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_write_buffer.h"
   9 #include "error.h"
  10
  11 #include <linux/mm.h>
  12
  13 static bool extent_matches_bp(struct bch_fs *c,
  14                               enum btree_id btree_id, unsigned level,
  15                               struct bkey_s_c k,
  16                               struct bpos bucket,
  17                               struct bch_backpointer bp)
  18 {
  19         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  20         const union bch_extent_entry *entry;
  21         struct extent_ptr_decoded p;
  22
  23         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  24                 struct bpos bucket2;
  25                 struct bch_backpointer bp2;
  26
  27                 if (p.ptr.cached)
  28                         continue;
  29
  30                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  31                                       &bucket2, &bp2);
  32                 if (bpos_eq(bucket, bucket2) &&
  33                     !memcmp(&bp, &bp2, sizeof(bp)))
  34                         return true;
  35         }
  36
  37         return false;
  38 }
  39
  40 int bch2_backpointer_invalid(const struct bch_fs *c, struct bkey_s_c k,
  41                              enum bkey_invalid_flags flags,
  42                              struct printbuf *err)
  43 {
  44         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  45         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  46
  47         if (!bpos_eq(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset))) {
  48                 prt_str(err, "backpointer at wrong pos");
  49                 return -BCH_ERR_invalid_bkey;
  50         }
  51
  52         return 0;
  53 }
  54
  55 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
  56 {
  57         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
  58                bch2_btree_ids[bp->btree_id],
  59                bp->level,
  60                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  61                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  62                bp->bucket_len);
  63         bch2_bpos_to_text(out, bp->pos);
  64 }
  65
  66 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
  67 {
  68         prt_str(out, "bucket=");
  69         bch2_bpos_to_text(out, bp_pos_to_bucket(c, k.k->p));
  70         prt_str(out, " ");
  71
  72         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
  73 }
  74
  75 void bch2_backpointer_swab(struct bkey_s k)
  76 {
  77         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
  78
  79         bp.v->bucket_offset     = swab32(bp.v->bucket_offset);
  80         bp.v->bucket_len        = swab32(bp.v->bucket_len);
  81         bch2_bpos_swab(&bp.v->pos);
  82 }
  83
  84 static noinline int backpointer_mod_err(struct btree_trans *trans,
  85                                         struct bch_backpointer bp,
  86                                         struct bkey_s_c bp_k,
  87                                         struct bkey_s_c orig_k,
  88                                         bool insert)
  89 {
  90         struct bch_fs *c = trans->c;
  91         struct printbuf buf = PRINTBUF;
  92
  93         if (insert) {
  94                 prt_printf(&buf, "existing backpointer found when inserting ");
  95                 bch2_backpointer_to_text(&buf, &bp);
  96                 prt_newline(&buf);
  97                 printbuf_indent_add(&buf, 2);
  98
  99                 prt_printf(&buf, "found ");
 100                 bch2_bkey_val_to_text(&buf, c, bp_k);
 101                 prt_newline(&buf);
 102
 103                 prt_printf(&buf, "for ");
 104                 bch2_bkey_val_to_text(&buf, c, orig_k);
 105
 106                 bch_err(c, "%s", buf.buf);
 107         } else if (c->curr_recovery_pass > BCH_RECOVERY_PASS_check_extents_to_backpointers) {
 108                 prt_printf(&buf, "backpointer not found when deleting");
 109                 prt_newline(&buf);
 110                 printbuf_indent_add(&buf, 2);
 111
 112                 prt_printf(&buf, "searching for ");
 113                 bch2_backpointer_to_text(&buf, &bp);
 114                 prt_newline(&buf);
 115
 116                 prt_printf(&buf, "got ");
 117                 bch2_bkey_val_to_text(&buf, c, bp_k);
 118                 prt_newline(&buf);
 119
 120                 prt_printf(&buf, "for ");
 121                 bch2_bkey_val_to_text(&buf, c, orig_k);
 122
 123                 bch_err(c, "%s", buf.buf);
 124         }
 125
 126         printbuf_exit(&buf);
 127
 128         if (c->curr_recovery_pass > BCH_RECOVERY_PASS_check_extents_to_backpointers) {
 129                 bch2_inconsistent_error(c);
 130                 return -EIO;
 131         } else {
 132                 return 0;
 133         }
 134 }
 135
 136 int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 137                                 struct bkey_i_backpointer *bp_k,
