From: Mikulas Patocka Set queue ordered mode. It doesn't really matter what we set here because we don't ever put any requests on the queue. But we need to set something other than QUEUE_ORDERED_NONE so that __generic_make_request passes barrier requests to us. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon --- drivers/md/dm.c | 1 + 1 file changed, 1 insertion(+) Index: linux-2.6.29/drivers/md/dm.c =================================================================== --- linux-2.6.29.orig/drivers/md/dm.c +++ linux-2.6.29/drivers/md/dm.c @@ -1112,6 +1112,7 @@ static struct mapped_device *alloc_dev(i md->queue->backing_dev_info.congested_fn = dm_any_congested; md->queue->backing_dev_info.congested_data = md; blk_queue_make_request(md->queue, dm_request); + blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN, NULL); blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); md->queue->unplug_fn = dm_unplug_all; blk_queue_merge_bvec(md->queue, dm_merge_bvec);