drivers/md/dm-era-target.c

   1 #include "dm.h"
   2 #include "persistent-data/dm-transaction-manager.h"
   3 #include "persistent-data/dm-bitset.h"
   4 #include "persistent-data/dm-space-map.h"
   5
   6 #include <linux/dm-io.h>
   7 #include <linux/dm-kcopyd.h>
   8 #include <linux/init.h>
   9 #include <linux/mempool.h>
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/vmalloc.h>
  13
  14 #define DM_MSG_PREFIX "era"
  15
  16 #define SUPERBLOCK_LOCATION 0
  17 #define SUPERBLOCK_MAGIC 2126579579
  18 #define SUPERBLOCK_CSUM_XOR 146538381
  19 #define MIN_ERA_VERSION 1
  20 #define MAX_ERA_VERSION 1
  21 #define INVALID_WRITESET_ROOT SUPERBLOCK_LOCATION
  22 #define MIN_BLOCK_SIZE 8
  23
  24 /*----------------------------------------------------------------
  25  * Writeset
  26  *--------------------------------------------------------------*/
  27 struct writeset_metadata {
  28         uint32_t nr_bits;
  29         dm_block_t root;
  30 };
  31
  32 struct writeset {
  33         struct writeset_metadata md;
  34
  35         /*
  36          * An in core copy of the bits to save constantly doing look ups on
  37          * disk.
  38          */
  39         unsigned long *bits;
  40 };
  41
  42 /*
  43  * This does not free off the on disk bitset as this will normally be done
  44  * after digesting into the era array.
  45  */
  46 static void writeset_free(struct writeset *ws)
  47 {
  48         vfree(ws->bits);
  49 }
  50
  51 static int setup_on_disk_bitset(struct dm_disk_bitset *info,
  52                                 unsigned nr_bits, dm_block_t *root)
  53 {
  54         int r;
  55
  56         r = dm_bitset_empty(info, root);
  57         if (r)
  58                 return r;
  59
  60         return dm_bitset_resize(info, *root, 0, nr_bits, false, root);
  61 }
  62
  63 static size_t bitset_size(unsigned nr_bits)
  64 {
  65         return sizeof(unsigned long) * dm_div_up(nr_bits, BITS_PER_LONG);
  66 }
  67
  68 /*
  69  * Allocates memory for the in core bitset.
  70  */
  71 static int writeset_alloc(struct writeset *ws, dm_block_t nr_blocks)
  72 {
  73         ws->md.nr_bits = nr_blocks;
  74         ws->md.root = INVALID_WRITESET_ROOT;
  75         ws->bits = vzalloc(bitset_size(nr_blocks));
  76         if (!ws->bits) {
  77                 DMERR("%s: couldn't allocate in memory bitset", __func__);
  78                 return -ENOMEM;
  79         }
  80
  81         return 0;
  82 }
  83
  84 /*
  85  * Wipes the in-core bitset, and creates a new on disk bitset.
  86  */
  87 static int writeset_init(struct dm_disk_bitset *info, struct writeset *ws)
  88 {
  89         int r;
  90
  91         memset(ws->bits, 0, bitset_size(ws->md.nr_bits));
  92
  93         r = setup_on_disk_bitset(info, ws->md.nr_bits, &ws->md.root);
  94         if (r) {
  95                 DMERR("%s: setup_on_disk_bitset failed", __func__);
  96                 return r;
  97         }
  98
  99         return 0;
 100 }
 101
 102 static bool writeset_marked(struct writeset *ws, dm_block_t block)
 103 {
 104         return test_bit(block, ws->bits);
 105 }
 106
 107 static int writeset_marked_on_disk(struct dm_disk_bitset *info,
 108                                    struct writeset_metadata *m, dm_block_t block,
 109                                    bool *result)
 110 {
 111         dm_block_t old = m->root;
 112
 113         /*
 114          * The bitset was flushed when it was archived, so we know there'll
 115          * be no change to the root.
 116          */
 117         int r = dm_bitset_test_bit(info, m->root, block, &m->root, result);
 118         if (r) {
 119                 DMERR("%s: dm_bitset_test_bit failed", __func__);
 120                 return r;
 121         }
 122
 123         BUG_ON(m->root != old);
 124
 125         return r;
 126 }
 127
 128 /*
 129  * Returns < 0 on error, 0 if the bit wasn't previously set, 1 if it was.
 130  */
 131 static int writeset_test_and_set(struct dm_disk_bitset *info,
 132                                  struct writeset *ws, uint32_t block)
 133 {
 134         int r;
 135
 136         if (!test_and_set_bit(block, ws->bits)) {
 137                 r = dm_bitset_set_bit(info, ws->md.root, block, &ws->md.root);
 138                 if (r) {
 139                         /* FIXME: fail mode */
 140                         return r;
 141                 }
 142
 143                 return 0;
 144         }
 145
 146         return 1;
 147 }
 148
 149 /*----------------------------------------------------------------
 150  * On disk metadata layout
 151  *--------------------------------------------------------------*/
 152 #define SPACE_MAP_ROOT_SIZE 128
 153 #define UUID_LEN 16
 154
 155 struct writeset_disk {
 156         __le32 nr_bits;
 157         __le64 root;
 158 } __packed;
 159
 160 struct superblock_disk {
 161         __le32 csum;
 162         __le32 flags;
 163         __le64 blocknr;
 164
 165         __u8 uuid[UUID_LEN];
 166         __le64 magic;
 167         __le32 version;
 168
 169         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 170
 171         __le32 data_block_size;
 172         __le32 metadata_block_size;
 173         __le32 nr_blocks;
 174
 175         __le32 current_era;
 176         struct writeset_disk current_writeset;
 177
 178         /*
 179          * Only these two fields are valid within the metadata snapshot.
