ubifs: Use a random number for cookies

Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index a806107..9be71b6 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -39,6 +39,7 @@
 #include <linux/security.h>
 #include <linux/xattr.h>
 #include <linux/fscrypto.h>
+#include <linux/random.h>
 #include "ubifs-media.h"
 
 /* Version of this UBIFS implementation */