drivers/md/persistent-data/dm-space-map-metadata.c

   1 /*
   2  * Copyright (C) 2011 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-space-map.h"
   8 #include "dm-space-map-common.h"
   9 #include "dm-space-map-metadata.h"
  10
  11 #include <linux/list.h>
  12 #include <linux/slab.h>
  13 #include <linux/device-mapper.h>
  14 #include <linux/kernel.h>
  15
  16 #define DM_MSG_PREFIX "space map metadata"
  17
  18 /*----------------------------------------------------------------*/
  19
  20 /*
  21  * An edge triggered threshold.
  22  */
  23 struct threshold {
  24         bool threshold_set;
  25         bool value_set;
  26         dm_block_t threshold;
  27         dm_block_t current_value;
  28         dm_sm_threshold_fn fn;
  29         void *context;
  30 };
  31
  32 static void threshold_init(struct threshold *t)
  33 {
  34         t->threshold_set = false;
  35         t->value_set = false;
  36 }
  37
  38 static void set_threshold(struct threshold *t, dm_block_t value,
  39                           dm_sm_threshold_fn fn, void *context)
  40 {
  41         t->threshold_set = true;
  42         t->threshold = value;
  43         t->fn = fn;
  44         t->context = context;
  45 }
  46
  47 static bool below_threshold(struct threshold *t, dm_block_t value)
  48 {
  49         return t->threshold_set && value <= t->threshold;
  50 }
  51
  52 static bool threshold_already_triggered(struct threshold *t)
  53 {
  54         return t->value_set && below_threshold(t, t->current_value);
  55 }
  56
  57 static void check_threshold(struct threshold *t, dm_block_t value)
  58 {
  59         if (below_threshold(t, value) &&
  60             !threshold_already_triggered(t))
  61                 t->fn(t->context);
  62
  63         t->value_set = true;
  64         t->current_value = value;
  65 }
  66
  67 /*----------------------------------------------------------------*/
  68
  69 /*
  70  * Space map interface.
  71  *
  72  * The low level disk format is written using the standard btree and
  73  * transaction manager.  This means that performing disk operations may
  74  * cause us to recurse into the space map in order to allocate new blocks.
  75  * For this reason we have a pool of pre-allocated blocks large enough to
  76  * service any metadata_ll_disk operation.
  77  */
  78
  79 /*
  80  * FIXME: we should calculate this based on the size of the device.
  81  * Only the metadata space map needs this functionality.
  82  */
  83 #define MAX_RECURSIVE_ALLOCATIONS 1024
  84
  85 enum block_op_type {
  86         BOP_INC,
  87         BOP_DEC
  88 };
  89
  90 struct block_op {
  91         enum block_op_type type;
  92         dm_block_t block;
  93 };
  94
  95 struct bop_ring_buffer {
  96         unsigned begin;
  97         unsigned end;
  98         struct block_op bops[MAX_RECURSIVE_ALLOCATIONS + 1];
  99 };
 100
 101 static void brb_init(struct bop_ring_buffer *brb)
 102 {
 103         brb->begin = 0;
 104         brb->end = 0;
 105 }
 106
 107 static bool brb_empty(struct bop_ring_buffer *brb)
 108 {
 109         return brb->begin == brb->end;
 110 }
 111
 112 static unsigned brb_next(struct bop_ring_buffer *brb, unsigned old)
 113 {
 114         unsigned r = old + 1;
 115         return r >= ARRAY_SIZE(brb->bops) ? 0 : r;
 116 }
 117
 118 static int brb_push(struct bop_ring_buffer *brb,
 119                     enum block_op_type type, dm_block_t b)
 120 {
 121         struct block_op *bop;
 122         unsigned next = brb_next(brb, brb->end);
 123
 124         /*
 125          * We don't allow the last bop to be filled, this way we can
 126          * differentiate between full and empty.
