This tries to be(come) a solution for at least the problems I and II described here. Ideally the other problems described there, can also be dealt with.

This is still a work in progress!

This is still a work in progress!

This is still a work in progress!

This is still a work in progress!

This is still a work in progress!

This is still a work in progress!

This is still a work in progress!

Situtation

What we want

I guess we ultimately want the following:

and in a further step (problem IV) make them all cleanly "unavailable" (on halt/reboot/kexec/etc.).

Making something "available" means, to mount (filesystem) or create/open (block device) it in a clean way, as well as all necessary steps for this, i.e. all other steps of making things available, where the actual target sits on top of (e.g. opening LVM/dm-crypt/loop devices etc. below a filesystem to be mounted).

Secondary goals are: