Btrfs: fix backref walking race with tree deletions
When a subvolume is removed, we remove the root item from the root tree,
while the tree blocks and backrefs remain for a while. When backref walking
comes across one of those orphan tree blocks, it can find a backref for a
no longer existing root. This is all good, we only must tolerate
__resolve_indirect_ref returning an error and continue with the good refs
found.
Reported-by: Alex Lyakas <alex.btrfs@zadarastorage.com>
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 04edf69..bd605c8 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -352,11 +352,8 @@
err = __resolve_indirect_ref(fs_info, search_commit_root,
time_seq, ref, parents,
extent_item_pos);
- if (err) {
- if (ret == 0)
- ret = err;
+ if (err)
continue;
- }
/* we put the first parent into the ref at hand */
ULIST_ITER_INIT(&uiter);