Commit fafcde3a authored Mar 12, 2016 by Ming Lei Committed by Shaohua Li Mar 14, 2016

md: multipath: don't hardcopy bio in .make_request path



Inside multipath_make_request(), multipath maps the incoming
bio into low level device's bio, but it is totally wrong to
copy the bio into mapped bio via '*mapped_bio = *bio'. For
example, .__bi_remaining is kept in the copy, especially if
the incoming bio is chained to via bio splitting, so .bi_end_io
can't be called for the mapped bio at all in the completing path
in this kind of situation.

This patch fixes the issue by using clone style.

Cc: stable@vger.kernel.org (v3.14+)
Reported-and-tested-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Shaohua Li <shli@fb.com>

parent fb3229d5

drivers/md/multipath.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -129,7 +129,9 @@ static void multipath_make_request(struct mddev mddev, struct bio bio)
		}
		multipath = conf->multipaths + mp_bh->path;

		mp_bh->bio = *bio;
		bio_init(&mp_bh->bio);
		__bio_clone_fast(&mp_bh->bio, bio);

		mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
		mp_bh->bio.bi_bdev = multipath->rdev->bdev;
		mp_bh->bio.bi_rw \|= REQ_FAILFAST_TRANSPORT;

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