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From:   Olga Kornievskaia <olga.kornievskaia@gmail.com>
Date:   Wed, 8 Jul 2020 17:04:36 -0400
Message-ID: <CAN-5tyGLQbzWEHBsmRuZ0LAWHNBobQ50cEOMp_REvWpa6SOjbw@mail.gmail.com>
Subject: Re: [PATCH 1/1] SUNRPC dont update timeout value on connection reset
To:     Trond Myklebust <trondmy@hammerspace.com>
Cc:     "anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
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On Sun, Jun 28, 2020 at 5:16 PM Trond Myklebust <trondmy@hammerspace.com> wrote:
>
> On Sun, 2020-06-28 at 14:03 -0400, Olga Kornievskaia wrote:
> > Trond/Anna,
> >
> > Any comments on this patch?
> >
> > On Tue, Jun 23, 2020 at 11:22 AM Olga Kornievskaia
> > <olga.kornievskaia@gmail.com> wrote:
> > > Current behaviour: every time a v3 operation is re-sent to the
> > > server
> > > we update (double) the timeout. There is no distinction between
> > > whether
> > > or not the previous timer had expired before the re-sent happened.
> > >
> > > Here's the scenario:
> > > 1. Client sends a v3 operation
> > > 2. Server RST-s the connection (prior to the timeout) (eg.,
> > > connection
> > > is immediately reset)
> > > 3. Client re-sends a v3 operation but the timeout is now 120sec.
>
> Ah... The problem here is clearly '3.' incrementing the timeout value
> before we've actually hit a minor or major timeout...
>
> So I think we want to look carefully at xprt_adjust_timeout(). The
> first rule there should be that if we're below the threshold for a
> minor timeout, we just want to exit without changing anything.
>
> The second rule is then that if we're below the threshold for a major
> timeout, then we adjust the timeout value by doubling it (if to-
> >to_exponential) or adding the value to->to_increment (if !to-
> >to_exponential) and then exit.
>
> Finally, if this is a major timeout, we reset req->rq_timeout to to-
> >to_initval, reset req->rq_retries, call xprt_reset_majortimeo(), reset
> the RTT counters and return ETIMEDOUT.
>
> None of this should be specific to your connection reset case. This is
> how we want timeouts to work in the generic case, so we need to fix
> that.
>

Ok thanks for comments. I don't know if I got it right but I submitted
a new version.

> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
>
>