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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_buf.h"
   5 #include "btree_update.h"
   6 #include "darray.h"
   7 #include "dirent.h"
   8 #include "error.h"
   9 #include "fs-common.h"
  10 #include "fsck.h"
  11 #include "inode.h"
  12 #include "keylist.h"
  13 #include "subvolume.h"
  14 #include "super.h"
  15 #include "xattr.h"
  16
  17 #include <linux/bsearch.h>
  18 #include <linux/dcache.h> /* struct qstr */
  19
  20 #define QSTR(n) { { { .len = strlen(n) } }, .name = n }
  21
  22 /*
  23  * XXX: this is handling transaction restarts without returning
  24  * -BCH_ERR_transaction_restart_nested, this is not how we do things anymore:
  25  */
  26 static s64 bch2_count_inode_sectors(struct btree_trans *trans, u64 inum,
  27                                     u32 snapshot)
  28 {
  29         struct btree_iter iter;
  30         struct bkey_s_c k;
  31         u64 sectors = 0;
  32         int ret;
  33
  34         for_each_btree_key(trans, iter, BTREE_ID_extents,
  35                            SPOS(inum, 0, snapshot), 0, k, ret) {
  36                 if (k.k->p.inode != inum)
  37                         break;
  38
  39                 if (bkey_extent_is_allocation(k.k))
  40                         sectors += k.k->size;
  41         }
  42
  43         bch2_trans_iter_exit(trans, &iter);
  44
  45         return ret ?: sectors;
  46 }
  47
  48 static s64 bch2_count_subdirs(struct btree_trans *trans, u64 inum,
  49                                     u32 snapshot)
  50 {
  51         struct btree_iter iter;
  52         struct bkey_s_c k;
  53         struct bkey_s_c_dirent d;
  54         u64 subdirs = 0;
  55         int ret;
  56
  57         for_each_btree_key(trans, iter, BTREE_ID_dirents,
  58                            SPOS(inum, 0, snapshot), 0, k, ret) {
  59                 if (k.k->p.inode != inum)
  60                         break;
  61
  62                 if (k.k->type != KEY_TYPE_dirent)
  63                         continue;
  64
  65                 d = bkey_s_c_to_dirent(k);
  66                 if (d.v->d_type == DT_DIR)
  67                         subdirs++;
  68         }
  69
  70         bch2_trans_iter_exit(trans, &iter);
  71
  72         return ret ?: subdirs;
  73 }
  74
  75 static int __snapshot_lookup_subvol(struct btree_trans *trans, u32 snapshot,
  76                                     u32 *subvol)
  77 {
  78         struct btree_iter iter;
  79         struct bkey_s_c k;
  80         int ret;
  81
  82         bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,
  83                              POS(0, snapshot), 0);
  84         k = bch2_btree_iter_peek_slot(&iter);
  85         ret = bkey_err(k);
  86         if (ret)
  87                 goto err;
  88
  89         if (k.k->type != KEY_TYPE_snapshot) {
  90                 bch_err(trans->c, "snapshot %u not fonud", snapshot);
  91                 ret = -ENOENT;
  92                 goto err;
  93         }
  94
  95         *subvol = le32_to_cpu(bkey_s_c_to_snapshot(k).v->subvol);
  96 err:
  97         bch2_trans_iter_exit(trans, &iter);
  98         return ret;
  99
 100 }
 101
 102 static int __subvol_lookup(struct btree_trans *trans, u32 subvol,
 103                            u32 *snapshot, u64 *inum)
 104 {
 105         struct bch_subvolume s;
 106         int ret;
 107
 108         ret = bch2_subvolume_get(trans, subvol, false, 0, &s);
 109
 110         *snapshot = le32_to_cpu(s.snapshot);
 111         *inum = le64_to_cpu(s.inode);
 112         return ret;
 113 }
 114
 115 static int subvol_lookup(struct btree_trans *trans, u32 subvol,
 116                          u32 *snapshot, u64 *inum)
 117 {
 118         return lockrestart_do(trans, __subvol_lookup(trans, subvol, snapshot, inum));
 119 }
 120
 121 static int lookup_first_inode(struct btree_trans *trans, u64 inode_nr,
 122                               struct bch_inode_unpacked *inode)
 123 {
 124         struct btree_iter iter;
 125         struct bkey_s_c k;
 126         int ret;
 127
 128         bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes,
 129                              POS(0, inode_nr),
 130                              BTREE_ITER_ALL_SNAPSHOTS);
 131         k = bch2_btree_iter_peek(&iter);
 132         ret = bkey_err(k);
 133         if (ret)
 134                 goto err;
 135
 136         if (!k.k || bkey_cmp(k.k->p, POS(0, inode_nr))) {
 137                 ret = -ENOENT;
 138                 goto err;
 139         }
 140
 141         ret = bch2_inode_unpack(k, inode);
 142 err:
 143         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
 144                 bch_err(trans->c, "error fetching inode %llu: %s",
 145                         inode_nr, bch2_err_str(ret));
 146         bch2_trans_iter_exit(trans, &iter);
 147         return ret;
 148 }
 149
 150 static int __lookup_inode(struct btree_trans *trans, u64 inode_nr,
 151                           struct bch_inode_unpacked *inode,
 152                           u32 *snapshot)
 153 {
 154         struct btree_iter iter;
 155         struct bkey_s_c k;
 156         int ret;
 157
 158         bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes,
 159                              SPOS(0, inode_nr, *snapshot), 0);
 160         k = bch2_btree_iter_peek_slot(&iter);
 161         ret = bkey_err(k);
 162         if (ret)
 163                 goto err;
 164
 165         ret = bkey_is_inode(k.k)
 166                 ? bch2_inode_unpack(k, inode)
 167                 : -ENOENT;
 168         if (!ret)
 169                 *snapshot = iter.pos.snapshot;
 170 err:
 171         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
 172                 bch_err(trans->c, "error fetching inode %llu:%u: %s",
 173                         inode_nr, *snapshot, bch2_err_str(ret));
 174         bch2_trans_iter_exit(trans, &iter);
 175         return ret;
 176 }
 177
 178 static int lookup_inode(struct btree_trans *trans, u64 inode_nr,
 179                         struct bch_inode_unpacked *inode,
 180                         u32 *snapshot)
 181 {
 182         return lockrestart_do(trans, __lookup_inode(trans, inode_nr, inode, snapshot));
 183 }
 184
 185 static int __lookup_dirent(struct btree_trans *trans,
 186                            struct bch_hash_info hash_info,
 187                            subvol_inum dir, struct qstr *name,
 188                            u64 *target, unsigned *type)
 189 {
 190         struct btree_iter iter;
 191         struct bkey_s_c_dirent d;
 192         int ret;
 193
 194         ret = bch2_hash_lookup(trans, &iter, bch2_dirent_hash_desc,
 195                                &hash_info, dir, name, 0);
 196         if (ret)
 197                 return ret;
 198
 199         d = bkey_s_c_to_dirent(bch2_btree_iter_peek_slot(&iter));
 200         *target = le64_to_cpu(d.v->d_inum);
 201         *type = d.v->d_type;
 202         bch2_trans_iter_exit(trans, &iter);
 203         return 0;
 204 }
 205
 206 static int __write_inode(struct btree_trans *trans,
 207                          struct bch_inode_unpacked *inode,
 208                          u32 snapshot)
 209 {
 210         struct btree_iter iter;
 211         int ret;
 212
 213         bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes,
 214                             SPOS(0, inode->bi_inum, snapshot),
 215                             BTREE_ITER_INTENT);
 216
 217         ret   = bch2_btree_iter_traverse(&iter) ?:
 218                 bch2_inode_write(trans, &iter, inode);
 219         bch2_trans_iter_exit(trans, &iter);
 220         return ret;
 221 }
 222
 223 static int write_inode(struct btree_trans *trans,
 224                        struct bch_inode_unpacked *inode,
 225                        u32 snapshot)
 226 {
 227         int ret = commit_do(trans, NULL, NULL,
 228                                   BTREE_INSERT_NOFAIL|
 229                                   BTREE_INSERT_LAZY_RW,
 230                                   __write_inode(trans, inode, snapshot));
 231         if (ret)
 232                 bch_err(trans->c, "error in fsck: error updating inode: %s",
 233                         bch2_err_str(ret));
 234         return ret;
 235 }
 236
 237 static int fsck_inode_rm(struct btree_trans *trans, u64 inum, u32 snapshot)
 238 {
 239         struct bch_fs *c = trans->c;
 240         struct btree_iter iter = { NULL };
 241         struct bkey_i_inode_generation delete;
 242         struct bch_inode_unpacked inode_u;
 243         struct bkey_s_c k;
 244         int ret;
 245
 246         do {
 247                 ret   = bch2_btree_delete_range_trans(trans, BTREE_ID_extents,
 248                                                       SPOS(inum, 0, snapshot),
 249                                                       SPOS(inum, U64_MAX, snapshot),
 250                                                       0, NULL) ?:
 251                         bch2_btree_delete_range_trans(trans, BTREE_ID_dirents,
 252                                                       SPOS(inum, 0, snapshot),
 253                                                       SPOS(inum, U64_MAX, snapshot),
 254                                                       0, NULL) ?:
 255                         bch2_btree_delete_range_trans(trans, BTREE_ID_xattrs,
 256                                                       SPOS(inum, 0, snapshot),
 257                                                       SPOS(inum, U64_MAX, snapshot),
 258                                                       0, NULL);
 259         } while (ret == -BCH_ERR_transaction_restart_nested);
 260         if (ret)
 261                 goto err;
 262 retry:
 263         bch2_trans_begin(trans);
 264
 265         bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes,
 266                              SPOS(0, inum, snapshot), BTREE_ITER_INTENT);
 267         k = bch2_btree_iter_peek_slot(&iter);
 268
 269         ret = bkey_err(k);
 270         if (ret)
 271                 goto err;
 272
 273         if (!bkey_is_inode(k.k)) {
 274                 bch2_fs_inconsistent(c,
 275                                      "inode %llu:%u not found when deleting",
 276                                      inum, snapshot);
 277                 ret = -EIO;
 278                 goto err;
 279         }
 280
 281         bch2_inode_unpack(k, &inode_u);
 282
 283         /* Subvolume root? */
 284         if (inode_u.bi_subvol)
 285                 bch_warn(c, "deleting inode %llu marked as unlinked, but also a subvolume root!?", inode_u.bi_inum);
 286
 287         bkey_inode_generation_init(&delete.k_i);
 288         delete.k.p = iter.pos;
 289         delete.v.bi_generation = cpu_to_le32(inode_u.bi_generation + 1);
 290
 291         ret   = bch2_trans_update(trans, &iter, &delete.k_i, 0) ?:
 292                 bch2_trans_commit(trans, NULL, NULL,
 293                                 BTREE_INSERT_NOFAIL);
 294 err:
 295         bch2_trans_iter_exit(trans, &iter);
 296         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 297                 goto retry;
 298
 299         return ret ?: -BCH_ERR_transaction_restart_nested;
 300 }
 301
