linux-kernel - Re: [regression] nfs4: 30 second delay during umount of remote fs on system shutdown

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Date:	Thu, 28 Feb 2008 20:55:16 -0800
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Frans Pop <elendil@...net.nl>
Cc:	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [regression] nfs4: 30 second delay during umount of remote fs
	on system shutdown


On Fri, 2008-02-29 at 02:03 +0100, Frans Pop wrote:
> On Thursday 28 February 2008, Trond Myklebust wrote:
> > On Thu, 2008-02-28 at 18:29 +0100, Frans Pop wrote:
> > > I have verified that portmap is also not running during S31umountnfs.sh
> > > with 2.6.24, so apparently there has been a change in the kernel that
> > > has made umount look for portmap and cause the 30 second delay if it is
> > > not running.
> >
> > You are probably seeing the effect of lockd going down: it always
> > attempts to unregister from the portmapper (and no, this is _not_ new
> > behaviour).
> 
> It is _very much_ new behavior because as soon as I boot (and shut down) 
> with a 2.6.24 kernel the problem completely disappears. Userland is *100% 
> identical* between my tests.

The "new behaviour" is that we fixed a bug whereby the lockd code was
failing to flush signals before attempting the rpc unregister. The sad
fact is that userland appears to have been 100% broken for some time.
The difference is that it was able to get away with it earlier...

> > If debian is killing the portmapper while lockd is still up, then that
> > is a definite debian bug...
> 
> I have no idea about that. AFAICT lockd is not even running (at least, 
> there's no process named lockd, even when the system is running normally.
> Isn't lockd an nfs3 thing? I'm using nfs4 here.

NFSv4 has a delegation recall server to kill. Same difference...

Trond

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