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 bpos *bp_pos_ret,
 305                                 struct bch_backpointer *dst,
 306                                 unsigned iter_flags)
 307 {
 308         struct bch_fs *c = trans->c;
 309         struct bpos bp_pos, bp_end_pos;
 310         struct btree_iter alloc_iter, bp_iter = { NULL };
 311         struct bkey_s_c k;
 312         struct bkey_s_c_alloc_v4 a;
 313         size_t i;
 314         int ret;
 315
 316         if (*bp_offset == U64_MAX)
 317                 return 0;
 318
 319         bp_pos = bucket_pos_to_bp(c, bucket,
 320                                   max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
 321         bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
 322
 323         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 324                              bucket, BTREE_ITER_CACHED);
 325         k = bch2_btree_iter_peek_slot(&alloc_iter);
 326         ret = bkey_err(k);
 327         if (ret)
 328                 goto out;
 329
 330         if (k.k->type != KEY_TYPE_alloc_v4)
 331                 goto done;
 332
 333         a = bkey_s_c_to_alloc_v4(k);
 334         if (gen >= 0 && a.v->gen != gen)
 335                 goto done;
 336
 337         for (i = 0; i < BCH_ALLOC_V4_NR_BACKPOINTERS(a.v); i++) {
 338                 if (alloc_v4_backpointers_c(a.v)[i].bucket_offset < *bp_offset)
 339                         continue;
 340
 341                 *dst = alloc_v4_backpointers_c(a.v)[i];
 342                 *bp_offset = dst->bucket_offset;
 343                 goto out;
 344         }
 345
 346         for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 347                                      bp_pos, 0, k, ret) {
 348                 if (bpos_ge(k.k->p, bp_end_pos))
 349                         break;
 350
 351                 if (k.k->type != KEY_TYPE_backpointer)
 352                         continue;
 353
 354                 *dst = *bkey_s_c_to_backpointer(k).v;
 355                 *bp_offset = dst->bucket_offset + BACKPOINTER_OFFSET_MAX;
 356                 *bp_pos_ret = k.k->p;
 357                 goto out;
 358         }
 359 done:
 360         *bp_offset = U64_MAX;
 361 out:
 362         bch2_trans_iter_exit(trans, &bp_iter);
 363         bch2_trans_iter_exit(trans, &alloc_iter);
 364         return ret;
 365 }
 366
 367 int bch2_get_next_backpointer(struct btree_trans *trans,
 368                               struct bpos bucket, int gen,
 369                               u64 *bp_offset,
 370                               struct bch_backpointer *dst,
 371                               unsigned iter_flags)
 372 {
 373         struct bpos bp_pos;
 374
 375         return __bch2_get_next_backpointer(trans, bucket, gen,
 376                                            bp_offset, &bp_pos,
 377                                            dst, iter_flags);
 378 }
 379
 380 static void backpointer_not_found(struct btree_trans *trans,
 381                                   struct bpos bucket,
 382                                   u64 bp_offset,
 383                                   struct bch_backpointer bp,
 384                                   struct bkey_s_c k,
 385                                   const char *thing_it_points_to)
 386 {
 387         struct bch_fs *c = trans->c;
 388         struct printbuf buf = PRINTBUF;
 389
 390         if (likely(!bch2_backpointers_no_use_write_buffer))
 391                 return;
 392
 393         prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 394                    thing_it_points_to);
 395         prt_printf(&buf, "bucket: ");
 396         bch2_bpos_to_text(&buf, bucket);
 397         prt_printf(&buf, "\n  ");
 398
 399         if (bp_offset >= BACKPOINTER_OFFSET_MAX) {
 400                 struct bpos bp_pos =
 401                         bucket_pos_to_bp(c, bucket,
 402                                         bp_offset - BACKPOINTER_OFFSET_MAX);
 403                 prt_printf(&buf, "backpointer pos: ");
 404                 bch2_bpos_to_text(&buf, bp_pos);
 405                 prt_printf(&buf, "\n  ");
 406         }
 407
 408         bch2_backpointer_to_text(&buf, &bp);
 409         prt_printf(&buf, "\n  ");
 410         bch2_bkey_val_to_text(&buf, c, k);
 411         if (!test_bit(BCH_FS_CHECK_BACKPOINTERS_DONE, &c->flags))
 412                 bch_err_ratelimited(c, "%s", buf.buf);
 413         else
 414                 bch2_trans_inconsistent(trans, "%s", buf.buf);
 415
 416         printbuf_exit(&buf);
 417 }
 418
