]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/fsck.c
move Rust sources to top level, C sources into c_src
[bcachefs-tools-debian] / libbcachefs / fsck.c
diff --git a/libbcachefs/fsck.c b/libbcachefs/fsck.c
deleted file mode 100644 (file)
index 4f0ecd6..0000000
+++ /dev/null
@@ -1,2394 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-#include "bcachefs.h"
-#include "bkey_buf.h"
-#include "btree_cache.h"
-#include "btree_update.h"
-#include "buckets.h"
-#include "darray.h"
-#include "dirent.h"
-#include "error.h"
-#include "fs-common.h"
-#include "fsck.h"
-#include "inode.h"
-#include "keylist.h"
-#include "recovery.h"
-#include "snapshot.h"
-#include "super.h"
-#include "xattr.h"
-
-#include <linux/bsearch.h>
-#include <linux/dcache.h> /* struct qstr */
-
-/*
- * XXX: this is handling transaction restarts without returning
- * -BCH_ERR_transaction_restart_nested, this is not how we do things anymore:
- */
-static s64 bch2_count_inode_sectors(struct btree_trans *trans, u64 inum,
-                                   u32 snapshot)
-{
-       u64 sectors = 0;
-
-       int ret = for_each_btree_key_upto(trans, iter, BTREE_ID_extents,
-                               SPOS(inum, 0, snapshot),
-                               POS(inum, U64_MAX),
-                               0, k, ({
-               if (bkey_extent_is_allocation(k.k))
-                       sectors += k.k->size;
-               0;
-       }));
-
-       return ret ?: sectors;
-}
-
-static s64 bch2_count_subdirs(struct btree_trans *trans, u64 inum,
-                                   u32 snapshot)
-{
-       u64 subdirs = 0;
-
-       int ret = for_each_btree_key_upto(trans, iter, BTREE_ID_dirents,
-                                   SPOS(inum, 0, snapshot),
-                                   POS(inum, U64_MAX),
-                                   0, k, ({
-               if (k.k->type == KEY_TYPE_dirent &&
-                   bkey_s_c_to_dirent(k).v->d_type == DT_DIR)
-                       subdirs++;
-               0;
-       }));
-
-       return ret ?: subdirs;
-}
-
-static int subvol_lookup(struct btree_trans *trans, u32 subvol,
-                        u32 *snapshot, u64 *inum)
-{
-       struct bch_subvolume s;
-       int ret;
-
-       ret = bch2_subvolume_get(trans, subvol, false, 0, &s);
-
-       *snapshot = le32_to_cpu(s.snapshot);
-       *inum = le64_to_cpu(s.inode);
-       return ret;
-}
-
-static int lookup_first_inode(struct btree_trans *trans, u64 inode_nr,
-                             struct bch_inode_unpacked *inode)
-{
-       struct btree_iter iter;
-       struct bkey_s_c k;
-       int ret;
-
-       bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes,
-                            POS(0, inode_nr),
-                            BTREE_ITER_ALL_SNAPSHOTS);
-       k = bch2_btree_iter_peek(&iter);
-       ret = bkey_err(k);
-       if (ret)
-               goto err;
-
-       if (!k.k || !bkey_eq(k.k->p, POS(0, inode_nr))) {
-               ret = -BCH_ERR_ENOENT_inode;
-               goto err;
-       }
-
-       ret = bch2_inode_unpack(k, inode);
-err:
-       bch_err_msg(trans->c, ret, "fetching inode %llu", inode_nr);
-       bch2_trans_iter_exit(trans, &iter);
-       return ret;
-}
-
-static int lookup_inode(struct btree_trans *trans, u64 inode_nr,
-                         struct bch_inode_unpacked *inode,
-                         u32 *snapshot)
-{
-       struct btree_iter iter;
-       struct bkey_s_c k;
-       int ret;
-
-       k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_inodes,
-                              SPOS(0, inode_nr, *snapshot), 0);
-       ret = bkey_err(k);
-       if (ret)
-               goto err;
-
-       ret = bkey_is_inode(k.k)
-               ? bch2_inode_unpack(k, inode)
-               : -BCH_ERR_ENOENT_inode;
-       if (!ret)
-               *snapshot = iter.pos.snapshot;
-err:
-       bch_err_msg(trans->c, ret, "fetching inode %llu:%u", inode_nr, *snapshot);
-       bch2_trans_iter_exit(trans, &iter);
-       return ret;
-}
-
-static int __lookup_dirent(struct btree_trans *trans,
-                          struct bch_hash_info hash_info,
-                          subvol_inum dir, struct qstr *name,
-                          u64 *target, unsigned *type)
-{
-       struct btree_iter iter;
-       struct bkey_s_c_dirent d;
-       int ret;
-
-       ret = bch2_hash_lookup(trans, &iter, bch2_dirent_hash_desc,
-                              &hash_info, dir, name, 0);
-       if (ret)
-               return ret;
-
-       d = bkey_s_c_to_dirent(bch2_btree_iter_peek_slot(&iter));
-       *target = le64_to_cpu(d.v->d_inum);
-       *type = d.v->d_type;
-       bch2_trans_iter_exit(trans, &iter);
-       return 0;
-}
-
-static int __write_inode(struct btree_trans *trans,
-                        struct bch_inode_unpacked *inode,
-                        u32 snapshot)
-{
-       struct bkey_inode_buf *inode_p =
-               bch2_trans_kmalloc(trans, sizeof(*inode_p));
-
-       if (IS_ERR(inode_p))
-               return PTR_ERR(inode_p);
-
-       bch2_inode_pack(inode_p, inode);
-       inode_p->inode.k.p.snapshot = snapshot;
-
-       return bch2_btree_insert_nonextent(trans, BTREE_ID_inodes,
-                               &inode_p->inode.k_i,
-                               BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-}
-
-static int fsck_write_inode(struct btree_trans *trans,
-                           struct bch_inode_unpacked *inode,
-                           u32 snapshot)
-{
-       int ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
-                           __write_inode(trans, inode, snapshot));
-       bch_err_fn(trans->c, ret);
-       return ret;
-}
-
-static int __remove_dirent(struct btree_trans *trans, struct bpos pos)
-{
-       struct bch_fs *c = trans->c;
-       struct btree_iter iter;
-       struct bch_inode_unpacked dir_inode;
-       struct bch_hash_info dir_hash_info;
-       int ret;
-
-       ret = lookup_first_inode(trans, pos.inode, &dir_inode);
-       if (ret)
-               goto err;
-
-       dir_hash_info = bch2_hash_info_init(c, &dir_inode);
-
-       bch2_trans_iter_init(trans, &iter, BTREE_ID_dirents, pos, BTREE_ITER_INTENT);
-
-       ret = bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
-                                 &dir_hash_info, &iter,
-                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-       bch2_trans_iter_exit(trans, &iter);
-err:
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-/* Get lost+found, create if it doesn't exist: */
-static int lookup_lostfound(struct btree_trans *trans, u32 snapshot,
-                           struct bch_inode_unpacked *lostfound)
-{
-       struct bch_fs *c = trans->c;
-       struct qstr lostfound_str = QSTR("lost+found");
-       u64 inum = 0;
-       unsigned d_type = 0;
-       int ret;
-
-       struct bch_snapshot_tree st;
-       ret = bch2_snapshot_tree_lookup(trans,
-                       bch2_snapshot_tree(c, snapshot), &st);
-       if (ret)
-               return ret;
-
-       subvol_inum root_inum = { .subvol = le32_to_cpu(st.master_subvol) };
-       u32 subvol_snapshot;
-
-       ret = subvol_lookup(trans, le32_to_cpu(st.master_subvol),
-                           &subvol_snapshot, &root_inum.inum);
-       bch_err_msg(c, ret, "looking up root subvol");
-       if (ret)
-               return ret;
-
-       struct bch_inode_unpacked root_inode;
-       struct bch_hash_info root_hash_info;
-       ret = lookup_inode(trans, root_inum.inum, &root_inode, &snapshot);
-       bch_err_msg(c, ret, "looking up root inode");
-       if (ret)
-               return ret;
-
-       root_hash_info = bch2_hash_info_init(c, &root_inode);
-
-       ret = __lookup_dirent(trans, root_hash_info, root_inum,
-                             &lostfound_str, &inum, &d_type);
-       if (bch2_err_matches(ret, ENOENT))
-               goto create_lostfound;
-
-       bch_err_fn(c, ret);
-       if (ret)
-               return ret;
-
-       if (d_type != DT_DIR) {
-               bch_err(c, "error looking up lost+found: not a directory");
-               return -BCH_ERR_ENOENT_not_directory;
-       }
-
-       /*
-        * The bch2_check_dirents pass has already run, dangling dirents
-        * shouldn't exist here:
-        */
-       return lookup_inode(trans, inum, lostfound, &snapshot);
-
-create_lostfound:
-       /*
-        * XXX: we could have a nicer log message here  if we had a nice way to
-        * walk backpointers to print a path
-        */
-       bch_notice(c, "creating lost+found in snapshot %u", le32_to_cpu(st.root_snapshot));
-
-       u64 now = bch2_current_time(c);
-       struct btree_iter lostfound_iter = { NULL };
-       u64 cpu = raw_smp_processor_id();
-
-       bch2_inode_init_early(c, lostfound);
-       bch2_inode_init_late(lostfound, now, 0, 0, S_IFDIR|0700, 0, &root_inode);
-       lostfound->bi_dir = root_inode.bi_inum;
-
-       root_inode.bi_nlink++;
-
-       ret = bch2_inode_create(trans, &lostfound_iter, lostfound, snapshot, cpu);
-       if (ret)
-               goto err;
-
-       bch2_btree_iter_set_snapshot(&lostfound_iter, snapshot);
-       ret = bch2_btree_iter_traverse(&lostfound_iter);
-       if (ret)
-               goto err;
-
-       ret =   bch2_dirent_create_snapshot(trans,
-                               root_inode.bi_inum, snapshot, &root_hash_info,
-                               mode_to_type(lostfound->bi_mode),
-                               &lostfound_str,
-                               lostfound->bi_inum,
-                               &lostfound->bi_dir_offset,
-                               BCH_HASH_SET_MUST_CREATE) ?:
-               bch2_inode_write_flags(trans, &lostfound_iter, lostfound,
-                                      BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-err:
-       bch_err_msg(c, ret, "creating lost+found");
-       bch2_trans_iter_exit(trans, &lostfound_iter);
-       return ret;
-}
-
-static int reattach_inode(struct btree_trans *trans,
-                         struct bch_inode_unpacked *inode,
-                         u32 inode_snapshot)
-{
-       struct bch_hash_info dir_hash;
-       struct bch_inode_unpacked lostfound;
-       char name_buf[20];
-       struct qstr name;
-       u64 dir_offset = 0;
-       int ret;
-
-       ret = lookup_lostfound(trans, inode_snapshot, &lostfound);
-       if (ret)
-               return ret;
-
-       if (S_ISDIR(inode->bi_mode)) {
-               lostfound.bi_nlink++;
-
-               ret = __write_inode(trans, &lostfound, U32_MAX);
-               if (ret)
-                       return ret;
-       }
-