 180          */
 181         __le64 writeset_tree_root;
 182         __le64 era_array_root;
 183
 184         __le64 metadata_snap;
 185 } __packed;
 186
 187 /*----------------------------------------------------------------
 188  * Superblock validation
 189  *--------------------------------------------------------------*/
 190 static void sb_prepare_for_write(struct dm_block_validator *v,
 191                                  struct dm_block *b,
 192                                  size_t sb_block_size)
 193 {
 194         struct superblock_disk *disk = dm_block_data(b);
 195
 196         disk->blocknr = cpu_to_le64(dm_block_location(b));
 197         disk->csum = cpu_to_le32(dm_bm_checksum(&disk->flags,
 198                                                 sb_block_size - sizeof(__le32),
 199                                                 SUPERBLOCK_CSUM_XOR));
 200 }
 201
 202 static int check_metadata_version(struct superblock_disk *disk)
 203 {
 204         uint32_t metadata_version = le32_to_cpu(disk->version);
 205         if (metadata_version < MIN_ERA_VERSION || metadata_version > MAX_ERA_VERSION) {
 206                 DMERR("Era metadata version %u found, but only versions between %u and %u supported.",
 207                       metadata_version, MIN_ERA_VERSION, MAX_ERA_VERSION);
 208                 return -EINVAL;
 209         }
 210
 211         return 0;
 212 }
 213
 214 static int sb_check(struct dm_block_validator *v,
 215                     struct dm_block *b,
 216                     size_t sb_block_size)
 217 {
 218         struct superblock_disk *disk = dm_block_data(b);
 219         __le32 csum_le;
 220
 221         if (dm_block_location(b) != le64_to_cpu(disk->blocknr)) {
 222                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 223                       le64_to_cpu(disk->blocknr),
 224                       (unsigned long long)dm_block_location(b));
 225                 return -ENOTBLK;
 226         }
 227
 228         if (le64_to_cpu(disk->magic) != SUPERBLOCK_MAGIC) {
 229                 DMERR("sb_check failed: magic %llu: wanted %llu",
 230                       le64_to_cpu(disk->magic),
 231                       (unsigned long long) SUPERBLOCK_MAGIC);
 232                 return -EILSEQ;
 233         }
 234
 235         csum_le = cpu_to_le32(dm_bm_checksum(&disk->flags,
 236                                              sb_block_size - sizeof(__le32),
 237                                              SUPERBLOCK_CSUM_XOR));
 238         if (csum_le != disk->csum) {
 239                 DMERR("sb_check failed: csum %u: wanted %u",
 240                       le32_to_cpu(csum_le), le32_to_cpu(disk->csum));
 241                 return -EILSEQ;
 242         }
 243
 244         return check_metadata_version(disk);
 245 }
 246
 247 static struct dm_block_validator sb_validator = {
 248         .name = "superblock",
 249         .prepare_for_write = sb_prepare_for_write,
 250         .check = sb_check
 251 };
 252
 253 /*----------------------------------------------------------------
 254  * Low level metadata handling
 255  *--------------------------------------------------------------*/
 256 #define DM_ERA_METADATA_BLOCK_SIZE 4096
 257 #define ERA_MAX_CONCURRENT_LOCKS 5
 258
 259 struct era_metadata {
 260         struct block_device *bdev;
 261         struct dm_block_manager *bm;
 262         struct dm_space_map *sm;
 263         struct dm_transaction_manager *tm;
 264
 265         dm_block_t block_size;
 266         uint32_t nr_blocks;
 267
 268         uint32_t current_era;
 269
 270         /*
 271          * We preallocate 2 writesets.  When an era rolls over we
 272          * switch between them. This means the allocation is done at
 273          * preresume time, rather than on the io path.
 274          */
 275         struct writeset writesets[2];
 276         struct writeset *current_writeset;
 277
 278         dm_block_t writeset_tree_root;
 279         dm_block_t era_array_root;
 280
 281         struct dm_disk_bitset bitset_info;
 282         struct dm_btree_info writeset_tree_info;
 283         struct dm_array_info era_array_info;
 284
 285         dm_block_t metadata_snap;
 286
 287         /*
 288          * A flag that is set whenever a writeset has been archived.
 289          */
 290         bool archived_writesets;
 291
 292         /*
 293          * Reading the space map root can fail, so we read it into this
 294          * buffer before the superblock is locked and updated.
 295          */
 296         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 297 };
 298
 299 static int superblock_read_lock(struct era_metadata *md,
 300                                 struct dm_block **sblock)
 301 {
 302         return dm_bm_read_lock(md->bm, SUPERBLOCK_LOCATION,
 303                                &sb_validator, sblock);
 304 }
 305
 306 static int superblock_lock_zero(struct era_metadata *md,
 307                                 struct dm_block **sblock)
 308 {
 309         return dm_bm_write_lock_zero(md->bm, SUPERBLOCK_LOCATION,
 310                                      &sb_validator, sblock);
 311 }
 312
 313 static int superblock_lock(struct era_metadata *md,
 314                            struct dm_block **sblock)
 315 {
 316         return dm_bm_write_lock(md->bm, SUPERBLOCK_LOCATION,
 317                                 &sb_validator, sblock);
 318 }
 319
 320 /* FIXME: duplication with cache and thin */
 321 static int superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 322 {
 323         int r;
 324         unsigned i;
 325         struct dm_block *b;
 326         __le64 *data_le, zero = cpu_to_le64(0);
 327         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 328
 329         /*
 330          * We can't use a validator here - it may be all zeroes.
 331          */
 332         r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &b);
 333         if (r)
 334                 return r;
 335
 336         data_le = dm_block_data(b);
 337         *result = true;
 338         for (i = 0; i < sb_block_size; i++) {
 339                 if (data_le[i] != zero) {
 340                         *result = false;
 341                         break;
 342                 }
 343         }
 344
 345         dm_bm_unlock(b);
 346
 347         return 0;
 348 }
 349
 350 /*----------------------------------------------------------------*/
 351
 352 static void ws_pack(const struct writeset_metadata *core, struct writeset_disk *disk)
 353 {
 354         disk->nr_bits = cpu_to_le32(core->nr_bits);
 355         disk->root = cpu_to_le64(core->root);
 356 }
 357
 358 static void ws_unpack(const struct writeset_disk *disk, struct writeset_metadata *core)
 359 {
 360         core->nr_bits = le32_to_cpu(disk->nr_bits);
 361         core->root = le64_to_cpu(disk->root);
 362 }
 363
 364 static void ws_inc(void *context, const void *value)
 365 {
 366         struct era_metadata *md = context;
 367         struct writeset_disk ws_d;
 368         dm_block_t b;
 369
 370         memcpy(&ws_d, value, sizeof(ws_d));
 371         b = le64_to_cpu(ws_d.root);
 372
 373         dm_tm_inc(md->tm, b);
 374 }
 375
 376 static void ws_dec(void *context, const void *value)
 377 {
 378         struct era_metadata *md = context;
 379         struct writeset_disk ws_d;
 380         dm_block_t b;
 381
 382         memcpy(&ws_d, value, sizeof(ws_d));
 383         b = le64_to_cpu(ws_d.root);
 384
 385         dm_bitset_del(&md->bitset_info, b);
 386 }
 387
 388 static int ws_eq(void *context, const void *value1, const void *value2)
 389 {
 390         return !memcmp(value1, value2, sizeof(struct writeset_metadata));
 391 }
 392
 393 /*----------------------------------------------------------------*/
 394
 395 static void setup_writeset_tree_info(struct era_metadata *md)
