git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/backpointers.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "bcachefs.h"
   3 #include "bbpos.h"
   4 #include "alloc_background.h"
   5 #include "backpointers.h"
   6 #include "btree_cache.h"
   7 #include "btree_update.h"
   8 #include "btree_update_interior.h"
   9 #include "btree_write_buffer.h"
  10 #include "error.h"
  11
  12 #include <linux/mm.h>
  13
  14 static bool extent_matches_bp(struct bch_fs *c,
  15                               enum btree_id btree_id, unsigned level,
  16                               struct bkey_s_c k,
  17                               struct bpos bucket,
  18                               struct bch_backpointer bp)
  19 {
  20         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  21         const union bch_extent_entry *entry;
  22         struct extent_ptr_decoded p;
  23
  24         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  25                 struct bpos bucket2;
  26                 struct bch_backpointer bp2;
  27
  28                 if (p.ptr.cached)
  29                         continue;
  30
  31                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  32                                       &bucket2, &bp2);
  33                 if (bpos_eq(bucket, bucket2) &&
  34                     !memcmp(&bp, &bp2, sizeof(bp)))
  35                         return true;
  36         }
  37
  38         return false;
  39 }
  40
  41 int bch2_backpointer_invalid(struct bch_fs *c, struct bkey_s_c k,
  42                              enum bkey_invalid_flags flags,
  43                              struct printbuf *err)
  44 {
  45         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  46         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  47         int ret = 0;
  48
  49         bkey_fsck_err_on(!bpos_eq(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset)),
  50                          c, err,
  51                          backpointer_pos_wrong,
  52                          "backpointer at wrong pos");
  53 fsck_err:
  54         return ret;
  55 }
  56
  57 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
  58 {
  59         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
  60                bch2_btree_id_str(bp->btree_id),
  61                bp->level,
  62                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  63                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  64                bp->bucket_len);
  65         bch2_bpos_to_text(out, bp->pos);
  66 }
  67
  68 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
  69 {
  70         prt_str(out, "bucket=");
  71         bch2_bpos_to_text(out, bp_pos_to_bucket(c, k.k->p));
  72         prt_str(out, " ");
  73
  74         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
  75 }
  76
  77 void bch2_backpointer_swab(struct bkey_s k)
  78 {
  79         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
  80
  81         bp.v->bucket_offset     = swab40(bp.v->bucket_offset);
  82         bp.v->bucket_len        = swab32(bp.v->bucket_len);
  83         bch2_bpos_swab(&bp.v->pos);
  84 }
  85
  86 static noinline int backpointer_mod_err(struct btree_trans *trans,
  87                                         struct bch_backpointer bp,
  88                                         struct bkey_s_c bp_k,
  89                                         struct bkey_s_c orig_k,
  90                                         bool insert)
  91 {
  92         struct bch_fs *c = trans->c;
  93         struct printbuf buf = PRINTBUF;
  94
  95         if (insert) {
  96                 prt_printf(&buf, "existing backpointer found when inserting ");
  97                 bch2_backpointer_to_text(&buf, &bp);
  98                 prt_newline(&buf);
  99                 printbuf_indent_add(&buf, 2);
 100
 101                 prt_printf(&buf, "found ");
 102                 bch2_bkey_val_to_text(&buf, c, bp_k);
 103                 prt_newline(&buf);
 104
 105                 prt_printf(&buf, "for ");
 106                 bch2_bkey_val_to_text(&buf, c, orig_k);
 107
 108                 bch_err(c, "%s", buf.buf);
 109         } else if (c->curr_recovery_pass > BCH_RECOVERY_PASS_check_extents_to_backpointers) {
 110                 prt_printf(&buf, "backpointer not found when deleting");
 111                 prt_newline(&buf);
 112                 printbuf_indent_add(&buf, 2);
 113
 114                 prt_printf(&buf, "searching for ");
 115                 bch2_backpointer_to_text(&buf, &bp);
 116                 prt_newline(&buf);
 117
 118                 prt_printf(&buf, "got ");
 119                 bch2_bkey_val_to_text(&buf, c, bp_k);
 120                 prt_newline(&buf);
 121
 122                 prt_printf(&buf, "for ");
 123                 bch2_bkey_val_to_text(&buf, c, orig_k);
 124
 125                 bch_err(c, "%s", buf.buf);
 126         }
 127
 128         printbuf_exit(&buf);
 129
