Commit 4ee5eaf4 ("block: add a queue flag for request stacking support") introduced the concept of "STACKABLE" and blk-mq devices fit the definition in that they establish q->request_fn. So establish QUEUE_FLAG_STACKABLE in QUEUE_FLAG_MQ_DEFAULT. While not strictly needed (DM _could_ just check for q->mq_ops to assume the device is request-based), request-based DM support for blk-mq devices benefits from the ability to consistently check for QUEUE_FLAG_STACKABLE before allowing a device to be stacked into a request-based DM table. Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- include/linux/blkdev.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e5f620c..5ff3f5c 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -516,6 +516,7 @@ struct request_queue { (1 << QUEUE_FLAG_ADD_RANDOM)) #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ + (1 << QUEUE_FLAG_STACKABLE) | \ (1 << QUEUE_FLAG_SAME_COMP)) static inline void queue_lockdep_assert_held(struct request_queue *q) -- 1.9.3 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel