On 17.07.19 г. 13:29 ч., Andrei Borzenkov wrote:
> On Wed, Jul 17, 2019 at 1:14 PM Nikolay Borisov <[email protected]> wrote:
>>
>>
>>
>> On 17.07.19 г. 12:11 ч., Ulli Horlacher wrote:
>>> On Wed 2019-07-17 (11:24), Nikolay Borisov wrote:
>>>>
>>>>
>>>> On 17.07.19 3. 2:24 G., Ulli Horlacher wrote:
>>>>
>>>>> I thought, I can recognize a snapshot when it has a Parent UUID, but this
>>>>> is not true for snapshots of toplevel subvolumes:
>>>>
>>>> As you have asked this before - in my testing this is not true.
>>>
>>> It is true on all my SUSE and Ubuntu systems, for all versions.
>>
>> That's strange, as I've shown in the previous thread, using the latest
>> master doesn't exhibit this behavior.
>
> I doubt you are not aware that distributions rarely use latest master.
>
> Actually I have here openSUSE Tumbleweed; root top level subvolume
> does not have UUID but if I create new filesystem *now* it does. btrfs
> tools have been updated since initial installation.
I have an ubuntu 18.04 installation lying around and I see :
sudo btrfs subvolume show btrfs-mount/
/
Name: <FS_TREE>
UUID: -
Parent UUID: -
Received UUID: -
Creation time: -
Subvolume ID: 5
Generation: 4
Gen at creation: 0
Parent ID: 0
Top level ID: 0
Flags: -
Snapshot(s):
This is really odd... So this indeed seems to be a userspace problem.
However, creating a subvolume and then a snapshot I see sane output - parent
UUID being there and UUID being there for a kernel-created subvol. :
nborisov@fisk:~/projects/kernel/source$ sudo btrfs subvolume show
btrfs-mount/subvol1-snap1/
subvol1-snap1
Name: subvol1-snap1
UUID: 3aebb55e-57bc-9c46-9a34-4ac0220d602e
Parent UUID: fe7e68c6-b9c8-ce4d-8467-7229bd39b0eb
Received UUID: -
Creation time: 2019-07-17 13:55:31 +0300
Subvolume ID: 258
Generation: 9
Gen at creation: 9
Parent ID: 5
Top level ID: 5
Flags: -
Snapshot(s):
nborisov@fisk:~/projects/kernel/source$ sudo btrfs subvolume show
btrfs-mount/subvolume1/
subvolume1
Name: subvolume1
UUID: fe7e68c6-b9c8-ce4d-8467-7229bd39b0eb
Parent UUID: -
Received UUID: -
Creation time: 2019-07-17 13:55:14 +0300
Subvolume ID: 257
Generation: 9
Gen at creation: 8
Parent ID: 5
Top level ID: 5
Flags: -
Snapshot(s):
subvol1-snap1
>
> Better question would be - is it possible to fix it for existing
> filesystems that had been created using old tools?
>
