From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:54206)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1VCR6m-0004ZJ-6y
	for qemu-devel@nongnu.org; Thu, 22 Aug 2013 05:23:19 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1VCR6g-0005bO-8Z
	for qemu-devel@nongnu.org; Thu, 22 Aug 2013 05:23:12 -0400
Received: from mx1.redhat.com ([209.132.183.28]:34658)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1VCR6g-0005bI-0Y
	for qemu-devel@nongnu.org; Thu, 22 Aug 2013 05:23:06 -0400
Message-ID: <5215D84D.2010005@redhat.com>
Date: Thu, 22 Aug 2013 11:22:21 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1375071932-31627-1-git-send-email-famz@redhat.com>
	<1375071932-31627-4-git-send-email-famz@redhat.com>
	<20130821130203.GB11975@stefanha-thinkpad.redhat.com>
	<20130822085320.GA14691@T430s.nay.redhat.com>
In-Reply-To: <20130822085320.GA14691@T430s.nay.redhat.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [RFC PATCH 3/4] qmp: Add "snapshot=" option to
	nbd-server-add
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: famz@redhat.com
Cc: kwolf@redhat.com, Stefan Hajnoczi <stefanha@gmail.com>, imain@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com

Il 22/08/2013 10:53, Fam Zheng ha scritto:
>> > This is handy but only works if the QEMU process has permission to
>> > create temporary files.
>> > 
> Yes, this is a shortcut, it has this limitation, but the good side is
> it's easy to get and no other dependency.
> 
> To avoid creating file, we'll need blockdev-add to override backing_hd,
> and blockdev-backup to use an existing BDS as target, then we simply use
> current nbd-server-add to export it.
> 
> This series is still RFC, with above said, we still need to decide which
> is the way we (QEMU and libvirt) want for 1.7.  any thoughts?

I think this was the initial design, but Kevin already said he didn't
like the idea.

(Also, if you do this you have to add nbd-server-add to qmp-transaction,
to atomically start fleecing of multiple devices).

Paolo