From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:21067 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756295AbaEPOLk (ORCPT ); Fri, 16 May 2014 10:11:40 -0400 Message-ID: <53761D30.6080207@oracle.com> Date: Fri, 16 May 2014 22:14:08 +0800 From: Anand Jain MIME-Version: 1.0 To: Wang Shilong , linux-btrfs@vger.kernel.org Subject: Re: [PATCH] Btrfs: set right total device count for seeding support References: <1399971906-1237-1-git-send-email-wangsl.fnst@cn.fujitsu.com> <1399971906-1237-2-git-send-email-wangsl.fnst@cn.fujitsu.com> In-Reply-To: <1399971906-1237-2-git-send-email-wangsl.fnst@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Wang, There seems to be a problem - after we delete the seed disk, the total_devices didn't decrement back to 1. reproducer as in the below test case. (I used btrfs-devlist (posted) to check fs_devices). > # mkfs.btrfs -f /dev/sdb > # btrfstune -S 1 /dev/sdb > # mount /dev/sdb /mnt > # btrfs device add -f /dev/sdc /mnt --->fs_devices->total_devices = 1 mount -o rw,remount /mnt btrfs dev del /dev/sdb /mnt --> fs_devices->total_devices is still 2 Thanks, Anand On 13/05/14 17:05, Wang Shilong wrote: > Seeding device support allows us to create a new filesystem > based on existed filesystem. > > However newly created filesystem's @total_devices should include seed > devices. This patch fix the following problem: > > # mkfs.btrfs -f /dev/sdb > # btrfstune -S 1 /dev/sdb > # mount /dev/sdb /mnt > # btrfs device add -f /dev/sdc /mnt --->fs_devices->total_devices = 1 > # umount /mnt > # mount /dev/sdc /mnt --->fs_devices->total_devices = 2 > > This is because we record right @total_devices in superblock, but > @fs_devices->total_devices is reset to be 0 in btrfs_prepare_sprout(). > > Fix this problem by not resetting @fs_devices->total_devices. > > Signed-off-by: Wang Shilong > --- > fs/btrfs/volumes.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 6fd7fe6..19b2d32 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -1883,7 +1883,6 @@ static int btrfs_prepare_sprout(struct btrfs_root *root) > fs_devices->seeding = 0; > fs_devices->num_devices = 0; > fs_devices->open_devices = 0; > - fs_devices->total_devices = 0; > fs_devices->seed = seed_devices; > > generate_random_uuid(fs_devices->fsid); >