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         struct bpos ret;
  33
  34         ret = POS(bucket.inode,
  35                   (bucket_to_sector(ca, bucket.offset) <<
  36                    MAX_EXTENT_COMPRESS_RATIO_SHIFT) + bucket_offset);
  37
  38         BUG_ON(bpos_cmp(bucket, bp_pos_to_bucket(c, ret)));
  39
  40         return ret;
  41 }
  42
  43 void bch2_extent_ptr_to_bp(struct bch_fs *c,
  44                            enum btree_id btree_id, unsigned level,
  45                            struct bkey_s_c k, struct extent_ptr_decoded p,
  46                            struct bpos *bucket_pos, struct bch_backpointer *bp)
  47 {
  48         enum bch_data_type data_type = level ? BCH_DATA_btree : BCH_DATA_user;
  49         s64 sectors = level ? btree_sectors(c) : k.k->size;
  50         u32 bucket_offset;
  51
  52         *bucket_pos = PTR_BUCKET_POS_OFFSET(c, &p.ptr, &bucket_offset);
  53         *bp = (struct bch_backpointer) {
  54                 .btree_id       = btree_id,
  55                 .level          = level,
  56                 .data_type      = data_type,
  57                 .bucket_offset  = ((u64) bucket_offset << MAX_EXTENT_COMPRESS_RATIO_SHIFT) +
  58                         p.crc.offset,
  59                 .bucket_len     = ptr_disk_sectors(sectors, p),
  60                 .pos            = k.k->p,
  61         };
  62 }
  63
  64 static bool extent_matches_bp(struct bch_fs *c,
  65                               enum btree_id btree_id, unsigned level,
  66                               struct bkey_s_c k,
  67                               struct bpos bucket,
  68                               struct bch_backpointer bp)
  69 {
  70         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  71         const union bch_extent_entry *entry;
  72         struct extent_ptr_decoded p;
  73
  74         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  75                 struct bpos bucket2;
  76                 struct bch_backpointer bp2;
  77
  78                 if (p.ptr.cached)
  79                         continue;
  80
  81                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  82                                       &bucket2, &bp2);
  83                 if (!bpos_cmp(bucket, bucket2) &&
  84                     !memcmp(&bp, &bp2, sizeof(bp)))
  85                         return true;
  86         }
  87
  88         return false;
  89 }
  90
  91 int bch2_backpointer_invalid(const struct bch_fs *c, struct bkey_s_c k,
  92                              int rw, struct printbuf *err)
  93 {
  94         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  95         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  96
  97         if (bkey_val_bytes(bp.k) < sizeof(*bp.v)) {
  98                 prt_str(err, "incorrect value size");
  99                 return -EINVAL;
 100         }
 101
 102         if (bpos_cmp(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset))) {
 103                 prt_str(err, "backpointer at wrong pos");
 104                 return -EINVAL;
 105         }
 106
 107         return 0;
 108 }
 109
 110 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
 111 {
 112         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
 113                bch2_btree_ids[bp->btree_id],
 114                bp->level,
 115                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
 116                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
 117                bp->bucket_len);
 118         bch2_bpos_to_text(out, bp->pos);
 119 }
 120
 121 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 122 {
 123         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
 124 }
 125
 126 void bch2_backpointer_swab(struct bkey_s k)
 127 {
 128         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
 129
 130         bp.v->bucket_offset     = swab32(bp.v->bucket_offset);
 131         bp.v->bucket_len        = swab32(bp.v->bucket_len);
 132         bch2_bpos_swab(&bp.v->pos);
 133 }
 134
 135 #define BACKPOINTER_OFFSET_MAX  ((1ULL << 40) - 1)
 136
 137 static inline int backpointer_cmp(struct bch_backpointer l, struct bch_backpointer r)
 138 {
 139         return cmp_int(l.bucket_offset, r.bucket_offset);
 140 }
 141
 142 static int bch2_backpointer_del_by_offset(struct btree_trans *trans,
