git.sesse.net Git - bcachefs-tools-debian/blob - c_src/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 "bkey_buf.h"
   7 #include "btree_cache.h"
   8 #include "btree_update.h"
   9 #include "btree_update_interior.h"
  10 #include "btree_write_buffer.h"
  11 #include "error.h"
  12
  13 #include <linux/mm.h>
  14
  15 static bool extent_matches_bp(struct bch_fs *c,
  16                               enum btree_id btree_id, unsigned level,
  17                               struct bkey_s_c k,
  18                               struct bpos bucket,
  19                               struct bch_backpointer bp)
  20 {
  21         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  22         const union bch_extent_entry *entry;
  23         struct extent_ptr_decoded p;
  24
  25         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  26                 struct bpos bucket2;
  27                 struct bch_backpointer bp2;
  28
  29                 if (p.ptr.cached)
  30                         continue;
  31
  32                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  33                                       &bucket2, &bp2);
  34                 if (bpos_eq(bucket, bucket2) &&
  35                     !memcmp(&bp, &bp2, sizeof(bp)))
  36                         return true;
  37         }
  38
  39         return false;
  40 }
  41
  42 int bch2_backpointer_invalid(struct bch_fs *c, struct bkey_s_c k,
  43                              enum bkey_invalid_flags flags,
  44                              struct printbuf *err)
  45 {
  46         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  47         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  48         int ret = 0;
  49
  50         bkey_fsck_err_on(!bpos_eq(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset)),
  51                          c, err,
  52                          backpointer_pos_wrong,
  53                          "backpointer at wrong pos");
  54 fsck_err:
  55         return ret;
  56 }
  57
  58 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
  59 {
  60         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
  61                bch2_btree_id_str(bp->btree_id),
  62                bp->level,
  63                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  64                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  65                bp->bucket_len);
  66         bch2_bpos_to_text(out, bp->pos);
  67 }
  68
  69 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
  70 {
  71         prt_str(out, "bucket=");
  72         bch2_bpos_to_text(out, bp_pos_to_bucket(c, k.k->p));
  73         prt_str(out, " ");
  74
  75         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
  76 }
  77
  78 void bch2_backpointer_swab(struct bkey_s k)
  79 {
  80         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
  81
  82         bp.v->bucket_offset     = swab40(bp.v->bucket_offset);
  83         bp.v->bucket_len        = swab32(bp.v->bucket_len);
  84         bch2_bpos_swab(&bp.v->pos);
  85 }
  86
  87 static noinline int backpointer_mod_err(struct btree_trans *trans,
  88                                         struct bch_backpointer bp,
  89                                         struct bkey_s_c bp_k,
  90                                         struct bkey_s_c orig_k,
  91                                         bool insert)
  92 {
  93         struct bch_fs *c = trans->c;
  94         struct printbuf buf = PRINTBUF;
  95
  96         if (insert) {
  97                 prt_printf(&buf, "existing backpointer found when inserting ");
  98                 bch2_backpointer_to_text(&buf, &bp);
  99                 prt_newline(&buf);
 100                 printbuf_indent_add(&buf, 2);
 101
 102                 prt_printf(&buf, "found ");
 103                 bch2_bkey_val_to_text(&buf, c, bp_k);
 104                 prt_newline(&buf);
 105
 106                 prt_printf(&buf, "for ");
 107                 bch2_bkey_val_to_text(&buf, c, orig_k);
 108
 109                 bch_err(c, "%s", buf.buf);
 110         } else if (c->curr_recovery_pass > BCH_RECOVERY_PASS_check_extents_to_backpointers) {
 111                 prt_printf(&buf, "backpointer not found when deleting");
 112                 prt_newline(&buf);
 113                 printbuf_indent_add(&buf, 2);
 114
 115                 prt_printf(&buf, "searching for ");
 116                 bch2_backpointer_to_text(&buf, &bp);
