expandable RAID-Z

@@ -314,10 +314,11 @@
         vdev_file_probe,
         vdev_default_asize,
         vdev_file_io_start,
         vdev_file_io_done,
         NULL,
+        NULL,
         VDEV_TYPE_FILE,         /* name of this vdev type */
         B_TRUE                  /* leaf vdev */
 };
 
 /*