 396 {
 397         struct dm_btree_value_type *vt = &md->writeset_tree_info.value_type;
 398         md->writeset_tree_info.tm = md->tm;
 399         md->writeset_tree_info.levels = 1;
 400         vt->context = md;
 401         vt->size = sizeof(struct writeset_disk);
 402         vt->inc = ws_inc;
 403         vt->dec = ws_dec;
 404         vt->equal = ws_eq;
 405 }
 406
 407 static void setup_era_array_info(struct era_metadata *md)
 408
 409 {
 410         struct dm_btree_value_type vt;
 411         vt.context = NULL;
 412         vt.size = sizeof(__le32);
 413         vt.inc = NULL;
 414         vt.dec = NULL;
 415         vt.equal = NULL;
 416
 417         dm_array_info_init(&md->era_array_info, md->tm, &vt);
 418 }
 419
 420 static void setup_infos(struct era_metadata *md)
 421 {
 422         dm_disk_bitset_init(md->tm, &md->bitset_info);
 423         setup_writeset_tree_info(md);
 424         setup_era_array_info(md);
 425 }
 426
 427 /*----------------------------------------------------------------*/
 428
 429 static int create_fresh_metadata(struct era_metadata *md)
 430 {
 431         int r;
 432
 433         r = dm_tm_create_with_sm(md->bm, SUPERBLOCK_LOCATION,
 434                                  &md->tm, &md->sm);
 435         if (r < 0) {
 436                 DMERR("dm_tm_create_with_sm failed");
 437                 return r;
 438         }
 439
 440         setup_infos(md);
 441
 442         r = dm_btree_empty(&md->writeset_tree_info, &md->writeset_tree_root);
 443         if (r) {
 444                 DMERR("couldn't create new writeset tree");
 445                 goto bad;
 446         }
 447
 448         r = dm_array_empty(&md->era_array_info, &md->era_array_root);
 449         if (r) {
 450                 DMERR("couldn't create era array");
 451                 goto bad;
 452         }
 453
 454         return 0;
 455
 456 bad:
 457         dm_sm_destroy(md->sm);
 458         dm_tm_destroy(md->tm);
 459
 460         return r;
 461 }
 462
 463 static int save_sm_root(struct era_metadata *md)
 464 {
 465         int r;
 466         size_t metadata_len;
 467
 468         r = dm_sm_root_size(md->sm, &metadata_len);
 469         if (r < 0)
 470                 return r;
 471
 472         return dm_sm_copy_root(md->sm, &md->metadata_space_map_root,
 473                                metadata_len);
 474 }
 475
 476 static void copy_sm_root(struct era_metadata *md, struct superblock_disk *disk)
 477 {
 478         memcpy(&disk->metadata_space_map_root,
 479                &md->metadata_space_map_root,
 480                sizeof(md->metadata_space_map_root));
 481 }
 482
 483 /*
 484  * Writes a superblock, including the static fields that don't get updated
 485  * with every commit (possible optimisation here).  'md' should be fully
 486  * constructed when this is called.
 487  */
 488 static void prepare_superblock(struct era_metadata *md, struct superblock_disk *disk)
 489 {
 490         disk->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
 491         disk->flags = cpu_to_le32(0ul);
 492
 493         /* FIXME: can't keep blanking the uuid (uuid is currently unused though) */
 494         memset(disk->uuid, 0, sizeof(disk->uuid));
 495         disk->version = cpu_to_le32(MAX_ERA_VERSION);
 496
 497         copy_sm_root(md, disk);
 498
 499         disk->data_block_size = cpu_to_le32(md->block_size);
 500         disk->metadata_block_size = cpu_to_le32(DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 501         disk->nr_blocks = cpu_to_le32(md->nr_blocks);
 502         disk->current_era = cpu_to_le32(md->current_era);
 503
 504         ws_pack(&md->current_writeset->md, &disk->current_writeset);
 505         disk->writeset_tree_root = cpu_to_le64(md->writeset_tree_root);
 506         disk->era_array_root = cpu_to_le64(md->era_array_root);
 507         disk->metadata_snap = cpu_to_le64(md->metadata_snap);
 508 }
 509
 510 static int write_superblock(struct era_metadata *md)
 511 {
 512         int r;
 513         struct dm_block *sblock;
 514         struct superblock_disk *disk;
 515
 516         r = save_sm_root(md);
 517         if (r) {
 518                 DMERR("%s: save_sm_root failed", __func__);
 519                 return r;
 520         }
 521
 522         r = superblock_lock_zero(md, &sblock);
 523         if (r)
 524                 return r;
 525
 526         disk = dm_block_data(sblock);
 527         prepare_superblock(md, disk);
 528
 529         return dm_tm_commit(md->tm, sblock);
 530 }
 531
 532 /*
 533  * Assumes block_size and the infos are set.
 534  */
 535 static int format_metadata(struct era_metadata *md)
 536 {
 537         int r;
 538
 539         r = create_fresh_metadata(md);
 540         if (r)
 541                 return r;
 542
 543         r = write_superblock(md);
 544         if (r) {
 545                 dm_sm_destroy(md->sm);
 546                 dm_tm_destroy(md->tm);
 547                 return r;
 548         }
 549
 550         return 0;
 551 }
 552
 553 static int open_metadata(struct era_metadata *md)
 554 {
 555         int r;
 556         struct dm_block *sblock;
 557         struct superblock_disk *disk;
 558
 559         r = superblock_read_lock(md, &sblock);
 560         if (r) {
 561                 DMERR("couldn't read_lock superblock");
 562                 return r;
 563         }
 564
 565         disk = dm_block_data(sblock);
 566         r = dm_tm_open_with_sm(md->bm, SUPERBLOCK_LOCATION,
 567                                disk->metadata_space_map_root,
 568                                sizeof(disk->metadata_space_map_root),
 569                                &md->tm, &md->sm);
 570         if (r) {
 571                 DMERR("dm_tm_open_with_sm failed");
 572                 goto bad;
 573         }
 574
 575         setup_infos(md);
 576
 577         md->block_size = le32_to_cpu(disk->data_block_size);
 578         md->nr_blocks = le32_to_cpu(disk->nr_blocks);
 579         md->current_era = le32_to_cpu(disk->current_era);
 580
 581         md->writeset_tree_root = le64_to_cpu(disk->writeset_tree_root);
 582         md->era_array_root = le64_to_cpu(disk->era_array_root);
 583         md->metadata_snap = le64_to_cpu(disk->metadata_snap);
 584         md->archived_writesets = true;
 585
 586         dm_bm_unlock(sblock);
 587
 588         return 0;
 589
 590 bad:
 591         dm_bm_unlock(sblock);
 592         return r;
 593 }
 594
 595 static int open_or_format_metadata(struct era_metadata *md,
 596                                    bool may_format)
 597 {
 598         int r;
 599         bool unformatted = false;
 600
 601         r = superblock_all_zeroes(md->bm, &unformatted);
 602         if (r)
 603                 return r;
 604
 605         if (unformatted)
 606                 return may_format ? format_metadata(md) : -EPERM;
 607
 608         return open_metadata(md);
 609 }
 610
 611 static int create_persistent_data_objects(struct era_metadata *md,
 612                                           bool may_format)
 613 {
 614         int r;
 615
 616         md->bm = dm_block_manager_create(md->bdev, DM_ERA_METADATA_BLOCK_SIZE,
 617                                          ERA_MAX_CONCURRENT_LOCKS);
 618         if (IS_ERR(md->bm)) {
 619                 DMERR("could not create block manager");
 620                 return PTR_ERR(md->bm);
 621         }
 622
 623         r = open_or_format_metadata(md, may_format);
 624         if (r)
 625                 dm_block_manager_destroy(md->bm);
 626
 627         return r;
 628 }
 629
 630 static void destroy_persistent_data_objects(struct era_metadata *md)
 631 {
 632         dm_sm_destroy(md->sm);
 633         dm_tm_destroy(md->tm);
 634         dm_block_manager_destroy(md->bm);
 635 }
 636
 637 /*
 638  * This waits until all era_map threads have picked up the new filter.
