expandable RAID-Z

*** 314,323 ****
--- 314,324 ----
          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 */
  };
  
  /*