fs/bcachefs/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 bkey_i_backpointer *bp_k,
 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         int ret;
 147
 148         k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 149                                bp_k->k.p,
 150                                BTREE_ITER_INTENT|
 151                                BTREE_ITER_SLOTS|
 152                                BTREE_ITER_WITH_UPDATES);
 153         ret = bkey_err(k);
 154         if (ret)
 155                 goto err;
 156
 157         if (insert
 158             ? k.k->type
 159             : (k.k->type != KEY_TYPE_backpointer ||
 160                memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp)))) {
 161                 ret = backpointer_mod_err(trans, bp, k, orig_k, insert);
 162                 if (ret)
 163                         goto err;
 164         }
 165
 166         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 167 err:
 168         bch2_trans_iter_exit(trans, &bp_iter);
 169         return ret;
 170 }
 171
 172 /*
 173  * Find the next backpointer >= *bp_offset:
 174  */
 175 int bch2_get_next_backpointer(struct btree_trans *trans,
 176                               struct bpos bucket, int gen,
 177                               struct bpos *bp_pos,
 178                               struct bch_backpointer *bp,
 179                               unsigned iter_flags)
 180 {
 181         struct bch_fs *c = trans->c;
 182         struct bpos bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 183         struct btree_iter alloc_iter = { NULL }, bp_iter = { NULL };
 184         struct bkey_s_c k;
 185         int ret = 0;
 186
 187         if (bpos_ge(*bp_pos, bp_end_pos))
 188                 goto done;
 189
 190         if (gen >= 0) {
 191                 k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 192                                        bucket, BTREE_ITER_CACHED|iter_flags);
 193                 ret = bkey_err(k);
 194                 if (ret)
 195                         goto out;
 196
 197                 if (k.k->type != KEY_TYPE_alloc_v4 ||
 198                     bkey_s_c_to_alloc_v4(k).v->gen != gen)
 199                         goto done;
 200         }
 201
 202         *bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(c, bucket, 0));
 203
 204         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 205                                      *bp_pos, iter_flags, k, ret) {
 206                 if (bpos_ge(k.k->p, bp_end_pos))
 207                         break;
 208
 209                 *bp_pos = k.k->p;
 210                 *bp = *bkey_s_c_to_backpointer(k).v;
 211                 goto out;
 212         }
 213 done:
 214         *bp_pos = SPOS_MAX;
 215 out:
 216         bch2_trans_iter_exit(trans, &bp_iter);
 217         bch2_trans_iter_exit(trans, &alloc_iter);
 218         return ret;
 219 }
 220
 221 static void backpointer_not_found(struct btree_trans *trans,
 222                                   struct bpos bp_pos,
 223                                   struct bch_backpointer bp,
 224                                   struct bkey_s_c k)
 225 {
 226         struct bch_fs *c = trans->c;
 227         struct printbuf buf = PRINTBUF;
 228         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 229
 230         /*
 231          * If we're using the btree write buffer, the backpointer we were
 232          * looking at may have already been deleted - failure to find what it
 233          * pointed to is not an error:
 234          */
 235         if (likely(!bch2_backpointers_no_use_write_buffer))
 236                 return;
 237
 238         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 239                    bp.level ? "btree node" : "extent");
 240         prt_printf(&buf, "bucket: ");
 241         bch2_bpos_to_text(&buf, bucket);
 242         prt_printf(&buf, "\n  ");
 243
 244         prt_printf(&buf, "backpointer pos: ");
 245         bch2_bpos_to_text(&buf, bp_pos);
 246         prt_printf(&buf, "\n  ");
 247
 248         bch2_backpointer_to_text(&buf, &bp);
 249         prt_printf(&buf, "\n  ");
 250         bch2_bkey_val_to_text(&buf, c, k);
 251         if (c->curr_recovery_pass >= BCH_RECOVERY_PASS_check_extents_to_backpointers)
 252                 bch_err_ratelimited(c, "%s", buf.buf);
 253         else
 254                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 255
 256         printbuf_exit(&buf);
 257 }
 258
 259 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 260                                          struct btree_iter *iter,
 261                                          struct bpos bp_pos,
 262                                          struct bch_backpointer bp,
 263                                          unsigned iter_flags)
 264 {
 265         if (likely(!bp.level)) {
 266                 struct bch_fs *c = trans->c;
 267                 struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 268                 struct bkey_s_c k;
 269
 270                 bch2_trans_node_iter_init(trans, iter,
 271                                           bp.btree_id,
 272                                           bp.pos,
 273                                           0, 0,
 274                                           iter_flags);
 275                 k = bch2_btree_iter_peek_slot(iter);
 276                 if (bkey_err(k)) {
 277                         bch2_trans_iter_exit(trans, iter);
 278                         return k;
 279                 }
 280
 281                 if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 282                         return k;
 283
 284                 bch2_trans_iter_exit(trans, iter);
 285                 backpointer_not_found(trans, bp_pos, bp, k);
 286                 return bkey_s_c_null;
 287         } else {
 288                 struct btree *b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
 289
 290                 if (IS_ERR_OR_NULL(b)) {
 291                         bch2_trans_iter_exit(trans, iter);
 292                         return IS_ERR(b) ? bkey_s_c_err(PTR_ERR(b)) : bkey_s_c_null;
 293                 }
 294                 return bkey_i_to_s_c(&b->key);
 295         }
 296 }
 297
 298 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 299                                         struct btree_iter *iter,
 300                                         struct bpos bp_pos,
 301                                         struct bch_backpointer bp)
 302 {
 303         struct bch_fs *c = trans->c;
 304         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 305         struct btree *b;
 306
 307         BUG_ON(!bp.level);
 308
 309         bch2_trans_node_iter_init(trans, iter,
 310                                   bp.btree_id,
 311                                   bp.pos,
 312                                   0,
 313                                   bp.level - 1,
 314                                   0);
 315         b = bch2_btree_iter_peek_node(iter);
 316         if (IS_ERR(b))
 317                 goto err;
 318
 319         BUG_ON(b->c.level != bp.level - 1);
 320
 321         if (b && extent_matches_bp(c, bp.btree_id, bp.level,
 322                                    bkey_i_to_s_c(&b->key),
 323                                    bucket, bp))
 324                 return b;
 325
 326         if (b && btree_node_will_make_reachable(b)) {
 327                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 328         } else {
 329                 backpointer_not_found(trans, bp_pos, bp, bkey_i_to_s_c(&b->key));
 330                 b = NULL;
 331         }
 332 err:
 333         bch2_trans_iter_exit(trans, iter);
 334         return b;
 335 }
 336
 337 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 338                                         struct bkey_s_c k)
 339 {
 340         struct bch_fs *c = trans->c;
 341         struct btree_iter alloc_iter = { NULL };
 342         struct bkey_s_c alloc_k;
 343         struct printbuf buf = PRINTBUF;
 344         int ret = 0;
 345
 346         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 347                         backpointer_to_missing_device,
 348                         "backpointer for missing device:\n%s",
 349                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 350                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 351                 goto out;
 352         }
 353
 354         alloc_k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 355                                      bp_pos_to_bucket(c, k.k->p), 0);
 356         ret = bkey_err(alloc_k);
 357         if (ret)
 358                 goto out;
 359
 360         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 361                         backpointer_to_missing_alloc,
 362                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 363                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 364                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 365                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 366                 goto out;
 367         }
 368 out:
 369 fsck_err:
 370         bch2_trans_iter_exit(trans, &alloc_iter);
 371         printbuf_exit(&buf);
 372         return ret;
 373 }
 374
 375 /* verify that every backpointer has a corresponding alloc key */
 376 int bch2_check_btree_backpointers(struct bch_fs *c)
 377 {
 378         struct btree_iter iter;
 379         struct bkey_s_c k;
 380         int ret;
 381
 382         ret = bch2_trans_run(c,
 383                 for_each_btree_key_commit(trans, iter,
 384                         BTREE_ID_backpointers, POS_MIN, 0, k,
 385                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 386                   bch2_check_btree_backpointer(trans, &iter, k)));
 387         if (ret)
 388                 bch_err_fn(c, ret);
 389         return ret;
 390 }
 391
 392 struct bpos_level {
 393         unsigned        level;
 394         struct bpos     pos;
 395 };
 396
 397 static int check_bp_exists(struct btree_trans *trans,
 398                            struct bpos bucket,
 399                            struct bch_backpointer bp,
 400                            struct bkey_s_c orig_k,
 401                            struct bpos bucket_start,
 402                            struct bpos bucket_end,
 403                            struct bpos_level *last_flushed)
 404 {
 405         struct bch_fs *c = trans->c;
 406         struct btree_iter bp_iter = { NULL };