 419 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 420                                          struct btree_iter *iter,
 421                                          struct bpos bucket,
 422                                          u64 bp_offset,
 423                                          struct bch_backpointer bp)
 424 {
 425         struct bch_fs *c = trans->c;
 426         struct bkey_s_c k;
 427
 428         bch2_trans_node_iter_init(trans, iter,
 429                                   bp.btree_id,
 430                                   bp.pos,
 431                                   0,
 432                                   min(bp.level, c->btree_roots[bp.btree_id].level),
 433                                   0);
 434         k = bch2_btree_iter_peek_slot(iter);
 435         if (bkey_err(k)) {
 436                 bch2_trans_iter_exit(trans, iter);
 437                 return k;
 438         }
 439
 440         if (bp.level == c->btree_roots[bp.btree_id].level + 1)
 441                 k = bkey_i_to_s_c(&c->btree_roots[bp.btree_id].key);
 442
 443         if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
 444                 return k;
 445
 446         bch2_trans_iter_exit(trans, iter);
 447
 448         if (unlikely(bch2_backpointers_no_use_write_buffer)) {
 449                 if (bp.level) {
 450                         struct btree *b;
 451
 452                         /*
 453                          * If a backpointer for a btree node wasn't found, it may be
 454                          * because it was overwritten by a new btree node that hasn't
 455                          * been written out yet - backpointer_get_node() checks for
 456                          * this:
 457                          */
 458                         b = bch2_backpointer_get_node(trans, iter, bucket, bp_offset, bp);
 459                         if (!IS_ERR_OR_NULL(b))
 460                                 return bkey_i_to_s_c(&b->key);
 461
 462                         bch2_trans_iter_exit(trans, iter);
 463
 464                         if (IS_ERR(b))
 465                                 return bkey_s_c_err(PTR_ERR(b));
 466                         return bkey_s_c_null;
 467                 }
 468
 469                 backpointer_not_found(trans, bucket, bp_offset, bp, k, "extent");
 470         }
 471
 472         return bkey_s_c_null;
 473 }
 474
 475 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 476                                         struct btree_iter *iter,
 477                                         struct bpos bucket,
 478                                         u64 bp_offset,
 479                                         struct bch_backpointer bp)
 480 {
 481         struct bch_fs *c = trans->c;
 482         struct btree *b;
 483
 484         BUG_ON(!bp.level);
 485
 486         bch2_trans_node_iter_init(trans, iter,
 487                                   bp.btree_id,
 488                                   bp.pos,
 489                                   0,
 490                                   bp.level - 1,
 491                                   0);
 492         b = bch2_btree_iter_peek_node(iter);
 493         if (IS_ERR(b))
 494                 goto err;
 495
 496         if (b && extent_matches_bp(c, bp.btree_id, bp.level,
 497                                    bkey_i_to_s_c(&b->key),
 498                                    bucket, bp))
 499                 return b;
 500
 501         if (b && btree_node_will_make_reachable(b)) {
 502                 b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 503         } else {
 504                 backpointer_not_found(trans, bucket, bp_offset, bp,
 505                                       bkey_i_to_s_c(&b->key), "btree node");
 506                 b = NULL;
 507         }
 508 err:
 509         bch2_trans_iter_exit(trans, iter);
 510         return b;
 511 }
 512
 513 static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_iter *bp_iter,
 514                                         struct bkey_s_c k)
 515 {
 516         struct bch_fs *c = trans->c;
 517         struct btree_iter alloc_iter = { NULL };
 518         struct bch_dev *ca;
 519         struct bkey_s_c alloc_k;
 520         struct printbuf buf = PRINTBUF;
 521         int ret = 0;
 522
 523         if (fsck_err_on(!bch2_dev_exists2(c, k.k->p.inode), c,
 524                         "backpointer for mising device:\n%s",
 525                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
 526                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 527                 goto out;
 528         }
 529