 117                 prt_newline(&buf);
 118
 119                 prt_printf(&buf, "got ");
 120                 bch2_bkey_val_to_text(&buf, c, bp_k);
 121                 prt_newline(&buf);
 122
 123                 prt_printf(&buf, "for ");
 124                 bch2_bkey_val_to_text(&buf, c, orig_k);
 125
 126                 bch_err(c, "%s", buf.buf);
 127         }
 128
 129         printbuf_exit(&buf);
 130
 131         if (c->curr_recovery_pass > BCH_RECOVERY_PASS_check_extents_to_backpointers) {
 132                 bch2_inconsistent_error(c);
 133                 return -EIO;
 134         } else {
 135                 return 0;
 136         }
 137 }
 138
 139 int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 140                                 struct bpos bucket,
 141                                 struct bch_backpointer bp,
 142                                 struct bkey_s_c orig_k,
 143                                 bool insert)
 144 {
 145         struct btree_iter bp_iter;
 146         struct bkey_s_c k;
 147         struct bkey_i_backpointer *bp_k;
 148         int ret;
 149
 150         bp_k = bch2_trans_kmalloc_nomemzero(trans, sizeof(struct bkey_i_backpointer));
 151         ret = PTR_ERR_OR_ZERO(bp_k);
 152         if (ret)
 153                 return ret;
 154
 155         bkey_backpointer_init(&bp_k->k_i);
 156         bp_k->k.p = bucket_pos_to_bp(trans->c, bucket, bp.bucket_offset);
 157         bp_k->v = bp;
 158
 159         if (!insert) {
 160                 bp_k->k.type = KEY_TYPE_deleted;
 161                 set_bkey_val_u64s(&bp_k->k, 0);
 162         }
 163
 164         k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 165                                bp_k->k.p,
 166                                BTREE_ITER_INTENT|
 167                                BTREE_ITER_SLOTS|
 168                                BTREE_ITER_WITH_UPDATES);
 169         ret = bkey_err(k);
 170         if (ret)
 171                 goto err;
 172
 173         if (insert
 174             ? k.k->type
 175             : (k.k->type != KEY_TYPE_backpointer ||
 176                memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp)))) {
 177                 ret = backpointer_mod_err(trans, bp, k, orig_k, insert);
 178                 if (ret)
 179                         goto err;
 180         }
 181
 182         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 183 err:
 184         bch2_trans_iter_exit(trans, &bp_iter);
 185         return ret;
 186 }
 187
 188 /*
 189  * Find the next backpointer >= *bp_offset:
 190  */
 191 int bch2_get_next_backpointer(struct btree_trans *trans,
 192                               struct bpos bucket, int gen,
 193                               struct bpos *bp_pos,
 194                               struct bch_backpointer *bp,
 195                               unsigned iter_flags)
 196 {
 197         struct bch_fs *c = trans->c;
 198         struct bpos bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 199         struct btree_iter alloc_iter = { NULL }, bp_iter = { NULL };
 200         struct bkey_s_c k;
 201         int ret = 0;
 202
 203         if (bpos_ge(*bp_pos, bp_end_pos))
 204                 goto done;
 205
 206         if (gen >= 0) {
 207                 k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 208                                        bucket, BTREE_ITER_CACHED|iter_flags);
 209                 ret = bkey_err(k);
 210                 if (ret)
 211                         goto out;
 212
 213                 if (k.k->type != KEY_TYPE_alloc_v4 ||
 214                     bkey_s_c_to_alloc_v4(k).v->gen != gen)
 215                         goto done;
 216         }
 217
 218         *bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(c, bucket, 0));
 219
 220         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 221                                      *bp_pos, iter_flags, k, ret) {
 222                 if (bpos_ge(k.k->p, bp_end_pos))
 223                         break;
 224
 225                 *bp_pos = k.k->p;
 226                 *bp = *bkey_s_c_to_backpointer(k).v;
 227                 goto out;
 228         }
 229 done:
 230         *bp_pos = SPOS_MAX;
 231 out:
 232         bch2_trans_iter_exit(trans, &bp_iter);
 233         bch2_trans_iter_exit(trans, &alloc_iter);
 234         return ret;
 235 }
 236
 237 static void backpointer_not_found(struct btree_trans *trans,
 238                                   struct bpos bp_pos,
