From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 393E5C3A5A2 for ; Fri, 20 Sep 2019 15:59:56 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 107B02086A for ; Fri, 20 Sep 2019 15:59:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 107B02086A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:32916 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iBLK6-0003Ba-Nn for qemu-devel@archiver.kernel.org; Fri, 20 Sep 2019 11:59:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43982) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iBKpo-0000ub-5Z for qemu-devel@nongnu.org; Fri, 20 Sep 2019 11:28:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iBKpl-0004W1-FK for qemu-devel@nongnu.org; Fri, 20 Sep 2019 11:28:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48784) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iBKpi-0004Uj-Of; Fri, 20 Sep 2019 11:28:30 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1643B18C890D; Fri, 20 Sep 2019 15:28:30 +0000 (UTC) Received: from localhost (unknown [10.40.205.102]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9C59A60606; Fri, 20 Sep 2019 15:28:29 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH 10/22] quorum: Implement .bdrv_recurse_can_replace() Date: Fri, 20 Sep 2019 17:27:52 +0200 Message-Id: <20190920152804.12875-11-mreitz@redhat.com> In-Reply-To: <20190920152804.12875-1-mreitz@redhat.com> References: <20190920152804.12875-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.70]); Fri, 20 Sep 2019 15:28:30 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Alberto Garcia , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Signed-off-by: Max Reitz --- block/quorum.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/block/quorum.c b/block/quorum.c index 207054a64e..81b57dbae2 100644 --- a/block/quorum.c +++ b/block/quorum.c @@ -825,6 +825,67 @@ static bool quorum_recurse_is_first_non_filter(Block= DriverState *bs, return false; } =20 +static bool quorum_recurse_can_replace(BlockDriverState *bs, + BlockDriverState *to_replace) +{ + BDRVQuorumState *s =3D bs->opaque; + int i; + + for (i =3D 0; i < s->num_children; i++) { + /* + * We have no idea whether our children show the same data as + * this node (@bs). It is actually highly likely that + * @to_replace does not, because replacing a broken child is + * one of the main use cases here. + * + * We do know that the new BDS will match @bs, so replacing + * any of our children by it will be safe. It cannot change + * the data this quorum node presents to its parents. + * + * However, replacing @to_replace by @bs in any of our + * children's chains may change visible data somewhere in + * there. We therefore cannot recurse down those chains with + * bdrv_recurse_can_replace(). + * (More formally, bdrv_recurse_can_replace() requires that + * @to_replace will be replaced by something matching the @bs + * passed to it. We cannot guarantee that.) + * + * Thus, we can only check whether any of our immediate + * children matches @to_replace. + * + * (In the future, we might add a function to recurse down a + * chain that checks that nothing there cares about a change + * in data from the respective child in question. For + * example, most filters do not care when their child's data + * suddenly changes, as long as their parents do not care.) + */ + if (s->children[i].child->bs =3D=3D to_replace) { + Error *local_err =3D NULL; + + /* + * We now have to ensure that there is no other parent + * that cares about replacing this child by a node with + * potentially different data. + */ + s->children[i].to_be_replaced =3D true; + bdrv_child_refresh_perms(bs, s->children[i].child, &local_er= r); + + /* Revert permissions */ + s->children[i].to_be_replaced =3D false; + bdrv_child_refresh_perms(bs, s->children[i].child, &error_ab= ort); + + if (local_err) { + error_free(local_err); + return false; + } + + return true; + } + } + + return false; +} + static int quorum_valid_threshold(int threshold, int num_children, Error= **errp) { =20 @@ -1195,6 +1256,7 @@ static BlockDriver bdrv_quorum =3D { =20 .is_filter =3D true, .bdrv_recurse_is_first_non_filter =3D quorum_recurse_is_first_non_= filter, + .bdrv_recurse_can_replace =3D quorum_recurse_can_replace, =20 .strong_runtime_opts =3D quorum_strong_runtime_opts, }; --=20 2.21.0