 302 static int __remove_dirent(struct btree_trans *trans, struct bpos pos)
 303 {
 304         struct bch_fs *c = trans->c;
 305         struct btree_iter iter;
 306         struct bch_inode_unpacked dir_inode;
 307         struct bch_hash_info dir_hash_info;
 308         int ret;
 309
 310         ret = lookup_first_inode(trans, pos.inode, &dir_inode);
 311         if (ret)
 312                 goto err;
 313
 314         dir_hash_info = bch2_hash_info_init(c, &dir_inode);
 315
 316         bch2_trans_iter_init(trans, &iter, BTREE_ID_dirents, pos, BTREE_ITER_INTENT);
 317
 318         ret = bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
 319                                   &dir_hash_info, &iter,
 320                                   BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 321         bch2_trans_iter_exit(trans, &iter);
 322 err:
 323         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
 324                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
 325         return ret;
 326 }
 327
 328 /* Get lost+found, create if it doesn't exist: */
 329 static int lookup_lostfound(struct btree_trans *trans, u32 subvol,
 330                             struct bch_inode_unpacked *lostfound)
 331 {
 332         struct bch_fs *c = trans->c;
 333         struct bch_inode_unpacked root;
 334         struct bch_hash_info root_hash_info;
 335         struct qstr lostfound_str = QSTR("lost+found");
 336         subvol_inum root_inum = { .subvol = subvol };
 337         u64 inum = 0;
 338         unsigned d_type = 0;
 339         u32 snapshot;
 340         int ret;
 341
 342         ret = __subvol_lookup(trans, subvol, &snapshot, &root_inum.inum);
 343         if (ret)
 344                 return ret;
 345
 346         ret = __lookup_inode(trans, root_inum.inum, &root, &snapshot);
 347         if (ret)
 348                 return ret;
 349
 350         root_hash_info = bch2_hash_info_init(c, &root);
 351
 352         ret = __lookup_dirent(trans, root_hash_info, root_inum,
 353                             &lostfound_str, &inum, &d_type);
 354         if (ret == -ENOENT) {
 355                 bch_notice(c, "creating lost+found");
 356                 goto create_lostfound;
 357         }
 358
 359         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
 360                 bch_err(c, "error looking up lost+found: %s", bch2_err_str(ret));
 361         if (ret)
 362                 return ret;
 363
 364         if (d_type != DT_DIR) {
 365                 bch_err(c, "error looking up lost+found: not a directory");
 366                 return ret;
 367         }
 368
 369         /*
 370          * The check_dirents pass has already run, dangling dirents
 371          * shouldn't exist here:
 372          */
 373         return __lookup_inode(trans, inum, lostfound, &snapshot);
 374
 375 create_lostfound:
 376         bch2_inode_init_early(c, lostfound);
 377
 378         ret = bch2_create_trans(trans, root_inum, &root,
 379                                 lostfound, &lostfound_str,
 380                                 0, 0, S_IFDIR|0700, 0, NULL, NULL,
 381                                 (subvol_inum) { }, 0);
 382         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
 383                 bch_err(c, "error creating lost+found: %s", bch2_err_str(ret));
 384         return ret;
 385 }
 386
 387 static int __reattach_inode(struct btree_trans *trans,
 388                           struct bch_inode_unpacked *inode,
 389                           u32 inode_snapshot)
 390 {
 391         struct bch_hash_info dir_hash;
 392         struct bch_inode_unpacked lostfound;
 393         char name_buf[20];
 394         struct qstr name;
 395         u64 dir_offset = 0;
 396         u32 subvol;
 397         int ret;
 398
 399         ret = __snapshot_lookup_subvol(trans, inode_snapshot, &subvol);
 400         if (ret)
 401                 return ret;
 402
 403         ret = lookup_lostfound(trans, subvol, &lostfound);
 404         if (ret)
 405                 return ret;
 406
 407         if (S_ISDIR(inode->bi_mode)) {
 408                 lostfound.bi_nlink++;
 409
 410                 ret = __write_inode(trans, &lostfound, U32_MAX);
 411                 if (ret)
 412                         return ret;
 413         }
 414
 415         dir_hash = bch2_hash_info_init(trans->c, &lostfound);
 416
 417         snprintf(name_buf, sizeof(name_buf), "%llu", inode->bi_inum);
 418         name = (struct qstr) QSTR(name_buf);
 419
 420         ret = bch2_dirent_create(trans,
 421                                  (subvol_inum) {
 422                                         .subvol = subvol,
 423                                         .inum = lostfound.bi_inum,
 424                                  },
 425                                  &dir_hash,
 426                                  inode_d_type(inode),
 427                                  &name, inode->bi_inum, &dir_offset,
 428                                  BCH_HASH_SET_MUST_CREATE);
 429         if (ret)
 430                 return ret;
 431
 432         inode->bi_dir           = lostfound.bi_inum;
 433         inode->bi_dir_offset    = dir_offset;
 434
 435         return __write_inode(trans, inode, inode_snapshot);
 436 }
 437
 438 static int reattach_inode(struct btree_trans *trans,
 439                           struct bch_inode_unpacked *inode,
 440                           u32 inode_snapshot)
 441 {
 442         int ret = commit_do(trans, NULL, NULL,
 443                                   BTREE_INSERT_LAZY_RW|
 444                                   BTREE_INSERT_NOFAIL,
 445                         __reattach_inode(trans, inode, inode_snapshot));
 446         if (ret) {
 447                 bch_err(trans->c, "error reattaching inode %llu: %s",
 448                         inode->bi_inum, bch2_err_str(ret));
 449                 return ret;
 450         }
 451
 452         return ret;
 453 }
 454
 455 static int remove_backpointer(struct btree_trans *trans,
 456                               struct bch_inode_unpacked *inode)
 457 {
 458         struct btree_iter iter;
 459         struct bkey_s_c k;
 460         int ret;
 461
 462         bch2_trans_iter_init(trans, &iter, BTREE_ID_dirents,
 463                              POS(inode->bi_dir, inode->bi_dir_offset), 0);
 464         k = bch2_btree_iter_peek_slot(&iter);
 465         ret = bkey_err(k);
 466         if (ret)
 467                 goto out;
 468         if (k.k->type != KEY_TYPE_dirent) {
 469                 ret = -ENOENT;
 470                 goto out;
 471         }
 472
 473         ret = __remove_dirent(trans, k.k->p);
 474 out:
 475         bch2_trans_iter_exit(trans, &iter);
 476         return ret;
 477 }
 478
 479 struct snapshots_seen_entry {
 480         u32                             id;
 481         u32                             equiv;
 482 };
 483
 484 struct snapshots_seen {
 485         struct bpos                     pos;
 486         DARRAY(struct snapshots_seen_entry) ids;
 487 };
 488
 489 static inline void snapshots_seen_exit(struct snapshots_seen *s)
 490 {
 491         darray_exit(&s->ids);
 492 }
 493
 494 static inline void snapshots_seen_init(struct snapshots_seen *s)
 495 {
 496         memset(s, 0, sizeof(*s));
 497 }
 498
 499 static int snapshots_seen_add(struct bch_fs *c, struct snapshots_seen *s, u32 id)
 500 {
 501         struct snapshots_seen_entry *i, n = { id, id };
 502         int ret;
 503
 504         darray_for_each(s->ids, i) {
 505                 if (n.equiv < i->equiv)
 506                         break;
 507
 508                 if (i->equiv == n.equiv) {
 509                         bch_err(c, "%s(): adding duplicate snapshot", __func__);
 510                         return -EINVAL;
 511                 }
 512         }
 513
 514         ret = darray_insert_item(&s->ids, i - s->ids.data, n);
 515         if (ret)
 516                 bch_err(c, "error reallocating snapshots_seen table (size %zu)",
 517                         s->ids.size);
 518         return ret;
 519 }
 520
 521 static int snapshots_seen_update(struct bch_fs *c, struct snapshots_seen *s,
 522                                  enum btree_id btree_id, struct bpos pos)
 523 {
 524         struct snapshots_seen_entry *i, n = {
 525                 .id     = pos.snapshot,
 526                 .equiv  = bch2_snapshot_equiv(c, pos.snapshot),
 527         };
 528         int ret = 0;
 529
 530         if (bkey_cmp(s->pos, pos))
 531                 s->ids.nr = 0;
 532
 533         pos.snapshot = n.equiv;
 534         s->pos = pos;
 535
 536         darray_for_each(s->ids, i)
 537                 if (i->equiv == n.equiv) {
 538                         if (fsck_err_on(i->id != n.id, c,
 539                                         "snapshot deletion did not run correctly:\n"
 540                                         "  duplicate keys in btree %s at %llu:%llu snapshots %u, %u (equiv %u)\n",
 541                                         bch2_btree_ids[btree_id],
 542                                         pos.inode, pos.offset,
 543                                         i->id, n.id, n.equiv))
 544                                 return -BCH_ERR_need_snapshot_cleanup;
 545
 546                         return 0;
 547                 }
 548
 549         ret = darray_push(&s->ids, n);
 550         if (ret)
 551                 bch_err(c, "error reallocating snapshots_seen table (size %zu)",
 552                         s->ids.size);
 553 fsck_err:
 554         return ret;
 555 }
 556
 557 /**
 558  * key_visible_in_snapshot - returns true if @id is a descendent of @ancestor,
 559  * and @ancestor hasn't been overwritten in @seen
 560  *
 561  * That is, returns whether key in @ancestor snapshot is visible in @id snapshot
 562  */
 563 static bool key_visible_in_snapshot(struct bch_fs *c, struct snapshots_seen *seen,
 564                                     u32 id, u32 ancestor)
 565 {
 566         ssize_t i;
 567         u32 top = seen->ids.nr ? seen->ids.data[seen->ids.nr - 1].equiv : 0;
 568
 569         BUG_ON(id > ancestor);
 570         BUG_ON(!bch2_snapshot_is_equiv(c, id));
 571         BUG_ON(!bch2_snapshot_is_equiv(c, ancestor));
 572
 573         /* @ancestor should be the snapshot most recently added to @seen */
 574         BUG_ON(ancestor != seen->pos.snapshot);
 575         BUG_ON(ancestor != top);
 576
 577         if (id == ancestor)
 578                 return true;
 579
 580         if (!bch2_snapshot_is_ancestor(c, id, ancestor))
 581                 return false;
 582
 583         for (i = seen->ids.nr - 2;
 584              i >= 0 && seen->ids.data[i].equiv >= id;
 585              --i)
 586                 if (bch2_snapshot_is_ancestor(c, id, seen->ids.data[i].equiv) &&
 587                     bch2_snapshot_is_ancestor(c, seen->ids.data[i].equiv, ancestor))
 588                         return false;
 589
 590         return true;
 591 }
 592
 593 /**
 594  * ref_visible - given a key with snapshot id @src that points to a key with
 595  * snapshot id @dst, test whether there is some snapshot in which @dst is
 596  * visible.
 597  *
 598  * This assumes we're visiting @src keys in natural key order.
