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: Tejun 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: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Tejun Heo
2010-09-03 11:56:16 +02:00
committed by Jens Axboe
parent 589d7ed02a
commit 6958f14545
6 changed files with 13 additions and 62 deletions
-9
View File
@@ -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