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 <anand.j...@oracle.com>
> ---
> 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);
>
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