 143                                           struct bpos bucket,
 144                                           u64 bp_offset,
 145                                           struct bch_backpointer bp)
 146 {
 147         struct bch_fs *c = trans->c;
 148         struct btree_iter iter;
 149         struct bkey_s_c k;
 150         int ret;
 151
 152         if (bp_offset < BACKPOINTER_OFFSET_MAX) {
 153                 struct bch_backpointer *bps;
 154                 struct bkey_i_alloc_v4 *a;
 155                 unsigned i, nr;
 156
 157                 bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
 158                                      bucket,
 159                                      BTREE_ITER_INTENT|
 160                                      BTREE_ITER_SLOTS|
 161                                      BTREE_ITER_WITH_UPDATES);
 162                 k = bch2_btree_iter_peek_slot(&iter);
 163                 ret = bkey_err(k);
 164                 if (ret)
 165                         goto err;
 166
 167                 if (k.k->type != KEY_TYPE_alloc_v4) {
 168                         ret = -ENOENT;
 169                         goto err;
 170                 }
 171
 172                 a = bch2_alloc_to_v4_mut(trans, k);
 173                 ret = PTR_ERR_OR_ZERO(a);
 174                 if (ret)
 175                         goto err;
 176                 bps = alloc_v4_backpointers(&a->v);
 177                 nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 178
 179                 for (i = 0; i < nr; i++) {
 180                         if (bps[i].bucket_offset == bp_offset)
 181                                 goto found;
 182                         if (bps[i].bucket_offset > bp_offset)
 183                                 break;
 184                 }
 185
 186                 ret = -ENOENT;
 187                 goto err;
 188 found:
 189                 if (memcmp(&bps[i], &bp, sizeof(bp))) {
 190                         ret = -ENOENT;
 191                         goto err;
 192                 }
 193                 array_remove_item(bps, nr, i);
 194                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 195                 set_alloc_v4_u64s(a);
 196                 ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
 197         } else {
 198                 bp_offset -= BACKPOINTER_OFFSET_MAX;
 199
 200                 bch2_trans_iter_init(trans, &iter, BTREE_ID_backpointers,
 201                                      bucket_pos_to_bp(c, bucket, bp_offset),
 202                                      BTREE_ITER_INTENT|
 203                                      BTREE_ITER_SLOTS|
 204                                      BTREE_ITER_WITH_UPDATES);
 205                 k = bch2_btree_iter_peek_slot(&iter);
 206                 ret = bkey_err(k);
 207                 if (ret)
 208                         goto err;
 209
 210                 if (k.k->type != KEY_TYPE_backpointer ||
 211                     memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 212                         ret = -ENOENT;
 213                         goto err;
 214                 }
 215
 216                 ret = bch2_btree_delete_at(trans, &iter, 0);
 217         }
 218 err:
 219         bch2_trans_iter_exit(trans, &iter);
 220         return ret;
 221 }
 222
 223 int bch2_bucket_backpointer_del(struct btree_trans *trans,
 224                                 struct bkey_i_alloc_v4 *a,
 225                                 struct bch_backpointer bp,
 226                                 struct bkey_s_c orig_k)
 227 {
 228         struct bch_fs *c = trans->c;
 229         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 230         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 231         struct btree_iter bp_iter;
 232         struct bkey_s_c k;
 233         int ret;
 234
 235         for (i = 0; i < nr; i++) {
 236                 int cmp = backpointer_cmp(bps[i], bp) ?:
 237                         memcmp(&bps[i], &bp, sizeof(bp));
 238                 if (!cmp)
 239                         goto found;
 240                 if (cmp >= 0)
 241                         break;
 242         }
 243
 244         goto btree;
 245 found:
 246         array_remove_item(bps, nr, i);
 247         SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 248         set_alloc_v4_u64s(a);
