Another bullet list of how to get btrfs with encryption on your system.

1. fdisk /dev/sda ( create one boot partition 100mb, create one root partition and one swap [ I dont use swap, so you dont have to create a swap partition ]
2. mkfs.ext4 /dev/sda1
3. cryptsetup -y -s 512 -c aes-xts-plain luksFormat /dev/sda2
4. cryptsetup luksOpen /dev/sda2 slackcrypt
5. mkfs.btrfs /dev/mapper/slackcrypt
6. mount /dev/mapper/slackcrypt /mnt ; cd /mnt
7. btrfs subvolume create system ; btrfs subvolume create home ; btrfs subvolume create var ; btrfs subvolume create usr
8. confirm you’ve created the subvolumes : btfs subvolume list /mnt
9. cd / ; umount /mnt
10. mount -t btrfs -o subvol=system /mnt (mounting the main subvolume)
11. mkdir -p /mnt/{home,usr,var,boot}
12. mount -t btrfs -o subvol=home /mnt/home ; mount -t btrfs -o subvol=usr /mnt/usr; mount -t btrfs -o subvol=var /mnt/var
13. mount /dev/sda1 /mnt/boot
12. run setup & DO NOT FORMAT and do not exit once finish installing
13. chroot /mnt
14. use /usr/share/mkinitrd/ or run your own mkinitrd command.
15. update grub or lilo and point to the initrd file

—I forgot the rest of the steps I took, I’ll redo the process on a virtual box or something but this should 99.9999 % to being finished.