 239                                   struct bch_backpointer bp,
 240                                   struct bkey_s_c k)
 241 {
 242         struct bch_fs *c = trans->c;
 243         struct printbuf buf = PRINTBUF;
 244         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 245
 246         /*
 247          * If we're using the btree write buffer, the backpointer we were
 248          * looking at may have already been deleted - failure to find what it
 249          * pointed to is not an error:
 250          */
 251         if (likely(!bch2_backpointers_no_use_write_buffer))
 252                 return;
 253
 254         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 255                    bp.level ? "btree node" : "extent");
 256         prt_printf(&buf, "bucket: ");
 257         bch2_bpos_to_text(&buf, bucket);
 258         prt_printf(&buf, "\n  ");
 259
 260         prt_printf(&buf, "backpointer pos: ");
 261         bch2_bpos_to_text(&buf, bp_pos);
 262         prt_printf(&buf, "\n  ");
 263
 264         bch2_backpointer_to_text(&buf, &bp);
 265         prt_printf(&buf, "\n  ");
 266         bch2_bkey_val_to_text(&buf, c, k);
 267         if (c->curr_recovery_pass >= BCH_RECOVERY_PASS_check_extents_to_backpointers)
 268                 bch_err_ratelimited(c, "%s", buf.buf);
 269         else
 270                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 271
 272         printbuf_exit(&buf);
 273 }
 274
 275 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 276                                          struct btree_iter *iter,
 277                                          struct bpos bp_pos,
 278                                          struct bch_backpointer bp,
 279                                          unsigned iter_flags)
 280 {
 281         if (likely(!bp.level)) {
 282                 struct bch_fs *c = trans->c;
 283                 struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 284                 struct bkey_s_c k;
 285
 286                 bch2_trans_node_iter_init(trans, iter,
 287                                           bp.btree_id,
 288                                           bp.pos,
 289                                           0, 0,
 290                                           iter_flags);
 291                 k = bch2_btree_iter_peek_slot(iter);
 292                 if (bkey_err(k)) {
 293                         bch2_trans_iter_exit(trans, iter);
 294                         return k;
 295                 }
 296
 297                 if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 298                         return k;
 299
 300                 bch2_trans_iter_exit(trans, iter);
 301                 backpointer_not_found(trans, bp_pos, bp, k);
 302                 return bkey_s_c_null;
 303         } else {
 304                 struct btree *b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
 305
 306                 if (IS_ERR_OR_NULL(b)) {
 307                         bch2_trans_iter_exit(trans, iter);
 308                         return IS_ERR(b) ? bkey_s_c_err(PTR_ERR(b)) : bkey_s_c_null;
 309                 }
 310                 return bkey_i_to_s_c(&b->key);
 311         }
 312 }
 313
 314 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 315                                         struct btree_iter *iter,
 316                                         struct bpos bp_pos,
 317                                         struct bch_backpointer bp)
 318 {
 319         struct bch_fs *c = trans->c;
 320         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 321         struct btree *b;
 322
 323         BUG_ON(!bp.level);
 324
 325         bch2_trans_node_iter_init(trans, iter,
 326                                   bp.btree_id,
 327                                   bp.pos,
 328                                   0,
 329                                   bp.level - 1,
 330                                   0);
 331         b = bch2_btree_iter_peek_node(iter);
 332         if (IS_ERR_OR_NULL(b))
 333                 goto err;
 334
 335         BUG_ON(b->c.level != bp.level - 1);
 336
 337         if (extent_matches_bp(c, bp.btree_id, bp.level,
 338                               bkey_i_to_s_c(&b->key),
 339                               bucket, bp))
 340                 return b;
 341
 342         if (btree_node_will_make_reachable(b)) {
 343                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 344         } else {
