[PATCHv2] nvme: only use power of two io boundaries

[Keith Busch]

On Fri, Aug 28, 2020 at 04:30:02AM +0000, Damien Le Moal wrote:
> On 2020/08/28 13:16, Keith Busch wrote:
> > As long as zone sizes reuse the queue's chunk_sectors, the zone size
> > needs to take precedence since it's more than just a hint compared to
> > NOIOB. If people complain about the warning, that may indicate we ought
> > to find a way to get around overloading the chunk_sectors queue limit,
> > but I suspect ZNS drives won't report an iob value.
> 
> Understood. But for ZNS, since the zone size would take precedence over iob for
> chunk sectors, wouldn't it make sense to have the entire code block under a
> if (!blk_queue_is_zoned(ns->queue)) ? Something like this:
> 
> 	if (!blk_queue_is_zoned(ns->queue)) {
> 		if (is_power_of_2(iob))
> 			blk_queue_chunk_sectors(ns->queue, iob);
> 		else if (iob && !(disk->flags & GENHD_FL_UP))
> 			dev_warn(ctrl->device,
> 				"namespace:%u has unused io boundary:%u\n",
> 				ns->head->ns_id, iob);
> 	}

Oh, I see. I think we should have the warning for ZNS too, though, just
to get an indication that devices really want this kind of
consideration.