--- zzzz-none-000/linux-4.4.60/fs/open.c	2017-04-08 07:53:53.000000000 +0000
+++ dragonfly-4020-701/linux-4.4.60/fs/open.c	2018-11-08 13:36:17.000000000 +0000
@@ -673,7 +673,9 @@
 {
 	/* NB: we're sure to have correct a_ops only after f_op->open */
 	if (f->f_flags & O_DIRECT) {
+#ifdef CONFIG_DIRECT_IO
 		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
+#endif
 			return -EINVAL;
 	}
 	return 0;