drivers/md/dm-era-target.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include "dm.h"
   3 #include "persistent-data/dm-transaction-manager.h"
   4 #include "persistent-data/dm-bitset.h"
   5 #include "persistent-data/dm-space-map.h"
   6
   7 #include <linux/dm-io.h>
   8 #include <linux/dm-kcopyd.h>
   9 #include <linux/init.h>
  10 #include <linux/mempool.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/vmalloc.h>
  14
  15 #define DM_MSG_PREFIX "era"
  16
  17 #define SUPERBLOCK_LOCATION 0
  18 #define SUPERBLOCK_MAGIC 2126579579
  19 #define SUPERBLOCK_CSUM_XOR 146538381
  20 #define MIN_ERA_VERSION 1
  21 #define MAX_ERA_VERSION 1
  22 #define INVALID_WRITESET_ROOT SUPERBLOCK_LOCATION
  23 #define MIN_BLOCK_SIZE 8
  24
  25 /*
  26  *--------------------------------------------------------------
  27  * Writeset
  28  *--------------------------------------------------------------
  29  */
  30 struct writeset_metadata {
  31         uint32_t nr_bits;
  32         dm_block_t root;
  33 };
  34
  35 struct writeset {
  36         struct writeset_metadata md;
  37
  38         /*
  39          * An in core copy of the bits to save constantly doing look ups on
  40          * disk.
  41          */
  42         unsigned long *bits;
  43 };
  44
  45 /*
  46  * This does not free off the on disk bitset as this will normally be done
  47  * after digesting into the era array.
  48  */
  49 static void writeset_free(struct writeset *ws)
  50 {
  51         vfree(ws->bits);
  52         ws->bits = NULL;
  53 }
  54
  55 static int setup_on_disk_bitset(struct dm_disk_bitset *info,
  56                                 unsigned int nr_bits, dm_block_t *root)
  57 {
  58         int r;
  59
  60         r = dm_bitset_empty(info, root);
  61         if (r)
  62                 return r;
  63
  64         return dm_bitset_resize(info, *root, 0, nr_bits, false, root);
  65 }
  66
  67 static size_t bitset_size(unsigned int nr_bits)
  68 {
  69         return sizeof(unsigned long) * dm_div_up(nr_bits, BITS_PER_LONG);
  70 }
  71
  72 /*
  73  * Allocates memory for the in core bitset.
  74  */
  75 static int writeset_alloc(struct writeset *ws, dm_block_t nr_blocks)
  76 {
  77         ws->bits = vzalloc(bitset_size(nr_blocks));
  78         if (!ws->bits) {
  79                 DMERR("%s: couldn't allocate in memory bitset", __func__);
  80                 return -ENOMEM;
  81         }
  82
  83         return 0;
  84 }
  85
  86 /*
  87  * Wipes the in-core bitset, and creates a new on disk bitset.
  88  */
  89 static int writeset_init(struct dm_disk_bitset *info, struct writeset *ws,
  90                          dm_block_t nr_blocks)
  91 {
  92         int r;
  93
  94         memset(ws->bits, 0, bitset_size(nr_blocks));
  95
  96         ws->md.nr_bits = nr_blocks;
  97         r = setup_on_disk_bitset(info, ws->md.nr_bits, &ws->md.root);
  98         if (r) {
  99                 DMERR("%s: setup_on_disk_bitset failed", __func__);
 100                 return r;
 101         }
 102
 103         return 0;
 104 }
 105
 106 static bool writeset_marked(struct writeset *ws, dm_block_t block)
 107 {
 108         return test_bit(block, ws->bits);
 109 }
 110
 111 static int writeset_marked_on_disk(struct dm_disk_bitset *info,
 112                                    struct writeset_metadata *m, dm_block_t block,
 113                                    bool *result)
 114 {
 115         int r;
 116         dm_block_t old = m->root;
 117
 118         /*
 119          * The bitset was flushed when it was archived, so we know there'll
 120          * be no change to the root.
 121          */
 122         r = dm_bitset_test_bit(info, m->root, block, &m->root, result);
 123         if (r) {
 124                 DMERR("%s: dm_bitset_test_bit failed", __func__);
 125                 return r;
 126         }
 127
 128         BUG_ON(m->root != old);
 129
 130         return r;
 131 }
 132
 133 /*
 134  * Returns < 0 on error, 0 if the bit wasn't previously set, 1 if it was.
 135  */
 136 static int writeset_test_and_set(struct dm_disk_bitset *info,
 137                                  struct writeset *ws, uint32_t block)
 138 {
 139         int r;
 140
 141         if (!test_bit(block, ws->bits)) {
 142                 r = dm_bitset_set_bit(info, ws->md.root, block, &ws->md.root);
 143                 if (r) {
 144                         /* FIXME: fail mode */
 145                         return r;
 146                 }
 147
 148                 return 0;
 149         }
 150
 151         return 1;
 152 }
 153
 154 /*
 155  *--------------------------------------------------------------
 156  * On disk metadata layout
 157  *--------------------------------------------------------------
 158  */
 159 #define SPACE_MAP_ROOT_SIZE 128
 160 #define UUID_LEN 16
 161
 162 struct writeset_disk {
 163         __le32 nr_bits;
 164         __le64 root;
 165 } __packed;
 166
 167 struct superblock_disk {
 168         __le32 csum;
 169         __le32 flags;
 170         __le64 blocknr;
 171
 172         __u8 uuid[UUID_LEN];
 173         __le64 magic;
 174         __le32 version;
 175
 176         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 177
 178         __le32 data_block_size;
 179         __le32 metadata_block_size;
 180         __le32 nr_blocks;
 181
 182         __le32 current_era;
 183         struct writeset_disk current_writeset;
 184
 185         /*
 186          * Only these two fields are valid within the metadata snapshot.
