Commit c1075e54 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

blk-mq: reflow blk_insert_flush 



Use a switch statement to decide on the disposition of a flush request
instead of multiple if statements, out of which one does checks that are
more complex than required.  Also warn on a malformed request early
on instead of doing a BUG_ON later.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230519044050.107790-3-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0b573692

block/blk-flush.c

+26 −27
Original line number Diff line number Diff line
@@ -402,6 +402,9 @@ void blk_insert_flush(struct request *rq) 
	struct blk_flush_queue *fq = blk_get_flush_queue(q, rq->mq_ctx);

	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;



	/* FLUSH/FUA request must never be merged */

	WARN_ON_ONCE(rq->bio != rq->biotail);



	/*

	 * @policy now records what operations need to be done.  Adjust

	 * REQ_PREFLUSH and FUA for the driver.
@@ -417,40 +420,36 @@ void blk_insert_flush(struct request *rq) 
	 */

	rq->cmd_flags |= REQ_SYNC;



	switch (policy) {

	case 0:

		/*

		 * An empty flush handed down from a stacking driver may

		 * translate into nothing if the underlying device does not

		 * advertise a write-back cache.  In this case, simply

		 * complete the request.

		 */

	if (!policy) {

		blk_mq_end_request(rq, 0);

		return;

	}



	BUG_ON(rq->bio != rq->biotail); /*assumes zero or single bio rq */



	case REQ_FSEQ_DATA:

		/*

	 * If there's data but flush is not necessary, the request can be

	 * processed directly without going through flush machinery.  Queue

	 * for normal execution.

		 * If there's data, but no flush is necessary, the request can

		 * be processed directly without going through flush machinery.

		 * Queue for normal execution.

		 */

	if ((policy & REQ_FSEQ_DATA) &&

	    !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {

		blk_mq_request_bypass_insert(rq, 0);

		blk_mq_run_hw_queue(hctx, false);

		return;

	}



	default:

		/*

	 * @rq should go through flush machinery.  Mark it part of flush

	 * sequence and submit for further processing.

		 * Mark the request as part of a flush sequence and submit it

		 * for further processing to the flush state machine.

		 */

		blk_rq_init_flush(rq);

		spin_lock_irq(&fq->mq_flush_lock);

		blk_flush_complete_seq(rq, fq, REQ_FSEQ_ACTIONS & ~policy, 0);

		spin_unlock_irq(&fq->mq_flush_lock);

	}

}



/**

 * blkdev_issue_flush - queue a flush