[FEAT] Subvolumes for virtual machines/containers directories in /var/lib

[silopolis]

Hi,

Thinking it was originating from there, and because it is my current daily driver, I started by creating this request for Kali's package here https://gitlab.com/kalilinux/packages/partman-btrfs/-/issues/1.

As I'm evaluating migrating to Kaisen I'm duplicating it here:

It'd be nice if creation of subvolumes for these special directories could be supported.

/var/lib/qemu/
/var/lib/libvirt/
/var/lib/xen/
/var/lib/docker/
/var/lib/containerd/
/var/lib/containers (Podman & CRI-O)
/var/lib/incus/
/var/lib/vz/
/var/lib/kubelet/

If I'm not mistaken, I could add this to mount.d/btrfs, but I wasn't able to find where and how to also modify partman's subvolume scheme or recipe.