 187          */
 188         __le64 writeset_tree_root;
 189         __le64 era_array_root;
 190
 191         __le64 metadata_snap;
 192 } __packed;
 193
 194 /*
 195  *--------------------------------------------------------------
 196  * Superblock validation
 197  *--------------------------------------------------------------
 198  */
 199 static void sb_prepare_for_write(struct dm_block_validator *v,
 200                                  struct dm_block *b,
 201                                  size_t sb_block_size)
 202 {
 203         struct superblock_disk *disk = dm_block_data(b);
 204
 205         disk->blocknr = cpu_to_le64(dm_block_location(b));
 206         disk->csum = cpu_to_le32(dm_bm_checksum(&disk->flags,
 207                                                 sb_block_size - sizeof(__le32),
 208                                                 SUPERBLOCK_CSUM_XOR));
 209 }
 210
 211 static int check_metadata_version(struct superblock_disk *disk)
 212 {
 213         uint32_t metadata_version = le32_to_cpu(disk->version);
 214
 215         if (metadata_version < MIN_ERA_VERSION || metadata_version > MAX_ERA_VERSION) {
 216                 DMERR("Era metadata version %u found, but only versions between %u and %u supported.",
 217                       metadata_version, MIN_ERA_VERSION, MAX_ERA_VERSION);
 218                 return -EINVAL;
 219         }
 220
 221         return 0;
 222 }
 223
 224 static int sb_check(struct dm_block_validator *v,
 225                     struct dm_block *b,
 226                     size_t sb_block_size)
 227 {
 228         struct superblock_disk *disk = dm_block_data(b);
 229         __le32 csum_le;
 230
 231         if (dm_block_location(b) != le64_to_cpu(disk->blocknr)) {
 232                 DMERR("%s failed: blocknr %llu: wanted %llu",
 233                       __func__, le64_to_cpu(disk->blocknr),
 234                       (unsigned long long)dm_block_location(b));
 235                 return -ENOTBLK;
 236         }
 237
 238         if (le64_to_cpu(disk->magic) != SUPERBLOCK_MAGIC) {
 239                 DMERR("%s failed: magic %llu: wanted %llu",
 240                       __func__, le64_to_cpu(disk->magic),
 241                       (unsigned long long) SUPERBLOCK_MAGIC);
 242                 return -EILSEQ;
 243         }
 244
 245         csum_le = cpu_to_le32(dm_bm_checksum(&disk->flags,
 246                                              sb_block_size - sizeof(__le32),
 247                                              SUPERBLOCK_CSUM_XOR));
 248         if (csum_le != disk->csum) {
 249                 DMERR("%s failed: csum %u: wanted %u",
 250                       __func__, le32_to_cpu(csum_le), le32_to_cpu(disk->csum));
 251                 return -EILSEQ;
 252         }
 253
 254         return check_metadata_version(disk);
 255 }
 256
 257 static struct dm_block_validator sb_validator = {
 258         .name = "superblock",
 259         .prepare_for_write = sb_prepare_for_write,
 260         .check = sb_check
 261 };
 262
 263 /*
 264  *--------------------------------------------------------------
 265  * Low level metadata handling
 266  *--------------------------------------------------------------
 267  */
 268 #define DM_ERA_METADATA_BLOCK_SIZE 4096
 269 #define ERA_MAX_CONCURRENT_LOCKS 5
 270
 271 struct era_metadata {
 272         struct block_device *bdev;
 273         struct dm_block_manager *bm;
 274         struct dm_space_map *sm;
 275         struct dm_transaction_manager *tm;
 276
 277         dm_block_t block_size;
 278         uint32_t nr_blocks;
 279
 280         uint32_t current_era;
 281
 282         /*
 283          * We preallocate 2 writesets.  When an era rolls over we
 284          * switch between them. This means the allocation is done at
 285          * preresume time, rather than on the io path.
 286          */
 287         struct writeset writesets[2];
 288         struct writeset *current_writeset;
 289
 290         dm_block_t writeset_tree_root;
 291         dm_block_t era_array_root;
 292
 293         struct dm_disk_bitset bitset_info;
 294         struct dm_btree_info writeset_tree_info;
 295         struct dm_array_info era_array_info;
 296
 297         dm_block_t metadata_snap;
 298
 299         /*
 300          * A flag that is set whenever a writeset has been archived.
 301          */
 302         bool archived_writesets;
 303
 304         /*
 305          * Reading the space map root can fail, so we read it into this
 306          * buffer before the superblock is locked and updated.
 307          */
 308         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 309 };
 310
 311 static int superblock_read_lock(struct era_metadata *md,
 312                                 struct dm_block **sblock)
 313 {
 314         return dm_bm_read_lock(md->bm, SUPERBLOCK_LOCATION,
 315                                &sb_validator, sblock);
 316 }
 317
 318 static int superblock_lock_zero(struct era_metadata *md,
 319                                 struct dm_block **sblock)
 320 {
 321         return dm_bm_write_lock_zero(md->bm, SUPERBLOCK_LOCATION,
 322                                      &sb_validator, sblock);
 323 }
 324
 325 static int superblock_lock(struct era_metadata *md,
 326                            struct dm_block **sblock)
 327 {
 328         return dm_bm_write_lock(md->bm, SUPERBLOCK_LOCATION,
 329                                 &sb_validator, sblock);
 330 }
 331
 332 /* FIXME: duplication with cache and thin */
 333 static int superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 334 {
 335         int r;
 336         unsigned int i;
 337         struct dm_block *b;
 338         __le64 *data_le, zero = cpu_to_le64(0);
 339         unsigned int sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 340
 341         /*
 342          * We can't use a validator here - it may be all zeroes.
 343          */
 344         r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &b);
 345         if (r)
 346                 return r;
 347
 348         data_le = dm_block_data(b);
 349         *result = true;
 350         for (i = 0; i < sb_block_size; i++) {
 351                 if (data_le[i] != zero) {
 352                         *result = false;
 353                         break;
 354                 }
 355         }
 356
 357         dm_bm_unlock(b);
 358
 359         return 0;
 360 }
 361
 362 /*----------------------------------------------------------------*/
 363
 364 static void ws_pack(const struct writeset_metadata *core, struct writeset_disk *disk)
 365 {
 366         disk->nr_bits = cpu_to_le32(core->nr_bits);
 367         disk->root = cpu_to_le64(core->root);
 368 }
 369
 370 static void ws_unpack(const struct writeset_disk *disk, struct writeset_metadata *core)
 371 {
 372         core->nr_bits = le32_to_cpu(disk->nr_bits);
 373         core->root = le64_to_cpu(disk->root);
 374 }
 375
 376 static void ws_inc(void *context, const void *value, unsigned int count)
 377 {
 378         struct era_metadata *md = context;
 379         struct writeset_disk ws_d;
 380         dm_block_t b;
 381         unsigned int i;
 382
 383         for (i = 0; i < count; i++) {
 384                 memcpy(&ws_d, value + (i * sizeof(ws_d)), sizeof(ws_d));
 385                 b = le64_to_cpu(ws_d.root);
 386                 dm_tm_inc(md->tm, b);
 387         }
 388 }
 389
 390 static void ws_dec(void *context, const void *value, unsigned int count)
 391 {
 392         struct era_metadata *md = context;
 393         struct writeset_disk ws_d;
 394         dm_block_t b;
 395         unsigned int i;
 396
 397         for (i = 0; i < count; i++) {
 398                 memcpy(&ws_d, value + (i * sizeof(ws_d)), sizeof(ws_d));
 399                 b = le64_to_cpu(ws_d.root);
 400                 dm_bitset_del(&md->bitset_info, b);
 401         }
 402 }
 403
 404 static int ws_eq(void *context, const void *value1, const void *value2)
 405 {
 406         return !memcmp(value1, value2, sizeof(struct writeset_disk));
 407 }
 408
 409 /*----------------------------------------------------------------*/
 410
 411 static void setup_writeset_tree_info(struct era_metadata *md)
 412 {
