Btrfs: prevent loops in the directory tree when creating snapshots

[linux-2.6-block.git] / fs / btrfs / root-tree.c

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index e9be3abcb368391dce1a78ccb8ede44431a03baa..dbe20d4c6ea4aba935d37b6a3fd283427661ffec 100644 (file)
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -300,6 +300,22 @@ int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
        return ret;
 }
 
+int btrfs_find_root_ref(struct btrfs_root *tree_root,
+                  struct btrfs_path *path,
+                  u64 root_id, u64 ref_id)
+{
+       struct btrfs_key key;
+       int ret;
+
+       key.objectid = root_id;
+       key.type = BTRFS_ROOT_REF_KEY;
+       key.offset = ref_id;
+
+       ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
+       return ret;
+}
+
+
 /*
  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
  * or BTRFS_ROOT_BACKREF_KEY.