From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39556) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKRoL-0005CN-6j for qemu-devel@nongnu.org; Fri, 13 Sep 2013 07:45:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VKRoF-0008Dq-6X for qemu-devel@nongnu.org; Fri, 13 Sep 2013 07:45:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44216) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKRoE-0008Dh-UP for qemu-devel@nongnu.org; Fri, 13 Sep 2013 07:45:11 -0400 Message-ID: <5232FAC7.7030001@redhat.com> Date: Fri, 13 Sep 2013 13:45:11 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1379067909-22984-1-git-send-email-pl@kamp.de> <1379067909-22984-6-git-send-email-pl@kamp.de> <5232EA41.3030607@redhat.com> <5232EC9C.2060301@kamp.de> In-Reply-To: <5232EC9C.2060301@kamp.de> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 05/12] block: add logical block provisioning information to BlockDriverInfo List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, ronniesahlberg@gmail.com, stefanha@redhat.com, qemu-devel@nongnu.org, anthony@codemonkey.ws Il 13/09/2013 12:44, Peter Lieven ha scritto: > On 13.09.2013 12:34, Paolo Bonzini wrote: >> Il 13/09/2013 12:25, Peter Lieven ha scritto: >>> + /* maximum number of sectors that can be discarded at once */ >>> + int max_discard; >>> + /* maximum number of sectors that can zeroized at once */ >>> + int max_write_zeroes; >> These should not be needed outside the driver. >> >> If you want to make them private between block.c and block/iscsi.c, you >> can add them to BlockDriverState. > The question is, if the discard_zeroes or discard_write_zeroes is needed > outside the driver as well? > > I can put the max_* information in the block driver state. I also thought > to add alignment and granularity information even if they are currently > not yet used. Yeah, in fact bdrv_write_zeroes and bdrv_discard can be taught to split requests according to these parameters instead of introducing a new function bdrv_zeroize. You don't need bdrv_zeroize I think; you can simply use bdrv_write_zeroes. This is why I don't like this information in BlockDriverInfo. On the contrary, discard_write_zeroes is useful to "generic" clients, and your qemu-img patch shows why. Discard_zeroes is somewhere in the middle. You only use it in bdrv_get_block_status, but it is not something that should be hidden to users of the high-level block.c API. So it is fine to leave it in BlockDriverInfo. Paolo