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fs: btrfs: do not fail when offset of a ROOT_ITEM is not -1

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When the btrfs_read_fs_root() function is searching a ROOT_ITEM with
location key offset other than -1, it currently fails via BUG_ON.

The offset can have other value than -1, though. This can happen for
example if a subvolume is renamed:

  $ btrfs subvolume create X && sync
  Create subvolume './X'
  $ btrfs inspect-internal dump-tree /dev/root | grep -B 2 'name: X$
        location key (270 ROOT_ITEM 18446744073709551615) type DIR
        transid 283 data_len 0 name_len 1
        name: X
  $ mv X Y && sync
  $ btrfs inspect-internal dump-tree /dev/root | grep -B 2 'name: Y$
        location key (270 ROOT_ITEM 0) type DIR
        transid 285 data_len 0 name_len 1
        name: Y

As can be seen the offset changed from -1ULL to 0.

Do not fail in this case.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Cc: David Sterba <dsterba@suse.com>
Cc: Qu Wenruo <wqu@suse.com>
Cc: Tom Rini <trini@konsulko.com>
This commit is contained in:
Marek Behún 2021-02-09 18:33:37 +01:00 committed by Tom Rini
parent 85ae52b959
commit 1afb9f2222
1 changed files with 1 additions and 2 deletions
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3
fs/btrfs/disk-io.c
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@ -732,8 +732,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
return fs_info->chunk_root;
if (location->objectid == BTRFS_CSUM_TREE_OBJECTID)
return fs_info->csum_root;
BUG_ON(location->objectid == BTRFS_TREE_RELOC_OBJECTID ||
location->offset != (u64)-1);
BUG_ON(location->objectid == BTRFS_TREE_RELOC_OBJECTID);
node = rb_search(&fs_info->fs_root_tree, (void *)&objectid,
btrfs_fs_roots_compare_objectids, NULL);