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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "bcachefs.h"
   3 #include "alloc_background.h"
   4 #include "backpointers.h"
   5 #include "btree_cache.h"
   6 #include "btree_update.h"
   7 #include "error.h"
   8
   9 #define MAX_EXTENT_COMPRESS_RATIO_SHIFT         10
  10
  11 /*
  12  * Convert from pos in backpointer btree to pos of corresponding bucket in alloc
  13  * btree:
  14  */
  15 static inline struct bpos bp_pos_to_bucket(const struct bch_fs *c,
  16                                            struct bpos bp_pos)
  17 {
  18         struct bch_dev *ca = bch_dev_bkey_exists(c, bp_pos.inode);
  19         u64 bucket_sector = bp_pos.offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT;
  20
  21         return POS(bp_pos.inode, sector_to_bucket(ca, bucket_sector));
  22 }
  23
  24 /*
  25  * Convert from pos in alloc btree + bucket offset to pos in backpointer btree:
  26  */
  27 static inline struct bpos bucket_pos_to_bp(const struct bch_fs *c,
  28                                            struct bpos bucket,
  29                                            u64 bucket_offset)
  30 {
  31         struct bch_dev *ca = bch_dev_bkey_exists(c, bucket.inode);
  32
  33         return POS(bucket.inode,
  34                    (bucket_to_sector(ca, bucket.offset) <<
  35                     MAX_EXTENT_COMPRESS_RATIO_SHIFT) + bucket_offset);
  36 }
  37
  38 void bch2_extent_ptr_to_bp(struct bch_fs *c,
  39                            enum btree_id btree_id, unsigned level,
  40                            struct bkey_s_c k, struct extent_ptr_decoded p,
  41                            struct bpos *bucket_pos, struct bch_backpointer *bp)
  42 {
  43         enum bch_data_type data_type = level ? BCH_DATA_btree : BCH_DATA_user;
  44         s64 sectors = level ? btree_sectors(c) : k.k->size;
  45         u32 bucket_offset;
  46
  47         *bucket_pos = PTR_BUCKET_POS_OFFSET(c, &p.ptr, &bucket_offset);
  48         *bp = (struct bch_backpointer) {
  49                 .btree_id       = btree_id,
  50                 .level          = level,
  51                 .data_type      = data_type,
  52                 .bucket_offset  = ((u64) bucket_offset << MAX_EXTENT_COMPRESS_RATIO_SHIFT) +
  53                         p.crc.offset,
  54                 .bucket_len     = ptr_disk_sectors(sectors, p),
  55                 .pos            = k.k->p,
  56         };
  57 }
  58
  59 static bool extent_matches_bp(struct bch_fs *c,
  60                               enum btree_id btree_id, unsigned level,
  61                               struct bkey_s_c k,
  62                               struct bpos bucket,
  63                               struct bch_backpointer bp)
  64 {
  65         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  66         const union bch_extent_entry *entry;
  67         struct extent_ptr_decoded p;
  68
  69         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  70                 struct bpos bucket2;
  71                 struct bch_backpointer bp2;
  72
  73                 if (p.ptr.cached)
  74                         continue;
  75
  76                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  77                                       &bucket2, &bp2);
  78                 if (!bpos_cmp(bucket, bucket2) &&
  79                     !memcmp(&bp, &bp2, sizeof(bp)))
  80                         return true;
  81         }
  82
  83         return false;
  84 }
  85
  86 int bch2_backpointer_invalid(const struct bch_fs *c, struct bkey_s_c k,
  87                              int rw, struct printbuf *err)
  88 {
  89         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  90         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  91
  92         if (bkey_val_bytes(bp.k) < sizeof(*bp.v)) {
  93                 prt_str(err, "incorrect value size");
  94                 return -EINVAL;
  95         }
  96
  97         if (bpos_cmp(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset))) {
  98                 prt_str(err, "backpointer at wrong pos");
  99                 return -EINVAL;
 100         }
 101
 102         return 0;
 103 }
 104
 105 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
 106 {
 107         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
 108                bch2_btree_ids[bp->btree_id],
