linux-kernel - Re: [PATCH v2] Fix AFFS race condition.

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Date:	Mon, 14 May 2012 12:54:30 +0200
From:	Vladimir 'φ-coder/phcoder' Serbinenko 
	<phcoder@...il.com>
To:	Marco Stornelli <marco.stornelli@...il.com>
CC:	Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
	Josef Bacik <josef@...hat.com>
Subject: Re: [PATCH v2] Fix AFFS race condition.

On 14.05.2012 12:40, Marco Stornelli wrote:

> 2012/5/14 Jan Kara <jack@...e.cz>:
>> On Sun 13-05-12 15:44:33, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
>>> AFFS code preallocates several blocks as an optimisation. Unfortunately
>>> it's not protected by lock so the same blocks may end up allocated twice.
>>> Here is a fix.
>>>
>>> Signed-off-by: Vladimir Serbinenko <phcoder@...il.com>
>>  The patch looks good to me now. Thanks! You can add:
>> Reviewed-by: Jan Kara <jack@...e.cz>
>>
>>  Al, will you merge this patch through your tree? AFFS does not seem to
>> have a maintainer so you are a default fallback...
>>
>>                                                                Honza
>>
> 
> I don't know the AFFS code, so only a question. Instead to use a spin
> lock, I think we can use a simple mutex. Or is the spin lock
> mandatory?

My first version used mutex. But then Jan suggested that since the
critical section is very short and doesn't contain any instructions
which might sleep, it's better for performance to use a spin lock.

-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko


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