rbd_dev->opts is not available for parent images, making checking rbd_dev->opts->read_only in various places (rbd_dev_image_probe(), need_exclusive_lock(), use_object_map() in the following patches) harder than it needs to be. Keeping rbd_dev_image_probe() in mind, move the initialization in do_rbd_add() up. snap_id isn't filled in at that point, so replace rbd_is_snap() with a snap_name comparison. Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Jason Dillaman <dillaman@redhat.com> Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>