 599  *
 600  * @s   - list of snapshot IDs already seen at @src
 601  * @src - snapshot ID of src key
 602  * @dst - snapshot ID of dst key
 603  */
 604 static int ref_visible(struct bch_fs *c, struct snapshots_seen *s,
 605                        u32 src, u32 dst)
 606 {
 607         return dst <= src
 608                 ? key_visible_in_snapshot(c, s, dst, src)
 609                 : bch2_snapshot_is_ancestor(c, src, dst);
 610 }
 611
 612 #define for_each_visible_inode(_c, _s, _w, _snapshot, _i)                               \
 613         for (_i = (_w)->inodes.data; _i < (_w)->inodes.data + (_w)->inodes.nr &&        \
 614              (_i)->snapshot <= (_snapshot); _i++)                                       \
 615                 if (key_visible_in_snapshot(_c, _s, _i->snapshot, _snapshot))
 616
 617 struct inode_walker_entry {
 618         struct bch_inode_unpacked inode;
 619         u32                     snapshot;
 620         u64                     count;
 621 };
 622
 623 struct inode_walker {
 624         bool                            first_this_inode;
 625         u64                             cur_inum;
 626
 627         DARRAY(struct inode_walker_entry) inodes;
 628 };
 629
 630 static void inode_walker_exit(struct inode_walker *w)
 631 {
 632         darray_exit(&w->inodes);
 633 }
 634
 635 static struct inode_walker inode_walker_init(void)
 636 {
 637         return (struct inode_walker) { 0, };
 638 }
 639
 640 static int add_inode(struct bch_fs *c, struct inode_walker *w,
 641                      struct bkey_s_c inode)
 642 {
 643         struct bch_inode_unpacked u;
 644
 645         BUG_ON(bch2_inode_unpack(inode, &u));
 646
 647         return darray_push(&w->inodes, ((struct inode_walker_entry) {
 648                 .inode          = u,
 649                 .snapshot       = bch2_snapshot_equiv(c, inode.k->p.snapshot),
 650         }));
 651 }
 652
 653 static int __walk_inode(struct btree_trans *trans,
 654                         struct inode_walker *w, struct bpos pos)
 655 {
 656         struct bch_fs *c = trans->c;
 657         struct btree_iter iter;
 658         struct bkey_s_c k;
 659         u32 restart_count = trans->restart_count;
 660         unsigned i;
 661         int ret;
 662
 663         pos.snapshot = bch2_snapshot_equiv(c, pos.snapshot);
 664
 665         if (pos.inode == w->cur_inum) {
 666                 w->first_this_inode = false;
 667                 goto lookup_snapshot;
 668         }
 669
 670         w->inodes.nr = 0;
 671
 672         for_each_btree_key(trans, iter, BTREE_ID_inodes, POS(0, pos.inode),
 673                            BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
 674                 if (k.k->p.offset != pos.inode)
 675                         break;
 676
 677                 if (bkey_is_inode(k.k))
 678                         add_inode(c, w, k);
 679         }
 680         bch2_trans_iter_exit(trans, &iter);
 681
 682         if (ret)
 683                 return ret;
 684
 685         w->cur_inum             = pos.inode;
 686         w->first_this_inode     = true;
 687
 688         if (trans_was_restarted(trans, restart_count))
 689                 return -BCH_ERR_transaction_restart_nested;
 690
 691 lookup_snapshot:
 692         for (i = 0; i < w->inodes.nr; i++)
 693                 if (bch2_snapshot_is_ancestor(c, pos.snapshot, w->inodes.data[i].snapshot))
 694                         goto found;
 695         return INT_MAX;
 696 found:
 697         BUG_ON(pos.snapshot > w->inodes.data[i].snapshot);
 698
 699         if (pos.snapshot != w->inodes.data[i].snapshot) {
 700                 struct inode_walker_entry e = w->inodes.data[i];
 701
 702                 e.snapshot = pos.snapshot;
 703                 e.count = 0;
 704
 705                 bch_info(c, "have key for inode %llu:%u but have inode in ancestor snapshot %u",
 706                          pos.inode, pos.snapshot, w->inodes.data[i].snapshot);
 707
 708                 while (i && w->inodes.data[i - 1].snapshot > pos.snapshot)
 709                         --i;
 710
 711                 ret = darray_insert_item(&w->inodes, i, e);
 712                 if (ret)
 713                         return ret;
 714         }
 715
 716         return i;
 717 }
 718
 719 static int __get_visible_inodes(struct btree_trans *trans,
 720                                 struct inode_walker *w,
 721                                 struct snapshots_seen *s,
 722                                 u64 inum)
 723 {
 724         struct bch_fs *c = trans->c;
 725         struct btree_iter iter;
 726         struct bkey_s_c k;
 727         int ret;
 728
 729         w->inodes.nr = 0;
 730
 731         for_each_btree_key_norestart(trans, iter, BTREE_ID_inodes, POS(0, inum),
 732                            BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
 733                 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
 734
 735                 if (k.k->p.offset != inum)
 736                         break;
 737
 738                 if (!ref_visible(c, s, s->pos.snapshot, equiv))
 739                         continue;
 740
 741                 if (bkey_is_inode(k.k))
 742                         add_inode(c, w, k);
 743
 744                 if (equiv >= s->pos.snapshot)
 745                         break;
 746         }
 747         bch2_trans_iter_exit(trans, &iter);
 748
 749         return ret;
 750 }
 751
 752 static int check_key_has_snapshot(struct btree_trans *trans,
 753                                   struct btree_iter *iter,
 754                                   struct bkey_s_c k)
 755 {
 756         struct bch_fs *c = trans->c;
 757         struct printbuf buf = PRINTBUF;
 758         int ret = 0;
 759
 760         if (mustfix_fsck_err_on(!bch2_snapshot_equiv(c, k.k->p.snapshot), c,
 761                         "key in missing snapshot: %s",
 762                         (bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
 763                 ret = bch2_btree_delete_at(trans, iter,
 764                                             BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?: 1;
 765 fsck_err:
 766         printbuf_exit(&buf);
 767         return ret;
 768 }
 769
 770 static int hash_redo_key(struct btree_trans *trans,
 771                          const struct bch_hash_desc desc,
 772                          struct bch_hash_info *hash_info,
 773                          struct btree_iter *k_iter, struct bkey_s_c k)
 774 {
 775         struct bkey_i *delete;
 776         struct bkey_i *tmp;
 777
 778         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 779         if (IS_ERR(delete))
 780                 return PTR_ERR(delete);
 781
 782         tmp = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
 783         if (IS_ERR(tmp))
 784                 return PTR_ERR(tmp);
 785
 786         bkey_reassemble(tmp, k);
 787
 788         bkey_init(&delete->k);
 789         delete->k.p = k_iter->pos;
 790         return  bch2_btree_iter_traverse(k_iter) ?:
 791                 bch2_trans_update(trans, k_iter, delete, 0) ?:
 792                 bch2_hash_set_snapshot(trans, desc, hash_info,
 793                                        (subvol_inum) { 0, k.k->p.inode },
 794                                        k.k->p.snapshot, tmp,
 795                                        BCH_HASH_SET_MUST_CREATE,
 796                                        BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
 797                 bch2_trans_commit(trans, NULL, NULL,
 798                                   BTREE_INSERT_NOFAIL|
 799                                   BTREE_INSERT_LAZY_RW);
 800 }
 801
 802 static int hash_check_key(struct btree_trans *trans,
 803                           const struct bch_hash_desc desc,
 804                           struct bch_hash_info *hash_info,
 805                           struct btree_iter *k_iter, struct bkey_s_c hash_k)
 806 {
 807         struct bch_fs *c = trans->c;
 808         struct btree_iter iter = { NULL };
 809         struct printbuf buf = PRINTBUF;
 810         struct bkey_s_c k;
 811         u64 hash;
 812         int ret = 0;
 813
 814         if (hash_k.k->type != desc.key_type)
 815                 return 0;
 816
 817         hash = desc.hash_bkey(hash_info, hash_k);
 818
 819         if (likely(hash == hash_k.k->p.offset))
 820                 return 0;
 821
 822         if (hash_k.k->p.offset < hash)
 823                 goto bad_hash;
 824
 825         for_each_btree_key_norestart(trans, iter, desc.btree_id,
 826                                      POS(hash_k.k->p.inode, hash),
 827                                      BTREE_ITER_SLOTS, k, ret) {
 828                 if (!bkey_cmp(k.k->p, hash_k.k->p))
 829                         break;
 830
 831                 if (fsck_err_on(k.k->type == desc.key_type &&
 832                                 !desc.cmp_bkey(k, hash_k), c,
 833                                 "duplicate hash table keys:\n%s",
 834                                 (printbuf_reset(&buf),
 835                                  bch2_bkey_val_to_text(&buf, c, hash_k),
 836                                  buf.buf))) {
 837                         ret = bch2_hash_delete_at(trans, desc, hash_info, k_iter, 0) ?: 1;
 838                         break;
 839                 }
 840
 841                 if (bkey_deleted(k.k)) {
 842                         bch2_trans_iter_exit(trans, &iter);
 843                         goto bad_hash;
 844                 }
 845         }
 846 out:
 847         bch2_trans_iter_exit(trans, &iter);
 848         printbuf_exit(&buf);
 849         return ret;
 850 bad_hash:
 851         if (fsck_err(c, "hash table key at wrong offset: btree %s inode %llu offset %llu, hashed to %llu\n%s",
 852                      bch2_btree_ids[desc.btree_id], hash_k.k->p.inode, hash_k.k->p.offset, hash,
 853                      (printbuf_reset(&buf),
 854                       bch2_bkey_val_to_text(&buf, c, hash_k), buf.buf))) {
 855                 ret = hash_redo_key(trans, desc, hash_info, k_iter, hash_k);
 856                 if (ret) {
 857                         bch_err(c, "hash_redo_key err %s", bch2_err_str(ret));
 858                         return ret;
 859                 }
 860                 ret = -BCH_ERR_transaction_restart_nested;
 861         }
 862 fsck_err:
 863         goto out;
 864 }
 865
 866 static int check_inode(struct btree_trans *trans,
 867                        struct btree_iter *iter,
 868                        struct bkey_s_c k,
 869                        struct bch_inode_unpacked *prev,
 870                        struct snapshots_seen *s,
 871                        bool full)
 872 {
 873         struct bch_fs *c = trans->c;
 874         struct bch_inode_unpacked u;
 875         bool do_update = false;
 876         int ret;
 877
 878         ret = check_key_has_snapshot(trans, iter, k);
 879         if (ret < 0)
 880                 goto err;
 881         if (ret)
 882                 return 0;
 883
 884         ret = snapshots_seen_update(c, s, iter->btree_id, k.k->p);
 885         if (ret)
 886                 goto err;
 887
 888         /*
 889          * if snapshot id isn't a leaf node, skip it - deletion in
 890          * particular is not atomic, so on the internal snapshot nodes
 891          * we can see inodes marked for deletion after a clean shutdown
 892          */
 893         if (bch2_snapshot_internal_node(c, k.k->p.snapshot))
 894                 return 0;
 895
 896         if (!bkey_is_inode(k.k))
 897                 return 0;
 898
 899         BUG_ON(bch2_inode_unpack(k, &u));
 900
 901         if (!full &&
 902             !(u.bi_flags & (BCH_INODE_I_SIZE_DIRTY|
 903                             BCH_INODE_I_SECTORS_DIRTY|