 530         ca = bch_dev_bkey_exists(c, k.k->p.inode);
 531
 532         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 533                              bp_pos_to_bucket(c, k.k->p), 0);
 534
 535         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 536         ret = bkey_err(alloc_k);
 537         if (ret)
 538                 goto out;
 539
 540         if (fsck_err_on(alloc_k.k->type != KEY_TYPE_alloc_v4, c,
 541                         "backpointer for nonexistent alloc key: %llu:%llu:0\n%s",
 542                         alloc_iter.pos.inode, alloc_iter.pos.offset,
 543                         (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
 544                 ret = bch2_btree_delete_at(trans, bp_iter, 0);
 545                 goto out;
 546         }
 547 out:
 548 fsck_err:
 549         bch2_trans_iter_exit(trans, &alloc_iter);
 550         printbuf_exit(&buf);
 551         return ret;
 552 }
 553
 554 /* verify that every backpointer has a corresponding alloc key */
 555 int bch2_check_btree_backpointers(struct bch_fs *c)
 556 {
 557         struct btree_iter iter;
 558         struct bkey_s_c k;
 559
 560         return bch2_trans_run(c,
 561                 for_each_btree_key_commit(&trans, iter,
 562                         BTREE_ID_backpointers, POS_MIN, 0, k,
 563                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
 564                   bch2_check_btree_backpointer(&trans, &iter, k)));
 565 }
 566
 567 struct bpos_level {
 568         unsigned        level;
 569         struct bpos     pos;
 570 };
 571
 572 static int check_bp_exists(struct btree_trans *trans,
 573                            struct bpos bucket_pos,
 574                            struct bch_backpointer bp,
 575                            struct bkey_s_c orig_k,
 576                            struct bpos bucket_start,
 577                            struct bpos bucket_end,
 578                            struct bpos_level *last_flushed)
 579 {
 580         struct bch_fs *c = trans->c;
 581         struct btree_iter alloc_iter, bp_iter = { NULL };
 582         struct printbuf buf = PRINTBUF;
 583         struct bkey_s_c alloc_k, bp_k;
 584         int ret;
 585
 586         if (bpos_lt(bucket_pos, bucket_start) ||
 587             bpos_gt(bucket_pos, bucket_end))
 588                 return 0;
 589
 590         bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, bucket_pos, 0);
 591         alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
 592         ret = bkey_err(alloc_k);
 593         if (ret)
 594                 goto err;
 595
 596         if (alloc_k.k->type == KEY_TYPE_alloc_v4) {
 597                 struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(alloc_k);
 598                 const struct bch_backpointer *bps = alloc_v4_backpointers_c(a.v);
 599                 unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(a.v);
 600
 601                 for (i = 0; i < nr; i++) {
 602                         int cmp = backpointer_cmp(bps[i], bp) ?:
 603                                 memcmp(&bps[i], &bp, sizeof(bp));
 604                         if (!cmp)
 605                                 goto out;
 606                         if (cmp >= 0)
 607                                 break;
 608                 }
 609         } else {
 610                 goto missing;
 611         }
 612
 613         bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 614                              bucket_pos_to_bp(c, bucket_pos, bp.bucket_offset),
 615                              0);
 616         bp_k = bch2_btree_iter_peek_slot(&bp_iter);
 617         ret = bkey_err(bp_k);
 618         if (ret)
 619                 goto err;
 620
 621         if (bp_k.k->type != KEY_TYPE_backpointer ||
 622             memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
 623                 if (last_flushed->level != bp.level ||
 624                     !bpos_eq(last_flushed->pos, orig_k.k->p)) {
 625                         last_flushed->level = bp.level;
 626                         last_flushed->pos = orig_k.k->p;
 627
 628                         ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 629                                 -BCH_ERR_transaction_restart_write_buffer_flush;
 630                         goto out;
 631                 }
 632                 goto missing;
 633         }
 634 out:
 635 err:
 636 fsck_err:
 637         bch2_trans_iter_exit(trans, &bp_iter);
 638         bch2_trans_iter_exit(trans, &alloc_iter);
 639         printbuf_exit(&buf);
 640         return ret;
 641 missing:
 642
