From nobody Sun Oct 5 20:54:05 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1499290147583786.219987576407; Wed, 5 Jul 2017 14:29:07 -0700 (PDT) Received: from localhost ([::1]:48166 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dSrr7-0006h0-9D for importer@patchew.org; Wed, 05 Jul 2017 17:29:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38234) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dSrYF-0005HN-Gq for qemu-devel@nongnu.org; Wed, 05 Jul 2017 17:09:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dSrYE-0002sj-II for qemu-devel@nongnu.org; Wed, 05 Jul 2017 17:09:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49386) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dSrY7-0002q5-MO; Wed, 05 Jul 2017 17:09:27 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B81BB267C9; Wed, 5 Jul 2017 21:09:26 +0000 (UTC) Received: from red.redhat.com (ovpn-120-36.rdu2.redhat.com [10.10.120.36]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8EB82600CC; Wed, 5 Jul 2017 21:09:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B81BB267C9 Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=eblake@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B81BB267C9 From: Eric Blake To: qemu-devel@nongnu.org Date: Wed, 5 Jul 2017 16:08:41 -0500 Message-Id: <20170705210842.960-21-eblake@redhat.com> In-Reply-To: <20170705210842.960-1-eblake@redhat.com> References: <20170705210842.960-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Wed, 05 Jul 2017 21:09:26 +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 20/21] block: Minimize raw use of bds->total_sectors 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, Fam Zheng , qemu-block@nongnu.org, jcody@redhat.com, Max Reitz , Stefan Hajnoczi , jsnow@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" bdrv_is_allocated_above() was relying on intermediate->total_sectors, which is a field that can have stale contents depending on the value of intermediate->has_variable_length. An audit shows that we are safe (we were first calling through bdrv_co_get_block_status() which in turn calls bdrv_nb_sectors() and therefore just refreshed the current length), but it's nicer to favor our accessor functions to avoid having to repeat such an audit, even if it means refresh_total_sectors() is called more frequently. Suggested-by: John Snow Signed-off-by: Eric Blake Reviewed-by: Manos Pitsidianakis Reviewed-by: Jeff Cody Reviewed-by: John Snow --- v3-v4: no change v2: new patch --- block/io.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/io.c b/block/io.c index cb40069..fb8d1c7 100644 --- a/block/io.c +++ b/block/io.c @@ -1952,6 +1952,7 @@ int bdrv_is_allocated_above(BlockDriverState *top, intermediate =3D top; while (intermediate && intermediate !=3D base) { int64_t pnum_inter; + int64_t size_inter; int psectors_inter; ret =3D bdrv_is_allocated(intermediate, sector_num * BDRV_SECTOR_S= IZE, @@ -1969,13 +1970,14 @@ int bdrv_is_allocated_above(BlockDriverState *top, /* * [sector_num, nb_sectors] is unallocated on top but intermediate - * might have - * - * [sector_num+x, nr_sectors] allocated. + * might have [sector_num+x, nb_sectors-x] allocated. */ + size_inter =3D bdrv_nb_sectors(intermediate); + if (size_inter < 0) { + return size_inter; + } if (n > psectors_inter && - (intermediate =3D=3D top || - sector_num + psectors_inter < intermediate->total_sectors)) { + (intermediate =3D=3D top || sector_num + psectors_inter < size= _inter)) { n =3D psectors_inter; } --=20 2.9.4