Message-ID: <4DD55364.8070002@oracle.com>
Date: Thu, 19 May 2011 10:29:08 -0700
From: Sunil Mushran <sunil.mushran@oracle.com>
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To: Christoph Hellwig <hch@lst.de>
CC: josef@redhat.com, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org,
        linux-ext4@vger.kernel.org, viro@ZenIV.linux.org.uk,
        ocfs2-devel@oss.oracle.com
Subject: Re: [Ocfs2-devel] [PATCH] ocfs2: Implement llseek()
References: <1305773084-19296-1-git-send-email-sunil.mushran@oracle.com> <1305773084-19296-3-git-send-email-sunil.mushran@oracle.com> <20110519110531.GB6357@lst.de>
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On 05/19/2011 04:05 AM, Christoph Hellwig wrote:
> On Wed, May 18, 2011 at 07:44:44PM -0700, Sunil Mushran wrote:
>> Unwritten (preallocated) extents are considered holes because the file system
>> treats reads to such regions in the same way as it does to holes.
> How does this work for the case of an unwrittent extent that has been
> written to in the pagecache but not converted yet?  Y'know the big data
> corruption and flamewar that started all this?

We don't delay splitting the extent. It is split in ->write_begin(). Delaying
it will be a challenge as we have to provide cache coherency across the
cluster.

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