[PATCHv2] nvme: skip noiob for zoned devices

[Christoph Hellwig]

On Mon, Aug 10, 2020 at 07:56:22AM -0700, Keith Busch wrote:
> On Mon, Aug 10, 2020 at 02:33:13PM +0200, Christoph Hellwig wrote:
> > On Fri, Aug 07, 2020 at 09:32:35AM -0700, Keith Busch wrote:
> > > Zoned block devices reuse the chunk_sectors queue limit to define zone
> > > boundaries. If a such a device happens to also report an optimal
> > > boundary, do not use that to define the chunk_sectors as that may
> > > intermittently interfere with io splitting and zone size queries.
> > 
> > Instead of skipping shouldn't we use the max of noiob and the zone
> > size, even if that is mostly theoretical?
> 
> No, I don't think so. If noiob is larger, we'll return the wrong value
> for blk_queue_zone_sectors() and blkdev_nr_zones(), which will have
> undesirable consequences.

Then we at least need to warn about a larger noiob.  And add a
comment that we are ignoring it deliberately.