 127          */
 128         if (next == brb->begin)
 129                 return -ENOMEM;
 130
 131         bop = brb->bops + brb->end;
 132         bop->type = type;
 133         bop->block = b;
 134
 135         brb->end = next;
 136
 137         return 0;
 138 }
 139
 140 static int brb_peek(struct bop_ring_buffer *brb, struct block_op *result)
 141 {
 142         struct block_op *bop;
 143
 144         if (brb_empty(brb))
 145                 return -ENODATA;
 146
 147         bop = brb->bops + brb->begin;
 148         result->type = bop->type;
 149         result->block = bop->block;
 150
 151         return 0;
 152 }
 153
 154 static int brb_pop(struct bop_ring_buffer *brb)
 155 {
 156         if (brb_empty(brb))
 157                 return -ENODATA;
 158
 159         brb->begin = brb_next(brb, brb->begin);
 160
 161         return 0;
 162 }
 163
 164 /*----------------------------------------------------------------*/
 165
 166 struct sm_metadata {
 167         struct dm_space_map sm;
 168
 169         struct ll_disk ll;
 170         struct ll_disk old_ll;
 171
 172         dm_block_t begin;
 173
 174         unsigned recursion_count;
 175         unsigned allocated_this_transaction;
 176         struct bop_ring_buffer uncommitted;
 177
 178         struct threshold threshold;
 179 };
 180
 181 static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
 182 {
 183         int r = brb_push(&smm->uncommitted, type, b);
 184
 185         if (r) {
 186                 DMERR("too many recursive allocations");
 187                 return -ENOMEM;
 188         }
 189
 190         return 0;
 191 }
 192
 193 static int commit_bop(struct sm_metadata *smm, struct block_op *op)
 194 {
 195         int r = 0;
 196         enum allocation_event ev;
 197
 198         switch (op->type) {
 199         case BOP_INC:
 200                 r = sm_ll_inc(&smm->ll, op->block, &ev);
 201                 break;
 202
 203         case BOP_DEC:
 204                 r = sm_ll_dec(&smm->ll, op->block, &ev);
 205                 break;
 206         }
 207
 208         return r;
 209 }
 210
 211 static void in(struct sm_metadata *smm)
 212 {
 213         smm->recursion_count++;
 214 }
 215
 216 static int apply_bops(struct sm_metadata *smm)
 217 {
 218         int r = 0;
 219
 220         while (!brb_empty(&smm->uncommitted)) {
 221                 struct block_op bop;
 222
 223                 r = brb_peek(&smm->uncommitted, &bop);
 224                 if (r) {
 225                         DMERR("bug in bop ring buffer");
 226                         break;
 227                 }
 228
 229                 r = commit_bop(smm, &bop);
 230                 if (r)
 231                         break;
 232
 233                 brb_pop(&smm->uncommitted);
 234         }
 235
 236         return r;
 237 }
 238
 239 static int out(struct sm_metadata *smm)
 240 {
 241         int r = 0;
 242
 243         /*
 244          * If we're not recursing then very bad things are happening.
 245          */
 246         if (!smm->recursion_count) {
 247                 DMERR("lost track of recursion depth");
 248                 return -ENOMEM;
 249         }
 250
 251         if (smm->recursion_count == 1)
 252                 r = apply_bops(smm);
 253
 254         smm->recursion_count--;
 255
 256         return r;
 257 }
 258
 259 /*
 260  * When using the out() function above, we often want to combine an error
 261  * code for the operation run in the recursive context with that from
 262  * out().
 263  */
 264 static int combine_errors(int r1, int r2)
 265 {
 266         return r1 ? r1 : r2;
 267 }
 268
 269 static int recursing(struct sm_metadata *smm)
 270 {
 271         return smm->recursion_count;
 272 }
 273
 274 static void sm_metadata_destroy(struct dm_space_map *sm)
 275 {
 276         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 277
 278         kfree(smm);
 279 }
 280
 281 static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
 282 {
 283         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 284
 285         *count = smm->ll.nr_blocks;
 286
 287         return 0;
 288 }
 289
 290 static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
 291 {
 292         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 293
 294         *count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
 295                  smm->allocated_this_transaction;
 296
 297         return 0;
 298 }
 299
 300 static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
 301                                  uint32_t *result)
 302 {
 303         int r;
 304         unsigned i;
 305         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 306         unsigned adjustment = 0;
 307
 308         /*
 309          * We may have some uncommitted adjustments to add.  This list
 310          * should always be really short.
 311          */
 312         for (i = smm->uncommitted.begin;
 313              i != smm->uncommitted.end;
 314              i = brb_next(&smm->uncommitted, i)) {
 315                 struct block_op *op = smm->uncommitted.bops + i;
 316
 317                 if (op->block != b)
 318                         continue;
 319
 320                 switch (op->type) {
 321                 case BOP_INC:
 322                         adjustment++;
 323                         break;
 324
 325                 case BOP_DEC:
 326                         adjustment--;
 327                         break;
 328                 }
 329         }
 330
 331         r = sm_ll_lookup(&smm->ll, b, result);
 332         if (r)
 333                 return r;
 334
 335         *result += adjustment;
 336
 337         return 0;
 338 }
 339
 340 static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
 341                                               dm_block_t b, int *result)
 342 {
 343         int r, adjustment = 0;
 344         unsigned i;
 345         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 346         uint32_t rc;
 347
 348         /*
 349          * We may have some uncommitted adjustments to add.  This list
 350          * should always be really short.
