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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "bcachefs.h"
   3 #include "bbpos.h"
   4 #include "alloc_background.h"
   5 #include "backpointers.h"
   6 #include "btree_cache.h"
   7 #include "btree_update.h"
   8 #include "btree_write_buffer.h"
   9 #include "error.h"
  10
  11 #include <linux/mm.h>
  12
  13 static bool extent_matches_bp(struct bch_fs *c,
  14                               enum btree_id btree_id, unsigned level,
  15                               struct bkey_s_c k,
  16                               struct bpos bucket,
  17                               struct bch_backpointer bp)
  18 {
  19         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  20         const union bch_extent_entry *entry;
  21         struct extent_ptr_decoded p;
  22
  23         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
  24                 struct bpos bucket2;
  25                 struct bch_backpointer bp2;
  26
  27                 if (p.ptr.cached)
  28                         continue;
  29
  30                 bch2_extent_ptr_to_bp(c, btree_id, level, k, p,
  31                                       &bucket2, &bp2);
  32                 if (bpos_eq(bucket, bucket2) &&
  33                     !memcmp(&bp, &bp2, sizeof(bp)))
  34                         return true;
  35         }
  36
  37         return false;
  38 }
  39
  40 int bch2_backpointer_invalid(const struct bch_fs *c, struct bkey_s_c k,
  41                              unsigned flags, struct printbuf *err)
  42 {
  43         struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
  44         struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
  45
  46         if (bkey_val_bytes(bp.k) < sizeof(*bp.v)) {
  47                 prt_str(err, "incorrect value size");
  48                 return -BCH_ERR_invalid_bkey;
  49         }
  50
  51         if (!bpos_eq(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset))) {
  52                 prt_str(err, "backpointer at wrong pos");
  53                 return -BCH_ERR_invalid_bkey;
  54         }
  55
  56         return 0;
  57 }
  58
  59 void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer *bp)
  60 {
  61         prt_printf(out, "btree=%s l=%u offset=%llu:%u len=%u pos=",
  62                bch2_btree_ids[bp->btree_id],
  63                bp->level,
  64                (u64) (bp->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  65                (u32) bp->bucket_offset & ~(~0U << MAX_EXTENT_COMPRESS_RATIO_SHIFT),
  66                bp->bucket_len);
  67         bch2_bpos_to_text(out, bp->pos);
  68 }
  69
  70 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
  71 {
  72         bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
  73 }
  74
  75 void bch2_backpointer_swab(struct bkey_s k)
  76 {
  77         struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
  78
  79         bp.v->bucket_offset     = swab32(bp.v->bucket_offset);
  80         bp.v->bucket_len        = swab32(bp.v->bucket_len);
  81         bch2_bpos_swab(&bp.v->pos);
  82 }
  83
  84 #define BACKPOINTER_OFFSET_MAX  ((1ULL << 40) - 1)
  85
  86 static inline int backpointer_cmp(struct bch_backpointer l, struct bch_backpointer r)
  87 {
  88         return cmp_int(l.bucket_offset, r.bucket_offset);
  89 }
  90
  91 static int bch2_backpointer_del_by_offset(struct btree_trans *trans,
  92                                           struct bpos bucket,
  93                                           u64 bp_offset,
  94                                           struct bch_backpointer bp)
  95 {
  96         struct bch_fs *c = trans->c;
  97         struct btree_iter iter;
  98         struct bkey_s_c k;
  99         int ret;
 100
 101         if (bp_offset < BACKPOINTER_OFFSET_MAX) {
 102                 struct bch_backpointer *bps;
 103                 struct bkey_i_alloc_v4 *a;
 104                 unsigned i, nr;
 105
 106                 bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
 107                                      bucket,
 108                                      BTREE_ITER_INTENT|
 109                                      BTREE_ITER_SLOTS|
 110                                      BTREE_ITER_WITH_UPDATES);
 111                 k = bch2_btree_iter_peek_slot(&iter);
 112                 ret = bkey_err(k);
 113                 if (ret)
 114                         goto err;
 115
 116                 if (k.k->type != KEY_TYPE_alloc_v4) {
 117                         ret = -ENOENT;
 118                         goto err;
 119                 }
 120
 121                 a = bch2_alloc_to_v4_mut(trans, k);
 122                 ret = PTR_ERR_OR_ZERO(a);
 123                 if (ret)
 124                         goto err;
 125                 bps = alloc_v4_backpointers(&a->v);
 126                 nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 127
 128                 for (i = 0; i < nr; i++) {
 129                         if (bps[i].bucket_offset == bp_offset)
 130                                 goto found;
 131                         if (bps[i].bucket_offset > bp_offset)
 132                                 break;
 133                 }
 134
 135                 ret = -ENOENT;
 136                 goto err;
 137 found:
 138                 if (memcmp(&bps[i], &bp, sizeof(bp))) {
 139                         ret = -ENOENT;