 249         return 0;
 250 btree:
 251         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 252                              bucket_pos_to_bp(c, a->k.p, bp.bucket_offset),
 253                              BTREE_ITER_INTENT|
 254                              BTREE_ITER_SLOTS|
 255                              BTREE_ITER_WITH_UPDATES);
 256         k = bch2_btree_iter_peek_slot(&bp_iter);
 257         ret = bkey_err(k);
 258         if (ret)
 259                 goto err;
 260
 261         if (k.k->type != KEY_TYPE_backpointer ||
 262             memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 263                 struct printbuf buf = PRINTBUF;
 264
 265                 prt_printf(&buf, "backpointer not found when deleting");
 266                 prt_newline(&buf);
 267                 printbuf_indent_add(&buf, 2);
 268
 269                 prt_printf(&buf, "searching for ");
 270                 bch2_backpointer_to_text(&buf, &bp);
 271                 prt_newline(&buf);
 272
 273                 prt_printf(&buf, "got ");
 274                 bch2_bkey_val_to_text(&buf, c, k);
 275                 prt_newline(&buf);
 276
 277                 prt_str(&buf, "alloc ");
 278                 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
 279                 prt_newline(&buf);
 280
 281                 prt_printf(&buf, "for ");
 282                 bch2_bkey_val_to_text(&buf, c, orig_k);
 283
 284                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags)) {
 285                         bch_err(c, "%s", buf.buf);
 286                 } else {
 287                         ret = -EIO;
 288                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 289                 }
 290                 printbuf_exit(&buf);
 291                 goto err;
 292         }
 293
 294         ret = bch2_btree_delete_at(trans, &bp_iter, 0);
 295 err:
 296         bch2_trans_iter_exit(trans, &bp_iter);
 297         return ret;
 298 }
 299
 300 int bch2_bucket_backpointer_add(struct btree_trans *trans,
 301                                 struct bkey_i_alloc_v4 *a,
 302                                 struct bch_backpointer bp,
 303                                 struct bkey_s_c orig_k)
 304 {
 305         struct bch_fs *c = trans->c;
 306         struct bch_dev *ca;
 307         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 308         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 309         struct bkey_i_backpointer *bp_k;
 310         struct btree_iter bp_iter;
 311         struct bkey_s_c k;
 312         int ret;
 313
 314         /* Check for duplicates: */
 315         for (i = 0; i < nr; i++) {
 316                 int cmp = backpointer_cmp(bps[i], bp);
 317                 if (cmp >= 0)
 318                         break;
 319         }
 320
 321         if ((i &&
 322              (bps[i - 1].bucket_offset +
 323               bps[i - 1].bucket_len > bp.bucket_offset)) ||
 324             (i < nr &&
 325              (bp.bucket_offset + bp.bucket_len > bps[i].bucket_offset))) {
 326                 struct printbuf buf = PRINTBUF;
 327
 328                 prt_printf(&buf, "overlapping backpointer found when inserting ");
 329                 bch2_backpointer_to_text(&buf, &bp);
 330                 prt_newline(&buf);
 331                 printbuf_indent_add(&buf, 2);
 332
 333                 prt_printf(&buf, "into ");
 334                 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
 335                 prt_newline(&buf);
 336
 337                 prt_printf(&buf, "for ");
 338                 bch2_bkey_val_to_text(&buf, c, orig_k);
 339
 340                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 341                         bch_err(c, "%s", buf.buf);
 342                 else {
 343                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 344                         printbuf_exit(&buf);
 345                         return -EIO;
 346                 }
 347         }
 348
 349         if (nr < BCH_ALLOC_V4_NR_BACKPOINTERS_MAX) {
 350                 array_insert_item(bps, nr, i, bp);
 351                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 352                 set_alloc_v4_u64s(a);
 353                 return 0;
 354         }
 355
 356         /* Overflow: use backpointer btree */
