Some Ext4 Filesystems Cannot Be Converted to Btrfs

Not all ext4 filesystems can be converted to a btrfs filesystem using the btrfs-convert utility. Btrfs has some limitations. The mkfs.btrfs utility will complain if you try to create a fileystem that is less than 256Mb. Btrfs-convert used fail when a file had more than 244 hard links associated with it but that limitation is long gone. I hit another limitation recently when I tried to convert a 477Mb ext4 filesystem to btrfs. Btrfs-convert failed with a message of: block size is too small For some reason this Oracle document states that you cannot convert an ext4 /boot filesytem to