blk_queue_unprep_rq - set an unprepare_request function for queue
void blk_queue_unprep_rq(struct request_queue * q, unprep_rq_fn * ufn);
It's possible for a queue to register an unprepare_request callback which is invoked before the request is finally completed. The goal of the function is to deallocate any data that was allocated in the prepare_request callback.
|January 2017||Kernel Hackers Manual 4.8.|