diff --git a/[refs] b/[refs]
index 89cfec78aaef..55f66295564f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3151527ee007b73a0ebd296010f1c0454a919c7d
+refs/heads/master: 90563b198e4c6674c63672fae1923da467215f45
diff --git a/trunk/fs/namespace.c b/trunk/fs/namespace.c
index a3035223d421..8505b5ece5de 100644
--- a/trunk/fs/namespace.c
+++ b/trunk/fs/namespace.c
@@ -1713,6 +1713,9 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
 	if (readonly_request == __mnt_is_readonly(mnt))
 		return 0;
 
+	if (mnt->mnt_flags & MNT_LOCK_READONLY)
+		return -EPERM;
+
 	if (readonly_request)
 		error = mnt_make_readonly(real_mount(mnt));
 	else
diff --git a/trunk/include/linux/mount.h b/trunk/include/linux/mount.h
index d7029f4a191a..73005f9957ea 100644
--- a/trunk/include/linux/mount.h
+++ b/trunk/include/linux/mount.h
@@ -47,6 +47,8 @@ struct mnt_namespace;
 
 #define MNT_INTERNAL	0x4000
 
+#define MNT_LOCK_READONLY	0x400000
+
 struct vfsmount {
 	struct dentry *mnt_root;	/* root of the mounted tree */
 	struct super_block *mnt_sb;	/* pointer to superblock */