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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "bcachefs.h"
   3 #include "bbpos.h"
   4 #include "alloc_background.h"
   5 #include "backpointers.h"
   6 #include "btree_cache.h"
   7 #include "btree_update.h"
   8 #include "error.h"
   9
  10 #include <linux/mm.h>
  11
  12 #define MAX_EXTENT_COMPRESS_RATIO_SHIFT         10
  13
  14 /*
  15  * Convert from pos in backpointer btree to pos of corresponding bucket in alloc
  16  * btree:
  17  */
  18 static inline struct bpos bp_pos_to_bucket(const struct bch_fs *c,
  19                                            struct bpos bp_pos)
  20 {
  21         struct bch_dev *ca = bch_dev_bkey_exists(c, bp_pos.inode);
  22         u64 bucket_sector = bp_pos.offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT;
  23
  24         return POS(bp_pos.inode, sector_to_bucket(ca, bucket_sector));
  25 }
  26
  27 /*
  28  * Convert from pos in alloc btree + bucket offset to pos in backpointer btree:
  29  */
  30 static inline struct bpos bucket_pos_to_bp(const struct bch_fs *c,
  31                                            struct bpos bucket,
  32                                            u64 bucket_offset)
  33 {
  34         struct bch_dev *ca = bch_dev_bkey_exists(c, bucket.inode);
  35         struct bpos ret;
  36
  37         ret = POS(bucket.inode,
  38                   (bucket_to_sector(ca, bucket.offset) <<
  39                    MAX_EXTENT_COMPRESS_RATIO_SHIFT) + bucket_offset);
  40
  41         BUG_ON(bkey_cmp(bucket, bp_pos_to_bucket(c, ret)));
  42
  43         return ret;
  44 }
  45
  46 void bch2_extent_ptr_to_bp(struct bch_fs *c,
  47                            enum btree_id btree_id, unsigned level,
  48                            struct bkey_s_c k, struct extent_ptr_decoded p,
  49                            struct bpos *bucket_pos, struct bch_backpointer *bp)
  50 {
  51         enum bch_data_type data_type = level ? BCH_DATA_btree : BCH_DATA_user;
  52         s64 sectors = level ? btree_sectors(c) : k.k->size;
  53         u32 bucket_offset;
  54
  55         *bucket_pos = PTR_BUCKET_POS_OFFSET(c, &p.ptr, &bucket_offset);
  56         *bp = (struct bch_backpointer) {
  57                 .btree_id       = btree_id,
  58                 .level          = level,
  59                 .data_type      = data_type,
  60                 .bucket_offset  = ((u64) bucket_offset << MAX_EXTENT_COMPRESS_RATIO_SHIFT) +
  61                         p.crc.offset,
  62                 .bucket_len     = ptr_disk_sectors(sectors, p),
  63                 .pos            = k.k->p,
  64         };
  65 }
  66
  67 static bool extent_matches_bp(struct bch_fs *c,
  68                               enum btree_id btree_id, unsigned level,
  69                               struct bkey_s_c k,
  70                               struct bpos bucket,
  71                               struct bch_backpointer bp)
  72 {
  73         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  74         const union bch_extent_entry *entry;
  75         struct extent_ptr_decoded p;
  76
  77         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  78                 struct bpos bucket2;
  79                 struct bch_backpointer bp2;
  80
  81                 if (p.ptr.cached)
  82                         continue;
  83
  84                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  85                                       &bucket2, &bp2);
  86                 if (!bpos_cmp(bucket, bucket2) &&
  87                     !memcmp(&bp, &bp2, sizeof(bp)))
  88                         return true;
  89         }
  90
  91         return false;
  92 }
  93
  94 int bch2_backpointer_invalid(const struct bch_fs *c, struct bkey_s_c k,
  95                              int rw, struct printbuf *err)
  96 {
  97         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  98         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  99
 100         if (bkey_val_bytes(bp.k) < sizeof(*bp.v)) {
 101                 prt_str(err, "incorrect value size");
 102                 return -EINVAL;
 103         }
 104
 105         if (bpos_cmp(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset))) {
 106                 prt_str(err, "backpointer at wrong pos");
 107                 return -EINVAL;
 108         }
 109
 110         return 0;
 111 }
 112
 113 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
 114 {
 115         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
 116                bch2_btree_ids[bp->btree_id],
 117                bp->level,
 118                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
 119                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
 120                bp->bucket_len);
 121         bch2_bpos_to_text(out, bp->pos);
 122 }
 123
 124 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 125 {
 126         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
 127 }
 128
 129 void bch2_backpointer_swab(struct bkey_s k)
 130 {
 131         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
 132
 133         bp.v->bucket_offset     = swab32(bp.v->bucket_offset);
 134         bp.v->bucket_len        = swab32(bp.v->bucket_len);
 135         bch2_bpos_swab(&bp.v->pos);
 136 }
 137
 138 #define BACKPOINTER_OFFSET_MAX  ((1ULL << 40) - 1)
 139
 140 static inline int backpointer_cmp(struct bch_backpointer l, struct bch_backpointer r)
 141 {
 142         return cmp_int(l.bucket_offset, r.bucket_offset);
 143 }
 144
 145 static int bch2_backpointer_del_by_offset(struct btree_trans *trans,
 146                                           struct bpos bucket,
