From patchwork Fri May 28 16:46:12 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 53920 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id BE96AB7D1B for ; Sat, 29 May 2010 03:05:19 +1000 (EST) Received: from localhost ([127.0.0.1]:41077 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OI2zk-0005AT-3t for incoming@patchwork.ozlabs.org; Fri, 28 May 2010 13:05:16 -0400 Received: from [140.186.70.92] (port=51340 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OI2i8-0007aK-5T for qemu-devel@nongnu.org; Fri, 28 May 2010 12:47:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OI2i6-0008Ks-VU for qemu-devel@nongnu.org; Fri, 28 May 2010 12:47:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60406) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OI2i6-0008Kg-Ov for qemu-devel@nongnu.org; Fri, 28 May 2010 12:47:02 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o4SGl0Gn026950 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 28 May 2010 12:47:01 -0400 Received: from localhost.localdomain (vpn1-4-101.ams2.redhat.com [10.36.4.101]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o4SGkTgi018145; Fri, 28 May 2010 12:46:59 -0400 From: Kevin Wolf To: anthony@codemonkey.ws Date: Fri, 28 May 2010 18:46:12 +0200 Message-Id: <1275065173-24045-14-git-send-email-kwolf@redhat.com> In-Reply-To: <1275065173-24045-1-git-send-email-kwolf@redhat.com> References: <1275065173-24045-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [Qemu-devel] [PATCH 13/14] qcow2: Fix corruption after error in update_refcount X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org After it is done with updating refcounts in the cache, update_refcount writes all changed entries to disk. If a refcount block allocation fails, however, there was no change yet and therefore first_index = last_index = -1. Don't treat -1 as a normal sector index (resulting in a 512 byte write!) but return without updating anything in this case. Signed-off-by: Kevin Wolf --- block/qcow2-refcount.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 5b7cda4..22b0b45 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -417,6 +417,10 @@ static int write_refcount_block_entries(BlockDriverState *bs, return 0; } + if (first_index < 0) { + return 0; + } + first_index &= ~(REFCOUNTS_PER_SECTOR - 1); last_index = (last_index + REFCOUNTS_PER_SECTOR) & ~(REFCOUNTS_PER_SECTOR - 1);