 109                bp->level,
 110                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
 111                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
 112                bp->bucket_len);
 113         bch2_bpos_to_text(out, bp->pos);
 114 }
 115
 116 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 117 {
 118         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
 119 }
 120
 121 void bch2_backpointer_swab(struct bkey_s k)
 122 {
 123         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
 124
 125         bp.v->bucket_offset     = swab32(bp.v->bucket_offset);
 126         bp.v->bucket_len        = swab32(bp.v->bucket_len);
 127         bch2_bpos_swab(&bp.v->pos);
 128 }
 129
 130 #define BACKPOINTER_OFFSET_MAX  ((1ULL << 40) - 1)
 131
 132 static inline int backpointer_cmp(struct bch_backpointer l, struct bch_backpointer r)
 133 {
 134         return cmp_int(l.bucket_offset, r.bucket_offset);
 135 }
 136
 137 static int bch2_backpointer_del_by_offset(struct btree_trans *trans,
 138                                           struct bpos bucket,
 139                                           u64 bp_offset,
 140                                           struct bch_backpointer bp)
 141 {
 142         struct bch_fs *c = trans->c;
 143         struct btree_iter iter;
 144         struct bkey_s_c k;
 145         int ret;
 146
 147         if (bp_offset < BACKPOINTER_OFFSET_MAX) {
 148                 struct bch_backpointer *bps;
 149                 struct bkey_i_alloc_v4 *a;
 150                 unsigned i, nr;
 151
 152                 bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
 153                                      bucket,
 154                                      BTREE_ITER_INTENT|
 155                                      BTREE_ITER_SLOTS|
 156                                      BTREE_ITER_WITH_UPDATES);
 157                 k = bch2_btree_iter_peek_slot(&iter);
 158                 ret = bkey_err(k);
 159                 if (ret)
 160                         goto err;
 161
 162                 if (k.k->type != KEY_TYPE_alloc_v4) {
 163                         ret = -ENOENT;
 164                         goto err;
 165                 }
 166
 167                 a = bch2_alloc_to_v4_mut(trans, k);
 168                 ret = PTR_ERR_OR_ZERO(a);
 169                 if (ret)
 170                         goto err;
 171                 bps = alloc_v4_backpointers(&a->v);
 172                 nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 173
 174                 for (i = 0; i < nr; i++) {
 175                         if (bps[i].bucket_offset == bp_offset)
 176                                 goto found;
 177                         if (bps[i].bucket_offset > bp_offset)
 178                                 break;
 179                 }
 180
 181                 ret = -ENOENT;
 182                 goto err;
 183 found:
 184                 if (memcmp(&bps[i], &bp, sizeof(bp))) {
 185                         ret = -ENOENT;
 186                         goto err;
 187                 }
 188                 array_remove_item(bps, nr, i);
 189                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 190                 set_alloc_v4_u64s(a);
 191                 ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
 192         } else {
 193                 bp_offset -= BACKPOINTER_OFFSET_MAX;
 194
 195                 bch2_trans_iter_init(trans, &iter, BTREE_ID_backpointers,
 196                                      bucket_pos_to_bp(c, bucket, bp_offset),
 197                                      BTREE_ITER_INTENT|
 198                                      BTREE_ITER_SLOTS|
 199                                      BTREE_ITER_WITH_UPDATES);
 200                 k = bch2_btree_iter_peek_slot(&iter);
 201                 ret = bkey_err(k);
 202                 if (ret)
 203                         goto err;
 204
 205                 if (k.k->type != KEY_TYPE_backpointer ||
 206                     memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 207                         ret = -ENOENT;
 208                         goto err;
 209                 }
 210
 211                 ret = bch2_btree_delete_at(trans, &iter, 0);
 212         }
 213 err:
 214         bch2_trans_iter_exit(trans, &iter);
 215         return ret;
 216 }
 217
 218 int bch2_bucket_backpointer_del(struct btree_trans *trans,
