From patchwork Tue Feb 14 19:25:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 727958 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 3vNC964B06z9s74 for ; Wed, 15 Feb 2017 06:27:06 +1100 (AEDT) Received: from localhost ([::1]:36769 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cdiki-0002E1-3j for incoming@patchwork.ozlabs.org; Tue, 14 Feb 2017 14:27:04 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39326) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cdijG-0000vM-Lf for qemu-devel@nongnu.org; Tue, 14 Feb 2017 14:25:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cdijF-0005Hr-8k for qemu-devel@nongnu.org; Tue, 14 Feb 2017 14:25:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54156) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cdijC-0005G5-BR; Tue, 14 Feb 2017 14:25:30 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (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 8617261E53; Tue, 14 Feb 2017 19:25:30 +0000 (UTC) Received: from red.redhat.com (ovpn-123-249.rdu2.redhat.com [10.10.123.249] (may be forged)) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1EJPQGT030393; Tue, 14 Feb 2017 14:25:29 -0500 From: Eric Blake To: qemu-devel@nongnu.org Date: Tue, 14 Feb 2017 13:25:19 -0600 Message-Id: <20170214192525.18624-2-eblake@redhat.com> In-Reply-To: <20170214192525.18624-1-eblake@redhat.com> References: <20170214192525.18624-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 14 Feb 2017 19:25:30 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v5 1/7] qcow2: Assert that cluster operations are aligned 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, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" qcow2_discard_clusters() is set up to silently ignore sub-cluster head or tail on unaligned requests. However, it is easy to audit the various callers: qcow2_snapshot_create() has always passed aligned data since the call was introduced in 1ebf561; qcow2_co_pdiscard() has passed aligned clusters since commit ecdbead taught the block layer the preferred discard alignment (the block layer can still pass sub-cluster values, but those are handled directly in qcow2_co_pdiscard()); and qcow2_make_empty() was fixed to pass aligned clusters in commit a3e1505. Replace rounding with assertions to hold us to the tighter contract, eliminating the now-impossible case of an early exit for a sub-cluster request. qcow2_zero_clusters() has always been called with cluster-aligned arguments from its lone caller qcow2_co_pwrite_zeroes() (like qcow2_co_pdiscard(), the caller takes care of sub-cluster requests from the block layer; and qcow2_zero_clusters() would have misbehaved on unaligned requests), but it deserves the same assertion for symmetry. Signed-off-by: Eric Blake Reviewed-by: Max Reitz --- v5: no change v4: new patch --- block/qcow2-cluster.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 928c1e2..3304a15 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1521,13 +1521,9 @@ int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS); - /* Round start up and end down */ - offset = align_offset(offset, s->cluster_size); - end_offset = start_of_cluster(s, end_offset); - - if (offset > end_offset) { - return 0; - } + /* Caller must pass aligned values */ + assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); + assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size)); nb_clusters = size_to_clusters(s, end_offset - offset); @@ -1602,6 +1598,10 @@ int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors, uint64_t nb_clusters; int ret; + /* Caller must pass aligned values */ + assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); + assert(QEMU_IS_ALIGNED(nb_sectors, s->cluster_size >> BDRV_SECTOR_BITS)); + /* The zero flag is only supported by version 3 and newer */ if (s->qcow_version < 3) { return -ENOTSUP;