From:   NeilBrown <neilb@suse.com>
To:     "J. Bruce Fields" <bfields@fieldses.org>
Date:   Tue, 26 Mar 2019 10:00:54 +1100
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH] sunrpc/cache: handle missing listeners better.
In-Reply-To: <20190325222108.GB22644@fieldses.org>
References: <87pnqj64br.fsf@notabene.neil.brown.name> <20190322165338.GB7692@fieldses.org> <87bm225ymv.fsf@notabene.neil.brown.name> <20190325222108.GB22644@fieldses.org>
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On Mon, Mar 25 2019, J. Bruce Fields wrote:

> On Sat, Mar 23, 2019 at 09:32:08AM +1100, NeilBrown wrote:
>> On Fri, Mar 22 2019, J. Bruce Fields wrote:
>> > I've gotten complaints about the same thing and said "well, in
>> > retrospect we shouldn't have designed the interface this way, but we
>> > did, so just stop opening those files".
>>=20
>> As the fool who actually "designed" this,
>
> Pretty sure I was there too and had my chance to object.  In any case,
> hope you didn't take that as a personal complaint about your work, it
> (along with lots of maintenance since then) is much appreciated.

Not at all, I was just feeling in a self-deprecatory mood.

>
>> I can say with some confidence that the intention was always the
>> requests would block for at most 30 seconds.
> ...
>> > One advantage of waiting for mountd to come back is that you could
>> > upgrade mountd in place.  That shouldn't take 30 seconds, though.  And=
 I
>> > haven't heard of anyone actually doing that.
>>=20
>> Surely upgrading of mountd in-place happens whenever you install a new
>> version.
>
> I didn't think distros restarted mountd on upgrade, but I haven't
> actually checked that.  I agree that it's something we should allow,
> anyway.

I just had a look at the openSUSE nfs-kernel-server package.  It
declares

  %service_add_post nfs-mountd.service nfs-server.service

where %service_add_post is an rpm macro which does various things that I
struggle to understand, but it does reference a setting in
/etc/sysconfig/services, which contains

#
# Do you want to disable the automatic restart of services when
# a new version gets installed?
#
DISABLE_RESTART_ON_UPDATE=3D"no"

So I'm going to guess that openSUSE does restart mountd on upgrade.

>
>> > It's too bad that not opening auth.unix.gid is the only way for mountd
>> > to communicate that gids shouldn't be mapped.
>>=20
>> I have a general preference for reusing existing functionality rather
>> than creating new special-purpose functionality.  I think this has
>> served me well more often than not.  Maybe this is one case of "not".
>>=20
>> If you want to restart mountd without --managed-gids (where previously
>> it had that option), there is a chance that you will hit this problem.
>> That is a case where the answer "just stop opening those files" doesn't
>> really apply.
>
> Yeah.  OK, applying.
>
> (But I'm traveling and may not get this tested and pushed out till next
> week.)

No rush.  Safe travels.

Thanks,
NeilBrown


>
> --b.

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