[PATCH v2 02/51] block: loop: comment on direct access to bvec table

Ming Lei
2017-06-26T12:12:02Z

drivers/block/loop.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 0de11444e317..88063ab17e9a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -487,6 +487,11 @@ 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));
--
2.9.4