 147                                           u64 bp_offset,
 148                                           struct bch_backpointer bp)
 149 {
 150         struct bch_fs *c = trans->c;
 151         struct btree_iter iter;
 152         struct bkey_s_c k;
 153         int ret;
 154
 155         if (bp_offset < BACKPOINTER_OFFSET_MAX) {
 156                 struct bch_backpointer *bps;
 157                 struct bkey_i_alloc_v4 *a;
 158                 unsigned i, nr;
 159
 160                 bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
 161                                      bucket,
 162                                      BTREE_ITER_INTENT|
 163                                      BTREE_ITER_SLOTS|
 164                                      BTREE_ITER_WITH_UPDATES);
 165                 k = bch2_btree_iter_peek_slot(&iter);
 166                 ret = bkey_err(k);
 167                 if (ret)
 168                         goto err;
 169
 170                 if (k.k->type != KEY_TYPE_alloc_v4) {
 171                         ret = -ENOENT;
 172                         goto err;
 173                 }
 174
 175                 a = bch2_alloc_to_v4_mut(trans, k);
 176                 ret = PTR_ERR_OR_ZERO(a);
 177                 if (ret)
 178                         goto err;
 179                 bps = alloc_v4_backpointers(&a->v);
 180                 nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 181
 182                 for (i = 0; i < nr; i++) {
 183                         if (bps[i].bucket_offset == bp_offset)
 184                                 goto found;
 185                         if (bps[i].bucket_offset > bp_offset)
 186                                 break;
 187                 }
 188
 189                 ret = -ENOENT;
 190                 goto err;
 191 found:
 192                 if (memcmp(&bps[i], &bp, sizeof(bp))) {
 193                         ret = -ENOENT;
 194                         goto err;
 195                 }
 196                 array_remove_item(bps, nr, i);
 197                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 198                 set_alloc_v4_u64s(a);
 199                 ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
 200         } else {
 201                 bp_offset -= BACKPOINTER_OFFSET_MAX;
 202
 203                 bch2_trans_iter_init(trans, &iter, BTREE_ID_backpointers,
 204                                      bucket_pos_to_bp(c, bucket, bp_offset),
 205                                      BTREE_ITER_INTENT|
 206                                      BTREE_ITER_SLOTS|
 207                                      BTREE_ITER_WITH_UPDATES);
 208                 k = bch2_btree_iter_peek_slot(&iter);
 209                 ret = bkey_err(k);
 210                 if (ret)
 211                         goto err;
 212
 213                 if (k.k->type != KEY_TYPE_backpointer ||
 214                     memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 215                         ret = -ENOENT;
 216                         goto err;
 217                 }
 218
 219                 ret = bch2_btree_delete_at(trans, &iter, 0);
 220         }
 221 err:
 222         bch2_trans_iter_exit(trans, &iter);
 223         return ret;
 224 }
 225
 226 int bch2_bucket_backpointer_del(struct btree_trans *trans,
 227                                 struct bkey_i_alloc_v4 *a,
 228                                 struct bch_backpointer bp,
 229                                 struct bkey_s_c orig_k)
 230 {
 231         struct bch_fs *c = trans->c;
 232         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 233         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 234         struct btree_iter bp_iter;
 235         struct bkey_s_c k;
 236         int ret;
 237
 238         for (i = 0; i < nr; i++) {
 239                 int cmp = backpointer_cmp(bps[i], bp) ?:
 240                         memcmp(&bps[i], &bp, sizeof(bp));
 241                 if (!cmp)
 242                         goto found;
 243                 if (cmp >= 0)
 244                         break;
 245         }
 246
 247         goto btree;
 248 found:
 249         array_remove_item(bps, nr, i);
 250         SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 251         set_alloc_v4_u64s(a);
 252         return 0;
 253 btree:
 254         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 255                              bucket_pos_to_bp(c, a->k.p, bp.bucket_offset),
 256                              BTREE_ITER_INTENT|
 257                              BTREE_ITER_SLOTS|
 258                              BTREE_ITER_WITH_UPDATES);
 259         k = bch2_btree_iter_peek_slot(&bp_iter);
 260         ret = bkey_err(k);
 261         if (ret)
 262                 goto err;
 263
 264         if (k.k->type != KEY_TYPE_backpointer ||
 265             memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 266                 struct printbuf buf = PRINTBUF;
 267
 268                 prt_printf(&buf, "backpointer not found when deleting");
 269                 prt_newline(&buf);
 270                 printbuf_indent_add(&buf, 2);
 271
 272                 prt_printf(&buf, "searching for ");
 273                 bch2_backpointer_to_text(&buf, &bp);
 274                 prt_newline(&buf);
 275
 276                 prt_printf(&buf, "got ");
 277                 bch2_bkey_val_to_text(&buf, c, k);
 278                 prt_newline(&buf);
 279
 280                 prt_str(&buf, "alloc ");
 281                 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
 282                 prt_newline(&buf);
 283
 284                 prt_printf(&buf, "for ");
