Re: [RFC v1] nvme: add cse, ds, ms, nsze and nuse to sysfs

[Sagi Grimberg]

> > > > > > Should this even be an nvme specific attribute? I thought we should have
> > > > > > blk-integrity.c report its 'tuple_size' attribute instead. That should
> > > > > > work as long as we're not dealing with extended metadata at least, but
> > > > > > that's kind of a special format that doesn't have block layer support.
> > > > >
> > > > > Reporting the tuple size is a good idea.  But is that enough for
> > > > > the existing nvme-cli use case?
>
> 'nvme list' is just listening the block size and the meta size in the
> 'Format' field. So nothing really crazy going on:
>
>    Usage                      Format
>    -------------------------- ----------------
>    343.33  GB / 512.11  GB    512   B +  0 B
>
> nvme-cli commands like 'nmve ns-id' etc will always issue a command so
> that is not a concern. It's just the libnvme nvme_scan_topology() call
> which should stop issuing any commands.
>
> I'll add the missing tuple_size to the integrity sysfs dir in this case.
>
> > > > nvme-cli currently queries with admin passthrough identify command, so
> > > > adding a new attribute won't break that. I assume Daniel would have it
> > > > fallback to that same command for backward compatibilty if a desired
> > > > sysfs attribute doesn't exist.
>
> Yes, a fallback will exist. There is no need to break existing users.
>
> In summary, the only missing entries are
>
>   - csi
>   - tuple_size
>   - nuse

I agree with the comments made, especially the one made by Christoph
that these values should be added to the nshead.