Allow elevators to sort/merge discard requests

But blkdev_issue_discard() still emits requests which are interpreted as
soft barriers, because naïve callers might otherwise issue subsequent
writes to those same sectors, which might cross on the queue (if they're
reallocated quickly enough).

Callers still _can_ issue non-barrier discard requests, but they have to
take care of queue ordering for themselves.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/block/ioctl.c b/block/ioctl.c
index 342298bb6080..375c57922b00 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -161,7 +161,7 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
                         bio->bi_size = len << 9;
                         len = 0;
                 }
-                submit_bio(WRITE_DISCARD, bio);
+                submit_bio(DISCARD_NOBARRIER, bio);
 
                 wait_for_completion(&wait);