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Message-Id: <20170626121034.3051-3-ming.lei@redhat.com>
Date: Mon, 26 Jun 2017 20:09:45 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Jens Axboe <axboe@...com>, Christoph Hellwig <hch@...radead.org>,
Huang Ying <ying.huang@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Alexander Viro <viro@...iv.linux.org.uk>
Cc: linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
Ming Lei <ming.lei@...hat.com>
Subject: [PATCH v2 02/51] block: loop: comment on direct access to bvec table
Signed-off-by: Ming Lei <ming.lei@...hat.com>
---
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
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