linux-ext4 - Re: [PATCH V3] fix bb_prealloc_list corruption due to wrong group locking

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Message-ID: <49C11E85.3040300@redhat.com>
Date:	Wed, 18 Mar 2009 11:17:09 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Frank Mayhar <fmayhar@...gle.com>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH V3] fix bb_prealloc_list corruption due to wrong group
 locking

Frank Mayhar wrote:
> On Mon, 2009-03-16 at 10:53 -0700, Frank Mayhar wrote: 
>> On Mon, 2009-03-16 at 12:48 -0500, Eric Sandeen wrote:
>>> Hi Frank - I don't *think* so just because deleted items are poisoned
>>> and I would expect that we'd trip over a bad pointer in the corrupted
>>> list item as the first indicator of trouble... but I could be wrong.
>>>
>>> I think you said you could reproduce it, right?  So certainly worth
>>> testing with this fix I suppose.
>> Yeah, we're working on doing that now.  We're not running with a lot of
>> debugging turned on so we may or may not actually fall over if we try to
>> traverse freed (or just wrong) list entries.  If it isn't the same race,
>> though, then there's still one lurking in this code and that would be a
>> hell of a coincidence.
> 
> FYI we're running now with this patch in both a test and a production
> environment and haven't (yet) seen the bitmap inconsistency we were
> encountering regularly.  So far we have over 18 hours of runtime.  So,
> despite the enormous coincidence, our problem appears to be due to the
> same cause.
> 
> Thanks for the fix, Eric!

Good deal; I'll just trust that it's fixed, and maybe at some point I'll
sort out how they're related ;)

Thanks,
-Eric
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