 904                             BCH_INODE_UNLINKED)))
 905                 return 0;
 906
 907         if (prev->bi_inum != u.bi_inum)
 908                 *prev = u;
 909
 910         if (fsck_err_on(prev->bi_hash_seed      != u.bi_hash_seed ||
 911                         inode_d_type(prev)      != inode_d_type(&u), c,
 912                         "inodes in different snapshots don't match")) {
 913                 bch_err(c, "repair not implemented yet");
 914                 return -EINVAL;
 915         }
 916
 917         if (u.bi_flags & BCH_INODE_UNLINKED &&
 918             (!c->sb.clean ||
 919              fsck_err(c, "filesystem marked clean, but inode %llu unlinked",
 920                       u.bi_inum))) {
 921                 bch2_trans_unlock(trans);
 922                 bch2_fs_lazy_rw(c);
 923
 924                 ret = fsck_inode_rm(trans, u.bi_inum, iter->pos.snapshot);
 925                 if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
 926                         bch_err(c, "error in fsck: error while deleting inode: %s",
 927                                 bch2_err_str(ret));
 928                 return ret;
 929         }
 930
 931         if (u.bi_flags & BCH_INODE_I_SIZE_DIRTY &&
 932             (!c->sb.clean ||
 933              fsck_err(c, "filesystem marked clean, but inode %llu has i_size dirty",
 934                       u.bi_inum))) {
 935                 bch_verbose(c, "truncating inode %llu", u.bi_inum);
 936
 937                 bch2_trans_unlock(trans);
 938                 bch2_fs_lazy_rw(c);
 939
 940                 /*
 941                  * XXX: need to truncate partial blocks too here - or ideally
 942                  * just switch units to bytes and that issue goes away
 943                  */
 944                 ret = bch2_btree_delete_range_trans(trans, BTREE_ID_extents,
 945                                 SPOS(u.bi_inum, round_up(u.bi_size, block_bytes(c)) >> 9,
 946                                      iter->pos.snapshot),
 947                                 POS(u.bi_inum, U64_MAX),
 948                                 0, NULL);
 949                 if (ret) {
 950                         bch_err(c, "error in fsck: error truncating inode: %s",
 951                                 bch2_err_str(ret));
 952                         return ret;
 953                 }
 954
 955                 /*
 956                  * We truncated without our normal sector accounting hook, just
 957                  * make sure we recalculate it:
 958                  */
 959                 u.bi_flags |= BCH_INODE_I_SECTORS_DIRTY;
 960
 961                 u.bi_flags &= ~BCH_INODE_I_SIZE_DIRTY;
 962                 do_update = true;
 963         }
 964
 965         if (u.bi_flags & BCH_INODE_I_SECTORS_DIRTY &&
 966             (!c->sb.clean ||
 967              fsck_err(c, "filesystem marked clean, but inode %llu has i_sectors dirty",
 968                       u.bi_inum))) {
 969                 s64 sectors;
 970
 971                 bch_verbose(c, "recounting sectors for inode %llu",
 972                             u.bi_inum);
 973
 974                 sectors = bch2_count_inode_sectors(trans, u.bi_inum, iter->pos.snapshot);
 975                 if (sectors < 0) {
 976                         bch_err(c, "error in fsck: error recounting inode sectors: %s",
 977                                 bch2_err_str(sectors));
 978                         return sectors;
 979                 }
 980
 981                 u.bi_sectors = sectors;
 982                 u.bi_flags &= ~BCH_INODE_I_SECTORS_DIRTY;
 983                 do_update = true;
 984         }
 985
 986         if (u.bi_flags & BCH_INODE_BACKPTR_UNTRUSTED) {
 987                 u.bi_dir = 0;
 988                 u.bi_dir_offset = 0;
 989                 u.bi_flags &= ~BCH_INODE_BACKPTR_UNTRUSTED;
 990                 do_update = true;
 991         }
 992
 993         if (do_update) {
 994                 ret = __write_inode(trans, &u, iter->pos.snapshot);
 995                 if (ret)
 996                         bch_err(c, "error in fsck: error updating inode: %s",
 997                                 bch2_err_str(ret));
 998         }
 999 err:
1000 fsck_err:
1001         if (ret)
1002                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1003         return ret;
1004 }
1005
1006 noinline_for_stack
1007 static int check_inodes(struct bch_fs *c, bool full)
1008 {
1009         struct btree_trans trans;
1010         struct btree_iter iter;
1011         struct bch_inode_unpacked prev = { 0 };
1012         struct snapshots_seen s;
1013         struct bkey_s_c k;
1014         int ret;
1015
1016         snapshots_seen_init(&s);
1017         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
1018
1019         ret = for_each_btree_key_commit(&trans, iter, BTREE_ID_inodes,
1020                         POS_MIN,
1021                         BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
1022                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
1023                 check_inode(&trans, &iter, k, &prev, &s, full));
1024
1025         bch2_trans_exit(&trans);
1026         snapshots_seen_exit(&s);
1027         if (ret)
1028                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1029         return ret;
1030 }
1031
1032 /*
1033  * Checking for overlapping extents needs to be reimplemented
1034  */
1035 #if 0
1036 static int fix_overlapping_extent(struct btree_trans *trans,
1037                                        struct bkey_s_c k, struct bpos cut_at)
1038 {
1039         struct btree_iter iter;
1040         struct bkey_i *u;
1041         int ret;
1042
1043         u = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
1044         ret = PTR_ERR_OR_ZERO(u);
1045         if (ret)
1046                 return ret;
1047
1048         bkey_reassemble(u, k);
1049         bch2_cut_front(cut_at, u);
1050
1051
1052         /*
1053          * We don't want to go through the extent_handle_overwrites path:
1054          *
1055          * XXX: this is going to screw up disk accounting, extent triggers
1056          * assume things about extent overwrites - we should be running the
1057          * triggers manually here
1058          */
1059         bch2_trans_iter_init(trans, &iter, BTREE_ID_extents, u->k.p,
1060                              BTREE_ITER_INTENT|BTREE_ITER_NOT_EXTENTS);
1061
1062         BUG_ON(iter.flags & BTREE_ITER_IS_EXTENTS);
1063         ret   = bch2_btree_iter_traverse(&iter) ?:
1064                 bch2_trans_update(trans, &iter, u, BTREE_TRIGGER_NORUN) ?:
1065                 bch2_trans_commit(trans, NULL, NULL,
1066                                   BTREE_INSERT_NOFAIL|
1067                                   BTREE_INSERT_LAZY_RW);
1068         bch2_trans_iter_exit(trans, &iter);
1069         return ret;
1070 }
1071 #endif
1072
1073 static struct bkey_s_c_dirent dirent_get_by_pos(struct btree_trans *trans,
1074                                                 struct btree_iter *iter,
1075                                                 struct bpos pos)
1076 {
1077         struct bkey_s_c k;
1078         int ret;
1079
1080         bch2_trans_iter_init(trans, iter, BTREE_ID_dirents, pos, 0);
1081         k = bch2_btree_iter_peek_slot(iter);
1082         ret = bkey_err(k);
1083         if (!ret && k.k->type != KEY_TYPE_dirent)
1084                 ret = -ENOENT;
1085         if (ret) {
1086                 bch2_trans_iter_exit(trans, iter);
1087                 return (struct bkey_s_c_dirent) { .k = ERR_PTR(ret) };
1088         }
1089
1090         return bkey_s_c_to_dirent(k);
1091 }
1092
1093 static bool inode_points_to_dirent(struct bch_inode_unpacked *inode,
1094                                    struct bkey_s_c_dirent d)
1095 {
1096         return  inode->bi_dir           == d.k->p.inode &&
1097                 inode->bi_dir_offset    == d.k->p.offset;
1098 }
1099
1100 static bool dirent_points_to_inode(struct bkey_s_c_dirent d,
1101                                    struct bch_inode_unpacked *inode)
1102 {
1103         return d.v->d_type == DT_SUBVOL
1104                 ? le32_to_cpu(d.v->d_child_subvol)      == inode->bi_subvol
1105                 : le64_to_cpu(d.v->d_inum)              == inode->bi_inum;
1106 }
1107
1108 static int inode_backpointer_exists(struct btree_trans *trans,
1109                                     struct bch_inode_unpacked *inode,
1110                                     u32 snapshot)
1111 {
1112         struct btree_iter iter;
1113         struct bkey_s_c_dirent d;
1114         int ret;
1115
1116         d = dirent_get_by_pos(trans, &iter,
1117                         SPOS(inode->bi_dir, inode->bi_dir_offset, snapshot));
1118         ret = bkey_err(d.s_c);
1119         if (ret)
1120                 return ret == -ENOENT ? 0 : ret;
1121
1122         ret = dirent_points_to_inode(d, inode);
1123         bch2_trans_iter_exit(trans, &iter);
1124         return ret;
1125 }
1126
1127 static int check_i_sectors(struct btree_trans *trans, struct inode_walker *w)
1128 {
1129         struct bch_fs *c = trans->c;
1130         struct inode_walker_entry *i;
1131         u32 restart_count = trans->restart_count;
1132         int ret = 0;
1133         s64 count2;
1134
1135         darray_for_each(w->inodes, i) {
1136                 if (i->inode.bi_sectors == i->count)
1137                         continue;
1138
1139                 count2 = bch2_count_inode_sectors(trans, w->cur_inum, i->snapshot);
1140
1141                 if (i->count != count2) {
1142                         bch_err(c, "fsck counted i_sectors wrong: got %llu should be %llu",
1143                                 i->count, count2);
1144                         i->count = count2;
1145                         if (i->inode.bi_sectors == i->count)
1146                                 continue;
1147                 }
1148
1149                 if (fsck_err_on(!(i->inode.bi_flags & BCH_INODE_I_SECTORS_DIRTY), c,
1150                             "inode %llu:%u has incorrect i_sectors: got %llu, should be %llu",
1151                             w->cur_inum, i->snapshot,
1152                             i->inode.bi_sectors, i->count)) {
1153                         i->inode.bi_sectors = i->count;
1154                         ret = write_inode(trans, &i->inode, i->snapshot);
1155                         if (ret)
1156                                 break;
1157                 }
1158         }
1159 fsck_err:
1160         if (ret)
1161                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1162         if (!ret && trans_was_restarted(trans, restart_count))
1163                 ret = -BCH_ERR_transaction_restart_nested;
1164         return ret;
1165 }
1166
1167 static int check_extent(struct btree_trans *trans, struct btree_iter *iter,
1168                         struct bkey_s_c k,
1169                         struct inode_walker *inode,
1170                         struct snapshots_seen *s)
1171 {
1172         struct bch_fs *c = trans->c;
1173         struct inode_walker_entry *i;
1174         struct printbuf buf = PRINTBUF;
1175         struct bpos equiv;
1176         int ret = 0;
1177
1178         ret = check_key_has_snapshot(trans, iter, k);
1179         if (ret) {
1180                 ret = ret < 0 ? ret : 0;
1181                 goto out;
1182         }
1183
1184         equiv = k.k->p;
1185         equiv.snapshot = bch2_snapshot_equiv(c, k.k->p.snapshot);
1186
1187         ret = snapshots_seen_update(c, s, iter->btree_id, k.k->p);
1188         if (ret)
1189                 goto err;
1190
1191         if (k.k->type == KEY_TYPE_whiteout)
1192                 goto out;
1193
1194         if (inode->cur_inum != k.k->p.inode) {