 351          */
 352         for (i = smm->uncommitted.begin;
 353              i != smm->uncommitted.end;
 354              i = brb_next(&smm->uncommitted, i)) {
 355
 356                 struct block_op *op = smm->uncommitted.bops + i;
 357
 358                 if (op->block != b)
 359                         continue;
 360
 361                 switch (op->type) {
 362                 case BOP_INC:
 363                         adjustment++;
 364                         break;
 365
 366                 case BOP_DEC:
 367                         adjustment--;
 368                         break;
 369                 }
 370         }
 371
 372         if (adjustment > 1) {
 373                 *result = 1;
 374                 return 0;
 375         }
 376
 377         r = sm_ll_lookup_bitmap(&smm->ll, b, &rc);
 378         if (r)
 379                 return r;
 380
 381         if (rc == 3)
 382                 /*
 383                  * We err on the side of caution, and always return true.
 384                  */
 385                 *result = 1;
 386         else
 387                 *result = rc + adjustment > 1;
 388
 389         return 0;
 390 }
 391
 392 static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
 393                                  uint32_t count)
 394 {
 395         int r, r2;
 396         enum allocation_event ev;
 397         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 398
 399         if (smm->recursion_count) {
 400                 DMERR("cannot recurse set_count()");
 401                 return -EINVAL;
 402         }
 403
 404         in(smm);
 405         r = sm_ll_insert(&smm->ll, b, count, &ev);
 406         r2 = out(smm);
 407
 408         return combine_errors(r, r2);
 409 }
 410
 411 static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
 412 {
 413         int r, r2 = 0;
 414         enum allocation_event ev;
 415         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 416
 417         if (recursing(smm))
 418                 r = add_bop(smm, BOP_INC, b);
 419         else {
 420                 in(smm);
 421                 r = sm_ll_inc(&smm->ll, b, &ev);
 422                 r2 = out(smm);
 423         }
 424
 425         return combine_errors(r, r2);
 426 }
 427
 428 static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
 429 {
 430         int r, r2 = 0;
 431         enum allocation_event ev;
 432         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 433
 434         if (recursing(smm))
 435                 r = add_bop(smm, BOP_DEC, b);
 436         else {
 437                 in(smm);
 438                 r = sm_ll_dec(&smm->ll, b, &ev);
 439                 r2 = out(smm);
 440         }
 441
 442         return combine_errors(r, r2);
 443 }
 444
 445 static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b)
 446 {
 447         int r, r2 = 0;
 448         enum allocation_event ev;
 449         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 450
 451         r = sm_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
 452         if (r)
 453                 return r;
 454
 455         smm->begin = *b + 1;
 456
 457         if (recursing(smm))
 458                 r = add_bop(smm, BOP_INC, *b);
 459         else {
 460                 in(smm);
 461                 r = sm_ll_inc(&smm->ll, *b, &ev);
 462                 r2 = out(smm);
 463         }
 464
 465         if (!r)
 466                 smm->allocated_this_transaction++;
 467
 468         return combine_errors(r, r2);
 469 }
 470
 471 static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
 472 {
 473         dm_block_t count;
 474         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 475
 476         int r = sm_metadata_new_block_(sm, b);
 477         if (r) {
 478                 DMERR_LIMIT("unable to allocate new metadata block");
 479                 return r;
 480         }
 481
 482         r = sm_metadata_get_nr_free(sm, &count);
 483         if (r) {
 484                 DMERR_LIMIT("couldn't get free block count");
 485                 return r;
 486         }
 487
 488         check_threshold(&smm->threshold, count);
 489
 490         return r;
 491 }
 492
 493 static int sm_metadata_commit(struct dm_space_map *sm)
 494 {
 495         int r;
 496         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 497
 498         r = sm_ll_commit(&smm->ll);
 499         if (r)
 500                 return r;
 501
 502         memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
 503         smm->begin = 0;
 504         smm->allocated_this_transaction = 0;
 505
 506         return 0;
 507 }
 508
 509 static int sm_metadata_register_threshold_callback(struct dm_space_map *sm,
 510                                                    dm_block_t threshold,
 511                                                    dm_sm_threshold_fn fn,
 512                                                    void *context)
 513 {
 514         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 515
 516         set_threshold(&smm->threshold, threshold, fn, context);
 517
 518         return 0;
 519 }
 520
 521 static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
 522 {
 523         *result = sizeof(struct disk_sm_root);
 524
 525         return 0;
 526 }
 527
 528 static int sm_metadata_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
 529 {
 530         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 531         struct disk_sm_root root_le;