 639  */
 640 static void swap_writeset(struct era_metadata *md, struct writeset *new_writeset)
 641 {
 642         rcu_assign_pointer(md->current_writeset, new_writeset);
 643         synchronize_rcu();
 644 }
 645
 646 /*----------------------------------------------------------------
 647  * Writesets get 'digested' into the main era array.
 648  *
 649  * We're using a coroutine here so the worker thread can do the digestion,
 650  * thus avoiding synchronisation of the metadata.  Digesting a whole
 651  * writeset in one go would cause too much latency.
 652  *--------------------------------------------------------------*/
 653 struct digest {
 654         uint32_t era;
 655         unsigned nr_bits, current_bit;
 656         struct writeset_metadata writeset;
 657         __le32 value;
 658         struct dm_disk_bitset info;
 659
 660         int (*step)(struct era_metadata *, struct digest *);
 661 };
 662
 663 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 664                                            struct digest *d);
 665
 666 static int metadata_digest_remove_writeset(struct era_metadata *md,
 667                                            struct digest *d)
 668 {
 669         int r;
 670         uint64_t key = d->era;
 671
 672         r = dm_btree_remove(&md->writeset_tree_info, md->writeset_tree_root,
 673                             &key, &md->writeset_tree_root);
 674         if (r) {
 675                 DMERR("%s: dm_btree_remove failed", __func__);
 676                 return r;
 677         }
 678
 679         d->step = metadata_digest_lookup_writeset;
 680         return 0;
 681 }
 682
 683 #define INSERTS_PER_STEP 100
 684
 685 static int metadata_digest_transcribe_writeset(struct era_metadata *md,
 686                                                struct digest *d)
 687 {
 688         int r;
 689         bool marked;
 690         unsigned b, e = min(d->current_bit + INSERTS_PER_STEP, d->nr_bits);
 691
 692         for (b = d->current_bit; b < e; b++) {
 693                 r = writeset_marked_on_disk(&d->info, &d->writeset, b, &marked);
 694                 if (r) {
 695                         DMERR("%s: writeset_marked_on_disk failed", __func__);
 696                         return r;
 697                 }
 698
 699                 if (!marked)
 700                         continue;
 701
 702                 __dm_bless_for_disk(&d->value);
 703                 r = dm_array_set_value(&md->era_array_info, md->era_array_root,
 704                                        b, &d->value, &md->era_array_root);
 705                 if (r) {
 706                         DMERR("%s: dm_array_set_value failed", __func__);
 707                         return r;
 708                 }
 709         }
 710
 711         if (b == d->nr_bits)
 712                 d->step = metadata_digest_remove_writeset;
 713         else
 714                 d->current_bit = b;
 715
 716         return 0;
 717 }
 718
 719 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 720                                            struct digest *d)
 721 {
 722         int r;
 723         uint64_t key;
 724         struct writeset_disk disk;
 725
 726         r = dm_btree_find_lowest_key(&md->writeset_tree_info,
 727                                      md->writeset_tree_root, &key);
 728         if (r < 0)
 729                 return r;
 730
 731         d->era = key;
 732
 733         r = dm_btree_lookup(&md->writeset_tree_info,
 734                             md->writeset_tree_root, &key, &disk);
 735         if (r) {
 736                 if (r == -ENODATA) {
 737                         d->step = NULL;
 738                         return 0;
 739                 }
 740
 741                 DMERR("%s: dm_btree_lookup failed", __func__);
 742                 return r;
 743         }
 744
 745         ws_unpack(&disk, &d->writeset);
 746         d->value = cpu_to_le32(key);
 747
 748         d->nr_bits = min(d->writeset.nr_bits, md->nr_blocks);
 749         d->current_bit = 0;
 750         d->step = metadata_digest_transcribe_writeset;
 751
 752         return 0;
 753 }
 754
 755 static int metadata_digest_start(struct era_metadata *md, struct digest *d)
 756 {
 757         if (d->step)
 758                 return 0;
 759
 760         memset(d, 0, sizeof(*d));
 761
 762         /*
 763          * We initialise another bitset info to avoid any caching side
 764          * effects with the previous one.
 765          */
 766         dm_disk_bitset_init(md->tm, &d->info);
 767         d->step = metadata_digest_lookup_writeset;
 768
 769         return 0;
 770 }
 771
 772 /*----------------------------------------------------------------
 773  * High level metadata interface.  Target methods should use these, and not
 774  * the lower level ones.
 775  *--------------------------------------------------------------*/
 776 static struct era_metadata *metadata_open(struct block_device *bdev,
 777                                           sector_t block_size,
 778                                           bool may_format)
 779 {
 780         int r;
 781         struct era_metadata *md = kzalloc(sizeof(*md), GFP_KERNEL);
 782
 783         if (!md)
 784                 return NULL;
 785
 786         md->bdev = bdev;
 787         md->block_size = block_size;
 788
 789         md->writesets[0].md.root = INVALID_WRITESET_ROOT;
 790         md->writesets[1].md.root = INVALID_WRITESET_ROOT;
 791         md->current_writeset = &md->writesets[0];
 792
 793         r = create_persistent_data_objects(md, may_format);
 794         if (r) {
 795                 kfree(md);
 796                 return ERR_PTR(r);
 797         }
 798
 799         return md;
 800 }
 801
 802 static void metadata_close(struct era_metadata *md)
 803 {
 804         destroy_persistent_data_objects(md);
 805         kfree(md);
 806 }
 807
 808 static bool valid_nr_blocks(dm_block_t n)
 809 {
 810         /*
 811          * dm_bitset restricts us to 2^32.  test_bit & co. restrict us
 812          * further to 2^31 - 1
 813          */
 814         return n < (1ull << 31);
 815 }
 816
 817 static int metadata_resize(struct era_metadata *md, void *arg)
 818 {
 819         int r;
 820         dm_block_t *new_size = arg;
 821         __le32 value;
 822
 823         if (!valid_nr_blocks(*new_size)) {
 824                 DMERR("Invalid number of origin blocks %llu",
 825                       (unsigned long long) *new_size);
 826                 return -EINVAL;
 827         }
 828
 829         writeset_free(&md->writesets[0]);
 830         writeset_free(&md->writesets[1]);
 831
 832         r = writeset_alloc(&md->writesets[0], *new_size);
 833         if (r) {
 834                 DMERR("%s: writeset_alloc failed for writeset 0", __func__);
 835                 return r;
 836         }
 837
 838         r = writeset_alloc(&md->writesets[1], *new_size);
 839         if (r) {
 840                 DMERR("%s: writeset_alloc failed for writeset 1", __func__);
 841                 return r;
 842         }
 843
 844         value = cpu_to_le32(0u);
 845         __dm_bless_for_disk(&value);
 846         r = dm_array_resize(&md->era_array_info, md->era_array_root,
 847                             md->nr_blocks, *new_size,
 848                             &value, &md->era_array_root);
 849         if (r) {
 850                 DMERR("%s: dm_array_resize failed", __func__);
 851                 return r;
 852         }
 853
 854         md->nr_blocks = *new_size;
 855         return 0;
 856 }
 857
 858 static int metadata_era_archive(struct era_metadata *md)
 859 {
 860         int r;
 861         uint64_t keys[1];
 862         struct writeset_disk value;
 863
 864         r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 865                             &md->current_writeset->md.root);
 866         if (r) {
 867                 DMERR("%s: dm_bitset_flush failed", __func__);
 868                 return r;
 869         }
 870
 871         ws_pack(&md->current_writeset->md, &value);
 872         md->current_writeset->md.root = INVALID_WRITESET_ROOT;
 873
 874         keys[0] = md->current_era;
 875         __dm_bless_for_disk(&value);
 876         r = dm_btree_insert(&md->writeset_tree_info, md->writeset_tree_root,
 877                             keys, &value, &md->writeset_tree_root);
 878         if (r) {
 879                 DMERR("%s: couldn't insert writeset into btree", __func__);
 880                 /* FIXME: fail mode */
 881                 return r;
 882         }
 883
 884         md->archived_writesets = true;
 885
 886         return 0;
 887 }
 888
 889 static struct writeset *next_writeset(struct era_metadata *md)
 890 {
 891         return (md->current_writeset == &md->writesets[0]) ?
