From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0ADC8C433DF for ; Wed, 10 Jun 2020 15:50:30 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CA67F206F4 for ; Wed, 10 Jun 2020 15:50:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fEbdxyWA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA67F206F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53856 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jj2zk-0007U0-Pd for qemu-devel@archiver.kernel.org; Wed, 10 Jun 2020 11:50:28 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53130) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jj2yO-0006Ri-Cb for qemu-devel@nongnu.org; Wed, 10 Jun 2020 11:49:04 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:25535 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jj2yM-0002oZ-UZ for qemu-devel@nongnu.org; Wed, 10 Jun 2020 11:49:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591804141; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QS7LQOJ0sinqPq2qZ20ZFJ6Ee7GUjyYhLkAuap82+2k=; b=fEbdxyWA1XU+BH3+GIfvcvDmun3F7jhsDwIXKeQTmBCkeMIA6zjCmQ4PWIczIYPjiR1IZQ J3B5q0j58s1kuGdmvKZ+bP8MpBdecIr99OpadOrRo/YM1KDGZC+pcsRnyJsES5mTCElX74 8kgetv32xNNgPqVL2RnpXbkjrD2GJcg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-102-T2jIxRmDPXWhpVX2Y4IxIg-1; Wed, 10 Jun 2020 11:48:54 -0400 X-MC-Unique: T2jIxRmDPXWhpVX2Y4IxIg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 841D3800053; Wed, 10 Jun 2020 15:48:53 +0000 (UTC) Received: from [10.3.113.22] (ovpn-113-22.phx2.redhat.com [10.3.113.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A292A5D9D3; Wed, 10 Jun 2020 15:48:52 +0000 (UTC) Subject: Re: Clarification regarding new qemu-img convert --target-is-zero flag To: David Edmondson , Sam Eiderman , Kevin Wolf References: <20200610140620.GE6947@linux.fritz.box> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <999a1a74-d082-bcdb-e3f9-6c44b2526433@redhat.com> Date: Wed, 10 Jun 2020 10:48:52 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/09 23:51:15 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tony Zhang , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 6/10/20 10:42 AM, David Edmondson wrote: > On Wednesday, 2020-06-10 at 18:29:33 +03, Sam Eiderman wrote: > >> Excuse me, >> >> Vladimir already pointed out in the first comment that it will skip >> writing real zeroes later. > > Right. That's why you want something like "--no-need-to-zero-initialise" > (the name keeps getting longer!), which would still write zeroes to the > blocks that should contain zeroes, as opposed to writing zeroes to > prepare the device. Or maybe something like: qemu-img convert --skip-unallocated which says that a pre-zeroing pass may be attempted, but it if fails, only the explicit zeroes need to be written rather than zeroes for all unallocated areas in the source (so the resulting image will NOT be an identical copy if there were any unallocated areas, but that the user is okay with that). -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org