 138                                 struct bch_backpointer bp,
 139                                 struct bkey_s_c orig_k,
 140                                 bool insert)
 141 {
 142         struct btree_iter bp_iter;
 143         struct bkey_s_c k;
 144         int ret;
 145
 146         k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 147                                bp_k->k.p,
 148                                BTREE_ITER_INTENT|
 149                                BTREE_ITER_SLOTS|
 150                                BTREE_ITER_WITH_UPDATES);
 151         ret = bkey_err(k);
 152         if (ret)
 153                 goto err;
 154
 155         if (insert
 156             ? k.k->type
 157             : (k.k->type != KEY_TYPE_backpointer ||
 158                memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp)))) {
 159                 ret = backpointer_mod_err(trans, bp, k, orig_k, insert);
 160                 if (ret)
 161                         goto err;
 162         }
 163
 164         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 165 err:
 166         bch2_trans_iter_exit(trans, &bp_iter);
 167         return ret;
 168 }
 169
 170 /*
 171  * Find the next backpointer >= *bp_offset:
 172  */
 173 int bch2_get_next_backpointer(struct btree_trans *trans,
 174                               struct bpos bucket, int gen,
 175                               struct bpos *bp_pos,
 176                               struct bch_backpointer *bp,
 177                               unsigned iter_flags)
 178 {
 179         struct bch_fs *c = trans->c;
 180         struct bpos bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 181         struct btree_iter alloc_iter = { NULL }, bp_iter = { NULL };
 182         struct bkey_s_c k;
 183         int ret = 0;
 184
 185         if (bpos_ge(*bp_pos, bp_end_pos))
 186                 goto done;
 187
 188         if (gen >= 0) {
 189                 k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 190                                        bucket, BTREE_ITER_CACHED|iter_flags);
 191                 ret = bkey_err(k);
 192                 if (ret)
 193                         goto out;
 194
 195                 if (k.k->type != KEY_TYPE_alloc_v4 ||
 196                     bkey_s_c_to_alloc_v4(k).v->gen != gen)
 197                         goto done;
 198         }
 199
 200         *bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(c, bucket, 0));
 201
 202         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 203                                      *bp_pos, iter_flags, k, ret) {
 204                 if (bpos_ge(k.k->p, bp_end_pos))
 205                         break;
 206
 207                 *bp_pos = k.k->p;
 208                 *bp = *bkey_s_c_to_backpointer(k).v;
 209                 goto out;
 210         }
 211 done:
 212         *bp_pos = SPOS_MAX;
 213 out:
 214         bch2_trans_iter_exit(trans, &bp_iter);
 215         bch2_trans_iter_exit(trans, &alloc_iter);
 216         return ret;
 217 }
 218
 219 static void backpointer_not_found(struct btree_trans *trans,
 220                                   struct bpos bp_pos,
 221                                   struct bch_backpointer bp,
 222                                   struct bkey_s_c k,
 223                                   const char *thing_it_points_to)
 224 {
 225         struct bch_fs *c = trans->c;
 226         struct printbuf buf = PRINTBUF;
 227         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 228
 229         if (likely(!bch2_backpointers_no_use_write_buffer))
 230                 return;
 231
 232         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 233                    thing_it_points_to);
 234         prt_printf(&buf, "bucket: ");
 235         bch2_bpos_to_text(&buf, bucket);
 236         prt_printf(&buf, "\n  ");
 237
 238         prt_printf(&buf, "backpointer pos: ");
 239         bch2_bpos_to_text(&buf, bp_pos);
 240         prt_printf(&buf, "\n  ");
 241
 242         bch2_backpointer_to_text(&buf, &bp);
 243         prt_printf(&buf, "\n  ");
 244         bch2_bkey_val_to_text(&buf, c, k);
 245         if (c->curr_recovery_pass >= BCH_RECOVERY_PASS_check_extents_to_backpointers)
 246                 bch_err_ratelimited(c, "%s", buf.buf);
 247         else
 248                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 249
 250         printbuf_exit(&buf);
 251 }
 252
 253 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 254                                          struct btree_iter *iter,
 255                                          struct bpos bp_pos,
 256                                          struct bch_backpointer bp,
 257                                          unsigned iter_flags)
 258 {
 259         struct bch_fs *c = trans->c;
 260         struct btree_root *r = bch2_btree_id_root(c, bp.btree_id);
 261         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 262         struct bkey_s_c k;
 263