 285                 bch2_bkey_val_to_text(&buf, c, orig_k);
 286
 287                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags)) {
 288                         bch_err(c, "%s", buf.buf);
 289                 } else {
 290                         ret = -EIO;
 291                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 292                 }
 293                 printbuf_exit(&buf);
 294                 goto err;
 295         }
 296
 297         ret = bch2_btree_delete_at(trans, &bp_iter, 0);
 298 err:
 299         bch2_trans_iter_exit(trans, &bp_iter);
 300         return ret;
 301 }
 302
 303 int bch2_bucket_backpointer_add(struct btree_trans *trans,
 304                                 struct bkey_i_alloc_v4 *a,
 305                                 struct bch_backpointer bp,
 306                                 struct bkey_s_c orig_k)
 307 {
 308         struct bch_fs *c = trans->c;
 309         struct bch_dev *ca;
 310         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 311         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 312         struct bkey_i_backpointer *bp_k;
 313         struct btree_iter bp_iter;
 314         struct bkey_s_c k;
 315         int ret;
 316
 317         /* Check for duplicates: */
 318         for (i = 0; i < nr; i++) {
 319                 int cmp = backpointer_cmp(bps[i], bp);
 320                 if (cmp >= 0)
 321                         break;
 322         }
 323
 324         if ((i &&
 325              (bps[i - 1].bucket_offset +
 326               bps[i - 1].bucket_len > bp.bucket_offset)) ||
 327             (i < nr &&
 328              (bp.bucket_offset + bp.bucket_len > bps[i].bucket_offset))) {
 329                 struct printbuf buf = PRINTBUF;
 330
 331                 prt_printf(&buf, "overlapping backpointer found when inserting ");
 332                 bch2_backpointer_to_text(&buf, &bp);
 333                 prt_newline(&buf);
 334                 printbuf_indent_add(&buf, 2);
 335
 336                 prt_printf(&buf, "into ");
 337                 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
 338                 prt_newline(&buf);
 339
 340                 prt_printf(&buf, "for ");
 341                 bch2_bkey_val_to_text(&buf, c, orig_k);
 342
 343                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 344                         bch_err(c, "%s", buf.buf);
 345                 else {
 346                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 347                         printbuf_exit(&buf);
 348                         return -EIO;
 349                 }
 350         }
 351
 352         if (nr < BCH_ALLOC_V4_NR_BACKPOINTERS_MAX) {
 353                 array_insert_item(bps, nr, i, bp);
 354                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 355                 set_alloc_v4_u64s(a);
 356                 return 0;
 357         }
 358
 359         /* Overflow: use backpointer btree */
 360         bp_k = bch2_trans_kmalloc(trans, sizeof(*bp_k));
 361         ret = PTR_ERR_OR_ZERO(bp_k);
 362         if (ret)
 363                 return ret;
 364
 365         ca = bch_dev_bkey_exists(c, a->k.p.inode);
 366
 367         bkey_backpointer_init(&bp_k->k_i);
 368         bp_k->k.p = bucket_pos_to_bp(c, a->k.p, bp.bucket_offset);
 369         bp_k->v = bp;
 370
 371         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers, bp_k->k.p,
 372                              BTREE_ITER_INTENT|
 373                              BTREE_ITER_SLOTS|
 374                              BTREE_ITER_WITH_UPDATES);
 375         k = bch2_btree_iter_peek_slot(&bp_iter);
 376         ret = bkey_err(k);
 377         if (ret)
 378                 goto err;
 379
 380         if (k.k->type) {
 381                 struct printbuf buf = PRINTBUF;
 382
 383                 prt_printf(&buf, "existing btree backpointer key found when inserting ");
 384                 bch2_backpointer_to_text(&buf, &bp);
 385                 prt_newline(&buf);
 386                 printbuf_indent_add(&buf, 2);
 387
 388                 prt_printf(&buf, "found ");
 389                 bch2_bkey_val_to_text(&buf, c, k);
 390                 prt_newline(&buf);
 391
 392                 prt_printf(&buf, "for ");
 393                 bch2_bkey_val_to_text(&buf, c, orig_k);
 394
 395                 if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 396                         bch_err(c, "%s", buf.buf);
 397                 else {
 398                         bch2_trans_inconsistent(trans, "%s", buf.buf);
 399                         printbuf_exit(&buf);
 400                         ret = -EIO;
 401                         goto err;
 402                 }
 403         }
 404
 405         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 406 err:
 407         bch2_trans_iter_exit(trans, &bp_iter);
 408         return ret;
 409 }
 410
 411 /*
 412  * Find the next backpointer >= *bp_offset:
 413  */
 414 int bch2_get_next_backpointer(struct btree_trans *trans,
 415                               struct bpos bucket, int gen,
 416                               u64 *bp_offset,
 417                               struct bch_backpointer *dst,
 418                               unsigned iter_flags)
 419 {
 420         struct bch_fs *c = trans->c;
 421         struct bpos bp_pos, bp_end_pos;
 422         struct btree_iter alloc_iter, bp_iter = { NULL };
 423         struct bkey_s_c k;
 424         struct bkey_s_c_alloc_v4 a;
 425         size_t i;
 426         int ret;
 427
 428         if (*bp_offset == U64_MAX)
 429                 return 0;
 430
 431         bp_pos = bucket_pos_to_bp(c, bucket,
