linux-ext4 - Re: [PATCH] [RFC] remove ext3 inode from orphan list when link and unlink race

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Date:	Sun, 14 Jan 2007 09:42:05 -0600
From:	Eric Sandeen <sandeen@...hat.com>
To:	Dmitriy Monakhov <dmonakhov@...ru>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] [RFC] remove ext3 inode from orphan list when link and
 unlink race

Dmitriy Monakhov wrote:
> Eric Sandeen <sandeen@...hat.com> writes:
> 
>> I've been looking at a case where many threads are opening, unlinking, and
>> hardlinking files on ext3 .
> How many concurent threads do you use and how long does it takes to trigger 
> this race? I've tried to reproduce this with two threads, but not succeed.
> <thread 1>  
>         fd = create("src")
>         close(fd)
>         unlink("src")
> <thread 2>
>         link("src", "dst")
>         unlink("dst")
> 
> Original testcase will be the best answer :).

Sure :)  Though I didn't write it... see this collection of bash scripts:

http://people.redhat.com/esandeen/testcases/orphan-repro.tar.bz2

I didn't write it, but it exposed the bug for me.  The VAR file contains 
variables to specify mountpoint and a device, which the script starts by 
mkfs'ing, so be warned.

It spawns -many- threads, and on my 4 CPU opteron I can hit it in a 
reasonable amount of time.  It would probably be nice to have a more 
targeted testcase but it did the trick for me.

Thanks,
-Eric

> Thanks.

-
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