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-rw-r--r--block/blk-cgroup.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index d33dd6be1d9c..f9b55614d67d 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -119,6 +119,8 @@ 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;
+ bool need_plug = false;
/* as long as there are pending bios, @blkg can't go away */
spin_lock_bh(&blkg->async_bio_lock);
@@ -126,8 +128,15 @@ static void blkg_async_bio_workfn(struct work_struct *work)
bio_list_init(&blkg->async_bios);
spin_unlock_bh(&blkg->async_bio_lock);
+ /* start plug only when bio_list contains at least 2 bios */
+ if (bios.head && bios.head->bi_next) {
+ need_plug = true;
+ blk_start_plug(&plug);
+ }
while ((bio = bio_list_pop(&bios)))
submit_bio(bio);
+ if (need_plug)
+ blk_finish_plug(&plug);
}
/**