Include <linux/completion.h> for completion user
diff --git a/drivers/block/block_ioctl.c b/drivers/block/block_ioctl.c
index e206157..60b2fb3c 100644
--- a/drivers/block/block_ioctl.c
+++ b/drivers/block/block_ioctl.c
@@ -27,6 +27,7 @@
 #include <linux/smp_lock.h>
 #include <linux/module.h>
 #include <linux/blk.h>
+#include <linux/completion.h>
 
 #include <linux/cdrom.h>