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Date:   Thu, 17 Feb 2022 21:15:38 +0100 (CET)
From:   Richard Weinberger <richard@nod.at>
To:     bfields <bfields@fieldses.org>
Cc:     linux-nfs <linux-nfs@vger.kernel.org>, david <david@sigma-star.at>,
        luis turcitu <luis.turcitu@appsbroker.com>,
        david young <david.young@appsbroker.com>,
        david oberhollenzer <david.oberhollenzer@sigma-star.at>,
        trond myklebust <trond.myklebust@hammerspace.com>,
        anna schumaker <anna.schumaker@netapp.com>,
        chris chilvers <chris.chilvers@appsbroker.com>
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In-Reply-To: <20220217192726.GB16497@fieldses.org>
References: <20220217131531.2890-1-richard@nod.at> <20220217163332.GA16497@fieldses.org> <1525788049.60261.1645118835162.JavaMail.zimbra@nod.at> <20220217192726.GB16497@fieldses.org>
Subject: Re: [RFC PATCH 0/6] nfs-utils: Improving NFS re-exports
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----- Ursprüngliche Mail -----
> Von: "bfields" <bfields@fieldses.org>
>> Which one do you prefer?
>> "predefined-fsidnum" should be the safest one to start.
> 
> I don't know!  I'll have to do some more reading and think about it.

No need to worry, take your time.
 
>> > Setting the timeout to 0 doesn't help with re-export server reboots.
>> > After a reboot is another case where we could end up in a situation
>> > where a client hands us a filehandle for a filesystem that isn't mounted
>> > yet.
>> > 
>> > I think you want to keep a path with each entry in the database.  When
>> > mountd gets a request for a filesystem it hasn't seen before, it stats
>> > that path, which should trigger the automounts.
>> 
>> I have implemented that already. This feature is part of this series. :-)
> 
> Oh, good, got it.  It'll take me some time to catch up.

The reason why setting the timeout to 0 is still needed is because
when mountd uncovers a subvolume but no client uses it a filehandle,
it is not locked and can be unmounted later.
Only when nfsd sees a matching filehandle the reference counter will
be increased and umounting is no longer possible.

Thanks,
//richard