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Commit f671620e authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: make every barrier action optional 



In all barrier sequences, the barrier write itself was always assumed
to be issued and thus didn't have corresponding control flag.  This
patch adds QUEUE_ORDERED_DO_BAR and unify action mask handling in
start_ordered() such that any barrier action can be skipped.

This patch doesn't introduce any visible behavior changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent a7384677

block/blk-barrier.c

+24 −17
Original line number Diff line number Diff line
@@ -158,19 +158,10 @@ static inline struct request *start_ordered(struct request_queue *q, 
	q->ordered = q->next_ordered;

	q->ordseq |= QUEUE_ORDSEQ_STARTED;



	/*

	 * Prep proxy barrier request.

	 */

	/* stash away the original request */

	elv_dequeue_request(q, rq);

	q->orig_bar_rq = rq;

	rq = &q->bar_rq;

	blk_rq_init(q, rq);

	if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)

		rq->cmd_flags |= REQ_RW;

	if (q->ordered & QUEUE_ORDERED_DO_FUA)

		rq->cmd_flags |= REQ_FUA;

	init_request_from_bio(rq, q->orig_bar_rq->bio);

	rq->end_io = bar_end_io;

	rq = NULL;



	/*

	 * Queue ordered sequence.  As we stack them at the head, we
@@ -181,12 +172,28 @@ static inline struct request *start_ordered(struct request_queue *q, 
	 * there will be no data written between the pre and post flush.

	 * Hence a single flush will suffice.

	 */

	if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) && !blk_empty_barrier(rq))

	if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) &&

	    !blk_empty_barrier(q->orig_bar_rq)) {

		queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);

	else

		rq = &q->post_flush_rq;

	} else

		q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;



	if (q->ordered & QUEUE_ORDERED_DO_BAR) {

		rq = &q->bar_rq;



		/* initialize proxy request and queue it */

		blk_rq_init(q, rq);

		if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)

			rq->cmd_flags |= REQ_RW;

		if (q->ordered & QUEUE_ORDERED_DO_FUA)

			rq->cmd_flags |= REQ_FUA;

		init_request_from_bio(rq, q->orig_bar_rq->bio);

		rq->end_io = bar_end_io;



		elv_insert(q, rq, ELEVATOR_INSERT_FRONT);

	} else

		q->ordseq |= QUEUE_ORDSEQ_BAR;



	if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) {

		queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH);
@@ -194,10 +201,10 @@ static inline struct request *start_ordered(struct request_queue *q, 
	} else

		q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;



	if ((q->ordered & QUEUE_ORDERED_BY_TAG) || q->in_flight == 0)

		q->ordseq |= QUEUE_ORDSEQ_DRAIN;

	else

	if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && q->in_flight)

		rq = NULL;

	else

		q->ordseq |= QUEUE_ORDSEQ_DRAIN;



	return rq;

}

include/linux/blkdev.h

+5 −2
Original line number Diff line number Diff line
@@ -526,12 +526,14 @@ enum { 
	QUEUE_ORDERED_BY_DRAIN		= 0x01,

	QUEUE_ORDERED_BY_TAG		= 0x02,

	QUEUE_ORDERED_DO_PREFLUSH	= 0x10,

	QUEUE_ORDERED_DO_BAR		= 0x20,

	QUEUE_ORDERED_DO_POSTFLUSH	= 0x40,

	QUEUE_ORDERED_DO_FUA		= 0x80,



	QUEUE_ORDERED_NONE		= 0x00,



	QUEUE_ORDERED_DRAIN		= QUEUE_ORDERED_BY_DRAIN,

	QUEUE_ORDERED_DRAIN		= QUEUE_ORDERED_BY_DRAIN |

					  QUEUE_ORDERED_DO_BAR,

	QUEUE_ORDERED_DRAIN_FLUSH	= QUEUE_ORDERED_DRAIN |

					  QUEUE_ORDERED_DO_PREFLUSH |

					  QUEUE_ORDERED_DO_POSTFLUSH,
@@ -539,7 +541,8 @@ enum { 
					  QUEUE_ORDERED_DO_PREFLUSH |

					  QUEUE_ORDERED_DO_FUA,



	QUEUE_ORDERED_TAG		= QUEUE_ORDERED_BY_TAG,

	QUEUE_ORDERED_TAG		= QUEUE_ORDERED_BY_TAG |

					  QUEUE_ORDERED_DO_BAR,

	QUEUE_ORDERED_TAG_FLUSH		= QUEUE_ORDERED_TAG |

					  QUEUE_ORDERED_DO_PREFLUSH |

					  QUEUE_ORDERED_DO_POSTFLUSH,