 219                                 struct bkey_i_alloc_v4 *a,
 220                                 struct bch_backpointer bp,
 221                                 struct bkey_s_c orig_k)
 222 {
 223         struct bch_fs *c = trans->c;
 224         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 225         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 226         struct btree_iter bp_iter;
 227         struct bkey_s_c k;
 228         int ret;
 229
 230         for (i = 0; i < nr; i++) {
 231                 int cmp = backpointer_cmp(bps[i], bp) ?:
 232                         memcmp(&bps[i], &bp, sizeof(bp));
 233                 if (!cmp)
 234                         goto found;
 235                 if (cmp >= 0)
 236                         break;
 237         }
 238
 239         goto btree;
 240 found:
 241         array_remove_item(bps, nr, i);
 242         SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 243         set_alloc_v4_u64s(a);
 244         return 0;
 245 btree:
 246         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 247                              bucket_pos_to_bp(c, a->k.p, bp.bucket_offset),
 248                              BTREE_ITER_INTENT|
 249                              BTREE_ITER_SLOTS|
 250                              BTREE_ITER_WITH_UPDATES);
 251         k = bch2_btree_iter_peek_slot(&bp_iter);
 252         ret = bkey_err(k);
 253         if (ret)
 254                 goto err;
 255
 256         if (k.k->type != KEY_TYPE_backpointer ||
 257             memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 258                 struct printbuf buf = PRINTBUF;
 259
 260                 prt_printf(&buf, "backpointer not found when deleting");
 261                 prt_newline(&buf);
 262                 printbuf_indent_add(&buf, 2);
 263
 264                 prt_printf(&buf, "searching for ");
 265                 bch2_backpointer_to_text(&buf, &bp);
 266                 prt_newline(&buf);
 267
 268                 prt_printf(&buf, "got ");
 269                 bch2_bkey_val_to_text(&buf, c, k);
 270                 prt_newline(&buf);
 271
 272                 prt_str(&buf, "alloc ");
 273                 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
 274                 prt_newline(&buf);
 275
 276                 prt_printf(&buf, "for ");
 277                 bch2_bkey_val_to_text(&buf, c, orig_k);
 278
 279                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags)) {
 280                         bch_err(c, "%s", buf.buf);
 281                 } else {
 282                         ret = -EIO;
 283                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 284                 }
 285                 printbuf_exit(&buf);
 286                 goto err;
 287         }
 288
 289         ret = bch2_btree_delete_at(trans, &bp_iter, 0);
 290 err:
 291         bch2_trans_iter_exit(trans, &bp_iter);
 292         return ret;
 293 }
 294
 295 int bch2_bucket_backpointer_add(struct btree_trans *trans,
 296                                 struct bkey_i_alloc_v4 *a,
 297                                 struct bch_backpointer bp,
 298                                 struct bkey_s_c orig_k)
 299 {
 300         struct bch_fs *c = trans->c;
 301         struct bch_dev *ca;
 302         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 303         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 304         struct bkey_i_backpointer *bp_k;
 305         struct btree_iter bp_iter;
 306         struct bkey_s_c k;
 307         int ret;
 308
 309         /* Check for duplicates: */
 310         for (i = 0; i < nr; i++) {
 311                 int cmp = backpointer_cmp(bps[i], bp);
 312                 if (cmp >= 0)
 313                         break;
 314         }
 315
 316         if ((i &&
 317              (bps[i - 1].bucket_offset +
 318               bps[i - 1].bucket_len > bp.bucket_offset)) ||
 319             (i < nr &&
 320              (bp.bucket_offset + bp.bucket_len > bps[i].bucket_offset))) {
 321                 struct printbuf buf = PRINTBUF;
 322
 323                 prt_printf(&buf, "overlapping backpointer found when inserting ");
 324                 bch2_backpointer_to_text(&buf, &bp);
 325                 prt_newline(&buf);
 326                 printbuf_indent_add(&buf, 2);
 327
 328                 prt_printf(&buf, "into ");