 357         bp_k = bch2_trans_kmalloc(trans, sizeof(*bp_k));
 358         ret = PTR_ERR_OR_ZERO(bp_k);
 359         if (ret)
 360                 return ret;
 361
 362         ca = bch_dev_bkey_exists(c, a->k.p.inode);
 363
 364         bkey_backpointer_init(&bp_k->k_i);
 365         bp_k->k.p = bucket_pos_to_bp(c, a->k.p, bp.bucket_offset);
 366         bp_k->v = bp;
 367
 368         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers, bp_k->k.p,
 369                              BTREE_ITER_INTENT|
 370                              BTREE_ITER_SLOTS|
 371                              BTREE_ITER_WITH_UPDATES);
 372         k = bch2_btree_iter_peek_slot(&bp_iter);
 373         ret = bkey_err(k);
 374         if (ret)
 375                 goto err;
 376
 377         if (k.k->type) {
 378                 struct printbuf buf = PRINTBUF;
 379
 380                 prt_printf(&buf, "existing btree backpointer key found when inserting ");
 381                 bch2_backpointer_to_text(&buf, &bp);
 382                 prt_newline(&buf);
 383                 printbuf_indent_add(&buf, 2);
 384
 385                 prt_printf(&buf, "found ");
 386                 bch2_bkey_val_to_text(&buf, c, k);
 387                 prt_newline(&buf);
 388
 389                 prt_printf(&buf, "for ");
 390                 bch2_bkey_val_to_text(&buf, c, orig_k);
 391
 392                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 393                         bch_err(c, "%s", buf.buf);
 394                 else {
 395                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 396                         printbuf_exit(&buf);
 397                         ret = -EIO;
 398                         goto err;
 399                 }
 400         }
 401
 402         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 403 err:
 404         bch2_trans_iter_exit(trans, &bp_iter);
 405         return ret;
 406 }
 407
 408 /*
 409  * Find the next backpointer >= *bp_offset:
 410  */
 411 int bch2_get_next_backpointer(struct btree_trans *trans,
 412                               struct bpos bucket, int gen,
 413                               u64 *bp_offset,
 414                               struct bch_backpointer *dst)
 415 {
 416         struct bch_fs *c = trans->c;
 417         struct bpos bp_pos, bp_end_pos;
 418         struct btree_iter alloc_iter, bp_iter = { NULL };
 419         struct bkey_s_c k;
 420         struct bkey_s_c_alloc_v4 a;
 421         size_t i;
 422         int ret;
 423
 424         if (*bp_offset == U64_MAX)
 425                 return 0;
 426
 427         bp_pos = bucket_pos_to_bp(c, bucket,
 428                                   max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
 429         bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 430
 431         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 432                              bucket, BTREE_ITER_CACHED);
 433         k = bch2_btree_iter_peek_slot(&alloc_iter);
 434         ret = bkey_err(k);
 435         if (ret)
 436                 goto out;
 437
 438         if (k.k->type != KEY_TYPE_alloc_v4)
 439                 goto done;
 440
 441         a = bkey_s_c_to_alloc_v4(k);
 442         if (gen >= 0 && a.v->gen != gen)
 443                 goto done;
 444
 445         for (i = 0; i < BCH_ALLOC_V4_NR_BACKPOINTERS(a.v); i++) {
 446                 if (alloc_v4_backpointers_c(a.v)[i].bucket_offset < *bp_offset)
 447                         continue;
 448
 449                 *dst = alloc_v4_backpointers_c(a.v)[i];
 450                 *bp_offset = dst->bucket_offset;
 451                 goto out;
 452         }
 453
 454         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 455                                      bp_pos, 0, k, ret) {
 456                 if (bpos_cmp(k.k->p, bp_end_pos) >= 0)
 457                         break;
 458
 459                 if (k.k->type != KEY_TYPE_backpointer)
 460                         continue;
 461
 462                 *dst = *bkey_s_c_to_backpointer(k).v;
 463                 *bp_offset = dst->bucket_offset + BACKPOINTER_OFFSET_MAX;
 464                 goto out;
 465         }
 466 done:
 467         *bp_offset = U64_MAX;
 468 out:
 469         bch2_trans_iter_exit(trans, &bp_iter);
 470         bch2_trans_iter_exit(trans, &alloc_iter);