-       dir_hash = bch2_hash_info_init(trans->c, &lostfound);
-
-       snprintf(name_buf, sizeof(name_buf), "%llu", inode->bi_inum);
-       name = (struct qstr) QSTR(name_buf);
-
-       ret = bch2_dirent_create_snapshot(trans,
-                               lostfound.bi_inum, inode_snapshot,
-                               &dir_hash,
-                               inode_d_type(inode),
-                               &name, inode->bi_inum, &dir_offset,
-                               BCH_HASH_SET_MUST_CREATE);
-       if (ret)
-               return ret;
-
-       inode->bi_dir           = lostfound.bi_inum;
-       inode->bi_dir_offset    = dir_offset;
-
-       return __write_inode(trans, inode, inode_snapshot);
-}
-
-static int remove_backpointer(struct btree_trans *trans,
-                             struct bch_inode_unpacked *inode)
-{
-       struct btree_iter iter;
-       struct bkey_s_c_dirent d;
-       int ret;
-
-       d = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_dirents,
-                                    POS(inode->bi_dir, inode->bi_dir_offset), 0,
-                                    dirent);
-       ret =   bkey_err(d) ?:
-               __remove_dirent(trans, d.k->p);
-       bch2_trans_iter_exit(trans, &iter);
-       return ret;
-}
-
-struct snapshots_seen_entry {
-       u32                             id;
-       u32                             equiv;
-};
-
-struct snapshots_seen {
-       struct bpos                     pos;
-       DARRAY(struct snapshots_seen_entry) ids;
-};
-
-static inline void snapshots_seen_exit(struct snapshots_seen *s)
-{
-       darray_exit(&s->ids);
-}
-
-static inline void snapshots_seen_init(struct snapshots_seen *s)
-{
-       memset(s, 0, sizeof(*s));
-}
-
-static int snapshots_seen_add_inorder(struct bch_fs *c, struct snapshots_seen *s, u32 id)
-{
-       struct snapshots_seen_entry *i, n = {
-               .id     = id,
-               .equiv  = bch2_snapshot_equiv(c, id),
-       };
-       int ret = 0;
-
-       __darray_for_each(s->ids, i) {
-               if (i->id == id)
-                       return 0;
-               if (i->id > id)
-                       break;
-       }
-
-       ret = darray_insert_item(&s->ids, i - s->ids.data, n);
-       if (ret)
-               bch_err(c, "error reallocating snapshots_seen table (size %zu)",
-                       s->ids.size);
-       return ret;
-}
-
-static int snapshots_seen_update(struct bch_fs *c, struct snapshots_seen *s,
-                                enum btree_id btree_id, struct bpos pos)
-{
-       struct snapshots_seen_entry n = {
-               .id     = pos.snapshot,
-               .equiv  = bch2_snapshot_equiv(c, pos.snapshot),
-       };
-       int ret = 0;
-
-       if (!bkey_eq(s->pos, pos))
-               s->ids.nr = 0;
-
-       s->pos = pos;
-       s->pos.snapshot = n.equiv;
-
-       darray_for_each(s->ids, i) {
-               if (i->id == n.id)
-                       return 0;
-
-               /*
-                * We currently don't rigorously track for snapshot cleanup
-                * needing to be run, so it shouldn't be a fsck error yet:
-                */
-               if (i->equiv == n.equiv) {
-                       bch_err(c, "snapshot deletion did not finish:\n"
-                               "  duplicate keys in btree %s at %llu:%llu snapshots %u, %u (equiv %u)\n",
-                               bch2_btree_id_str(btree_id),
-                               pos.inode, pos.offset,
-                               i->id, n.id, n.equiv);
-                       set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
-                       return bch2_run_explicit_recovery_pass(c, BCH_RECOVERY_PASS_delete_dead_snapshots);
-               }
-       }
-
-       ret = darray_push(&s->ids, n);
-       if (ret)
-               bch_err(c, "error reallocating snapshots_seen table (size %zu)",
-                       s->ids.size);
-       return ret;
-}
-
-/**
- * key_visible_in_snapshot - returns true if @id is a descendent of @ancestor,
- * and @ancestor hasn't been overwritten in @seen
- *
- * @c:         filesystem handle
- * @seen:      list of snapshot ids already seen at current position
- * @id:                descendent snapshot id
- * @ancestor:  ancestor snapshot id
- *
- * Returns:    whether key in @ancestor snapshot is visible in @id snapshot
- */
-static bool key_visible_in_snapshot(struct bch_fs *c, struct snapshots_seen *seen,
-                                   u32 id, u32 ancestor)
-{
-       ssize_t i;
-
-       EBUG_ON(id > ancestor);
-       EBUG_ON(!bch2_snapshot_is_equiv(c, id));
-       EBUG_ON(!bch2_snapshot_is_equiv(c, ancestor));
-
-       /* @ancestor should be the snapshot most recently added to @seen */
-       EBUG_ON(ancestor != seen->pos.snapshot);
-       EBUG_ON(ancestor != seen->ids.data[seen->ids.nr - 1].equiv);
-
-       if (id == ancestor)
-               return true;
-
-       if (!bch2_snapshot_is_ancestor(c, id, ancestor))
-               return false;
-
-       /*
-        * We know that @id is a descendant of @ancestor, we're checking if
-        * we've seen a key that overwrote @ancestor - i.e. also a descendent of
-        * @ascestor and with @id as a descendent.
-        *
-        * But we already know that we're scanning IDs between @id and @ancestor
-        * numerically, since snapshot ID lists are kept sorted, so if we find
-        * an id that's an ancestor of @id we're done:
-        */
-
-       for (i = seen->ids.nr - 2;
-            i >= 0 && seen->ids.data[i].equiv >= id;
-            --i)
-               if (bch2_snapshot_is_ancestor(c, id, seen->ids.data[i].equiv))
-                       return false;
-
-       return true;
-}
-
-/**
- * ref_visible - given a key with snapshot id @src that points to a key with
- * snapshot id @dst, test whether there is some snapshot in which @dst is
- * visible.
- *
- * @c:         filesystem handle
- * @s:         list of snapshot IDs already seen at @src
- * @src:       snapshot ID of src key
- * @dst:       snapshot ID of dst key
- * Returns:    true if there is some snapshot in which @dst is visible
- *
- * Assumes we're visiting @src keys in natural key order
- */
-static bool ref_visible(struct bch_fs *c, struct snapshots_seen *s,
-                       u32 src, u32 dst)
-{
-       return dst <= src
-               ? key_visible_in_snapshot(c, s, dst, src)
-               : bch2_snapshot_is_ancestor(c, src, dst);
-}
-
-static int ref_visible2(struct bch_fs *c,
-                       u32 src, struct snapshots_seen *src_seen,
-                       u32 dst, struct snapshots_seen *dst_seen)
-{
-       src = bch2_snapshot_equiv(c, src);
-       dst = bch2_snapshot_equiv(c, dst);
-
-       if (dst > src) {
-               swap(dst, src);
-               swap(dst_seen, src_seen);
-       }
-       return key_visible_in_snapshot(c, src_seen, dst, src);
-}
-
-#define for_each_visible_inode(_c, _s, _w, _snapshot, _i)                              \
-       for (_i = (_w)->inodes.data; _i < (_w)->inodes.data + (_w)->inodes.nr &&        \
-            (_i)->snapshot <= (_snapshot); _i++)                                       \
-               if (key_visible_in_snapshot(_c, _s, _i->snapshot, _snapshot))
-
-struct inode_walker_entry {
-       struct bch_inode_unpacked inode;
-       u32                     snapshot;
-       bool                    seen_this_pos;
-       u64                     count;
-};
-
-struct inode_walker {
-       bool                            first_this_inode;
-       bool                            recalculate_sums;
-       struct bpos                     last_pos;
-
-       DARRAY(struct inode_walker_entry) inodes;
-};
-
-static void inode_walker_exit(struct inode_walker *w)
-{
-       darray_exit(&w->inodes);
-}
-
-static struct inode_walker inode_walker_init(void)
-{
-       return (struct inode_walker) { 0, };
-}
-
-static int add_inode(struct bch_fs *c, struct inode_walker *w,
-                    struct bkey_s_c inode)
-{
-       struct bch_inode_unpacked u;
-
-       BUG_ON(bch2_inode_unpack(inode, &u));
-
-       return darray_push(&w->inodes, ((struct inode_walker_entry) {
-               .inode          = u,
-               .snapshot       = bch2_snapshot_equiv(c, inode.k->p.snapshot),
-       }));
-}
-
-static int get_inodes_all_snapshots(struct btree_trans *trans,
-                                   struct inode_walker *w, u64 inum)
-{
-       struct bch_fs *c = trans->c;
-       struct btree_iter iter;
-       struct bkey_s_c k;
-       int ret;
-
-       w->recalculate_sums = false;
-       w->inodes.nr = 0;
-
-       for_each_btree_key_norestart(trans, iter, BTREE_ID_inodes, POS(0, inum),
-                                    BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
-               if (k.k->p.offset != inum)
-                       break;
-
-               if (bkey_is_inode(k.k))
-                       add_inode(c, w, k);
-       }
-       bch2_trans_iter_exit(trans, &iter);
-
-       if (ret)
-               return ret;
-
-       w->first_this_inode = true;
-       return 0;
-}
-
-static struct inode_walker_entry *
-lookup_inode_for_snapshot(struct bch_fs *c, struct inode_walker *w,
-                         u32 snapshot, bool is_whiteout)
-{
-       struct inode_walker_entry *i;
-
-       snapshot = bch2_snapshot_equiv(c, snapshot);
-
-       __darray_for_each(w->inodes, i)
-               if (bch2_snapshot_is_ancestor(c, snapshot, i->snapshot))
-                       goto found;
-
-       return NULL;
-found:
-       BUG_ON(snapshot > i->snapshot);
-
-       if (snapshot != i->snapshot && !is_whiteout) {
-               struct inode_walker_entry new = *i;
-               size_t pos;
-               int ret;
-
-               new.snapshot = snapshot;
-               new.count = 0;
-
-               bch_info(c, "have key for inode %llu:%u but have inode in ancestor snapshot %u",
-                        w->last_pos.inode, snapshot, i->snapshot);
-
-               while (i > w->inodes.data && i[-1].snapshot > snapshot)
-                       --i;
-
-               pos = i - w->inodes.data;
-               ret = darray_insert_item(&w->inodes, pos, new);
-               if (ret)
-                       return ERR_PTR(ret);
-
-               i = w->inodes.data + pos;
-       }
-
-       return i;
-}
-
-static struct inode_walker_entry *walk_inode(struct btree_trans *trans,
-                                            struct inode_walker *w, struct bpos pos,
-                                            bool is_whiteout)
-{
-       if (w->last_pos.inode != pos.inode) {
-               int ret = get_inodes_all_snapshots(trans, w, pos.inode);
-               if (ret)
-                       return ERR_PTR(ret);
-       } else if (bkey_cmp(w->last_pos, pos)) {
-               darray_for_each(w->inodes, i)
-                       i->seen_this_pos = false;
-       }
-
-       w->last_pos = pos;
-
-       return lookup_inode_for_snapshot(trans->c, w, pos.snapshot, is_whiteout);
-}
-
-static int __get_visible_inodes(struct btree_trans *trans,
-                               struct inode_walker *w,
-                               struct snapshots_seen *s,
-                               u64 inum)
-{
-       struct bch_fs *c = trans->c;
-       struct btree_iter iter;
-       struct bkey_s_c k;
-       int ret;
-
-       w->inodes.nr = 0;
-
-       for_each_btree_key_norestart(trans, iter, BTREE_ID_inodes, POS(0, inum),
-                          BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
-               u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
-
-               if (k.k->p.offset != inum)
-                       break;
-
-               if (!ref_visible(c, s, s->pos.snapshot, equiv))
-                       continue;
-
-               if (bkey_is_inode(k.k))
-                       add_inode(c, w, k);
-
-               if (equiv >= s->pos.snapshot)
-                       break;
-       }
-       bch2_trans_iter_exit(trans, &iter);
-
-       return ret;
-}
-
-static int check_key_has_snapshot(struct btree_trans *trans,
-                                 struct btree_iter *iter,
-                                 struct bkey_s_c k)
-{
-       struct bch_fs *c = trans->c;
-       struct printbuf buf = PRINTBUF;
-       int ret = 0;
-
-       if (mustfix_fsck_err_on(!bch2_snapshot_equiv(c, k.k->p.snapshot), c,
-                               bkey_in_missing_snapshot,
-                               "key in missing snapshot: %s",
-                               (bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-               ret = bch2_btree_delete_at(trans, iter,
-                                           BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?: 1;
-fsck_err:
-       printbuf_exit(&buf);
-       return ret;
-}
-
-static int hash_redo_key(struct btree_trans *trans,
-                        const struct bch_hash_desc desc,
-                        struct bch_hash_info *hash_info,
-                        struct btree_iter *k_iter, struct bkey_s_c k)
-{
-       struct bkey_i *delete;
-       struct bkey_i *tmp;
-
-       delete = bch2_trans_kmalloc(trans, sizeof(*delete));
-       if (IS_ERR(delete))
-               return PTR_ERR(delete);
-
-       tmp = bch2_bkey_make_mut_noupdate(trans, k);
-       if (IS_ERR(tmp))
-               return PTR_ERR(tmp);
-
-       bkey_init(&delete->k);
-       delete->k.p = k_iter->pos;
-       return  bch2_btree_iter_traverse(k_iter) ?:
-               bch2_trans_update(trans, k_iter, delete, 0) ?:
-               bch2_hash_set_snapshot(trans, desc, hash_info,
-                                      (subvol_inum) { 0, k.k->p.inode },
-                                      k.k->p.snapshot, tmp,
-                                      BCH_HASH_SET_MUST_CREATE,
-                                      BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
-               bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc);
-}
-
-static int hash_check_key(struct btree_trans *trans,
-                         const struct bch_hash_desc desc,
-                         struct bch_hash_info *hash_info,
-                         struct btree_iter *k_iter, struct bkey_s_c hash_k)
-{
-       struct bch_fs *c = trans->c;
-       struct btree_iter iter = { NULL };
-       struct printbuf buf = PRINTBUF;
-       struct bkey_s_c k;
-       u64 hash;
-       int ret = 0;
-
-       if (hash_k.k->type != desc.key_type)
-               return 0;
-
-       hash = desc.hash_bkey(hash_info, hash_k);
-
-       if (likely(hash == hash_k.k->p.offset))
-               return 0;
-
-       if (hash_k.k->p.offset < hash)
-               goto bad_hash;
-
-       for_each_btree_key_norestart(trans, iter, desc.btree_id,
-                                    SPOS(hash_k.k->p.inode, hash, hash_k.k->p.snapshot),
-                                    BTREE_ITER_SLOTS, k, ret) {
-               if (bkey_eq(k.k->p, hash_k.k->p))
-                       break;
-
-               if (fsck_err_on(k.k->type == desc.key_type &&
-                               !desc.cmp_bkey(k, hash_k), c,
-                               hash_table_key_duplicate,
-                               "duplicate hash table keys:\n%s",
-                               (printbuf_reset(&buf),
-                                bch2_bkey_val_to_text(&buf, c, hash_k),
-                                buf.buf))) {
-                       ret = bch2_hash_delete_at(trans, desc, hash_info, k_iter, 0) ?: 1;
-                       break;
-               }
-
-               if (bkey_deleted(k.k)) {
-                       bch2_trans_iter_exit(trans, &iter);
-                       goto bad_hash;
-               }
-       }
-out:
-       bch2_trans_iter_exit(trans, &iter);
-       printbuf_exit(&buf);
-       return ret;
-bad_hash:
-       if (fsck_err(c, hash_table_key_wrong_offset,
-                    "hash table key at wrong offset: btree %s inode %llu offset %llu, hashed to %llu\n%s",
-                    bch2_btree_id_str(desc.btree_id), hash_k.k->p.inode, hash_k.k->p.offset, hash,
-                    (printbuf_reset(&buf),
-                     bch2_bkey_val_to_text(&buf, c, hash_k), buf.buf))) {
-               ret = hash_redo_key(trans, desc, hash_info, k_iter, hash_k);
-               bch_err_fn(c, ret);
-               if (ret)
-                       return ret;
-               ret = -BCH_ERR_transaction_restart_nested;
-       }
-fsck_err:
-       goto out;
-}
-
-static int check_inode_deleted_list(struct btree_trans *trans, struct bpos p)
-{
-       struct btree_iter iter;
-       struct bkey_s_c k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_deleted_inodes, p, 0);
-       int ret = bkey_err(k);
-       if (ret)
-               return ret;
-
-       bch2_trans_iter_exit(trans, &iter);
-       return k.k->type == KEY_TYPE_set;
-}
-
-static int check_inode(struct btree_trans *trans,
-                      struct btree_iter *iter,
-                      struct bkey_s_c k,
-                      struct bch_inode_unpacked *prev,
-                      struct snapshots_seen *s,
-                      bool full)
-{
-       struct bch_fs *c = trans->c;
-       struct bch_inode_unpacked u;
-       bool do_update = false;
-       int ret;
-
-       ret = check_key_has_snapshot(trans, iter, k);
-       if (ret < 0)
-               goto err;
-       if (ret)
-               return 0;
-
-       ret = snapshots_seen_update(c, s, iter->btree_id, k.k->p);
-       if (ret)
-               goto err;
-
-       if (!bkey_is_inode(k.k))
-               return 0;
-
-       BUG_ON(bch2_inode_unpack(k, &u));
-
-       if (!full &&
-           !(u.bi_flags & (BCH_INODE_i_size_dirty|
-                           BCH_INODE_i_sectors_dirty|
-                           BCH_INODE_unlinked)))
-               return 0;
-
-       if (prev->bi_inum != u.bi_inum)
-               *prev = u;
-
-       if (fsck_err_on(prev->bi_hash_seed      != u.bi_hash_seed ||
-                       inode_d_type(prev)      != inode_d_type(&u),
-                       c, inode_snapshot_mismatch,
-                       "inodes in different snapshots don't match")) {
-               bch_err(c, "repair not implemented yet");
-               return -BCH_ERR_fsck_repair_unimplemented;
-       }
-
-       if ((u.bi_flags & (BCH_INODE_i_size_dirty|BCH_INODE_unlinked)) &&
-           bch2_key_has_snapshot_overwrites(trans, BTREE_ID_inodes, k.k->p)) {
-               struct bpos new_min_pos;
-
-               ret = bch2_propagate_key_to_snapshot_leaves(trans, iter->btree_id, k, &new_min_pos);
-               if (ret)
-                       goto err;
-
-               u.bi_flags &= ~BCH_INODE_i_size_dirty|BCH_INODE_unlinked;
-
-               ret = __write_inode(trans, &u, iter->pos.snapshot);
-               bch_err_msg(c, ret, "in fsck updating inode");
-               if (ret)
-                       return ret;
-
-               if (!bpos_eq(new_min_pos, POS_MIN))
-                       bch2_btree_iter_set_pos(iter, bpos_predecessor(new_min_pos));
-               return 0;
-       }
-
-       if (u.bi_flags & BCH_INODE_unlinked) {
-               ret = check_inode_deleted_list(trans, k.k->p);
-               if (ret < 0)
-                       return ret;
-
-               fsck_err_on(ret, c, unlinked_inode_not_on_deleted_list,
-                           "inode %llu:%u unlinked, but not on deleted list",
-                           u.bi_inum, k.k->p.snapshot);
-               ret = 0;
-       }
-
-       if (u.bi_flags & BCH_INODE_unlinked &&
-           (!c->sb.clean ||
-            fsck_err(c, inode_unlinked_but_clean,
-                     "filesystem marked clean, but inode %llu unlinked",
-                     u.bi_inum))) {
-               ret = bch2_inode_rm_snapshot(trans, u.bi_inum, iter->pos.snapshot);
-               bch_err_msg(c, ret, "in fsck deleting inode");
-               return ret;
-       }
-
-       if (u.bi_flags & BCH_INODE_i_size_dirty &&
-           (!c->sb.clean ||
-            fsck_err(c, inode_i_size_dirty_but_clean,
-                     "filesystem marked clean, but inode %llu has i_size dirty",
-                     u.bi_inum))) {
-               bch_verbose(c, "truncating inode %llu", u.bi_inum);
-
-               /*
-                * XXX: need to truncate partial blocks too here - or ideally
-                * just switch units to bytes and that issue goes away
-                */
-               ret = bch2_btree_delete_range_trans(trans, BTREE_ID_extents,
-                               SPOS(u.bi_inum, round_up(u.bi_size, block_bytes(c)) >> 9,
-                                    iter->pos.snapshot),
-                               POS(u.bi_inum, U64_MAX),
-                               0, NULL);
-               bch_err_msg(c, ret, "in fsck truncating inode");
-               if (ret)
-                       return ret;
-
-               /*
-                * We truncated without our normal sector accounting hook, just
-                * make sure we recalculate it:
-                */
-               u.bi_flags |= BCH_INODE_i_sectors_dirty;
-
-               u.bi_flags &= ~BCH_INODE_i_size_dirty;
-               do_update = true;
-       }
-
-       if (u.bi_flags & BCH_INODE_i_sectors_dirty &&
-           (!c->sb.clean ||
-            fsck_err(c, inode_i_sectors_dirty_but_clean,
