[arch-general] BTRFS, Rollback, Grub2

[1126]

Hello List!

I can't seem to get rollback-support from mkinitcpio-btrfs to work
properly. I've installed ArchLinux more or less like it is shown in the
wiki-article btrfs-on-root: 
https://wiki.archlinux.org/index.php/Installing_on_Btrfs_root

I changed it some, because I wanted to install ArchLinux on an
encrypted btrfs-root. 

But my root-partition contains a __snapshot folder and an __active
subvolume, but no subvolumes for __home and __usr and such, because I
want to be able to make complete snapshots of my system. 

But when I want to create a snapshot, it asks me where I want to do it,
but I can't give __snapshot as target-folder, because it don't exists in
my system... ;)

So: how should my btrfs-root be mounted in order to be able to make full
use of the rollback-feature provided by mkinitcpio-btrfs?

Thanks in advance for your help,

Christian.