[PATCH] dm io: fix comments to align with on-stack plugging

[Xianting Tian <xianting_tian@126.com>]

From: Xianting Tian <xianting.tian@linux.alibaba.com>

Ther is no unplugging timer now, on-stack io plugging is used:
	struct blk_plug plug;

	blk_start_plug(&plug);
	submit_batch_of_io();
	blk_finish_plug(&plug);

So remove the old comments for unplugging timer.

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
 drivers/md/dm-io.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 2d3cda0..7dba193 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -528,11 +528,6 @@ static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
 
 /*
  * New collapsed (a)synchronous interface.
- *
- * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
- * the queue with blk_unplug() some time later or set REQ_SYNC in
- * io_req->bi_opf. If you fail to do one of these, the IO will be submitted to
- * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
  */
 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
 	  struct dm_io_region *where, unsigned long *sync_error_bits)
-- 
1.8.3.1