-                     "filesystem marked clean, but inode %llu has i_sectors dirty",
-                     u.bi_inum))) {
-               s64 sectors;
-
-               bch_verbose(c, "recounting sectors for inode %llu",
-                           u.bi_inum);
-
-               sectors = bch2_count_inode_sectors(trans, u.bi_inum, iter->pos.snapshot);
-               if (sectors < 0) {
-                       bch_err_msg(c, sectors, "in fsck recounting inode sectors");
-                       return sectors;
-               }
-
-               u.bi_sectors = sectors;
-               u.bi_flags &= ~BCH_INODE_i_sectors_dirty;
-               do_update = true;
-       }
-
-       if (u.bi_flags & BCH_INODE_backptr_untrusted) {
-               u.bi_dir = 0;
-               u.bi_dir_offset = 0;
-               u.bi_flags &= ~BCH_INODE_backptr_untrusted;
-               do_update = true;
-       }
-
-       if (do_update) {
-               ret = __write_inode(trans, &u, iter->pos.snapshot);
-               bch_err_msg(c, ret, "in fsck updating inode");
-               if (ret)
-                       return ret;
-       }
-err:
-fsck_err:
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-int bch2_check_inodes(struct bch_fs *c)
-{
-       bool full = c->opts.fsck;
-       struct bch_inode_unpacked prev = { 0 };
-       struct snapshots_seen s;
-
-       snapshots_seen_init(&s);
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_inodes,
-                               POS_MIN,
-                               BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
-                               NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
-                       check_inode(trans, &iter, k, &prev, &s, full)));
-
-       snapshots_seen_exit(&s);
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static struct bkey_s_c_dirent dirent_get_by_pos(struct btree_trans *trans,
-                                               struct btree_iter *iter,
-                                               struct bpos pos)
-{
-       return bch2_bkey_get_iter_typed(trans, iter, BTREE_ID_dirents, pos, 0, dirent);
-}
-
-static bool inode_points_to_dirent(struct bch_inode_unpacked *inode,
-                                  struct bkey_s_c_dirent d)
-{
-       return  inode->bi_dir           == d.k->p.inode &&
-               inode->bi_dir_offset    == d.k->p.offset;
-}
-
-static bool dirent_points_to_inode(struct bkey_s_c_dirent d,
-                                  struct bch_inode_unpacked *inode)
-{
-       return d.v->d_type == DT_SUBVOL
-               ? le32_to_cpu(d.v->d_child_subvol)      == inode->bi_subvol
-               : le64_to_cpu(d.v->d_inum)              == inode->bi_inum;
-}
-
-static int check_i_sectors(struct btree_trans *trans, struct inode_walker *w)
-{
-       struct bch_fs *c = trans->c;
-       u32 restart_count = trans->restart_count;
-       int ret = 0;
-       s64 count2;
-
-       darray_for_each(w->inodes, i) {
-               if (i->inode.bi_sectors == i->count)
-                       continue;
-
-               count2 = bch2_count_inode_sectors(trans, w->last_pos.inode, i->snapshot);
-
-               if (w->recalculate_sums)
-                       i->count = count2;
-
-               if (i->count != count2) {
-                       bch_err(c, "fsck counted i_sectors wrong for inode %llu:%u: got %llu should be %llu",
-                               w->last_pos.inode, i->snapshot, i->count, count2);
-                       return -BCH_ERR_internal_fsck_err;
-               }
-
-               if (fsck_err_on(!(i->inode.bi_flags & BCH_INODE_i_sectors_dirty),
-                               c, inode_i_sectors_wrong,
-                               "inode %llu:%u has incorrect i_sectors: got %llu, should be %llu",
-                               w->last_pos.inode, i->snapshot,
-                               i->inode.bi_sectors, i->count)) {
-                       i->inode.bi_sectors = i->count;
-                       ret = fsck_write_inode(trans, &i->inode, i->snapshot);
-                       if (ret)
-                               break;
-               }
-       }
-fsck_err:
-       bch_err_fn(c, ret);
-       return ret ?: trans_was_restarted(trans, restart_count);
-}
-
-struct extent_end {
-       u32                     snapshot;
-       u64                     offset;
-       struct snapshots_seen   seen;
-};
-
-struct extent_ends {
-       struct bpos                     last_pos;
-       DARRAY(struct extent_end)       e;
-};
-
-static void extent_ends_reset(struct extent_ends *extent_ends)
-{
-       darray_for_each(extent_ends->e, i)
-               snapshots_seen_exit(&i->seen);
-       extent_ends->e.nr = 0;
-}
-
-static void extent_ends_exit(struct extent_ends *extent_ends)
-{
-       extent_ends_reset(extent_ends);
-       darray_exit(&extent_ends->e);
-}
-
-static void extent_ends_init(struct extent_ends *extent_ends)
-{
-       memset(extent_ends, 0, sizeof(*extent_ends));
-}
-
-static int extent_ends_at(struct bch_fs *c,
-                         struct extent_ends *extent_ends,
-                         struct snapshots_seen *seen,
-                         struct bkey_s_c k)
-{
-       struct extent_end *i, n = (struct extent_end) {
-               .offset         = k.k->p.offset,
-               .snapshot       = k.k->p.snapshot,
-               .seen           = *seen,
-       };
-
-       n.seen.ids.data = kmemdup(seen->ids.data,
-                             sizeof(seen->ids.data[0]) * seen->ids.size,
-                             GFP_KERNEL);
-       if (!n.seen.ids.data)
-               return -BCH_ERR_ENOMEM_fsck_extent_ends_at;
-
-       __darray_for_each(extent_ends->e, i) {
-               if (i->snapshot == k.k->p.snapshot) {
-                       snapshots_seen_exit(&i->seen);
-                       *i = n;
-                       return 0;
-               }
-
-               if (i->snapshot >= k.k->p.snapshot)
-                       break;
-       }
-
-       return darray_insert_item(&extent_ends->e, i - extent_ends->e.data, n);
-}
-
-static int overlapping_extents_found(struct btree_trans *trans,
-                                    enum btree_id btree,
-                                    struct bpos pos1, struct snapshots_seen *pos1_seen,
-                                    struct bkey pos2,
-                                    bool *fixed,
-                                    struct extent_end *extent_end)
-{
-       struct bch_fs *c = trans->c;
-       struct printbuf buf = PRINTBUF;
-       struct btree_iter iter1, iter2 = { NULL };
-       struct bkey_s_c k1, k2;
-       int ret;
-
-       BUG_ON(bkey_le(pos1, bkey_start_pos(&pos2)));
-
-       bch2_trans_iter_init(trans, &iter1, btree, pos1,
-                            BTREE_ITER_ALL_SNAPSHOTS|
-                            BTREE_ITER_NOT_EXTENTS);
-       k1 = bch2_btree_iter_peek_upto(&iter1, POS(pos1.inode, U64_MAX));
-       ret = bkey_err(k1);
-       if (ret)
-               goto err;
-
-       prt_str(&buf, "\n  ");
-       bch2_bkey_val_to_text(&buf, c, k1);
-
-       if (!bpos_eq(pos1, k1.k->p)) {
-               prt_str(&buf, "\n  wanted\n  ");
-               bch2_bpos_to_text(&buf, pos1);
-               prt_str(&buf, "\n  ");
-               bch2_bkey_to_text(&buf, &pos2);
-
-               bch_err(c, "%s: error finding first overlapping extent when repairing, got%s",
-                       __func__, buf.buf);
-               ret = -BCH_ERR_internal_fsck_err;
-               goto err;
-       }
-
-       bch2_trans_copy_iter(&iter2, &iter1);
-
-       while (1) {
-               bch2_btree_iter_advance(&iter2);
-
-               k2 = bch2_btree_iter_peek_upto(&iter2, POS(pos1.inode, U64_MAX));
-               ret = bkey_err(k2);
-               if (ret)
-                       goto err;
-
-               if (bpos_ge(k2.k->p, pos2.p))
-                       break;
-       }
-
-       prt_str(&buf, "\n  ");
-       bch2_bkey_val_to_text(&buf, c, k2);
-
-       if (bpos_gt(k2.k->p, pos2.p) ||
-           pos2.size != k2.k->size) {
-               bch_err(c, "%s: error finding seconding overlapping extent when repairing%s",
-                       __func__, buf.buf);
-               ret = -BCH_ERR_internal_fsck_err;
-               goto err;
-       }
-
-       prt_printf(&buf, "\n  overwriting %s extent",
-                  pos1.snapshot >= pos2.p.snapshot ? "first" : "second");
-
-       if (fsck_err(c, extent_overlapping,
-                    "overlapping extents%s", buf.buf)) {
-               struct btree_iter *old_iter = &iter1;
-               struct disk_reservation res = { 0 };
-
-               if (pos1.snapshot < pos2.p.snapshot) {
-                       old_iter = &iter2;
-                       swap(k1, k2);
-               }
-
-               trans->extra_disk_res += bch2_bkey_sectors_compressed(k2);
-
-               ret =   bch2_trans_update_extent_overwrite(trans, old_iter,
-                               BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE,
-                               k1, k2) ?:
-                       bch2_trans_commit(trans, &res, NULL, BCH_TRANS_COMMIT_no_enospc);
-               bch2_disk_reservation_put(c, &res);
-
-               if (ret)
-                       goto err;
-
-               *fixed = true;
-
-               if (pos1.snapshot == pos2.p.snapshot) {
-                       /*
-                        * We overwrote the first extent, and did the overwrite
-                        * in the same snapshot:
-                        */
-                       extent_end->offset = bkey_start_offset(&pos2);
-               } else if (pos1.snapshot > pos2.p.snapshot) {
-                       /*
-                        * We overwrote the first extent in pos2's snapshot:
-                        */
-                       ret = snapshots_seen_add_inorder(c, pos1_seen, pos2.p.snapshot);
-               } else {
-                       /*
-                        * We overwrote the second extent - restart
-                        * check_extent() from the top:
-                        */
-                       ret = -BCH_ERR_transaction_restart_nested;
-               }
-       }
-fsck_err:
-err:
-       bch2_trans_iter_exit(trans, &iter2);
-       bch2_trans_iter_exit(trans, &iter1);
-       printbuf_exit(&buf);
-       return ret;
-}
-
-static int check_overlapping_extents(struct btree_trans *trans,
-                             struct snapshots_seen *seen,
-                             struct extent_ends *extent_ends,
-                             struct bkey_s_c k,
-                             u32 equiv,
-                             struct btree_iter *iter,
