From: Mingming Gu <mmgu@volanscomputer.com>
To: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: "Christian A . Ehrhardt" <lk@c--e.de>,
Jens Axboe <axboe@kernel.dk>,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Mingming Gu <mmgu@volanscomputer.com>
Subject: [PATCH] block: fix bio_copy_user_iov() for SG_DXFER_TO_FROM_DEV case
Date: Sat, 13 Apr 2024 11:45:08 +0800 [thread overview]
Message-ID: <1712979908-6132-1-git-send-email-mmgu@volanscomputer.com> (raw)
Commit "block: Fix WARNING in _copy_from_iter" is insufficient to make
SG_IO ioctl with a transfer direction of SG_DXFER_TO_FROM_DEV work;
the passed in iterator should be advanced after bio_copy_from_iter().
Otherwise its caller, blk_rq_map_user_iov(), will return -EINVAL due
to a wrong loop condition.
Instead of using a copy of the passed iterator, save iter->data_source
and restore it after bio_copy_from_iter().
Signed-off-by: Mingming Gu <mmgu@volanscomputer.com>
---
block/blk-map.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/block/blk-map.c b/block/blk-map.c
index 71210cd..eca02d9 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -211,11 +211,12 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
if (ret)
goto cleanup;
} else if (map_data && map_data->from_user) {
- struct iov_iter iter2 = *iter;
+ bool tmp = iter->data_source;
/* This is the copy-in part of SG_DXFER_TO_FROM_DEV. */
- iter2.data_source = ITER_SOURCE;
- ret = bio_copy_from_iter(bio, &iter2);
+ iter->data_source = ITER_SOURCE;
+ ret = bio_copy_from_iter(bio, iter);
+ iter->data_source = tmp;
if (ret)
goto cleanup;
} else {
--
2.7.4
reply other threads:[~2024-04-13 3:46 UTC|newest]
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