From: Lars Ellenberg <lars.ellenberg@linbit.com>
Date: Mon, 10 Nov 2014 16:21:13 +0000 (+0100)
Subject: drbd: merge_bvec_fn: properly remap bvm->bi_bdev
X-Git-Tag: v3.4.107~142
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a2288455adaf8c9e4c3a77166910bd3e9756ec51;p=thirdparty%2Fkernel%2Fstable.git

drbd: merge_bvec_fn: properly remap bvm->bi_bdev

commit 3b9d35d744bb5139f9fed57f38c019bb8c7d351c upstream.

This was not noticed for many years. Affects operation if
md raid is used a backing device for DRBD.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
[lizf: Backported to 3.4: s/device/mdev]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index be984e0736664..43da226583481 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1184,6 +1184,7 @@ int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct
 		struct request_queue * const b =
 			mdev->ldev->backing_bdev->bd_disk->queue;
 		if (b->merge_bvec_fn) {
+			bvm->bi_bdev = mdev->ldev->backing_bdev;
 			backing_limit = b->merge_bvec_fn(b, bvm, bvec);
 			limit = min(limit, backing_limit);
 		}