 130         if (c->curr_recovery_pass > BCH_RECOVERY_PASS_check_extents_to_backpointers) {
 131                 bch2_inconsistent_error(c);
 132                 return -EIO;
 133         } else {
 134                 return 0;
 135         }
 136 }
 137
 138 int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 139                                 struct bpos bucket,
 140                                 struct bch_backpointer bp,
 141                                 struct bkey_s_c orig_k,
 142                                 bool insert)
 143 {
 144         struct btree_iter bp_iter;
 145         struct bkey_s_c k;
 146         struct bkey_i_backpointer *bp_k;
 147         int ret;
 148
 149         bp_k = bch2_trans_kmalloc_nomemzero(trans, sizeof(struct bkey_i_backpointer));
 150         ret = PTR_ERR_OR_ZERO(bp_k);
 151         if (ret)
 152                 return ret;
 153
 154         bkey_backpointer_init(&bp_k->k_i);
 155         bp_k->k.p = bucket_pos_to_bp(trans->c, bucket, bp.bucket_offset);
 156         bp_k->v = bp;
 157
 158         if (!insert) {
 159                 bp_k->k.type = KEY_TYPE_deleted;
 160                 set_bkey_val_u64s(&bp_k->k, 0);
 161         }
 162
 163         k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 164                                bp_k->k.p,
 165                                BTREE_ITER_INTENT|
 166                                BTREE_ITER_SLOTS|
 167                                BTREE_ITER_WITH_UPDATES);
 168         ret = bkey_err(k);
 169         if (ret)
 170                 goto err;
 171
 172         if (insert
 173             ? k.k->type
 174             : (k.k->type != KEY_TYPE_backpointer ||
 175                memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp)))) {
 176                 ret = backpointer_mod_err(trans, bp, k, orig_k, insert);
 177                 if (ret)
 178                         goto err;
 179         }
 180
 181         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 182 err:
 183         bch2_trans_iter_exit(trans, &bp_iter);
 184         return ret;
 185 }
 186
 187 /*
 188  * Find the next backpointer >= *bp_offset:
 189  */
 190 int bch2_get_next_backpointer(struct btree_trans *trans,
 191                               struct bpos bucket, int gen,
 192                               struct bpos *bp_pos,
 193                               struct bch_backpointer *bp,
 194                               unsigned iter_flags)
 195 {
 196         struct bch_fs *c = trans->c;
 197         struct bpos bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 198         struct btree_iter alloc_iter = { NULL }, bp_iter = { NULL };
 199         struct bkey_s_c k;
 200         int ret = 0;
 201
 202         if (bpos_ge(*bp_pos, bp_end_pos))
 203                 goto done;
 204
 205         if (gen >= 0) {
 206                 k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 207                                        bucket, BTREE_ITER_CACHED|iter_flags);
 208                 ret = bkey_err(k);
 209                 if (ret)
 210                         goto out;
 211
 212                 if (k.k->type != KEY_TYPE_alloc_v4 ||
 213                     bkey_s_c_to_alloc_v4(k).v->gen != gen)
 214                         goto done;
 215         }
 216
 217         *bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(c, bucket, 0));
 218
 219         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 220                                      *bp_pos, iter_flags, k, ret) {
 221                 if (bpos_ge(k.k->p, bp_end_pos))
 222                         break;
 223
 224                 *bp_pos = k.k->p;
 225                 *bp = *bkey_s_c_to_backpointer(k).v;
 226                 goto out;
 227         }
 228 done:
 229         *bp_pos = SPOS_MAX;
 230 out:
 231         bch2_trans_iter_exit(trans, &bp_iter);
 232         bch2_trans_iter_exit(trans, &alloc_iter);
 233         return ret;
 234 }
 235
 236 static void backpointer_not_found(struct btree_trans *trans,
 237                                   struct bpos bp_pos,
 238                                   struct bch_backpointer bp,
 239                                   struct bkey_s_c k)
 240 {
 241         struct bch_fs *c = trans->c;
 242         struct printbuf buf = PRINTBUF;
 243         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 244
 245         /*
 246          * If we're using the btree write buffer, the backpointer we were
 247          * looking at may have already been deleted - failure to find what it
 248          * pointed to is not an error:
 249          */
 250         if (likely(!bch2_backpointers_no_use_write_buffer))
 251                 return;
 252
 253         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 254                    bp.level ? "btree node" : "extent");
 255         prt_printf(&buf, "bucket: ");
 256         bch2_bpos_to_text(&buf, bucket);
 257         prt_printf(&buf, "\n  ");
 258
 259         prt_printf(&buf, "backpointer pos: ");
 260         bch2_bpos_to_text(&buf, bp_pos);