 140                         goto err;
 141                 }
 142                 array_remove_item(bps, nr, i);
 143                 SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 144                 set_alloc_v4_u64s(a);
 145                 ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
 146         } else {
 147                 bp_offset -= BACKPOINTER_OFFSET_MAX;
 148
 149                 bch2_trans_iter_init(trans, &iter, BTREE_ID_backpointers,
 150                                      bucket_pos_to_bp(c, bucket, bp_offset),
 151                                      BTREE_ITER_INTENT|
 152                                      BTREE_ITER_SLOTS|
 153                                      BTREE_ITER_WITH_UPDATES);
 154                 k = bch2_btree_iter_peek_slot(&iter);
 155                 ret = bkey_err(k);
 156                 if (ret)
 157                         goto err;
 158
 159                 if (k.k->type != KEY_TYPE_backpointer ||
 160                     memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
 161                         ret = -ENOENT;
 162                         goto err;
 163                 }
 164
 165                 ret = bch2_btree_delete_at(trans, &iter, 0);
 166         }
 167 err:
 168         bch2_trans_iter_exit(trans, &iter);
 169         return ret;
 170 }
 171
 172 bool bch2_bucket_backpointer_del(struct btree_trans *trans,
 173                                  struct bkey_i_alloc_v4 *a,
 174                                  struct bch_backpointer bp)
 175 {
 176         struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
 177         unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
 178
 179         for (i = 0; i < nr; i++) {
 180                 int cmp = backpointer_cmp(bps[i], bp) ?:
 181                         memcmp(&bps[i], &bp, sizeof(bp));
 182                 if (!cmp) {
 183                         array_remove_item(bps, nr, i);
 184                         SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
 185                         set_alloc_v4_u64s(a);
 186                         return true;
 187                 }
 188                 if (cmp >= 0)
 189                         break;
 190         }
 191
 192         return false;
 193 }
 194
 195 static noinline int backpointer_mod_err(struct btree_trans *trans,
 196                                         struct bch_backpointer bp,
 197                                         struct bkey_s_c bp_k,
 198                                         struct bkey_s_c orig_k,
 199                                         bool insert)
 200 {
 201         struct bch_fs *c = trans->c;
 202         struct printbuf buf = PRINTBUF;
 203
 204         if (insert) {
 205                 prt_printf(&buf, "existing backpointer found when inserting ");
 206                 bch2_backpointer_to_text(&buf, &bp);
 207                 prt_newline(&buf);
 208                 printbuf_indent_add(&buf, 2);
 209
 210                 prt_printf(&buf, "found ");
 211                 bch2_bkey_val_to_text(&buf, c, bp_k);
 212                 prt_newline(&buf);
 213
 214                 prt_printf(&buf, "for ");
 215                 bch2_bkey_val_to_text(&buf, c, orig_k);
 216
 217                 bch_err(c, "%s", buf.buf);
 218         } else if (test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags)) {
 219                 prt_printf(&buf, "backpointer not found when deleting");
 220                 prt_newline(&buf);
 221                 printbuf_indent_add(&buf, 2);
 222
 223                 prt_printf(&buf, "searching for ");
 224                 bch2_backpointer_to_text(&buf, &bp);
 225                 prt_newline(&buf);
 226
 227                 prt_printf(&buf, "got ");
 228                 bch2_bkey_val_to_text(&buf, c, bp_k);
 229                 prt_newline(&buf);
 230
 231                 prt_printf(&buf, "for ");
 232                 bch2_bkey_val_to_text(&buf, c, orig_k);
 233
 234                 bch_err(c, "%s", buf.buf);
 235         }
 236
 237         printbuf_exit(&buf);
 238
 239         if (test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags)) {
 240                 bch2_inconsistent_error(c);
 241                 return -EIO;
 242         } else {
 243                 return 0;
 244         }
 245 }
 246
 247 int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 248                                 struct bkey_i_alloc_v4 *a,
 249                                 struct bch_backpointer bp,
 250                                 struct bkey_s_c orig_k,
 251                                 bool insert)
 252 {
 253         struct bch_fs *c = trans->c;
 254         struct bkey_i_backpointer *bp_k;
 255         struct btree_iter bp_iter;
 256         struct bkey_s_c k;
 257         int ret;
 258
 259         bp_k = bch2_trans_kmalloc_nomemzero(trans, sizeof(struct bkey_i_backpointer));
 260         ret = PTR_ERR_OR_ZERO(bp_k);
 261         if (ret)
 262                 return ret;
 263
 264         bkey_backpointer_init(&bp_k->k_i);
 265         bp_k->k.p = bucket_pos_to_bp(c, a->k.p, bp.bucket_offset);
 266         bp_k->v = bp;
 267
 268         if (!insert) {
 269                 bp_k->k.type = KEY_TYPE_deleted;
 270                 set_bkey_val_u64s(&bp_k->k, 0);
 271         }
 272
 273         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 274                              bucket_pos_to_bp(c, a->k.p, bp.bucket_offset),
