nr_blocks(pmd->metadata_sm, result);
1865         up_read(&pmd->root_lock);
1866
1867         return r;
1868 }
1869
1870 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result)
1871 {
1872         int r = -EINVAL;
1873
1874         down_read(&pmd->root_lock);
1875         if (!pmd->fail_io)
1876                 r = dm_sm_get_nr_blocks(pmd->data_sm, result);
1877         up_read(&pmd->root_lock);
1878
1879         return r;
1880 }
1881
1882 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result)
1883 {
1884         int r = -EINVAL;
1885         struct dm_pool_metadata *pmd = td->pmd;
1886
1887         down_read(&pmd->root_lock);
1888         if (!pmd->fail_io) {
1889                 *result = td->mapped_blocks;
1890                 r = 0;
1891         }
1892         up_read(&pmd->root_lock);
1893
1894         return r;
1895 }
1896
1897 static int __highest_block(struct dm_thin_device *td, dm_block_t *result)
1898 {
1899         int r;
1900         __le64 value_le;
1901         dm_block_t thin_root;
1902         struct dm_pool_metadata *pmd = td->pmd;
1903
1904         r = dm_btree_lookup(&pmd->tl_info, pmd->root, &td->id, &value_le);
1905         if (r)
1906                 return r;
1907
1908         thin_root = le64_to_cpu(value_le);
1909
1910         return dm_btree_find_highest_key(&pmd->bl_info, thin_root, result);
1911 }
1912
1913 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
1914                                      dm_block_t *result)
1915 {
1916         int r = -EINVAL;
1917         struct dm_pool_metadata *pmd = td->pmd;
1918
1919         down_read(&pmd->root_lock);
1920         if (!pmd->fail_io)
1921                 r = __highest_block(td, result);
1922         up_read(&pmd->root_lock);
1923
1924         return r;
1925 }
1926
1927 static int __resize_space_map(struct dm_space_map *sm, dm_block_t new_count)
1928 {
1929         int r;
1930         dm_block_t old_count;
1931
1932         r = dm_sm_get_nr_blocks(sm, &old_count);
1933         if (r)
1934                 return r;
1935
1936         if (new_count == old_count)
1937                 return 0;
1938
1939         if (new_count < old_count) {
1940                 DMERR("cannot reduce size of space map");
1941                 return -EINVAL;
1942         }
1943
1944         return dm_sm_extend(sm, new_count - old_count);
1945 }
1946
1947 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
1948 {
1949         int r = -EINVAL;
1950
1951         down_write(&pmd->root_lock);
1952         if (!pmd->fail_io)
1953                 r = __resize_space_map(pmd->data_sm, new_count);
1954         up_write(&pmd->root_lock);
1955
1956         return r;
1957 }
1958
1959 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
1960 {
1961         int r = -EINVAL;
1962
1963         down_write(&pmd->root_lock);
1964         if (!pmd->fail_io) {
1965                 r = __resize_space_map(pmd->metadata_sm, new_count);
1966                 if (!r)
1967                         __set_metadata_reserve(pmd);
1968         }
1969         up_write(&pmd->root_lock);
1970
1971         return r;
1972 }
1973
1974 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd)
1975 {
1976         down_write(&pmd->root_lock);
1977         dm_bm_set_read_only(pmd->bm);
1978         up_write(&pmd->root_lock);
1979 }
1980
1981 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd)
1982 {
1983         down_write(&pmd->root_lock);
1984         dm_bm_set_read_write(pmd->bm);
1985         up_write(&pmd->root_lock);
1986 }
1987
1988 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
1989                                         dm_block_t threshold,
1990                                         dm_sm_threshold_fn fn,
1991                                         void *context)
1992 {
1993         int r;
1994
1995         down_write(&pmd->root_lock);
1996         r = dm_sm_register_threshold_callback(pmd->metadata_sm, threshold, fn, context);
1997         up_write(&pmd->root_lock);
1998
1999         return r;
2000 }
2001
2002 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd)
2003 {
2004         int r;
2005         struct dm_block *sblock;
2006         struct thin_disk_superblock *disk_super;
2007
2008         down_write(&pmd->root_lock);
2009         pmd->flags |= THIN_METADATA_NEEDS_CHECK_FLAG;
2010
2011         r = superblock_lock(pmd, &sblock);
2012         if (r) {
2013                 DMERR("couldn't read superblock");
2014                 goto out;
2015         }
2016
2017         disk_super = dm_block_data(sblock);
2018         disk_super->flags = cpu_to_le32(pmd->flags);
2019
2020         dm_bm_unlock(sblock);
2021 out:
2022         up_write(&pmd->root_lock);
2023         return r;
2024 }
2025
2026 bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd)
2027 {
2028         bool needs_check;
2029
2030         down_read(&pmd->root_lock);
2031         needs_check = pmd->flags & THIN_METADATA_NEEDS_CHECK_FLAG;
2032         up_read(&pmd->root_lock);
2033
2034         return needs_check;
2035 }
2036
2037 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd)
2038 {
2039         down_read(&pmd->root_lock);
2040         if (!pmd->fail_io)
2041                 dm_tm_issue_prefetches(pmd->tm);
2042         up_read(&pmd->root_lock);
2043 }