Btrfs: remove unused variable in the iterate_extent_inodes()

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 8623c74..23e927b 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1464,8 +1464,6 @@
 				iterate_extent_inodes_t *iterate, void *ctx)
 {
 	int ret;
-	struct list_head data_refs = LIST_HEAD_INIT(data_refs);
-	struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
 	struct btrfs_trans_handle *trans;
 	struct ulist *refs = NULL;
 	struct ulist *roots = NULL;