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=-2.1 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 82D96C55193 for ; Thu, 23 Apr 2020 14:00:01 +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 4EE2A2077D for ; Thu, 23 Apr 2020 14:00:01 +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="N3XjhIu+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4EE2A2077D 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]:44002 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jRcOW-000613-Gm for qemu-devel@archiver.kernel.org; Thu, 23 Apr 2020 10:00:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50242) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jRcNu-0005WA-Uk for qemu-devel@nongnu.org; Thu, 23 Apr 2020 09:59:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jRcNt-0001h7-Q0 for qemu-devel@nongnu.org; Thu, 23 Apr 2020 09:59:22 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:47168 helo=us-smtp-delivery-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 1jRcNt-0001fy-9k for qemu-devel@nongnu.org; Thu, 23 Apr 2020 09:59:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587650360; 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=4ROI2zE1i8rjGCCkkDt9KX9co/8oUiXho6803pYH4Kw=; b=N3XjhIu+jv1ue+wm/VAFt+iOf/iGm7EUeLxuyAOOss+GlIzt/eITkW91MD0hOW/R5OZFo0 6ElesbCY4IIEKOi2FgANzUDzmiss7rrPr4ORFDyDUw6n1j6QP/FX2Ue5gdjDxlpEkbRdHp 0J3QaX7qtoQoaZh7hL6lvRA31EMtyww= 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-381-CtW6yGLsP-mrtZ-KFYo17g-1; Thu, 23 Apr 2020 09:59:16 -0400 X-MC-Unique: CtW6yGLsP-mrtZ-KFYo17g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 83D68460; Thu, 23 Apr 2020 13:59:15 +0000 (UTC) Received: from [10.10.116.80] (ovpn-116-80.rdu2.redhat.com [10.10.116.80]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5DFAD6084C; Thu, 23 Apr 2020 13:59:14 +0000 (UTC) Subject: Re: [PATCH v5 4/9] qcow2: Support BDRV_REQ_ZERO_WRITE for truncate To: Kevin Wolf References: <20200422152129.167074-1-kwolf@redhat.com> <20200422152129.167074-5-kwolf@redhat.com> <84c6ca49-aef3-adf4-2efe-68357dd20ce8@redhat.com> <20200422155835.GC7155@linux.fritz.box> <20d12788-2d62-12a4-0949-f29594054026@redhat.com> <20200423132302.GA23654@linux.fritz.box> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Thu, 23 Apr 2020 08:59:12 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200423132302.GA23654@linux.fritz.box> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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=207.211.31.81; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/23 02:14:02 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: vsementsov@virtuozzo.com, berto@igalia.com, qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/23/20 8:23 AM, Kevin Wolf wrote: >>> >>> So qcow2_cluster_zeroize() seems to accept the unaligned tail. It would >>> still set the zero flag for the partial last cluster and for the >>> external data file, bdrv_co_pwrite_zeroes() would have the correct size. >> >> Then I'm in favor of NOT rounding the tail. That's an easy enough change >> and we've now justified that it does what we want, so R-b stands with that >> one-line tweak. > > Would have been too easy... bs->total_sectors isn't updated yet, so the > assertion does fail. > > I can make the assertion check end_offset >= ... instead. That should > still check what we wanted to check here and allow the unaligned > extension. Yes, that works for me. > > This feels like the better option to me compared to updating > bs->total_sectors earlier and then undoing that change in every error > path. Indeed. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org