 261         prt_printf(&buf, "\n  ");
 262
 263         bch2_backpointer_to_text(&buf, &bp);
 264         prt_printf(&buf, "\n  ");
 265         bch2_bkey_val_to_text(&buf, c, k);
 266         if (c->curr_recovery_pass >= BCH_RECOVERY_PASS_check_extents_to_backpointers)
 267                 bch_err_ratelimited(c, "%s", buf.buf);
 268         else
 269                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 270
 271         printbuf_exit(&buf);
 272 }
 273
 274 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 275                                          struct btree_iter *iter,
 276                                          struct bpos bp_pos,
 277                                          struct bch_backpointer bp,
 278                                          unsigned iter_flags)
 279 {
 280         if (likely(!bp.level)) {
 281                 struct bch_fs *c = trans->c;
 282                 struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 283                 struct bkey_s_c k;
 284
 285                 bch2_trans_node_iter_init(trans, iter,
 286                                           bp.btree_id,
 287                                           bp.pos,
 288                                           0, 0,
 289                                           iter_flags);
 290                 k = bch2_btree_iter_peek_slot(iter);
 291                 if (bkey_err(k)) {
 292                         bch2_trans_iter_exit(trans, iter);
 293                         return k;
 294                 }
 295
 296                 if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 297                         return k;
 298
 299                 bch2_trans_iter_exit(trans, iter);
 300                 backpointer_not_found(trans, bp_pos, bp, k);
 301                 return bkey_s_c_null;
 302         } else {
 303                 struct btree *b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
 304
 305                 if (IS_ERR_OR_NULL(b)) {
 306                         bch2_trans_iter_exit(trans, iter);
 307                         return IS_ERR(b) ? bkey_s_c_err(PTR_ERR(b)) : bkey_s_c_null;
 308                 }
 309                 return bkey_i_to_s_c(&b->key);
 310         }
 311 }
 312
 313 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 314                                         struct btree_iter *iter,
 315                                         struct bpos bp_pos,
 316                                         struct bch_backpointer bp)
 317 {
 318         struct bch_fs *c = trans->c;
 319         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 320         struct btree *b;
 321
 322         BUG_ON(!bp.level);
 323
 324         bch2_trans_node_iter_init(trans, iter,
 325                                   bp.btree_id,
 326                                   bp.pos,
 327                                   0,
 328                                   bp.level - 1,
 329                                   0);
 330         b = bch2_btree_iter_peek_node(iter);
 331         if (IS_ERR_OR_NULL(b))
 332                 goto err;
 333
 334         BUG_ON(b->c.level != bp.level - 1);
 335
 336         if (extent_matches_bp(c, bp.btree_id, bp.level,
 337                               bkey_i_to_s_c(&b->key),
 338                               bucket, bp))
 339                 return b;
 340
 341         if (btree_node_will_make_reachable(b)) {
 342                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 343         } else {
 344                 backpointer_not_found(trans, bp_pos, bp, bkey_i_to_s_c(&b->key));
 345                 b = NULL;
 346         }
 347 err:
 348         bch2_trans_iter_exit(trans, iter);
 349         return b;
 350 }
 351
 352 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 353                                         struct bkey_s_c k)
 354 {
 355         struct bch_fs *c = trans->c;
 356         struct btree_iter alloc_iter = { NULL };
 357         struct bkey_s_c alloc_k;
 358         struct printbuf buf = PRINTBUF;
 359         int ret = 0;
 360
 361         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 362                         backpointer_to_missing_device,
 363                         "backpointer for missing device:\n%s",
 364                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 365                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 366                 goto out;
 367         }
 368
 369         alloc_k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 370                                      bp_pos_to_bucket(c, k.k->p), 0);
 371         ret = bkey_err(alloc_k);
 372         if (ret)
 373                 goto out;
 374
 375         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 376                         backpointer_to_missing_alloc,
 377                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 378                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 379                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 380                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 381                 goto out;