 329                 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
 330                 prt_newline(&buf);
 331
 332                 prt_printf(&buf, "for ");
 333                 bch2_bkey_val_to_text(&buf, c, orig_k);
 334
 335                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 336                         bch_err(c, "%s", buf.buf);
 337                 else {
 338                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 339                         printbuf_exit(&buf);
 340                         return -EIO;
 341                 }
 342         }
 343
 344         if (nr < BCH_ALLOC_V4_NR_BACKPOINTERS_MAX) {
 345                 array_insert_item(bps, nr, i, bp);
 346                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 347                 set_alloc_v4_u64s(a);
 348                 return 0;
 349         }
 350
 351         /* Overflow: use backpointer btree */
 352         bp_k = bch2_trans_kmalloc(trans, sizeof(*bp_k));
 353         ret = PTR_ERR_OR_ZERO(bp_k);
 354         if (ret)
 355                 return ret;
 356
 357         ca = bch_dev_bkey_exists(c, a->k.p.inode);
 358
 359         bkey_backpointer_init(&bp_k->k_i);
 360         bp_k->k.p = bucket_pos_to_bp(c, a->k.p, bp.bucket_offset);
 361         bp_k->v = bp;
 362
 363         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers, bp_k->k.p,
 364                              BTREE_ITER_INTENT|
 365                              BTREE_ITER_SLOTS|
 366                              BTREE_ITER_WITH_UPDATES);
 367         k = bch2_btree_iter_peek_slot(&bp_iter);
 368         ret = bkey_err(k);
 369         if (ret)
 370                 goto err;
 371
 372         if (k.k->type) {
 373                 struct printbuf buf = PRINTBUF;
 374
 375                 prt_printf(&buf, "existing btree backpointer key found when inserting ");
 376                 bch2_backpointer_to_text(&buf, &bp);
 377                 prt_newline(&buf);
 378                 printbuf_indent_add(&buf, 2);
 379
 380                 prt_printf(&buf, "found ");
 381                 bch2_bkey_val_to_text(&buf, c, k);
 382                 prt_newline(&buf);
 383
 384                 prt_printf(&buf, "for ");
 385                 bch2_bkey_val_to_text(&buf, c, orig_k);
 386
 387                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 388                         bch_err(c, "%s", buf.buf);
 389                 else {
 390                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 391                         printbuf_exit(&buf);
 392                         ret = -EIO;
 393                         goto err;
 394                 }
 395         }
 396
 397         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 398 err:
 399         bch2_trans_iter_exit(trans, &bp_iter);
 400         return ret;
 401 }
 402
 403 /*
 404  * Find the next backpointer >= *bp_offset:
 405  */
 406 int bch2_get_next_backpointer(struct btree_trans *trans,
 407                               struct bpos bucket, int gen,
 408                               u64 *bp_offset,
 409                               struct bch_backpointer *dst)
 410 {
 411         struct bch_fs *c = trans->c;
 412         struct bpos bp_pos =
 413                 bucket_pos_to_bp(c, bucket,
 414                                 max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
 415         struct bpos bp_end_pos =
 416                 bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 417         struct btree_iter alloc_iter, bp_iter = { NULL };
 418         struct bkey_s_c k;
 419         struct bkey_s_c_alloc_v4 a;
 420         size_t i;
 421         int ret;
 422
 423         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 424                              bucket, BTREE_ITER_CACHED);
 425         k = bch2_btree_iter_peek_slot(&alloc_iter);
 426         ret = bkey_err(k);
 427         if (ret)
 428                 goto out;
 429
 430         if (k.k->type != KEY_TYPE_alloc_v4)
 431                 goto done;
 432
 433         a = bkey_s_c_to_alloc_v4(k);
 434         if (gen >= 0 && a.v->gen != gen)
 435                 goto done;
 436
 437         for (i = 0; i < BCH_ALLOC_V4_NR_BACKPOINTERS(a.v); i++) {
 438                 if (alloc_v4_backpointers_c(a.v)[i].bucket_offset < *bp_offset)
 439                         continue;
 440
 441                 *dst = alloc_v4_backpointers_c(a.v)[i];
