From patchwork Tue May 17 16:51:01 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 623214 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3r8NgT5pH5z9sf6 for ; Wed, 18 May 2016 02:53:09 +1000 (AEST) Received: from localhost ([::1]:51572 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2iF1-0001Kb-Uf for incoming@patchwork.ozlabs.org; Tue, 17 May 2016 12:53:07 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43629) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2iDH-0006Z9-5a for qemu-devel@nongnu.org; Tue, 17 May 2016 12:51:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b2iDF-0007GG-3l for qemu-devel@nongnu.org; Tue, 17 May 2016 12:51:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34991) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2iD8-0007Er-Ro; Tue, 17 May 2016 12:51:10 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2DEFB15568; Tue, 17 May 2016 16:51:10 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-35.ams2.redhat.com [10.36.116.35]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u4HGp6bM003047; Tue, 17 May 2016 12:51:08 -0400 From: Kevin Wolf To: qemu-block@nongnu.org Date: Tue, 17 May 2016 18:51:01 +0200 Message-Id: <1463503863-19009-2-git-send-email-kwolf@redhat.com> In-Reply-To: <1463503863-19009-1-git-send-email-kwolf@redhat.com> References: <1463503863-19009-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 17 May 2016 16:51:10 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 1/3] qcow2: fix condition in is_zero_cluster X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, den@openvz.org, qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: "Denis V. Lunev" We should check for (res & BDRV_BLOCK_ZERO) only. The situation when we will have !(res & BDRV_BLOCK_DATA) and will not have BDRV_BLOCK_ZERO is not possible for images with bdi.unallocated_blocks_are_zero == true. For those images where it's false, however, it can happen and we must not consider the data zeroed then or we would corrupt the image. Signed-off-by: Denis V. Lunev CC: Kevin Wolf Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block/qcow2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index 62febfc..a6012dc 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2412,7 +2412,7 @@ static bool is_zero_cluster(BlockDriverState *bs, int64_t start) BlockDriverState *file; int64_t res = bdrv_get_block_status_above(bs, NULL, start, s->cluster_sectors, &nr, &file); - return res >= 0 && ((res & BDRV_BLOCK_ZERO) || !(res & BDRV_BLOCK_DATA)); + return res >= 0 && (res & BDRV_BLOCK_ZERO); } static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start)