[PATCH v4 1/5] blk-mq: introduce blk_mq_set_request_complete

[Christoph Hellwig]

> +static inline void blk_mq_set_request_complete(struct request *rq)
> +{
> +	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
> +}

This function needs a detailed comment explaining the use case.
Otherwise we'll get lots of driver abuses.