 442                 *bp_offset = dst->bucket_offset;
 443                 goto out;
 444         }
 445
 446         for_each_btree_key(trans, bp_iter, BTREE_ID_backpointers,
 447                            bp_pos, 0, k, ret) {
 448                 if (bpos_cmp(k.k->p, bp_end_pos) >= 0)
 449                         break;
 450
 451                 if (k.k->type != KEY_TYPE_backpointer)
 452                         continue;
 453
 454                 *dst = *bkey_s_c_to_backpointer(k).v;
 455                 *bp_offset = dst->bucket_offset + BACKPOINTER_OFFSET_MAX;
 456                 goto out;
 457         }
 458 done:
 459         *bp_offset = U64_MAX;
 460 out:
 461         bch2_trans_iter_exit(trans, &bp_iter);
 462         bch2_trans_iter_exit(trans, &alloc_iter);
 463         return ret;
 464 }
 465
 466 static void backpointer_not_found(struct btree_trans *trans,
 467                                   struct bpos bucket,
 468                                   u64 bp_offset,
 469                                   struct bch_backpointer bp,
 470                                   struct bkey_s_c k,
 471                                   const char *thing_it_points_to)
 472 {
 473         struct bch_fs *c = trans->c;
 474         struct printbuf buf = PRINTBUF;
 475
 476         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 477                    thing_it_points_to);
 478         prt_printf(&buf, "bucket: ");
 479         bch2_bpos_to_text(&buf, bucket);
 480         prt_printf(&buf, "\n  ");
 481
 482         if (bp_offset >= BACKPOINTER_OFFSET_MAX) {
 483                 struct bpos bp_pos =
 484                         bucket_pos_to_bp(c, bucket,
 485                                         bp_offset - BACKPOINTER_OFFSET_MAX);
 486                 prt_printf(&buf, "backpointer pos: ");
 487                 bch2_bpos_to_text(&buf, bp_pos);
 488                 prt_printf(&buf, "\n  ");
 489         }
 490
 491         bch2_backpointer_to_text(&buf, &bp);
 492         prt_printf(&buf, "\n  ");
 493         bch2_bkey_val_to_text(&buf, c, k);
 494         if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 495                 bch_err(c, "%s", buf.buf);
 496         else
 497                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 498
 499         printbuf_exit(&buf);
 500 }
 501
 502 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 503                                          struct btree_iter *iter,
 504                                          struct bpos bucket,
 505                                          u64 bp_offset,
 506                                          struct bch_backpointer bp)
 507 {
 508         struct bch_fs *c = trans->c;
 509         struct bkey_s_c k;
 510
 511         bch2_trans_node_iter_init(trans, iter,
 512                                   bp.btree_id,
 513                                   bp.pos,
 514                                   0,
 515                                   min(bp.level, c->btree_roots[bp.btree_id].level),
 516                                   0);
 517         k = bch2_btree_iter_peek_slot(iter);
 518         if (bkey_err(k)) {
 519                 bch2_trans_iter_exit(trans, iter);
 520                 return k;
 521         }
 522
 523         if (bp.level == c->btree_roots[bp.btree_id].level + 1)
 524                 k = bkey_i_to_s_c(&c->btree_roots[bp.btree_id].key);
 525
 526         if (extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 527                 return k;
 528
 529         backpointer_not_found(trans, bucket, bp_offset, bp, k, "extent");
 530
 531         bch2_trans_iter_exit(trans, iter);
 532         return bkey_s_c_null;
 533 }
 534
 535 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 536                                         struct btree_iter *iter,
 537                                         struct bpos bucket,
 538                                         u64 bp_offset,
 539                                         struct bch_backpointer bp)
 540 {
 541         struct bch_fs *c = trans->c;
 542         struct btree *b;
 543         struct bkey_s_c k;
 544
 545         BUG_ON(!bp.level);
 546
 547         bch2_trans_node_iter_init(trans, iter,
 548                                   bp.btree_id,
 549                                   bp.pos,
 550                                   0,
 551                                   bp.level - 1,
 552                                   0);
 553         b = bch2_btree_iter_peek_node(iter);
 554         if (IS_ERR(b)) {
 555                 bch2_trans_iter_exit(trans, iter);
 556                 return b;
 557         }
 558
 559         if (extent_matches_bp(c, bp.btree_id, bp.level,
 560                               bkey_i_to_s_c(&b->key),
 561                               bucket, bp))
 562                 return b;
 563
 564         if (!btree_node_will_make_reachable(b))
 565                 backpointer_not_found(trans, bucket, bp_offset,
 566                                       bp, k, "btree node");
 567
 568         bch2_trans_iter_exit(trans, iter);
 569         return NULL;
 570 }
 571
 572 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter)
 573 {
 574         struct bch_fs *c = trans->c;
 575         struct btree_iter alloc_iter = { NULL };
 576         struct bch_dev *ca;
 577         struct bkey_s_c k, alloc_k;
 578         struct printbuf buf = PRINTBUF;
 579         int ret = 0;
 580
 581         k = bch2_btree_iter_peek(bp_iter);
 582         ret = bkey_err(k);
 583         if (ret)
 584                 return ret;
 585         if (!k.k)
 586                 return 0;
 587
 588         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 589                         "backpointer for mising device:\n%s",
 590                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 591                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 592                 goto out;
 593         }
 594
 595         ca = bch_dev_bkey_exists(c, k.k->p.inode);
 596
 597         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 598                              bp_pos_to_bucket(c, k.k->p), 0);
 599
 600         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 601         ret = bkey_err(alloc_k);
 602         if (ret)
 603                 goto out;
 604
 605         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 606                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 607                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 608                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 609                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 610                 goto out;
 611         }
 612 out:
 613 fsck_err:
 614         bch2_trans_iter_exit(trans, &alloc_iter);
 615         printbuf_exit(&buf);
 616         return ret;
 617 }
 618
 619 /* verify that every backpointer has a corresponding alloc key */
 620 int bch2_check_btree_backpointers(struct bch_fs *c)
 621 {
 622         struct btree_trans trans;
 623         struct btree_iter iter;
 624         int ret = 0;
 625
 626         bch2_trans_init(&trans, c, 0, 0);
 627         bch2_trans_iter_init(&trans, &iter, BTREE_ID_backpointers, POS_MIN, 0);
 628
 629         do {
 630                 ret = __bch2_trans_do(&trans, NULL, NULL,
 631                                       BTREE_INSERT_LAZY_RW|
 632                                       BTREE_INSERT_NOFAIL,
 633                                       bch2_check_btree_backpointer(&trans, &iter));
 634                 if (ret)
 635                         break;
 636         } while (bch2_btree_iter_advance(&iter));
 637
 638         bch2_trans_iter_exit(&trans, &iter);
 639         bch2_trans_exit(&trans);
 640         return ret;
 641 }
 642
 643 static int check_bp_exists(struct btree_trans *trans,
 644                            struct bpos bucket_pos,
 645                            struct bch_backpointer bp,
 646                            struct bkey_s_c orig_k)
 647 {
 648         struct bch_fs *c = trans->c;
 649         struct btree_iter alloc_iter, bp_iter = { NULL };
 650         struct printbuf buf = PRINTBUF;
 651         struct bkey_s_c alloc_k, bp_k;
 652         int ret;
 653
 654         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, bucket_pos, 0);
 655         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 656         ret = bkey_err(alloc_k);
 657         if (ret)
 658                 goto err;
 659
 660         if (alloc_k.k->type == KEY_TYPE_alloc_v4) {
 661                 struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(alloc_k);
 662                 const struct bch_backpointer *bps = alloc_v4_backpointers_c(a.v);
 663                 unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(a.v);
 664