 275                              BTREE_ITER_INTENT|
 276                              BTREE_ITER_SLOTS|
 277                              BTREE_ITER_WITH_UPDATES);
 278         k = bch2_btree_iter_peek_slot(&bp_iter);
 279         ret = bkey_err(k);
 280         if (ret)
 281                 goto err;
 282
 283         if (insert
 284             ? k.k->type
 285             : (k.k->type != KEY_TYPE_backpointer ||
 286                memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp)))) {
 287                 ret = backpointer_mod_err(trans, bp, k, orig_k, insert);
 288                 if (ret)
 289                         goto err;
 290         }
 291
 292         ret = bch2_trans_update(trans, &bp_iter, &bp_k->k_i, 0);
 293 err:
 294         bch2_trans_iter_exit(trans, &bp_iter);
 295         return ret;
 296 }
 297
 298 /*
 299  * Find the next backpointer >= *bp_offset:
 300  */
 301 int bch2_get_next_backpointer(struct btree_trans *trans,
 302                               struct bpos bucket, int gen,
 303                               u64 *bp_offset,
 304                               struct bch_backpointer *dst,
 305                               unsigned iter_flags)
 306 {
 307         struct bch_fs *c = trans->c;
 308         struct bpos bp_pos, bp_end_pos;
 309         struct btree_iter alloc_iter, bp_iter = { NULL };
 310         struct bkey_s_c k;
 311         struct bkey_s_c_alloc_v4 a;
 312         size_t i;
 313         int ret;
 314
 315         if (*bp_offset == U64_MAX)
 316                 return 0;
 317
 318         bp_pos = bucket_pos_to_bp(c, bucket,
 319                                   max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
 320         bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 321
 322         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 323                              bucket, BTREE_ITER_CACHED);
 324         k = bch2_btree_iter_peek_slot(&alloc_iter);
 325         ret = bkey_err(k);
 326         if (ret)
 327                 goto out;
 328
 329         if (k.k->type != KEY_TYPE_alloc_v4)
 330                 goto done;
 331
 332         a = bkey_s_c_to_alloc_v4(k);
 333         if (gen >= 0 && a.v->gen != gen)
 334                 goto done;
 335
 336         for (i = 0; i < BCH_ALLOC_V4_NR_BACKPOINTERS(a.v); i++) {
 337                 if (alloc_v4_backpointers_c(a.v)[i].bucket_offset < *bp_offset)
 338                         continue;
 339
 340                 *dst = alloc_v4_backpointers_c(a.v)[i];
 341                 *bp_offset = dst->bucket_offset;
 342                 goto out;
 343         }
 344
 345         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 346                                      bp_pos, 0, k, ret) {
 347                 if (bpos_ge(k.k->p, bp_end_pos))
 348                         break;
 349
 350                 if (k.k->type != KEY_TYPE_backpointer)
 351                         continue;
 352
 353                 *dst = *bkey_s_c_to_backpointer(k).v;
 354                 *bp_offset = dst->bucket_offset + BACKPOINTER_OFFSET_MAX;
 355                 goto out;
 356         }
 357 done:
 358         *bp_offset = U64_MAX;
 359 out:
 360         bch2_trans_iter_exit(trans, &bp_iter);
 361         bch2_trans_iter_exit(trans, &alloc_iter);
 362         return ret;
 363 }
 364
 365 static void backpointer_not_found(struct btree_trans *trans,
 366                                   struct bpos bucket,
 367                                   u64 bp_offset,
 368                                   struct bch_backpointer bp,
 369                                   struct bkey_s_c k,
 370                                   const char *thing_it_points_to)
 371 {
 372         struct bch_fs *c = trans->c;
 373         struct printbuf buf = PRINTBUF;
 374
 375         if (likely(!bch2_backpointers_no_use_write_buffer))
 376                 return;
 377
 378         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 379                    thing_it_points_to);
 380         prt_printf(&buf, "bucket: ");
 381         bch2_bpos_to_text(&buf, bucket);
 382         prt_printf(&buf, "\n  ");
 383
 384         if (bp_offset >= BACKPOINTER_OFFSET_MAX) {
 385                 struct bpos bp_pos =
 386                         bucket_pos_to_bp(c, bucket,
 387                                         bp_offset - BACKPOINTER_OFFSET_MAX);
 388                 prt_printf(&buf, "backpointer pos: ");
 389                 bch2_bpos_to_text(&buf, bp_pos);
 390                 prt_printf(&buf, "\n  ");
 391         }
 392
 393         bch2_backpointer_to_text(&buf, &bp);
 394         prt_printf(&buf, "\n  ");
 395         bch2_bkey_val_to_text(&buf, c, k);
 396         if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 397                 bch_err_ratelimited(c, "%s", buf.buf);
 398         else
 399                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 400
 401         printbuf_exit(&buf);
 402 }
 403
 404 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 405                                          struct btree_iter *iter,
 406                                          struct bpos bucket,
 407                                          u64 bp_offset,
 408                                          struct bch_backpointer bp)
 409 {
 410         struct bch_fs *c = trans->c;
 411         struct bkey_s_c k;
