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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 9273CC433EF for ; Mon, 6 Sep 2021 14:37:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7648B60232 for ; Mon, 6 Sep 2021 14:37:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243574AbhIFOjD (ORCPT ); Mon, 6 Sep 2021 10:39:03 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:15297 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243274AbhIFOi4 (ORCPT ); Mon, 6 Sep 2021 10:38:56 -0400 Received: from dggeme754-chm.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4H39wK5dZbz8snj; Mon, 6 Sep 2021 22:37:21 +0800 (CST) Received: from huawei.com (10.175.127.227) by dggeme754-chm.china.huawei.com (10.3.19.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Mon, 6 Sep 2021 22:37:49 +0800 From: Ye Bin To: , , CC: , , Ye Bin Subject: [PATCH -next 0/6] Fix some issues about mmp Date: Mon, 6 Sep 2021 22:47:48 +0800 Message-ID: <20210906144754.2601607-1-yebin10@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggeme754-chm.china.huawei.com (10.3.19.100) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I test mmp function as follow steps: 1. Inject delay 5s in ext4_multi_mount_protect function after "skip:" label. 2. Share HostA block device(sda) with HostB(nbd0) by NBD. 3. Enable mmp feature when mkfs.ext4 sda. 4. Mount sda and nbd0 at the same time. I found kmmpd never trigger detect multi-mount. Reason is as follow: 1. Kmmpd init seq with 0, if two host have same nodename, will lead to detect confliction very slow, even never detect confliction. 2. When detect confliction in kmmpd, we get 'check_bh' is same with 'bh'. so we compare data with itself. 3. We only trigger detect when ”diff > mmp_check_interval * HZ“, 'mmp_check_interval' is double of 'mmp_update_interval', 'diff' is about 'mmp_update_interval'. So 'diff' is little than 'mmp_check_interval * HZ' normaly. And i also found that 'check_interval' value store in disk is not sure after umount. Ye Bin (6): ext4: init seq with random value in kmmpd ext4: introduce last_check_time record previous check time ext4: compare to local seq and nodename when check conflict ext4: avoid to re-read mmp check data get from page cache ext4: avoid to double free s_mmp_bh ext4: fix possible store wrong check interval value in disk when umount fs/ext4/mmp.c | 77 ++++++++++++++++++++++++++++----------------------- 1 file changed, 43 insertions(+), 34 deletions(-) -- 2.31.1