 264         bch2_trans_node_iter_init(trans, iter,
 265                                   bp.btree_id,
 266                                   bp.pos,
 267                                   0,
 268                                   min(bp.level, r->level),
 269                                   iter_flags);
 270         k = bch2_btree_iter_peek_slot(iter);
 271         if (bkey_err(k)) {
 272                 bch2_trans_iter_exit(trans, iter);
 273                 return k;
 274         }
 275
 276         if (bp.level == r->level + 1)
 277                 k = bkey_i_to_s_c(&r->key);
 278
 279         if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 280                 return k;
 281
 282         bch2_trans_iter_exit(trans, iter);
 283
 284         if (unlikely(bch2_backpointers_no_use_write_buffer)) {
 285                 if (bp.level) {
 286                         struct btree *b;
 287
 288                         /*
 289                          * If a backpointer for a btree node wasn't found, it may be
 290                          * because it was overwritten by a new btree node that hasn't
 291                          * been written out yet - backpointer_get_node() checks for
 292                          * this:
 293                          */
 294                         b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
 295                         if (!IS_ERR_OR_NULL(b))
 296                                 return bkey_i_to_s_c(&b->key);
 297
 298                         bch2_trans_iter_exit(trans, iter);
 299
 300                         if (IS_ERR(b))
 301                                 return bkey_s_c_err(PTR_ERR(b));
 302                         return bkey_s_c_null;
 303                 }
 304
 305                 backpointer_not_found(trans, bp_pos, bp, k, "extent");
 306         }
 307
 308         return bkey_s_c_null;
 309 }
 310
 311 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 312                                         struct btree_iter *iter,
 313                                         struct bpos bp_pos,
 314                                         struct bch_backpointer bp)
 315 {
 316         struct bch_fs *c = trans->c;
 317         struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 318         struct btree *b;
 319
 320         BUG_ON(!bp.level);
 321
 322         bch2_trans_node_iter_init(trans, iter,
 323                                   bp.btree_id,
 324                                   bp.pos,
 325                                   0,
 326                                   bp.level - 1,
 327                                   0);
 328         b = bch2_btree_iter_peek_node(iter);
 329         if (IS_ERR(b))
 330                 goto err;
 331
 332         if (b && extent_matches_bp(c, bp.btree_id, bp.level,
 333                                    bkey_i_to_s_c(&b->key),
 334                                    bucket, bp))
 335                 return b;
 336
 337         if (b && btree_node_will_make_reachable(b)) {
 338                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 339         } else {
 340                 backpointer_not_found(trans, bp_pos, bp,
 341                                       bkey_i_to_s_c(&b->key), "btree node");
 342                 b = NULL;
 343         }
 344 err:
 345         bch2_trans_iter_exit(trans, iter);
 346         return b;
 347 }
 348
 349 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 350                                         struct bkey_s_c k)
 351 {
 352         struct bch_fs *c = trans->c;
 353         struct btree_iter alloc_iter = { NULL };
 354         struct bch_dev *ca;
 355         struct bkey_s_c alloc_k;
 356         struct printbuf buf = PRINTBUF;
 357         int ret = 0;
 358
 359         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 360                         "backpointer for mising device:\n%s",
 361                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 362                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 363                 goto out;
 364         }
 365
 366         ca = bch_dev_bkey_exists(c, k.k->p.inode);
 367
 368         alloc_k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
 369                                      bp_pos_to_bucket(c, k.k->p), 0);
 370         ret = bkey_err(alloc_k);
 371         if (ret)
 372                 goto out;
 373
 374         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 375                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 376                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 377                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 378                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 379                 goto out;
 380         }
 381 out:
 382 fsck_err:
 383         bch2_trans_iter_exit(trans, &alloc_iter);
 384         printbuf_exit(&buf);
 385         return ret;
 386 }
 387
 388 /* verify that every backpointer has a corresponding alloc key */