 643         prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 644                bch2_btree_ids[bp.btree_id], bp.level);
 645         bch2_bkey_val_to_text(&buf, c, orig_k);
 646         prt_printf(&buf, "\nbp pos ");
 647         bch2_bpos_to_text(&buf, bp_iter.pos);
 648
 649         if (c->sb.version < bcachefs_metadata_version_backpointers ||
 650             c->opts.reconstruct_alloc ||
 651             fsck_err(c, "%s", buf.buf)) {
 652                 struct bkey_i_alloc_v4 *a = bch2_alloc_to_v4_mut(trans, alloc_k);
 653
 654                 ret   = PTR_ERR_OR_ZERO(a) ?:
 655                         bch2_bucket_backpointer_mod(trans, a, bp, orig_k, true);
 656         }
 657
 658         goto out;
 659 }
 660
 661 static int check_extent_to_backpointers(struct btree_trans *trans,
 662                                         struct btree_iter *iter,
 663                                         struct bpos bucket_start,
 664                                         struct bpos bucket_end,
 665                                         struct bpos_level *last_flushed)
 666 {
 667         struct bch_fs *c = trans->c;
 668         struct bkey_ptrs_c ptrs;
 669         const union bch_extent_entry *entry;
 670         struct extent_ptr_decoded p;
 671         struct bkey_s_c k;
 672         int ret;
 673
 674         k = bch2_btree_iter_peek_all_levels(iter);
 675         ret = bkey_err(k);
 676         if (ret)
 677                 return ret;
 678         if (!k.k)
 679                 return 0;
 680
 681         ptrs = bch2_bkey_ptrs_c(k);
 682         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 683                 struct bpos bucket_pos;
 684                 struct bch_backpointer bp;
 685
 686                 if (p.ptr.cached)
 687                         continue;
 688
 689                 bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 690                                       k, p, &bucket_pos, &bp);
 691
 692                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 693                                       bucket_start, bucket_end,
 694                                       last_flushed);
 695                 if (ret)
 696                         return ret;
 697         }
 698
 699         return 0;
 700 }
 701
 702 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 703                                             enum btree_id btree_id,
 704                                             struct bpos bucket_start,
 705                                             struct bpos bucket_end,
 706                                             struct bpos_level *last_flushed)
 707 {
 708         struct bch_fs *c = trans->c;
 709         struct btree_iter iter;
 710         struct btree *b;
 711         struct bkey_s_c k;
 712         struct bkey_ptrs_c ptrs;
 713         struct extent_ptr_decoded p;
 714         const union bch_extent_entry *entry;
 715         int ret;
 716
 717         bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 718                                   c->btree_roots[btree_id].level, 0);
 719         b = bch2_btree_iter_peek_node(&iter);
 720         ret = PTR_ERR_OR_ZERO(b);
 721         if (ret)
 722                 goto err;
 723
 724         BUG_ON(b != btree_node_root(c, b));
 725
 726         k = bkey_i_to_s_c(&b->key);
 727         ptrs = bch2_bkey_ptrs_c(k);
 728         bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 729                 struct bpos bucket_pos;
 730                 struct bch_backpointer bp;
 731
 732                 if (p.ptr.cached)
 733                         continue;
 734
 735                 bch2_extent_ptr_to_bp(c, iter.btree_id, b->c.level + 1,
 736                                       k, p, &bucket_pos, &bp);
 737
 738                 ret = check_bp_exists(trans, bucket_pos, bp, k,
 739                                       bucket_start, bucket_end,
 740                                       last_flushed);
 741                 if (ret)
 742                         goto err;
 743         }
 744 err:
 745         bch2_trans_iter_exit(trans, &iter);
 746         return ret;
 747 }
 748
 749 static inline struct bbpos bp_to_bbpos(struct bch_backpointer bp)
 750 {
 751         return (struct bbpos) {
 752                 .btree  = bp.btree_id,
 753                 .pos    = bp.pos,
 754         };
 755 }
 756
 757 static size_t btree_nodes_fit_in_ram(struct bch_fs *c)
 758 {
 759         struct sysinfo i;
 760         u64 mem_bytes;
 761
 762         si_meminfo(&i);
 763         mem_bytes = i.totalram * i.mem_unit;
 764         return div_u64(mem_bytes >> 1, btree_bytes(c));
 765 }
 766
 767 int bch2_get_btree_in_memory_pos(struct btree_trans *trans,
 768                                  unsigned btree_leaf_mask,
 769                                  unsigned btree_interior_mask,
 770                                  struct bbpos start, struct bbpos *end)
 771 {
 772         struct btree_iter iter;
 773         struct bkey_s_c k;
 774         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 775         enum btree_id btree;
 776         int ret = 0;
 777
 778         for (btree = start.btree; btree < BTREE_ID_NR && !ret; btree++) {
 779                 unsigned depth = ((1U << btree) & btree_leaf_mask) ? 1 : 2;
 780
 781                 if (!((1U << btree) & btree_leaf_mask) &&
 782                     !((1U << btree) & btree_interior_mask))
 783                         continue;
 784
 785                 bch2_trans_node_iter_init(trans, &iter, btree,
 786                                           btree == start.btree ? start.pos : POS_MIN,
 787                                           0, depth, 0);
 788                 /*
 789                  * for_each_btree_key_contineu() doesn't check the return value
 790                  * from bch2_btree_iter_advance(), which is needed when
 791                  * iterating over interior nodes where we'll see keys at
 792                  * SPOS_MAX:
 793                  */
 794                 do {
 795                         k = __bch2_btree_iter_peek_and_restart(trans, &iter, 0);
 796                         ret = bkey_err(k);
 797                         if (!k.k || ret)
 798                                 break;
 799
 800                         --btree_nodes;
 801                         if (!btree_nodes) {
 802                                 *end = BBPOS(btree, k.k->p);
 803                                 bch2_trans_iter_exit(trans, &iter);
 804                                 return 0;
 805                         }
 806                 } while (bch2_btree_iter_advance(&iter));
 807                 bch2_trans_iter_exit(trans, &iter);
 808         }
 809
 810         *end = BBPOS_MAX;
 811         return ret;
 812 }
 813
 814 static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 815                                                    struct bpos bucket_start,
 816                                                    struct bpos bucket_end)
 817 {
 818         struct btree_iter iter;
 819         enum btree_id btree_id;
 820         struct bpos_level last_flushed = { UINT_MAX };
 821         int ret = 0;
 822
 823         for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
 824                 unsigned depth = btree_type_has_ptrs(btree_id) ? 0 : 1;
 825
 826                 bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN, 0,
 827                                           depth,
 828                                           BTREE_ITER_ALL_LEVELS|
 829                                           BTREE_ITER_PREFETCH);
 830
 831                 do {
 832                         ret = commit_do(trans, NULL, NULL,
 833                                         BTREE_INSERT_LAZY_RW|
 834                                         BTREE_INSERT_NOFAIL,
 835                                         check_extent_to_backpointers(trans, &iter,
 836                                                                 bucket_start, bucket_end,
 837                                                                 &last_flushed));
 838                         if (ret)
 839                                 break;
 840                 } while (!bch2_btree_iter_advance(&iter));
 841
 842                 bch2_trans_iter_exit(trans, &iter);
 843
 844                 if (ret)
 845                         break;
 846
 847                 ret = commit_do(trans, NULL, NULL,
 848                                 BTREE_INSERT_LAZY_RW|
 849                                 BTREE_INSERT_NOFAIL,
 850                                 check_btree_root_to_backpointers(trans, btree_id,
 851                                                         bucket_start, bucket_end,
 852                                                         &last_flushed));
 853                 if (ret)
 854                         break;
 855         }
 856         return ret;
 857 }
 858
 859 static struct bpos bucket_pos_to_bp_safe(const struct bch_fs *c,
 860                                          struct bpos bucket)
 861 {
 862         return bch2_dev_exists2(c, bucket.inode)
 863                 ? bucket_pos_to_bp(c, bucket, 0)
 864                 : bucket;