 345                 backpointer_not_found(trans, bp_pos, bp, bkey_i_to_s_c(&b->key));
 346                 b = NULL;
 347         }
 348 err:
 349         bch2_trans_iter_exit(trans, iter);
 350         return b;
 351 }
 352
 353 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 354                                         struct bkey_s_c k)
 355 {
 356         struct bch_fs *c = trans->c;
 357         struct btree_iter alloc_iter = { NULL };
 358         struct bkey_s_c alloc_k;
 359         struct printbuf buf = PRINTBUF;
 360         int ret = 0;
 361
 362         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 363                         backpointer_to_missing_device,
 364                         "backpointer for missing device:\n%s",
 365                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 366                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 367                 goto out;
 368         }
 369
 370         alloc_k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 371                                      bp_pos_to_bucket(c, k.k->p), 0);
 372         ret = bkey_err(alloc_k);
 373         if (ret)
 374                 goto out;
 375
 376         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 377                         backpointer_to_missing_alloc,
 378                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 379                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 380                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 381                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 382                 goto out;
 383         }
 384 out:
 385 fsck_err:
 386         bch2_trans_iter_exit(trans, &alloc_iter);
 387         printbuf_exit(&buf);
 388         return ret;
 389 }
 390
 391 /* verify that every backpointer has a corresponding alloc key */
 392 int bch2_check_btree_backpointers(struct bch_fs *c)
 393 {
 394         int ret = bch2_trans_run(c,
 395                 for_each_btree_key_commit(trans, iter,
 396                         BTREE_ID_backpointers, POS_MIN, 0, k,
 397                         NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 398                   bch2_check_btree_backpointer(trans, &iter, k)));
 399         bch_err_fn(c, ret);
 400         return ret;
 401 }
 402
 403 static int check_bp_exists(struct btree_trans *trans,
 404                            struct bpos bucket,
 405                            struct bch_backpointer bp,
 406                            struct bkey_s_c orig_k,
 407                            struct bpos bucket_start,
 408                            struct bpos bucket_end,
 409                            struct bkey_buf *last_flushed)
 410 {
 411         struct bch_fs *c = trans->c;
 412         struct btree_iter bp_iter = { NULL };
 413         struct printbuf buf = PRINTBUF;
 414         struct bkey_s_c bp_k;
 415         struct bkey_buf tmp;
 416         int ret;
 417
 418         bch2_bkey_buf_init(&tmp);
 419
 420         if (bpos_lt(bucket, bucket_start) ||
 421             bpos_gt(bucket, bucket_end))
 422                 return 0;
 423
 424         if (!bch2_dev_bucket_exists(c, bucket))
 425                 goto missing;
 426
 427         bp_k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 428                                   bucket_pos_to_bp(c, bucket, bp.bucket_offset),
 429                                   0);
 430         ret = bkey_err(bp_k);
 431         if (ret)
 432                 goto err;
 433
 434         if (bp_k.k->type != KEY_TYPE_backpointer ||
 435             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
 436                 if (!bpos_eq(orig_k.k->p, last_flushed->k->k.p) ||
 437                     bkey_bytes(orig_k.k) != bkey_bytes(&last_flushed->k->k) ||
 438                     memcmp(orig_k.v, &last_flushed->k->v, bkey_val_bytes(orig_k.k))) {
 439                         bch2_bkey_buf_reassemble(&tmp, c, orig_k);
 440
 441                         if (bp.level) {
 442                                 bch2_trans_unlock(trans);
 443                                 bch2_btree_interior_updates_flush(c);
 444                         }
 445
 446                         ret = bch2_btree_write_buffer_flush_sync(trans);
 447                         if (ret)
 448                                 goto err;
 449
 450                         bch2_bkey_buf_copy(last_flushed, c, tmp.k);
 451                         ret = -BCH_ERR_transaction_restart_write_buffer_flush;
 452                         goto out;
 453                 }
 454                 goto missing;
 455         }
 456 out:
 457 err:
 458 fsck_err:
 459         bch2_trans_iter_exit(trans, &bp_iter);
 460         bch2_bkey_buf_exit(&tmp, c);
 461         printbuf_exit(&buf);
 462         return ret;
 463 missing:
 464         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 465                bch2_btree_id_str(bp.btree_id), bp.level);
 466         bch2_bkey_val_to_text(&buf, c, orig_k);
 467         prt_printf(&buf, "\nbp pos ");
 468         bch2_bpos_to_text(&buf, bp_iter.pos);
 469
 470         if (c->opts.reconstruct_alloc ||
 471             fsck_err(c, ptr_to_missing_backpointer, "%s", buf.buf))
 472                 ret = bch2_bucket_backpointer_mod(trans, bucket, bp, orig_k, true);
 473
 474         goto out;
 475 }
 476
 477 static int check_extent_to_backpointers(struct btree_trans *trans,
 478                                         enum btree_id btree, unsigned level,
 479                                         struct bpos bucket_start,
 480                                         struct bpos bucket_end,
 481                                         struct bkey_buf *last_flushed,
 482                                         struct bkey_s_c k)
 483 {
 484         struct bch_fs *c = trans->c;
 485         struct bkey_ptrs_c ptrs;
 486         const union bch_extent_entry *entry;
 487         struct extent_ptr_decoded p;
 488         int ret;
 489
 490         ptrs = bch2_bkey_ptrs_c(k);
 491         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 492                 struct bpos bucket_pos;
 493                 struct bch_backpointer bp;
 494
 495                 if (p.ptr.cached)
 496                         continue;
 497
 498                 bch2_extent_ptr_to_bp(c, btree, level,
 499                                       k, p, &bucket_pos, &bp);
 500
 501                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 502                                       bucket_start, bucket_end,
 503                                       last_flushed);
 504                 if (ret)
 505                         return ret;
 506         }
 507
 508         return 0;
 509 }
 510
 511 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 512                                             enum btree_id btree_id,
 513                                             struct bpos bucket_start,
 514                                             struct bpos bucket_end,
 515                                             struct bkey_buf *last_flushed,
 516                                             int *level)
 517 {
 518         struct bch_fs *c = trans->c;
 519         struct btree_iter iter;
 520         struct btree *b;
 521         struct bkey_s_c k;
 522         int ret;
 523 retry:
 524         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN,
 525                                   0, bch2_btree_id_root(c, btree_id)->b->c.level, 0);
 526         b = bch2_btree_iter_peek_node(&iter);
 527         ret = PTR_ERR_OR_ZERO(b);
 528         if (ret)
 529                 goto err;
 530
 531         if (b != btree_node_root(c, b)) {
 532                 bch2_trans_iter_exit(trans, &iter);
 533                 goto retry;
 534         }
 535
 536         *level = b->c.level;
 537
 538         k = bkey_i_to_s_c(&b->key);
 539         ret = check_extent_to_backpointers(trans, btree_id, b->c.level + 1,
 540                                       bucket_start, bucket_end,
 541                                       last_flushed, k);
 542 err:
 543         bch2_trans_iter_exit(trans, &iter);
 544         return ret;
 545 }
 546
 547 static inline struct bbpos bp_to_bbpos(struct bch_backpointer bp)
 548 {
 549         return (struct bbpos) {
 550                 .btree  = bp.btree_id,
 551                 .pos    = bp.pos,
 552         };
 553 }
 554
 555 static size_t btree_nodes_fit_in_ram(struct bch_fs *c)
 556 {
 557         struct sysinfo i;
 558         u64 mem_bytes;
 559
 560         si_meminfo(&i);
 561         mem_bytes = i.totalram * i.mem_unit;
 562         return div_u64(mem_bytes >> 1, btree_bytes(c));
 563 }
 564
 565 static int bch2_get_btree_in_memory_pos(struct btree_trans *trans,
 566                                         unsigned btree_leaf_mask,
 567                                         unsigned btree_interior_mask,
 568                                         struct bbpos start, struct bbpos *end)
