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 8AD30C43603 for ; Thu, 19 Dec 2019 10:14:09 +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 50C3C24650 for ; Thu, 19 Dec 2019 10:14:09 +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="LTspnsiF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50C3C24650 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]:38210 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihsoq-0006GN-F0 for qemu-devel@archiver.kernel.org; Thu, 19 Dec 2019 05:14:08 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:34804) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihso8-0005kr-UO for qemu-devel@nongnu.org; Thu, 19 Dec 2019 05:13:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ihso7-0001SO-Lq for qemu-devel@nongnu.org; Thu, 19 Dec 2019 05:13:24 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:40022 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ihso7-0001PP-Bv for qemu-devel@nongnu.org; Thu, 19 Dec 2019 05:13:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576750402; 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=6r6qCZ4FoFaBnAOZp/wJBwi8ZjX/D8NCa1+ofPxBKq4=; b=LTspnsiF2pxoCuNfHU0SKruOJY5H7pEGfH0yA1LQvGDodc2e013L6DP0vUHk2tmiM9fxFo v5bTriMO0HtoQE2LfhGtOIfGOFBJ/DlmUGyZmGLZCtkvMHbHv+IbmH1wuhENTydKxoKNlL pLXUJ1/vEcU6yiAYDEd6PydmJ9mXORI= 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-362-GDsH74wWPsS6nLOSiyLF6A-1; Thu, 19 Dec 2019 05:13:19 -0500 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 BA753800053; Thu, 19 Dec 2019 10:13:18 +0000 (UTC) Received: from linux.fritz.box (ovpn-117-53.ams2.redhat.com [10.36.117.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 210B65DA32; Thu, 19 Dec 2019 10:13:13 +0000 (UTC) Date: Thu, 19 Dec 2019 11:13:12 +0100 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH for-4.2? v3 0/8] block: Fix resize (extending) of short overlays Message-ID: <20191219101312.GD5230@linux.fritz.box> References: <20191122160511.8377-1-kwolf@redhat.com> <20191210174644.GC7103@linux.fritz.box> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-MC-Unique: GDsH74wWPsS6nLOSiyLF6A-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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: "qemu-devel@nongnu.org" , "stefanha@redhat.com" , "qemu-block@nongnu.org" , "mreitz@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 19.12.2019 um 10:24 hat Vladimir Sementsov-Ogievskiy geschrieben: > 10.12.2019 20:46, Kevin Wolf wrote: > > Am 22.11.2019 um 17:05 hat Kevin Wolf geschrieben: > >> See patch 4 for the description of the bug fixed. > >=20 > > I'm applying patches 3 and 5-7 to the block branch because they make > > sense on their own. > >=20 > > The real fix will need another approach because the error handling is > > broken in this one: If zeroing out fails (either because of NO_FALLBACK > > or because of some other I/O error), bdrv_co_truncate() will return > > failure, but the image size has already been increased, with potentiall= y > > incorrect data in the new area. > >=20 > > To fix this, we need to make sure that zeros will be read before we > > commit the new image size to the image file (e.g. qcow2 header) and to > > bs->total_sectors. In other words, it must become the responsibility of > > the block driver. > >=20 > > To this effect, I'm planning to introduce a PREALLOC_MODE_ZERO_INIT fla= g > > that can be or'ed to the preallocation mode. This will fail by default > > because it looks like just another unimplemented preallocation mode to > > block drivers. It will be requested explicitly by commit jobs and > > automatically added by bdrv_co_truncate() if the backing file would > > become visible (like in this series, but now for all preallocation > > modes). I'm planning to implement it for qcow2 and file-posix for now, > > which should cover most interesting cases. > >=20 > > Does this make sense to you? >=20 > This should work. Do you still have this plan in a timeline? Still planning to do this, but tomorrow is my last working day for this year. So I guess I'll get to it sometime in January. Kevin