linux-kernel - Re: regression, bisected: getcwd() ENOENT on NFS4...

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Message-ID: <6278d2220911010447v5889b9bbt33f685ef7669cc45@mail.gmail.com>
Date:	Sun, 1 Nov 2009 12:47:26 +0000
From:	Daniel J Blueman <daniel.blueman@...il.com>
To:	Trond Myklebust <Trond.Myklebust@...app.com>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-nfs@...r.kernel.org
Subject: Re: regression, bisected: getcwd() ENOENT on NFS4...

Hi Trond,

On Mon, Oct 26, 2009 at 1:19 PM, Trond Myklebust
<Trond.Myklebust@...app.com> wrote:
> On Sun, 2009-10-25 at 23:31 +0000, Daniel J Blueman wrote:
>> Since 2.6.30-rc, I've been experiencing various issues relating to
>> getcwd() returning ENOENT on NFS4 clients. I used an over-complicated
>> but reliable reproducer [1] (on Karmic RC against a 2.6.32-rc5 NFS4
>> server) to bisect [2].
>>
>> The impact of this regression is moderate (side-effects range from
>> benign to failure), so we should get a fix into 2.6.32 if at all
>> possible and strongly consider a 2.6.31 stable update.
>>
>> Thanks,
>>   Daniel
>>
>> --- [1]
>>
>> $ apt-get source apt
>> $ cd apt-*
>> $ ./configure && make
>> [snip]
>> sh: getcwd() failed: No such file or directory
>>
>> --- [2]
>>
>> a65318bf3afc93ce49227e849d213799b072c5fd is first bad commit
>> commit a65318bf3afc93ce49227e849d213799b072c5fd
>> Author: Trond Myklebust <Trond.Myklebust@...app.com>
>> Date:   Wed Mar 11 14:10:28 2009 -0400
>>
>>     NFSv4: Simplify some cache consistency post-op GETATTRs
>
> I'm having a lot of trouble seeing how this patch could result in
> ENOENT. All it should be doing is reducing the frequency with which we
> update some of the inode metadata.
>
> Have you ever been able to capture one of these errors using strace?

Backing this patch out by hand against stock 2.6.32-rc5 (w/ 2.6.32-rc5
on server) corrects the behaviour. It's readily reproducible [1];
using 2.6.30, the issue is not seen, thus is a regression.

To observe the change to user-level behaviour (after the reproducer commands):
# make clean
# strace -ffe getcwd make -n >list
[pid  3829] getcwd(0x7fffa269a380, 4096) = -1 ENOENT (No such file or directory)
make: getcwd: No such file or directory

Would this help for me to log this via a bugzilla.kernel.org ticket?

Thanks,
  Daniel

--- [1]

booting eg:
http://mira.sunsite.utk.edu/ubuntu-releases/karmic/ubuntu-9.10-desktop-amd64.iso

$ sudo bash
# apt-get install build-essential
# apt-get build-dep apt
# mount server:/ /mnt -tnfs4 && cd /mnt
# apt-get source apt
# cd apt-0.7.23.1ubuntu2
# ./configure && make
 -> "getcwd: No such file or directory" messages observed with cited
patch and not without
-- 
Daniel J Blueman
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