From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45493) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uzk2v-0001DA-KT for qemu-devel@nongnu.org; Thu, 18 Jul 2013 04:58:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uzk2u-00040f-Ri for qemu-devel@nongnu.org; Thu, 18 Jul 2013 04:58:45 -0400 Received: from mail-wi0-x234.google.com ([2a00:1450:400c:c05::234]:40460) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uzk2u-00040a-Jq for qemu-devel@nongnu.org; Thu, 18 Jul 2013 04:58:44 -0400 Received: by mail-wi0-f180.google.com with SMTP id c10so2923432wiw.1 for ; Thu, 18 Jul 2013 01:58:43 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <51E7AE38.2010305@redhat.com> Date: Thu, 18 Jul 2013 10:58:32 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1373992168-26043-1-git-send-email-pbonzini@redhat.com> <51E7A48E.5030606@kamp.de> In-Reply-To: <51E7A48E.5030606@kamp.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 00/17] Add qemu-img subcommand to dump file metadata List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: famz@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com Il 18/07/2013 10:17, Peter Lieven ha scritto: > > maybe i have missed it in your patches, but would it be also possible to issue > DISCARDZEROES ioctl on linux to return zero status for block devices also? I think that would belong in your patches. Once we have discard_zeroes, we can use it as you suggested. It is a good occasion to ask Linux developers for clarifications about the meaning of discard_zeroes in the presence of misaligned requests. But because of legacy, we might need to query the kernel for the granularity ourselves---which is ugly because it is not available through a ioctl, only sysfs. Paolo