 532
 533         root_le.nr_blocks = cpu_to_le64(smm->ll.nr_blocks);
 534         root_le.nr_allocated = cpu_to_le64(smm->ll.nr_allocated);
 535         root_le.bitmap_root = cpu_to_le64(smm->ll.bitmap_root);
 536         root_le.ref_count_root = cpu_to_le64(smm->ll.ref_count_root);
 537
 538         if (max < sizeof(root_le))
 539                 return -ENOSPC;
 540
 541         memcpy(where_le, &root_le, sizeof(root_le));
 542
 543         return 0;
 544 }
 545
 546 static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks);
 547
 548 static const struct dm_space_map ops = {
 549         .destroy = sm_metadata_destroy,
 550         .extend = sm_metadata_extend,
 551         .get_nr_blocks = sm_metadata_get_nr_blocks,
 552         .get_nr_free = sm_metadata_get_nr_free,
 553         .get_count = sm_metadata_get_count,
 554         .count_is_more_than_one = sm_metadata_count_is_more_than_one,
 555         .set_count = sm_metadata_set_count,
 556         .inc_block = sm_metadata_inc_block,
 557         .dec_block = sm_metadata_dec_block,
 558         .new_block = sm_metadata_new_block,
 559         .commit = sm_metadata_commit,
 560         .root_size = sm_metadata_root_size,
 561         .copy_root = sm_metadata_copy_root,
 562         .register_threshold_callback = sm_metadata_register_threshold_callback
 563 };
 564
 565 /*----------------------------------------------------------------*/
 566
 567 /*
 568  * When a new space map is created that manages its own space.  We use
 569  * this tiny bootstrap allocator.
 570  */
 571 static void sm_bootstrap_destroy(struct dm_space_map *sm)
 572 {
 573 }
 574
 575 static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
 576 {
 577         DMERR("bootstrap doesn't support extend");
 578
 579         return -EINVAL;
 580 }
 581
 582 static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
 583 {
 584         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 585
 586         *count = smm->ll.nr_blocks;
 587
 588         return 0;
 589 }
 590
 591 static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
 592 {
 593         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 594
 595         *count = smm->ll.nr_blocks - smm->begin;
 596
 597         return 0;
 598 }
 599
 600 static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
 601                                   uint32_t *result)
 602 {
 603         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 604
 605         *result = (b < smm->begin) ? 1 : 0;
 606
 607         return 0;
 608 }
 609
 610 static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
 611                                                dm_block_t b, int *result)
 612 {
 613         *result = 0;
 614
 615         return 0;
 616 }
 617
 618 static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
 619                                   uint32_t count)
 620 {
 621         DMERR("bootstrap doesn't support set_count");
 622
 623         return -EINVAL;
 624 }
 625
 626 static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
 627 {
 628         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 629
 630         /*
 631          * We know the entire device is unused.
 632          */
 633         if (smm->begin == smm->ll.nr_blocks)
 634                 return -ENOSPC;
 635
 636         *b = smm->begin++;
 637
 638         return 0;
 639 }
 640
 641 static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
 642 {
 643         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 644
 645         return add_bop(smm, BOP_INC, b);
 646 }
 647
 648 static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
 649 {
 650         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 651
 652         return add_bop(smm, BOP_DEC, b);
 653 }
 654
 655 static int sm_bootstrap_commit(struct dm_space_map *sm)
 656 {
 657         return 0;
 658 }
 659
 660 static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
 661 {
 662         DMERR("bootstrap doesn't support root_size");
 663
 664         return -EINVAL;
 665 }
 666
 667 static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
 668                                   size_t max)
 669 {
 670         DMERR("bootstrap doesn't support copy_root");
 671
 672         return -EINVAL;
 673 }
 674
 675 static const struct dm_space_map bootstrap_ops = {
 676         .destroy = sm_bootstrap_destroy,
 677         .extend = sm_bootstrap_extend,
 678         .get_nr_blocks = sm_bootstrap_get_nr_blocks,
 679         .get_nr_free = sm_bootstrap_get_nr_free,
 680         .get_count = sm_bootstrap_get_count,
 681         .count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
 682         .set_count = sm_bootstrap_set_count,
 683         .inc_block = sm_bootstrap_inc_block,
 684         .dec_block = sm_bootstrap_dec_block,
 685         .new_block = sm_bootstrap_new_block,
 686         .commit = sm_bootstrap_commit,
 687         .root_size = sm_bootstrap_root_size,
 688         .copy_root = sm_bootstrap_copy_root,
 689         .register_threshold_callback = NULL
 690 };
 691
 692 /*----------------------------------------------------------------*/
 693
 694 static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
 695 {
 696         int r, i;
 697         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 698         dm_block_t old_len = smm->ll.nr_blocks;
 699
 700         /*
 701          * Flick into a mode where all blocks get allocated in the new area.