 382         }
 383 out:
 384 fsck_err:
 385         bch2_trans_iter_exit(trans, &alloc_iter);
 386         printbuf_exit(&buf);
 387         return ret;
 388 }
 389
 390 /* verify that every backpointer has a corresponding alloc key */
 391 int bch2_check_btree_backpointers(struct bch_fs *c)
 392 {
 393         struct btree_iter iter;
 394         struct bkey_s_c k;
 395         int ret;
 396
 397         ret = bch2_trans_run(c,
 398                 for_each_btree_key_commit(trans, iter,
 399                         BTREE_ID_backpointers, POS_MIN, 0, k,
 400                         NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 401                   bch2_check_btree_backpointer(trans, &iter, k)));
 402         if (ret)
 403                 bch_err_fn(c, ret);
 404         return ret;
 405 }
 406
 407 struct bpos_level {
 408         unsigned        level;
 409         struct bpos     pos;
 410 };
 411
 412 static int check_bp_exists(struct btree_trans *trans,
 413                            struct bpos bucket,
 414                            struct bch_backpointer bp,
 415                            struct bkey_s_c orig_k,
 416                            struct bpos bucket_start,
 417                            struct bpos bucket_end,
 418                            struct bpos_level *last_flushed)
 419 {
 420         struct bch_fs *c = trans->c;
 421         struct btree_iter bp_iter = { NULL };
 422         struct printbuf buf = PRINTBUF;
 423         struct bkey_s_c bp_k;
 424         int ret;
 425
 426         if (bpos_lt(bucket, bucket_start) ||
 427             bpos_gt(bucket, bucket_end))
 428                 return 0;
 429
 430         if (!bch2_dev_bucket_exists(c, bucket))
 431                 goto missing;
 432
 433         bp_k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 434                                   bucket_pos_to_bp(c, bucket, bp.bucket_offset),
 435                                   0);
 436         ret = bkey_err(bp_k);
 437         if (ret)
 438                 goto err;
 439
 440         if (bp_k.k->type != KEY_TYPE_backpointer ||
 441             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
 442                 if (last_flushed->level != bp.level ||
 443                     !bpos_eq(last_flushed->pos, orig_k.k->p)) {
 444                         last_flushed->level = bp.level;
 445                         last_flushed->pos = orig_k.k->p;
 446
 447                         ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 448                                 -BCH_ERR_transaction_restart_write_buffer_flush;
 449                         goto out;
 450                 }
 451                 goto missing;
 452         }
 453 out:
 454 err:
 455 fsck_err:
 456         bch2_trans_iter_exit(trans, &bp_iter);
 457         printbuf_exit(&buf);
 458         return ret;
 459 missing:
 460         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 461                bch2_btree_id_str(bp.btree_id), bp.level);
 462         bch2_bkey_val_to_text(&buf, c, orig_k);
 463         prt_printf(&buf, "\nbp pos ");
 464         bch2_bpos_to_text(&buf, bp_iter.pos);
 465
 466         if (c->sb.version_upgrade_complete < bcachefs_metadata_version_backpointers ||
 467             c->opts.reconstruct_alloc ||
 468             fsck_err(c, ptr_to_missing_backpointer, "%s", buf.buf))
 469                 ret = bch2_bucket_backpointer_mod(trans, bucket, bp, orig_k, true);
 470
 471         goto out;
 472 }
 473
 474 static int check_extent_to_backpointers(struct btree_trans *trans,
 475                                         enum btree_id btree, unsigned level,
 476                                         struct bpos bucket_start,
 477                                         struct bpos bucket_end,
 478                                         struct bpos_level *last_flushed,
 479                                         struct bkey_s_c k)
 480 {
 481         struct bch_fs *c = trans->c;
 482         struct bkey_ptrs_c ptrs;
 483         const union bch_extent_entry *entry;
 484         struct extent_ptr_decoded p;
 485         int ret;
 486
 487         ptrs = bch2_bkey_ptrs_c(k);
 488         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 489                 struct bpos bucket_pos;
 490                 struct bch_backpointer bp;
 491
 492                 if (p.ptr.cached)
 493                         continue;
 494
 495                 bch2_extent_ptr_to_bp(c, btree, level,
 496                                       k, p, &bucket_pos, &bp);
 497
 498                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 499                                       bucket_start, bucket_end,
 500                                       last_flushed);
 501                 if (ret)
 502                         return ret;
 503         }
 504
 505         return 0;
 506 }
 507
 508 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 509                                             enum btree_id btree_id,