 432                                   max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
 433         bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 434
 435         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 436                              bucket, BTREE_ITER_CACHED);
 437         k = bch2_btree_iter_peek_slot(&alloc_iter);
 438         ret = bkey_err(k);
 439         if (ret)
 440                 goto out;
 441
 442         if (k.k->type != KEY_TYPE_alloc_v4)
 443                 goto done;
 444
 445         a = bkey_s_c_to_alloc_v4(k);
 446         if (gen >= 0 && a.v->gen != gen)
 447                 goto done;
 448
 449         for (i = 0; i < BCH_ALLOC_V4_NR_BACKPOINTERS(a.v); i++) {
 450                 if (alloc_v4_backpointers_c(a.v)[i].bucket_offset < *bp_offset)
 451                         continue;
 452
 453                 *dst = alloc_v4_backpointers_c(a.v)[i];
 454                 *bp_offset = dst->bucket_offset;
 455                 goto out;
 456         }
 457
 458         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 459                                      bp_pos, 0, k, ret) {
 460                 if (bpos_cmp(k.k->p, bp_end_pos) >= 0)
 461                         break;
 462
 463                 if (k.k->type != KEY_TYPE_backpointer)
 464                         continue;
 465
 466                 *dst = *bkey_s_c_to_backpointer(k).v;
 467                 *bp_offset = dst->bucket_offset + BACKPOINTER_OFFSET_MAX;
 468                 goto out;
 469         }
 470 done:
 471         *bp_offset = U64_MAX;
 472 out:
 473         bch2_trans_iter_exit(trans, &bp_iter);
 474         bch2_trans_iter_exit(trans, &alloc_iter);
 475         return ret;
 476 }
 477
 478 static void backpointer_not_found(struct btree_trans *trans,
 479                                   struct bpos bucket,
 480                                   u64 bp_offset,
 481                                   struct bch_backpointer bp,
 482                                   struct bkey_s_c k,
 483                                   const char *thing_it_points_to)
 484 {
 485         struct bch_fs *c = trans->c;
 486         struct printbuf buf = PRINTBUF;
 487
 488         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 489                    thing_it_points_to);
 490         prt_printf(&buf, "bucket: ");
 491         bch2_bpos_to_text(&buf, bucket);
 492         prt_printf(&buf, "\n  ");
 493
 494         if (bp_offset >= BACKPOINTER_OFFSET_MAX) {
 495                 struct bpos bp_pos =
 496                         bucket_pos_to_bp(c, bucket,
 497                                         bp_offset - BACKPOINTER_OFFSET_MAX);
 498                 prt_printf(&buf, "backpointer pos: ");
 499                 bch2_bpos_to_text(&buf, bp_pos);
 500                 prt_printf(&buf, "\n  ");
 501         }
 502
 503         bch2_backpointer_to_text(&buf, &bp);
 504         prt_printf(&buf, "\n  ");
 505         bch2_bkey_val_to_text(&buf, c, k);
 506         if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 507                 bch_err_ratelimited(c, "%s", buf.buf);
 508         else
 509                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 510
 511         printbuf_exit(&buf);
 512 }
 513
 514 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 515                                          struct btree_iter *iter,
 516                                          struct bpos bucket,
 517                                          u64 bp_offset,
 518                                          struct bch_backpointer bp)
 519 {
 520         struct bch_fs *c = trans->c;
 521         struct bkey_s_c k;
 522
 523         bch2_trans_node_iter_init(trans, iter,
 524                                   bp.btree_id,
 525                                   bp.pos,
 526                                   0,
 527                                   min(bp.level, c->btree_roots[bp.btree_id].level),
 528                                   0);
 529         k = bch2_btree_iter_peek_slot(iter);
 530         if (bkey_err(k)) {
 531                 bch2_trans_iter_exit(trans, iter);
 532                 return k;
 533         }
 534
 535         if (bp.level == c->btree_roots[bp.btree_id].level + 1)
 536                 k = bkey_i_to_s_c(&c->btree_roots[bp.btree_id].key);
 537
 538         if (extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 539                 return k;
 540
 541         bch2_trans_iter_exit(trans, iter);
 542
 543         if (bp.level) {
 544                 struct btree *b;
 545
 546                 /*
 547                  * If a backpointer for a btree node wasn't found, it may be
 548                  * because it was overwritten by a new btree node that hasn't
 549                  * been written out yet - backpointer_get_node() checks for
 550                  * this:
 551                  */
 552                 b = bch2_backpointer_get_node(trans, iter, bucket, bp_offset, bp);
 553                 if (!IS_ERR_OR_NULL(b))
 554                         return bkey_i_to_s_c(&b->key);
 555
 556                 bch2_trans_iter_exit(trans, iter);
 557
 558                 if (IS_ERR(b))
 559                         return bkey_s_c_err(PTR_ERR(b));
 560                 return bkey_s_c_null;
 561         }
 562
 563         backpointer_not_found(trans, bucket, bp_offset, bp, k, "extent");
 564         return bkey_s_c_null;
 565 }
 566
 567 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 568                                         struct btree_iter *iter,
 569                                         struct bpos bucket,
 570                                         u64 bp_offset,
 571                                         struct bch_backpointer bp)
