diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index e663ca0..70454f2 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * background writeback - scan btree for dirty data and write it to the backing
  * device