 510                                             struct bpos bucket_start,
 511                                             struct bpos bucket_end,
 512                                             struct bpos_level *last_flushed,
 513                                             int *level)
 514 {
 515         struct bch_fs *c = trans->c;
 516         struct btree_iter iter;
 517         struct btree *b;
 518         struct bkey_s_c k;
 519         int ret;
 520 retry:
 521         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN,
 522                                   0, bch2_btree_id_root(c, btree_id)->b->c.level, 0);
 523         b = bch2_btree_iter_peek_node(&iter);
 524         ret = PTR_ERR_OR_ZERO(b);
 525         if (ret)
 526                 goto err;
 527
 528         if (b != btree_node_root(c, b)) {
 529                 bch2_trans_iter_exit(trans, &iter);
 530                 goto retry;
 531         }
 532
 533         *level = b->c.level;
 534
 535         k = bkey_i_to_s_c(&b->key);
 536         ret = check_extent_to_backpointers(trans, btree_id, b->c.level + 1,
 537                                       bucket_start, bucket_end,
 538                                       last_flushed, k);
 539 err:
 540         bch2_trans_iter_exit(trans, &iter);
 541         return ret;
 542 }
 543
 544 static inline struct bbpos bp_to_bbpos(struct bch_backpointer bp)
 545 {
 546         return (struct bbpos) {
 547                 .btree  = bp.btree_id,
 548                 .pos    = bp.pos,
 549         };
 550 }
 551
 552 static size_t btree_nodes_fit_in_ram(struct bch_fs *c)
 553 {
 554         struct sysinfo i;
 555         u64 mem_bytes;
 556
 557         si_meminfo(&i);
 558         mem_bytes = i.totalram * i.mem_unit;
 559         return div_u64(mem_bytes >> 1, btree_bytes(c));
 560 }
 561
 562 static int bch2_get_btree_in_memory_pos(struct btree_trans *trans,
 563                                         unsigned btree_leaf_mask,
 564                                         unsigned btree_interior_mask,
 565                                         struct bbpos start, struct bbpos *end)
 566 {
 567         struct btree_iter iter;
 568         struct bkey_s_c k;
 569         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 570         enum btree_id btree;
 571         int ret = 0;
 572
 573         for (btree = start.btree; btree < BTREE_ID_NR && !ret; btree++) {
 574                 unsigned depth = ((1U << btree) & btree_leaf_mask) ? 1 : 2;
 575
 576                 if (!((1U << btree) & btree_leaf_mask) &&
 577                     !((1U << btree) & btree_interior_mask))
 578                         continue;
 579
 580                 bch2_trans_node_iter_init(trans, &iter, btree,
 581                                           btree == start.btree ? start.pos : POS_MIN,
 582                                           0, depth, 0);
 583                 /*
 584                  * for_each_btree_key_contineu() doesn't check the return value
 585                  * from bch2_btree_iter_advance(), which is needed when
 586                  * iterating over interior nodes where we'll see keys at
 587                  * SPOS_MAX:
 588                  */
 589                 do {
 590                         k = __bch2_btree_iter_peek_and_restart(trans, &iter, 0);
 591                         ret = bkey_err(k);
 592                         if (!k.k || ret)
 593                                 break;
 594
 595                         --btree_nodes;
 596                         if (!btree_nodes) {
 597                                 *end = BBPOS(btree, k.k->p);
 598                                 bch2_trans_iter_exit(trans, &iter);
 599                                 return 0;
 600                         }
 601                 } while (bch2_btree_iter_advance(&iter));
 602                 bch2_trans_iter_exit(trans, &iter);
 603         }
 604
 605         *end = BBPOS_MAX;
 606         return ret;
 607 }
 608
 609 static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 610                                                    struct bpos bucket_start,
 611                                                    struct bpos bucket_end)
 612 {
 613         struct bch_fs *c = trans->c;
 614         struct btree_iter iter;
 615         enum btree_id btree_id;
 616         struct bkey_s_c k;
 617         struct bpos_level last_flushed = { UINT_MAX, POS_MIN };
 618         int ret = 0;
 619
 620         for (btree_id = 0; btree_id < btree_id_nr_alive(c); btree_id++) {
 621                 int level, depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 622
 623                 ret = commit_do(trans, NULL, NULL,
 624                                 BCH_TRANS_COMMIT_no_enospc,
 625                                 check_btree_root_to_backpointers(trans, btree_id,
 626                                                         bucket_start, bucket_end,
 627                                                         &last_flushed, &level));
