From: Neil Brown <neilb@suse.de>
Subject: Re: Regression: NFS locking hangs when statd not running.
Date: Tue, 24 Oct 2006 12:17:02 +1000
Message-ID: <17725.30622.629579.910456@cse.unsw.edu.au>
References: <17720.41873.549441.330938@cse.unsw.edu.au>
	<20061020124119.GE27351@suse.de>
	<17725.26376.280902.571606@cse.unsw.edu.au>
	<1161654839.6487.20.camel@lade.trondhjem.org>
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Cc: Olaf Kirch <okir@suse.de>, Takashi Iwai <tiwai@suse.de>,
	Chuck Lever <chuck.lever@oracle.com>, nfs@lists.sourceforge.net
To: Trond Myklebust <trond.myklebust@fys.uio.no>
In-Reply-To: message from Trond Myklebust on Monday October 23
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On Monday October 23, trond.myklebust@fys.uio.no wrote:
> On Tue, 2006-10-24 at 11:06 +1000, Neil Brown wrote:
> > Due to the state-management nature of lockd requests, I think they
> > need to be hard,nointr always (as they currently are) otherwise the
> > client and server can get out-of-sync causing serious confusion.
> 
> Not really. As long as the interrupted lock request is followed by an
> UNLOCK request, you should be safe.

Yes, I guess so.  Do we do that?  Send an UNLOCK if a LOCK fails
mysteriously?

> 
> 
> > When talking to statd or local portmap we really want to abort if
> > statd says 'no', or if we get ECONREFUSED from portmap, and probably
> > even if we get ECONREFUSED from statd.... though I'm not 100% certain
> > about the last.
> > But if statd is slow, we still want to retry.
> 
> No. We should back off and retry. If the user wants to be able to lock,
> then the kernel shouldn't be overriding that choice. Only if the user
> specifies "nolock" should we fall back to local locking.

Certainly we should only fall back to lock locking if 'nolock' was
given.  But in what circumstances can we return -ENOLOCK?
I'm suggesting that if statd isn't running, then the best thing is to
return -ENOLOCK quickly.  Currently we block uninterruptible for 30
seconds (on a tcp mount).  For every lock request.

NeilBrown

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