 572 {
 573         struct bch_fs *c = trans->c;
 574         struct btree *b;
 575
 576         BUG_ON(!bp.level);
 577
 578         bch2_trans_node_iter_init(trans, iter,
 579                                   bp.btree_id,
 580                                   bp.pos,
 581                                   0,
 582                                   bp.level - 1,
 583                                   0);
 584         b = bch2_btree_iter_peek_node(iter);
 585         if (IS_ERR(b))
 586                 goto err;
 587
 588         if (extent_matches_bp(c, bp.btree_id, bp.level,
 589                               bkey_i_to_s_c(&b->key),
 590                               bucket, bp))
 591                 return b;
 592
 593         if (btree_node_will_make_reachable(b)) {
 594                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 595         } else {
 596                 backpointer_not_found(trans, bucket, bp_offset, bp,
 597                                       bkey_i_to_s_c(&b->key), "btree node");
 598                 b = NULL;
 599         }
 600 err:
 601         bch2_trans_iter_exit(trans, iter);
 602         return b;
 603 }
 604
 605 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 606                                         struct bkey_s_c k)
 607 {
 608         struct bch_fs *c = trans->c;
 609         struct btree_iter alloc_iter = { NULL };
 610         struct bch_dev *ca;
 611         struct bkey_s_c alloc_k;
 612         struct printbuf buf = PRINTBUF;
 613         int ret = 0;
 614
 615         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 616                         "backpointer for mising device:\n%s",
 617                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 618                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 619                 goto out;
 620         }
 621
 622         ca = bch_dev_bkey_exists(c, k.k->p.inode);
 623
 624         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 625                              bp_pos_to_bucket(c, k.k->p), 0);
 626
 627         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 628         ret = bkey_err(alloc_k);
 629         if (ret)
 630                 goto out;
 631
 632         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 633                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 634                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 635                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 636                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 637                 goto out;
 638         }
 639 out:
 640 fsck_err:
 641         bch2_trans_iter_exit(trans, &alloc_iter);
 642         printbuf_exit(&buf);
 643         return ret;
 644 }
 645
 646 /* verify that every backpointer has a corresponding alloc key */
 647 int bch2_check_btree_backpointers(struct bch_fs *c)
 648 {
 649         struct btree_iter iter;
 650         struct bkey_s_c k;
 651
 652         return bch2_trans_run(c,
 653                 for_each_btree_key_commit(&trans, iter,
 654                         BTREE_ID_backpointers, POS_MIN, 0, k,
 655                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 656                   bch2_check_btree_backpointer(&trans, &iter, k)));
 657 }
 658
 659 static int check_bp_exists(struct btree_trans *trans,
 660                            struct bpos bucket_pos,
 661                            struct bch_backpointer bp,
 662                            struct bkey_s_c orig_k,
 663                            struct bpos bucket_start,
 664                            struct bpos bucket_end)
 665 {
 666         struct bch_fs *c = trans->c;
 667         struct btree_iter alloc_iter, bp_iter = { NULL };
 668         struct printbuf buf = PRINTBUF;
 669         struct bkey_s_c alloc_k, bp_k;
 670         int ret;
 671
 672         if (bpos_cmp(bucket_pos, bucket_start) < 0 ||
 673             bpos_cmp(bucket_pos, bucket_end) > 0)
 674                 return 0;
 675
 676         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, bucket_pos, 0);
 677         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 678         ret = bkey_err(alloc_k);
 679         if (ret)
 680                 goto err;
 681
 682         if (alloc_k.k->type == KEY_TYPE_alloc_v4) {
 683                 struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(alloc_k);
 684                 const struct bch_backpointer *bps = alloc_v4_backpointers_c(a.v);
 685                 unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(a.v);
 686
 687                 for (i = 0; i < nr; i++) {
 688                         int cmp = backpointer_cmp(bps[i], bp) ?:
 689                                 memcmp(&bps[i], &bp, sizeof(bp));
 690                         if (!cmp)
 691                                 goto out;
 692                         if (cmp >= 0)
 693                                 break;
 694                 }
 695         } else {
 696                 goto missing;
 697         }
 698
 699         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 700                              bucket_pos_to_bp(c, bucket_pos, bp.bucket_offset),
 701                              0);
 702         bp_k = bch2_btree_iter_peek_slot(&bp_iter);
 703         ret = bkey_err(bp_k);
 704         if (ret)
 705                 goto err;
 706
 707         if (bp_k.k->type != KEY_TYPE_backpointer ||
 708             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp)))
 709                 goto missing;
 710 out:
 711 err:
 712 fsck_err:
 713         bch2_trans_iter_exit(trans, &bp_iter);
