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Message-ID: <85b02061798a1b750a87b0302681b86651d0c7a3.camel@kernel.org>
Subject: Re: [PATCH v6 3/3] NFSD: add write_ports to netlink command
From: Jeff Layton <jlayton@kernel.org>
To: Lorenzo Bianconi <lorenzo@kernel.org>, Chuck Lever
 <chuck.lever@oracle.com>
Cc: NeilBrown <neilb@suse.de>, linux-nfs@vger.kernel.org, 
	lorenzo.bianconi@redhat.com, kuba@kernel.org, horms@kernel.org, 
	netdev@vger.kernel.org
Date: Tue, 23 Jan 2024 06:17:15 -0500
In-Reply-To: <Za-N6BxOMXTGyxmW@lore-desk>
References: <cover.1705771400.git.lorenzo@kernel.org>
	 <f7c42dae2b232b3b06e54ceb3f00725893973e02.1705771400.git.lorenzo@kernel.org>
	 <9e3ae337dcf168c60c4cfd51aa0b2fc7b24bcbfb.camel@kernel.org>
	 <170595930799.23031.17998490973211605470@noble.neil.brown.name>
	 <Za7zHvPJdei/vWm4@tissot.1015granger.net> <Za-N6BxOMXTGyxmW@lore-desk>
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On Tue, 2024-01-23 at 10:59 +0100, Lorenzo Bianconi wrote:
> > On Tue, Jan 23, 2024 at 08:35:07AM +1100, NeilBrown wrote:
> > > On Tue, 23 Jan 2024, Jeff Layton wrote:
> > > > On Sat, 2024-01-20 at 18:33 +0100, Lorenzo Bianconi wrote:
> > > > > Introduce write_ports netlink command. For listener-set, userspac=
e is
> > > > > expected to provide a NFS listeners list it wants to enable (all =
the
> > > > > other ports will be closed).
> > > > >=20
> > > >=20
> > > > Ditto here. This is a change to a declarative interface, which I th=
ink
> > > > is a better way to handle this, but we should be aware of the chang=
e.
> > >=20
> > > I agree it is better, and thanks for highlighting the change.
> > >=20
> > > > > +	/* 2- remove stale listeners */
> > > >=20
> > > >=20
> > > > The old portlist interface was weird, in that it was only additive.=
 You
> > > > couldn't use it to close a listening socket (AFAICT). We may be abl=
e to
> > > > support that now with this interface, but we'll need to test that c=
ase
> > > > carefully.
> > >=20
> > > Do we ever want/need to remove listening sockets?
> >=20
> > I think that might be an interesting use case. Disabling RDMA, for
> > example, should kill the RDMA listening endpoints but leave
> > listening sockets in place.
> >=20
> > But for now, our socket listeners are "any". Wondering how net
> > namespaces play into this.
> >=20
> >=20
> > > Normal practice when making any changes is to stop and restart where
> > > "stop" removes all sockets, unexports all filesystems, disables all
> > > versions.
> > > I don't exactly object to supporting fine-grained changes, but I susp=
ect
> > > anything that is not used by normal service start will hardly ever be
> > > used in practice, so will not be tested.
> >=20
> > Well, there is that. I guess until we have test coverage for NFSD
> > administrative interfaces, we should leave well enough alone.
>=20
> So to summarize it:
> - we will allow to remove enabled versions (as it is in patch v6 2/3)
> - we will allow to add new listening sockets but we will not allow to rem=
ove
> =A0=A0them (the user/admin will need to stop/start the server).
>=20
> Agree? If so I will work on it and post v7.
>=20
>=20

That sounds about right to me. We could eventually relax the restriction
about removing sockets later, but for now it's probably best to prohibit
it (like Neil suggests).


>=20
> >=20
> >=20
> > > So if it is easiest to support reverting previous configuration (as i=
t
> > > probably is for version setting), then do so.  But if there is any
> > > complexity (as maybe there is with listening sockets), then don't
> > > add complexity that won't be used.
> > >=20
> > > Thanks,
> > > NeilBrown
> >=20
> > --=20
> > Chuck Lever

--=20
Jeff Layton <jlayton@kernel.org>