(To clarify: this is about fixing grub by using a LiveCD to rebuild grub, a pretty standard operation e.g. https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows, with the difficulty being btrfs in use)
Ubuntu partition is /dev/sda5 and is btrfs, with encrypted home.
mount /dev/sda5 /mnt cd /mnt ls
I get two directories: @ and @home and the / file system is under @
fails with 'failed to run command /bin/bash'
looks like it works, since it lets me mount the /proc /dev etc via
for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt$i"; done
update-grub fails with
grub-probe: cannot find a device for / (is /dev mounted?).
fstab looks like this:
UUID=<...> / btrfs defaults,subvol=@ 0 1
swap and home are encrypted.