 389 int bch2_check_btree_backpointers(struct bch_fs *c)
 390 {
 391         struct btree_iter iter;
 392         struct bkey_s_c k;
 393         int ret;
 394
 395         ret = bch2_trans_run(c,
 396                 for_each_btree_key_commit(&trans, iter,
 397                         BTREE_ID_backpointers, POS_MIN, 0, k,
 398                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 399                   bch2_check_btree_backpointer(&trans, &iter, k)));
 400         if (ret)
 401                 bch_err_fn(c, ret);
 402         return ret;
 403 }
 404
 405 struct bpos_level {
 406         unsigned        level;
 407         struct bpos     pos;
 408 };
 409
 410 static int check_bp_exists(struct btree_trans *trans,
 411                            struct bpos bucket,
 412                            struct bch_backpointer bp,
 413                            struct bkey_s_c orig_k,
 414                            struct bpos bucket_start,
 415                            struct bpos bucket_end,
 416                            struct bpos_level *last_flushed)
 417 {
 418         struct bch_fs *c = trans->c;
 419         struct btree_iter bp_iter = { NULL };
 420         struct printbuf buf = PRINTBUF;
 421         struct bkey_s_c bp_k;
 422         int ret;
 423
 424         if (bpos_lt(bucket, bucket_start) ||
 425             bpos_gt(bucket, bucket_end))
 426                 return 0;
 427
 428         if (!bch2_dev_bucket_exists(c, bucket))
 429                 goto missing;
 430
 431         bp_k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
 432                                   bucket_pos_to_bp(c, bucket, bp.bucket_offset),
 433                                   0);
 434         ret = bkey_err(bp_k);
 435         if (ret)
 436                 goto err;
 437
 438         if (bp_k.k->type != KEY_TYPE_backpointer ||
 439             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
 440                 if (last_flushed->level != bp.level ||
 441                     !bpos_eq(last_flushed->pos, orig_k.k->p)) {
 442                         last_flushed->level = bp.level;
 443                         last_flushed->pos = orig_k.k->p;
 444
 445                         ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 446                                 -BCH_ERR_transaction_restart_write_buffer_flush;
 447                         goto out;
 448                 }
 449                 goto missing;
 450         }
 451 out:
 452 err:
 453 fsck_err:
 454         bch2_trans_iter_exit(trans, &bp_iter);
 455         printbuf_exit(&buf);
 456         return ret;
 457 missing:
 458         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 459                bch2_btree_ids[bp.btree_id], bp.level);
 460         bch2_bkey_val_to_text(&buf, c, orig_k);
 461         prt_printf(&buf, "\nbp pos ");
 462         bch2_bpos_to_text(&buf, bp_iter.pos);
 463
 464         if (c->sb.version_upgrade_complete < bcachefs_metadata_version_backpointers ||
 465             c->opts.reconstruct_alloc ||
 466             fsck_err(c, "%s", buf.buf))
 467                 ret = bch2_bucket_backpointer_mod(trans, bucket, bp, orig_k, true);
 468
 469         goto out;
 470 }
 471
 472 static int check_extent_to_backpointers(struct btree_trans *trans,
 473                                         struct btree_iter *iter,
 474                                         struct bpos bucket_start,
 475                                         struct bpos bucket_end,
 476                                         struct bpos_level *last_flushed)
 477 {
 478         struct bch_fs *c = trans->c;
 479         struct bkey_ptrs_c ptrs;
 480         const union bch_extent_entry *entry;
 481         struct extent_ptr_decoded p;
 482         struct bkey_s_c k;
 483         int ret;
 484
 485         k = bch2_btree_iter_peek_all_levels(iter);
 486         ret = bkey_err(k);
 487         if (ret)
 488                 return ret;
 489         if (!k.k)
 490                 return 0;
 491
 492         ptrs = bch2_bkey_ptrs_c(k);
 493         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 494                 struct bpos bucket_pos;
 495                 struct bch_backpointer bp;
 496
 497                 if (p.ptr.cached)
 498                         continue;
 499
 500                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 501                                       k, p, &bucket_pos, &bp);
 502
 503                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 504                                       bucket_start, bucket_end,
 505                                       last_flushed);
 506                 if (ret)
 507                         return ret;
 508         }
 509
 510         return 0;
 511 }
 512
 513 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 514                                             enum btree_id btree_id,
 515                                             struct bpos bucket_start,
