On 17.07.19 г. 13:29 ч., Andrei Borzenkov wrote: > On Wed, Jul 17, 2019 at 1:14 PM Nikolay Borisov <nborisov@xxxxxxxx> 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? >
