From patchwork Thu Jul 3 10:22:05 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miao Xie X-Patchwork-Id: 4472281 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 9B53A9F26C for ; Thu, 3 Jul 2014 10:21:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B790D20304 for ; Thu, 3 Jul 2014 10:21:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7025201D3 for ; Thu, 3 Jul 2014 10:21:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759246AbaGCKVJ (ORCPT ); Thu, 3 Jul 2014 06:21:09 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:43967 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753831AbaGCKUq (ORCPT ); Thu, 3 Jul 2014 06:20:46 -0400 X-IronPort-AV: E=Sophos;i="5.00,825,1396972800"; d="scan'208";a="32789497" Received: from unknown (HELO edo.cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 03 Jul 2014 18:18:01 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id s63AKgtq013542; Thu, 3 Jul 2014 18:20:42 +0800 Received: from miao.fnst.cn.fujitsu.com (10.167.226.169) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.181.6; Thu, 3 Jul 2014 18:20:54 +0800 From: Miao Xie To: CC: Anand Jain , Wang Shilong Subject: [PATCH V4 1/9] Btrfs: device_list_add() should not update list when mounted Date: Thu, 3 Jul 2014 18:22:05 +0800 Message-ID: <1404382933-26672-1-git-send-email-miaox@cn.fujitsu.com> X-Mailer: git-send-email 1.9.3 MIME-Version: 1.0 X-Originating-IP: [10.167.226.169] Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Anand Jain device_list_add() is called when user runs btrfs dev scan, which would add any btrfs device into the btrfs_fs_devices list. Now think of a mounted btrfs. And a new device which contains the a SB from the mounted btrfs devices. In this situation when user runs btrfs dev scan, the current code would just replace existing device with the new device. Which is to note that old device is neither closed nor gracefully removed from the btrfs. The FS is still operational with the old bdev however the device name is the btrfs_device is new which is provided by the btrfs dev scan. reproducer: devmgt[1] detach /dev/sdc replace the missing disk /dev/sdc btrfs rep start -f 1 /dev/sde /btrfs Label: none uuid: 5dc0aaf4-4683-4050-b2d6-5ebe5f5cd120 Total devices 2 FS bytes used 32.00KiB devid 1 size 958.94MiB used 115.88MiB path /dev/sde devid 2 size 958.94MiB used 103.88MiB path /dev/sdd make /dev/sdc to reappear devmgt attach host2 btrfs dev scan btrfs fi show -m Label: none uuid: 5dc0aaf4-4683-4050-b2d6-5ebe5f5cd120^M Total devices 2 FS bytes used 32.00KiB^M devid 1 size 958.94MiB used 115.88MiB path /dev/sdc <- Wrong. devid 2 size 958.94MiB used 103.88MiB path /dev/sdd since /dev/sdc has been replaced with /dev/sde, the /dev/sdc shouldn't be part of the btrfs-fsid when it reappears. If user want it to be part of it then sys admin should be using btrfs device add instead. [1] github.com/anajain/devmgt.git Signed-off-by: Anand Jain Signed-off-by: Wang Shilong Signed-off-by: Miao Xie Reviewed-by: Satoru Takeuchi --- Changelog v3->v4: - Fix the over-80-charactor problem --- fs/btrfs/volumes.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a9c11a0..16e71a1 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -508,6 +508,33 @@ static noinline int device_list_add(const char *path, ret = 1; device->fs_devices = fs_devices; } else if (!device->name || strcmp(device->name->str, path)) { + /* + * When FS is already mounted. + * 1. If you are here and if the device->name is NULL that + * means this device was missing at time of FS mount. + * 2. If you are here and if the device->name is different + * from 'path' that means either + * a. The same device disappeared and reappeared with + * different name. or + * b. The missing-disk-which-was-replaced, has + * reappeared now. + * + * We must allow 1 and 2a above. But 2b would be a spurious + * and unintentional. + * + * Further in case of 1 and 2a above, the disk at 'path' + * would have missed some transaction when it was away and + * in case of 2a the stale bdev has to be updated as well. + * 2b must not be allowed at all time. + */ + + /* + * As of now don't allow update to btrfs_fs_device through + * the btrfs dev scan cli, after FS has been mounted. + */ + if (fs_devices->opened) + return -EBUSY; + name = rcu_string_strdup(path, GFP_NOFS); if (!name) return -ENOMEM;