 471         return ret;
 472 }
 473
 474 static void backpointer_not_found(struct btree_trans *trans,
 475                                   struct bpos bucket,
 476                                   u64 bp_offset,
 477                                   struct bch_backpointer bp,
 478                                   struct bkey_s_c k,
 479                                   const char *thing_it_points_to)
 480 {
 481         struct bch_fs *c = trans->c;
 482         struct printbuf buf = PRINTBUF;
 483
 484         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 485                    thing_it_points_to);
 486         prt_printf(&buf, "bucket: ");
 487         bch2_bpos_to_text(&buf, bucket);
 488         prt_printf(&buf, "\n  ");
 489
 490         if (bp_offset >= BACKPOINTER_OFFSET_MAX) {
 491                 struct bpos bp_pos =
 492                         bucket_pos_to_bp(c, bucket,
 493                                         bp_offset - BACKPOINTER_OFFSET_MAX);
 494                 prt_printf(&buf, "backpointer pos: ");
 495                 bch2_bpos_to_text(&buf, bp_pos);
 496                 prt_printf(&buf, "\n  ");
 497         }
 498
 499         bch2_backpointer_to_text(&buf, &bp);
 500         prt_printf(&buf, "\n  ");
 501         bch2_bkey_val_to_text(&buf, c, k);
 502         if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 503                 bch_err_ratelimited(c, "%s", buf.buf);
 504         else
 505                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 506
 507         printbuf_exit(&buf);
 508 }
 509
 510 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 511                                          struct btree_iter *iter,
 512                                          struct bpos bucket,
 513                                          u64 bp_offset,
 514                                          struct bch_backpointer bp)
 515 {
 516         struct bch_fs *c = trans->c;
 517         struct bkey_s_c k;
 518
 519         bch2_trans_node_iter_init(trans, iter,
 520                                   bp.btree_id,
 521                                   bp.pos,
 522                                   0,
 523                                   min(bp.level, c->btree_roots[bp.btree_id].level),
 524                                   0);
 525         k = bch2_btree_iter_peek_slot(iter);
 526         if (bkey_err(k)) {
 527                 bch2_trans_iter_exit(trans, iter);
 528                 return k;
 529         }
 530
 531         if (bp.level == c->btree_roots[bp.btree_id].level + 1)
 532                 k = bkey_i_to_s_c(&c->btree_roots[bp.btree_id].key);
 533
 534         if (extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 535                 return k;
 536
 537         bch2_trans_iter_exit(trans, iter);
 538
 539         if (bp.level) {
 540                 struct btree *b;
 541
 542                 /*
 543                  * If a backpointer for a btree node wasn't found, it may be
 544                  * because it was overwritten by a new btree node that hasn't
 545                  * been written out yet - backpointer_get_node() checks for
 546                  * this:
 547                  */
 548                 b = bch2_backpointer_get_node(trans, iter, bucket, bp_offset, bp);
 549                 if (!IS_ERR_OR_NULL(b))
 550                         return bkey_i_to_s_c(&b->key);
 551
 552                 bch2_trans_iter_exit(trans, iter);
 553
 554                 if (IS_ERR(b))
 555                         return bkey_s_c_err(PTR_ERR(b));
 556                 return bkey_s_c_null;
 557         }
 558
 559         backpointer_not_found(trans, bucket, bp_offset, bp, k, "extent");
 560         return bkey_s_c_null;
 561 }
 562
 563 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 564                                         struct btree_iter *iter,
 565                                         struct bpos bucket,
 566                                         u64 bp_offset,
 567                                         struct bch_backpointer bp)
 568 {
 569         struct bch_fs *c = trans->c;
 570         struct btree *b;
 571
 572         BUG_ON(!bp.level);
 573
 574         bch2_trans_node_iter_init(trans, iter,
 575                                   bp.btree_id,
 576                                   bp.pos,
