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Date: Tue, 08 Dec 2009 11:00:17 +0100
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH VERSION 2] Disk image shared and exclusive
	locks.
References: <20091204165301.GA4167@amd.home.annexia.org>
	<20091207141652.GA28705@amd.home.annexia.org>
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To: "Richard W.M. Jones" <rjones@redhat.com>
Cc: qemu-devel@nongnu.org

Am 07.12.2009 15:16, schrieb Richard W.M. Jones:
> Here's a second go at this patch.  The only change is that we add a
> second parameter (backinglock=none|shared|exclusive) which can be used
> to control locking on the first level (only) of backing disk.

And what about the backing file of the backing file? ;-) This approach
feels wrong somehow. We need to infer the locking for backing file from
the COW file (none => none; shared/exclusive => shared; commit acquires
an exclusive lock temporarily, but still can't prevent corruption with
turned off VMs)

You probably should add the locking flags to bdrv_open calls in
qemu-img, too.

Kevin