 412
 413         bch2_trans_node_iter_init(trans, iter,
 414                                   bp.btree_id,
 415                                   bp.pos,
 416                                   0,
 417                                   min(bp.level, c->btree_roots[bp.btree_id].level),
 418                                   0);
 419         k = bch2_btree_iter_peek_slot(iter);
 420         if (bkey_err(k)) {
 421                 bch2_trans_iter_exit(trans, iter);
 422                 return k;
 423         }
 424
 425         if (bp.level == c->btree_roots[bp.btree_id].level + 1)
 426                 k = bkey_i_to_s_c(&c->btree_roots[bp.btree_id].key);
 427
 428         if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 429                 return k;
 430
 431         bch2_trans_iter_exit(trans, iter);
 432
 433         if (unlikely(bch2_backpointers_no_use_write_buffer)) {
 434                 if (bp.level) {
 435                         struct btree *b;
 436
 437                         /*
 438                          * If a backpointer for a btree node wasn't found, it may be
 439                          * because it was overwritten by a new btree node that hasn't
 440                          * been written out yet - backpointer_get_node() checks for
 441                          * this:
 442                          */
 443                         b = bch2_backpointer_get_node(trans, iter, bucket, bp_offset, bp);
 444                         if (!IS_ERR_OR_NULL(b))
 445                                 return bkey_i_to_s_c(&b->key);
 446
 447                         bch2_trans_iter_exit(trans, iter);
 448
 449                         if (IS_ERR(b))
 450                                 return bkey_s_c_err(PTR_ERR(b));
 451                         return bkey_s_c_null;
 452                 }
 453
 454                 backpointer_not_found(trans, bucket, bp_offset, bp, k, "extent");
 455         }
 456
 457         return bkey_s_c_null;
 458 }
 459
 460 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 461                                         struct btree_iter *iter,
 462                                         struct bpos bucket,
 463                                         u64 bp_offset,
 464                                         struct bch_backpointer bp)
 465 {
 466         struct bch_fs *c = trans->c;
 467         struct btree *b;
 468
 469         BUG_ON(!bp.level);
 470
 471         bch2_trans_node_iter_init(trans, iter,
 472                                   bp.btree_id,
 473                                   bp.pos,
 474                                   0,
 475                                   bp.level - 1,
 476                                   0);
 477         b = bch2_btree_iter_peek_node(iter);
 478         if (IS_ERR(b))
 479                 goto err;
 480
 481         if (b && extent_matches_bp(c, bp.btree_id, bp.level,
 482                                    bkey_i_to_s_c(&b->key),
 483                                    bucket, bp))
 484                 return b;
 485
 486         if (b && btree_node_will_make_reachable(b)) {
 487                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 488         } else {
 489                 backpointer_not_found(trans, bucket, bp_offset, bp,
 490                                       bkey_i_to_s_c(&b->key), "btree node");
 491                 b = NULL;
 492         }
 493 err:
 494         bch2_trans_iter_exit(trans, iter);
 495         return b;
 496 }
 497
 498 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 499                                         struct bkey_s_c k)
 500 {
 501         struct bch_fs *c = trans->c;
 502         struct btree_iter alloc_iter = { NULL };
 503         struct bch_dev *ca;
 504         struct bkey_s_c alloc_k;
 505         struct printbuf buf = PRINTBUF;
 506         int ret = 0;
 507
 508         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 509                         "backpointer for mising device:\n%s",
 510                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 511                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 512                 goto out;
 513         }
 514
 515         ca = bch_dev_bkey_exists(c, k.k->p.inode);
 516
 517         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 518                              bp_pos_to_bucket(c, k.k->p), 0);
 519
 520         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 521         ret = bkey_err(alloc_k);
 522         if (ret)
 523                 goto out;
 524
 525         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 526                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 527                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 528                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 529                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 530                 goto out;
 531         }
 532 out:
 533 fsck_err:
 534         bch2_trans_iter_exit(trans, &alloc_iter);
 535         printbuf_exit(&buf);
 536         return ret;
 537 }
 538
 539 /* verify that every backpointer has a corresponding alloc key */
 540 int bch2_check_btree_backpointers(struct bch_fs *c)
 541 {
 542         struct btree_iter iter;
 543         struct bkey_s_c k;
 544
 545         return bch2_trans_run(c,
 546                 for_each_btree_key_commit(&trans, iter,
