- * Post-submit callback. Used by the ZBD code. @success == true means
- * that the I/O operation has been queued or completed successfully.
+ * ZBD mode zbd_queue_io callback: called after engine->queue operation
+ * to advance a zone write pointer and eventually unlock the I/O zone.
+ * @q indicates the I/O queue status (busy, queued or completed).
+ * @success == true means that the I/O operation has been queued or
+ * completed successfully.