 665                 for (i = 0; i < nr; i++) {
 666                         int cmp = backpointer_cmp(bps[i], bp) ?:
 667                                 memcmp(&bps[i], &bp, sizeof(bp));
 668                         if (!cmp)
 669                                 goto out;
 670                         if (cmp >= 0)
 671                                 break;
 672                 }
 673         } else {
 674                 goto missing;
 675         }
 676
 677         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 678                              bucket_pos_to_bp(c, bucket_pos, bp.bucket_offset),
 679                              0);
 680         bp_k = bch2_btree_iter_peek_slot(&bp_iter);
 681         ret = bkey_err(bp_k);
 682         if (ret)
 683                 goto err;
 684
 685         if (bp_k.k->type != KEY_TYPE_backpointer ||
 686             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp)))
 687                 goto missing;
 688 out:
 689 err:
 690 fsck_err:
 691         bch2_trans_iter_exit(trans, &bp_iter);
 692         bch2_trans_iter_exit(trans, &alloc_iter);
 693         printbuf_exit(&buf);
 694         return ret;
 695 missing:
 696         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 697                bch2_btree_ids[bp.btree_id], bp.level);
 698         bch2_bkey_val_to_text(&buf, c, orig_k);
 699         prt_printf(&buf, "\nin alloc key ");
 700         bch2_bkey_val_to_text(&buf, c, alloc_k);
 701
 702         if (c->sb.version < bcachefs_metadata_version_backpointers ||
 703             c->opts.reconstruct_alloc ||
 704             fsck_err(c, "%s", buf.buf)) {
 705                 struct bkey_i_alloc_v4 *a = bch2_alloc_to_v4_mut(trans, alloc_k);
 706
 707                 ret   = PTR_ERR_OR_ZERO(a) ?:
 708                         bch2_bucket_backpointer_add(trans, a, bp, orig_k) ?:
 709                         bch2_trans_update(trans, &alloc_iter, &a->k_i, 0);
 710         }
 711
 712         goto out;
 713 }
 714
 715 static int check_extent_to_backpointers(struct btree_trans *trans,
 716                                         struct btree_iter *iter)
 717 {
 718         struct bch_fs *c = trans->c;
 719         struct bkey_ptrs_c ptrs;
 720         const union bch_extent_entry *entry;
 721         struct extent_ptr_decoded p;
 722         struct bkey_s_c k;
 723         int ret;
 724
 725         k = bch2_btree_iter_peek_all_levels(iter);
 726         ret = bkey_err(k);
 727         if (ret)
 728                 return ret;
 729         if (!k.k)
 730                 return 0;
 731
 732         ptrs = bch2_bkey_ptrs_c(k);
 733         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 734                 struct bpos bucket_pos;
 735                 struct bch_backpointer bp;
 736
 737                 if (p.ptr.cached)
 738                         continue;
 739
 740                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 741                                       k, p, &bucket_pos, &bp);
 742
 743                 ret = check_bp_exists(trans, bucket_pos, bp, k);
 744                 if (ret)
 745                         return ret;
 746         }
 747
 748         return 0;
 749 }
 750
 751 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 752                                             enum btree_id btree_id)
 753 {
 754         struct bch_fs *c = trans->c;
 755         struct btree_iter iter;
 756         struct btree *b;
 757         struct bkey_s_c k;
 758         struct bkey_ptrs_c ptrs;
 759         struct extent_ptr_decoded p;
 760         const union bch_extent_entry *entry;
 761         int ret;
 762
 763         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 764                                   c->btree_roots[btree_id].level, 0);
 765         b = bch2_btree_iter_peek_node(&iter);
 766         ret = PTR_ERR_OR_ZERO(b);
 767         if (ret)
 768                 goto err;
 769
 770         BUG_ON(b != btree_node_root(c, b));
 771
 772         k = bkey_i_to_s_c(&b->key);
 773         ptrs = bch2_bkey_ptrs_c(k);
 774         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 775                 struct bpos bucket_pos;
 776                 struct bch_backpointer bp;
 777
 778                 if (p.ptr.cached)
 779                         continue;
 780
 781                 bch2_extent_ptr_to_bp(c, iter.btree_id, iter.path->level + 1,
 782                                       k, p, &bucket_pos, &bp);
