----- On May 26, 2021, at 4:08 PM, Remi Gauvin remi@georgianit.com wrote:

On 2021-05-26 9:05 a.m., Lentes, Bernd wrote:

Step 1: List the subvolumes that are directly in your @, those will have
to be moved or snapshoted back into the new root.

# btrfs sub list -o /


Hopefully, /@/var/lib/docker/btrfs is the only one, and you can just
move that whole subvolume

# mv /mnt/sub/root-volume/@  /mnt/sub/root-volume/@bad

# btrfs sub snap
/mnt/sub/root-volume/@apt-snapshot-release-upgrade-bionic-2021-05-21_10:38:10
/mnt/sub/root-volume/@

I'm assuming that docker itself has subvolumes, (you truncated the
subvolume list.)  If it does not, you can just snapshot it into the new
@.  If it does have subvolumes, you have to move the whole thing.  Only
do this to a directory/subvolume found with the sub list -o command.

It has:

root@pc65472:/mnt/sub/root-volume/@apt-snapshot-release-upgrade-bionic-2021-05-21_10:38:10# btrfs sub list -o /
ID 724 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/861e224ff669e010d4f88459fcef35a53a13f06a0bae9738c5109442e25d22ef
ID 725 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/e29c8a1388d14e5c609ec699ee646bc435d41f1c856c6622c402941d9a462001-init
ID 726 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/e29c8a1388d14e5c609ec699ee646bc435d41f1c856c6622c402941d9a462001
ID 727 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/0d604657c3d1de047d0e25592701d580c5e25ba80efc7957317d50448e3292fe
ID 728 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/14eb3fffe7da6aff12182b49b28bc4632fdf21a8045f532b5819375f8405f5b2
ID 729 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/b3620e2dad03b2db17c01e27eb005e054948c2deec480c70a6a399802f06cea9
ID 730 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/0e76b1fe113e0801762bb19f444fa911431c309c7f07796866b152be93d7c231
ID 731 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/d06aa183056d47960c53beffd7f1e4765bdda7457b9d80eb5253ae24a41fed11
ID 732 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/2cc3bd6cc3ba6f7b6d59f24d0a1341094dbe85f6378ca77e989efc0072db574f
ID 733 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/5caa7d6a8b6ed674c90eaaa381f9c5f14a16921d5a06a35c3d83ebf330a8e68f
ID 734 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/2f953e73e108714c7f9f3b3b95358ef4352fc29df4372cf7dfec91267bc70954
ID 735 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/df83a5c69bee2d0b06695bf2645b79b93611beeb8aa1a157dfb5ac4253a30928
ID 736 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/e6197fb42e2a624e23a41c0e7cd86d5b5c65b420dfd3d6e1a373c716e79d4311
ID 737 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/ededd3b8d9c0b39f2f2dba0102eec282e134a7cef1d3218e3a0c4266f271396e
ID 738 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/56d73f1207841c59cefc190f380eb62516983e25e0e9806b8166c790d999592c
ID 739 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/f0f3f683697dce3ae18304be732d9cfc3f0aa663d90dca7d351505c15989d9e6
ID 740 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/a9f458390614c253b7d06bbf82da48387220ce455693286bb92ea8373d8c2df3
ID 741 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/9042f96c1bd673d3ba0ca54b9ed82111fbd979338bc94201e5a78aedf4e3e46b
ID 742 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/5e88b78a7a177a1bc902fb0e864d6214777b536c509602552845f3a6e5c70442
ID 743 gen 44757961 top level 257 path @/var/lib/docker/btrfs/subvolumes/3b58a0c99f6345599c3a8295e49cbed58b5c48e5e9c55a0580c1c290db38e7a5
ID 744 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/2609ce598882f98706cdfecdcec4111d7efc41bb7499190f75f62409b3854ad2
ID 745 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/50f1708e7da7690edb8925e9b35417d052681a22c71b45f4ab11a215e9ddae7e
ID 746 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/eb58f0f899885e4b30a2396ab7af6cb0e64a3c28120cd7d08a19bbbc7d6fc244
ID 747 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/a12aa99c06a1851d27811df8494c1e8d45f84148a2089296789ae6621b0cfa0f
ID 748 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/e1509bdf7aa715f881a651cf3e052081641513c8be4eaad9a9fb30430228ca2d
ID 749 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/596b5dce434692b4c2b9c571fcb23c47514ef43bfeb4c8bbde8a0c50fc19aadf
ID 750 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/4e92db3bb0240df49da798dc8297d644ddb7d608e10a0f4ee7bae7320a36e5d8
ID 751 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/169072a0c2c1b4daa16f9cd4be60c7e63dfc2a5fb4198d0ea71f3a25c91bab8e
ID 752 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/f98753db60820b0f45201fb1d76544ccce19cddd5a6acc62e4acdef5a8b60ba2
ID 753 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/145e9aa53bf55045ad73b4d230883be59da59471101f94eada05c0c21db81e6c
ID 754 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/d349cc5329b14b3cc6550ed43c94ae2445c441c6463cb090fb533860102da0fd
ID 755 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/ef7367319f3cea933a873cc94d9a6db0e4108fe5b72ea361e6b42097baff6664
ID 756 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/31bcf7fce390941ab6c335ebcc117b40a011c28849ee63c5d1eb9487b2e83120
ID 757 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/94bcd2a480c89bd2226af9a3b7dd1a645fe5c1ba5a363d6a9542de63fea3d2fc
ID 758 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/cb31c7297ff761a298ecbcefe0ab47314d479b3200ab6af30a4c1b77503e9d37
ID 759 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/f73cb52db8e0bc5a3356a5284d7f733b9b7ba2f6494617fdb0a3004691d080b2
ID 760 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/65416a53d7da4949897c45d390802d24f2fae704d9a64176fd05d8241ed3aacd
ID 761 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/183e345921700ffea88943d1d1fdc8958038245f145cb78dbf0b292059546c3e
ID 762 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/22ffacbd4e0c0778d1610da9637f2b6058375fff58f07035a431258f0aec49ab
ID 763 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/d4eccdcd6659628ea02834929f6187e0c60fdbcb950a2b498973c4a806ed90f3
ID 764 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/b85f5e75207d899700515ebada8dcec8dd8f38f268da9bb382835f3101243d95
ID 765 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/5f66e708001a623ae8f219fcbf5a9a9b020bc12403c2cb9ad788880caa79b912-init
ID 766 gen 44757962 top level 257 path @/var/lib/docker/btrfs/subvolumes/5f66e708001a623ae8f219fcbf5a9a9b020bc12403c2cb9ad788880caa79b912

mv /mnt/sub/root-volume/@bad/var/lib/docker/btrfs
/mnt/sub/root-volume/@/var/lib/docker/btrfs

You need to repeat this for any other subvolumes found in the first sub
list command.

OK. What is their purpose ?

Reboot

OK. Thanks, i will try that and keep you informed.

Bernd