[dm-devel] [PATCH 1/6] block: Adjust elv_iosched_show to return "none" for bio-based DM

[Mike Snitzer]

Bio-based DM doesn't use an elevator (queue is !blk_queue_stackable()).

Longer-term DM will not allocate an elevator for bio-based DM.  But even
then there will be small potential for an elevator to be allocated for
a request-based DM table only to have a bio-based table be loaded in the
end.

Displaying "none" for bio-based DM will help avoid user confusion.

Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Cc: Jens Axboe <jens.axboe at oracle.com>
---
 block/elevator.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6-block/block/elevator.c
===================================================================
--- linux-2.6-block.orig/block/elevator.c
+++ linux-2.6-block/block/elevator.c
@@ -1097,7 +1097,7 @@ ssize_t elv_iosched_show(struct request_
 	struct elevator_type *__e;
 	int len = 0;
 
-	if (!q->elevator)
+	if (!q->elevator || !blk_queue_stackable(q))
 		return sprintf(name, "none\n");
 
 	elv = e->elevator_type;