 714         bch2_trans_iter_exit(trans, &alloc_iter);
 715         printbuf_exit(&buf);
 716         return ret;
 717 missing:
 718         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 719                bch2_btree_ids[bp.btree_id], bp.level);
 720         bch2_bkey_val_to_text(&buf, c, orig_k);
 721         prt_printf(&buf, "\nin alloc key ");
 722         bch2_bkey_val_to_text(&buf, c, alloc_k);
 723
 724         if (c->sb.version < bcachefs_metadata_version_backpointers ||
 725             c->opts.reconstruct_alloc ||
 726             fsck_err(c, "%s", buf.buf)) {
 727                 struct bkey_i_alloc_v4 *a = bch2_alloc_to_v4_mut(trans, alloc_k);
 728
 729                 ret   = PTR_ERR_OR_ZERO(a) ?:
 730                         bch2_bucket_backpointer_add(trans, a, bp, orig_k) ?:
 731                         bch2_trans_update(trans, &alloc_iter, &a->k_i, 0);
 732         }
 733
 734         goto out;
 735 }
 736
 737 static int check_extent_to_backpointers(struct btree_trans *trans,
 738                                         struct btree_iter *iter,
 739                                         struct bpos bucket_start,
 740                                         struct bpos bucket_end)
 741 {
 742         struct bch_fs *c = trans->c;
 743         struct bkey_ptrs_c ptrs;
 744         const union bch_extent_entry *entry;
 745         struct extent_ptr_decoded p;
 746         struct bkey_s_c k;
 747         int ret;
 748
 749         k = bch2_btree_iter_peek_all_levels(iter);
 750         ret = bkey_err(k);
 751         if (ret)
 752                 return ret;
 753         if (!k.k)
 754                 return 0;
 755
 756         ptrs = bch2_bkey_ptrs_c(k);
 757         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 758                 struct bpos bucket_pos;
 759                 struct bch_backpointer bp;
 760
 761                 if (p.ptr.cached)
 762                         continue;
 763
 764                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 765                                       k, p, &bucket_pos, &bp);
 766
 767                 ret = check_bp_exists(trans, bucket_pos, bp, k, bucket_start, bucket_end);
 768                 if (ret)
 769                         return ret;
 770         }
 771
 772         return 0;
 773 }
 774
 775 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 776                                             enum btree_id btree_id,
 777                                             struct bpos bucket_start,
 778                                             struct bpos bucket_end)
 779 {
 780         struct bch_fs *c = trans->c;
 781         struct btree_iter iter;
 782         struct btree *b;
 783         struct bkey_s_c k;
 784         struct bkey_ptrs_c ptrs;
 785         struct extent_ptr_decoded p;
 786         const union bch_extent_entry *entry;
 787         int ret;
 788
 789         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 790                                   c->btree_roots[btree_id].level, 0);
 791         b = bch2_btree_iter_peek_node(&iter);
 792         ret = PTR_ERR_OR_ZERO(b);
 793         if (ret)
 794                 goto err;
 795
 796         BUG_ON(b != btree_node_root(c, b));
 797
 798         k = bkey_i_to_s_c(&b->key);
 799         ptrs = bch2_bkey_ptrs_c(k);
 800         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 801                 struct bpos bucket_pos;
 802                 struct bch_backpointer bp;
 803
 804                 if (p.ptr.cached)
 805                         continue;
 806
 807                 bch2_extent_ptr_to_bp(c, iter.btree_id, iter.path->level + 1,
 808                                       k, p, &bucket_pos, &bp);
 809
 810                 ret = check_bp_exists(trans, bucket_pos, bp, k, bucket_start, bucket_end);
 811                 if (ret)
 812                         goto err;
 813         }
 814 err:
 815         bch2_trans_iter_exit(trans, &iter);
 816         return ret;
 817 }
 818
 819 static inline struct bbpos bp_to_bbpos(struct bch_backpointer bp)
 820 {
 821         return (struct bbpos) {
 822                 .btree  = bp.btree_id,
 823                 .pos    = bp.pos,
 824         };
 825 }
 826
 827 static size_t btree_nodes_fit_in_ram(struct bch_fs *c)
 828 {
 829         struct sysinfo i;
 830         u64 mem_bytes;
 831
 832         si_meminfo(&i);
 833         mem_bytes = i.totalram * i.mem_unit;
 834         return (mem_bytes >> 1) / btree_bytes(c);
 835 }
 836
 837 int bch2_get_btree_in_memory_pos(struct btree_trans *trans,
 838                                  unsigned btree_leaf_mask,
 839                                  unsigned btree_interior_mask,
 840                                  struct bbpos start, struct bbpos *end)
 841 {
 842         struct btree_iter iter;
 843         struct bkey_s_c k;
 844         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 845         enum btree_id btree;
 846         int ret = 0;
 847
 848         for (btree = start.btree; btree < BTREE_ID_NR && !ret; btree++) {
 849                 unsigned depth = ((1U << btree) & btree_leaf_mask) ? 1 : 2;
 850
 851                 if (!((1U << btree) & btree_leaf_mask) &&
 852                     !((1U << btree) & btree_interior_mask))
 853                         continue;
 854
 855                 bch2_trans_node_iter_init(trans, &iter, btree,
 856                                           btree == start.btree ? start.pos : POS_MIN,
 857                                           0, depth, 0);
 858                 /*
 859                  * for_each_btree_key_contineu() doesn't check the return value
 860                  * from bch2_btree_iter_advance(), which is needed when
