You can use the btrfs-convert utility to convert an ext2, ext3, or ext4 file system to btrfs. The utility preserves an image of the original file system in a snapshot named ext2_saved. This snapshot allows you to roll back the conversion, even if you have made changes to the btrfs file system.

If you convert the root file system to btrfs, you can use snapshots to roll back changes such as upgrades that you have made to the file system.