 413         struct dm_btree_value_type *vt = &md->writeset_tree_info.value_type;
 414
 415         md->writeset_tree_info.tm = md->tm;
 416         md->writeset_tree_info.levels = 1;
 417         vt->context = md;
 418         vt->size = sizeof(struct writeset_disk);
 419         vt->inc = ws_inc;
 420         vt->dec = ws_dec;
 421         vt->equal = ws_eq;
 422 }
 423
 424 static void setup_era_array_info(struct era_metadata *md)
 425 {
 426         struct dm_btree_value_type vt;
 427
 428         vt.context = NULL;
 429         vt.size = sizeof(__le32);
 430         vt.inc = NULL;
 431         vt.dec = NULL;
 432         vt.equal = NULL;
 433
 434         dm_array_info_init(&md->era_array_info, md->tm, &vt);
 435 }
 436
 437 static void setup_infos(struct era_metadata *md)
 438 {
 439         dm_disk_bitset_init(md->tm, &md->bitset_info);
 440         setup_writeset_tree_info(md);
 441         setup_era_array_info(md);
 442 }
 443
 444 /*----------------------------------------------------------------*/
 445
 446 static int create_fresh_metadata(struct era_metadata *md)
 447 {
 448         int r;
 449
 450         r = dm_tm_create_with_sm(md->bm, SUPERBLOCK_LOCATION,
 451                                  &md->tm, &md->sm);
 452         if (r < 0) {
 453                 DMERR("dm_tm_create_with_sm failed");
 454                 return r;
 455         }
 456
 457         setup_infos(md);
 458
 459         r = dm_btree_empty(&md->writeset_tree_info, &md->writeset_tree_root);
 460         if (r) {
 461                 DMERR("couldn't create new writeset tree");
 462                 goto bad;
 463         }
 464
 465         r = dm_array_empty(&md->era_array_info, &md->era_array_root);
 466         if (r) {
 467                 DMERR("couldn't create era array");
 468                 goto bad;
 469         }
 470
 471         return 0;
 472
 473 bad:
 474         dm_sm_destroy(md->sm);
 475         dm_tm_destroy(md->tm);
 476
 477         return r;
 478 }
 479
 480 static int save_sm_root(struct era_metadata *md)
 481 {
 482         int r;
 483         size_t metadata_len;
 484
 485         r = dm_sm_root_size(md->sm, &metadata_len);
 486         if (r < 0)
 487                 return r;
 488
 489         return dm_sm_copy_root(md->sm, &md->metadata_space_map_root,
 490                                metadata_len);
 491 }
 492
 493 static void copy_sm_root(struct era_metadata *md, struct superblock_disk *disk)
 494 {
 495         memcpy(&disk->metadata_space_map_root,
 496                &md->metadata_space_map_root,
 497                sizeof(md->metadata_space_map_root));
 498 }
 499
 500 /*
 501  * Writes a superblock, including the static fields that don't get updated
 502  * with every commit (possible optimisation here).  'md' should be fully
 503  * constructed when this is called.
 504  */
 505 static void prepare_superblock(struct era_metadata *md, struct superblock_disk *disk)
 506 {
 507         disk->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
 508         disk->flags = cpu_to_le32(0ul);
 509
 510         /* FIXME: can't keep blanking the uuid (uuid is currently unused though) */
 511         memset(disk->uuid, 0, sizeof(disk->uuid));
 512         disk->version = cpu_to_le32(MAX_ERA_VERSION);
 513
 514         copy_sm_root(md, disk);
 515
 516         disk->data_block_size = cpu_to_le32(md->block_size);
 517         disk->metadata_block_size = cpu_to_le32(DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 518         disk->nr_blocks = cpu_to_le32(md->nr_blocks);
 519         disk->current_era = cpu_to_le32(md->current_era);
 520
 521         ws_pack(&md->current_writeset->md, &disk->current_writeset);
 522         disk->writeset_tree_root = cpu_to_le64(md->writeset_tree_root);
 523         disk->era_array_root = cpu_to_le64(md->era_array_root);
 524         disk->metadata_snap = cpu_to_le64(md->metadata_snap);
 525 }
 526
 527 static int write_superblock(struct era_metadata *md)
 528 {
 529         int r;
 530         struct dm_block *sblock;
 531         struct superblock_disk *disk;
 532
 533         r = save_sm_root(md);
 534         if (r) {
 535                 DMERR("%s: save_sm_root failed", __func__);
 536                 return r;
 537         }
 538
 539         r = superblock_lock_zero(md, &sblock);
 540         if (r)
 541                 return r;
 542
 543         disk = dm_block_data(sblock);
 544         prepare_superblock(md, disk);
 545
 546         return dm_tm_commit(md->tm, sblock);
 547 }
 548
 549 /*
 550  * Assumes block_size and the infos are set.
 551  */
 552 static int format_metadata(struct era_metadata *md)
 553 {
 554         int r;
 555
 556         r = create_fresh_metadata(md);
 557         if (r)
 558                 return r;
 559
 560         r = write_superblock(md);
 561         if (r) {
 562                 dm_sm_destroy(md->sm);
 563                 dm_tm_destroy(md->tm);
 564                 return r;
 565         }
 566
 567         return 0;
 568 }
 569
 570 static int open_metadata(struct era_metadata *md)
 571 {
 572         int r;
 573         struct dm_block *sblock;
 574         struct superblock_disk *disk;
 575
 576         r = superblock_read_lock(md, &sblock);
 577         if (r) {
 578                 DMERR("couldn't read_lock superblock");
 579                 return r;
 580         }
 581
 582         disk = dm_block_data(sblock);
 583
 584         /* Verify the data block size hasn't changed */
 585         if (le32_to_cpu(disk->data_block_size) != md->block_size) {
 586                 DMERR("changing the data block size (from %u to %llu) is not supported",
 587                       le32_to_cpu(disk->data_block_size), md->block_size);
 588                 r = -EINVAL;
 589                 goto bad;
 590         }
 591
 592         r = dm_tm_open_with_sm(md->bm, SUPERBLOCK_LOCATION,
 593                                disk->metadata_space_map_root,
 594                                sizeof(disk->metadata_space_map_root),
 595                                &md->tm, &md->sm);
 596         if (r) {
 597                 DMERR("dm_tm_open_with_sm failed");
 598                 goto bad;
 599         }
 600
 601         setup_infos(md);
 602
 603         md->nr_blocks = le32_to_cpu(disk->nr_blocks);
 604         md->current_era = le32_to_cpu(disk->current_era);
 605
 606         ws_unpack(&disk->current_writeset, &md->current_writeset->md);
 607         md->writeset_tree_root = le64_to_cpu(disk->writeset_tree_root);
 608         md->era_array_root = le64_to_cpu(disk->era_array_root);
 609         md->metadata_snap = le64_to_cpu(disk->metadata_snap);
 610         md->archived_writesets = true;
 611
 612         dm_bm_unlock(sblock);
 613
 614         return 0;
 615
 616 bad:
 617         dm_bm_unlock(sblock);
 618         return r;
 619 }
 620
 621 static int open_or_format_metadata(struct era_metadata *md,
 622                                    bool may_format)
 623 {
 624         int r;
 625         bool unformatted = false;
 626
 627         r = superblock_all_zeroes(md->bm, &unformatted);
 628         if (r)
 629                 return r;
 630
 631         if (unformatted)
 632                 return may_format ? format_metadata(md) : -EPERM;
 633
 634         return open_metadata(md);
 635 }
 636
 637 static int create_persistent_data_objects(struct era_metadata *md,
 638                                           bool may_format)
 639 {
 640         int r;
 641
 642         md->bm = dm_block_manager_create(md->bdev, DM_ERA_METADATA_BLOCK_SIZE,
 643                                          ERA_MAX_CONCURRENT_LOCKS);
 644         if (IS_ERR(md->bm)) {
 645                 DMERR("could not create block manager");
 646                 return PTR_ERR(md->bm);
 647         }
 648
 649         r = open_or_format_metadata(md, may_format);
 650         if (r)
 651                 dm_block_manager_destroy(md->bm);
 652
 653         return r;
 654 }
 655
 656 static void destroy_persistent_data_objects(struct era_metadata *md)
 657 {
 658         dm_sm_destroy(md->sm);
 659         dm_tm_destroy(md->tm);
 660         dm_block_manager_destroy(md->bm);
 661 }
 662
 663 /*
 664  * This waits until all era_map threads have picked up the new filter.