 516                                             struct bpos bucket_end,
 517                                             struct bpos_level *last_flushed)
 518 {
 519         struct bch_fs *c = trans->c;
 520         struct btree_root *r = bch2_btree_id_root(c, btree_id);
 521         struct btree_iter iter;
 522         struct btree *b;
 523         struct bkey_s_c k;
 524         struct bkey_ptrs_c ptrs;
 525         struct extent_ptr_decoded p;
 526         const union bch_extent_entry *entry;
 527         int ret;
 528
 529         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0, r->level, 0);
 530         b = bch2_btree_iter_peek_node(&iter);
 531         ret = PTR_ERR_OR_ZERO(b);
 532         if (ret)
 533                 goto err;
 534
 535         BUG_ON(b != btree_node_root(c, b));
 536
 537         k = bkey_i_to_s_c(&b->key);
 538         ptrs = bch2_bkey_ptrs_c(k);
 539         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 540                 struct bpos bucket_pos;
 541                 struct bch_backpointer bp;
 542
 543                 if (p.ptr.cached)
 544                         continue;
 545
 546                 bch2_extent_ptr_to_bp(c, iter.btree_id, b->c.level + 1,
 547                                       k, p, &bucket_pos, &bp);
 548
 549                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 550                                       bucket_start, bucket_end,
 551                                       last_flushed);
 552                 if (ret)
 553                         goto err;
 554         }
 555 err:
 556         bch2_trans_iter_exit(trans, &iter);
 557         return ret;
 558 }
 559
 560 static inline struct bbpos bp_to_bbpos(struct bch_backpointer bp)
 561 {
 562         return (struct bbpos) {
 563                 .btree  = bp.btree_id,
 564                 .pos    = bp.pos,
 565         };
 566 }
 567
 568 static size_t btree_nodes_fit_in_ram(struct bch_fs *c)
 569 {
 570         struct sysinfo i;
 571         u64 mem_bytes;
 572
 573         si_meminfo(&i);
 574         mem_bytes = i.totalram * i.mem_unit;
 575         return div_u64(mem_bytes >> 1, btree_bytes(c));
 576 }
 577
 578 static int bch2_get_btree_in_memory_pos(struct btree_trans *trans,
 579                                         unsigned btree_leaf_mask,
 580                                         unsigned btree_interior_mask,
 581                                         struct bbpos start, struct bbpos *end)
 582 {
 583         struct btree_iter iter;
 584         struct bkey_s_c k;
 585         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 586         enum btree_id btree;
 587         int ret = 0;
 588
 589         for (btree = start.btree; btree < BTREE_ID_NR && !ret; btree++) {
 590                 unsigned depth = ((1U << btree) & btree_leaf_mask) ? 1 : 2;
 591
 592                 if (!((1U << btree) & btree_leaf_mask) &&
 593                     !((1U << btree) & btree_interior_mask))
 594                         continue;
 595
 596                 bch2_trans_node_iter_init(trans, &iter, btree,
 597                                           btree == start.btree ? start.pos : POS_MIN,
 598                                           0, depth, 0);
 599                 /*
 600                  * for_each_btree_key_contineu() doesn't check the return value
 601                  * from bch2_btree_iter_advance(), which is needed when
 602                  * iterating over interior nodes where we'll see keys at
 603                  * SPOS_MAX:
 604                  */
 605                 do {
 606                         k = __bch2_btree_iter_peek_and_restart(trans, &iter, 0);
 607                         ret = bkey_err(k);
 608                         if (!k.k || ret)
 609                                 break;
 610
 611                         --btree_nodes;
 612                         if (!btree_nodes) {
 613                                 *end = BBPOS(btree, k.k->p);
 614                                 bch2_trans_iter_exit(trans, &iter);
 615                                 return 0;
 616                         }
 617                 } while (bch2_btree_iter_advance(&iter));
 618                 bch2_trans_iter_exit(trans, &iter);
 619         }
 620
 621         *end = BBPOS_MAX;
 622         return ret;
 623 }
 624
 625 static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 626                                                    struct bpos bucket_start,
 627                                                    struct bpos bucket_end)
 628 {
 629         struct bch_fs *c = trans->c;
 630         struct btree_iter iter;
 631         enum btree_id btree_id;
 632         struct bpos_level last_flushed = { UINT_MAX };
 633         int ret = 0;
 634
 635         for (btree_id = 0; btree_id < btree_id_nr_alive(c); btree_id++) {
 636                 unsigned depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 637
 638                 bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 639                                           depth,