 407         struct printbuf buf = PRINTBUF;
 408         struct bkey_s_c bp_k;
 409         int ret;
 410
 411         if (bpos_lt(bucket, bucket_start) ||
 412             bpos_gt(bucket, bucket_end))
 413                 return 0;
 414
 415         if (!bch2_dev_bucket_exists(c, bucket))
 416                 goto missing;
 417
 418         bp_k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 419                                   bucket_pos_to_bp(c, bucket, bp.bucket_offset),
 420                                   0);
 421         ret = bkey_err(bp_k);
 422         if (ret)
 423                 goto err;
 424
 425         if (bp_k.k->type != KEY_TYPE_backpointer ||
 426             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
 427                 if (last_flushed->level != bp.level ||
 428                     !bpos_eq(last_flushed->pos, orig_k.k->p)) {
 429                         last_flushed->level = bp.level;
 430                         last_flushed->pos = orig_k.k->p;
 431
 432                         ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 433                                 -BCH_ERR_transaction_restart_write_buffer_flush;
 434                         goto out;
 435                 }
 436                 goto missing;
 437         }
 438 out:
 439 err:
 440 fsck_err:
 441         bch2_trans_iter_exit(trans, &bp_iter);
 442         printbuf_exit(&buf);
 443         return ret;
 444 missing:
 445         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 446                bch2_btree_id_str(bp.btree_id), bp.level);
 447         bch2_bkey_val_to_text(&buf, c, orig_k);
 448         prt_printf(&buf, "\nbp pos ");
 449         bch2_bpos_to_text(&buf, bp_iter.pos);
 450
 451         if (c->sb.version_upgrade_complete < bcachefs_metadata_version_backpointers ||
 452             c->opts.reconstruct_alloc ||
 453             fsck_err(c, ptr_to_missing_backpointer, "%s", buf.buf))
 454                 ret = bch2_bucket_backpointer_mod(trans, bucket, bp, orig_k, true);
 455
 456         goto out;
 457 }
 458
 459 static int check_extent_to_backpointers(struct btree_trans *trans,
 460                                         struct btree_iter *iter,
 461                                         struct bpos bucket_start,
 462                                         struct bpos bucket_end,
 463                                         struct bpos_level *last_flushed)
 464 {
 465         struct bch_fs *c = trans->c;
 466         struct bkey_ptrs_c ptrs;
 467         const union bch_extent_entry *entry;
 468         struct extent_ptr_decoded p;
 469         struct bkey_s_c k;
 470         int ret;
 471
 472         k = bch2_btree_iter_peek_all_levels(iter);
 473         ret = bkey_err(k);
 474         if (ret)
 475                 return ret;
 476         if (!k.k)
 477                 return 0;
 478
 479         ptrs = bch2_bkey_ptrs_c(k);
 480         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 481                 struct bpos bucket_pos;
 482                 struct bch_backpointer bp;
 483
 484                 if (p.ptr.cached)
 485                         continue;
 486
 487                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 488                                       k, p, &bucket_pos, &bp);
 489
 490                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 491                                       bucket_start, bucket_end,
 492                                       last_flushed);
 493                 if (ret)
 494                         return ret;
 495         }
 496
 497         return 0;
 498 }
 499
 500 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 501                                             enum btree_id btree_id,
 502                                             struct bpos bucket_start,
 503                                             struct bpos bucket_end,
 504                                             struct bpos_level *last_flushed)
 505 {
 506         struct bch_fs *c = trans->c;
 507         struct btree_root *r = bch2_btree_id_root(c, btree_id);
 508         struct btree_iter iter;
 509         struct btree *b;
 510         struct bkey_s_c k;
 511         struct bkey_ptrs_c ptrs;
 512         struct extent_ptr_decoded p;
 513         const union bch_extent_entry *entry;
 514         int ret;
 515
 516         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0, r->level, 0);
 517         b = bch2_btree_iter_peek_node(&iter);
 518         ret = PTR_ERR_OR_ZERO(b);
 519         if (ret)
 520                 goto err;
 521
 522         BUG_ON(b != btree_node_root(c, b));
 523
 524         k = bkey_i_to_s_c(&b->key);
 525         ptrs = bch2_bkey_ptrs_c(k);
 526         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 527                 struct bpos bucket_pos;
 528                 struct bch_backpointer bp;
 529
 530                 if (p.ptr.cached)
 531                         continue;
 532
 533                 bch2_extent_ptr_to_bp(c, iter.btree_id, b->c.level + 1,
 534                                       k, p, &bucket_pos, &bp);
 535
 536                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 537                                       bucket_start, bucket_end,
 538                                       last_flushed);