 547                         BTREE_ID_backpointers, POS_MIN, 0, k,
 548                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 549                   bch2_check_btree_backpointer(&trans, &iter, k)));
 550 }
 551
 552 static int check_bp_exists(struct btree_trans *trans,
 553                            struct bpos bucket_pos,
 554                            struct bch_backpointer bp,
 555                            struct bkey_s_c orig_k,
 556                            struct bpos bucket_start,
 557                            struct bpos bucket_end,
 558                            struct bpos *last_flushed_pos)
 559 {
 560         struct bch_fs *c = trans->c;
 561         struct btree_iter alloc_iter, bp_iter = { NULL };
 562         struct printbuf buf = PRINTBUF;
 563         struct bkey_s_c alloc_k, bp_k;
 564         int ret;
 565
 566         if (bpos_lt(bucket_pos, bucket_start) ||
 567             bpos_gt(bucket_pos, bucket_end))
 568                 return 0;
 569
 570         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, bucket_pos, 0);
 571         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 572         ret = bkey_err(alloc_k);
 573         if (ret)
 574                 goto err;
 575
 576         if (alloc_k.k->type == KEY_TYPE_alloc_v4) {
 577                 struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(alloc_k);
 578                 const struct bch_backpointer *bps = alloc_v4_backpointers_c(a.v);
 579                 unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(a.v);
 580
 581                 for (i = 0; i < nr; i++) {
 582                         int cmp = backpointer_cmp(bps[i], bp) ?:
 583                                 memcmp(&bps[i], &bp, sizeof(bp));
 584                         if (!cmp)
 585                                 goto out;
 586                         if (cmp >= 0)
 587                                 break;
 588                 }
 589         } else {
 590                 goto missing;
 591         }
 592
 593         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 594                              bucket_pos_to_bp(c, bucket_pos, bp.bucket_offset),
 595                              0);
 596         bp_k = bch2_btree_iter_peek_slot(&bp_iter);
 597         ret = bkey_err(bp_k);
 598         if (ret)
 599                 goto err;
 600
 601         if (bp_k.k->type != KEY_TYPE_backpointer ||
 602             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
 603                 if (!bpos_eq(*last_flushed_pos, orig_k.k->p)) {
 604                         *last_flushed_pos = orig_k.k->p;
 605                         ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 606                                 -BCH_ERR_transaction_restart_write_buffer_flush;
 607                         goto out;
 608                 }
 609                 goto missing;
 610         }
 611 out:
 612 err:
 613 fsck_err:
 614         bch2_trans_iter_exit(trans, &bp_iter);
 615         bch2_trans_iter_exit(trans, &alloc_iter);
 616         printbuf_exit(&buf);
 617         return ret;
 618 missing:
 619
 620         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 621                bch2_btree_ids[bp.btree_id], bp.level);
 622         bch2_bkey_val_to_text(&buf, c, orig_k);
 623         prt_printf(&buf, "\nbp pos ");
 624         bch2_bpos_to_text(&buf, bp_iter.pos);
 625
 626         if (c->sb.version < bcachefs_metadata_version_backpointers ||
 627             c->opts.reconstruct_alloc ||
 628             fsck_err(c, "%s", buf.buf)) {
 629                 struct bkey_i_alloc_v4 *a = bch2_alloc_to_v4_mut(trans, alloc_k);
 630
 631                 ret   = PTR_ERR_OR_ZERO(a) ?:
 632                         bch2_bucket_backpointer_mod(trans, a, bp, orig_k, true);
 633         }
 634
 635         goto out;
 636 }
 637
 638 static int check_extent_to_backpointers(struct btree_trans *trans,
 639                                         struct btree_iter *iter,
 640                                         struct bpos bucket_start,
 641                                         struct bpos bucket_end,
 642                                         struct bpos *last_flushed_pos)
 643 {
 644         struct bch_fs *c = trans->c;
 645         struct bkey_ptrs_c ptrs;
 646         const union bch_extent_entry *entry;
 647         struct extent_ptr_decoded p;
 648         struct bkey_s_c k;
 649         int ret;
 650
 651         k = bch2_btree_iter_peek_all_levels(iter);
 652         ret = bkey_err(k);
 653         if (ret)
 654                 return ret;
 655         if (!k.k)
 656                 return 0;
 657
 658         ptrs = bch2_bkey_ptrs_c(k);
 659         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 660                 struct bpos bucket_pos;
 661                 struct bch_backpointer bp;
 662
 663                 if (p.ptr.cached)
 664                         continue;
 665
 666                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 667                                       k, p, &bucket_pos, &bp);
 668
 669                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 670                                       bucket_start, bucket_end,
 671                                       last_flushed_pos);
 672                 if (ret)
 673                         return ret;
 674         }
 675
 676         return 0;
 677 }
 678