 665  */
 666 static void swap_writeset(struct era_metadata *md, struct writeset *new_writeset)
 667 {
 668         rcu_assign_pointer(md->current_writeset, new_writeset);
 669         synchronize_rcu();
 670 }
 671
 672 /*
 673  *------------------------------------------------------------------------
 674  * Writesets get 'digested' into the main era array.
 675  *
 676  * We're using a coroutine here so the worker thread can do the digestion,
 677  * thus avoiding synchronisation of the metadata.  Digesting a whole
 678  * writeset in one go would cause too much latency.
 679  *------------------------------------------------------------------------
 680  */
 681 struct digest {
 682         uint32_t era;
 683         unsigned int nr_bits, current_bit;
 684         struct writeset_metadata writeset;
 685         __le32 value;
 686         struct dm_disk_bitset info;
 687
 688         int (*step)(struct era_metadata *md, struct digest *d);
 689 };
 690
 691 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 692                                            struct digest *d);
 693
 694 static int metadata_digest_remove_writeset(struct era_metadata *md,
 695                                            struct digest *d)
 696 {
 697         int r;
 698         uint64_t key = d->era;
 699
 700         r = dm_btree_remove(&md->writeset_tree_info, md->writeset_tree_root,
 701                             &key, &md->writeset_tree_root);
 702         if (r) {
 703                 DMERR("%s: dm_btree_remove failed", __func__);
 704                 return r;
 705         }
 706
 707         d->step = metadata_digest_lookup_writeset;
 708         return 0;
 709 }
 710
 711 #define INSERTS_PER_STEP 100
 712
 713 static int metadata_digest_transcribe_writeset(struct era_metadata *md,
 714                                                struct digest *d)
 715 {
 716         int r;
 717         bool marked;
 718         unsigned int b, e = min(d->current_bit + INSERTS_PER_STEP, d->nr_bits);
 719
 720         for (b = d->current_bit; b < e; b++) {
 721                 r = writeset_marked_on_disk(&d->info, &d->writeset, b, &marked);
 722                 if (r) {
 723                         DMERR("%s: writeset_marked_on_disk failed", __func__);
 724                         return r;
 725                 }
 726
 727                 if (!marked)
 728                         continue;
 729
 730                 __dm_bless_for_disk(&d->value);
 731                 r = dm_array_set_value(&md->era_array_info, md->era_array_root,
 732                                        b, &d->value, &md->era_array_root);
 733                 if (r) {
 734                         DMERR("%s: dm_array_set_value failed", __func__);
 735                         return r;
 736                 }
 737         }
 738
 739         if (b == d->nr_bits)
 740                 d->step = metadata_digest_remove_writeset;
 741         else
 742                 d->current_bit = b;
 743
 744         return 0;
 745 }
 746
 747 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 748                                            struct digest *d)
 749 {
 750         int r;
 751         uint64_t key;
 752         struct writeset_disk disk;
 753
 754         r = dm_btree_find_lowest_key(&md->writeset_tree_info,
 755                                      md->writeset_tree_root, &key);
 756         if (r < 0)
 757                 return r;
 758
 759         d->era = key;
 760
 761         r = dm_btree_lookup(&md->writeset_tree_info,
 762                             md->writeset_tree_root, &key, &disk);
 763         if (r) {
 764                 if (r == -ENODATA) {
 765                         d->step = NULL;
 766                         return 0;
 767                 }
 768
 769                 DMERR("%s: dm_btree_lookup failed", __func__);
 770                 return r;
 771         }
 772
 773         ws_unpack(&disk, &d->writeset);
 774         d->value = cpu_to_le32(key);
 775
 776         /*
 777          * We initialise another bitset info to avoid any caching side effects
 778          * with the previous one.
 779          */
 780         dm_disk_bitset_init(md->tm, &d->info);
 781
 782         d->nr_bits = min(d->writeset.nr_bits, md->nr_blocks);
 783         d->current_bit = 0;
 784         d->step = metadata_digest_transcribe_writeset;
 785
 786         return 0;
 787 }
 788
 789 static int metadata_digest_start(struct era_metadata *md, struct digest *d)
 790 {
 791         if (d->step)
 792                 return 0;
 793
 794         memset(d, 0, sizeof(*d));
 795         d->step = metadata_digest_lookup_writeset;
 796
 797         return 0;
 798 }
 799
 800 /*
 801  *-----------------------------------------------------------------
 802  * High level metadata interface.  Target methods should use these,
 803  * and not the lower level ones.
 804  *-----------------------------------------------------------------
 805  */
 806 static struct era_metadata *metadata_open(struct block_device *bdev,
 807                                           sector_t block_size,
 808                                           bool may_format)
 809 {
 810         int r;
 811         struct era_metadata *md = kzalloc(sizeof(*md), GFP_KERNEL);
 812
 813         if (!md)
 814                 return NULL;
 815
 816         md->bdev = bdev;
 817         md->block_size = block_size;
 818
 819         md->writesets[0].md.root = INVALID_WRITESET_ROOT;
 820         md->writesets[1].md.root = INVALID_WRITESET_ROOT;
 821         md->current_writeset = &md->writesets[0];
 822
 823         r = create_persistent_data_objects(md, may_format);
 824         if (r) {
 825                 kfree(md);
 826                 return ERR_PTR(r);
 827         }
 828
 829         return md;
 830 }
 831
 832 static void metadata_close(struct era_metadata *md)
 833 {
 834         writeset_free(&md->writesets[0]);
 835         writeset_free(&md->writesets[1]);
 836         destroy_persistent_data_objects(md);
 837         kfree(md);
 838 }
 839
 840 static bool valid_nr_blocks(dm_block_t n)
 841 {
 842         /*
 843          * dm_bitset restricts us to 2^32.  test_bit & co. restrict us
 844          * further to 2^31 - 1
 845          */
 846         return n < (1ull << 31);
 847 }
 848
 849 static int metadata_resize(struct era_metadata *md, void *arg)
 850 {
 851         int r;
 852         dm_block_t *new_size = arg;
 853         __le32 value;
 854
 855         if (!valid_nr_blocks(*new_size)) {
 856                 DMERR("Invalid number of origin blocks %llu",
 857                       (unsigned long long) *new_size);
 858                 return -EINVAL;
 859         }
 860
 861         writeset_free(&md->writesets[0]);
 862         writeset_free(&md->writesets[1]);
 863
 864         r = writeset_alloc(&md->writesets[0], *new_size);
 865         if (r) {
 866                 DMERR("%s: writeset_alloc failed for writeset 0", __func__);
 867                 return r;
 868         }
 869
 870         r = writeset_alloc(&md->writesets[1], *new_size);
 871         if (r) {
 872                 DMERR("%s: writeset_alloc failed for writeset 1", __func__);
 873                 writeset_free(&md->writesets[0]);
 874                 return r;
 875         }
 876
 877         value = cpu_to_le32(0u);
 878         __dm_bless_for_disk(&value);
 879         r = dm_array_resize(&md->era_array_info, md->era_array_root,
 880                             md->nr_blocks, *new_size,
 881                             &value, &md->era_array_root);
 882         if (r) {
 883                 DMERR("%s: dm_array_resize failed", __func__);
 884                 writeset_free(&md->writesets[0]);
 885                 writeset_free(&md->writesets[1]);
 886                 return r;
 887         }
 888
 889         md->nr_blocks = *new_size;
 890         return 0;
 891 }
 892
 893 static int metadata_era_archive(struct era_metadata *md)
 894 {
 895         int r;
 896         uint64_t keys[1];
 897         struct writeset_disk value;
 898
 899         r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 900                             &md->current_writeset->md.root);
 901         if (r) {
 902                 DMERR("%s: dm_bitset_flush failed", __func__);
 903                 return r;
 904         }
 905
 906         ws_pack(&md->current_writeset->md, &value);
 907
 908         keys[0] = md->current_era;
 909         __dm_bless_for_disk(&value);
 910         r = dm_btree_insert(&md->writeset_tree_info, md->writeset_tree_root,
 911                             keys, &value, &md->writeset_tree_root);
 912         if (r) {
 913                 DMERR("%s: couldn't insert writeset into btree", __func__);
 914                 /* FIXME: fail mode */
 915                 return r;
 916         }
 917
 918         md->current_writeset->md.root = INVALID_WRITESET_ROOT;
 919         md->archived_writesets = true;
 920
 921         return 0;
 922 }
 923
 924 static struct writeset *next_writeset(struct era_metadata *md)
 925 {
 926         return (md->current_writeset == &md->writesets[0]) ?
 927                 &md->writesets[1] : &md->writesets[0];
 928 }
 929
 930 static int metadata_new_era(struct era_metadata *md)
 931 {
 932         int r;
 933         struct writeset *new_writeset = next_writeset(md);
 934
 935         r = writeset_init(&md->bitset_info, new_writeset, md->nr_blocks);
 936         if (r) {
 937                 DMERR("%s: writeset_init failed", __func__);
 938                 return r;
 939         }
 940
 941         swap_writeset(md, new_writeset);
 942         md->current_era++;
 943
 944         return 0;
 945 }
 946
 947 static int metadata_era_rollover(struct era_metadata *md)
 948 {
 949         int r;
 950
 951         if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 952                 r = metadata_era_archive(md);
 953                 if (r) {
 954                         DMERR("%s: metadata_archive_era failed", __func__);
 955                         /* FIXME: fail mode? */
 956                         return r;
 957                 }
 958         }
 959
 960         r = metadata_new_era(md);
 961         if (r) {
 962                 DMERR("%s: new era failed", __func__);
 963                 /* FIXME: fail mode */
 964                 return r;
 965         }
 966
 967         return 0;
 968 }
 969
 970 static bool metadata_current_marked(struct era_metadata *md, dm_block_t block)
 971 {
 972         bool r;
 973         struct writeset *ws;
 974
 975         rcu_read_lock();
 976         ws = rcu_dereference(md->current_writeset);
 977         r = writeset_marked(ws, block);
 978         rcu_read_unlock();
 979
 980         return r;
 981 }
 982
 983 static int metadata_commit(struct era_metadata *md)
 984 {
 985         int r;
 986         struct dm_block *sblock;
 987
 988         if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 989                 r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 990                                     &md->current_writeset->md.root);
 991                 if (r) {
 992                         DMERR("%s: bitset flush failed", __func__);
 993                         return r;
 994                 }
 995         }
 996
 997         r = dm_tm_pre_commit(md->tm);
 998         if (r) {
 999                 DMERR("%s: pre commit failed", __func__);
1000                 return r;
1001         }
1002
1003         r = save_sm_root(md);
1004         if (r) {
1005                 DMERR("%s: save_sm_root failed", __func__);
1006                 return r;
1007         }
1008
1009         r = superblock_lock(md, &sblock);
1010         if (r) {
1011                 DMERR("%s: superblock lock failed", __func__);
1012                 return r;
1013         }
1014
1015         prepare_superblock(md, dm_block_data(sblock));
1016
1017         return dm_tm_commit(md->tm, sblock);
1018 }
1019
1020 static int metadata_checkpoint(struct era_metadata *md)
1021 {
1022         /*
1023          * For now we just rollover, but later I want to put a check in to
1024          * avoid this if the filter is still pretty fresh.
1025          */
1026         return metadata_era_rollover(md);
1027 }
1028
1029 /*
1030  * Metadata snapshots allow userland to access era data.
1031  */
1032 static int metadata_take_snap(struct era_metadata *md)
1033 {
1034         int r, inc;
1035         struct dm_block *clone;
1036
1037         if (md->metadata_snap != SUPERBLOCK_LOCATION) {
1038                 DMERR("%s: metadata snapshot already exists", __func__);
1039                 return -EINVAL;
1040         }
1041
1042         r = metadata_era_rollover(md);
1043         if (r) {
1044                 DMERR("%s: era rollover failed", __func__);
1045                 return r;
1046         }
1047
1048         r = metadata_commit(md);
1049         if (r) {
1050                 DMERR("%s: pre commit failed", __func__);
1051                 return r;
1052         }
1053
1054         r = dm_sm_inc_block(md->sm, SUPERBLOCK_LOCATION);
1055         if (r) {
1056                 DMERR("%s: couldn't increment superblock", __func__);
1057                 return r;
1058         }
1059
1060         r = dm_tm_shadow_block(md->tm, SUPERBLOCK_LOCATION,
1061                                &sb_validator, &clone, &inc);
1062         if (r) {
1063                 DMERR("%s: couldn't shadow superblock", __func__);
1064                 dm_sm_dec_block(md->sm, SUPERBLOCK_LOCATION);
1065                 return r;
1066         }
1067         BUG_ON(!inc);
1068
1069         r = dm_sm_inc_block(md->sm, md->writeset_tree_root);
1070         if (r) {
1071                 DMERR("%s: couldn't inc writeset tree root", __func__);
1072                 dm_tm_unlock(md->tm, clone);
1073                 return r;
1074         }
1075
1076         r = dm_sm_inc_block(md->sm, md->era_array_root);
1077         if (r) {
1078                 DMERR("%s: couldn't inc era tree root", __func__);
1079                 dm_sm_dec_block(md->sm, md->writeset_tree_root);
1080                 dm_tm_unlock(md->tm, clone);
1081                 return r;
1082         }
1083
1084         md->metadata_snap = dm_block_location(clone);
1085
1086         dm_tm_unlock(md->tm, clone);
1087
1088         return 0;
1089 }
1090
1091 static int metadata_drop_snap(struct era_metadata *md)
1092 {
1093         int r;
1094         dm_block_t location;
1095         struct dm_block *clone;
1096         struct superblock_disk *disk;
1097
1098         if (md->metadata_snap == SUPERBLOCK_LOCATION) {
1099                 DMERR("%s: no snap to drop", __func__);
1100                 return -EINVAL;
1101         }
1102
1103         r = dm_tm_read_lock(md->tm, md->metadata_snap, &sb_validator, &clone);
1104         if (r) {
1105                 DMERR("%s: couldn't read lock superblock clone", __func__);
1106                 return r;
1107         }
1108
1109         /*
1110          * Whatever happens now we'll commit with no record of the metadata
1111          * snap.