 892                 &md->writesets[1] : &md->writesets[0];
 893 }
 894
 895 static int metadata_new_era(struct era_metadata *md)
 896 {
 897         int r;
 898         struct writeset *new_writeset = next_writeset(md);
 899
 900         r = writeset_init(&md->bitset_info, new_writeset);
 901         if (r) {
 902                 DMERR("%s: writeset_init failed", __func__);
 903                 return r;
 904         }
 905
 906         swap_writeset(md, new_writeset);
 907         md->current_era++;
 908
 909         return 0;
 910 }
 911
 912 static int metadata_era_rollover(struct era_metadata *md)
 913 {
 914         int r;
 915
 916         if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 917                 r = metadata_era_archive(md);
 918                 if (r) {
 919                         DMERR("%s: metadata_archive_era failed", __func__);
 920                         /* FIXME: fail mode? */
 921                         return r;
 922                 }
 923         }
 924
 925         r = metadata_new_era(md);
 926         if (r) {
 927                 DMERR("%s: new era failed", __func__);
 928                 /* FIXME: fail mode */
 929                 return r;
 930         }
 931
 932         return 0;
 933 }
 934
 935 static bool metadata_current_marked(struct era_metadata *md, dm_block_t block)
 936 {
 937         bool r;
 938         struct writeset *ws;
 939
 940         rcu_read_lock();
 941         ws = rcu_dereference(md->current_writeset);
 942         r = writeset_marked(ws, block);
 943         rcu_read_unlock();
 944
 945         return r;
 946 }
 947
 948 static int metadata_commit(struct era_metadata *md)
 949 {
 950         int r;
 951         struct dm_block *sblock;
 952
 953         if (md->current_writeset->md.root != SUPERBLOCK_LOCATION) {
 954                 r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 955                                     &md->current_writeset->md.root);
 956                 if (r) {
 957                         DMERR("%s: bitset flush failed", __func__);
 958                         return r;
 959                 }
 960         }
 961
 962         r = dm_tm_pre_commit(md->tm);
 963         if (r) {
 964                 DMERR("%s: pre commit failed", __func__);
 965                 return r;
 966         }
 967
 968         r = save_sm_root(md);
 969         if (r) {
 970                 DMERR("%s: save_sm_root failed", __func__);
 971                 return r;
 972         }
 973
 974         r = superblock_lock(md, &sblock);
 975         if (r) {
 976                 DMERR("%s: superblock lock failed", __func__);
 977                 return r;
 978         }
 979
 980         prepare_superblock(md, dm_block_data(sblock));
 981
 982         return dm_tm_commit(md->tm, sblock);
 983 }
 984
 985 static int metadata_checkpoint(struct era_metadata *md)
 986 {
 987         /*
 988          * For now we just rollover, but later I want to put a check in to
 989          * avoid this if the filter is still pretty fresh.
 990          */
 991         return metadata_era_rollover(md);
 992 }
 993
 994 /*
 995  * Metadata snapshots allow userland to access era data.
 996  */
 997 static int metadata_take_snap(struct era_metadata *md)
 998 {
 999         int r, inc;
1000         struct dm_block *clone;
1001
1002         if (md->metadata_snap != SUPERBLOCK_LOCATION) {
1003                 DMERR("%s: metadata snapshot already exists", __func__);
1004                 return -EINVAL;
1005         }
1006
1007         r = metadata_era_rollover(md);
1008         if (r) {
1009                 DMERR("%s: era rollover failed", __func__);
1010                 return r;
1011         }
1012
1013         r = metadata_commit(md);
1014         if (r) {
1015                 DMERR("%s: pre commit failed", __func__);
1016                 return r;
1017         }
1018
1019         r = dm_sm_inc_block(md->sm, SUPERBLOCK_LOCATION);
1020         if (r) {
1021                 DMERR("%s: couldn't increment superblock", __func__);
1022                 return r;
1023         }
1024
1025         r = dm_tm_shadow_block(md->tm, SUPERBLOCK_LOCATION,
1026                                &sb_validator, &clone, &inc);
1027         if (r) {
1028                 DMERR("%s: couldn't shadow superblock", __func__);
1029                 dm_sm_dec_block(md->sm, SUPERBLOCK_LOCATION);
1030                 return r;
1031         }
1032         BUG_ON(!inc);
1033
1034         r = dm_sm_inc_block(md->sm, md->writeset_tree_root);
1035         if (r) {
1036                 DMERR("%s: couldn't inc writeset tree root", __func__);
1037                 dm_tm_unlock(md->tm, clone);
1038                 return r;
1039         }
1040
1041         r = dm_sm_inc_block(md->sm, md->era_array_root);
1042         if (r) {
1043                 DMERR("%s: couldn't inc era tree root", __func__);
1044                 dm_sm_dec_block(md->sm, md->writeset_tree_root);
1045                 dm_tm_unlock(md->tm, clone);
1046                 return r;
1047         }
1048
1049         md->metadata_snap = dm_block_location(clone);
1050
1051         dm_tm_unlock(md->tm, clone);
1052
1053         return 0;
1054 }
1055
1056 static int metadata_drop_snap(struct era_metadata *md)
1057 {
1058         int r;
1059         dm_block_t location;
1060         struct dm_block *clone;
1061         struct superblock_disk *disk;
1062
1063         if (md->metadata_snap == SUPERBLOCK_LOCATION) {
1064                 DMERR("%s: no snap to drop", __func__);
1065                 return -EINVAL;
1066         }
1067
1068         r = dm_tm_read_lock(md->tm, md->metadata_snap, &sb_validator, &clone);
1069         if (r) {
1070                 DMERR("%s: couldn't read lock superblock clone", __func__);
1071                 return r;
1072         }
1073
1074         /*
1075          * Whatever happens now we'll commit with no record of the metadata
1076          * snap.
