From 6958f145459ca7ad9715024de97445addacb8510 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 3 Sep 2010 11:56:16 +0200 Subject: [PATCH] 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 Cc: Christoph Hellwig Cc: Nick Piggin Cc: Michael S. Tsirkin Cc: Jeremy Fitzhardinge Cc: Chris Wright Signed-off-by: Jens Axboe --- block/blk-barrier.c | 35 +++++++---------------------------- drivers/block/brd.c | 2 +- drivers/block/virtio_blk.c | 9 --------- drivers/block/xen-blkfront.c | 8 +++----- drivers/scsi/sd.c | 4 +--- include/linux/blkdev.h | 17 +---------------- 6 files changed, 13 insertions(+), 62 deletions(-) diff --git a/block/blk-barrier.c b/block/blk-barrier.c index f0faefca032f..c807e9ca3a68 100644 --- a/block/blk-barrier.c +++ b/block/blk-barrier.c @@ -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; } diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 1c7f63792ff8..47a41272d26b 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -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); diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 2aafafca2b13..79652809eee8 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -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 diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index ac1b682edecb..50ec6f834996 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -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; diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 2714becc2eaf..cdfc51ab9cf2 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -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 diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 015375c7d031..7077bc0d6138 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -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 */ -- 2.20.1