From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:56580 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1755959AbaGCKUr (ORCPT ); Thu, 3 Jul 2014 06:20:47 -0400 From: Miao Xie To: CC: Anand Jain , Wang Shilong Subject: [PATCH V2 2/9] btrfs: check generation as replace duplicates devid+uuid Date: Thu, 3 Jul 2014 18:22:06 +0800 Message-ID: <1404382933-26672-2-git-send-email-miaox@cn.fujitsu.com> In-Reply-To: <1404382933-26672-1-git-send-email-miaox@cn.fujitsu.com> References: <1404382933-26672-1-git-send-email-miaox@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain 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 Signed-off-by: Wang Shilong Signed-off-by: Miao Xie --- Changelog v1->v2: - Fix the over-80-charactor problem and unreasonable error number --- fs/btrfs/volumes.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 16e71a1..1891541 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -532,8 +532,19 @@ static noinline int device_list_add(const char *path, * 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) + 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 -EEXIST; + } name = rcu_string_strdup(path, GFP_NOFS); if (!name) @@ -546,6 +557,15 @@ 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; -- 1.9.3