Comment 9 for bug 1383948

It looks like someone at least attempted to add better btrfs suport
http://lists.gnu.org/archive/html/bug-parted/2013-09/msg00018.html

...
+/* Located 64k inside the partition (start of the first btrfs superblock) */
+#define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
+#define BTRFS_CSUM_SIZE 32
+#define BTRFS_FSID_SIZE 16
...