 679 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 680                                             enum btree_id btree_id,
 681                                             struct bpos bucket_start,
 682                                             struct bpos bucket_end,
 683                                             struct bpos *last_flushed_pos)
 684 {
 685         struct bch_fs *c = trans->c;
 686         struct btree_iter iter;
 687         struct btree *b;
 688         struct bkey_s_c k;
 689         struct bkey_ptrs_c ptrs;
 690         struct extent_ptr_decoded p;
 691         const union bch_extent_entry *entry;
 692         int ret;
 693
 694         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 695                                   c->btree_roots[btree_id].level, 0);
 696         b = bch2_btree_iter_peek_node(&iter);
 697         ret = PTR_ERR_OR_ZERO(b);
 698         if (ret)
 699                 goto err;
 700
 701         BUG_ON(b != btree_node_root(c, b));
 702
 703         k = bkey_i_to_s_c(&b->key);
 704         ptrs = bch2_bkey_ptrs_c(k);
 705         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 706                 struct bpos bucket_pos;
 707                 struct bch_backpointer bp;
 708
 709                 if (p.ptr.cached)
 710                         continue;
 711
 712                 bch2_extent_ptr_to_bp(c, iter.btree_id, iter.path->level + 1,
 713                                       k, p, &bucket_pos, &bp);
 714
 715                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 716                                       bucket_start, bucket_end,
 717                                       last_flushed_pos);
 718                 if (ret)
 719                         goto err;
 720         }
 721 err:
 722         bch2_trans_iter_exit(trans, &iter);
 723         return ret;
 724 }
 725
 726 static inline struct bbpos bp_to_bbpos(struct bch_backpointer bp)
 727 {
 728         return (struct bbpos) {
 729                 .btree  = bp.btree_id,
 730                 .pos    = bp.pos,
 731         };
 732 }
 733
 734 static size_t btree_nodes_fit_in_ram(struct bch_fs *c)
 735 {
 736         struct sysinfo i;
 737         u64 mem_bytes;
 738
 739         si_meminfo(&i);
 740         mem_bytes = i.totalram * i.mem_unit;
 741         return div_u64(mem_bytes >> 1, btree_bytes(c));
 742 }
 743
 744 int bch2_get_btree_in_memory_pos(struct btree_trans *trans,
 745                                  unsigned btree_leaf_mask,
 746                                  unsigned btree_interior_mask,
 747                                  struct bbpos start, struct bbpos *end)
 748 {
 749         struct btree_iter iter;
 750         struct bkey_s_c k;
 751         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 752         enum btree_id btree;
 753         int ret = 0;
 754
 755         for (btree = start.btree; btree < BTREE_ID_NR && !ret; btree++) {
 756                 unsigned depth = ((1U << btree) & btree_leaf_mask) ? 1 : 2;
 757
 758                 if (!((1U << btree) & btree_leaf_mask) &&
 759                     !((1U << btree) & btree_interior_mask))
 760                         continue;
 761
 762                 bch2_trans_node_iter_init(trans, &iter, btree,
 763                                           btree == start.btree ? start.pos : POS_MIN,
 764                                           0, depth, 0);
 765                 /*
 766                  * for_each_btree_key_contineu() doesn't check the return value
 767                  * from bch2_btree_iter_advance(), which is needed when
 768                  * iterating over interior nodes where we'll see keys at
 769                  * SPOS_MAX:
 770                  */
 771                 do {
 772                         k = __bch2_btree_iter_peek_and_restart(trans, &iter, 0);
 773                         ret = bkey_err(k);
 774                         if (!k.k || ret)
 775                                 break;
 776
 777                         --btree_nodes;
 778                         if (!btree_nodes) {
 779                                 *end = BBPOS(btree, k.k->p);
 780                                 bch2_trans_iter_exit(trans, &iter);
 781                                 return 0;
 782                         }
 783                 } while (bch2_btree_iter_advance(&iter));
 784                 bch2_trans_iter_exit(trans, &iter);
 785         }
 786
 787         *end = BBPOS_MAX;
 788         return ret;
 789 }
 790
 791 static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 792                                                    struct bpos bucket_start,
 793                                                    struct bpos bucket_end)
 794 {
 795         struct btree_iter iter;
 796         enum btree_id btree_id;
 797         struct bpos last_flushed_pos = SPOS_MAX;
 798         int ret = 0;
 799
 800         for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
 801                 unsigned depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 802
 803                 bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 804                                           depth,
 805                                           BTREE_ITER_ALL_LEVELS|
 806                                           BTREE_ITER_PREFETCH);
 807
 808                 do {
 809                         ret = commit_do(trans, NULL, NULL,
