From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:24812 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754618AbaG3Hkg (ORCPT ); Wed, 30 Jul 2014 03:40:36 -0400 Message-ID: <53D8A1DA.2060703@cn.fujitsu.com> Date: Wed, 30 Jul 2014 15:42:18 +0800 From: Miao Xie Reply-To: MIME-Version: 1.0 To: Anand Jain , Subject: Re: [PATCH] btrfs: replace seed device followed by unmount causes kernel WARNING In-Reply-To: <1406291614-29544-1-git-send-email-anand.jain@oracle.com> Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: References: <1406291614-29544-1-git-send-email-anand.jain@oracle.com> On Fri, 25 Jul 2014 20:33:34 +0800, Anand Jain wrote: > After the seed device has been replaced the new target device > is no more a seed device. So we need to bring that state in > the fs_devices. > > reproducer: > mount /dev/sdb /btrfs > btrfs dev add /dev/sdc /btrfs > btrfs rep start -B /dev/sdb /dev/sdd /btrfs > umount /btrfs > > WARNING: CPU: 0 PID: 12661 at fs/btrfs/volumes.c:891 __btrfs_close_devices+0x1b0/0x200 [btrfs]() > :: > > __btrfs_close_devices() > :: > WARN_ON(fs_devices->open_devices); > WARN_ON(fs_devices->rw_devices); > > per the btrfs-devlist tool (to dump fs_devices and > btrfs_device from the kernel) the num_device, open_devices, > rw_devices are still at 1 but the total_device is at 2, > even after the seed device has been replaced in the above example. > > Signed-off-by: Anand Jain > --- > fs/btrfs/dev-replace.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c > index eea26e1..a144bb1 100644 > --- a/fs/btrfs/dev-replace.c > +++ b/fs/btrfs/dev-replace.c > @@ -569,6 +569,19 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info, > > btrfs_rm_dev_replace_blocked(fs_info); > > + /* > + * if we are replacing a seed device with a writable device > + * then FS won't be a seeding FS any more. > + */ > + if (src_device->fs_devices->seeding && !src_device->writeable) { First, why not move this code into btrfs_rm_dev_replace_srcdev()? Then if the first condition is true, the second one(!src_device->writeable) must be true because all the devices in the seed fs_device must be read-only. so only the first check is enough. > + fs_info->fs_devices->rw_devices++; If src is missing dev, we would increase it twice. > + fs_info->fs_devices->num_devices++; > + fs_info->fs_devices->open_devices++; > + > + fs_info->fs_devices->seeding = 0; > + fs_info->fs_devices->seed = NULL; In fact, we may have several seed fs_devices in one fs, and the seed fs_device which includes src might not the first one, so assign seed to be NULL would break the seed fs_device list. Thanks Miao > + } > + > btrfs_rm_dev_replace_srcdev(fs_info, src_device); > > btrfs_rm_dev_replace_unblocked(fs_info); >