mdv_load
msg->mdv_load = callback;
devfs_msg->mdv_load = load;
devfs_destroy_related_worker(msg->mdv_load);
node = (struct devfs_node *)msg->mdv_load;
devfs_make_alias_worker((struct devfs_alias *)msg->mdv_load);
devfs_destroy_alias_worker((struct devfs_alias *)msg->mdv_load);
devfs_scan_callback_worker((devfs_scan_t *)msg->mdv_load,
msg->mdv_load = dev;