From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=55636 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1OvuV9-0004SE-3j
	for qemu-devel@nongnu.org; Wed, 15 Sep 2010 12:06:33 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69)
	(envelope-from <quintela@redhat.com>) id 1OvuV6-0004IE-Hw
	for qemu-devel@nongnu.org; Wed, 15 Sep 2010 12:06:25 -0400
Received: from mx1.redhat.com ([209.132.183.28]:4395)
	by eggs.gnu.org with esmtp (Exim 4.69)
	(envelope-from <quintela@redhat.com>) id 1OvuV6-0004I4-Bq
	for qemu-devel@nongnu.org; Wed, 15 Sep 2010 12:06:24 -0400
From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <4C8DDF18.5030703@redhat.com> (Kevin Wolf's message of "Mon, 13
	Sep 2010 10:21:44 +0200")
References: <1284213896-12705-1-git-send-email-aliguori@us.ibm.com>
	<1284213896-12705-2-git-send-email-aliguori@us.ibm.com>
	<4C8DDF18.5030703@redhat.com>
Date: Wed, 15 Sep 2010 18:03:48 +0200
Message-ID: <m3pqwf9eor.fsf@trasno.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Subject: [Qemu-devel] Re: [PATCH 1/3] block: allow migration to work with
	image files
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/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: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Kevin Wolf <kwolf@redhat.com> wrote:
> Am 11.09.2010 16:04, schrieb Anthony Liguori:

> There is a simple generic implementation:
>
> drv = bs->drv;
> drv->close(bs);
> drv->open(bs, bs->open_flags);
>
> Note that this only reopens e.g. the qcow2 layer, but not the image
> file, which is bs->file.
>
> This works for all simple case, that is, one format on top of one or
> more protocols, where the protocols don't need invalidation. I think
> this includes everything that is possible today. With -blockdev we might
> need to revise this to include the lower layers, too. (But only
> sometimes, because we don't want to reopen the file)

we require it for nfs consistency.  We need to:

source: fsync()
target: open() (after the fsync).

About your 1st comment, I am doing:

bdrv_close(bdrv);
bdrv_open(bdrv);

Do you mean that this don't close and open again the file with qcow2?

Later, Juan.