1112          */
1113         md->metadata_snap = SUPERBLOCK_LOCATION;
1114
1115         disk = dm_block_data(clone);
1116         r = dm_btree_del(&md->writeset_tree_info,
1117                          le64_to_cpu(disk->writeset_tree_root));
1118         if (r) {
1119                 DMERR("%s: error deleting writeset tree clone", __func__);
1120                 dm_tm_unlock(md->tm, clone);
1121                 return r;
1122         }
1123
1124         r = dm_array_del(&md->era_array_info, le64_to_cpu(disk->era_array_root));
1125         if (r) {
1126                 DMERR("%s: error deleting era array clone", __func__);
1127                 dm_tm_unlock(md->tm, clone);
1128                 return r;
1129         }
1130
1131         location = dm_block_location(clone);
1132         dm_tm_unlock(md->tm, clone);
1133
1134         return dm_sm_dec_block(md->sm, location);
1135 }
1136
1137 struct metadata_stats {
1138         dm_block_t used;
1139         dm_block_t total;
1140         dm_block_t snap;
1141         uint32_t era;
1142 };
1143
1144 static int metadata_get_stats(struct era_metadata *md, void *ptr)
1145 {
1146         int r;
1147         struct metadata_stats *s = ptr;
1148         dm_block_t nr_free, nr_total;
1149
1150         r = dm_sm_get_nr_free(md->sm, &nr_free);
1151         if (r) {
1152                 DMERR("dm_sm_get_nr_free returned %d", r);
1153                 return r;
1154         }
1155
1156         r = dm_sm_get_nr_blocks(md->sm, &nr_total);
1157         if (r) {
1158                 DMERR("dm_pool_get_metadata_dev_size returned %d", r);
1159                 return r;
1160         }
1161
1162         s->used = nr_total - nr_free;
1163         s->total = nr_total;
1164         s->snap = md->metadata_snap;
1165         s->era = md->current_era;
1166
1167         return 0;
1168 }
1169
1170 /*----------------------------------------------------------------*/
1171
1172 struct era {
1173         struct dm_target *ti;
1174
1175         struct dm_dev *metadata_dev;
1176         struct dm_dev *origin_dev;
1177
1178         dm_block_t nr_blocks;
1179         uint32_t sectors_per_block;
1180         int sectors_per_block_shift;
1181         struct era_metadata *md;
1182
1183         struct workqueue_struct *wq;
1184         struct work_struct worker;
1185
1186         spinlock_t deferred_lock;
1187         struct bio_list deferred_bios;
1188
1189         spinlock_t rpc_lock;
1190         struct list_head rpc_calls;
1191
1192         struct digest digest;
1193         atomic_t suspended;
1194 };
1195
1196 struct rpc {
1197         struct list_head list;
1198
1199         int (*fn0)(struct era_metadata *md);
1200         int (*fn1)(struct era_metadata *md, void *ref);
1201         void *arg;
1202         int result;
1203
1204         struct completion complete;
1205 };
1206
1207 /*
1208  *---------------------------------------------------------------
1209  * Remapping.
1210  *---------------------------------------------------------------
1211  */
1212 static bool block_size_is_power_of_two(struct era *era)
1213 {
1214         return era->sectors_per_block_shift >= 0;
1215 }
1216
1217 static dm_block_t get_block(struct era *era, struct bio *bio)
1218 {
1219         sector_t block_nr = bio->bi_iter.bi_sector;
1220
1221         if (!block_size_is_power_of_two(era))
1222                 (void) sector_div(block_nr, era->sectors_per_block);
1223         else
1224                 block_nr >>= era->sectors_per_block_shift;
1225
1226         return block_nr;
1227 }
1228
1229 static void remap_to_origin(struct era *era, struct bio *bio)
1230 {
1231         bio_set_dev(bio, era->origin_dev->bdev);
1232 }
1233
1234 /*
1235  *--------------------------------------------------------------
1236  * Worker thread
1237  *--------------------------------------------------------------
1238  */
1239 static void wake_worker(struct era *era)
1240 {
1241         if (!atomic_read(&era->suspended))
1242                 queue_work(era->wq, &era->worker);
1243 }
1244
1245 static void process_old_eras(struct era *era)
1246 {
1247         int r;
1248
1249         if (!era->digest.step)
1250                 return;
1251
1252         r = era->digest.step(era->md, &era->digest);
1253         if (r < 0) {
1254                 DMERR("%s: digest step failed, stopping digestion", __func__);
1255                 era->digest.step = NULL;
1256
1257         } else if (era->digest.step)
1258                 wake_worker(era);
1259 }
1260
1261 static void process_deferred_bios(struct era *era)
1262 {
1263         int r;
1264         struct bio_list deferred_bios, marked_bios;
1265         struct bio *bio;
1266         struct blk_plug plug;
1267         bool commit_needed = false;
1268         bool failed = false;
1269         struct writeset *ws = era->md->current_writeset;
1270
1271         bio_list_init(&deferred_bios);
1272         bio_list_init(&marked_bios);
1273
1274         spin_lock(&era->deferred_lock);
1275         bio_list_merge(&deferred_bios, &era->deferred_bios);
1276         bio_list_init(&era->deferred_bios);
1277         spin_unlock(&era->deferred_lock);
1278
1279         if (bio_list_empty(&deferred_bios))
1280                 return;
1281
1282         while ((bio = bio_list_pop(&deferred_bios))) {
1283                 r = writeset_test_and_set(&era->md->bitset_info, ws,
1284                                           get_block(era, bio));
1285                 if (r < 0) {
1286                         /*
1287                          * This is bad news, we need to rollback.
1288                          * FIXME: finish.
1289                          */
1290                         failed = true;
1291                 } else if (r == 0)
1292                         commit_needed = true;
1293
1294                 bio_list_add(&marked_bios, bio);
1295         }
1296
1297         if (commit_needed) {
1298                 r = metadata_commit(era->md);
1299                 if (r)
1300                         failed = true;
1301         }
1302
1303         if (failed)
1304                 while ((bio = bio_list_pop(&marked_bios)))
1305                         bio_io_error(bio);
1306         else {
1307                 blk_start_plug(&plug);
1308                 while ((bio = bio_list_pop(&marked_bios))) {
1309                         /*
1310                          * Only update the in-core writeset if the on-disk one
1311                          * was updated too.
