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Date: Mon, 1 Feb 2010 10:06:49 +0100
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [Qemu-devel] Re: [PATCH] block: Enable fall-back to read-only for
	backing file
Message-ID: <20100201090649.GA20918@lst.de>
References: <4B65B4B7.2030700@redhat.com> <4B6694C8.4010703@redhat.com>
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Naphtali Sprei <nsprei@redhat.com>, qemu-devel@nongnu.org, Sheng Yang <sheng@linux.intel.com>

On Mon, Feb 01, 2010 at 09:46:00AM +0100, Kevin Wolf wrote:
> > Is it better to always open the backing file with read-only mode ? this will be more consistent/predictable ?
> 
> I would love to open them read-only unconditionally, but we can't. It
> would break the commit monitor command. I think the read-only fallback
> is appropriate for backing files.

The clean way would be to require an explicit BACKING_WRITEABLE flag
if we want to commit to it.  But I suspect it's too late to refit that
now.