# \[PATCH v1 02/54\] block: loop: comment on direct access to bvec table

- From: Ming Lei \<tom.leiming@gmail.com\>
- Date: 2016-12-27 16:09:48 
- List: linux-block
- Page: https://ratatoskr.run/linux-block/2016/12/4900980
- Thread: https://ratatoskr.run/linux-block/2016/12/4900980/t.md

```text
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 drivers/block/loop.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f347285c67ec..be1cc51815ac 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -485,6 +485,11 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
 	/* nomerge for loop request queue */
 	WARN_ON(cmd->rq->bio != cmd->rq->biotail);
 
+	/*
+	 * For multipage bvec support, it is safe to pass the bvec
+	 * table to iov iterator, because iov iter still uses bvec
+	 * iter helpers to travese bvec.
+	 */
 	bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
 	iov_iter_bvec(&iter, ITER_BVEC | rw, bvec,
 		      bio_segments(bio), blk_rq_bytes(cmd->rq));
-- 
2.7.4

```