 861                  * iterating over interior nodes where we'll see keys at
 862                  * SPOS_MAX:
 863                  */
 864                 do {
 865                         k = __bch2_btree_iter_peek_and_restart(trans, &iter, 0);
 866                         ret = bkey_err(k);
 867                         if (!k.k || ret)
 868                                 break;
 869
 870                         --btree_nodes;
 871                         if (!btree_nodes) {
 872                                 *end = BBPOS(btree, k.k->p);
 873                                 bch2_trans_iter_exit(trans, &iter);
 874                                 return 0;
 875                         }
 876                 } while (bch2_btree_iter_advance(&iter));
 877                 bch2_trans_iter_exit(trans, &iter);
 878         }
 879
 880         *end = BBPOS_MAX;
 881         return ret;
 882 }
 883
 884 static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 885                                                    struct bpos bucket_start,
 886                                                    struct bpos bucket_end)
 887 {
 888         struct btree_iter iter;
 889         enum btree_id btree_id;
 890         int ret = 0;
 891
 892         for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
 893                 unsigned depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 894
 895                 bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 896                                           depth,
 897                                           BTREE_ITER_ALL_LEVELS|
 898                                           BTREE_ITER_PREFETCH);
 899
 900                 do {
 901                         ret = commit_do(trans, NULL, NULL,
 902                                         BTREE_INSERT_LAZY_RW|
 903                                         BTREE_INSERT_NOFAIL,
 904                                         check_extent_to_backpointers(trans, &iter,
 905                                                                 bucket_start, bucket_end));
 906                         if (ret)
 907                                 break;
 908                 } while (!bch2_btree_iter_advance(&iter));
 909
 910                 bch2_trans_iter_exit(trans, &iter);
 911
 912                 if (ret)
 913                         break;
 914
 915                 ret = commit_do(trans, NULL, NULL,
 916                                 BTREE_INSERT_LAZY_RW|
 917                                 BTREE_INSERT_NOFAIL,
 918                                 check_btree_root_to_backpointers(trans, btree_id,
 919                                                         bucket_start, bucket_end));
 920                 if (ret)
 921                         break;
 922         }
 923         return ret;
 924 }
 925
 926 int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 927                                  struct bpos start, struct bpos *end)
 928 {
 929         struct btree_iter alloc_iter;
 930         struct btree_iter bp_iter;
 931         struct bkey_s_c alloc_k, bp_k;
 932         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 933         bool alloc_end = false, bp_end = false;
 934         int ret = 0;
 935
 936         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 937                                   start, 0, 1, 0);
 938         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 939                                   bucket_pos_to_bp(trans->c, start, 0), 0, 1, 0);
 940         while (1) {
 941                 alloc_k = !alloc_end
 942                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 943                         : bkey_s_c_null;
 944                 bp_k = !bp_end
 945                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 946                         : bkey_s_c_null;
 947
 948                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 949                 if ((!alloc_k.k && !bp_k.k) || ret) {
 950                         *end = SPOS_MAX;
 951                         break;
 952                 }
 953
 954                 --btree_nodes;
 955                 if (!btree_nodes) {
 956                         *end = alloc_k.k->p;
 957                         break;
 958                 }
 959
 960                 if (bpos_cmp(alloc_iter.pos, SPOS_MAX) &&
 961                     bpos_cmp(bucket_pos_to_bp(trans->c, alloc_iter.pos, 0), bp_iter.pos) < 0) {
 962                         if (!bch2_btree_iter_advance(&alloc_iter))
 963                                 alloc_end = true;
 964                 } else {
 965                         if (!bch2_btree_iter_advance(&bp_iter))
 966                                 bp_end = true;
 967                 }
 968         }
 969         bch2_trans_iter_exit(trans, &bp_iter);
 970         bch2_trans_iter_exit(trans, &alloc_iter);
 971         return ret;
 972 }
 973
 974 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 975 {
 976         struct btree_trans trans;
 977         struct bpos start = POS_MIN, end;
 978         int ret;
 979
 980         bch2_trans_init(&trans, c, 0, 0);
 981         while (1) {
 982                 ret = bch2_get_alloc_in_memory_pos(&trans, start, &end);
 983                 if (ret)
 984                         break;
 985
 986                 if (!bpos_cmp(start, POS_MIN) && bpos_cmp(end, SPOS_MAX))
 987                         bch_verbose(c, "check_extents_to_backpointers(): alloc info does not fit in ram,"
 988                                     "running in multiple passes with %zu nodes per pass",
 989                                     btree_nodes_fit_in_ram(c));
 990
