How to move btrfs subvolume to different partition?

English Install/Boot/Login
1

Hello,
my root / partition is full because /var/lib/flatpak/repo/tmp on @/var subvolume.

flatpak uninstall --unused

didn’t help as there is apparently nothing unused to uninstall.

I’ve got plenty of space on /home partition. I could just create symlink to /home/tmp but creating /var subvolume on that partition could be a more elegant solution.

So how can I do it?

some info:

cat /etc/fstab
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /                      btrfs  defaults                        0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /var                   btrfs  subvol=/@/var                   0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /usr/local             btrfs  subvol=/@/usr/local             0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /srv                   btrfs  subvol=/@/srv                   0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /root                  btrfs  subvol=/@/root                  0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /opt                   btrfs  subvol=/@/opt                   0  0
/dev/mapper/cr-auto-2                      /home                  btrfs  defaults                        0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /boot/grub2/arm64-efi  btrfs  subvol=/@/boot/grub2/arm64-efi  0  0
UUID=B626-F98E                             /boot/efi              vfat   utf8                            0  2
UUID=5c745f86-702a-4dea-8275-708712259704  swap                   swap   defaults                        0  0
UUID=cb70b6ce-5697-43bd-a1e0-1ff85723c93e  /.snapshots            btrfs  subvol=/@/.snapshots            0  0

btrfs subvolume list /
ID 256 gen 19 top level 5 path @
ID 257 gen 13666 top level 256 path @/var
ID 258 gen 13437 top level 256 path @/usr/local
ID 259 gen 13595 top level 256 path @/srv
ID 260 gen 13623 top level 256 path @/root
ID 261 gen 13595 top level 256 path @/opt
ID 262 gen 13595 top level 256 path @/boot/grub2/arm64-efi
ID 263 gen 13617 top level 256 path @/.snapshots
ID 301 gen 4986 top level 263 path @/.snapshots/37/snapshot
...

Thank you for help.

2

Are you installing Flatpaks system-wide (vs user-based, which is recommended)?

Have you run “flatpak repair” ??

I’d be tempted to clear out that “tmp” sub-dir, if mine was consuming excessive space.

My “tmp” in that flatpak sub-dir path is meaningless (it’s about 64 bytes):

user@machine :~> du -h -d 2 /var/lib/flatpak
0       /var/lib/flatpak/repo/tmp  <==== almost zero bytes
0       /var/lib/flatpak/repo/extensions
0       /var/lib/flatpak/repo/state
132K    /var/lib/flatpak/repo/refs
3.3G    /var/lib/flatpak/repo/objects <==== most disk usage
3.3G    /var/lib/flatpak/repo
8.7M    /var/lib/flatpak/appstream/flathub
8.7M    /var/lib/flatpak/appstream
[ ... ]
user@machine :~>