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Date:      Tue, 4 Jun 2019 00:30:13 +0000
From:      Rick Macklem <rmacklem@uoguelph.ca>
To:        Alan Somers <asomers@freebsd.org>
Cc:        Peter Eriksson <pen@lysator.liu.se>, "freebsd-fs@freebsd.org" <freebsd-fs@FreeBSD.org>
Subject:   Re: RFC: should an incremental reload of exports for mountd be optional?
Message-ID:  <YQXPR01MB3128E549A195DF4B8DAD191BDD150@YQXPR01MB3128.CANPRD01.PROD.OUTLOOK.COM>
In-Reply-To: <CAOtMX2i23Gup6EZvVB9rL9HcCRarMroD=-O6W_OfDV_0Uz5n_Q@mail.gmail.com>
References:  <QB1PR01MB2643E5186098E2AF14934866DD190@QB1PR01MB2643.CANPRD01.PROD.OUTLOOK.COM> <D685FA4E-0F35-44F8-B341-CF59122E10B9@lysator.liu.se> <CAOtMX2hs-aQgEZaCQjNdMHuL8qxJTqnnvNQ%2BysRcpFFTEtDb1A@mail.gmail.com> <YQXPR01MB31289FF0AC8633D372C814A2DD140@YQXPR01MB3128.CANPRD01.PROD.OUTLOOK.COM>, <CAOtMX2i23Gup6EZvVB9rL9HcCRarMroD=-O6W_OfDV_0Uz5n_Q@mail.gmail.com>

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Alan Somers wrote:
>Will a restart of the daemon cause clients to get HUPped if they try
>to access an exported filesystem while mountd is restarting?
>-Alan
I'm not sure what you mean by HUPped, but during a restart of mountd, extan=
t
mounts should continue to work.

What will fail during the mountd restart is new NFSv3 mount attempts, becau=
se
they won't be able to talk to mountd via the Mount protocol. Usually the
failure will be rpcbind not having MOUNTPROG registered.
Then a retry of the mount (which will happen after something like 30sec if =
you
don't <ctrl>C the mount command) will succeed, assuming mountd has restarte=
d.
Unmounts will complain the MOUNTPROG wasn't registered, but the umount
will work anyhow.

Then "showmount", which is never guaranteed to return correct info, will re=
port it
as still mounted. Since "showmount" never knows about NFSv4 mounts and just
returns its guess at what is mounted, I don't find it useful anyhow.

 NFSv4 mounts should continue to work when mountd isn't running, since they=
 don't use the Mount protocol. And, since they don't use the Mount protocol=
, "showmount"
never knows about them.

So, I restart can cause some disruption, but they are mostly just delays wh=
en doing
new NFSv3 mounts on the server.

rick

On Mon, Jun 3, 2019 at 5:13 PM Rick Macklem <rmacklem@uoguelph.ca> wrote:
>
> Thanks everyone for your comments. I just committed the patch with
> the incremental reload of exports always enabled.
> If people run into problems, I can add some "backdoor" way to disable
> it, as suggested by asomers@.
>
> A restart of the daemon will always do a full reload to work around any
> reload failures.
>
> rick
>
[stuff snipped]=



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