rear version 1.17.2 plus a SLE12-SP1 specific patch to make it work with btrfs default structure on SLE12-SP1 (https://github.com/rear/rear/issues/556). Regardless that it is not yet completely implemented (chattr support is missing) I submitted it right now to have it public available because at least for me the first basic step works that is: recovery of a SLES12-SP1 system with default btrfs structure (but currently without chattr support)