On 2020/6/17 上午3:25, Josef Bacik wrote:
> On 6/15/20 10:17 PM, Qu Wenruo wrote:
>> btrfs_root::anon_dev is an indicator for different subvolume namespaces.
>> Thus it should always be initialized to an anonymous block device.
>>
>> Add a safe net to catch such uninitialized values.
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
> 
> Can we handle stat->dev not having a device set?  Or will this blow up
> in other ways?  Thanks,

We can handle it without any problem, just users get confused.

As a common practice, we use different bdev as a namespace for different
subvolumes.
Without a valid bdev, some user space tools may not be able to
distinguish inodes in different subvolumes.

Thanks,
Qu
> 
> Josef