 810                                         BTREE_INSERT_LAZY_RW|
 811                                         BTREE_INSERT_NOFAIL,
 812                                         check_extent_to_backpointers(trans, &iter,
 813                                                                 bucket_start, bucket_end,
 814                                                                 &last_flushed_pos));
 815                         if (ret)
 816                                 break;
 817                 } while (!bch2_btree_iter_advance(&iter));
 818
 819                 bch2_trans_iter_exit(trans, &iter);
 820
 821                 if (ret)
 822                         break;
 823
 824                 ret = commit_do(trans, NULL, NULL,
 825                                 BTREE_INSERT_LAZY_RW|
 826                                 BTREE_INSERT_NOFAIL,
 827                                 check_btree_root_to_backpointers(trans, btree_id,
 828                                                         bucket_start, bucket_end,
 829                                                         &last_flushed_pos));
 830                 if (ret)
 831                         break;
 832         }
 833         return ret;
 834 }
 835
 836 static struct bpos bucket_pos_to_bp_safe(const struct bch_fs *c,
 837                                          struct bpos bucket)
 838 {
 839         return bch2_dev_exists2(c, bucket.inode)
 840                 ? bucket_pos_to_bp(c, bucket, 0)
 841                 : bucket;
 842 }
 843
 844 int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 845                                  struct bpos start, struct bpos *end)
 846 {
 847         struct btree_iter alloc_iter;
 848         struct btree_iter bp_iter;
 849         struct bkey_s_c alloc_k, bp_k;
 850         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 851         bool alloc_end = false, bp_end = false;
 852         int ret = 0;
 853
 854         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 855                                   start, 0, 1, 0);
 856         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 857                                   bucket_pos_to_bp_safe(trans->c, start), 0, 1, 0);
 858         while (1) {
 859                 alloc_k = !alloc_end
 860                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 861                         : bkey_s_c_null;
 862                 bp_k = !bp_end
 863                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 864                         : bkey_s_c_null;
 865
 866                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 867                 if ((!alloc_k.k && !bp_k.k) || ret) {
 868                         *end = SPOS_MAX;
 869                         break;
 870                 }
 871
 872                 --btree_nodes;
 873                 if (!btree_nodes) {
 874                         *end = alloc_k.k->p;
 875                         break;
 876                 }
 877
 878                 if (bpos_lt(alloc_iter.pos, SPOS_MAX) &&
 879                     bpos_lt(bucket_pos_to_bp_safe(trans->c, alloc_iter.pos), bp_iter.pos)) {
 880                         if (!bch2_btree_iter_advance(&alloc_iter))
 881                                 alloc_end = true;
 882                 } else {
 883                         if (!bch2_btree_iter_advance(&bp_iter))
 884                                 bp_end = true;
 885                 }
 886         }
 887         bch2_trans_iter_exit(trans, &bp_iter);
 888         bch2_trans_iter_exit(trans, &alloc_iter);
 889         return ret;
 890 }
 891
 892 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 893 {
 894         struct btree_trans trans;
 895         struct bpos start = POS_MIN, end;
 896         int ret;
 897
 898         bch2_trans_init(&trans, c, 0, 0);
 899         while (1) {
 900                 ret = bch2_get_alloc_in_memory_pos(&trans, start, &end);
 901                 if (ret)
 902                         break;
 903
 904                 if (bpos_eq(start, POS_MIN) && !bpos_eq(end, SPOS_MAX))
 905                         bch_verbose(c, "%s(): alloc info does not fit in ram, running in multiple passes with %zu nodes per pass",
 906                                     __func__, btree_nodes_fit_in_ram(c));
 907
 908                 if (!bpos_eq(start, POS_MIN) || !bpos_eq(end, SPOS_MAX)) {
 909                         struct printbuf buf = PRINTBUF;
 910
 911                         prt_str(&buf, "check_extents_to_backpointers(): ");
 912                         bch2_bpos_to_text(&buf, start);
 913                         prt_str(&buf, "-");
 914                         bch2_bpos_to_text(&buf, end);
 915
 916                         bch_verbose(c, "%s", buf.buf);
 917                         printbuf_exit(&buf);
 918                 }
 919
 920                 ret = bch2_check_extents_to_backpointers_pass(&trans, start, end);
 921                 if (ret || bpos_eq(end, SPOS_MAX))
 922                         break;
 923
 924                 start = bpos_successor(end);
 925         }
 926         bch2_trans_exit(&trans);
 927
 928         return ret;
 929 }
 930
 931 static int check_one_backpointer(struct btree_trans *trans,
 932                                  struct bpos bucket,
 933                                  u64 *bp_offset,
 934                                  struct bbpos start,