 783
 784                 ret = check_bp_exists(trans, bucket_pos, bp, k);
 785                 if (ret)
 786                         goto err;
 787         }
 788 err:
 789         bch2_trans_iter_exit(trans, &iter);
 790         return ret;
 791 }
 792
 793 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 794 {
 795         struct btree_trans trans;
 796         struct btree_iter iter;
 797         enum btree_id btree_id;
 798         int ret = 0;
 799
 800         bch2_trans_init(&trans, c, 0, 0);
 801         for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
 802                 bch2_trans_node_iter_init(&trans, &iter, btree_id, POS_MIN, 0,
 803                                           0,
 804                                           BTREE_ITER_ALL_LEVELS|
 805                                           BTREE_ITER_PREFETCH);
 806
 807                 do {
 808                         ret = __bch2_trans_do(&trans, NULL, NULL,
 809                                               BTREE_INSERT_LAZY_RW|
 810                                               BTREE_INSERT_NOFAIL,
 811                                               check_extent_to_backpointers(&trans, &iter));
 812                         if (ret)
 813                                 break;
 814                 } while (!bch2_btree_iter_advance(&iter));
 815
 816                 bch2_trans_iter_exit(&trans, &iter);
 817
 818                 if (ret)
 819                         break;
 820
 821                 ret = __bch2_trans_do(&trans, NULL, NULL,
 822                                       BTREE_INSERT_LAZY_RW|
 823                                       BTREE_INSERT_NOFAIL,
 824                                       check_btree_root_to_backpointers(&trans, btree_id));
 825                 if (ret)
 826                         break;
 827         }
 828         bch2_trans_exit(&trans);
 829         return ret;
 830 }
 831
 832 static int check_one_backpointer(struct btree_trans *trans,
 833                                  struct bpos bucket,
 834                                  u64 *bp_offset)
 835 {
 836         struct btree_iter iter;
 837         struct bch_backpointer bp;
 838         struct bkey_s_c k;
 839         struct printbuf buf = PRINTBUF;
 840         int ret;
 841
 842         ret = bch2_get_next_backpointer(trans, bucket, -1,
 843                                         bp_offset, &bp);
 844         if (ret || *bp_offset == U64_MAX)
 845                 return ret;
 846
 847         k = bch2_backpointer_get_key(trans, &iter, bucket, *bp_offset, bp);
 848         ret = bkey_err(k);
 849         if (ret)
 850                 return ret;
 851
 852         if (fsck_err_on(!k.k, trans->c,
 853                         "%s backpointer points to missing extent\n%s",
 854                         *bp_offset < BACKPOINTER_OFFSET_MAX ? "alloc" : "btree",
 855                         (bch2_backpointer_to_text(&buf, &bp), buf.buf))) {
 856                 ret = bch2_backpointer_del_by_offset(trans, bucket, *bp_offset, bp);
 857                 if (ret == -ENOENT)
 858                         bch_err(trans->c, "backpointer at %llu not found", *bp_offset);
 859         }
 860
 861         bch2_trans_iter_exit(trans, &iter);
 862 fsck_err:
 863         printbuf_exit(&buf);
 864         return ret;
 865 }
 866
 867 int bch2_check_backpointers_to_extents(struct bch_fs *c)
 868 {
 869         struct btree_trans trans;
 870         struct btree_iter iter;
 871         struct bkey_s_c k;
 872         int ret = 0;
 873
 874         bch2_trans_init(&trans, c, 0, 0);
 875         for_each_btree_key(&trans, iter, BTREE_ID_alloc, POS_MIN,
 876                            BTREE_ITER_PREFETCH, k, ret) {
 877                 u64 bp_offset = 0;
 878
 879                 while (!(ret = __bch2_trans_do(&trans, NULL, NULL,
 880                                                BTREE_INSERT_LAZY_RW|
 881                                                BTREE_INSERT_NOFAIL,
 882                                 check_one_backpointer(&trans, iter.pos, &bp_offset))) &&
 883                        bp_offset < U64_MAX)
 884                         bp_offset++;
 885
 886                 if (ret)
 887                         break;
 888         }
 889         bch2_trans_iter_exit(&trans, &iter);
 890         bch2_trans_exit(&trans);
 891         return ret < 0 ? ret : 0;
 892 }