From: "J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: flock LOCK_EX hangs
Date: Wed, 16 May 2007 13:30:08 -0400
Message-ID: <20070516173008.GD9895@fieldses.org>
References: <20070516131253.GC19167@radix50.net>
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Cc: nfs@lists.sourceforge.net
To: Baurzhan Ismagulov <ibr@radix50.net>
In-Reply-To: <20070516131253.GC19167@radix50.net>
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On Wed, May 16, 2007 at 03:12:53PM +0200, Baurzhan Ismagulov wrote:
> I'm experiencing problems with the kernel NFS server. The client hangs
> on the flock call. This is Debian etch, Linux 2.6.16-1-686-smp, the
> server and the client is the same machine. The directory is exported
> with rw, no mount options. The lockd kernel thread is present, rpcinfo
> -p reports nlockmgr registered, the firewall passes all the traffic
> through.
> 
> I've googled and searched the list archive, the postings are usually
> quite old (only two were from 2006 and referred to Linux 2.6), and I
> couldn't see how I could further analyze the problem. I've also tried
> mounting with nolock, but this apparently makes flock / fcntl to fail,
> since the tools I use (automake and debootstrap, although I checked this
> only with the latter) exited with an error code, and I rely upon it.

Might be fun to watch the network traffic as this is happening.  I'd
probably do something like

	wireshark -Slk -ilo

then try to get a lock, and try to understand what's happening on the
"network": is the client sending requests that the server doesn't
answer?  Or are there errors coming back?  Etc.

Or you could run

	tcpdump -s0 -ilo -wtmp.pcap

and mail a copy of tmp.pcap and somebody could take a look.

There's also been a lot fixed since 2.6.16, so it might be worth trying
something newer.

--b.

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