 935                                  struct bbpos end,
 936                                  struct bpos *last_flushed_pos)
 937 {
 938         struct bch_fs *c = trans->c;
 939         struct btree_iter iter;
 940         struct bch_backpointer bp;
 941         struct bbpos pos;
 942         struct bpos bp_pos;
 943         struct bkey_s_c k;
 944         struct printbuf buf = PRINTBUF;
 945         int ret;
 946
 947         ret = bch2_get_next_backpointer(trans, bucket, -1, bp_offset, &bp, 0);
 948         if (ret || *bp_offset == U64_MAX)
 949                 return ret;
 950
 951         pos = bp_to_bbpos(bp);
 952         if (bbpos_cmp(pos, start) < 0 ||
 953             bbpos_cmp(pos, end) > 0)
 954                 return 0;
 955
 956         k = bch2_backpointer_get_key(trans, &iter, bucket, *bp_offset, bp);
 957         ret = bkey_err(k);
 958         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 959                 return 0;
 960         if (ret)
 961                 return ret;
 962
 963         bp_pos = bucket_pos_to_bp(c, bucket,
 964                         max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
 965
 966         if (!k.k && !bpos_eq(*last_flushed_pos, bp_pos)) {
 967                 *last_flushed_pos = bp_pos;
 968                 pr_info("flushing at %llu:%llu",
 969                         last_flushed_pos->inode,
 970                         last_flushed_pos->offset);
 971
 972                 ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 973                         -BCH_ERR_transaction_restart_write_buffer_flush;
 974                 goto out;
 975         }
 976
 977         if (fsck_err_on(!k.k, c,
 978                         "%s backpointer points to missing extent\n%s",
 979                         *bp_offset < BACKPOINTER_OFFSET_MAX ? "alloc" : "btree",
 980                         (bch2_backpointer_to_text(&buf, &bp), buf.buf))) {
 981                 ret = bch2_backpointer_del_by_offset(trans, bucket, *bp_offset, bp);
 982                 if (ret == -ENOENT)
 983                         bch_err(c, "backpointer at %llu not found", *bp_offset);
 984         }
 985 out:
 986 fsck_err:
 987         bch2_trans_iter_exit(trans, &iter);
 988         printbuf_exit(&buf);
 989         return ret;
 990 }
 991
 992 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
 993                                                    struct bbpos start,
 994                                                    struct bbpos end)
 995 {
 996         struct btree_iter iter;
 997         struct bkey_s_c k;
 998         struct bpos last_flushed_pos = SPOS_MAX;
 999         int ret = 0;
1000
1001         for_each_btree_key(trans, iter, BTREE_ID_alloc, POS_MIN,
1002                            BTREE_ITER_PREFETCH, k, ret) {
1003                 u64 bp_offset = 0;
1004
1005                 while (!(ret = commit_do(trans, NULL, NULL,
1006                                          BTREE_INSERT_LAZY_RW|
1007                                          BTREE_INSERT_NOFAIL,
1008                                 check_one_backpointer(trans, iter.pos, &bp_offset,
1009                                                       start, end, &last_flushed_pos))) &&
1010                        bp_offset < U64_MAX)
1011                         bp_offset++;
1012
1013                 if (ret)
1014                         break;
1015         }
1016         bch2_trans_iter_exit(trans, &iter);
1017         return ret < 0 ? ret : 0;
1018 }
1019
1020 int bch2_check_backpointers_to_extents(struct bch_fs *c)
1021 {
1022         struct btree_trans trans;
1023         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
1024         int ret;
1025
1026         bch2_trans_init(&trans, c, 0, 0);
1027         while (1) {
1028                 ret = bch2_get_btree_in_memory_pos(&trans,
1029                                                    (1U << BTREE_ID_extents)|
1030                                                    (1U << BTREE_ID_reflink),
1031                                                    ~0,
1032                                                    start, &end);
1033                 if (ret)
1034                         break;
1035
1036                 if (!bbpos_cmp(start, BBPOS_MIN) &&
1037                     bbpos_cmp(end, BBPOS_MAX))
1038                         bch_verbose(c, "%s(): extents do not fit in ram, running in multiple passes with %zu nodes per pass",
1039                                     __func__, btree_nodes_fit_in_ram(c));
1040
1041                 if (bbpos_cmp(start, BBPOS_MIN) ||
1042                     bbpos_cmp(end, BBPOS_MAX)) {
1043                         struct printbuf buf = PRINTBUF;
1044
1045                         prt_str(&buf, "check_backpointers_to_extents(): ");
1046                         bch2_bbpos_to_text(&buf, start);
1047                         prt_str(&buf, "-");
1048                         bch2_bbpos_to_text(&buf, end);
1049
1050                         bch_verbose(c, "%s", buf.buf);
1051                         printbuf_exit(&buf);
1052                 }
1053
1054                 ret = bch2_check_backpointers_to_extents_pass(&trans, start, end);
1055                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
1056                         break;
1057
1058                 start = bbpos_successor(end);
1059         }
1060         bch2_trans_exit(&trans);
1061
1062         return ret;
1063 }