Commit 6958f145 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: kill QUEUE_ORDERED_BY_TAG 



Nobody is making meaningful use of ORDERED_BY_TAG now and queue
draining for barrier requests will be removed soon which will render
the advantage of tag ordering moot.  Kill ORDERED_BY_TAG.  The
following users are affected.

* brd: converted to ORDERED_DRAIN.
* virtio_blk: ORDERED_TAG path was already marked deprecated.  Removed.
* xen-blkfront: ORDERED_TAG case dropped.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 589d7ed0

block/blk-barrier.c

+7 −28
Original line number Diff line number Diff line
@@ -26,10 +26,7 @@ int blk_queue_ordered(struct request_queue *q, unsigned ordered) 
	if (ordered != QUEUE_ORDERED_NONE &&

	    ordered != QUEUE_ORDERED_DRAIN &&

	    ordered != QUEUE_ORDERED_DRAIN_FLUSH &&

	    ordered != QUEUE_ORDERED_DRAIN_FUA &&

	    ordered != QUEUE_ORDERED_TAG &&

	    ordered != QUEUE_ORDERED_TAG_FLUSH &&

	    ordered != QUEUE_ORDERED_TAG_FUA) {

	    ordered != QUEUE_ORDERED_DRAIN_FUA) {

		printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);

		return -EINVAL;

	}
@@ -155,21 +152,9 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp) 
	 * For an empty barrier, there's no actual BAR request, which

	 * in turn makes POSTFLUSH unnecessary.  Mask them off.

	 */

	if (!blk_rq_sectors(rq)) {

	if (!blk_rq_sectors(rq))

		q->ordered &= ~(QUEUE_ORDERED_DO_BAR |

				QUEUE_ORDERED_DO_POSTFLUSH);

		/*

		 * Empty barrier on a write-through device w/ ordered

		 * tag has no command to issue and without any command

		 * to issue, ordering by tag can't be used.  Drain

		 * instead.

		 */

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

		    !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) {

			q->ordered &= ~QUEUE_ORDERED_BY_TAG;

			q->ordered |= QUEUE_ORDERED_BY_DRAIN;

		}

	}



	/* stash away the original request */

	blk_dequeue_request(rq);
@@ -210,7 +195,7 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp) 
	} else

		skip |= QUEUE_ORDSEQ_PREFLUSH;



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

	if (queue_in_flight(q))

		rq = NULL;

	else

		skip |= QUEUE_ORDSEQ_DRAIN;
@@ -257,16 +242,10 @@ bool blk_do_ordered(struct request_queue *q, struct request **rqp) 
	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)

		return true;



	if (q->ordered & QUEUE_ORDERED_BY_TAG) {

		/* Ordered by tag.  Blocking the next barrier is enough. */

		if (is_barrier && rq != &q->bar_rq)

			*rqp = NULL;

	} else {

	/* Ordered by draining.  Wait for turn. */

	WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));

	if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))

		*rqp = NULL;

	}



	return true;

}

drivers/block/brd.c

+1 −1
Original line number Diff line number Diff line
@@ -482,7 +482,7 @@ static struct brd_device *brd_alloc(int i) 
	if (!brd->brd_queue)

		goto out_free_dev;

	blk_queue_make_request(brd->brd_queue, brd_make_request);

	blk_queue_ordered(brd->brd_queue, QUEUE_ORDERED_TAG);

	blk_queue_ordered(brd->brd_queue, QUEUE_ORDERED_DRAIN);

	blk_queue_max_hw_sectors(brd->brd_queue, 1024);

	blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);

drivers/block/virtio_blk.c

+0 −9
Original line number Diff line number Diff line
@@ -395,15 +395,6 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) 
		 * to implement write barrier support.

		 */

		blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH);

	} else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) {

		/*

		 * If the BARRIER feature is supported the host expects us

		 * to order request by tags.  This implies there is not

		 * volatile write cache on the host, and that the host

		 * never re-orders outstanding I/O.  This feature is not

		 * useful for real life scenarious and deprecated.

		 */

		blk_queue_ordered(q, QUEUE_ORDERED_TAG);

	} else {

		/*

		 * If the FLUSH feature is not supported we must assume that

drivers/block/xen-blkfront.c

+3 −5
Original line number Diff line number Diff line
@@ -424,8 +424,7 @@ static int xlvbd_barrier(struct blkfront_info *info) 
	const char *barrier;



	switch (info->feature_barrier) {

	case QUEUE_ORDERED_DRAIN:	barrier = "enabled (drain)"; break;

	case QUEUE_ORDERED_TAG:		barrier = "enabled (tag)"; break;

	case QUEUE_ORDERED_DRAIN:	barrier = "enabled"; break;

	case QUEUE_ORDERED_NONE:	barrier = "disabled"; break;

	default:			return -EINVAL;

	}
@@ -1078,8 +1077,7 @@ static void blkfront_connect(struct blkfront_info *info) 
	 * we're dealing with a very old backend which writes

	 * synchronously; draining will do what needs to get done.

	 *

	 * If there are barriers, then we can do full queued writes

	 * with tagged barriers.

	 * If there are barriers, then we use flush.

	 *

	 * If barriers are not supported, then there's no much we can

	 * do, so just set ordering to NONE.
@@ -1087,7 +1085,7 @@ static void blkfront_connect(struct blkfront_info *info) 
	if (err)

		info->feature_barrier = QUEUE_ORDERED_DRAIN;

	else if (barrier)

		info->feature_barrier = QUEUE_ORDERED_TAG;

		info->feature_barrier = QUEUE_ORDERED_DRAIN_FLUSH;

	else

		info->feature_barrier = QUEUE_ORDERED_NONE;

drivers/scsi/sd.c

+1 −3
Original line number Diff line number Diff line
@@ -2151,9 +2151,7 @@ static int sd_revalidate_disk(struct gendisk *disk) 


	/*

	 * We now have all cache related info, determine how we deal

	 * with ordered requests.  Note that as the current SCSI

	 * dispatch function can alter request order, we cannot use

	 * QUEUE_ORDERED_TAG_* even when ordered tag is supported.

	 * with ordered requests.

	 */

	if (sdkp->WCE)

		ordered = sdkp->DPOFUA

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