From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:31686 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750855AbaFME0j (ORCPT ); Fri, 13 Jun 2014 00:26:39 -0400 From: Anand Jain To: linux-btrfs@vger.kernel.org Cc: quwenruo@cn.fujitsu.com, wangsl.fnst@cn.fujitsu.com Subject: [PATCH 2/2] btrfs: check generation as replace duplicates devid+uuid Date: Fri, 13 Jun 2014 12:26:21 +0800 Message-Id: <1402633581-19265-2-git-send-email-Anand.Jain@oracle.com> In-Reply-To: <1402633581-19265-1-git-send-email-Anand.Jain@oracle.com> References: <1402633581-19265-1-git-send-email-Anand.Jain@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: From: Anand Jain When FS in unmounted we need to check generation number as well since devid+uuid combination could match with the missing replaced disk when it reappears, and without this patch it might pair with the replaced disk again. device_list_add() function is called in the following threads, mount device option mount argument ioctl BTRFS_IOC_SCAN_DEV (btrfs dev scan) ioctl BTRFS_IOC_DEVICES_READY (btrfs dev ready ) they have been unit tested to work fine with this patch. If the user knows what he is doing and really want to pair with replaced disk (which is not a standard operation), then he should first clear the kernel btrfs device list in the memory by doing the module unload/load and followed with the mount -o device option. Signed-off-by: Anand Jain --- fs/btrfs/volumes.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 56822f0..bb1b4bd 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -523,6 +523,16 @@ static noinline int device_list_add(const char *path, if (fs_devices->opened) return -EBUSY; + else { + /* + * That is if the FS is _not_ mounted and if you are here, that + * means there is more than one disk with same uuid and devid. + * We keep the one with larger generation number or the last-in + * if generation are equal. + */ + if (found_transid < device->generation) + return -EINVAL; + } name = rcu_string_strdup(path, GFP_NOFS); if (!name) @@ -535,6 +545,15 @@ static noinline int device_list_add(const char *path, } } + /* + * Unmount does not free the btrfs_device struct but would zero + * generation along with most of the other members. So just update + * it back. We need it to pick the disk with largest generation + * (as above). + */ + if (!fs_devices->opened) + device->generation = found_transid; + if (found_transid > fs_devices->latest_trans) { fs_devices->latest_devid = devid; fs_devices->latest_trans = found_transid; -- 1.8.5.3