-                             bool *fixed)
-{
-       struct bch_fs *c = trans->c;
-       int ret = 0;
-
-       /* transaction restart, running again */
-       if (bpos_eq(extent_ends->last_pos, k.k->p))
-               return 0;
-
-       if (extent_ends->last_pos.inode != k.k->p.inode)
-               extent_ends_reset(extent_ends);
-
-       darray_for_each(extent_ends->e, i) {
-               if (i->offset <= bkey_start_offset(k.k))
-                       continue;
-
-               if (!ref_visible2(c,
-                                 k.k->p.snapshot, seen,
-                                 i->snapshot, &i->seen))
-                       continue;
-
-               ret = overlapping_extents_found(trans, iter->btree_id,
-                                               SPOS(iter->pos.inode,
-                                                    i->offset,
-                                                    i->snapshot),
-                                               &i->seen,
-                                               *k.k, fixed, i);
-               if (ret)
-                       goto err;
-       }
-
-       ret = extent_ends_at(c, extent_ends, seen, k);
-       if (ret)
-               goto err;
-
-       extent_ends->last_pos = k.k->p;
-err:
-       return ret;
-}
-
-static int check_extent_overbig(struct btree_trans *trans, struct btree_iter *iter,
-                               struct bkey_s_c k)
-{
-       struct bch_fs *c = trans->c;
-       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-       struct bch_extent_crc_unpacked crc;
-       const union bch_extent_entry *i;
-       unsigned encoded_extent_max_sectors = c->opts.encoded_extent_max >> 9;
-
-       bkey_for_each_crc(k.k, ptrs, crc, i)
-               if (crc_is_encoded(crc) &&
-                   crc.uncompressed_size > encoded_extent_max_sectors) {
-                       struct printbuf buf = PRINTBUF;
-
-                       bch2_bkey_val_to_text(&buf, c, k);
-                       bch_err(c, "overbig encoded extent, please report this:\n  %s", buf.buf);
-                       printbuf_exit(&buf);
-               }
-
-       return 0;
-}
-
-static int check_extent(struct btree_trans *trans, struct btree_iter *iter,
-                       struct bkey_s_c k,
-                       struct inode_walker *inode,
-                       struct snapshots_seen *s,
-                       struct extent_ends *extent_ends)
-{
-       struct bch_fs *c = trans->c;
-       struct inode_walker_entry *i;
-       struct printbuf buf = PRINTBUF;
-       struct bpos equiv = k.k->p;
-       int ret = 0;
-
-       equiv.snapshot = bch2_snapshot_equiv(c, k.k->p.snapshot);
-
-       ret = check_key_has_snapshot(trans, iter, k);
-       if (ret) {
-               ret = ret < 0 ? ret : 0;
-               goto out;
-       }
-
-       if (inode->last_pos.inode != k.k->p.inode) {
-               ret = check_i_sectors(trans, inode);
-               if (ret)
-                       goto err;
-       }
-
-       i = walk_inode(trans, inode, equiv, k.k->type == KEY_TYPE_whiteout);
-       ret = PTR_ERR_OR_ZERO(i);
-       if (ret)
-               goto err;
-
-       ret = snapshots_seen_update(c, s, iter->btree_id, k.k->p);
-       if (ret)
-               goto err;
-
-       if (k.k->type != KEY_TYPE_whiteout) {
-               if (fsck_err_on(!i, c, extent_in_missing_inode,
-                               "extent in missing inode:\n  %s",
-                               (printbuf_reset(&buf),
-                                bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-                       goto delete;
-
-               if (fsck_err_on(i &&
-                               !S_ISREG(i->inode.bi_mode) &&
-                               !S_ISLNK(i->inode.bi_mode),
-                               c, extent_in_non_reg_inode,
-                               "extent in non regular inode mode %o:\n  %s",
-                               i->inode.bi_mode,
-                               (printbuf_reset(&buf),
-                                bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-                       goto delete;
-
-               ret = check_overlapping_extents(trans, s, extent_ends, k,
-                                               equiv.snapshot, iter,
-                                               &inode->recalculate_sums);
-               if (ret)
-                       goto err;
-       }
-
-       /*
-        * Check inodes in reverse order, from oldest snapshots to newest,
-        * starting from the inode that matches this extent's snapshot. If we
-        * didn't have one, iterate over all inodes:
-        */
-       if (!i)
-               i = inode->inodes.data + inode->inodes.nr - 1;
-
-       for (;
-            inode->inodes.data && i >= inode->inodes.data;
-            --i) {
-               if (i->snapshot > equiv.snapshot ||
-                   !key_visible_in_snapshot(c, s, i->snapshot, equiv.snapshot))
-                       continue;
-
-               if (k.k->type != KEY_TYPE_whiteout) {
-                       if (fsck_err_on(!(i->inode.bi_flags & BCH_INODE_i_size_dirty) &&
-                                       k.k->p.offset > round_up(i->inode.bi_size, block_bytes(c)) >> 9 &&
-                                       !bkey_extent_is_reservation(k),
-                                       c, extent_past_end_of_inode,
-                                       "extent type past end of inode %llu:%u, i_size %llu\n  %s",
-                                       i->inode.bi_inum, i->snapshot, i->inode.bi_size,
-                                       (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
-                               struct btree_iter iter2;
-
-                               bch2_trans_copy_iter(&iter2, iter);
-                               bch2_btree_iter_set_snapshot(&iter2, i->snapshot);
-                               ret =   bch2_btree_iter_traverse(&iter2) ?:
-                                       bch2_btree_delete_at(trans, &iter2,
-                                               BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-                               bch2_trans_iter_exit(trans, &iter2);
-                               if (ret)
-                                       goto err;
-
-                               iter->k.type = KEY_TYPE_whiteout;
-                       }
-
-                       if (bkey_extent_is_allocation(k.k))
-                               i->count += k.k->size;
-               }
-
-               i->seen_this_pos = true;
-       }
-out:
-err:
-fsck_err:
-       printbuf_exit(&buf);
-       bch_err_fn(c, ret);
-       return ret;
-delete:
-       ret = bch2_btree_delete_at(trans, iter, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-       goto out;
-}
-
-/*
- * Walk extents: verify that extents have a corresponding S_ISREG inode, and
- * that i_size an i_sectors are consistent
- */
-int bch2_check_extents(struct bch_fs *c)
-{
-       struct inode_walker w = inode_walker_init();
-       struct snapshots_seen s;
-       struct extent_ends extent_ends;
-       struct disk_reservation res = { 0 };
-
-       snapshots_seen_init(&s);
-       extent_ends_init(&extent_ends);
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_extents,
-                               POS(BCACHEFS_ROOT_INO, 0),
-                               BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
-                               &res, NULL,
-                               BCH_TRANS_COMMIT_no_enospc, ({
-                       bch2_disk_reservation_put(c, &res);
-                       check_extent(trans, &iter, k, &w, &s, &extent_ends) ?:
-                       check_extent_overbig(trans, &iter, k);
-               })) ?:
-               check_i_sectors(trans, &w));
-
-       bch2_disk_reservation_put(c, &res);
-       extent_ends_exit(&extent_ends);
-       inode_walker_exit(&w);
-       snapshots_seen_exit(&s);
-
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-int bch2_check_indirect_extents(struct bch_fs *c)
-{
-       struct disk_reservation res = { 0 };
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_reflink,
-                               POS_MIN,
-                               BTREE_ITER_PREFETCH, k,
-                               &res, NULL,
-                               BCH_TRANS_COMMIT_no_enospc, ({
-                       bch2_disk_reservation_put(c, &res);
-                       check_extent_overbig(trans, &iter, k);
-               })));
-
-       bch2_disk_reservation_put(c, &res);
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static int check_subdir_count(struct btree_trans *trans, struct inode_walker *w)
-{
-       struct bch_fs *c = trans->c;
-       u32 restart_count = trans->restart_count;
-       int ret = 0;
-       s64 count2;
-
-       darray_for_each(w->inodes, i) {
-               if (i->inode.bi_nlink == i->count)
-                       continue;
-
-               count2 = bch2_count_subdirs(trans, w->last_pos.inode, i->snapshot);
-               if (count2 < 0)
-                       return count2;
-
-               if (i->count != count2) {
-                       bch_err(c, "fsck counted subdirectories wrong: got %llu should be %llu",
-                               i->count, count2);
-                       i->count = count2;
-                       if (i->inode.bi_nlink == i->count)
-                               continue;
-               }
-
-               if (fsck_err_on(i->inode.bi_nlink != i->count,
-                               c, inode_dir_wrong_nlink,
-                               "directory %llu:%u with wrong i_nlink: got %u, should be %llu",
-                               w->last_pos.inode, i->snapshot, i->inode.bi_nlink, i->count)) {
-                       i->inode.bi_nlink = i->count;
-                       ret = fsck_write_inode(trans, &i->inode, i->snapshot);
-                       if (ret)
-                               break;
-               }
-       }
-fsck_err:
-       bch_err_fn(c, ret);
-       return ret ?: trans_was_restarted(trans, restart_count);
-}
-
-static int check_dirent_target(struct btree_trans *trans,
-                              struct btree_iter *iter,
-                              struct bkey_s_c_dirent d,
-                              struct bch_inode_unpacked *target,
-                              u32 target_snapshot)
-{
-       struct bch_fs *c = trans->c;
-       struct bkey_i_dirent *n;
-       struct printbuf buf = PRINTBUF;
-       struct btree_iter bp_iter = { NULL };
-       int ret = 0;
-
-       if (!target->bi_dir &&
-           !target->bi_dir_offset) {