 991                 if (bpos_cmp(start, POS_MIN) || bpos_cmp(end, SPOS_MAX)) {
 992                         struct printbuf buf = PRINTBUF;
 993
 994                         prt_str(&buf, "check_extents_to_backpointers(): ");
 995                         bch2_bpos_to_text(&buf, start);
 996                         prt_str(&buf, "-");
 997                         bch2_bpos_to_text(&buf, end);
 998
 999                         bch_verbose(c, "%s", buf.buf);
1000                         printbuf_exit(&buf);
1001                 }
1002
1003                 ret = bch2_check_extents_to_backpointers_pass(&trans, start, end);
1004                 if (ret || !bpos_cmp(end, SPOS_MAX))
1005                         break;
1006
1007                 start = bpos_successor(end);
1008         }
1009         bch2_trans_exit(&trans);
1010
1011         return ret;
1012 }
1013
1014 static int check_one_backpointer(struct btree_trans *trans,
1015                                  struct bpos bucket,
1016                                  u64 *bp_offset,
1017                                  struct bbpos start,
1018                                  struct bbpos end)
1019 {
1020         struct btree_iter iter;
1021         struct bch_backpointer bp;
1022         struct bbpos pos;
1023         struct bkey_s_c k;
1024         struct printbuf buf = PRINTBUF;
1025         int ret;
1026
1027         ret = bch2_get_next_backpointer(trans, bucket, -1, bp_offset, &bp, 0);
1028         if (ret || *bp_offset == U64_MAX)
1029                 return ret;
1030
1031         pos = bp_to_bbpos(bp);
1032         if (bbpos_cmp(pos, start) < 0 ||
1033             bbpos_cmp(pos, end) > 0)
1034                 return 0;
1035
1036         k = bch2_backpointer_get_key(trans, &iter, bucket, *bp_offset, bp);
1037         ret = bkey_err(k);
1038         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
1039                 return 0;
1040         if (ret)
1041                 return ret;
1042
1043         if (fsck_err_on(!k.k, trans->c,
1044                         "%s backpointer points to missing extent\n%s",
1045                         *bp_offset < BACKPOINTER_OFFSET_MAX ? "alloc" : "btree",
1046                         (bch2_backpointer_to_text(&buf, &bp), buf.buf))) {
1047                 ret = bch2_backpointer_del_by_offset(trans, bucket, *bp_offset, bp);
1048                 if (ret == -ENOENT)
1049                         bch_err(trans->c, "backpointer at %llu not found", *bp_offset);
1050         }
1051
1052         bch2_trans_iter_exit(trans, &iter);
1053 fsck_err:
1054         printbuf_exit(&buf);
1055         return ret;
1056 }
1057
1058 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
1059                                                    struct bbpos start,
1060                                                    struct bbpos end)
1061 {
1062         struct btree_iter iter;
1063         struct bkey_s_c k;
1064         int ret = 0;
1065
1066         for_each_btree_key(trans, iter, BTREE_ID_alloc, POS_MIN,
1067                            BTREE_ITER_PREFETCH, k, ret) {
1068                 u64 bp_offset = 0;
1069
1070                 while (!(ret = commit_do(trans, NULL, NULL,
1071                                          BTREE_INSERT_LAZY_RW|
1072                                          BTREE_INSERT_NOFAIL,
1073                                 check_one_backpointer(trans, iter.pos, &bp_offset, start, end))) &&
1074                        bp_offset < U64_MAX)
1075                         bp_offset++;
1076
1077                 if (ret)
1078                         break;
1079         }
1080         bch2_trans_iter_exit(trans, &iter);
1081         return ret < 0 ? ret : 0;
1082 }
1083
1084 int bch2_check_backpointers_to_extents(struct bch_fs *c)
1085 {
1086         struct btree_trans trans;
1087         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
1088         int ret;
1089
1090         bch2_trans_init(&trans, c, 0, 0);
1091         while (1) {
1092                 ret = bch2_get_btree_in_memory_pos(&trans,
1093                                                    (1U << BTREE_ID_extents)|
1094                                                    (1U << BTREE_ID_reflink),
1095                                                    ~0,
1096                                                    start, &end);
1097                 if (ret)
1098                         break;
1099
1100                 if (!bbpos_cmp(start, BBPOS_MIN) &&
1101                     bbpos_cmp(end, BBPOS_MAX))
1102                         bch_verbose(c, "check_backpointers_to_extents(): extents do not fit in ram,"
1103                                     "running in multiple passes with %zu nodes per pass",
1104                                     btree_nodes_fit_in_ram(c));
1105
1106                 if (bbpos_cmp(start, BBPOS_MIN) ||
1107                     bbpos_cmp(end, BBPOS_MAX)) {
1108                         struct printbuf buf = PRINTBUF;
1109
1110                         prt_str(&buf, "check_backpointers_to_extents(): ");
1111                         bch2_bbpos_to_text(&buf, start);
1112                         prt_str(&buf, "-");
1113                         bch2_bbpos_to_text(&buf, end);
1114
1115                         bch_verbose(c, "%s", buf.buf);
1116                         printbuf_exit(&buf);
1117                 }
1118
1119                 ret = bch2_check_backpointers_to_extents_pass(&trans, start, end);
1120                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
1121                         break;
1122
1123                 start = bbpos_successor(end);
1124         }
1125         bch2_trans_exit(&trans);
1126
1127         return ret;
1128 }