 702          */
 703         smm->begin = old_len;
 704         memcpy(sm, &bootstrap_ops, sizeof(*sm));
 705
 706         /*
 707          * Extend.
 708          */
 709         r = sm_ll_extend(&smm->ll, extra_blocks);
 710         if (r)
 711                 goto out;
 712
 713         /*
 714          * We repeatedly increment then commit until the commit doesn't
 715          * allocate any new blocks.
 716          */
 717         do {
 718                 for (i = old_len; !r && i < smm->begin; i++)
 719                         r = add_bop(smm, BOP_INC, i);
 720
 721                 if (r)
 722                         goto out;
 723
 724                 old_len = smm->begin;
 725
 726                 r = apply_bops(smm);
 727                 if (r) {
 728                         DMERR("%s: apply_bops failed", __func__);
 729                         goto out;
 730                 }
 731
 732                 r = sm_ll_commit(&smm->ll);
 733                 if (r)
 734                         goto out;
 735
 736         } while (old_len != smm->begin);
 737
 738 out:
 739         /*
 740          * Switch back to normal behaviour.
 741          */
 742         memcpy(sm, &ops, sizeof(*sm));
 743         return r;
 744 }
 745
 746 /*----------------------------------------------------------------*/
 747
 748 struct dm_space_map *dm_sm_metadata_init(void)
 749 {
 750         struct sm_metadata *smm;
 751
 752         smm = kmalloc(sizeof(*smm), GFP_KERNEL);
 753         if (!smm)
 754                 return ERR_PTR(-ENOMEM);
 755
 756         memcpy(&smm->sm, &ops, sizeof(smm->sm));
 757
 758         return &smm->sm;
 759 }
 760
 761 int dm_sm_metadata_create(struct dm_space_map *sm,
 762                           struct dm_transaction_manager *tm,
 763                           dm_block_t nr_blocks,
 764                           dm_block_t superblock)
 765 {
 766         int r;
 767         dm_block_t i;
 768         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 769
 770         smm->begin = superblock + 1;
 771         smm->recursion_count = 0;
 772         smm->allocated_this_transaction = 0;
 773         brb_init(&smm->uncommitted);
 774         threshold_init(&smm->threshold);
 775
 776         memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
 777
 778         r = sm_ll_new_metadata(&smm->ll, tm);
 779         if (!r) {
 780                 if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
 781                         nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
 782                 r = sm_ll_extend(&smm->ll, nr_blocks);
 783         }
 784         memcpy(&smm->sm, &ops, sizeof(smm->sm));
 785         if (r)
 786                 return r;
 787
 788         /*
 789          * Now we need to update the newly created data structures with the
 790          * allocated blocks that they were built from.
 791          */
 792         for (i = superblock; !r && i < smm->begin; i++)
 793                 r = add_bop(smm, BOP_INC, i);
 794
 795         if (r)
 796                 return r;
 797
 798         r = apply_bops(smm);
 799         if (r) {
 800                 DMERR("%s: apply_bops failed", __func__);
 801                 return r;
 802         }
 803
 804         return sm_metadata_commit(sm);
 805 }
 806
 807 int dm_sm_metadata_open(struct dm_space_map *sm,
 808                         struct dm_transaction_manager *tm,
 809                         void *root_le, size_t len)
 810 {
 811         int r;
 812         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 813
 814         r = sm_ll_open_metadata(&smm->ll, tm, root_le, len);
 815         if (r)
 816                 return r;
 817
 818         smm->begin = 0;
 819         smm->recursion_count = 0;
 820         smm->allocated_this_transaction = 0;
 821         brb_init(&smm->uncommitted);
 822         threshold_init(&smm->threshold);
 823
 824         memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
 825         return 0;
 826 }