1195                 ret = check_i_sectors(trans, inode);
1196                 if (ret)
1197                         goto err;
1198         }
1199
1200         BUG_ON(!iter->path->should_be_locked);
1201 #if 0
1202         if (bkey_cmp(prev.k->k.p, bkey_start_pos(k.k)) > 0) {
1203                 char buf1[200];
1204                 char buf2[200];
1205
1206                 bch2_bkey_val_to_text(&PBUF(buf1), c, bkey_i_to_s_c(prev.k));
1207                 bch2_bkey_val_to_text(&PBUF(buf2), c, k);
1208
1209                 if (fsck_err(c, "overlapping extents:\n%s\n%s", buf1, buf2)) {
1210                         ret = fix_overlapping_extent(trans, k, prev.k->k.p)
1211                                 ?: -BCH_ERR_transaction_restart_nested;
1212                         goto out;
1213                 }
1214         }
1215 #endif
1216         ret = __walk_inode(trans, inode, equiv);
1217         if (ret < 0)
1218                 goto err;
1219
1220         if (fsck_err_on(ret == INT_MAX, c,
1221                         "extent in missing inode:\n  %s",
1222                         (printbuf_reset(&buf),
1223                          bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
1224                 ret = bch2_btree_delete_at(trans, iter,
1225                                             BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
1226                 goto out;
1227         }
1228
1229         if (ret == INT_MAX) {
1230                 ret = 0;
1231                 goto out;
1232         }
1233
1234         i = inode->inodes.data + ret;
1235         ret = 0;
1236
1237         if (fsck_err_on(!S_ISREG(i->inode.bi_mode) &&
1238                         !S_ISLNK(i->inode.bi_mode), c,
1239                         "extent in non regular inode mode %o:\n  %s",
1240                         i->inode.bi_mode,
1241                         (printbuf_reset(&buf),
1242                          bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
1243                 ret = bch2_btree_delete_at(trans, iter,
1244                                             BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
1245                 goto out;
1246         }
1247
1248         /*
1249          * Check inodes in reverse order, from oldest snapshots to newest, so
1250          * that we emit the fewest number of whiteouts necessary:
1251          */
1252         for (i = inode->inodes.data + inode->inodes.nr - 1;
1253              i >= inode->inodes.data;
1254              --i) {
1255                 if (i->snapshot > equiv.snapshot ||
1256                     !key_visible_in_snapshot(c, s, i->snapshot, equiv.snapshot))
1257                         continue;
1258
1259                 if (fsck_err_on(!(i->inode.bi_flags & BCH_INODE_I_SIZE_DIRTY) &&
1260                                 k.k->type != KEY_TYPE_reservation &&
1261                                 k.k->p.offset > round_up(i->inode.bi_size, block_bytes(c)) >> 9, c,
1262                                 "extent type past end of inode %llu:%u, i_size %llu\n  %s",
1263                                 i->inode.bi_inum, i->snapshot, i->inode.bi_size,
1264                                 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
1265                         struct btree_iter iter2;
1266
1267                         bch2_trans_copy_iter(&iter2, iter);
1268                         bch2_btree_iter_set_snapshot(&iter2, i->snapshot);
1269                         ret =   bch2_btree_iter_traverse(&iter2) ?:
1270                                 bch2_btree_delete_at(trans, &iter2,
1271                                         BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
1272                         bch2_trans_iter_exit(trans, &iter2);
1273                         if (ret)
1274                                 goto err;
1275
1276                         if (i->snapshot != equiv.snapshot) {
1277                                 ret = snapshots_seen_add(c, s, i->snapshot);
1278                                 if (ret)
1279                                         goto err;
1280                         }
1281                 }
1282         }
1283
1284         if (bkey_extent_is_allocation(k.k))
1285                 for_each_visible_inode(c, s, inode, equiv.snapshot, i)
1286                         i->count += k.k->size;
1287 #if 0
1288         bch2_bkey_buf_reassemble(&prev, c, k);
1289 #endif
1290
1291 out:
1292 err:
1293 fsck_err:
1294         printbuf_exit(&buf);
1295
1296         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
1297                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1298         return ret;
1299 }
1300
1301 /*
1302  * Walk extents: verify that extents have a corresponding S_ISREG inode, and
1303  * that i_size an i_sectors are consistent
1304  */
1305 noinline_for_stack
1306 static int check_extents(struct bch_fs *c)
1307 {
1308         struct inode_walker w = inode_walker_init();
1309         struct snapshots_seen s;
1310         struct btree_trans trans;
1311         struct btree_iter iter;
1312         struct bkey_s_c k;
1313         int ret = 0;
1314
1315 #if 0
1316         struct bkey_buf prev;
1317         bch2_bkey_buf_init(&prev);
1318         prev.k->k = KEY(0, 0, 0);
1319 #endif
1320         snapshots_seen_init(&s);
1321         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
1322
1323         bch_verbose(c, "checking extents");
1324
1325         ret = for_each_btree_key_commit(&trans, iter, BTREE_ID_extents,
1326                         POS(BCACHEFS_ROOT_INO, 0),
1327                         BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
1328                         NULL, NULL,
1329                         BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
1330                 check_extent(&trans, &iter, k, &w, &s));
1331 #if 0
1332         bch2_bkey_buf_exit(&prev, c);
1333 #endif
1334         inode_walker_exit(&w);
1335         bch2_trans_exit(&trans);
1336         snapshots_seen_exit(&s);
1337
1338         if (ret)
1339                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1340         return ret;
1341 }
1342
1343 static int check_subdir_count(struct btree_trans *trans, struct inode_walker *w)
1344 {
1345         struct bch_fs *c = trans->c;
1346         struct inode_walker_entry *i;
1347         u32 restart_count = trans->restart_count;
1348         int ret = 0;
1349         s64 count2;
1350
1351         darray_for_each(w->inodes, i) {
1352                 if (i->inode.bi_nlink == i->count)
1353                         continue;
1354
1355                 count2 = bch2_count_subdirs(trans, w->cur_inum, i->snapshot);
1356                 if (count2 < 0)
1357                         return count2;
1358
1359                 if (i->count != count2) {
1360                         bch_err(c, "fsck counted subdirectories wrong: got %llu should be %llu",
1361                                 i->count, count2);
1362                         i->count = count2;
1363                         if (i->inode.bi_nlink == i->count)
1364                                 continue;
1365                 }
1366
1367                 if (fsck_err_on(i->inode.bi_nlink != i->count, c,
1368                                 "directory %llu:%u with wrong i_nlink: got %u, should be %llu",
1369                                 w->cur_inum, i->snapshot, i->inode.bi_nlink, i->count)) {
1370                         i->inode.bi_nlink = i->count;
1371                         ret = write_inode(trans, &i->inode, i->snapshot);
1372                         if (ret)
1373                                 break;
1374                 }
1375         }
1376 fsck_err:
1377         if (ret)
1378                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1379         if (!ret && trans_was_restarted(trans, restart_count))
1380                 ret = -BCH_ERR_transaction_restart_nested;
1381         return ret;
1382 }
1383
1384 static int check_dirent_target(struct btree_trans *trans,
1385                                struct btree_iter *iter,
1386                                struct bkey_s_c_dirent d,
1387                                struct bch_inode_unpacked *target,
1388                                u32 target_snapshot)
1389 {
1390         struct bch_fs *c = trans->c;
1391         struct bkey_i_dirent *n;
1392         bool backpointer_exists = true;
1393         struct printbuf buf = PRINTBUF;
1394         int ret = 0;
1395
1396         if (!target->bi_dir &&
1397             !target->bi_dir_offset) {
1398                 target->bi_dir          = d.k->p.inode;
1399                 target->bi_dir_offset   = d.k->p.offset;
1400
1401                 ret = __write_inode(trans, target, target_snapshot);
1402                 if (ret)
1403                         goto err;
1404         }
1405
1406         if (!inode_points_to_dirent(target, d)) {
1407                 ret = inode_backpointer_exists(trans, target, d.k->p.snapshot);
1408                 if (ret < 0)
1409                         goto err;
1410
1411                 backpointer_exists = ret;
1412                 ret = 0;
1413
1414                 if (fsck_err_on(S_ISDIR(target->bi_mode) &&
1415                                 backpointer_exists, c,
1416                                 "directory %llu with multiple links",
1417                                 target->bi_inum)) {
1418                         ret = __remove_dirent(trans, d.k->p);
1419                         goto out;
1420                 }
1421
1422                 if (fsck_err_on(backpointer_exists &&
1423                                 !target->bi_nlink, c,
1424                                 "inode %llu type %s has multiple links but i_nlink 0",
1425                                 target->bi_inum, bch2_d_types[d.v->d_type])) {
1426                         target->bi_nlink++;
1427                         target->bi_flags &= ~BCH_INODE_UNLINKED;
1428
1429                         ret = __write_inode(trans, target, target_snapshot);
1430                         if (ret)
1431                                 goto err;
1432                 }
1433
1434                 if (fsck_err_on(!backpointer_exists, c,
1435                                 "inode %llu:%u has wrong backpointer:\n"
1436                                 "got       %llu:%llu\n"
1437                                 "should be %llu:%llu",
1438                                 target->bi_inum, target_snapshot,
1439                                 target->bi_dir,
1440                                 target->bi_dir_offset,
1441                                 d.k->p.inode,
1442                                 d.k->p.offset)) {
1443                         target->bi_dir          = d.k->p.inode;
1444                         target->bi_dir_offset   = d.k->p.offset;
1445
1446                         ret = __write_inode(trans, target, target_snapshot);
1447                         if (ret)
1448                                 goto err;
1449                 }
1450         }
1451
1452         if (fsck_err_on(d.v->d_type != inode_d_type(target), c,
1453                         "incorrect d_type: got %s, should be %s:\n%s",
1454                         bch2_d_type_str(d.v->d_type),
1455                         bch2_d_type_str(inode_d_type(target)),
1456                         (printbuf_reset(&buf),
1457                          bch2_bkey_val_to_text(&buf, c, d.s_c), buf.buf))) {
1458                 n = bch2_trans_kmalloc(trans, bkey_bytes(d.k));
1459                 ret = PTR_ERR_OR_ZERO(n);
1460                 if (ret)
1461                         goto err;
1462
1463                 bkey_reassemble(&n->k_i, d.s_c);
1464                 n->v.d_type = inode_d_type(target);
1465
1466                 ret = bch2_trans_update(trans, iter, &n->k_i, 0);
