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Message-ID: <e85381f3d7575d8784f54c5a3abdb60be190c4af.camel@kernel.org>
Subject: Re: [PATCH v5 3/3] NFSD: convert write_ports to netlink command
From: Jeff Layton <jlayton@kernel.org>
To: Lorenzo Bianconi <lorenzo@kernel.org>, Chuck Lever
 <chuck.lever@oracle.com>
Cc: linux-nfs@vger.kernel.org, lorenzo.bianconi@redhat.com, neilb@suse.de, 
	netdev@vger.kernel.org, kuba@kernel.org
Date: Thu, 30 Nov 2023 11:55:29 -0500
In-Reply-To: <c87becd9af15ad9447030c17dee9c481a8d25442.camel@kernel.org>
References: <cover.1701277475.git.lorenzo@kernel.org>
	 <67251eabfbbccb806991e6437ebcf1cf00166017.1701277475.git.lorenzo@kernel.org>
	 <7b21c962c2a6c552c9807d6f382e1097da4ba748.camel@kernel.org>
	 <ZWhcc8384pf11sAu@lore-desk>
	 <c87becd9af15ad9447030c17dee9c481a8d25442.camel@kernel.org>
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On Thu, 2023-11-30 at 11:22 -0500, Jeff Layton wrote:
> On Thu, 2023-11-30 at 10:57 +0100, Lorenzo Bianconi wrote:
> > > >=20
> > > > +/* =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D NFSD_CMD_LISTENER_ST=
ART =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D */
> > > > +/* NFSD_CMD_LISTENER_START - do */
> > > > +struct nfsd_listener_start_req {
> > > > +	struct {
> > > > +		__u32 transport_name_len;
> > > > +		__u32 port:1;
> > > > +	} _present;
> > > > +
> > > > +	char *transport_name;
> > > > +	__u32 port;
> > > > +};
> > >=20
> > > How do you deconfigure a listener with this interface? i.e. suppose I
> > > want to stop nfsd from listening on a particular port? I think this t=
oo
> > > is a place where a declarative interface would be better:
> >=20
> > Is it possible with current APIs? as for 2/3 so far I have just added n=
etlink
> > counter for current implementation but I am fine to change the logic he=
re to
> > better APIs.
> >=20
> > >=20
>=20
> No, I don't think you can do this with the current API at all. I
> consider it a major deficiency. I don't think we want to repeat that
> mistake in the new interface.
>=20
> > > Have userland send down a list of the ports that we should currently =
be
> > > listening on, and let the kernel do the work to match the request. Ag=
ain
> > > too, an empty list could mean "close everything".
> > >=20
> > >=20
>=20

Another thought: should this interface also report and allow you to
specify the address to listen on?

When the write_ports interface was first created, it lacked a field for
the address to listen on.=A0Later we added a way to just hand off a socket
to the kernel to pass that info.

I think it's possible today to send down a socket that only listens on a
particular address, and you have no real way to tell that with the
current "ports" file.

Should we instead plumb a complete struct sockaddr_storage (or some
other suitable address structure) into this interface?
--=20
Jeff Layton <jlayton@kernel.org>