 577                                   0,
 578                                   bp.level - 1,
 579                                   0);
 580         b = bch2_btree_iter_peek_node(iter);
 581         if (IS_ERR(b))
 582                 goto err;
 583
 584         if (extent_matches_bp(c, bp.btree_id, bp.level,
 585                               bkey_i_to_s_c(&b->key),
 586                               bucket, bp))
 587                 return b;
 588
 589         if (btree_node_will_make_reachable(b)) {
 590                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 591         } else {
 592                 backpointer_not_found(trans, bucket, bp_offset, bp,
 593                                       bkey_i_to_s_c(&b->key), "btree node");
 594                 b = NULL;
 595         }
 596 err:
 597         bch2_trans_iter_exit(trans, iter);
 598         return b;
 599 }
 600
 601 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 602                                         struct bkey_s_c k)
 603 {
 604         struct bch_fs *c = trans->c;
 605         struct btree_iter alloc_iter = { NULL };
 606         struct bch_dev *ca;
 607         struct bkey_s_c alloc_k;
 608         struct printbuf buf = PRINTBUF;
 609         int ret = 0;
 610
 611         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 612                         "backpointer for mising device:\n%s",
 613                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 614                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 615                 goto out;
 616         }
 617
 618         ca = bch_dev_bkey_exists(c, k.k->p.inode);
 619
 620         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 621                              bp_pos_to_bucket(c, k.k->p), 0);
 622
 623         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 624         ret = bkey_err(alloc_k);
 625         if (ret)
 626                 goto out;
 627
 628         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 629                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 630                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 631                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 632                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 633                 goto out;
 634         }
 635 out:
 636 fsck_err:
 637         bch2_trans_iter_exit(trans, &alloc_iter);
 638         printbuf_exit(&buf);
 639         return ret;
 640 }
 641
 642 /* verify that every backpointer has a corresponding alloc key */
 643 int bch2_check_btree_backpointers(struct bch_fs *c)
 644 {
 645         struct btree_iter iter;
 646         struct bkey_s_c k;
 647
 648         return bch2_trans_run(c,
 649                 for_each_btree_key_commit(&trans, iter,
 650                         BTREE_ID_backpointers, POS_MIN, 0, k,
 651                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 652                   bch2_check_btree_backpointer(&trans, &iter, k)));
 653 }
 654
 655 static int check_bp_exists(struct btree_trans *trans,
 656                            struct bpos bucket_pos,
 657                            struct bch_backpointer bp,
 658                            struct bkey_s_c orig_k)
 659 {
 660         struct bch_fs *c = trans->c;
 661         struct btree_iter alloc_iter, bp_iter = { NULL };
 662         struct printbuf buf = PRINTBUF;
 663         struct bkey_s_c alloc_k, bp_k;
 664         int ret;
 665
 666         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, bucket_pos, 0);
 667         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 668         ret = bkey_err(alloc_k);
 669         if (ret)
 670                 goto err;
 671
 672         if (alloc_k.k->type == KEY_TYPE_alloc_v4) {
 673                 struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(alloc_k);
 674                 const struct bch_backpointer *bps = alloc_v4_backpointers_c(a.v);
 675                 unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(a.v);
 676
 677                 for (i = 0; i < nr; i++) {
 678                         int cmp = backpointer_cmp(bps[i], bp) ?:
 679                                 memcmp(&bps[i], &bp, sizeof(bp));
 680                         if (!cmp)
 681                                 goto out;
 682                         if (cmp >= 0)
