ovl: update ctime when changing fileattr

Currently we keep size, mode and times of overlay inode
as the same as upper inode, so should update ctime when
changing file attribution as well.
Signed-off-by: NChengguang Xu <cgxu519@mykernel.net>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

@@ -573,6 +573,9 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
 		BUILD_BUG_ON(OVL_PROT_I_FLAGS_MASK & ~OVL_COPY_I_FLAGS_MASK);
 		flags |= inode->i_flags & OVL_PROT_I_FLAGS_MASK;
 		inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
+
+		/* Update ctime */
+		ovl_copyattr(ovl_inode_real(inode), inode);
 	}
 	ovl_drop_write(dentry);
 out: