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