block: add plug for blkdev_issue_discard

Last post of this patch appears lost, so I resend this.

Now discard merge works, add plug for blkdev_issue_discard. This will help
discard request merge especially for raid0 case. In raid0, a big discard
request is split to small requests, and if correct plug is added, such small
requests can be merged in low layer.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Shaohua Li 2012-12-14 11:15:51 +08:00 committed by Jens Axboe
parent 8dd2cb7e88
commit 0cfbcafcae

View File

@ -48,6 +48,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
struct bio_batch bb;
struct bio *bio;
int ret = 0;
struct blk_plug plug;
if (!q)
return -ENXIO;
@ -82,6 +83,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
bb.flags = 1 << BIO_UPTODATE;
bb.wait = &wait;
blk_start_plug(&plug);
while (nr_sects) {
unsigned int req_sects;
sector_t end_sect, tmp;
@ -120,6 +122,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
atomic_inc(&bb.done);
submit_bio(type, bio);
}
blk_finish_plug(&plug);
/* Wait for bios in-flight */
if (!atomic_dec_and_test(&bb.done))