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Date:   Mon, 27 Nov 2023 17:33:33 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Keith Busch <kbusch@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>, Daniel Wagner <dwagner@suse.de>,
        linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        Sagi Grimberg <sagi@grimberg.me>,
        Hannes Reinecke <hare@suse.de>
Subject: Re: [RFC v1] nvme: add cse, ds, ms, nsze and nuse to sysfs
Message-ID: <20231127163333.GA2273@lst.de>
References: <20231127103208.25748-1-dwagner@suse.de> <20231127141857.GA25833@lst.de> <ZWS5dM5FzTMr5ftO@kbusch-mbp.dhcp.thefacebook.com> <20231127155649.GA1403@lst.de> <ZWTEFvYbI1bFTXyZ@kbusch-mbp.dhcp.thefacebook.com>
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On Mon, Nov 27, 2023 at 09:30:14AM -0700, Keith Busch wrote:
> > > 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-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.  But does it care about the tuple size, or the actual size of the
metadata field even if is bigger than the PI tuple?