 865 }
 866
 867 int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 868                                  struct bpos start, struct bpos *end)
 869 {
 870         struct btree_iter alloc_iter;
 871         struct btree_iter bp_iter;
 872         struct bkey_s_c alloc_k, bp_k;
 873         size_t btree_nodes = btree_nodes_fit_in_ram(trans->c);
 874         bool alloc_end = false, bp_end = false;
 875         int ret = 0;
 876
 877         bch2_trans_node_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
 878                                   start, 0, 1, 0);
 879         bch2_trans_node_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
 880                                   bucket_pos_to_bp_safe(trans->c, start), 0, 1, 0);
 881         while (1) {
 882                 alloc_k = !alloc_end
 883                         ? __bch2_btree_iter_peek_and_restart(trans, &alloc_iter, 0)
 884                         : bkey_s_c_null;
 885                 bp_k = !bp_end
 886                         ? __bch2_btree_iter_peek_and_restart(trans, &bp_iter, 0)
 887                         : bkey_s_c_null;
 888
 889                 ret = bkey_err(alloc_k) ?: bkey_err(bp_k);
 890                 if ((!alloc_k.k && !bp_k.k) || ret) {
 891                         *end = SPOS_MAX;
 892                         break;
 893                 }
 894
 895                 --btree_nodes;
 896                 if (!btree_nodes) {
 897                         *end = alloc_k.k->p;
 898                         break;
 899                 }
 900
 901                 if (bpos_lt(alloc_iter.pos, SPOS_MAX) &&
 902                     bpos_lt(bucket_pos_to_bp_safe(trans->c, alloc_iter.pos), bp_iter.pos)) {
 903                         if (!bch2_btree_iter_advance(&alloc_iter))
 904                                 alloc_end = true;
 905                 } else {
 906                         if (!bch2_btree_iter_advance(&bp_iter))
 907                                 bp_end = true;
 908                 }
 909         }
 910         bch2_trans_iter_exit(trans, &bp_iter);
 911         bch2_trans_iter_exit(trans, &alloc_iter);
 912         return ret;
 913 }
 914
 915 int bch2_check_extents_to_backpointers(struct bch_fs *c)
 916 {
 917         struct btree_trans trans;
 918         struct bpos start = POS_MIN, end;
 919         int ret;
 920
 921         bch2_trans_init(&trans, c, 0, 0);
 922         while (1) {
 923                 ret = bch2_get_alloc_in_memory_pos(&trans, start, &end);
 924                 if (ret)
 925                         break;
 926
 927                 if (bpos_eq(start, POS_MIN) && !bpos_eq(end, SPOS_MAX))
 928                         bch_verbose(c, "%s(): alloc info does not fit in ram, running in multiple passes with %zu nodes per pass",
 929                                     __func__, btree_nodes_fit_in_ram(c));
 930
 931                 if (!bpos_eq(start, POS_MIN) || !bpos_eq(end, SPOS_MAX)) {
 932                         struct printbuf buf = PRINTBUF;
 933
 934                         prt_str(&buf, "check_extents_to_backpointers(): ");
 935                         bch2_bpos_to_text(&buf, start);
 936                         prt_str(&buf, "-");
 937                         bch2_bpos_to_text(&buf, end);
 938
 939                         bch_verbose(c, "%s", buf.buf);
 940                         printbuf_exit(&buf);
 941                 }
 942
 943                 ret = bch2_check_extents_to_backpointers_pass(&trans, start, end);
 944                 if (ret || bpos_eq(end, SPOS_MAX))
 945                         break;
 946
 947                 start = bpos_successor(end);
 948         }
 949         bch2_trans_exit(&trans);
 950
 951         return ret;
 952 }
 953
 954 static int check_one_backpointer(struct btree_trans *trans,
 955                                  struct bpos bucket,
 956                                  u64 *bp_offset,
 957                                  struct bbpos start,
 958                                  struct bbpos end,
 959                                  struct bpos *last_flushed_pos)
 960 {
 961         struct bch_fs *c = trans->c;
 962         struct btree_iter iter;
 963         struct bch_backpointer bp;
 964         struct bbpos pos;
 965         struct bpos bp_pos;
 966         struct bkey_s_c k;
 967         struct printbuf buf = PRINTBUF;
 968         int ret;
 969
 970         ret = __bch2_get_next_backpointer(trans, bucket, -1, bp_offset, &bp_pos, &bp, 0);
 971         if (ret || *bp_offset == U64_MAX)
 972                 return ret;
 973
 974         pos = bp_to_bbpos(bp);
