linux-ext4 - Re: double free of blocks occurred during online defrag

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Message-ID: <49AB993B.8050705@sx.jp.nec.com>
Date:	Mon, 02 Mar 2009 17:30:51 +0900
From:	Kazuya Mio <k-mio@...jp.nec.com>
To:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
CC:	linux-ext4@...r.kernel.org
Subject: Re: double free of blocks occurred during online defrag

Hi Aneesh,

Thanks for your reply.

Aneesh Kumar K.V wrote:
> We dropped the patch because I found that the double free in my case was
> not exactly due the explanation given in the patch above.
> 
> I asked to drop the patch in
> 
> http://article.gmane.org/gmane.comp.file-systems.ext4/10199
> 
> I also found that the patch is not completely correct. The meta-data
> blocks which are added to the free_list are not allocated from any
> prealloc space.
> 
> So what you are seeing may be a different problem which the patch is
> hiding from happening.  I guess you will have to look more closely at why the
> double-free is happening in your case.
> 
> -aneesh
> 

I thought that the problem would be solved if we check whether on-disk and buddy
bitmap is different or not when inode prealloc space is released.
However, my understanding was incorrect.
I will continue examining this problem.

Best regards,
Kazuya Mio
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