How to restore grub in Ubuntu on btrfs?

Question

linux

I start LiveUSB, open the console
Then, through fdsik -l, I look at the partitions
/ dev / sda1 - the partition with the btrfs system
/ dev / sda2 - extended partition
/ dev / sda3 - home partition on ext4
I mount / mnt partition / dev / sda1
Then I see in / mnt the following folders @ and boot and some other boot_rm
I mount further
mount --bind /dev /mnt/@/dev
mount --bind /sys /mnt/@/sys
mount --bind /proc /mnt/@ /proc
mount --bind /boot /mnt/@/boot
and go to chroot /mnt/@
When I try to install grub-install /dev/sda it says /cow path not found ... But even if I
mount - -bind /boot /mnt/boot then the same problem still occurs....
And yes, my boot is not taken out of the system at the moment ...

Answer 1

Read this: https://help.ubuntu.com/community/btrfs
The default configuration is to create a subvolume @ for the root.
That is, you need to mount not just /dev/sda1, but a subvolume, for example, like this:
Here is another article on installing GRUB: https://help.ubuntu.com/community/Grub2/Installing
There is an example for BTRFS:
That is, you can either do this:

sudo mount -o subvol=/@ /dev/sda1 /mnt
sudo grub-install --boot-directory=/mnt/boot /dev/sda

either like this:

sudo mount /dev/sda1 /mnt
sudo grub-install --boot-directory=/mnt/@/boot /dev/sda