On Mon, Jun 01, 2020 at 03:37:09PM +0300, Konstantin Khlebnikov wrote: > Add flag for marking bio-based queues which support REQ_NOWAIT. > Set for all request based (mq) devices. > > Stacking device should set it after blk_set_stacking_limits() if method > make_request() itself doesn't delay requests or handles REQ_NOWAIT.
I don't think this belongs into the queue limits. For example a stacking driver that always defers requests to a workqueue can support REQ_NOWAIT entirely independent of the underlying devices. I think this just needs to be a simple queue flag.