 569 {
 570         struct btree_iter iter;
 571         struct bkey_s_c k;
 572         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 573         enum btree_id btree;
 574         int ret = 0;
 575
 576         for (btree = start.btree; btree < BTREE_ID_NR && !ret; btree++) {
 577                 unsigned depth = ((1U << btree) & btree_leaf_mask) ? 1 : 2;
 578
 579                 if (!((1U << btree) & btree_leaf_mask) &&
 580                     !((1U << btree) & btree_interior_mask))
 581                         continue;
 582
 583                 bch2_trans_node_iter_init(trans, &iter, btree,
 584                                           btree == start.btree ? start.pos : POS_MIN,
 585                                           0, depth, 0);
 586                 /*
 587                  * for_each_btree_key_contineu() doesn't check the return value
 588                  * from bch2_btree_iter_advance(), which is needed when
 589                  * iterating over interior nodes where we'll see keys at
 590                  * SPOS_MAX:
 591                  */
 592                 do {
 593                         k = __bch2_btree_iter_peek_and_restart(trans, &iter, 0);
 594                         ret = bkey_err(k);
 595                         if (!k.k || ret)
 596                                 break;
 597
 598                         --btree_nodes;
 599                         if (!btree_nodes) {
 600                                 *end = BBPOS(btree, k.k->p);
 601                                 bch2_trans_iter_exit(trans, &iter);
 602                                 return 0;
 603                         }
 604                 } while (bch2_btree_iter_advance(&iter));
 605                 bch2_trans_iter_exit(trans, &iter);
 606         }
 607
 608         *end = BBPOS_MAX;
 609         return ret;
 610 }
 611
 612 static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 613                                                    struct bpos bucket_start,
 614                                                    struct bpos bucket_end)
 615 {
 616         struct bch_fs *c = trans->c;
 617         struct btree_iter iter;
 618         enum btree_id btree_id;
 619         struct bkey_s_c k;
 620         struct bkey_buf last_flushed;
 621         int ret = 0;
 622
 623         bch2_bkey_buf_init(&last_flushed);
 624         bkey_init(&last_flushed.k->k);
 625
 626         for (btree_id = 0; btree_id < btree_id_nr_alive(c); btree_id++) {
 627                 int level, depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 628
 629                 ret = commit_do(trans, NULL, NULL,
 630                                 BCH_TRANS_COMMIT_no_enospc,
 631                                 check_btree_root_to_backpointers(trans, btree_id,
 632                                                         bucket_start, bucket_end,
 633                                                         &last_flushed, &level));
 634                 if (ret)
 635                         return ret;
 636
 637                 while (level >= depth) {
 638                         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 639                                                   level,
 640                                                   BTREE_ITER_PREFETCH);
 641                         while (1) {
 642                                 bch2_trans_begin(trans);
 643                                 k = bch2_btree_iter_peek(&iter);
 644                                 if (!k.k)
 645                                         break;
 646                                 ret = bkey_err(k) ?:
 647                                         check_extent_to_backpointers(trans, btree_id, level,
 648                                                                      bucket_start, bucket_end,
 649                                                                      &last_flushed, k) ?:
 650                                         bch2_trans_commit(trans, NULL, NULL,
 651                                                           BCH_TRANS_COMMIT_no_enospc);
 652                                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
 653                                         ret = 0;
 654                                         continue;
 655                                 }
 656                                 if (ret)
 657                                         break;
 658                                 if (bpos_eq(iter.pos, SPOS_MAX))