1312                          */
1313                         if (commit_needed)
1314                                 set_bit(get_block(era, bio), ws->bits);
1315                         submit_bio_noacct(bio);
1316                 }
1317                 blk_finish_plug(&plug);
1318         }
1319 }
1320
1321 static void process_rpc_calls(struct era *era)
1322 {
1323         int r;
1324         bool need_commit = false;
1325         struct list_head calls;
1326         struct rpc *rpc, *tmp;
1327
1328         INIT_LIST_HEAD(&calls);
1329         spin_lock(&era->rpc_lock);
1330         list_splice_init(&era->rpc_calls, &calls);
1331         spin_unlock(&era->rpc_lock);
1332
1333         list_for_each_entry_safe(rpc, tmp, &calls, list) {
1334                 rpc->result = rpc->fn0 ? rpc->fn0(era->md) : rpc->fn1(era->md, rpc->arg);
1335                 need_commit = true;
1336         }
1337
1338         if (need_commit) {
1339                 r = metadata_commit(era->md);
1340                 if (r)
1341                         list_for_each_entry_safe(rpc, tmp, &calls, list)
1342                                 rpc->result = r;
1343         }
1344
1345         list_for_each_entry_safe(rpc, tmp, &calls, list)
1346                 complete(&rpc->complete);
1347 }
1348
1349 static void kick_off_digest(struct era *era)
1350 {
1351         if (era->md->archived_writesets) {
1352                 era->md->archived_writesets = false;
1353                 metadata_digest_start(era->md, &era->digest);
1354         }
1355 }
1356
1357 static void do_work(struct work_struct *ws)
1358 {
1359         struct era *era = container_of(ws, struct era, worker);
1360
1361         kick_off_digest(era);
1362         process_old_eras(era);
1363         process_deferred_bios(era);
1364         process_rpc_calls(era);
1365 }
1366
1367 static void defer_bio(struct era *era, struct bio *bio)
1368 {
1369         spin_lock(&era->deferred_lock);
1370         bio_list_add(&era->deferred_bios, bio);
1371         spin_unlock(&era->deferred_lock);
1372
1373         wake_worker(era);
1374 }
1375
1376 /*
1377  * Make an rpc call to the worker to change the metadata.
1378  */
1379 static int perform_rpc(struct era *era, struct rpc *rpc)
1380 {
1381         rpc->result = 0;
1382         init_completion(&rpc->complete);
1383
1384         spin_lock(&era->rpc_lock);
1385         list_add(&rpc->list, &era->rpc_calls);
1386         spin_unlock(&era->rpc_lock);
1387
1388         wake_worker(era);
1389         wait_for_completion(&rpc->complete);
1390
1391         return rpc->result;
1392 }
1393
1394 static int in_worker0(struct era *era, int (*fn)(struct era_metadata *md))
1395 {
1396         struct rpc rpc;
1397
1398         rpc.fn0 = fn;
1399         rpc.fn1 = NULL;
1400
1401         return perform_rpc(era, &rpc);
1402 }
1403
1404 static int in_worker1(struct era *era,
1405                       int (*fn)(struct era_metadata *md, void *ref), void *arg)
1406 {
1407         struct rpc rpc;
1408
1409         rpc.fn0 = NULL;
1410         rpc.fn1 = fn;
1411         rpc.arg = arg;
1412
1413         return perform_rpc(era, &rpc);
1414 }
1415
1416 static void start_worker(struct era *era)
1417 {
1418         atomic_set(&era->suspended, 0);
1419 }
1420
1421 static void stop_worker(struct era *era)
1422 {
1423         atomic_set(&era->suspended, 1);
1424         drain_workqueue(era->wq);
1425 }
1426
1427 /*
1428  *--------------------------------------------------------------
1429  * Target methods
1430  *--------------------------------------------------------------
1431  */
1432 static void era_destroy(struct era *era)
1433 {
1434         if (era->md)
1435                 metadata_close(era->md);
1436
1437         if (era->wq)
1438                 destroy_workqueue(era->wq);
1439
1440         if (era->origin_dev)
1441                 dm_put_device(era->ti, era->origin_dev);
1442
1443         if (era->metadata_dev)
1444                 dm_put_device(era->ti, era->metadata_dev);
1445
1446         kfree(era);
1447 }
1448
1449 static dm_block_t calc_nr_blocks(struct era *era)
1450 {
1451         return dm_sector_div_up(era->ti->len, era->sectors_per_block);
1452 }
1453
1454 static bool valid_block_size(dm_block_t block_size)
1455 {
1456         bool greater_than_zero = block_size > 0;
1457         bool multiple_of_min_block_size = (block_size & (MIN_BLOCK_SIZE - 1)) == 0;
1458
1459         return greater_than_zero && multiple_of_min_block_size;
1460 }
1461
1462 /*
1463  * <metadata dev> <data dev> <data block size (sectors)>
1464  */
1465 static int era_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1466 {
1467         int r;
1468         char dummy;
1469         struct era *era;
1470         struct era_metadata *md;
1471
1472         if (argc != 3) {
1473                 ti->error = "Invalid argument count";
1474                 return -EINVAL;
1475         }
1476
1477         era = kzalloc(sizeof(*era), GFP_KERNEL);
1478         if (!era) {
1479                 ti->error = "Error allocating era structure";
1480                 return -ENOMEM;
1481         }
1482
1483         era->ti = ti;
1484
1485         r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &era->metadata_dev);
1486         if (r) {
1487                 ti->error = "Error opening metadata device";
1488                 era_destroy(era);
1489                 return -EINVAL;
1490         }
1491
1492         r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &era->origin_dev);
1493         if (r) {
1494                 ti->error = "Error opening data device";
1495                 era_destroy(era);
1496                 return -EINVAL;
1497         }
1498
1499         r = sscanf(argv[2], "%u%c", &era->sectors_per_block, &dummy);
1500         if (r != 1) {
1501                 ti->error = "Error parsing block size";
1502                 era_destroy(era);
1503                 return -EINVAL;
1504         }
1505
1506         r = dm_set_target_max_io_len(ti, era->sectors_per_block);
1507         if (r) {
1508                 ti->error = "could not set max io len";
1509                 era_destroy(era);
1510                 return -EINVAL;
1511         }
1512
1513         if (!valid_block_size(era->sectors_per_block)) {
1514                 ti->error = "Invalid block size";
1515                 era_destroy(era);
1516                 return -EINVAL;
1517         }
1518         if (era->sectors_per_block & (era->sectors_per_block - 1))
1519                 era->sectors_per_block_shift = -1;
1520         else
1521                 era->sectors_per_block_shift = __ffs(era->sectors_per_block);
1522
1523         md = metadata_open(era->metadata_dev->bdev, era->sectors_per_block, true);
1524         if (IS_ERR(md)) {
1525                 ti->error = "Error reading metadata";
1526                 era_destroy(era);
1527                 return PTR_ERR(md);
1528         }
1529         era->md = md;
1530
1531         era->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1532         if (!era->wq) {
1533                 ti->error = "could not create workqueue for metadata object";
1534                 era_destroy(era);
1535                 return -ENOMEM;
1536         }
1537         INIT_WORK(&era->worker, do_work);
1538
1539         spin_lock_init(&era->deferred_lock);
1540         bio_list_init(&era->deferred_bios);
1541
1542         spin_lock_init(&era->rpc_lock);
1543         INIT_LIST_HEAD(&era->rpc_calls);
1544
1545         ti->private = era;
1546         ti->num_flush_bios = 1;
1547         ti->flush_supported = true;
1548
1549         ti->num_discard_bios = 1;
1550
1551         return 0;
1552 }
1553
1554 static void era_dtr(struct dm_target *ti)
1555 {
1556         era_destroy(ti->private);
1557 }
1558
1559 static int era_map(struct dm_target *ti, struct bio *bio)
1560 {
1561         struct era *era = ti->private;
1562         dm_block_t block = get_block(era, bio);
1563
1564         /*
1565          * All bios get remapped to the origin device.  We do this now, but
1566          * it may not get issued until later.  Depending on whether the
1567          * block is marked in this era.