-               target->bi_dir          = d.k->p.inode;
-               target->bi_dir_offset   = d.k->p.offset;
-
-               ret = __write_inode(trans, target, target_snapshot);
-               if (ret)
-                       goto err;
-       }
-
-       if (!inode_points_to_dirent(target, d)) {
-               struct bkey_s_c_dirent bp_dirent = dirent_get_by_pos(trans, &bp_iter,
-                                     SPOS(target->bi_dir, target->bi_dir_offset, target_snapshot));
-               ret = bkey_err(bp_dirent);
-               if (ret && !bch2_err_matches(ret, ENOENT))
-                       goto err;
-
-               bool backpointer_exists = !ret;
-               ret = 0;
-
-               bch2_bkey_val_to_text(&buf, c, d.s_c);
-               prt_newline(&buf);
-               if (backpointer_exists)
-                       bch2_bkey_val_to_text(&buf, c, bp_dirent.s_c);
-
-               if (fsck_err_on(S_ISDIR(target->bi_mode) && backpointer_exists,
-                               c, inode_dir_multiple_links,
-                               "directory %llu:%u with multiple links\n%s",
-                               target->bi_inum, target_snapshot, buf.buf)) {
-                       ret = __remove_dirent(trans, d.k->p);
-                       goto out;
-               }
-
-               /*
-                * hardlinked file with nlink 0:
-                * We're just adjusting nlink here so check_nlinks() will pick
-                * it up, it ignores inodes with nlink 0
-                */
-               if (fsck_err_on(backpointer_exists && !target->bi_nlink,
-                               c, inode_multiple_links_but_nlink_0,
-                               "inode %llu:%u type %s has multiple links but i_nlink 0\n%s",
-                               target->bi_inum, target_snapshot, bch2_d_types[d.v->d_type], buf.buf)) {
-                       target->bi_nlink++;
-                       target->bi_flags &= ~BCH_INODE_unlinked;
-
-                       ret = __write_inode(trans, target, target_snapshot);
-                       if (ret)
-                               goto err;
-               }
-
-               if (fsck_err_on(!backpointer_exists,
-                               c, inode_wrong_backpointer,
-                               "inode %llu:%u has wrong backpointer:\n"
-                               "got       %llu:%llu\n"
-                               "should be %llu:%llu",
-                               target->bi_inum, target_snapshot,
-                               target->bi_dir,
-                               target->bi_dir_offset,
-                               d.k->p.inode,
-                               d.k->p.offset)) {
-                       target->bi_dir          = d.k->p.inode;
-                       target->bi_dir_offset   = d.k->p.offset;
-
-                       ret = __write_inode(trans, target, target_snapshot);
-                       if (ret)
-                               goto err;
-               }
-       }
-
-       if (fsck_err_on(d.v->d_type != inode_d_type(target),
-                       c, dirent_d_type_wrong,
-                       "incorrect d_type: got %s, should be %s:\n%s",
-                       bch2_d_type_str(d.v->d_type),
-                       bch2_d_type_str(inode_d_type(target)),
-                       (printbuf_reset(&buf),
-                        bch2_bkey_val_to_text(&buf, c, d.s_c), buf.buf))) {
-               n = bch2_trans_kmalloc(trans, bkey_bytes(d.k));
-               ret = PTR_ERR_OR_ZERO(n);
-               if (ret)
-                       goto err;
-
-               bkey_reassemble(&n->k_i, d.s_c);
-               n->v.d_type = inode_d_type(target);
-
-               ret = bch2_trans_update(trans, iter, &n->k_i, 0);
-               if (ret)
-                       goto err;
-
-               d = dirent_i_to_s_c(n);
-       }
-
-       if (fsck_err_on(d.v->d_type == DT_SUBVOL &&
-                       target->bi_parent_subvol != le32_to_cpu(d.v->d_parent_subvol),
-                       c, dirent_d_parent_subvol_wrong,
-                       "dirent has wrong d_parent_subvol field: got %u, should be %u",
-                       le32_to_cpu(d.v->d_parent_subvol),
-                       target->bi_parent_subvol)) {
-               n = bch2_trans_kmalloc(trans, bkey_bytes(d.k));
-               ret = PTR_ERR_OR_ZERO(n);
-               if (ret)
-                       goto err;
-
-               bkey_reassemble(&n->k_i, d.s_c);
-               n->v.d_parent_subvol = cpu_to_le32(target->bi_parent_subvol);
-
-               ret = bch2_trans_update(trans, iter, &n->k_i, 0);
-               if (ret)
-                       goto err;
-
-               d = dirent_i_to_s_c(n);
-       }
-out:
-err:
-fsck_err:
-       bch2_trans_iter_exit(trans, &bp_iter);
-       printbuf_exit(&buf);
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
-                       struct bkey_s_c k,
-                       struct bch_hash_info *hash_info,
-                       struct inode_walker *dir,
-                       struct inode_walker *target,
-                       struct snapshots_seen *s)
-{
-       struct bch_fs *c = trans->c;
-       struct bkey_s_c_dirent d;
-       struct inode_walker_entry *i;
-       struct printbuf buf = PRINTBUF;
-       struct bpos equiv;
-       int ret = 0;
-
-       ret = check_key_has_snapshot(trans, iter, k);
-       if (ret) {
-               ret = ret < 0 ? ret : 0;
-               goto out;
-       }
-
-       equiv = k.k->p;
-       equiv.snapshot = bch2_snapshot_equiv(c, k.k->p.snapshot);
-
-       ret = snapshots_seen_update(c, s, iter->btree_id, k.k->p);
-       if (ret)
-               goto err;
-
-       if (k.k->type == KEY_TYPE_whiteout)
-               goto out;
-
-       if (dir->last_pos.inode != k.k->p.inode) {
-               ret = check_subdir_count(trans, dir);
-               if (ret)
-                       goto err;
-       }
-
-       BUG_ON(!btree_iter_path(trans, iter)->should_be_locked);
-
-       i = walk_inode(trans, dir, equiv, k.k->type == KEY_TYPE_whiteout);
-       ret = PTR_ERR_OR_ZERO(i);
-       if (ret < 0)
-               goto err;
-
-       if (dir->first_this_inode && dir->inodes.nr)
-               *hash_info = bch2_hash_info_init(c, &dir->inodes.data[0].inode);
-       dir->first_this_inode = false;
-
-       if (fsck_err_on(!i, c, dirent_in_missing_dir_inode,
-                       "dirent in nonexisting directory:\n%s",
-                       (printbuf_reset(&buf),
-                        bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
-               ret = bch2_btree_delete_at(trans, iter,
-                               BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
-               goto out;
-       }
-
-       if (!i)
-               goto out;
-
-       if (fsck_err_on(!S_ISDIR(i->inode.bi_mode),
-                       c, dirent_in_non_dir_inode,
-                       "dirent in non directory inode type %s:\n%s",
-                       bch2_d_type_str(inode_d_type(&i->inode)),
-                       (printbuf_reset(&buf),
-                        bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
-               ret = bch2_btree_delete_at(trans, iter, 0);
-               goto out;
-       }
-
-       ret = hash_check_key(trans, bch2_dirent_hash_desc, hash_info, iter, k);
-       if (ret < 0)
-               goto err;
-       if (ret) {
-               /* dirent has been deleted */
-               ret = 0;
-               goto out;
-       }
-
-       if (k.k->type != KEY_TYPE_dirent)
-               goto out;
-
-       d = bkey_s_c_to_dirent(k);
-
-       if (d.v->d_type == DT_SUBVOL) {
-               struct bch_inode_unpacked subvol_root;
-               u32 target_subvol = le32_to_cpu(d.v->d_child_subvol);
-               u32 target_snapshot;
-               u64 target_inum;
-
-               ret = subvol_lookup(trans, target_subvol,
-                                     &target_snapshot, &target_inum);
-               if (ret && !bch2_err_matches(ret, ENOENT))
-                       goto err;
-
-               if (fsck_err_on(ret, c, dirent_to_missing_subvol,
-                               "dirent points to missing subvolume %u",
-                               le32_to_cpu(d.v->d_child_subvol))) {
-                       ret = __remove_dirent(trans, d.k->p);
-                       goto err;
-               }
-
-               ret = lookup_inode(trans, target_inum,
-                                  &subvol_root, &target_snapshot);
-               if (ret && !bch2_err_matches(ret, ENOENT))
-                       goto err;
-
-               if (fsck_err_on(ret, c, subvol_to_missing_root,
-                               "subvolume %u points to missing subvolume root %llu",
-                               target_subvol,
-                               target_inum)) {
-                       bch_err(c, "repair not implemented yet");
-                       ret = -EINVAL;
-                       goto err;
-               }
-
-               if (fsck_err_on(subvol_root.bi_subvol != target_subvol,
-                               c, subvol_root_wrong_bi_subvol,
-                               "subvol root %llu has wrong bi_subvol field: got %u, should be %u",
-                               target_inum,
-                               subvol_root.bi_subvol, target_subvol)) {
-                       subvol_root.bi_subvol = target_subvol;
-                       ret = __write_inode(trans, &subvol_root, target_snapshot);
-                       if (ret)
-                               goto err;
-               }
-
-               ret = check_dirent_target(trans, iter, d, &subvol_root,
-                                         target_snapshot);
-               if (ret)
-                       goto err;
-       } else {
-               ret = __get_visible_inodes(trans, target, s, le64_to_cpu(d.v->d_inum));
-               if (ret)
-                       goto err;
-
-               if (fsck_err_on(!target->inodes.nr,
-                               c, dirent_to_missing_inode,
-                               "dirent points to missing inode: (equiv %u)\n%s",
-                               equiv.snapshot,
-                               (printbuf_reset(&buf),
-                                bch2_bkey_val_to_text(&buf, c, k),
-                                buf.buf))) {
-                       ret = __remove_dirent(trans, d.k->p);
-                       if (ret)
-                               goto err;
-               }
-
-               darray_for_each(target->inodes, i) {
-                       ret = check_dirent_target(trans, iter, d,