 628                 if (ret)
 629                         return ret;
 630
 631                 while (level >= depth) {
 632                         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 633                                                   level,
 634                                                   BTREE_ITER_PREFETCH);
 635                         for_each_btree_key_continue(trans, iter, BTREE_ITER_PREFETCH, k, ret) {
 636                                 ret = commit_do(trans, NULL, NULL,
 637                                                 BCH_TRANS_COMMIT_no_enospc,
 638                                         check_extent_to_backpointers(trans, btree_id, level,
 639                                                                      bucket_start, bucket_end,
 640                                                                      &last_flushed, k));
 641                                 if (ret)
 642                                         break;
 643
 644                                 if (bpos_eq(iter.pos, SPOS_MAX))
 645                                         break;
 646                         }
 647                         bch2_trans_iter_exit(trans, &iter);
 648
 649                         if (ret)
 650                                 return ret;
 651
 652                         --level;
 653                 }
 654         }
 655
 656         return 0;
 657 }
 658
 659 static struct bpos bucket_pos_to_bp_safe(const struct bch_fs *c,
 660                                          struct bpos bucket)
 661 {
 662         return bch2_dev_exists2(c, bucket.inode)
 663                 ? bucket_pos_to_bp(c, bucket, 0)
 664                 : bucket;
 665 }
 666
 667 static int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 668                                         struct bpos start, struct bpos *end)
 669 {
 670         struct btree_iter alloc_iter;
 671         struct btree_iter bp_iter;
 672         struct bkey_s_c alloc_k, bp_k;
 673         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 674         bool alloc_end = false, bp_end = false;
 675         int ret = 0;
 676
 677         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 678                                   start, 0, 1, 0);
 679         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 680                                   bucket_pos_to_bp_safe(trans->c, start), 0, 1, 0);
 681         while (1) {
 682                 alloc_k = !alloc_end
 683                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 684                         : bkey_s_c_null;
 685                 bp_k = !bp_end
 686                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 687                         : bkey_s_c_null;
 688
 689                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 690                 if ((!alloc_k.k && !bp_k.k) || ret) {
 691                         *end = SPOS_MAX;
 692                         break;
 693                 }
 694
 695                 --btree_nodes;
 696                 if (!btree_nodes) {
 697                         *end = alloc_k.k ? alloc_k.k->p : SPOS_MAX;
 698                         break;
 699                 }
 700
 701                 if (bpos_lt(alloc_iter.pos, SPOS_MAX) &&
 702                     bpos_lt(bucket_pos_to_bp_safe(trans->c, alloc_iter.pos), bp_iter.pos)) {
 703                         if (!bch2_btree_iter_advance(&alloc_iter))
 704                                 alloc_end = true;
 705                 } else {
 706                         if (!bch2_btree_iter_advance(&bp_iter))
 707                                 bp_end = true;
 708                 }
 709         }
 710         bch2_trans_iter_exit(trans, &bp_iter);
 711         bch2_trans_iter_exit(trans, &alloc_iter);
 712         return ret;
 713 }
 714
 715 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 716 {
 717         struct btree_trans *trans = bch2_trans_get(c);
 718         struct bpos start = POS_MIN, end;
 719         int ret;
 720
 721         while (1) {
 722                 ret = bch2_get_alloc_in_memory_pos(trans, start, &end);
 723                 if (ret)
 724                         break;
 725
 726                 if (bpos_eq(start, POS_MIN) && !bpos_eq(end, SPOS_MAX))
 727                         bch_verbose(c, "%s(): alloc info does not fit in ram, running in multiple passes with %zu nodes per pass",
 728                                     __func__, btree_nodes_fit_in_ram(c));
 729
 730                 if (!bpos_eq(start, POS_MIN) || !bpos_eq(end, SPOS_MAX)) {
 731                         struct printbuf buf = PRINTBUF;
 732
 733                         prt_str(&buf, "check_extents_to_backpointers(): ");
 734                         bch2_bpos_to_text(&buf, start);
 735                         prt_str(&buf, "-");
 736                         bch2_bpos_to_text(&buf, end);
 737
 738                         bch_verbose(c, "%s", buf.buf);
 739                         printbuf_exit(&buf);
