It seems that btrfs/ioctl.h is not there in 3.13.1, so btrfs driver fails to build. Possibly, the correct file now is include/uapi/linux/btrfs.h, though I failed to build the code with it as well:

/usr/include/btrfs/ioctl.h:74:39: error: expected ':', ',', ';', '}' or '__attribute__' before '*' token
   struct btrfs_qgroup_inherit __user *qgroup_inherit;