-                                                 &i->inode, i->snapshot);
-                       if (ret)
-                               goto err;
-               }
-       }
-
-       if (d.v->d_type == DT_DIR)
-               for_each_visible_inode(c, s, dir, equiv.snapshot, i)
-                       i->count++;
-
-out:
-err:
-fsck_err:
-       printbuf_exit(&buf);
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-/*
- * Walk dirents: verify that they all have a corresponding S_ISDIR inode,
- * validate d_type
- */
-int bch2_check_dirents(struct bch_fs *c)
-{
-       struct inode_walker dir = inode_walker_init();
-       struct inode_walker target = inode_walker_init();
-       struct snapshots_seen s;
-       struct bch_hash_info hash_info;
-
-       snapshots_seen_init(&s);
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_dirents,
-                               POS(BCACHEFS_ROOT_INO, 0),
-                               BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS,
-                               k,
-                               NULL, NULL,
-                               BCH_TRANS_COMMIT_no_enospc,
-                       check_dirent(trans, &iter, k, &hash_info, &dir, &target, &s)));
-
-       snapshots_seen_exit(&s);
-       inode_walker_exit(&dir);
-       inode_walker_exit(&target);
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static int check_xattr(struct btree_trans *trans, struct btree_iter *iter,
-                      struct bkey_s_c k,
-                      struct bch_hash_info *hash_info,
-                      struct inode_walker *inode)
-{
-       struct bch_fs *c = trans->c;
-       struct inode_walker_entry *i;
-       int ret;
-
-       ret = check_key_has_snapshot(trans, iter, k);
-       if (ret)
-               return ret;
-
-       i = walk_inode(trans, inode, k.k->p, k.k->type == KEY_TYPE_whiteout);
-       ret = PTR_ERR_OR_ZERO(i);
-       if (ret)
-               return ret;
-
-       if (inode->first_this_inode && inode->inodes.nr)
-               *hash_info = bch2_hash_info_init(c, &inode->inodes.data[0].inode);
-       inode->first_this_inode = false;
-
-       if (fsck_err_on(!i, c, xattr_in_missing_inode,
-                       "xattr for missing inode %llu",
-                       k.k->p.inode))
-               return bch2_btree_delete_at(trans, iter, 0);
-
-       if (!i)
-               return 0;
-
-       ret = hash_check_key(trans, bch2_xattr_hash_desc, hash_info, iter, k);
-fsck_err:
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-/*
- * Walk xattrs: verify that they all have a corresponding inode
- */
-int bch2_check_xattrs(struct bch_fs *c)
-{
-       struct inode_walker inode = inode_walker_init();
-       struct bch_hash_info hash_info;
-       int ret = 0;
-
-       ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_xattrs,
-                       POS(BCACHEFS_ROOT_INO, 0),
-                       BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS,
-                       k,
-                       NULL, NULL,
-                       BCH_TRANS_COMMIT_no_enospc,
-               check_xattr(trans, &iter, k, &hash_info, &inode)));
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static int check_root_trans(struct btree_trans *trans)
-{
-       struct bch_fs *c = trans->c;
-       struct bch_inode_unpacked root_inode;
-       u32 snapshot;
-       u64 inum;
-       int ret;
-
-       ret = subvol_lookup(trans, BCACHEFS_ROOT_SUBVOL, &snapshot, &inum);
-       if (ret && !bch2_err_matches(ret, ENOENT))
-               return ret;
-
-       if (mustfix_fsck_err_on(ret, c, root_subvol_missing,
-                               "root subvol missing")) {
-               struct bkey_i_subvolume root_subvol;
-
-               snapshot        = U32_MAX;
-               inum            = BCACHEFS_ROOT_INO;
-
-               bkey_subvolume_init(&root_subvol.k_i);
-               root_subvol.k.p.offset = BCACHEFS_ROOT_SUBVOL;
-               root_subvol.v.flags     = 0;
-               root_subvol.v.snapshot  = cpu_to_le32(snapshot);
-               root_subvol.v.inode     = cpu_to_le64(inum);
-               ret = bch2_btree_insert_trans(trans, BTREE_ID_subvolumes, &root_subvol.k_i, 0);
-               bch_err_msg(c, ret, "writing root subvol");
-               if (ret)
-                       goto err;
-       }
-
-       ret = lookup_inode(trans, BCACHEFS_ROOT_INO, &root_inode, &snapshot);
-       if (ret && !bch2_err_matches(ret, ENOENT))
-               return ret;
-
-       if (mustfix_fsck_err_on(ret, c, root_dir_missing,
-                               "root directory missing") ||
-           mustfix_fsck_err_on(!S_ISDIR(root_inode.bi_mode),
-                               c, root_inode_not_dir,
-                               "root inode not a directory")) {
-               bch2_inode_init(c, &root_inode, 0, 0, S_IFDIR|0755,
-                               0, NULL);
-               root_inode.bi_inum = inum;
-
-               ret = __write_inode(trans, &root_inode, snapshot);
-               bch_err_msg(c, ret, "writing root inode");
-       }
-err:
-fsck_err:
-       return ret;
-}
-
-/* Get root directory, create if it doesn't exist: */
-int bch2_check_root(struct bch_fs *c)
-{
-       int ret = bch2_trans_do(c, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
-               check_root_trans(trans));
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-struct pathbuf_entry {
-       u64     inum;
-       u32     snapshot;
-};
-
-typedef DARRAY(struct pathbuf_entry) pathbuf;
-
-static bool path_is_dup(pathbuf *p, u64 inum, u32 snapshot)
-{
-       darray_for_each(*p, i)
-               if (i->inum     == inum &&
-                   i->snapshot == snapshot)
-                       return true;
-       return false;
-}
-
-static int path_down(struct bch_fs *c, pathbuf *p,
-                    u64 inum, u32 snapshot)
-{
-       int ret = darray_push(p, ((struct pathbuf_entry) {
-               .inum           = inum,
-               .snapshot       = snapshot,
-       }));
-
-       if (ret)
-               bch_err(c, "fsck: error allocating memory for pathbuf, size %zu",
-                       p->size);
-       return ret;
-}
-
-/*
- * Check that a given inode is reachable from the root:
- *
- * XXX: we should also be verifying that inodes are in the right subvolumes
- */
-static int check_path(struct btree_trans *trans,
-                     pathbuf *p,
-                     struct bch_inode_unpacked *inode,
-                     u32 snapshot)
-{
-       struct bch_fs *c = trans->c;
-       int ret = 0;
-
-       snapshot = bch2_snapshot_equiv(c, snapshot);
-       p->nr = 0;
-
-       while (!(inode->bi_inum == BCACHEFS_ROOT_INO &&
-                inode->bi_subvol == BCACHEFS_ROOT_SUBVOL)) {
-               struct btree_iter dirent_iter;
-               struct bkey_s_c_dirent d;
-               u32 parent_snapshot = snapshot;
-
-               if (inode->bi_subvol) {
-                       u64 inum;
-
-                       ret = subvol_lookup(trans, inode->bi_parent_subvol,
-                                           &parent_snapshot, &inum);
-                       if (ret)
-                               break;
-               }
-
-               d = dirent_get_by_pos(trans, &dirent_iter,
-                                     SPOS(inode->bi_dir, inode->bi_dir_offset,
-                                          parent_snapshot));
-               ret = bkey_err(d.s_c);
-               if (ret && !bch2_err_matches(ret, ENOENT))
-                       break;
-
-               if (!ret && !dirent_points_to_inode(d, inode)) {
-                       bch2_trans_iter_exit(trans, &dirent_iter);
-                       ret = -BCH_ERR_ENOENT_dirent_doesnt_match_inode;
-               }
-
-               if (bch2_err_matches(ret, ENOENT)) {
-                       if (fsck_err(c,  inode_unreachable,
-                                    "unreachable inode %llu:%u, type %s nlink %u backptr %llu:%llu",
-                                    inode->bi_inum, snapshot,
-                                    bch2_d_type_str(inode_d_type(inode)),
-                                    inode->bi_nlink,
-                                    inode->bi_dir,
-                                    inode->bi_dir_offset))
-                               ret = reattach_inode(trans, inode, snapshot);
-                       break;
-               }
-
-               bch2_trans_iter_exit(trans, &dirent_iter);
-
-               if (!S_ISDIR(inode->bi_mode))
-                       break;
-
-               ret = path_down(c, p, inode->bi_inum, snapshot);
-               if (ret) {
-                       bch_err(c, "memory allocation failure");
-                       return ret;
-               }
-
-               snapshot = parent_snapshot;
-
-               ret = lookup_inode(trans, inode->bi_dir, inode, &snapshot);
-               if (ret) {
-                       /* Should have been caught in dirents pass */
-                       if (!bch2_err_matches(ret, BCH_ERR_transaction_restart))
-                               bch_err(c, "error looking up parent directory: %i", ret);
-                       break;
-               }
-
-               if (path_is_dup(p, inode->bi_inum, snapshot)) {
-                       /* XXX print path */
-                       bch_err(c, "directory structure loop");
-
-                       darray_for_each(*p, i)
-                               pr_err("%llu:%u", i->inum, i->snapshot);
-                       pr_err("%llu:%u", inode->bi_inum, snapshot);
-
-                       if (!fsck_err(c, dir_loop, "directory structure loop"))
-                               return 0;
-
-                       ret = remove_backpointer(trans, inode);
-                       if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
-                               bch_err_msg(c, ret, "removing dirent");
-                       if (ret)
-                               break;
-
-                       ret = reattach_inode(trans, inode, snapshot);
-                       if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))
-                               bch_err_msg(c, ret, "reattaching inode %llu", inode->bi_inum);
-                       break;
-               }
-       }
-fsck_err:
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-/*
- * Check for unreachable inodes, as well as loops in the directory structure:
- * After bch2_check_dirents(), if an inode backpointer doesn't exist that means it's
- * unreachable:
- */
-int bch2_check_directory_structure(struct bch_fs *c)
-{
-       struct bch_inode_unpacked u;
-       pathbuf path = { 0, };
-       int ret;
