From patchwork Thu Jun 10 12:05:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Sementsov-Ogievskiy X-Patchwork-Id: 1490466 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=virtuozzo.com header.i=@virtuozzo.com header.a=rsa-sha256 header.s=selector2 header.b=sCS6nrri; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 4G12lP6y89z9sXG for ; Thu, 10 Jun 2021 22:06:57 +1000 (AEST) Received: from localhost ([::1]:42394 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lrJSZ-0002iK-Rh for incoming@patchwork.ozlabs.org; Thu, 10 Jun 2021 08:06:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39592) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lrJRu-0002BQ-Ij; Thu, 10 Jun 2021 08:06:15 -0400 Received: from mail-eopbgr80090.outbound.protection.outlook.com ([40.107.8.90]:15424 helo=EUR04-VI1-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lrJRs-0004Nw-RD; Thu, 10 Jun 2021 08:06:14 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=FpgtGQMOilFvtYLnZ24nzozd5CHtxBjHctmPgAXCyqLJyGpQcvzISx+OQu0yKj1dNJPHhlRDIPzsACvVxwtiAHpC2K+BJ7Aavsz3eat1PkDMckfs6SmJBe/0FAIaFZ9ucGbCvehw+GQ76aYR6KUwPkQc1Ogio3zXNVT5gbqa4LJwv6Y5tjPqtdrfqhFxcvPsR60LbmaeUhfiXFOZ48u2gmXrj2yISATVdRNYOHMbvxHvNIVsJT0QrowJLMi6Jk2xcnI9tds2Go+YWaZISR4nTj0lxGrxHo8xGufYFVfiwS5B83tdVGlr3s9AwBMD2zqo4sc/RuRFIVWQadv0vsyDJA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=+K6v85Em6NlHRpNUMJVT92lfLPbH5vPdbKcny2F2KZc=; b=obkI6C8tNFOqh1c9BCVOnkGRd9Yh1RMGMROCuozd4y0kDNiQCD/BJVhfh5CEg3oLQTmM2rTM0giA5sudilpoKyPM54nTK9N2JCD6Zzwoqh6zGCvx6wo5nIAYb/I5biYQ6WvmKJ0ksDmZmtsgn7w4gd6Pbt4JwkJhhFp0tKZ6YWtEN0mdfnZ6LrgEPZVSixaRH1CEB609ey589NR6EeEvyup9e3x2v0CtTgQJIxANdhVjZ7zNsZ9jf74tOhaSXcD9vFqtRCZEh6TPc1mLikrjiO1ipVW7SQJrK+YVQTQA8d8I3rmi2dqbFssHxlktzGdUVOBeAk0H8RQL56nwaaDvrA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=virtuozzo.com; dmarc=pass action=none header.from=virtuozzo.com; dkim=pass header.d=virtuozzo.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=virtuozzo.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=+K6v85Em6NlHRpNUMJVT92lfLPbH5vPdbKcny2F2KZc=; b=sCS6nrriSf+wpicz8iyHeXnJF/glKOTkOCnTHuiMEs8cXBGvFR4MvJ8jWg3U/MYzjjbqUpJyVMgAijTx5g7AsEdhaf9NDed2ijGcr6aWhQyfvoP6xHVtqp6Fh26DxjYQvWg/8649vGoIYIHDzu90QJFVpRebHNbeITtlGPRv0Ks= Authentication-Results: nongnu.org; dkim=none (message not signed) header.d=none;nongnu.org; dmarc=none action=none header.from=virtuozzo.com; Received: from AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) by AM6PR08MB4277.eurprd08.prod.outlook.com (2603:10a6:20b:bd::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4219.20; Thu, 10 Jun 2021 12:05:58 +0000 Received: from AM7PR08MB5494.eurprd08.prod.outlook.com ([fe80::f928:f4f2:77c0:74b4]) by AM7PR08MB5494.eurprd08.prod.outlook.com ([fe80::f928:f4f2:77c0:74b4%9]) with mapi id 15.20.4195.030; Thu, 10 Jun 2021 12:05:58 +0000 From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, mreitz@redhat.com, kwolf@redhat.com, berto@igalia.com, vsementsov@virtuozzo.com Subject: [PATCH v6 5/9] block: bdrv_reopen_parse_backing(): simplify handling implicit filters Date: Thu, 10 Jun 2021 15:05:33 +0300 Message-Id: <20210610120537.196183-6-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210610120537.196183-1-vsementsov@virtuozzo.com> References: <20210610120537.196183-1-vsementsov@virtuozzo.com> X-Originating-IP: [185.215.60.215] X-ClientProxiedBy: HE1PR0802CA0005.eurprd08.prod.outlook.com (2603:10a6:3:bd::15) To AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from localhost.localdomain (185.215.60.215) by HE1PR0802CA0005.eurprd08.prod.outlook.com (2603:10a6:3:bd::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4219.20 via Frontend Transport; Thu, 10 Jun 2021 12:05:57 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 931ff29c-9b34-44c0-94c1-08d92c081b38 X-MS-TrafficTypeDiagnostic: AM6PR08MB4277: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:243; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:AM7PR08MB5494.eurprd08.