 640                                           BTREE_ITER_ALL_LEVELS|
 641                                           BTREE_ITER_PREFETCH);
 642
 643                 do {
 644                         ret = commit_do(trans, NULL, NULL,
 645                                         BTREE_INSERT_LAZY_RW|
 646                                         BTREE_INSERT_NOFAIL,
 647                                         check_extent_to_backpointers(trans, &iter,
 648                                                                 bucket_start, bucket_end,
 649                                                                 &last_flushed));
 650                         if (ret)
 651                                 break;
 652                 } while (!bch2_btree_iter_advance(&iter));
 653
 654                 bch2_trans_iter_exit(trans, &iter);
 655
 656                 if (ret)
 657                         break;
 658
 659                 ret = commit_do(trans, NULL, NULL,
 660                                 BTREE_INSERT_LAZY_RW|
 661                                 BTREE_INSERT_NOFAIL,
 662                                 check_btree_root_to_backpointers(trans, btree_id,
 663                                                         bucket_start, bucket_end,
 664                                                         &last_flushed));
 665                 if (ret)
 666                         break;
 667         }
 668         return ret;
 669 }
 670
 671 static struct bpos bucket_pos_to_bp_safe(const struct bch_fs *c,
 672                                          struct bpos bucket)
 673 {
 674         return bch2_dev_exists2(c, bucket.inode)
 675                 ? bucket_pos_to_bp(c, bucket, 0)
 676                 : bucket;
 677 }
 678
 679 static int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 680                                         struct bpos start, struct bpos *end)
 681 {
 682         struct btree_iter alloc_iter;
 683         struct btree_iter bp_iter;
 684         struct bkey_s_c alloc_k, bp_k;
 685         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 686         bool alloc_end = false, bp_end = false;
 687         int ret = 0;
 688
 689         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 690                                   start, 0, 1, 0);
 691         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 692                                   bucket_pos_to_bp_safe(trans->c, start), 0, 1, 0);
 693         while (1) {
 694                 alloc_k = !alloc_end
 695                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 696                         : bkey_s_c_null;
 697                 bp_k = !bp_end
 698                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 699                         : bkey_s_c_null;
 700
 701                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 702                 if ((!alloc_k.k && !bp_k.k) || ret) {
 703                         *end = SPOS_MAX;
 704                         break;
 705                 }
 706
 707                 --btree_nodes;
 708                 if (!btree_nodes) {
 709                         *end = alloc_k.k->p;
 710                         break;
 711                 }
 712
 713                 if (bpos_lt(alloc_iter.pos, SPOS_MAX) &&
 714                     bpos_lt(bucket_pos_to_bp_safe(trans->c, alloc_iter.pos), bp_iter.pos)) {
 715                         if (!bch2_btree_iter_advance(&alloc_iter))
 716                                 alloc_end = true;
 717                 } else {
 718                         if (!bch2_btree_iter_advance(&bp_iter))
 719                                 bp_end = true;
 720                 }
 721         }
 722         bch2_trans_iter_exit(trans, &bp_iter);
 723         bch2_trans_iter_exit(trans, &alloc_iter);
 724         return ret;
 725 }
 726
 727 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 728 {
 729         struct btree_trans trans;
 730         struct bpos start = POS_MIN, end;
 731         int ret;
 732
 733         bch2_trans_init(&trans, c, 0, 0);
 734         while (1) {
 735                 ret = bch2_get_alloc_in_memory_pos(&trans, start, &end);
 736                 if (ret)
 737                         break;
 738
 739                 if (bpos_eq(start, POS_MIN) && !bpos_eq(end, SPOS_MAX))
 740                         bch_verbose(c, "%s(): alloc info does not fit in ram, running in multiple passes with %zu nodes per pass",
 741                                     __func__, btree_nodes_fit_in_ram(c));
 742
 743                 if (!bpos_eq(start, POS_MIN) || !bpos_eq(end, SPOS_MAX)) {
 744                         struct printbuf buf = PRINTBUF;
 745
 746                         prt_str(&buf, "check_extents_to_backpointers(): ");
 747                         bch2_bpos_to_text(&buf, start);
 748                         prt_str(&buf, "-");
 749                         bch2_bpos_to_text(&buf, end);
 750
 751                         bch_verbose(c, "%s", buf.buf);
