From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:57387)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1UzYMH-0000L3-RQ
	for qemu-devel@nongnu.org; Wed, 17 Jul 2013 16:29:58 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1UzYMG-0004gH-RW
	for qemu-devel@nongnu.org; Wed, 17 Jul 2013 16:29:57 -0400
Received: from mx1.redhat.com ([209.132.183.28]:7874)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1UzYMG-0004g7-KZ
	for qemu-devel@nongnu.org; Wed, 17 Jul 2013 16:29:56 -0400
Message-ID: <51E6F7C3.7070000@redhat.com>
Date: Wed, 17 Jul 2013 22:00:03 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1373885375-13601-1-git-send-email-pl@kamp.de>
	<1373885375-13601-5-git-send-email-pl@kamp.de>
	<20130717084648.GD2458@dhcp-200-207.str.redhat.com>
	<51E66ACD.70706@redhat.com>
	<20130717102551.GF2458@dhcp-200-207.str.redhat.com>
	<CAN05THSiKdxONhHboG5a43KSeAZGnpq9=-T1YAKNipPQccDjww@mail.gmail.com>
	<51E6C5FC.1030304@redhat.com>
	<CAN05THSiLVt-cWq8x26Z6kdsAw0tvGf6zMDeJD8tVmZ=jCTSQQ@mail.gmail.com>
	<7C1EEB41-E2B3-4186-9188-379F02E76FF9@kamp.de>
	<51E6CE81.6000400@redhat.com>
	<36C25446-54C7-4D1F-9D8D-E8A3991489BD@kamp.de>
In-Reply-To: <36C25446-54C7-4D1F-9D8D-E8A3991489BD@kamp.de>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target
	on convert
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: Peter Lieven <pl@kamp.de>
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, ronnie sahlberg <ronniesahlberg@gmail.com>

Il 17/07/2013 19:48, Peter Lieven ha scritto:
> 
> Am 17.07.2013 um 19:04 schrieb Paolo Bonzini <pbonzini@redhat.com>:
> 
>> Il 17/07/2013 19:02, Peter Lieven ha scritto:
>>> For Disks we always use read/write16 so i think we Should also use writesame16. Or not?
>>
>> Yes.
>>
>> Remember you can still use UNMAP if LBPRZ=0.
> 
> I can always use it if writesame is not available, but in this case bdi->discard_zeroes must be 0.
> 
> Maybe we should call it discard_writes_zeroes or similar.
> 
> Discard_zeroes is sth that should only indicate if lbprz == 1. At
> least if we refer to the Linux ioctl. We could include both in BDI.

I don't know... I don't see the usefulness of
discard_zeroes_part_of_what_it_was_told_to... :)

Paolo