linux-kernel - Re: 3.1rc7+ FSX failure over NFS

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Message-ID: <1317324133.8708.43.camel@lade.trondhjem.org>
Date:	Thu, 29 Sep 2011 15:22:13 -0400
From:	Trond Myklebust <Trond.Myklebust@...app.com>
To:	Dave Jones <davej@...hat.com>
Cc:	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: 3.1rc7+ FSX failure over NFS

On Thu, 2011-09-29 at 15:05 -0400, Dave Jones wrote: 
> On Thu, Sep 29, 2011 at 02:59:32PM -0400, Trond Myklebust wrote:
>  
>  > 1) What filesystem are you using on the server, and does that filesystem
>  > support high resolution timestamps?
> 
> ext3

Hmm... Is the problem also reproducible with ext4 or xfs?

ext3 has the issue that mtime/ctime timestamps are only accurate to
within 1 second, and so the client often has trouble figuring out which
returned attribute values reflect the most recent state on the server
when several RPC calls have been transmitted in parallel. 

> > 2) Does the file length on the server match the reported erroneous file
>  > length on the client?
> 
> No. Server side is 213853 bytes (0x3435d)

Ouch. That would seem to indicate that something is happening after the
truncate(). I would have expected the server to show 0x3210a...

> > 3) Do the mtime and ctime on the erroneous file match on the client and
>  > server?
>  
> both show..
> Modify: 2011-09-29 13:50:00.000000000 -0400

OK. This result looks consistent with the hypothesis put forward under
question (1) above. However your reply to (2) does not. Let me
investigate and see if I can reproduce it...

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@...app.com
www.netapp.com

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