From patchwork Tue Dec 20 19:15:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 9482109 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 46AB6606DB for ; Tue, 20 Dec 2016 19:16:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3B99E2832F for ; Tue, 20 Dec 2016 19:16:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2E5BC2836D; Tue, 20 Dec 2016 19:16:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id D0D962832F for ; Tue, 20 Dec 2016 19:16:09 +0000 (UTC) Received: from localhost ([::1]:53073 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cJPtQ-000821-Rz for patchwork-qemu-devel@patchwork.kernel.org; Tue, 20 Dec 2016 14:16:08 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57558) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cJPsq-0007tg-Ix for qemu-devel@nongnu.org; Tue, 20 Dec 2016 14:15:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cJPsp-0007LH-K7 for qemu-devel@nongnu.org; Tue, 20 Dec 2016 14:15:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50648) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cJPsl-0007Hv-BW; Tue, 20 Dec 2016 14:15:27 -0500 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 91D2BC075659; Tue, 20 Dec 2016 19:15:26 +0000 (UTC) Received: from red.redhat.com (ovpn-117-53.rdu2.redhat.com [10.10.117.53]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uBKJFNIf004510; Tue, 20 Dec 2016 14:15:25 -0500 From: Eric Blake To: qemu-devel@nongnu.org Date: Tue, 20 Dec 2016 13:15:17 -0600 Message-Id: <20161220191523.5779-2-eblake@redhat.com> In-Reply-To: <20161220191523.5779-1-eblake@redhat.com> References: <20161220191523.5779-1-eblake@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 [10.5.110.32]); Tue, 20 Dec 2016 19:15:26 +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 v4 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: Kevin Wolf , "open list:qcow2" , Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP 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 --- 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;