 659                                         break;
 660                                 bch2_btree_iter_advance(&iter);
 661                         }
 662                         bch2_trans_iter_exit(trans, &iter);
 663
 664                         if (ret)
 665                                 return ret;
 666
 667                         --level;
 668                 }
 669         }
 670
 671         bch2_bkey_buf_exit(&last_flushed, c);
 672         return 0;
 673 }
 674
 675 static struct bpos bucket_pos_to_bp_safe(const struct bch_fs *c,
 676                                          struct bpos bucket)
 677 {
 678         return bch2_dev_exists2(c, bucket.inode)
 679                 ? bucket_pos_to_bp(c, bucket, 0)
 680                 : bucket;
 681 }
 682
 683 static int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 684                                         struct bpos start, struct bpos *end)
 685 {
 686         struct btree_iter alloc_iter;
 687         struct btree_iter bp_iter;
 688         struct bkey_s_c alloc_k, bp_k;
 689         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 690         bool alloc_end = false, bp_end = false;
 691         int ret = 0;
 692
 693         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 694                                   start, 0, 1, 0);
 695         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 696                                   bucket_pos_to_bp_safe(trans->c, start), 0, 1, 0);
 697         while (1) {
 698                 alloc_k = !alloc_end
 699                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 700                         : bkey_s_c_null;
 701                 bp_k = !bp_end
 702                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 703                         : bkey_s_c_null;
 704
 705                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 706                 if ((!alloc_k.k && !bp_k.k) || ret) {
 707                         *end = SPOS_MAX;
 708                         break;
 709                 }
 710
 711                 --btree_nodes;
 712                 if (!btree_nodes) {
 713                         *end = alloc_k.k ? alloc_k.k->p : SPOS_MAX;
 714                         break;
 715                 }
 716
 717                 if (bpos_lt(alloc_iter.pos, SPOS_MAX) &&
 718                     bpos_lt(bucket_pos_to_bp_safe(trans->c, alloc_iter.pos), bp_iter.pos)) {
 719                         if (!bch2_btree_iter_advance(&alloc_iter))
 720                                 alloc_end = true;
 721                 } else {
 722                         if (!bch2_btree_iter_advance(&bp_iter))
 723                                 bp_end = true;
 724                 }
 725         }
 726         bch2_trans_iter_exit(trans, &bp_iter);
 727         bch2_trans_iter_exit(trans, &alloc_iter);
 728         return ret;
 729 }
 730
 731 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 732 {
 733         struct btree_trans *trans = bch2_trans_get(c);
 734         struct bpos start = POS_MIN, end;
 735         int ret;
 736
 737         while (1) {
 738                 ret = bch2_get_alloc_in_memory_pos(trans, start, &end);
 739                 if (ret)
 740                         break;
 741
 742                 if (bpos_eq(start, POS_MIN) && !bpos_eq(end, SPOS_MAX))
 743                         bch_verbose(c, "%s(): alloc info does not fit in ram, running in multiple passes with %zu nodes per pass",
 744                                     __func__, btree_nodes_fit_in_ram(c));
 745
 746                 if (!bpos_eq(start, POS_MIN) || !bpos_eq(end, SPOS_MAX)) {
 747                         struct printbuf buf = PRINTBUF;
 748
 749                         prt_str(&buf, "check_extents_to_backpointers(): ");
 750                         bch2_bpos_to_text(&buf, start);
 751                         prt_str(&buf, "-");
 752                         bch2_bpos_to_text(&buf, end);
 753
 754                         bch_verbose(c, "%s", buf.buf);
 755                         printbuf_exit(&buf);
 756                 }
 757
 758                 ret = bch2_check_extents_to_backpointers_pass(trans, start, end);
 759                 if (ret || bpos_eq(end, SPOS_MAX))
 760                         break;
 761
 762                 start = bpos_successor(end);
 763         }
 764         bch2_trans_put(trans);
 765
 766         bch_err_fn(c, ret);
 767         return ret;
 768 }
 769