 740                 }
 741
 742                 ret = bch2_check_extents_to_backpointers_pass(trans, start, end);
 743                 if (ret || bpos_eq(end, SPOS_MAX))
 744                         break;
 745
 746                 start = bpos_successor(end);
 747         }
 748         bch2_trans_put(trans);
 749
 750         if (ret)
 751                 bch_err_fn(c, ret);
 752         return ret;
 753 }
 754
 755 static int check_one_backpointer(struct btree_trans *trans,
 756                                  struct bbpos start,
 757                                  struct bbpos end,
 758                                  struct bkey_s_c_backpointer bp,
 759                                  struct bpos *last_flushed_pos)
 760 {
 761         struct bch_fs *c = trans->c;
 762         struct btree_iter iter;
 763         struct bbpos pos = bp_to_bbpos(*bp.v);
 764         struct bkey_s_c k;
 765         struct printbuf buf = PRINTBUF;
 766         int ret;
 767
 768         if (bbpos_cmp(pos, start) < 0 ||
 769             bbpos_cmp(pos, end) > 0)
 770                 return 0;
 771
 772         k = bch2_backpointer_get_key(trans, &iter, bp.k->p, *bp.v, 0);
 773         ret = bkey_err(k);
 774         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 775                 return 0;
 776         if (ret)
 777                 return ret;
 778
 779         if (!k.k && !bpos_eq(*last_flushed_pos, bp.k->p)) {
 780                 *last_flushed_pos = bp.k->p;
 781                 ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 782                         -BCH_ERR_transaction_restart_write_buffer_flush;
 783                 goto out;
 784         }
 785
 786         if (fsck_err_on(!k.k, c,
 787                         backpointer_to_missing_ptr,
 788                         "backpointer for missing %s\n  %s",
 789                         bp.v->level ? "btree node" : "extent",
 790                         (bch2_bkey_val_to_text(&buf, c, bp.s_c), buf.buf))) {
 791                 ret = bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, bp.k->p);
 792                 goto out;
 793         }
 794 out:
 795 fsck_err:
 796         bch2_trans_iter_exit(trans, &iter);
 797         printbuf_exit(&buf);
 798         return ret;
 799 }
 800
 801 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
 802                                                    struct bbpos start,
 803                                                    struct bbpos end)
 804 {
 805         struct btree_iter iter;
 806         struct bkey_s_c k;
 807         struct bpos last_flushed_pos = SPOS_MAX;
 808
 809         return for_each_btree_key_commit(trans, iter, BTREE_ID_backpointers,
 810                                   POS_MIN, BTREE_ITER_PREFETCH, k,
 811                                   NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 812                 check_one_backpointer(trans, start, end,
 813                                       bkey_s_c_to_backpointer(k),
 814                                       &last_flushed_pos));
 815 }
 816
 817 int bch2_check_backpointers_to_extents(struct bch_fs *c)
 818 {
 819         struct btree_trans *trans = bch2_trans_get(c);
 820         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
 821         int ret;
 822
 823         while (1) {
 824                 ret = bch2_get_btree_in_memory_pos(trans,
 825                                                    (1U << BTREE_ID_extents)|
 826                                                    (1U << BTREE_ID_reflink),
 827                                                    ~0,
 828                                                    start, &end);
 829                 if (ret)
 830                         break;
 831
 832                 if (!bbpos_cmp(start, BBPOS_MIN) &&
 833                     bbpos_cmp(end, BBPOS_MAX))
 834                         bch_verbose(c, "%s(): extents do not fit in ram, running in multiple passes with %zu nodes per pass",
 835                                     __func__, btree_nodes_fit_in_ram(c));
 836
 837                 if (bbpos_cmp(start, BBPOS_MIN) ||
 838                     bbpos_cmp(end, BBPOS_MAX)) {
 839                         struct printbuf buf = PRINTBUF;
 840
 841                         prt_str(&buf, "check_backpointers_to_extents(): ");
 842                         bch2_bbpos_to_text(&buf, start);
 843                         prt_str(&buf, "-");
 844                         bch2_bbpos_to_text(&buf, end);
 845
 846                         bch_verbose(c, "%s", buf.buf);
 847                         printbuf_exit(&buf);
 848                 }
 849
 850                 ret = bch2_check_backpointers_to_extents_pass(trans, start, end);
 851                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
 852                         break;
 853
 854                 start = bbpos_successor(end);
 855         }
 856         bch2_trans_put(trans);
 857
 858         if (ret)
 859                 bch_err_fn(c, ret);
 860         return ret;
 861 }