code: func getProjectID(targetPath string) (uint32, error) {
  	dir, err := openDir(targetPath)
  	if err != nil {
  		return 0, err
  	}
  	defer closeDir(dir)
  
  	var fsx C.struct_fsxattr
  	_, _, errno := unix.Syscall(unix.SYS_IOCTL, getDirFd(dir), C.FS_IOC_FSGETXATTR,
  		uintptr(unsafe.Pointer(&fsx)))
  	if errno != 0 {
  		return 0, errors.Wrapf(errno, "failed to get projid for %s", targetPath)
  	}
  
  	return uint32(fsx.fsx_projid), nil
  }
docs: // getProjectID - get the project id of path on xfs