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Date: Fri, 6 May 2011 14:24:37 +0100
Message-ID: <BANLkTi=aTzPmHina=GNMXerMPQ+rXFdPjg@mail.gmail.com>
From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 3/8] qed: add support for Copy-on-Read
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, qemu-devel@nongnu.org

On Fri, Apr 29, 2011 at 1:14 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 27.04.2011 15:27, schrieb Stefan Hajnoczi:
>> From: Anthony Liguori <aliguori@us.ibm.com>
>>
>> When creating an image using qemu-img, just pass '-o copy_on_read' and then
>> whenever QED reads from a backing file, it will write the block to the QED
>> file after the read completes ensuring that you only fetch from the backing
>> device once.
>
> As discussed previously, this is not the right primary interface.
>
> Also, the patch still seems to be broken with respect to concurrent writes.

Both good points, I really wanted to give a full RFC patch series to
show all the code that has been written today.  But your points need
to be addressed for the next version.

Stefan