Patch "md: multipath: don't hardcopy bio in .make_request path" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
md-multipath-don-t-hardcopy-bio-in-.make_request-path.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ming Lei <[email protected]>
Date: Sat, 12 Mar 2016 09:29:40 +0800
Subject: md: multipath: don't hardcopy bio in .make_request path

From: Ming Lei <[email protected]>

commit fafcde3ac1a418688a734365203a12483b83907a upstream.

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.

---
 drivers/md/multipath.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -131,7 +131,9 @@ static void multipath_make_request(struc
 	}
 	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;

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/md-multipath-don-t-hardcopy-bio-in-.make_request-path.patch