From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753201Ab1GVIas (ORCPT ); Fri, 22 Jul 2011 04:30:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64025 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752765Ab1GVIar (ORCPT ); Fri, 22 Jul 2011 04:30:47 -0400 Message-ID: <4E2935DD.20005@redhat.com> Date: Fri, 22 Jul 2011 10:33:33 +0200 From: Kevin Wolf User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110621 Fedora/3.1.11-1.fc15 Thunderbird/3.1.11 MIME-Version: 1.0 To: Pekka Enberg CC: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, levinsasha928@gmail.com, tglx@linutronix.de, linux-tip-commits@vger.kernel.org, kvm-devel Subject: Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption References: <4E27DEA9.20404@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 22.07.2011 10:21, schrieb Pekka Enberg: > On Thu, 21 Jul 2011, Kevin Wolf wrote: >> Hm, I must have missed this patch on the KVM mailing list... > > It wasn't on the list, sorry. > >> You should also error out before creating a new L2 table as its refcount >> would have to be updated, too. On the other hand, the patch is a bit too >> restrictive, because it applies the check to qcow1 which doesn't even >> have a refcount table. > > Oh, right, I broken QCOW1. > >> I'm not sure if everyone is aware of it, so another hint: Now that you >> can't grow qcow2 any more, you might find it useful to use qemu-img >> create -f qcow2 -o preallocation=metadata, so that all clusters are >> already present and you don't get random failures. > > Yup, I'm aware that you can't grow images anymore. The patch was meant as > a stop-gap measure while I'm hacking on refcount table support. Yeah, I was pretty sure you were aware of _that_, but maybe not everyone knows that metadata preallocation exists. Kevin