1077          */
1078         md->metadata_snap = SUPERBLOCK_LOCATION;
1079
1080         disk = dm_block_data(clone);
1081         r = dm_btree_del(&md->writeset_tree_info,
1082                          le64_to_cpu(disk->writeset_tree_root));
1083         if (r) {
1084                 DMERR("%s: error deleting writeset tree clone", __func__);
1085                 dm_tm_unlock(md->tm, clone);
1086                 return r;
1087         }
1088
1089         r = dm_array_del(&md->era_array_info, le64_to_cpu(disk->era_array_root));
1090         if (r) {
1091                 DMERR("%s: error deleting era array clone", __func__);
1092                 dm_tm_unlock(md->tm, clone);
1093                 return r;
1094         }
1095
1096         location = dm_block_location(clone);
1097         dm_tm_unlock(md->tm, clone);
1098
1099         return dm_sm_dec_block(md->sm, location);
1100 }
1101
1102 struct metadata_stats {
1103         dm_block_t used;
1104         dm_block_t total;
1105         dm_block_t snap;
1106         uint32_t era;
1107 };
1108
1109 static int metadata_get_stats(struct era_metadata *md, void *ptr)
1110 {
1111         int r;
1112         struct metadata_stats *s = ptr;
1113         dm_block_t nr_free, nr_total;
1114
1115         r = dm_sm_get_nr_free(md->sm, &nr_free);
1116         if (r) {
1117                 DMERR("dm_sm_get_nr_free returned %d", r);
1118                 return r;
1119         }
1120
1121         r = dm_sm_get_nr_blocks(md->sm, &nr_total);
1122         if (r) {
1123                 DMERR("dm_pool_get_metadata_dev_size returned %d", r);
1124                 return r;
1125         }
1126
1127         s->used = nr_total - nr_free;
1128         s->total = nr_total;
1129         s->snap = md->metadata_snap;
1130         s->era = md->current_era;
1131
1132         return 0;
1133 }
1134
1135 /*----------------------------------------------------------------*/
1136
1137 struct era {
1138         struct dm_target *ti;
1139         struct dm_target_callbacks callbacks;
1140
1141         struct dm_dev *metadata_dev;
1142         struct dm_dev *origin_dev;
1143
1144         dm_block_t nr_blocks;
1145         uint32_t sectors_per_block;
1146         int sectors_per_block_shift;
1147         struct era_metadata *md;
1148
1149         struct workqueue_struct *wq;
1150         struct work_struct worker;
1151
1152         spinlock_t deferred_lock;
1153         struct bio_list deferred_bios;
1154
1155         spinlock_t rpc_lock;
1156         struct list_head rpc_calls;
1157
1158         struct digest digest;
1159         atomic_t suspended;
1160 };
1161
1162 struct rpc {
1163         struct list_head list;
1164
1165         int (*fn0)(struct era_metadata *);
1166         int (*fn1)(struct era_metadata *, void *);
1167         void *arg;
1168         int result;
1169
1170         struct completion complete;
1171 };
1172
1173 /*----------------------------------------------------------------
1174  * Remapping.
1175  *---------------------------------------------------------------*/
1176 static bool block_size_is_power_of_two(struct era *era)
1177 {
1178         return era->sectors_per_block_shift >= 0;
1179 }
1180
1181 static dm_block_t get_block(struct era *era, struct bio *bio)
1182 {
1183         sector_t block_nr = bio->bi_iter.bi_sector;
1184
1185         if (!block_size_is_power_of_two(era))
1186                 (void) sector_div(block_nr, era->sectors_per_block);
1187         else
1188                 block_nr >>= era->sectors_per_block_shift;
1189
1190         return block_nr;
1191 }
1192
1193 static void remap_to_origin(struct era *era, struct bio *bio)
1194 {
1195         bio_set_dev(bio, era->origin_dev->bdev);
1196 }
1197
1198 /*----------------------------------------------------------------
1199  * Worker thread
1200  *--------------------------------------------------------------*/
1201 static void wake_worker(struct era *era)
1202 {
1203         if (!atomic_read(&era->suspended))
1204                 queue_work(era->wq, &era->worker);
1205 }
1206
1207 static void process_old_eras(struct era *era)
1208 {
1209         int r;
1210
1211         if (!era->digest.step)
1212                 return;
1213
1214         r = era->digest.step(era->md, &era->digest);
1215         if (r < 0) {
1216                 DMERR("%s: digest step failed, stopping digestion", __func__);
1217                 era->digest.step = NULL;
1218
1219         } else if (era->digest.step)
1220                 wake_worker(era);
1221 }
1222
1223 static void process_deferred_bios(struct era *era)
1224 {
1225         int r;
1226         struct bio_list deferred_bios, marked_bios;
1227         struct bio *bio;
1228         bool commit_needed = false;
1229         bool failed = false;
1230
1231         bio_list_init(&deferred_bios);
1232         bio_list_init(&marked_bios);
1233
1234         spin_lock(&era->deferred_lock);
1235         bio_list_merge(&deferred_bios, &era->deferred_bios);
1236         bio_list_init(&era->deferred_bios);
1237         spin_unlock(&era->deferred_lock);
1238
1239         while ((bio = bio_list_pop(&deferred_bios))) {
1240                 r = writeset_test_and_set(&era->md->bitset_info,
1241                                           era->md->current_writeset,
1242                                           get_block(era, bio));
1243                 if (r < 0) {
1244                         /*
1245                          * This is bad news, we need to rollback.
1246                          * FIXME: finish.
1247                          */
1248                         failed = true;
1249
1250                 } else if (r == 0)
1251                         commit_needed = true;
1252
1253                 bio_list_add(&marked_bios, bio);
1254         }
1255
1256         if (commit_needed) {
1257                 r = metadata_commit(era->md);
1258                 if (r)
1259                         failed = true;
1260         }
1261
1262         if (failed)
1263                 while ((bio = bio_list_pop(&marked_bios)))
1264                         bio_io_error(bio);
1265         else
1266                 while ((bio = bio_list_pop(&marked_bios)))
1267                         generic_make_request(bio);
1268 }
1269
1270 static void process_rpc_calls(struct era *era)
1271 {
1272         int r;
1273         bool need_commit = false;
1274         struct list_head calls;
1275         struct rpc *rpc, *tmp;
1276
1277         INIT_LIST_HEAD(&calls);
1278         spin_lock(&era->rpc_lock);
1279         list_splice_init(&era->rpc_calls, &calls);
1280         spin_unlock(&era->rpc_lock);
1281
1282         list_for_each_entry_safe(rpc, tmp, &calls, list) {
1283                 rpc->result = rpc->fn0 ? rpc->fn0(era->md) : rpc->fn1(era->md, rpc->arg);
1284                 need_commit = true;
1285         }
1286
1287         if (need_commit) {
1288                 r = metadata_commit(era->md);
1289                 if (r)
1290                         list_for_each_entry_safe(rpc, tmp, &calls, list)
1291                                 rpc->result = r;
1292         }
1293
1294         list_for_each_entry_safe(rpc, tmp, &calls, list)
1295                 complete(&rpc->complete);
1296 }
1297
1298 static void kick_off_digest(struct era *era)
1299 {
1300         if (era->md->archived_writesets) {
1301                 era->md->archived_writesets = false;
1302                 metadata_digest_start(era->md, &era->digest);
1303         }
1304 }
1305
1306 static void do_work(struct work_struct *ws)
1307 {
1308         struct era *era = container_of(ws, struct era, worker);
1309
1310         kick_off_digest(era);
1311         process_old_eras(era);
1312         process_deferred_bios(era);
1313         process_rpc_calls(era);
1314 }
1315
1316 static void defer_bio(struct era *era, struct bio *bio)
1317 {
1318         spin_lock(&era->deferred_lock);
1319         bio_list_add(&era->deferred_bios, bio);
1320         spin_unlock(&era->deferred_lock);
1321
1322         wake_worker(era);
1323 }
1324
1325 /*
1326  * Make an rpc call to the worker to change the metadata.