 752                         printbuf_exit(&buf);
 753                 }
 754
 755                 ret = bch2_check_extents_to_backpointers_pass(&trans, start, end);
 756                 if (ret || bpos_eq(end, SPOS_MAX))
 757                         break;
 758
 759                 start = bpos_successor(end);
 760         }
 761         bch2_trans_exit(&trans);
 762
 763         if (ret)
 764                 bch_err_fn(c, ret);
 765         return ret;
 766 }
 767
 768 static int check_one_backpointer(struct btree_trans *trans,
 769                                  struct bbpos start,
 770                                  struct bbpos end,
 771                                  struct bkey_s_c_backpointer bp,
 772                                  struct bpos *last_flushed_pos)
 773 {
 774         struct bch_fs *c = trans->c;
 775         struct btree_iter iter;
 776         struct bbpos pos = bp_to_bbpos(*bp.v);
 777         struct bkey_s_c k;
 778         struct printbuf buf = PRINTBUF;
 779         int ret;
 780
 781         if (bbpos_cmp(pos, start) < 0 ||
 782             bbpos_cmp(pos, end) > 0)
 783                 return 0;
 784
 785         k = bch2_backpointer_get_key(trans, &iter, bp.k->p, *bp.v, 0);
 786         ret = bkey_err(k);
 787         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 788                 return 0;
 789         if (ret)
 790                 return ret;
 791
 792         if (!k.k && !bpos_eq(*last_flushed_pos, bp.k->p)) {
 793                 *last_flushed_pos = bp.k->p;
 794                 ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 795                         -BCH_ERR_transaction_restart_write_buffer_flush;
 796                 goto out;
 797         }
 798
 799         if (fsck_err_on(!k.k, c,
 800                         "backpointer for missing extent\n  %s",
 801                         (bch2_bkey_val_to_text(&buf, c, bp.s_c), buf.buf))) {
 802                 ret = bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, bp.k->p);
 803                 goto out;
 804         }
 805 out:
 806 fsck_err:
 807         bch2_trans_iter_exit(trans, &iter);
 808         printbuf_exit(&buf);
 809         return ret;
 810 }
 811
 812 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
 813                                                    struct bbpos start,
 814                                                    struct bbpos end)
 815 {
 816         struct btree_iter iter;
 817         struct bkey_s_c k;
 818         struct bpos last_flushed_pos = SPOS_MAX;
 819
 820         return for_each_btree_key_commit(trans, iter, BTREE_ID_backpointers,
 821                                   POS_MIN, BTREE_ITER_PREFETCH, k,
 822                                   NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 823                 check_one_backpointer(trans, start, end,
 824                                       bkey_s_c_to_backpointer(k),
 825                                       &last_flushed_pos));
 826 }
 827
 828 int bch2_check_backpointers_to_extents(struct bch_fs *c)
 829 {
 830         struct btree_trans trans;
 831         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
 832         int ret;
 833
 834         bch2_trans_init(&trans, c, 0, 0);
 835         while (1) {
 836                 ret = bch2_get_btree_in_memory_pos(&trans,
 837                                                    (1U << BTREE_ID_extents)|
 838                                                    (1U << BTREE_ID_reflink),
 839                                                    ~0,
 840                                                    start, &end);
 841                 if (ret)
 842                         break;
 843
 844                 if (!bbpos_cmp(start, BBPOS_MIN) &&
 845                     bbpos_cmp(end, BBPOS_MAX))
 846                         bch_verbose(c, "%s(): extents do not fit in ram, running in multiple passes with %zu nodes per pass",
 847                                     __func__, btree_nodes_fit_in_ram(c));
 848
 849                 if (bbpos_cmp(start, BBPOS_MIN) ||
 850                     bbpos_cmp(end, BBPOS_MAX)) {
 851                         struct printbuf buf = PRINTBUF;
 852
 853                         prt_str(&buf, "check_backpointers_to_extents(): ");
 854                         bch2_bbpos_to_text(&buf, start);
 855                         prt_str(&buf, "-");
 856                         bch2_bbpos_to_text(&buf, end);
 857
 858                         bch_verbose(c, "%s", buf.buf);
 859                         printbuf_exit(&buf);
 860                 }
 861
 862                 ret = bch2_check_backpointers_to_extents_pass(&trans, start, end);
 863                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
 864                         break;
 865
 866                 start = bbpos_successor(end);
 867         }
 868         bch2_trans_exit(&trans);
 869
 870         if (ret)
 871                 bch_err_fn(c, ret);
 872         return ret;
 873 }