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 <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
vieko · Dec 14, 2012 · 0cfbcaf · 0cfbcaf
1 parent 8dd2cb7
commit 0cfbcaf
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/block/blk-lib.c b/block/blk-lib.c
@@ -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))