block: improve flush bio completion (143a87f4) · Commits · 戴 / test

bio's for flush are completed twice - once during the data phase and one more time after the whole sequence is complete. The first completion shouldn't notify completion to the issuer. This was achieved by skipping all bio completion steps in req_bio_endio() for the first completion; however, this has two drawbacks. * Error is not recorded in bio and must be tracked somewhere else. * Partial completion is not supported. Both don't cause problems for the current users; however, they make further improvements difficult. Change req_bio_endio() such that it only skips the actual notification part for the first completion. bio completion is implemented with partial completions on mind anyway so this is as simple as moving the REQ_FLUSH_SEQ conditional such that only calling of bio_endio() is skipped. Signed-off-by:

Tejun Heo <tj@kernel.org> Signed-off-by:

Jens Axboe <jaxboe@fusionio.com>

block/blk-core.c

+21 −27

Original line number	Original line	Diff line number	Diff line
	@@ -136,7 +136,6 @@ static void req_bio_endio(struct request rq, struct bio bio,
	{		{
	struct request_queue *q = rq->q;		struct request_queue *q = rq->q;

	if (!(rq->cmd_flags & REQ_FLUSH_SEQ)) {
	if (error)		if (error)
	clear_bit(BIO_UPTODATE, &bio->bi_flags);		clear_bit(BIO_UPTODATE, &bio->bi_flags);
	else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
	@@ -157,17 +156,12 @@ static void req_bio_endio(struct request rq, struct bio bio,
	if (bio_integrity(bio))		if (bio_integrity(bio))
	bio_integrity_advance(bio, nbytes);		bio_integrity_advance(bio, nbytes);

	if (bio->bi_size == 0)		/* don't actually finish bio if it's part of flush sequence */
			if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
	bio_endio(bio, error);		bio_endio(bio, error);
	} else {		else if (error && !q->flush_err)
	/*
	* Okay, this is the sequenced flush request in
	* progress, just record the error;
	*/
	if (error && !q->flush_err)
	q->flush_err = error;		q->flush_err = error;
	}		}
	}

	void blk_dump_rq_flags(struct request rq, char msg)		void blk_dump_rq_flags(struct request rq, char msg)
	{		{

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