blk-flush: fix invalid BUG_ON in blk_insert_flush
A user reported a regression due to commit
4853abaae7e4a2af938115ce9071ef8684fb7af4 (block: fix flush
machinery for stacking drivers with differring flush flags).
Part of the problem is that blk_insert_flush required a
single bio be attached to the request. In reality, having
no attached bio is also a valid case, as can be observed with
an empty flush.
[1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html
Reported-by: Christophe Saout <christophe@saout.de>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com
Acked-by: Tejun Heo <tj@kernel.org>
Stable note: 3.1
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 491eb30..89ae3b9 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -320,7 +320,7 @@
return;
}
- BUG_ON(!rq->bio || rq->bio != rq->biotail);
+ BUG_ON(rq->bio != rq->biotail); /*assumes zero or single bio rq */
/*
* If there's data but flush is not necessary, the request can be