 539                 if (ret)
 540                         goto err;
 541         }
 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 bpos_level last_flushed = { UINT_MAX, POS_MIN };
 620         int ret = 0;
 621
 622         for (btree_id = 0; btree_id < btree_id_nr_alive(c); btree_id++) {
 623                 unsigned depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 624
 625                 bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 626                                           depth,
 627                                           BTREE_ITER_ALL_LEVELS|
 628                                           BTREE_ITER_PREFETCH);
 629
 630                 do {
 631                         ret = commit_do(trans, NULL, NULL,
 632                                         BTREE_INSERT_LAZY_RW|
 633                                         BTREE_INSERT_NOFAIL,
 634                                         check_extent_to_backpointers(trans, &iter,
 635                                                                 bucket_start, bucket_end,
 636                                                                 &last_flushed));
 637                         if (ret)
 638                                 break;
 639                 } while (!bch2_btree_iter_advance(&iter));
 640
 641                 bch2_trans_iter_exit(trans, &iter);
 642
 643                 if (ret)
 644                         break;
 645
 646                 ret = commit_do(trans, NULL, NULL,
 647                                 BTREE_INSERT_LAZY_RW|
 648                                 BTREE_INSERT_NOFAIL,
 649                                 check_btree_root_to_backpointers(trans, btree_id,
 650                                                         bucket_start, bucket_end,
 651                                                         &last_flushed));
 652                 if (ret)
 653                         break;
 654         }
 655         return ret;
 656 }
 657
 658 static struct bpos bucket_pos_to_bp_safe(const struct bch_fs *c,
 659                                          struct bpos bucket)
 660 {
 661         return bch2_dev_exists2(c, bucket.inode)
 662                 ? bucket_pos_to_bp(c, bucket, 0)
 663                 : bucket;
 664 }
 665
 666 static int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 667                                         struct bpos start, struct bpos *end)
 668 {
 669         struct btree_iter alloc_iter;
 670         struct btree_iter bp_iter;
 671         struct bkey_s_c alloc_k, bp_k;
 672         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 673         bool alloc_end = false, bp_end = false;
 674         int ret = 0;
 675
 676         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 677                                   start, 0, 1, 0);
 678         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 679                                   bucket_pos_to_bp_safe(trans->c, start), 0, 1, 0);
 680         while (1) {
 681                 alloc_k = !alloc_end
 682                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 683                         : bkey_s_c_null;
 684                 bp_k = !bp_end
 685                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 686                         : bkey_s_c_null;
 687
 688                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 689                 if ((!alloc_k.k && !bp_k.k) || ret) {
 690                         *end = SPOS_MAX;
 691                         break;
 692                 }
 693
 694                 --btree_nodes;
 695                 if (!btree_nodes) {
 696                         *end = alloc_k.k ? alloc_k.k->p : SPOS_MAX;
 697                         break;
 698                 }
 699
 700                 if (bpos_lt(alloc_iter.pos, SPOS_MAX) &&
 701                     bpos_lt(bucket_pos_to_bp_safe(trans->c, alloc_iter.pos), bp_iter.pos)) {
 702                         if (!bch2_btree_iter_advance(&alloc_iter))
 703                                 alloc_end = true;
 704                 } else {
 705                         if (!bch2_btree_iter_advance(&bp_iter))
 706                                 bp_end = true;
 707                 }
 708         }
 709         bch2_trans_iter_exit(trans, &bp_iter);
 710         bch2_trans_iter_exit(trans, &alloc_iter);
 711         return ret;
 712 }
 713
 714 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 715 {
 716         struct btree_trans *trans = bch2_trans_get(c);
 717         struct bpos start = POS_MIN, end;
 718         int ret;
 719
 720         while (1) {
 721                 ret = bch2_get_alloc_in_memory_pos(trans, start, &end);
 722                 if (ret)
 723                         break;
 724
 725                 if (bpos_eq(start, POS_MIN) && !bpos_eq(end, SPOS_MAX))
 726                         bch_verbose(c, "%s(): alloc info does not fit in ram, running in multiple passes with %zu nodes per pass",
 727                                     __func__, btree_nodes_fit_in_ram(c));
 728
 729                 if (!bpos_eq(start, POS_MIN) || !bpos_eq(end, SPOS_MAX)) {
 730                         struct printbuf buf = PRINTBUF;
 731
 732                         prt_str(&buf, "check_extents_to_backpointers(): ");