-
-       ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_inodes, POS_MIN,
-                                         BTREE_ITER_INTENT|
-                                         BTREE_ITER_PREFETCH|
-                                         BTREE_ITER_ALL_SNAPSHOTS, k,
-                                         NULL, NULL, BCH_TRANS_COMMIT_no_enospc, ({
-                       if (!bkey_is_inode(k.k))
-                               continue;
-
-                       BUG_ON(bch2_inode_unpack(k, &u));
-
-                       if (u.bi_flags & BCH_INODE_unlinked)
-                               continue;
-
-                       check_path(trans, &path, &u, iter.pos.snapshot);
-               })));
-       darray_exit(&path);
-
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-struct nlink_table {
-       size_t          nr;
-       size_t          size;
-
-       struct nlink {
-               u64     inum;
-               u32     snapshot;
-               u32     count;
-       }               *d;
-};
-
-static int add_nlink(struct bch_fs *c, struct nlink_table *t,
-                    u64 inum, u32 snapshot)
-{
-       if (t->nr == t->size) {
-               size_t new_size = max_t(size_t, 128UL, t->size * 2);
-               void *d = kvmalloc_array(new_size, sizeof(t->d[0]), GFP_KERNEL);
-
-               if (!d) {
-                       bch_err(c, "fsck: error allocating memory for nlink_table, size %zu",
-                               new_size);
-                       return -BCH_ERR_ENOMEM_fsck_add_nlink;
-               }
-
-               if (t->d)
-                       memcpy(d, t->d, t->size * sizeof(t->d[0]));
-               kvfree(t->d);
-
-               t->d = d;
-               t->size = new_size;
-       }
-
-
-       t->d[t->nr++] = (struct nlink) {
-               .inum           = inum,
-               .snapshot       = snapshot,
-       };
-
-       return 0;
-}
-
-static int nlink_cmp(const void *_l, const void *_r)
-{
-       const struct nlink *l = _l;
-       const struct nlink *r = _r;
-
-       return cmp_int(l->inum, r->inum);
-}
-
-static void inc_link(struct bch_fs *c, struct snapshots_seen *s,
-                    struct nlink_table *links,
-                    u64 range_start, u64 range_end, u64 inum, u32 snapshot)
-{
-       struct nlink *link, key = {
-               .inum = inum, .snapshot = U32_MAX,
-       };
-
-       if (inum < range_start || inum >= range_end)
-               return;
-
-       link = __inline_bsearch(&key, links->d, links->nr,
-                               sizeof(links->d[0]), nlink_cmp);
-       if (!link)
-               return;
-
-       while (link > links->d && link[0].inum == link[-1].inum)
-               --link;
-
-       for (; link < links->d + links->nr && link->inum == inum; link++)
-               if (ref_visible(c, s, snapshot, link->snapshot)) {
-                       link->count++;
-                       if (link->snapshot >= snapshot)
-                               break;
-               }
-}
-
-noinline_for_stack
-static int check_nlinks_find_hardlinks(struct bch_fs *c,
-                                      struct nlink_table *t,
-                                      u64 start, u64 *end)
-{
-       int ret = bch2_trans_run(c,
-               for_each_btree_key(trans, iter, BTREE_ID_inodes,
-                                  POS(0, start),
-                                  BTREE_ITER_INTENT|
-                                  BTREE_ITER_PREFETCH|
-                                  BTREE_ITER_ALL_SNAPSHOTS, k, ({
-                       if (!bkey_is_inode(k.k))
-                               continue;
-
-                       /* Should never fail, checked by bch2_inode_invalid: */
-                       struct bch_inode_unpacked u;
-                       BUG_ON(bch2_inode_unpack(k, &u));
-
-                       /*
-                        * Backpointer and directory structure checks are sufficient for
-                        * directories, since they can't have hardlinks:
-                        */
-                       if (S_ISDIR(u.bi_mode))
-                               continue;
-
-                       if (!u.bi_nlink)
-                               continue;
-
-                       ret = add_nlink(c, t, k.k->p.offset, k.k->p.snapshot);
-                       if (ret) {
-                               *end = k.k->p.offset;
-                               ret = 0;
-                               break;
-                       }
-                       0;
-               })));
-
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-noinline_for_stack
-static int check_nlinks_walk_dirents(struct bch_fs *c, struct nlink_table *links,
-                                    u64 range_start, u64 range_end)
-{
-       struct snapshots_seen s;
-
-       snapshots_seen_init(&s);
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key(trans, iter, BTREE_ID_dirents, POS_MIN,
-                                  BTREE_ITER_INTENT|
-                                  BTREE_ITER_PREFETCH|
-                                  BTREE_ITER_ALL_SNAPSHOTS, k, ({
-                       ret = snapshots_seen_update(c, &s, iter.btree_id, k.k->p);
-                       if (ret)
-                               break;
-
-                       if (k.k->type == KEY_TYPE_dirent) {
-                               struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
-
-                               if (d.v->d_type != DT_DIR &&
-                                   d.v->d_type != DT_SUBVOL)
-                                       inc_link(c, &s, links, range_start, range_end,
-                                                le64_to_cpu(d.v->d_inum),
-                                                bch2_snapshot_equiv(c, d.k->p.snapshot));
-                       }
-                       0;
-               })));
-
-       snapshots_seen_exit(&s);
-
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static int check_nlinks_update_inode(struct btree_trans *trans, struct btree_iter *iter,
-                                    struct bkey_s_c k,
-                                    struct nlink_table *links,
-                                    size_t *idx, u64 range_end)
-{
-       struct bch_fs *c = trans->c;
-       struct bch_inode_unpacked u;
-       struct nlink *link = &links->d[*idx];
-       int ret = 0;
-
-       if (k.k->p.offset >= range_end)
-               return 1;
-
-       if (!bkey_is_inode(k.k))
-               return 0;
-
-       BUG_ON(bch2_inode_unpack(k, &u));
-
-       if (S_ISDIR(u.bi_mode))
-               return 0;
-
-       if (!u.bi_nlink)
-               return 0;
-
-       while ((cmp_int(link->inum, k.k->p.offset) ?:
-               cmp_int(link->snapshot, k.k->p.snapshot)) < 0) {
-               BUG_ON(*idx == links->nr);
-               link = &links->d[++*idx];
-       }
-
-       if (fsck_err_on(bch2_inode_nlink_get(&u) != link->count,
-                       c, inode_wrong_nlink,
-                       "inode %llu type %s has wrong i_nlink (%u, should be %u)",
-                       u.bi_inum, bch2_d_types[mode_to_type(u.bi_mode)],
-                       bch2_inode_nlink_get(&u), link->count)) {
-               bch2_inode_nlink_set(&u, link->count);
-               ret = __write_inode(trans, &u, k.k->p.snapshot);
-       }
-fsck_err:
-       return ret;
-}
-
-noinline_for_stack
-static int check_nlinks_update_hardlinks(struct bch_fs *c,
-                              struct nlink_table *links,
-                              u64 range_start, u64 range_end)
-{
-       size_t idx = 0;
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter, BTREE_ID_inodes,
-                               POS(0, range_start),
-                               BTREE_ITER_INTENT|BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
-                               NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
-                       check_nlinks_update_inode(trans, &iter, k, links, &idx, range_end)));
-       if (ret < 0) {
-               bch_err(c, "error in fsck walking inodes: %s", bch2_err_str(ret));
-               return ret;
-       }
-
-       return 0;
-}
-
-int bch2_check_nlinks(struct bch_fs *c)
-{
-       struct nlink_table links = { 0 };
-       u64 this_iter_range_start, next_iter_range_start = 0;
-       int ret = 0;
-
-       do {
-               this_iter_range_start = next_iter_range_start;
-               next_iter_range_start = U64_MAX;
-
-               ret = check_nlinks_find_hardlinks(c, &links,
-                                                 this_iter_range_start,
-                                                 &next_iter_range_start);
-
-               ret = check_nlinks_walk_dirents(c, &links,
-                                         this_iter_range_start,
-                                         next_iter_range_start);
-               if (ret)
-                       break;
-
-               ret = check_nlinks_update_hardlinks(c, &links,
-                                        this_iter_range_start,
-                                        next_iter_range_start);
-               if (ret)
-                       break;
-
-               links.nr = 0;
-       } while (next_iter_range_start != U64_MAX);
-
-       kvfree(links.d);
-       bch_err_fn(c, ret);
-       return ret;
-}
-
-static int fix_reflink_p_key(struct btree_trans *trans, struct btree_iter *iter,
-                            struct bkey_s_c k)
-{
-       struct bkey_s_c_reflink_p p;
-       struct bkey_i_reflink_p *u;
-
-       if (k.k->type != KEY_TYPE_reflink_p)
-               return 0;
-
-       p = bkey_s_c_to_reflink_p(k);
-
-       if (!p.v->front_pad && !p.v->back_pad)
-               return 0;
-
-       u = bch2_trans_kmalloc(trans, sizeof(*u));
-       int ret = PTR_ERR_OR_ZERO(u);
-       if (ret)
-               return ret;
-
-       bkey_reassemble(&u->k_i, k);
-       u->v.front_pad  = 0;
-       u->v.back_pad   = 0;
-
-       return bch2_trans_update(trans, iter, &u->k_i, BTREE_TRIGGER_NORUN);
-}
-
-int bch2_fix_reflink_p(struct bch_fs *c)
-{
-       if (c->sb.version >= bcachefs_metadata_version_reflink_p_fix)
-               return 0;
-
-       int ret = bch2_trans_run(c,
-               for_each_btree_key_commit(trans, iter,
-                               BTREE_ID_extents, POS_MIN,
-                               BTREE_ITER_INTENT|BTREE_ITER_PREFETCH|
-                               BTREE_ITER_ALL_SNAPSHOTS, k,
-                               NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
-                       fix_reflink_p_key(trans, &iter, k)));
-       bch_err_fn(c, ret);
-       return ret;
-}