linux-ext4 - Re: A warning from 3.6+ with bigalloc and delalloc when running xfstest

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Date:	Wed, 10 Oct 2012 13:02:52 -0400
From:	Andrey Sidorov <qrxd43@...orola.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: A warning from 3.6+ with bigalloc and delalloc when running xfstest

On Tue, Oct 9, 2012 at 9:51 AM, Theodore Ts'o <tytso@....edu> wrote:

> It is indeed, something we need to fix, and it's part of the problem
> where where the delayed allocation for bigalloc is completely screwed
> up.  Part of the problem is when we write into a cluster which has not
> yet been mapped in the extent tree, but which might (or might not)
> have had other blocks in the cluster that have already been subject to
> delayed allocation, we don't know whether to reserve clusters for the
> purposes of doing the the delayed allocation accounting.  Fixing this
> w/o the extent status tree means having to search the page cache and
> for other pages in the cluster, which is not only painful, but tricky
> from the perspective of lock ordering.
>
> Unfortunately, I didn't notice this problem originally because I
> hadn't been doing regular xfstests runs with bigalloc, and most of my
> testing had been with direct I/O, where these issues didn't come up.
>
>                                 - Ted

Hi Ted,

Does it mean I'd better turn off delalloc if I use bigalloc with linux 3.5.3?

Regards,
Andrey.
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