1568          */
1569         remap_to_origin(era, bio);
1570
1571         /*
1572          * REQ_PREFLUSH bios carry no data, so we're not interested in them.
1573          */
1574         if (!(bio->bi_opf & REQ_PREFLUSH) &&
1575             (bio_data_dir(bio) == WRITE) &&
1576             !metadata_current_marked(era->md, block)) {
1577                 defer_bio(era, bio);
1578                 return DM_MAPIO_SUBMITTED;
1579         }
1580
1581         return DM_MAPIO_REMAPPED;
1582 }
1583
1584 static void era_postsuspend(struct dm_target *ti)
1585 {
1586         int r;
1587         struct era *era = ti->private;
1588
1589         r = in_worker0(era, metadata_era_archive);
1590         if (r) {
1591                 DMERR("%s: couldn't archive current era", __func__);
1592                 /* FIXME: fail mode */
1593         }
1594
1595         stop_worker(era);
1596
1597         r = metadata_commit(era->md);
1598         if (r) {
1599                 DMERR("%s: metadata_commit failed", __func__);
1600                 /* FIXME: fail mode */
1601         }
1602 }
1603
1604 static int era_preresume(struct dm_target *ti)
1605 {
1606         int r;
1607         struct era *era = ti->private;
1608         dm_block_t new_size = calc_nr_blocks(era);
1609
1610         if (era->nr_blocks != new_size) {
1611                 r = metadata_resize(era->md, &new_size);
1612                 if (r) {
1613                         DMERR("%s: metadata_resize failed", __func__);
1614                         return r;
1615                 }
1616
1617                 r = metadata_commit(era->md);
1618                 if (r) {
1619                         DMERR("%s: metadata_commit failed", __func__);
1620                         return r;
1621                 }
1622
1623                 era->nr_blocks = new_size;
1624         }
1625
1626         start_worker(era);
1627
1628         r = in_worker0(era, metadata_era_rollover);
1629         if (r) {
1630                 DMERR("%s: metadata_era_rollover failed", __func__);
1631                 return r;
1632         }
1633
1634         return 0;
1635 }
1636
1637 /*
1638  * Status format:
1639  *
1640  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
1641  * <current era> <held metadata root | '-'>
1642  */
1643 static void era_status(struct dm_target *ti, status_type_t type,
1644                        unsigned int status_flags, char *result, unsigned int maxlen)
1645 {
1646         int r;
1647         struct era *era = ti->private;
1648         ssize_t sz = 0;
1649         struct metadata_stats stats;
1650         char buf[BDEVNAME_SIZE];
1651
1652         switch (type) {
1653         case STATUSTYPE_INFO:
1654                 r = in_worker1(era, metadata_get_stats, &stats);
1655                 if (r)
1656                         goto err;
1657
1658                 DMEMIT("%u %llu/%llu %u",
1659                        (unsigned int) (DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
1660                        (unsigned long long) stats.used,
1661                        (unsigned long long) stats.total,
1662                        (unsigned int) stats.era);
1663
1664                 if (stats.snap != SUPERBLOCK_LOCATION)
1665                         DMEMIT(" %llu", stats.snap);
1666                 else
1667                         DMEMIT(" -");
1668                 break;
1669
1670         case STATUSTYPE_TABLE:
1671                 format_dev_t(buf, era->metadata_dev->bdev->bd_dev);
1672                 DMEMIT("%s ", buf);
1673                 format_dev_t(buf, era->origin_dev->bdev->bd_dev);
1674                 DMEMIT("%s %u", buf, era->sectors_per_block);
1675                 break;
1676
1677         case STATUSTYPE_IMA:
1678                 *result = '\0';
1679                 break;
1680         }
1681
1682         return;
1683
1684 err:
1685         DMEMIT("Error");
1686 }
1687
1688 static int era_message(struct dm_target *ti, unsigned int argc, char **argv,
1689                        char *result, unsigned int maxlen)
1690 {
1691         struct era *era = ti->private;
1692
1693         if (argc != 1) {
1694                 DMERR("incorrect number of message arguments");
1695                 return -EINVAL;
1696         }
1697
1698         if (!strcasecmp(argv[0], "checkpoint"))
1699                 return in_worker0(era, metadata_checkpoint);
1700
1701         if (!strcasecmp(argv[0], "take_metadata_snap"))
1702                 return in_worker0(era, metadata_take_snap);
1703
1704         if (!strcasecmp(argv[0], "drop_metadata_snap"))
1705                 return in_worker0(era, metadata_drop_snap);
1706
1707         DMERR("unsupported message '%s'", argv[0]);
1708         return -EINVAL;
1709 }
1710
1711 static sector_t get_dev_size(struct dm_dev *dev)
1712 {
1713         return bdev_nr_sectors(dev->bdev);
1714 }
1715
1716 static int era_iterate_devices(struct dm_target *ti,
1717                                iterate_devices_callout_fn fn, void *data)
1718 {
1719         struct era *era = ti->private;
1720
1721         return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
1722 }
1723
1724 static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
1725 {
1726         struct era *era = ti->private;
1727         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
1728
1729         /*
1730          * If the system-determined stacked limits are compatible with the
1731          * era device's blocksize (io_opt is a factor) do not override them.
1732          */
1733         if (io_opt_sectors < era->sectors_per_block ||
1734             do_div(io_opt_sectors, era->sectors_per_block)) {
1735                 blk_limits_io_min(limits, 0);
1736                 blk_limits_io_opt(limits, era->sectors_per_block << SECTOR_SHIFT);
1737         }
1738 }
1739
1740 /*----------------------------------------------------------------*/
1741
1742 static struct target_type era_target = {
1743         .name = "era",
1744         .version = {1, 0, 0},
1745         .module = THIS_MODULE,
1746         .ctr = era_ctr,
1747         .dtr = era_dtr,
1748         .map = era_map,
1749         .postsuspend = era_postsuspend,
1750         .preresume = era_preresume,
1751         .status = era_status,
1752         .message = era_message,
1753         .iterate_devices = era_iterate_devices,
1754         .io_hints = era_io_hints
1755 };
1756
1757 static int __init dm_era_init(void)
1758 {
1759         int r;
1760
1761         r = dm_register_target(&era_target);
1762         if (r) {
1763                 DMERR("era target registration failed: %d", r);
1764                 return r;
1765         }
1766
1767         return 0;
1768 }
1769
1770 static void __exit dm_era_exit(void)
1771 {
1772         dm_unregister_target(&era_target);
1773 }
1774
1775 module_init(dm_era_init);
1776 module_exit(dm_era_exit);
1777
1778 MODULE_DESCRIPTION(DM_NAME " era target");
1779 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
1780 MODULE_LICENSE("GPL");