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Date: Wed, 1 Jul 2009 10:56:12 +0200
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [Qemu-devel] [PATCH] block-raw: Allow pread beyond the end of
	growable images
Message-ID: <20090701085612.GA3564@lst.de>
References: <1246038684-3702-1-git-send-email-kwolf@redhat.com>
	<20090630180940.GA4205@lst.de> <4A4B1238.8060302@redhat.com>
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org

On Wed, Jul 01, 2009 at 09:37:28AM +0200, Kevin Wolf wrote:
> If you feel like posting a better patch, go ahead. I'm feeling that it's
> going to be a whole lot uglier in bdrv_pwrite, but that might prove
> wrong. And after all it is a problem with raw and not with the generic
> block code - qcow2 for example was already reading zeros.
> 
> For the time being, this patch fixes a bug and should stay.

So the only use case is a doing a savevm on a qcow2 device with a
raw-posix backing dev?  What happens with nbd backing dev or a raw
backing dev on win32?  OR (not sure we'll actually support that) another
image format backing dev?