1467                 if (ret)
1468                         goto err;
1469
1470                 d = dirent_i_to_s_c(n);
1471         }
1472
1473         if (d.v->d_type == DT_SUBVOL &&
1474             target->bi_parent_subvol != le32_to_cpu(d.v->d_parent_subvol) &&
1475             (c->sb.version < bcachefs_metadata_version_subvol_dirent ||
1476              fsck_err(c, "dirent has wrong d_parent_subvol field: got %u, should be %u",
1477                       le32_to_cpu(d.v->d_parent_subvol),
1478                       target->bi_parent_subvol))) {
1479                 n = bch2_trans_kmalloc(trans, bkey_bytes(d.k));
1480                 ret = PTR_ERR_OR_ZERO(n);
1481                 if (ret)
1482                         goto err;
1483
1484                 bkey_reassemble(&n->k_i, d.s_c);
1485                 n->v.d_parent_subvol = cpu_to_le32(target->bi_parent_subvol);
1486
1487                 ret = bch2_trans_update(trans, iter, &n->k_i, 0);
1488                 if (ret)
1489                         goto err;
1490
1491                 d = dirent_i_to_s_c(n);
1492         }
1493 out:
1494 err:
1495 fsck_err:
1496         printbuf_exit(&buf);
1497
1498         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
1499                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1500         return ret;
1501 }
1502
1503 static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
1504                         struct bkey_s_c k,
1505                         struct bch_hash_info *hash_info,
1506                         struct inode_walker *dir,
1507                         struct inode_walker *target,
1508                         struct snapshots_seen *s)
1509 {
1510         struct bch_fs *c = trans->c;
1511         struct bkey_s_c_dirent d;
1512         struct inode_walker_entry *i;
1513         struct printbuf buf = PRINTBUF;
1514         struct bpos equiv;
1515         int ret = 0;
1516
1517         ret = check_key_has_snapshot(trans, iter, k);
1518         if (ret) {
1519                 ret = ret < 0 ? ret : 0;
1520                 goto out;
1521         }
1522
1523         equiv = k.k->p;
1524         equiv.snapshot = bch2_snapshot_equiv(c, k.k->p.snapshot);
1525
1526         ret = snapshots_seen_update(c, s, iter->btree_id, k.k->p);
1527         if (ret)
1528                 goto err;
1529
1530         if (k.k->type == KEY_TYPE_whiteout)
1531                 goto out;
1532
1533         if (dir->cur_inum != k.k->p.inode) {
1534                 ret = check_subdir_count(trans, dir);
1535                 if (ret)
1536                         goto err;
1537         }
1538
1539         BUG_ON(!iter->path->should_be_locked);
1540
1541         ret = __walk_inode(trans, dir, equiv);
1542         if (ret < 0)
1543                 goto err;
1544
1545         if (fsck_err_on(ret == INT_MAX, c,
1546                         "dirent in nonexisting directory:\n%s",
1547                         (printbuf_reset(&buf),
1548                          bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
1549                 ret = bch2_btree_delete_at(trans, iter,
1550                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
1551                 goto out;
1552         }
1553
1554         if (ret == INT_MAX) {
1555                 ret = 0;
1556                 goto out;
1557         }
1558
1559         i = dir->inodes.data + ret;
1560         ret = 0;
1561
1562         if (fsck_err_on(!S_ISDIR(i->inode.bi_mode), c,
1563                         "dirent in non directory inode type %s:\n%s",
1564                         bch2_d_type_str(inode_d_type(&i->inode)),
1565                         (printbuf_reset(&buf),
1566                          bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
1567                 ret = bch2_btree_delete_at(trans, iter, 0);
1568                 goto out;
1569         }
1570
1571         if (dir->first_this_inode)
1572                 *hash_info = bch2_hash_info_init(c, &dir->inodes.data[0].inode);
1573
1574         ret = hash_check_key(trans, bch2_dirent_hash_desc,
1575                              hash_info, iter, k);
1576         if (ret < 0)
1577                 goto err;
1578         if (ret) {
1579                 /* dirent has been deleted */
1580                 ret = 0;
1581                 goto out;
1582         }
1583
1584         if (k.k->type != KEY_TYPE_dirent)
1585                 goto out;
1586
1587         d = bkey_s_c_to_dirent(k);
1588
1589         if (d.v->d_type == DT_SUBVOL) {
1590                 struct bch_inode_unpacked subvol_root;
1591                 u32 target_subvol = le32_to_cpu(d.v->d_child_subvol);
1592                 u32 target_snapshot;
1593                 u64 target_inum;
1594
1595                 ret = __subvol_lookup(trans, target_subvol,
1596                                       &target_snapshot, &target_inum);
1597                 if (ret && ret != -ENOENT)
1598                         goto err;
1599
1600                 if (fsck_err_on(ret, c,
1601                                 "dirent points to missing subvolume %llu",
1602                                 le64_to_cpu(d.v->d_child_subvol))) {
1603                         ret = __remove_dirent(trans, d.k->p);
1604                         goto err;
1605                 }
1606
1607                 ret = __lookup_inode(trans, target_inum,
1608                                    &subvol_root, &target_snapshot);
1609                 if (ret && ret != -ENOENT)
1610                         goto err;
1611
1612                 if (fsck_err_on(ret, c,
1613                                 "subvolume %u points to missing subvolume root %llu",
1614                                 target_subvol,
1615                                 target_inum)) {
1616                         bch_err(c, "repair not implemented yet");
1617                         ret = -EINVAL;
1618                         goto err;
1619                 }
1620
1621                 if (fsck_err_on(subvol_root.bi_subvol != target_subvol, c,
1622                                 "subvol root %llu has wrong bi_subvol field: got %u, should be %u",
1623                                 target_inum,
1624                                 subvol_root.bi_subvol, target_subvol)) {
1625                         subvol_root.bi_subvol = target_subvol;
1626                         ret = __write_inode(trans, &subvol_root, target_snapshot);
1627                         if (ret)
1628                                 goto err;
1629                 }
1630
1631                 ret = check_dirent_target(trans, iter, d, &subvol_root,
1632                                           target_snapshot);
1633                 if (ret)
1634                         goto err;
1635         } else {
1636                 ret = __get_visible_inodes(trans, target, s, le64_to_cpu(d.v->d_inum));
1637                 if (ret)
1638                         goto err;
1639
1640                 if (fsck_err_on(!target->inodes.nr, c,
1641                                 "dirent points to missing inode: (equiv %u)\n%s",
1642                                 equiv.snapshot,
1643                                 (printbuf_reset(&buf),
1644                                  bch2_bkey_val_to_text(&buf, c, k),
1645                                  buf.buf))) {
1646                         ret = __remove_dirent(trans, d.k->p);
1647                         if (ret)
1648                                 goto err;
1649                 }
1650
1651                 darray_for_each(target->inodes, i) {
1652                         ret = check_dirent_target(trans, iter, d,
1653                                                   &i->inode, i->snapshot);
1654                         if (ret)
1655                                 goto err;
1656                 }
1657         }
1658
1659         if (d.v->d_type == DT_DIR)
1660                 for_each_visible_inode(c, s, dir, equiv.snapshot, i)
1661                         i->count++;
1662
1663 out:
1664 err:
1665 fsck_err:
1666         printbuf_exit(&buf);
1667
1668         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
1669                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1670         return ret;
1671 }
1672
1673 /*
1674  * Walk dirents: verify that they all have a corresponding S_ISDIR inode,
1675  * validate d_type
1676  */
1677 noinline_for_stack
1678 static int check_dirents(struct bch_fs *c)
1679 {
1680         struct inode_walker dir = inode_walker_init();
1681         struct inode_walker target = inode_walker_init();
1682         struct snapshots_seen s;
1683         struct bch_hash_info hash_info;
1684         struct btree_trans trans;
1685         struct btree_iter iter;
1686         struct bkey_s_c k;
1687         int ret = 0;
1688
1689         bch_verbose(c, "checking dirents");
1690
1691         snapshots_seen_init(&s);
1692         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
1693
1694         ret = for_each_btree_key_commit(&trans, iter, BTREE_ID_dirents,
1695                         POS(BCACHEFS_ROOT_INO, 0),
1696                         BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS,
1697                         k,
1698                         NULL, NULL,
1699                         BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
1700                 check_dirent(&trans, &iter, k, &hash_info, &dir, &target, &s));
1701
1702         bch2_trans_exit(&trans);
1703         snapshots_seen_exit(&s);
1704         inode_walker_exit(&dir);
1705         inode_walker_exit(&target);
1706
1707         if (ret)
1708                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1709         return ret;
1710 }
1711
1712 static int check_xattr(struct btree_trans *trans, struct btree_iter *iter,
1713                        struct bkey_s_c k,
1714                        struct bch_hash_info *hash_info,
1715                        struct inode_walker *inode)
1716 {
1717         struct bch_fs *c = trans->c;
1718         int ret;
1719
1720         ret = check_key_has_snapshot(trans, iter, k);
1721         if (ret)
1722                 return ret;
1723
1724         ret = __walk_inode(trans, inode, k.k->p);
1725         if (ret < 0)
1726                 return ret;
1727
1728         if (fsck_err_on(ret == INT_MAX, c,
1729                         "xattr for missing inode %llu",
1730                         k.k->p.inode))
1731                 return bch2_btree_delete_at(trans, iter, 0);
1732
1733         if (ret == INT_MAX)
1734                 return 0;
1735
1736         ret = 0;
1737
1738         if (inode->first_this_inode)
1739                 *hash_info = bch2_hash_info_init(c, &inode->inodes.data[0].inode);
1740
1741         ret = hash_check_key(trans, bch2_xattr_hash_desc, hash_info, iter, k);
1742 fsck_err:
1743         if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
1744                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1745         return ret;
1746 }
1747
1748 /*
1749  * Walk xattrs: verify that they all have a corresponding inode
1750  */
1751 noinline_for_stack
1752 static int check_xattrs(struct bch_fs *c)
1753 {
1754         struct inode_walker inode = inode_walker_init();
1755         struct bch_hash_info hash_info;
1756         struct btree_trans trans;
1757         struct btree_iter iter;
1758         struct bkey_s_c k;
1759         int ret = 0;
1760
1761         bch_verbose(c, "checking xattrs");
1762
1763         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
1764
1765         ret = for_each_btree_key_commit(&trans, iter, BTREE_ID_xattrs,
1766                         POS(BCACHEFS_ROOT_INO, 0),
1767                         BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS,
1768                         k,
1769                         NULL, NULL,
