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Date:   Wed, 9 Aug 2023 08:53:39 -0400
From:   Chuck Lever <chuck.lever@oracle.com>
To:     Lorenzo Bianconi <lorenzo@kernel.org>
Cc:     Jeff Layton <jlayton@kernel.org>, NeilBrown <neilb@suse.de>,
        linux-nfs@vger.kernel.org, lorenzo.bianconi@redhat.com
Subject: Re: [PATCH] NFSD: add version field to nfsd_rpc_status_show handler
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On Wed, Aug 09, 2023 at 09:49:55AM +0200, Lorenzo Bianconi wrote:
> > Lorenzo, I'll drop the v5 of this series from nfsd-next. When you're
> > ready, please send another version with the discussed changes
> > squashed in.
> 
> ack, fine to me. Just a couple of questions:
> - do we want to expose the output in yaml or is it enough to fix the NFSv4 COMPOUND
>   parsing using ":" as sub-delimiter (and add a placeholder for non NFSv4 COMPOUND)?
>   The yaml approach downside is we will need to add some specific code since afaik
>   there isn't any yaml code we can rely on in the kernel, right?

Would you mind spinning a series with the simple delimiter changes
and the other things we've discussed so far? It seems we have some
items that still need sorting before tackling netlink v. sysfs.


> - what about netlink? I would say we can have both of them (cat + netlink) so
>   the user does not need to have a specific userspace tool to decode the info.

The trend in network subsystems is to use netlink and a purpose-
built tool, no "cat" support. The trouble with "cat" is we can't
seem to decide on where to put the output file.

Also, I notice that rq_flags appears for each in-flight request in
raw hexadecimal form. That's not especially user-friendly and cries
out for a tool to interpret the bits in that field. (Actually IIRC
there is now a tool that can take a yaml-defined netlink protocol
and perform each of the protocol's operations and spit out the
raw results).

I'm wondering if having support for "cat" is really just an old
habit we need to discard.


Re: netlink... folks should keep in mind that the output would not
be yaml. netlink uses yaml to define the netlink protocol, which is
quite like SunRPC. This still meets our extensibility requirements,
IMO.

Creating a netlink protocol would provide a vehicle for exporting
other information. Once there is an NFSD-specific netlink protocol,
it's straightforward to define an additional netlink procedure for
any of the information that are now available in /proc/fs/nfsd/
files.


> I will work on v6 as soon as we have agreed on the points above.

Thanks, I appreciate it!


-- 
Chuck Lever