[PATCH 3.4 036/176] drbd: merge_bvec_fn: properly remap bvm->bi_bdev

[lizf]

From: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>

3.4.107-rc1 review patch.  If anyone has any objections, please let me know.

------------------


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@xxxxxxxxxx>
Signed-off-by: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
[lizf: Backported to 3.4: s/device/mdev]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 drivers/block/drbd/drbd_req.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index be984e0..43da226 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);
 		}
-- 
1.9.1

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