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(39840400004)(346002)(366004)(376002)(396003)(136003)(956004)(6486002)(2616005)(6916009)(6666004)(186003)(478600001)(2906002)(5660300002)(38100700002)(36756003)(107886003)(8936002)(26005)(16526019)(6512007)(38350700002)(86362001)(1076003)(6506007)(66556008)(66476007)(66946007)(316002)(8676002)(52116002)(4326008)(83380400001)(69590400013); DIR:OUT; SFP:1102; X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-Network-Message-Id: 931ff29c-9b34-44c0-94c1-08d92c081b38 X-MS-Exchange-CrossTenant-AuthSource: AM7PR08MB5494.eurprd08.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Jun 2021 12:05:57.8983 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: F7UWZIGFloEkz1Ag1GFUsAxJ9rbf1onxMoiZEnYP33+v8AKREoP6qBcj+9n8CJXk/WkJG0WqBwHOCndcCcZyvWc7KkzEcegXJ//sQ3RCC4A= X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR08MB4277 Received-SPF: pass client-ip=40.107.8.90; envelope-from=vsementsov@virtuozzo.com; helo=EUR04-VI1-obe.outbound.protection.outlook.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MSGID_FROM_MTA_HEADER=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" The logic around finding overlay here is not obvious. Actually it does two simple things: 1. If new bs is already in backing chain, split from parent bs by several implicit filters we are done, do nothing. 2. Otherwise, don't try to replace implicit filter. Let's rewrite this in more obvious way. Signed-off-by: Vladimir Sementsov-Ogievskiy --- block.c | 53 ++++++++++++++++------------------------------------- 1 file changed, 16 insertions(+), 37 deletions(-) diff --git a/block.c b/block.c index d86e26299e..1717e5cb98 100644 --- a/block.c +++ b/block.c @@ -4237,7 +4237,7 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, Error **errp) { BlockDriverState *bs = reopen_state->bs; - BlockDriverState *overlay_bs, *below_bs, *new_backing_bs; + BlockDriverState *new_backing_bs; QObject *value; const char *str; @@ -4266,6 +4266,18 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, g_assert_not_reached(); } + if (bs->backing) { + if (bdrv_skip_implicit_filters(bs->backing->bs) == new_backing_bs) { + return 0; + } + + if (bs->backing->bs->implicit) { + error_setg(errp, "Cannot change backing link if '%s' has " + "an implicit backing file", bs->node_name); + return -EPERM; + } + } + /* * Ensure that @bs can really handle backing files, because we are * about to give it one (or swap the existing one) @@ -4283,42 +4295,9 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, return -EINVAL; } - /* - * Find the "actual" backing file by skipping all links that point - * to an implicit node, if any (e.g. a commit filter node). - * We cannot use any of the bdrv_skip_*() functions here because - * those return the first explicit node, while we are looking for - * its overlay here. - */ - overlay_bs = bs; - for (below_bs = bdrv_filter_or_cow_bs(overlay_bs); - below_bs && below_bs->implicit; - below_bs = bdrv_filter_or_cow_bs(overlay_bs)) - { - overlay_bs = below_bs; - } - - /* If we want to replace the backing file we need some extra checks */ - if (new_backing_bs != bdrv_filter_or_cow_bs(overlay_bs)) { - int ret; - - /* Check for implicit nodes between bs and its backing file */ - if (bs != overlay_bs) { - error_setg(errp, "Cannot change backing link if '%s' has " - "an implicit backing file", bs->node_name); - return -EPERM; - } - - reopen_state->replace_backing_bs = true; - reopen_state->old_backing_bs = bs->backing ? bs->backing->bs : NULL; - ret = bdrv_set_backing_noperm(bs, new_backing_bs, set_backings_tran, - errp); - if (ret < 0) { - return ret; - } - } - - return 0; + reopen_state->replace_backing_bs = true; + reopen_state->old_backing_bs = bs->backing ? bs->backing->bs : NULL; + return bdrv_set_backing_noperm(bs, new_backing_bs, set_backings_tran, errp); } /*