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block: kill QUEUE_ORDERED_BY_TAG

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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
block/blk-barrier.c
View File

@ -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;
}
/* 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;
}

2
drivers/block/brd.c
View File

@ -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);

9
drivers/block/virtio_blk.c
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

8
drivers/block/xen-blkfront.c
View File

@ -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;

4
drivers/scsi/sd.c
View File

@ -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

17
include/linux/blkdev.h
View File

@ -470,12 +470,7 @@ enum {
* DRAIN : ordering by draining is enough
* DRAIN_FLUSH : ordering by draining w/ pre and post flushes
* DRAIN_FUA : ordering by draining w/ pre flush and FUA write
* TAG : ordering by tag is enough
* TAG_FLUSH : ordering by tag w/ pre and post flushes
* TAG_FUA : ordering by tag w/ pre flush and FUA write
*/
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,
@ -483,8 +478,7 @@ enum {
QUEUE_ORDERED_NONE = 0x00,
QUEUE_ORDERED_DRAIN = QUEUE_ORDERED_BY_DRAIN |
QUEUE_ORDERED_DO_BAR,
QUEUE_ORDERED_DRAIN = QUEUE_ORDERED_DO_BAR,
QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
QUEUE_ORDERED_DO_PREFLUSH |
QUEUE_ORDERED_DO_POSTFLUSH,
@ -492,15 +486,6 @@ enum {
QUEUE_ORDERED_DO_PREFLUSH |
QUEUE_ORDERED_DO_FUA,
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,
QUEUE_ORDERED_TAG_FUA = QUEUE_ORDERED_TAG |
QUEUE_ORDERED_DO_PREFLUSH |
QUEUE_ORDERED_DO_FUA,
/*
* Ordered operation sequence
*/