Btrfs: support root level changes in __resolve_indirect_ref

With the tree mod log, we can have a tree that's two levels high, but
btrfs_search_old_slot may still return a path with the tree root at level
one instead. __resolve_indirect_ref must care for this and accept parents in
a lower level than expected.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 7301cdb4b2cb..cf0df904347f 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -301,10 +301,14 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
                 goto out;
 
         eb = path->nodes[level];
-        if (!eb) {
-                WARN_ON(1);
-                ret = 1;
-                goto out;
+        while (!eb) {
+                if (!level) {
+                        WARN_ON(1);
+                        ret = 1;
+                        goto out;
+                }
+                level--;
+                eb = path->nodes[level];
         }
 
         ret = add_all_parents(root, path, parents, level, &ref->key_for_search,