switch to ext4

we dont use any btrfs features anymore

btrfs backend for containers seems to have worse performance and worse support

post-debootstrap-installer.sh

@@ -23,7 +23,7 @@ apt-get -y install locales
 
 ### boot
 
-apt-get -y install mdadm cryptsetup systemd systemd-sysv btrfs-progs firmware-linux lvm2
+apt-get -y install mdadm cryptsetup systemd systemd-sysv firmware-linux
 systemctl enable fstrim.timer
 
 # --force-confold because we already provide /etc/dropbear-initramfs/config

setup.sh

@@ -25,12 +25,12 @@ unset root_pwd
 chroot=/mnt/root-unlocked
 
 # root device
-mkfs.btrfs -f /dev/mapper/root-unlocked
+mkfs.ext4 -f /dev/mapper/root-unlocked
 mkdir /mnt/root-unlocked
 mount /dev/mapper/root-unlocked /mnt/root-unlocked
 
 # boot device
-mkfs.btrfs -f "$boot"
+mkfs.ext4 -f "$boot"
 mkdir "$chroot/boot"
 mount "$boot" "$chroot/boot"