 770 static int check_one_backpointer(struct btree_trans *trans,
 771                                  struct bbpos start,
 772                                  struct bbpos end,
 773                                  struct bkey_s_c_backpointer bp,
 774                                  struct bpos *last_flushed_pos)
 775 {
 776         struct bch_fs *c = trans->c;
 777         struct btree_iter iter;
 778         struct bbpos pos = bp_to_bbpos(*bp.v);
 779         struct bkey_s_c k;
 780         struct printbuf buf = PRINTBUF;
 781         int ret;
 782
 783         if (bbpos_cmp(pos, start) < 0 ||
 784             bbpos_cmp(pos, end) > 0)
 785                 return 0;
 786
 787         k = bch2_backpointer_get_key(trans, &iter, bp.k->p, *bp.v, 0);
 788         ret = bkey_err(k);
 789         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 790                 return 0;
 791         if (ret)
 792                 return ret;
 793
 794         if (!k.k && !bpos_eq(*last_flushed_pos, bp.k->p)) {
 795                 *last_flushed_pos = bp.k->p;
 796                 ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 797                         -BCH_ERR_transaction_restart_write_buffer_flush;
 798                 goto out;
 799         }
 800
 801         if (fsck_err_on(!k.k, c,
 802                         backpointer_to_missing_ptr,
 803                         "backpointer for missing %s\n  %s",
 804                         bp.v->level ? "btree node" : "extent",
 805                         (bch2_bkey_val_to_text(&buf, c, bp.s_c), buf.buf))) {
 806                 ret = bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, bp.k->p);
 807                 goto out;
 808         }
 809 out:
 810 fsck_err:
 811         bch2_trans_iter_exit(trans, &iter);
 812         printbuf_exit(&buf);
 813         return ret;
 814 }
 815
 816 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
 817                                                    struct bbpos start,
 818                                                    struct bbpos end)
 819 {
 820         struct bpos last_flushed_pos = SPOS_MAX;
 821
 822         return for_each_btree_key_commit(trans, iter, BTREE_ID_backpointers,
 823                                   POS_MIN, BTREE_ITER_PREFETCH, k,
 824                                   NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 825                 check_one_backpointer(trans, start, end,
 826                                       bkey_s_c_to_backpointer(k),
 827                                       &last_flushed_pos));
 828 }
 829
 830 int bch2_check_backpointers_to_extents(struct bch_fs *c)
 831 {
 832         struct btree_trans *trans = bch2_trans_get(c);
 833         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
 834         int ret;
 835
 836         while (1) {
 837                 ret = bch2_get_btree_in_memory_pos(trans,
 838                                                    (1U << BTREE_ID_extents)|
 839                                                    (1U << BTREE_ID_reflink),
 840                                                    ~0,
 841                                                    start, &end);
 842                 if (ret)
 843                         break;
 844
 845                 if (!bbpos_cmp(start, BBPOS_MIN) &&
 846                     bbpos_cmp(end, BBPOS_MAX))
 847                         bch_verbose(c, "%s(): extents do not fit in ram, running in multiple passes with %zu nodes per pass",
 848                                     __func__, btree_nodes_fit_in_ram(c));
 849
 850                 if (bbpos_cmp(start, BBPOS_MIN) ||
 851                     bbpos_cmp(end, BBPOS_MAX)) {
 852                         struct printbuf buf = PRINTBUF;
 853
 854                         prt_str(&buf, "check_backpointers_to_extents(): ");
 855                         bch2_bbpos_to_text(&buf, start);
 856                         prt_str(&buf, "-");
 857                         bch2_bbpos_to_text(&buf, end);
 858
 859                         bch_verbose(c, "%s", buf.buf);
 860                         printbuf_exit(&buf);
 861                 }
 862
 863                 ret = bch2_check_backpointers_to_extents_pass(trans, start, end);
 864                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
 865                         break;
 866
 867                 start = bbpos_successor(end);
 868         }
 869         bch2_trans_put(trans);
 870
 871         bch_err_fn(c, ret);
 872         return ret;
 873 }