From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55770) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VLWYz-0000sX-JT for qemu-devel@nongnu.org; Mon, 16 Sep 2013 07:01:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VLWYu-0001xu-K8 for qemu-devel@nongnu.org; Mon, 16 Sep 2013 07:01:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10232) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VLWYu-0001xo-AY for qemu-devel@nongnu.org; Mon, 16 Sep 2013 07:01:48 -0400 Message-ID: <5236E51E.8020807@redhat.com> Date: Mon, 16 Sep 2013 13:01:50 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1379067909-22984-1-git-send-email-pl@kamp.de> <1379067909-22984-9-git-send-email-pl@kamp.de> <5232EA90.7030903@redhat.com> <523358AF.9000504@redhat.com> <52336C21.2050902@kamp.de> In-Reply-To: <52336C21.2050902@kamp.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 08/12] qemu-img: conditionally zero out target on convert List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, anthony@codemonkey.ws, stefanha@redhat.com, qemu-devel@nongnu.org, ronniesahlberg@gmail.com Il 13/09/2013 21:48, Peter Lieven ha scritto: > Am 13.09.2013 20:25, schrieb Eric Blake: >> On 09/13/2013 04:36 AM, Paolo Bonzini wrote: >>> Il 13/09/2013 12:25, Peter Lieven ha scritto: >>>> if the target has_zero_init = 0, but supports efficiently >>>> writing zeroes by unmapping we call bdrv_zeroize to >>>> avoid fully allocating the target. this currently >>>> is designed especially for iscsi. >>>> >>>> Signed-off-by: Peter Lieven >>>> --- >>>> qemu-img.c | 22 ++++++++++++++++------ >>>> 1 file changed, 16 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/qemu-img.c b/qemu-img.c >>>> index 3e5e388..6eaddc6 100644 >>>> --- a/qemu-img.c >>>> +++ b/qemu-img.c >>>> @@ -1354,7 +1354,8 @@ static int img_convert(int argc, char **argv) >>>> } >>>> } >>>> >>>> - flags = BDRV_O_RDWR; >>>> + flags = BDRV_O_RDWR | BDRV_O_UNMAP; >>> I think this should be a new command-line flag. >> I agree - while 'sparse by default' may be reasonable, it is also >> feasible to want a mode that guarantees expansion rather than unmapped >> or sparse. >> > Ok, so do you find the proposed -S 0 bei Paolo a good choice? > If this is supplied I would go as far as completly setting > has_zero_init = 0 also for targets which default to 1. This > would guaranteed exspansion and full allocation for all drivers. Sounds good. Paolo