 683                                 break;
 684                 }
 685         } else {
 686                 goto missing;
 687         }
 688
 689         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 690                              bucket_pos_to_bp(c, bucket_pos, bp.bucket_offset),
 691                              0);
 692         bp_k = bch2_btree_iter_peek_slot(&bp_iter);
 693         ret = bkey_err(bp_k);
 694         if (ret)
 695                 goto err;
 696
 697         if (bp_k.k->type != KEY_TYPE_backpointer ||
 698             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp)))
 699                 goto missing;
 700 out:
 701 err:
 702 fsck_err:
 703         bch2_trans_iter_exit(trans, &bp_iter);
 704         bch2_trans_iter_exit(trans, &alloc_iter);
 705         printbuf_exit(&buf);
 706         return ret;
 707 missing:
 708         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 709                bch2_btree_ids[bp.btree_id], bp.level);
 710         bch2_bkey_val_to_text(&buf, c, orig_k);
 711         prt_printf(&buf, "\nin alloc key ");
 712         bch2_bkey_val_to_text(&buf, c, alloc_k);
 713
 714         if (c->sb.version < bcachefs_metadata_version_backpointers ||
 715             c->opts.reconstruct_alloc ||
 716             fsck_err(c, "%s", buf.buf)) {
 717                 struct bkey_i_alloc_v4 *a = bch2_alloc_to_v4_mut(trans, alloc_k);
 718
 719                 ret   = PTR_ERR_OR_ZERO(a) ?:
 720                         bch2_bucket_backpointer_add(trans, a, bp, orig_k) ?:
 721                         bch2_trans_update(trans, &alloc_iter, &a->k_i, 0);
 722         }
 723
 724         goto out;
 725 }
 726
 727 static int check_extent_to_backpointers(struct btree_trans *trans,
 728                                         struct btree_iter *iter)
 729 {
 730         struct bch_fs *c = trans->c;
 731         struct bkey_ptrs_c ptrs;
 732         const union bch_extent_entry *entry;
 733         struct extent_ptr_decoded p;
 734         struct bkey_s_c k;
 735         int ret;
 736
 737         k = bch2_btree_iter_peek_all_levels(iter);
 738         ret = bkey_err(k);
 739         if (ret)
 740                 return ret;
 741         if (!k.k)
 742                 return 0;
 743
 744         ptrs = bch2_bkey_ptrs_c(k);
 745         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 746                 struct bpos bucket_pos;
 747                 struct bch_backpointer bp;
 748
 749                 if (p.ptr.cached)
 750                         continue;
 751
 752                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 753                                       k, p, &bucket_pos, &bp);
 754
 755                 ret = check_bp_exists(trans, bucket_pos, bp, k);
 756                 if (ret)
 757                         return ret;
 758         }
 759
 760         return 0;
 761 }
 762
 763 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 764                                             enum btree_id btree_id)
 765 {
 766         struct bch_fs *c = trans->c;
 767         struct btree_iter iter;
 768         struct btree *b;
 769         struct bkey_s_c k;
 770         struct bkey_ptrs_c ptrs;
 771         struct extent_ptr_decoded p;
 772         const union bch_extent_entry *entry;
 773         int ret;
 774
 775         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 776                                   c->btree_roots[btree_id].level, 0);
 777         b = bch2_btree_iter_peek_node(&iter);
 778         ret = PTR_ERR_OR_ZERO(b);
 779         if (ret)
 780                 goto err;
 781
 782         BUG_ON(b != btree_node_root(c, b));
 783
 784         k = bkey_i_to_s_c(&b->key);
 785         ptrs = bch2_bkey_ptrs_c(k);
 786         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 787                 struct bpos bucket_pos;
 788                 struct bch_backpointer bp;
 789
 790                 if (p.ptr.cached)
 791                         continue;
 792
 793                 bch2_extent_ptr_to_bp(c, iter.btree_id, iter.path->level + 1,
 794                                       k, p, &bucket_pos, &bp);
 795
 796                 ret = check_bp_exists(trans, bucket_pos, bp, k);
 797                 if (ret)
 798                         goto err;
 799         }
 800 err:
 801         bch2_trans_iter_exit(trans, &iter);
 802         return ret;
 803 }
 804
 805 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 806 {
 807         struct btree_trans trans;
 808         struct btree_iter iter;
 809         enum btree_id btree_id;
 810         int ret = 0;
 811
 812         bch2_trans_init(&trans, c, 0, 0);
 813         for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
 814                 unsigned depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 815
 816                 bch2_trans_node_iter_init(&trans, &iter, btree_id, POS_MIN, 0,
 817                                           depth,
 818                                           BTREE_ITER_ALL_LEVELS|
 819                                           BTREE_ITER_PREFETCH);
 820
 821                 do {
 822                         ret = commit_do(&trans, NULL, NULL,
 823                                               BTREE_INSERT_LAZY_RW|
 824                                               BTREE_INSERT_NOFAIL,
 825                                               check_extent_to_backpointers(&trans, &iter));
 826                         if (ret)
 827                                 break;
 828                 } while (!bch2_btree_iter_advance(&iter));
 829
 830                 bch2_trans_iter_exit(&trans, &iter);
 831
 832                 if (ret)
 833                         break;
 834
 835                 ret = commit_do(&trans, NULL, NULL,
 836                                       BTREE_INSERT_LAZY_RW|
 837                                       BTREE_INSERT_NOFAIL,
 838                                       check_btree_root_to_backpointers(&trans, btree_id));
 839                 if (ret)
 840                         break;
 841         }
 842         bch2_trans_exit(&trans);
 843         return ret;
 844 }
 845
 846 static int check_one_backpointer(struct btree_trans *trans,
 847                                  struct bpos bucket,
 848                                  u64 *bp_offset)
 849 {
 850         struct btree_iter iter;
 851         struct bch_backpointer bp;
 852         struct bkey_s_c k;
 853         struct printbuf buf = PRINTBUF;
 854         int ret;
 855
 856         ret = bch2_get_next_backpointer(trans, bucket, -1,
 857                                         bp_offset, &bp);
 858         if (ret || *bp_offset == U64_MAX)
 859                 return ret;
 860
 861         k = bch2_backpointer_get_key(trans, &iter, bucket, *bp_offset, bp);
 862         ret = bkey_err(k);
 863         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 864                 return 0;
 865         if (ret)
 866                 return ret;
 867
 868         if (fsck_err_on(!k.k, trans->c,
 869                         "%s backpointer points to missing extent\n%s",
 870                         *bp_offset < BACKPOINTER_OFFSET_MAX ? "alloc" : "btree",
 871                         (bch2_backpointer_to_text(&buf, &bp), buf.buf))) {
 872                 ret = bch2_backpointer_del_by_offset(trans, bucket, *bp_offset, bp);
 873                 if (ret == -ENOENT)
 874                         bch_err(trans->c, "backpointer at %llu not found", *bp_offset);
 875         }
 876
 877         bch2_trans_iter_exit(trans, &iter);
 878 fsck_err:
 879         printbuf_exit(&buf);
 880         return ret;
 881 }
 882
 883 int bch2_check_backpointers_to_extents(struct bch_fs *c)
 884 {
 885         struct btree_trans trans;
 886         struct btree_iter iter;
 887         struct bkey_s_c k;
 888         int ret = 0;
 889
 890         bch2_trans_init(&trans, c, 0, 0);
 891         for_each_btree_key(&trans, iter, BTREE_ID_alloc, POS_MIN,
 892                            BTREE_ITER_PREFETCH, k, ret) {
 893                 u64 bp_offset = 0;
 894
 895                 while (!(ret = commit_do(&trans, NULL, NULL,
 896                                                BTREE_INSERT_LAZY_RW|
 897                                                BTREE_INSERT_NOFAIL,
 898                                 check_one_backpointer(&trans, iter.pos, &bp_offset))) &&
 899                        bp_offset < U64_MAX)
 900                         bp_offset++;
 901
 902                 if (ret)
 903                         break;
 904         }
 905         bch2_trans_iter_exit(&trans, &iter);
 906         bch2_trans_exit(&trans);
 907         return ret < 0 ? ret : 0;
 908 }