1327  */
1328 static int perform_rpc(struct era *era, struct rpc *rpc)
1329 {
1330         rpc->result = 0;
1331         init_completion(&rpc->complete);
1332
1333         spin_lock(&era->rpc_lock);
1334         list_add(&rpc->list, &era->rpc_calls);
1335         spin_unlock(&era->rpc_lock);
1336
1337         wake_worker(era);
1338         wait_for_completion(&rpc->complete);
1339
1340         return rpc->result;
1341 }
1342
1343 static int in_worker0(struct era *era, int (*fn)(struct era_metadata *))
1344 {
1345         struct rpc rpc;
1346         rpc.fn0 = fn;
1347         rpc.fn1 = NULL;
1348
1349         return perform_rpc(era, &rpc);
1350 }
1351
1352 static int in_worker1(struct era *era,
1353                       int (*fn)(struct era_metadata *, void *), void *arg)
1354 {
1355         struct rpc rpc;
1356         rpc.fn0 = NULL;
1357         rpc.fn1 = fn;
1358         rpc.arg = arg;
1359
1360         return perform_rpc(era, &rpc);
1361 }
1362
1363 static void start_worker(struct era *era)
1364 {
1365         atomic_set(&era->suspended, 0);
1366 }
1367
1368 static void stop_worker(struct era *era)
1369 {
1370         atomic_set(&era->suspended, 1);
1371         flush_workqueue(era->wq);
1372 }
1373
1374 /*----------------------------------------------------------------
1375  * Target methods
1376  *--------------------------------------------------------------*/
1377 static int dev_is_congested(struct dm_dev *dev, int bdi_bits)
1378 {
1379         struct request_queue *q = bdev_get_queue(dev->bdev);
1380         return bdi_congested(q->backing_dev_info, bdi_bits);
1381 }
1382
1383 static int era_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1384 {
1385         struct era *era = container_of(cb, struct era, callbacks);
1386         return dev_is_congested(era->origin_dev, bdi_bits);
1387 }
1388
1389 static void era_destroy(struct era *era)
1390 {
1391         if (era->md)
1392                 metadata_close(era->md);
1393
1394         if (era->wq)
1395                 destroy_workqueue(era->wq);
1396
1397         if (era->origin_dev)
1398                 dm_put_device(era->ti, era->origin_dev);
1399
1400         if (era->metadata_dev)
1401                 dm_put_device(era->ti, era->metadata_dev);
1402
1403         kfree(era);
1404 }
1405
1406 static dm_block_t calc_nr_blocks(struct era *era)
1407 {
1408         return dm_sector_div_up(era->ti->len, era->sectors_per_block);
1409 }
1410
1411 static bool valid_block_size(dm_block_t block_size)
1412 {
1413         bool greater_than_zero = block_size > 0;
1414         bool multiple_of_min_block_size = (block_size & (MIN_BLOCK_SIZE - 1)) == 0;
1415
1416         return greater_than_zero && multiple_of_min_block_size;
1417 }
1418
1419 /*
1420  * <metadata dev> <data dev> <data block size (sectors)>
1421  */
1422 static int era_ctr(struct dm_target *ti, unsigned argc, char **argv)
1423 {
1424         int r;
1425         char dummy;
1426         struct era *era;
1427         struct era_metadata *md;
1428
1429         if (argc != 3) {
1430                 ti->error = "Invalid argument count";
1431                 return -EINVAL;
1432         }
1433
1434         era = kzalloc(sizeof(*era), GFP_KERNEL);
1435         if (!era) {
1436                 ti->error = "Error allocating era structure";
1437                 return -ENOMEM;
1438         }
1439
1440         era->ti = ti;
1441
1442         r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &era->metadata_dev);
1443         if (r) {
1444                 ti->error = "Error opening metadata device";
1445                 era_destroy(era);
1446                 return -EINVAL;
1447         }
1448
1449         r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &era->origin_dev);
1450         if (r) {
1451                 ti->error = "Error opening data device";
1452                 era_destroy(era);
1453                 return -EINVAL;
1454         }
1455
1456         r = sscanf(argv[2], "%u%c", &era->sectors_per_block, &dummy);
1457         if (r != 1) {
1458                 ti->error = "Error parsing block size";
1459                 era_destroy(era);
1460                 return -EINVAL;
1461         }
1462
1463         r = dm_set_target_max_io_len(ti, era->sectors_per_block);
1464         if (r) {
1465                 ti->error = "could not set max io len";
1466                 era_destroy(era);
1467                 return -EINVAL;
1468         }
1469
1470         if (!valid_block_size(era->sectors_per_block)) {
1471                 ti->error = "Invalid block size";
1472                 era_destroy(era);
1473                 return -EINVAL;
1474         }
1475         if (era->sectors_per_block & (era->sectors_per_block - 1))
1476                 era->sectors_per_block_shift = -1;
1477         else
1478                 era->sectors_per_block_shift = __ffs(era->sectors_per_block);
1479
1480         md = metadata_open(era->metadata_dev->bdev, era->sectors_per_block, true);
1481         if (IS_ERR(md)) {
1482                 ti->error = "Error reading metadata";
1483                 era_destroy(era);
1484                 return PTR_ERR(md);
1485         }
1486         era->md = md;
1487
1488         era->nr_blocks = calc_nr_blocks(era);
1489
1490         r = metadata_resize(era->md, &era->nr_blocks);
1491         if (r) {
1492                 ti->error = "couldn't resize metadata";
1493                 era_destroy(era);
1494                 return -ENOMEM;
1495         }
1496
1497         era->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1498         if (!era->wq) {
1499                 ti->error = "could not create workqueue for metadata object";
1500                 era_destroy(era);
1501                 return -ENOMEM;
1502         }
1503         INIT_WORK(&era->worker, do_work);
1504
1505         spin_lock_init(&era->deferred_lock);
1506         bio_list_init(&era->deferred_bios);
1507
1508         spin_lock_init(&era->rpc_lock);
1509         INIT_LIST_HEAD(&era->rpc_calls);
1510
1511         ti->private = era;
1512         ti->num_flush_bios = 1;
1513         ti->flush_supported = true;
1514
1515         ti->num_discard_bios = 1;
1516         era->callbacks.congested_fn = era_is_congested;
1517         dm_table_add_target_callbacks(ti->table, &era->callbacks);
1518
1519         return 0;
1520 }
1521
1522 static void era_dtr(struct dm_target *ti)
1523 {
1524         era_destroy(ti->private);
1525 }
1526
1527 static int era_map(struct dm_target *ti, struct bio *bio)
1528 {
1529         struct era *era = ti->private;
1530         dm_block_t block = get_block(era, bio);
1531
1532         /*
1533          * All bios get remapped to the origin device.  We do this now, but
1534          * it may not get issued until later.  Depending on whether the
1535          * block is marked in this era.