1770                         BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
1771                 check_xattr(&trans, &iter, k, &hash_info, &inode));
1772
1773         bch2_trans_exit(&trans);
1774
1775         if (ret)
1776                 bch_err(c, "%s(): error %s", __func__, bch2_err_str(ret));
1777         return ret;
1778 }
1779
1780 static int check_root_trans(struct btree_trans *trans)
1781 {
1782         struct bch_fs *c = trans->c;
1783         struct bch_inode_unpacked root_inode;
1784         u32 snapshot;
1785         u64 inum;
1786         int ret;
1787
1788         ret = __subvol_lookup(trans, BCACHEFS_ROOT_SUBVOL, &snapshot, &inum);
1789         if (ret && ret != -ENOENT)
1790                 return ret;
1791
1792         if (mustfix_fsck_err_on(ret, c, "root subvol missing")) {
1793                 struct bkey_i_subvolume root_subvol;
1794
1795                 snapshot        = U32_MAX;
1796                 inum            = BCACHEFS_ROOT_INO;
1797
1798                 bkey_subvolume_init(&root_subvol.k_i);
1799                 root_subvol.k.p.offset = BCACHEFS_ROOT_SUBVOL;
1800                 root_subvol.v.flags     = 0;
1801                 root_subvol.v.snapshot  = cpu_to_le32(snapshot);
1802                 root_subvol.v.inode     = cpu_to_le64(inum);
1803                 ret = commit_do(trans, NULL, NULL,
1804                                       BTREE_INSERT_NOFAIL|
1805                                       BTREE_INSERT_LAZY_RW,
1806                         __bch2_btree_insert(trans, BTREE_ID_subvolumes, &root_subvol.k_i));
1807                 if (ret) {
1808                         bch_err(c, "error writing root subvol: %s", bch2_err_str(ret));
1809                         goto err;
1810                 }
1811
1812         }
1813
1814         ret = __lookup_inode(trans, BCACHEFS_ROOT_INO, &root_inode, &snapshot);
1815         if (ret && ret != -ENOENT)
1816                 return ret;
1817
1818         if (mustfix_fsck_err_on(ret, c, "root directory missing") ||
1819             mustfix_fsck_err_on(!S_ISDIR(root_inode.bi_mode), c,
1820                                 "root inode not a directory")) {
1821                 bch2_inode_init(c, &root_inode, 0, 0, S_IFDIR|0755,
1822                                 0, NULL);
1823                 root_inode.bi_inum = inum;
1824
1825                 ret = __write_inode(trans, &root_inode, snapshot);
1826                 if (ret)
1827                         bch_err(c, "error writing root inode: %s", bch2_err_str(ret));
1828         }
1829 err:
1830 fsck_err:
1831         return ret;
1832 }
1833
1834 /* Get root directory, create if it doesn't exist: */
1835 noinline_for_stack
1836 static int check_root(struct bch_fs *c)
1837 {
1838         bch_verbose(c, "checking root directory");
1839
1840         return bch2_trans_do(c, NULL, NULL,
1841                              BTREE_INSERT_NOFAIL|
1842                              BTREE_INSERT_LAZY_RW,
1843                 check_root_trans(&trans));
1844 }
1845
1846 struct pathbuf_entry {
1847         u64     inum;
1848         u32     snapshot;
1849 };
1850
1851 typedef DARRAY(struct pathbuf_entry) pathbuf;
1852
1853 static bool path_is_dup(pathbuf *p, u64 inum, u32 snapshot)
1854 {
1855         struct pathbuf_entry *i;
1856
1857         darray_for_each(*p, i)
1858                 if (i->inum     == inum &&
1859                     i->snapshot == snapshot)
1860                         return true;
1861
1862         return false;
1863 }
1864
1865 static int path_down(struct bch_fs *c, pathbuf *p,
1866                      u64 inum, u32 snapshot)
1867 {
1868         int ret = darray_push(p, ((struct pathbuf_entry) {
1869                 .inum           = inum,
1870                 .snapshot       = snapshot,
1871         }));
1872
1873         if (ret)
1874                 bch_err(c, "fsck: error allocating memory for pathbuf, size %zu",
1875                         p->size);
1876         return ret;
1877 }
1878
1879 /*
1880  * Check that a given inode is reachable from the root:
1881  *
1882  * XXX: we should also be verifying that inodes are in the right subvolumes
1883  */
1884 static int check_path(struct btree_trans *trans,
1885                       pathbuf *p,
1886                       struct bch_inode_unpacked *inode,
1887                       u32 snapshot)
1888 {
1889         struct bch_fs *c = trans->c;
1890         int ret = 0;
1891
1892         snapshot = bch2_snapshot_equiv(c, snapshot);
1893         p->nr = 0;
1894
1895         while (!(inode->bi_inum == BCACHEFS_ROOT_INO &&
1896                  inode->bi_subvol == BCACHEFS_ROOT_SUBVOL)) {
1897                 struct btree_iter dirent_iter;
1898                 struct bkey_s_c_dirent d;
1899                 u32 parent_snapshot = snapshot;
1900
1901                 if (inode->bi_subvol) {
1902                         u64 inum;
1903
1904                         ret = subvol_lookup(trans, inode->bi_parent_subvol,
1905                                             &parent_snapshot, &inum);
1906                         if (ret)
1907                                 break;
1908                 }
1909
1910                 ret = lockrestart_do(trans,
1911                         PTR_ERR_OR_ZERO((d = dirent_get_by_pos(trans, &dirent_iter,
1912                                           SPOS(inode->bi_dir, inode->bi_dir_offset,
1913                                                parent_snapshot))).k));
1914                 if (ret && ret != -ENOENT)
1915                         break;
1916
1917                 if (!ret && !dirent_points_to_inode(d, inode)) {
1918                         bch2_trans_iter_exit(trans, &dirent_iter);
1919                         ret = -ENOENT;
1920                 }
1921
1922                 if (ret == -ENOENT) {
1923                         if (fsck_err(c,  "unreachable inode %llu:%u, type %s nlink %u backptr %llu:%llu",
1924                                      inode->bi_inum, snapshot,
1925                                      bch2_d_type_str(inode_d_type(inode)),
1926                                      inode->bi_nlink,
1927                                      inode->bi_dir,
1928                                      inode->bi_dir_offset))
1929                                 ret = reattach_inode(trans, inode, snapshot);
1930                         break;
1931                 }
1932
1933                 bch2_trans_iter_exit(trans, &dirent_iter);
1934
1935                 if (!S_ISDIR(inode->bi_mode))
1936                         break;
1937
1938                 ret = path_down(c, p, inode->bi_inum, snapshot);
1939                 if (ret) {
1940                         bch_err(c, "memory allocation failure");
1941                         return ret;
1942                 }
1943
1944                 snapshot = parent_snapshot;
1945
1946                 ret = lookup_inode(trans, inode->bi_dir, inode, &snapshot);
1947                 if (ret) {
1948                         /* Should have been caught in dirents pass */
1949                         bch_err(c, "error looking up parent directory: %i", ret);
1950                         break;
1951                 }
1952
1953                 if (path_is_dup(p, inode->bi_inum, snapshot)) {
1954                         struct pathbuf_entry *i;
1955
1956                         /* XXX print path */
1957                         bch_err(c, "directory structure loop");
1958
1959                         darray_for_each(*p, i)
1960                                 pr_err("%llu:%u", i->inum, i->snapshot);
1961                         pr_err("%llu:%u", inode->bi_inum, snapshot);
1962
1963                         if (!fsck_err(c, "directory structure loop"))
1964                                 return 0;
1965
1966                         ret = commit_do(trans, NULL, NULL,
1967                                               BTREE_INSERT_NOFAIL|
1968                                               BTREE_INSERT_LAZY_RW,
1969                                         remove_backpointer(trans, inode));
1970                         if (ret) {
1971                                 bch_err(c, "error removing dirent: %i", ret);
1972                                 break;
1973                         }
1974
1975                         ret = reattach_inode(trans, inode, snapshot);
1976                 }
1977         }
1978 fsck_err:
1979         if (ret)
1980                 bch_err(c, "%s: err %s", __func__, bch2_err_str(ret));
1981         return ret;
1982 }
1983
1984 /*
1985  * Check for unreachable inodes, as well as loops in the directory structure:
1986  * After check_dirents(), if an inode backpointer doesn't exist that means it's
1987  * unreachable:
1988  */
1989 noinline_for_stack
1990 static int check_directory_structure(struct bch_fs *c)
1991 {
1992         struct btree_trans trans;
1993         struct btree_iter iter;
1994         struct bkey_s_c k;
1995         struct bch_inode_unpacked u;
1996         pathbuf path = { 0, };
1997         int ret;
1998
1999         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
2000
2001         for_each_btree_key(&trans, iter, BTREE_ID_inodes, POS_MIN,
2002                            BTREE_ITER_INTENT|
2003                            BTREE_ITER_PREFETCH|
2004                            BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
2005                 if (!bkey_is_inode(k.k))
2006                         continue;
2007
2008                 ret = bch2_inode_unpack(k, &u);
2009                 if (ret) {
2010                         /* Should have been caught earlier in fsck: */
2011                         bch_err(c, "error unpacking inode %llu: %i", k.k->p.offset, ret);
2012                         break;
2013                 }
2014
2015                 if (u.bi_flags & BCH_INODE_UNLINKED)
2016                         continue;
2017
2018                 ret = check_path(&trans, &path, &u, iter.pos.snapshot);
2019                 if (ret)
2020                         break;
2021         }
2022         bch2_trans_iter_exit(&trans, &iter);
2023
2024         darray_exit(&path);
2025
2026         bch2_trans_exit(&trans);
2027         return ret;
2028 }
2029
2030 struct nlink_table {
2031         size_t          nr;
2032         size_t          size;
2033
2034         struct nlink {
2035                 u64     inum;
2036                 u32     snapshot;
2037                 u32     count;
2038         }               *d;
2039 };
2040
2041 static int add_nlink(struct bch_fs *c, struct nlink_table *t,
2042                      u64 inum, u32 snapshot)
2043 {
2044         if (t->nr == t->size) {
2045                 size_t new_size = max_t(size_t, 128UL, t->size * 2);
2046                 void *d = kvmalloc_array(new_size, sizeof(t->d[0]), GFP_KERNEL);
2047
2048                 if (!d) {
2049                         bch_err(c, "fsck: error allocating memory for nlink_table, size %zu",
2050                                 new_size);
2051                         return -ENOMEM;
2052                 }
2053
2054                 if (t->d)
2055                         memcpy(d, t->d, t->size * sizeof(t->d[0]));
2056                 kvfree(t->d);
2057
2058                 t->d = d;
2059                 t->size = new_size;
2060         }
2061
2062
2063         t->d[t->nr++] = (struct nlink) {
2064                 .inum           = inum,
2065                 .snapshot       = snapshot,
2066         };
2067
2068         return 0;
2069 }
2070
2071 static int nlink_cmp(const void *_l, const void *_r)
2072 {
2073         const struct nlink *l = _l;
2074         const struct nlink *r = _r;
2075
2076         return cmp_int(l->inum, r->inum) ?: cmp_int(l->snapshot, r->snapshot);
2077 }
2078
2079 static void inc_link(struct bch_fs *c, struct snapshots_seen *s,
2080                      struct nlink_table *links,
2081                      u64 range_start, u64 range_end, u64 inum, u32 snapshot)
2082 {
2083         struct nlink *link, key = {
2084                 .inum = inum, .snapshot = U32_MAX,
2085         };
2086
2087         if (inum < range_start || inum >= range_end)
2088                 return;
2089
2090         link = __inline_bsearch(&key, links->d, links->nr,
2091                                 sizeof(links->d[0]), nlink_cmp);
2092         if (!link)
2093                 return;
2094
2095         while (link > links->d && link[0].inum == link[-1].inum)
2096                 --link;
2097
2098         for (; link < links->d + links->nr && link->inum == inum; link++)
2099                 if (ref_visible(c, s, snapshot, link->snapshot)) {
2100                         link->count++;
2101                         if (link->snapshot >= snapshot)
2102                                 break;
2103                 }
2104 }
2105
2106 noinline_for_stack
2107 static int check_nlinks_find_hardlinks(struct bch_fs *c,
2108                                        struct nlink_table *t,
2109                                        u64 start, u64 *end)
2110 {
2111         struct btree_trans trans;
2112         struct btree_iter iter;
2113         struct bkey_s_c k;
2114         struct bch_inode_unpacked u;
2115         int ret = 0;
2116
2117         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
2118
2119         for_each_btree_key(&trans, iter, BTREE_ID_inodes,
2120                            POS(0, start),
2121                            BTREE_ITER_INTENT|
2122                            BTREE_ITER_PREFETCH|
2123                            BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
2124                 if (!bkey_is_inode(k.k))
2125                         continue;
2126
2127                 /* Should never fail, checked by bch2_inode_invalid: */
2128                 BUG_ON(bch2_inode_unpack(k, &u));
2129
2130                 /*
2131                  * Backpointer and directory structure checks are sufficient for
2132                  * directories, since they can't have hardlinks:
2133                  */
2134                 if (S_ISDIR(le16_to_cpu(u.bi_mode)))
2135                         continue;
2136
2137                 if (!u.bi_nlink)
2138                         continue;
2139
2140                 ret = add_nlink(c, t, k.k->p.offset, k.k->p.snapshot);
2141                 if (ret) {
2142                         *end = k.k->p.offset;
2143                         ret = 0;
2144                         break;
2145                 }
2146
2147         }
2148         bch2_trans_iter_exit(&trans, &iter);
2149         bch2_trans_exit(&trans);
2150
2151         if (ret)
2152                 bch_err(c, "error in fsck: btree error %i while walking inodes", ret);
2153
2154         return ret;
2155 }
2156
2157 noinline_for_stack
2158 static int check_nlinks_walk_dirents(struct bch_fs *c, struct nlink_table *links,
2159                                      u64 range_start, u64 range_end)
2160 {
2161         struct btree_trans trans;
2162         struct snapshots_seen s;
2163         struct btree_iter iter;
2164         struct bkey_s_c k;
2165         struct bkey_s_c_dirent d;
2166         int ret;
2167
2168         snapshots_seen_init(&s);
2169
2170         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
2171
2172         for_each_btree_key(&trans, iter, BTREE_ID_dirents, POS_MIN,
2173                            BTREE_ITER_INTENT|
2174                            BTREE_ITER_PREFETCH|
2175                            BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
2176                 ret = snapshots_seen_update(c, &s, iter.btree_id, k.k->p);
2177                 if (ret)
2178                         break;
2179
2180                 switch (k.k->type) {
2181                 case KEY_TYPE_dirent:
2182                         d = bkey_s_c_to_dirent(k);
2183
2184                         if (d.v->d_type != DT_DIR &&
2185                             d.v->d_type != DT_SUBVOL)
2186                                 inc_link(c, &s, links, range_start, range_end,
2187                                          le64_to_cpu(d.v->d_inum),
2188                                          bch2_snapshot_equiv(c, d.k->p.snapshot));
2189                         break;
2190                 }
2191         }
2192         bch2_trans_iter_exit(&trans, &iter);
2193
2194         if (ret)
2195                 bch_err(c, "error in fsck: btree error %i while walking dirents", ret);
2196
2197         bch2_trans_exit(&trans);
2198         snapshots_seen_exit(&s);
2199         return ret;
2200 }
2201
2202 static int check_nlinks_update_inode(struct btree_trans *trans, struct btree_iter *iter,
2203                                      struct bkey_s_c k,
2204                                      struct nlink_table *links,
2205                                      size_t *idx, u64 range_end)
2206 {
2207         struct bch_fs *c = trans->c;
2208         struct bch_inode_unpacked u;
2209         struct nlink *link = &links->d[*idx];
2210         int ret = 0;
2211
2212         if (k.k->p.offset >= range_end)
2213                 return 1;
2214
2215         if (!bkey_is_inode(k.k))
2216                 return 0;
2217
2218         BUG_ON(bch2_inode_unpack(k, &u));
2219
2220         if (S_ISDIR(le16_to_cpu(u.bi_mode)))
2221                 return 0;
2222
2223         if (!u.bi_nlink)
2224                 return 0;
2225
2226         while ((cmp_int(link->inum, k.k->p.offset) ?:
2227                 cmp_int(link->snapshot, k.k->p.snapshot)) < 0) {
2228                 BUG_ON(*idx == links->nr);
2229                 link = &links->d[++*idx];
2230         }
2231
2232         if (fsck_err_on(bch2_inode_nlink_get(&u) != link->count, c,
2233                         "inode %llu type %s has wrong i_nlink (%u, should be %u)",
2234                         u.bi_inum, bch2_d_types[mode_to_type(u.bi_mode)],
2235                         bch2_inode_nlink_get(&u), link->count)) {
2236                 bch2_inode_nlink_set(&u, link->count);
2237                 ret = __write_inode(trans, &u, k.k->p.snapshot);
2238         }
2239 fsck_err:
2240         return ret;
2241 }
2242
2243 noinline_for_stack
2244 static int check_nlinks_update_hardlinks(struct bch_fs *c,
2245                                struct nlink_table *links,
2246                                u64 range_start, u64 range_end)
2247 {
2248         struct btree_trans trans;
2249         struct btree_iter iter;
2250         struct bkey_s_c k;
2251         size_t idx = 0;
2252         int ret = 0;
2253
2254         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
2255
2256         ret = for_each_btree_key_commit(&trans, iter, BTREE_ID_inodes,
2257                         POS(0, range_start),
2258                         BTREE_ITER_INTENT|BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
2259                         NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
2260                 check_nlinks_update_inode(&trans, &iter, k, links, &idx, range_end));
2261
2262         bch2_trans_exit(&trans);
2263
2264         if (ret < 0) {
2265                 bch_err(c, "error in fsck: btree error %i while walking inodes", ret);
2266                 return ret;
2267         }
2268
2269         return 0;
2270 }
2271
2272 noinline_for_stack
2273 static int check_nlinks(struct bch_fs *c)
2274 {
2275         struct nlink_table links = { 0 };
2276         u64 this_iter_range_start, next_iter_range_start = 0;
2277         int ret = 0;
2278
2279         bch_verbose(c, "checking inode nlinks");
2280
2281         do {
2282                 this_iter_range_start = next_iter_range_start;
2283                 next_iter_range_start = U64_MAX;
2284
2285                 ret = check_nlinks_find_hardlinks(c, &links,
2286                                                   this_iter_range_start,
2287                                                   &next_iter_range_start);
2288
2289                 ret = check_nlinks_walk_dirents(c, &links,
2290                                           this_iter_range_start,
2291                                           next_iter_range_start);
2292                 if (ret)
2293                         break;
2294
2295                 ret = check_nlinks_update_hardlinks(c, &links,
2296                                          this_iter_range_start,
2297                                          next_iter_range_start);
2298                 if (ret)
2299                         break;
2300
2301                 links.nr = 0;
2302         } while (next_iter_range_start != U64_MAX);
2303
2304         kvfree(links.d);
2305
2306         return ret;
2307 }
2308
2309 static int fix_reflink_p_key(struct btree_trans *trans, struct btree_iter *iter,
2310                              struct bkey_s_c k)
2311 {
2312         struct bkey_s_c_reflink_p p;
2313         struct bkey_i_reflink_p *u;
2314         int ret;
2315
2316         if (k.k->type != KEY_TYPE_reflink_p)
2317                 return 0;
2318
2319         p = bkey_s_c_to_reflink_p(k);
2320
2321         if (!p.v->front_pad && !p.v->back_pad)
2322                 return 0;
2323
2324         u = bch2_trans_kmalloc(trans, sizeof(*u));
2325         ret = PTR_ERR_OR_ZERO(u);
2326         if (ret)
2327                 return ret;
2328
2329         bkey_reassemble(&u->k_i, k);
2330         u->v.front_pad  = 0;
2331         u->v.back_pad   = 0;
2332
2333         return bch2_trans_update(trans, iter, &u->k_i, BTREE_TRIGGER_NORUN);
2334 }
2335
2336 noinline_for_stack
2337 static int fix_reflink_p(struct bch_fs *c)
2338 {
2339         struct btree_trans trans;
2340         struct btree_iter iter;
2341         struct bkey_s_c k;
2342         int ret;
2343
2344         if (c->sb.version >= bcachefs_metadata_version_reflink_p_fix)
2345                 return 0;
2346
2347         bch_verbose(c, "fixing reflink_p keys");
2348
2349         bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
2350
2351         ret = for_each_btree_key_commit(&trans, iter,
2352                         BTREE_ID_extents, POS_MIN,
2353                         BTREE_ITER_INTENT|BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
2354                         NULL, NULL, BTREE_INSERT_NOFAIL|BTREE_INSERT_LAZY_RW,
2355                 fix_reflink_p_key(&trans, &iter, k));
2356
2357         bch2_trans_exit(&trans);
2358         return ret;
2359 }
2360
2361 /*
2362  * Checks for inconsistencies that shouldn't happen, unless we have a bug.
2363  * Doesn't fix them yet, mainly because they haven't yet been observed:
2364  */
2365 int bch2_fsck_full(struct bch_fs *c)
2366 {
2367         int ret;
2368 again:
2369         ret =   bch2_fs_check_snapshots(c) ?:
2370                 bch2_fs_check_subvols(c) ?:
2371                 bch2_delete_dead_snapshots(c) ?:
2372                 check_inodes(c, true) ?:
2373                 check_extents(c) ?:
2374                 check_dirents(c) ?:
2375                 check_xattrs(c) ?:
2376                 check_root(c) ?:
2377                 check_directory_structure(c) ?:
2378                 check_nlinks(c) ?:
2379                 fix_reflink_p(c);
2380
2381         if (bch2_err_matches(ret, BCH_ERR_need_snapshot_cleanup)) {
2382                 set_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags);
2383                 goto again;
2384         }
2385
2386         return ret;
2387 }
2388
2389 int bch2_fsck_walk_inodes_only(struct bch_fs *c)
2390 {
2391         return  bch2_fs_check_snapshots(c) ?:
2392                 bch2_fs_check_subvols(c) ?:
2393                 bch2_delete_dead_snapshots(c) ?:
2394                 check_inodes(c, false);
2395 }