[PATCH] blkcg: add plugging support for punt bio

[Xianting Tian]

Try to merge continuous bio to current task's plug fisrt.

Signed-off-by: Xianting Tian <xianting_tian@xxxxxxx>
---
 block/blk-cgroup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 0ecc897..fe5d361 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -122,6 +122,7 @@ static void blkg_async_bio_workfn(struct work_struct *work)
 					     async_bio_work);
 	struct bio_list bios = BIO_EMPTY_LIST;
 	struct bio *bio;
+	struct blk_plug plug;
 
 	/* as long as there are pending bios, @blkg can't go away */
 	spin_lock_bh(&blkg->async_bio_lock);
@@ -129,8 +130,10 @@ static void blkg_async_bio_workfn(struct work_struct *work)
 	bio_list_init(&blkg->async_bios);
 	spin_unlock_bh(&blkg->async_bio_lock);
 
+	blk_start_plug(&plug);
 	while ((bio = bio_list_pop(&bios)))
 		submit_bio(bio);
+	blk_finish_plug(&plug);
 }
 
 /**
-- 
1.8.3.1