Re: [PATCH 4/4] systemd: Apply all sysctl settings through udev rule when NFS-related modules are loaded

From: Michael Prokop <mika@debian.org>
To: Salvatore Bonaccorso <carnil@debian.org>
Cc: NeilBrown <neilb@suse.de>, Steve Dickson <steved@redhat.com>,
	linux-nfs@vger.kernel.org,
	Andras Korn <korn-debbugs@elan.rulez.org>,
	Marco d'Itri <md@linux.it>
Subject: Re: [PATCH 4/4] systemd: Apply all sysctl settings through udev rule when NFS-related modules are loaded
Date: Fri, 25 Nov 2022 17:27:57 +0100	[thread overview]
Message-ID: <2022-11-25T17-23-34@devnull.michael-prokop.at> (raw)
In-Reply-To: <Y4DrlX+oZyjYtrS8@eldamar.lan>

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Hi!

* Salvatore Bonaccorso [Fri Nov 25, 2022 at 05:21:41PM +0100]:
> On Fri, Nov 25, 2022 at 02:29:35PM +0100, Michael Prokop wrote:
> > * Salvatore Bonaccorso [Fri Nov 25, 2022 at 02:07:25PM +0100]:

> > > --- /dev/null
> > > +++ b/systemd/60-nfs.rules
> > > @@ -0,0 +1,21 @@
> > > +# Ensure all NFS systctl settings get applied when modules load
> > > +
> > > +# sunrpc module supports "sunrpc.*" sysctls
> > > +ACTION=="add", SUBSYSTEM=="module", KERNEL=="sunrpc", \
> > > +  RUN+="/sbin/sysctl -q --pattern ^sunrpc --system"
> > [...]
> > 
> > Thanks for taking care of this problem, Salvatore!
> 
> Thanks to you for prodding about it, hope to bring the issue bit
> forward with the series proposal.

ACK, thanks, I highly appreciate your efforts!

> > AFAICT even latest busybox's sysctl does not support the `--pattern`
> > option yet:
> > 
> > | sysctl: unrecognized option '--pattern'
> > | BusyBox v1.35.0 (Debian 1:1.35.0-4) multi-call binary.
> > | [....]
> > 
> > So any initramfs that uses busybox and its sysctl (like in Debian)
> > and trying to apply above udev rules might fail?
> 
> But would this actually be a problem for us here? There is no hook
> script which would copy the 60-nfs.rules (not relevant in initrd) to
> the initrd. The rule only would apply on module load outside the
> initrd.

Indeed, I also think that as long as this udev rule doesn't end up
in the initrd there shouldn't be any problem with it.

> There is only a subset of rules which would be copied into initrd,
> like the ones in hook/udev. But 60-nfs.rules would be specific to
> nfs-utils, which does not provide a initramfs-tools hook to include
> the rules into initrd.

Good point, thanks for checking and clarifying.

> Now the question you raise, is, do they need to be handled actually
> already as well in initrd? You are correct, when handled through the
> previous mechanism with modrobe.d configuration, 50-nfs.conf was added
> to initramfs:
> 
> usr/lib/modprobe.d/50-nfs.conf 
> 
> (and causing the issues seen).
> 
> Please correct me if I missed something from the picture.

No, I think you're right and AFAICS we shouldn't see the issues we
originally noticed any longer. Thanks! :)

regards
-mika-

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