From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:53787)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <stefanha@redhat.com>) id 1Uf9EM-0007To-Ma
	for qemu-devel@nongnu.org; Wed, 22 May 2013 09:37:33 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <stefanha@redhat.com>) id 1Uf9EJ-0006LG-7D
	for qemu-devel@nongnu.org; Wed, 22 May 2013 09:37:26 -0400
Received: from mx1.redhat.com ([209.132.183.28]:13649)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <stefanha@redhat.com>) id 1Uf9EI-0006L5-Vg
	for qemu-devel@nongnu.org; Wed, 22 May 2013 09:37:23 -0400
Date: Wed, 22 May 2013 15:37:16 +0200
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20130522133716.GA28600@stefanha-thinkpad.redhat.com>
References: <1368628476-19622-1-git-send-email-stefanha@redhat.com>
	<1368628476-19622-3-git-send-email-stefanha@redhat.com>
	<519A095D.4070808@redhat.com>
	<20130521133428.GA6631@stefanha-thinkpad.muc.redhat.com>
	<519B8EBD.6030006@redhat.com>
	<24E144B8C0207547AD09C467A8259F7558598A21@lisa.maurer-it.com>
	<519BA4EF.1000302@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <519BA4EF.1000302@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v3 2/8] block: add basic backup support to
 block driver
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: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "xiawenc@linux.vnet.ibm.com" <xiawenc@linux.vnet.ibm.com>, "imain@redhat.com" <imain@redhat.com>, Dietmar Maurer <dietmar@proxmox.com>

On Tue, May 21, 2013 at 06:46:39PM +0200, Paolo Bonzini wrote:
> Il 21/05/2013 18:26, Dietmar Maurer ha scritto:
> >> Hmm, right.  But do we need the bitmap at all?  We can just use
> >> > bdrv_is_allocated like bdrv_co_do_readv does.
> > Does that works with a nbd driver?
> 
> Ah, right.  That's the answer.

Yes, the target may not supported allocation info.

> > Or does that add another RPC call (slow down)?
> 
> It doesn't work at all.  Thus Stefan's patch is fine (except if you
> don't use HBitmapIter, there's no advantage in using HBitmap; you can
> use qemu/bitmap.h instead).

I chose HBitmap because bitmap.h uses the int type instead of uint64_t,
which makes it risky to use in the block layer.

Stefan