 733                         bch2_bpos_to_text(&buf, start);
 734                         prt_str(&buf, "-");
 735                         bch2_bpos_to_text(&buf, end);
 736
 737                         bch_verbose(c, "%s", buf.buf);
 738                         printbuf_exit(&buf);
 739                 }
 740
 741                 ret = bch2_check_extents_to_backpointers_pass(trans, start, end);
 742                 if (ret || bpos_eq(end, SPOS_MAX))
 743                         break;
 744
 745                 start = bpos_successor(end);
 746         }
 747         bch2_trans_put(trans);
 748
 749         if (ret)
 750                 bch_err_fn(c, ret);
 751         return ret;
 752 }
 753
 754 static int check_one_backpointer(struct btree_trans *trans,
 755                                  struct bbpos start,
 756                                  struct bbpos end,
 757                                  struct bkey_s_c_backpointer bp,
 758                                  struct bpos *last_flushed_pos)
 759 {
 760         struct bch_fs *c = trans->c;
 761         struct btree_iter iter;
 762         struct bbpos pos = bp_to_bbpos(*bp.v);
 763         struct bkey_s_c k;
 764         struct printbuf buf = PRINTBUF;
 765         int ret;
 766
 767         if (bbpos_cmp(pos, start) < 0 ||
 768             bbpos_cmp(pos, end) > 0)
 769                 return 0;
 770
 771         k = bch2_backpointer_get_key(trans, &iter, bp.k->p, *bp.v, 0);
 772         ret = bkey_err(k);
 773         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 774                 return 0;
 775         if (ret)
 776                 return ret;
 777
 778         if (!k.k && !bpos_eq(*last_flushed_pos, bp.k->p)) {
 779                 *last_flushed_pos = bp.k->p;
 780                 ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 781                         -BCH_ERR_transaction_restart_write_buffer_flush;
 782                 goto out;
 783         }
 784
 785         if (fsck_err_on(!k.k, c,
 786                         backpointer_to_missing_ptr,
 787                         "backpointer for missing %s\n  %s",
 788                         bp.v->level ? "btree node" : "extent",
 789                         (bch2_bkey_val_to_text(&buf, c, bp.s_c), buf.buf))) {
 790                 ret = bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, bp.k->p);
 791                 goto out;
 792         }
 793 out:
 794 fsck_err:
 795         bch2_trans_iter_exit(trans, &iter);
 796         printbuf_exit(&buf);
 797         return ret;
 798 }
 799
 800 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
 801                                                    struct bbpos start,
 802                                                    struct bbpos end)
 803 {
 804         struct btree_iter iter;
 805         struct bkey_s_c k;
 806         struct bpos last_flushed_pos = SPOS_MAX;
 807
 808         return for_each_btree_key_commit(trans, iter, BTREE_ID_backpointers,
 809                                   POS_MIN, BTREE_ITER_PREFETCH, k,
 810                                   NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 811                 check_one_backpointer(trans, start, end,
 812                                       bkey_s_c_to_backpointer(k),
 813                                       &last_flushed_pos));
 814 }
 815
 816 int bch2_check_backpointers_to_extents(struct bch_fs *c)
 817 {
 818         struct btree_trans *trans = bch2_trans_get(c);
 819         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
 820         int ret;
 821
 822         while (1) {
 823                 ret = bch2_get_btree_in_memory_pos(trans,
 824                                                    (1U << BTREE_ID_extents)|
 825                                                    (1U << BTREE_ID_reflink),
 826                                                    ~0,
 827                                                    start, &end);
 828                 if (ret)
 829                         break;
 830
 831                 if (!bbpos_cmp(start, BBPOS_MIN) &&
 832                     bbpos_cmp(end, BBPOS_MAX))
 833                         bch_verbose(c, "%s(): extents do not fit in ram, running in multiple passes with %zu nodes per pass",
 834                                     __func__, btree_nodes_fit_in_ram(c));
 835
 836                 if (bbpos_cmp(start, BBPOS_MIN) ||
 837                     bbpos_cmp(end, BBPOS_MAX)) {
 838                         struct printbuf buf = PRINTBUF;
 839
 840                         prt_str(&buf, "check_backpointers_to_extents(): ");
 841                         bch2_bbpos_to_text(&buf, start);
 842                         prt_str(&buf, "-");
 843                         bch2_bbpos_to_text(&buf, end);
 844
 845                         bch_verbose(c, "%s", buf.buf);
 846                         printbuf_exit(&buf);
 847                 }
 848
 849                 ret = bch2_check_backpointers_to_extents_pass(trans, start, end);
 850                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
 851                         break;
 852
 853                 start = bbpos_successor(end);
 854         }
 855         bch2_trans_put(trans);
 856
 857         if (ret)
 858                 bch_err_fn(c, ret);
 859         return ret;
 860 }