 975         if (bbpos_cmp(pos, start) < 0 ||
 976             bbpos_cmp(pos, end) > 0)
 977                 return 0;
 978
 979         k = bch2_backpointer_get_key(trans, &iter, bucket, *bp_offset, bp);
 980         ret = bkey_err(k);
 981         if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 982                 return 0;
 983         if (ret)
 984                 return ret;
 985
 986         if (!k.k && !bpos_eq(*last_flushed_pos, bp_pos)) {
 987                 *last_flushed_pos = bp_pos;
 988                 ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 989                         -BCH_ERR_transaction_restart_write_buffer_flush;
 990                 goto out;
 991         }
 992
 993         if (fsck_err_on(!k.k, c,
 994                         "backpointer for %llu:%llu:%llu (btree pos %llu:%llu) points to missing extent\n  %s",
 995                         bucket.inode, bucket.offset, (u64) bp.bucket_offset,
 996                         bp_pos.inode, bp_pos.offset,
 997                         (bch2_backpointer_to_text(&buf, &bp), buf.buf))) {
 998                 ret = bch2_backpointer_del_by_offset(trans, bucket, *bp_offset, bp);
 999                 if (ret == -ENOENT)
1000                         bch_err(c, "backpointer at %llu not found", *bp_offset);
1001         }
1002 out:
1003 fsck_err:
1004         bch2_trans_iter_exit(trans, &iter);
1005         printbuf_exit(&buf);
1006         return ret;
1007 }
1008
1009 static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
1010                                                    struct bbpos start,
1011                                                    struct bbpos end)
1012 {
1013         struct btree_iter iter;
1014         struct bkey_s_c k;
1015         struct bpos last_flushed_pos = SPOS_MAX;
1016         int ret = 0;
1017
1018         for_each_btree_key(trans, iter, BTREE_ID_alloc, POS_MIN,
1019                            BTREE_ITER_PREFETCH, k, ret) {
1020                 u64 bp_offset = 0;
1021
1022                 while (!(ret = commit_do(trans, NULL, NULL,
1023                                          BTREE_INSERT_LAZY_RW|
1024                                          BTREE_INSERT_NOFAIL,
1025                                 check_one_backpointer(trans, iter.pos, &bp_offset,
1026                                                       start, end, &last_flushed_pos))) &&
1027                        bp_offset < U64_MAX)
1028                         bp_offset++;
1029
1030                 if (ret)
1031                         break;
1032         }
1033         bch2_trans_iter_exit(trans, &iter);
1034         return ret < 0 ? ret : 0;
1035 }
1036
1037 int bch2_check_backpointers_to_extents(struct bch_fs *c)
1038 {
1039         struct btree_trans trans;
1040         struct bbpos start = (struct bbpos) { .btree = 0, .pos = POS_MIN, }, end;
1041         int ret;
1042
1043         bch2_trans_init(&trans, c, 0, 0);
1044         while (1) {
1045                 ret = bch2_get_btree_in_memory_pos(&trans,
1046                                                    (1U << BTREE_ID_extents)|
1047                                                    (1U << BTREE_ID_reflink),
1048                                                    ~0,
1049                                                    start, &end);
1050                 if (ret)
1051                         break;
1052
1053                 if (!bbpos_cmp(start, BBPOS_MIN) &&
1054                     bbpos_cmp(end, BBPOS_MAX))
1055                         bch_verbose(c, "%s(): extents do not fit in ram, running in multiple passes with %zu nodes per pass",
1056                                     __func__, btree_nodes_fit_in_ram(c));
1057
1058                 if (bbpos_cmp(start, BBPOS_MIN) ||
1059                     bbpos_cmp(end, BBPOS_MAX)) {
1060                         struct printbuf buf = PRINTBUF;
1061
1062                         prt_str(&buf, "check_backpointers_to_extents(): ");
1063                         bch2_bbpos_to_text(&buf, start);
1064                         prt_str(&buf, "-");
1065                         bch2_bbpos_to_text(&buf, end);
1066
1067                         bch_verbose(c, "%s", buf.buf);
1068                         printbuf_exit(&buf);
1069                 }
1070
1071                 ret = bch2_check_backpointers_to_extents_pass(&trans, start, end);
1072                 if (ret || !bbpos_cmp(end, BBPOS_MAX))
1073                         break;
1074
1075                 start = bbpos_successor(end);
1076         }
1077         bch2_trans_exit(&trans);
1078
1079         return ret;
1080 }