From nobody Thu Nov 13 13:37:42 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1580421374143679.4154350190648; Thu, 30 Jan 2020 13:56:14 -0800 (PST) Received: from localhost ([::1]:39878 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ixHnI-0005lC-Nz for importer@patchew.org; Thu, 30 Jan 2020 16:56:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33405) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ixHcW-0004xd-PU for qemu-devel@nongnu.org; Thu, 30 Jan 2020 16:45:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ixHcU-0004BZ-FQ for qemu-devel@nongnu.org; Thu, 30 Jan 2020 16:45:03 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:42073 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ixHcU-0004A4-AJ for qemu-devel@nongnu.org; Thu, 30 Jan 2020 16:45:02 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-256-eHk9S9_ONHazVFui3XAe4g-1; Thu, 30 Jan 2020 16:44:58 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3B98B800E21; Thu, 30 Jan 2020 21:44:57 +0000 (UTC) Received: from localhost (ovpn-204-145.brq.redhat.com [10.40.204.145]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C6BEB19756; Thu, 30 Jan 2020 21:44:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580420701; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=x/ebeROUpozO9G18Nn37Qclo1gAsS3p1IXwOd05lc8I=; b=LtoxdsnWH63ctD4RZwlbv4lExr6sjxIOBB7LIPI1M+1XgF5ySpd92R3uXl2R6zRlts7SX6 zJS5eoeIDxU7ZO7KQycLTomnpCZJKxhHs3yOE8J+ZzzQLkOqm6LwE4sKJXaNS5a+W38M/w WR7D0x88rhddcZk06gdP821PBkhl4Ls= From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 10/21] quorum: Implement .bdrv_recurse_can_replace() Date: Thu, 30 Jan 2020 22:44:20 +0100 Message-Id: <20200130214431.333510-11-mreitz@redhat.com> In-Reply-To: <20200130214431.333510-1-mreitz@redhat.com> References: <20200130214431.333510-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: eHk9S9_ONHazVFui3XAe4g-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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 , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Signed-off-by: Max Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/quorum.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/block/quorum.c b/block/quorum.c index 6a7224c9e4..22c1060b42 100644 --- a/block/quorum.c +++ b/block/quorum.c @@ -825,6 +825,62 @@ static bool quorum_recurse_is_first_non_filter(BlockDr= iverState *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) { + int ret; + + /* + * 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; + ret =3D bdrv_child_refresh_perms(bs, s->children[i].child, NUL= L); + + /* Revert permissions */ + s->children[i].to_be_replaced =3D false; + bdrv_child_refresh_perms(bs, s->children[i].child, &error_abor= t); + + return ret =3D=3D 0; + } + } + + return false; +} + static int quorum_valid_threshold(int threshold, int num_children, Error *= *errp) { =20 @@ -1197,6 +1253,7 @@ static BlockDriver bdrv_quorum =3D { =20 .is_filter =3D true, .bdrv_recurse_is_first_non_filter =3D quorum_recurse_is_first_non_fi= lter, + .bdrv_recurse_can_replace =3D quorum_recurse_can_replace, =20 .strong_runtime_opts =3D quorum_strong_runtime_opts, }; --=20 2.24.1