diff --git a/include/linux/fs.h b/include/linux/fs.h
index adce6e1..186da81 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -120,6 +120,7 @@
 #define MS_PRIVATE	(1<<18)	/* change to private */
 #define MS_SLAVE	(1<<19)	/* change to slave */
 #define MS_SHARED	(1<<20)	/* change to shared */
+#define MS_RELATIME	(1<<21)	/* Update atime relative to mtime/ctime. */
 #define MS_ACTIVE	(1<<30)
 #define MS_NOUSER	(1<<31)
 
diff --git a/include/linux/mount.h b/include/linux/mount.h
index e357dc8..1b7e178 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -27,6 +27,7 @@
 #define MNT_NOEXEC	0x04
 #define MNT_NOATIME	0x08
 #define MNT_NODIRATIME	0x10
+#define MNT_RELATIME	0x20
 
 #define MNT_SHRINKABLE	0x100