1536          */
1537         remap_to_origin(era, bio);
1538
1539         /*
1540          * REQ_PREFLUSH bios carry no data, so we're not interested in them.
1541          */
1542         if (!(bio->bi_opf & REQ_PREFLUSH) &&
1543             (bio_data_dir(bio) == WRITE) &&
1544             !metadata_current_marked(era->md, block)) {
1545                 defer_bio(era, bio);
1546                 return DM_MAPIO_SUBMITTED;
1547         }
1548
1549         return DM_MAPIO_REMAPPED;
1550 }
1551
1552 static void era_postsuspend(struct dm_target *ti)
1553 {
1554         int r;
1555         struct era *era = ti->private;
1556
1557         r = in_worker0(era, metadata_era_archive);
1558         if (r) {
1559                 DMERR("%s: couldn't archive current era", __func__);
1560                 /* FIXME: fail mode */
1561         }
1562
1563         stop_worker(era);
1564 }
1565
1566 static int era_preresume(struct dm_target *ti)
1567 {
1568         int r;
1569         struct era *era = ti->private;
1570         dm_block_t new_size = calc_nr_blocks(era);
1571
1572         if (era->nr_blocks != new_size) {
1573                 r = in_worker1(era, metadata_resize, &new_size);
1574                 if (r)
1575                         return r;
1576
1577                 era->nr_blocks = new_size;
1578         }
1579
1580         start_worker(era);
1581
1582         r = in_worker0(era, metadata_new_era);
1583         if (r) {
1584                 DMERR("%s: metadata_era_rollover failed", __func__);
1585                 return r;
1586         }
1587
1588         return 0;
1589 }
1590
1591 /*
1592  * Status format:
1593  *
1594  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
1595  * <current era> <held metadata root | '-'>
1596  */
1597 static void era_status(struct dm_target *ti, status_type_t type,
1598                        unsigned status_flags, char *result, unsigned maxlen)
1599 {
1600         int r;
1601         struct era *era = ti->private;
1602         ssize_t sz = 0;
1603         struct metadata_stats stats;
1604         char buf[BDEVNAME_SIZE];
1605
1606         switch (type) {
1607         case STATUSTYPE_INFO:
1608                 r = in_worker1(era, metadata_get_stats, &stats);
1609                 if (r)
1610                         goto err;
1611
1612                 DMEMIT("%u %llu/%llu %u",
1613                        (unsigned) (DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
1614                        (unsigned long long) stats.used,
1615                        (unsigned long long) stats.total,
1616                        (unsigned) stats.era);
1617
1618                 if (stats.snap != SUPERBLOCK_LOCATION)
1619                         DMEMIT(" %llu", stats.snap);
1620                 else
1621                         DMEMIT(" -");
1622                 break;
1623
1624         case STATUSTYPE_TABLE:
1625                 format_dev_t(buf, era->metadata_dev->bdev->bd_dev);
1626                 DMEMIT("%s ", buf);
1627                 format_dev_t(buf, era->origin_dev->bdev->bd_dev);
1628                 DMEMIT("%s %u", buf, era->sectors_per_block);
1629                 break;
1630         }
1631
1632         return;
1633
1634 err:
1635         DMEMIT("Error");
1636 }
1637
1638 static int era_message(struct dm_target *ti, unsigned argc, char **argv,
1639                        char *result, unsigned maxlen)
1640 {
1641         struct era *era = ti->private;
1642
1643         if (argc != 1) {
1644                 DMERR("incorrect number of message arguments");
1645                 return -EINVAL;
1646         }
1647
1648         if (!strcasecmp(argv[0], "checkpoint"))
1649                 return in_worker0(era, metadata_checkpoint);
1650
1651         if (!strcasecmp(argv[0], "take_metadata_snap"))
1652                 return in_worker0(era, metadata_take_snap);
1653
1654         if (!strcasecmp(argv[0], "drop_metadata_snap"))
1655                 return in_worker0(era, metadata_drop_snap);
1656
1657         DMERR("unsupported message '%s'", argv[0]);
1658         return -EINVAL;
1659 }
1660
1661 static sector_t get_dev_size(struct dm_dev *dev)
1662 {
1663         return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1664 }
1665
1666 static int era_iterate_devices(struct dm_target *ti,
1667                                iterate_devices_callout_fn fn, void *data)
1668 {
1669         struct era *era = ti->private;
1670         return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
1671 }
1672
1673 static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
1674 {
1675         struct era *era = ti->private;
1676         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
1677
1678         /*
1679          * If the system-determined stacked limits are compatible with the
1680          * era device's blocksize (io_opt is a factor) do not override them.
1681          */
1682         if (io_opt_sectors < era->sectors_per_block ||
1683             do_div(io_opt_sectors, era->sectors_per_block)) {
1684                 blk_limits_io_min(limits, 0);
1685                 blk_limits_io_opt(limits, era->sectors_per_block << SECTOR_SHIFT);
1686         }
1687 }
1688
1689 /*----------------------------------------------------------------*/
1690
1691 static struct target_type era_target = {
1692         .name = "era",
1693         .version = {1, 0, 0},
1694         .module = THIS_MODULE,
1695         .ctr = era_ctr,
1696         .dtr = era_dtr,
1697         .map = era_map,
1698         .postsuspend = era_postsuspend,
1699         .preresume = era_preresume,
1700         .status = era_status,
1701         .message = era_message,
1702         .iterate_devices = era_iterate_devices,
1703         .io_hints = era_io_hints
1704 };
1705
1706 static int __init dm_era_init(void)
1707 {
1708         int r;
1709
1710         r = dm_register_target(&era_target);
1711         if (r) {
1712                 DMERR("era target registration failed: %d", r);
1713                 return r;
1714         }
1715
1716         return 0;
1717 }
1718
1719 static void __exit dm_era_exit(void)
1720 {
1721         dm_unregister_target(&era_target);
1722 }
1723
1724 module_init(dm_era_init);
1725 module_exit(dm_era_exit);
1726
1727 MODULE_DESCRIPTION(DM_NAME " era target");
1728 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
1729 MODULE_LICENSE("GPL");