code: func (c *nfsdCollector) updateNFSdFileHandlesStats(ch chan<- prometheus.Metric, s *nfs.FileHandles) {
  	ch <- prometheus.MustNewConstMetric(
  		prometheus.NewDesc(
  			prometheus.BuildFQName(namespace, nfsdSubsystem, "file_handles_stale_total"),
  			"Total number of NFSd stale file handles",
  			nil,
  			nil,
  		),
  		prometheus.CounterValue,
  		float64(s.Stale))
  	// NOTE: Other FileHandles entries are unused in the kernel.
  }
docs: // updateNFSdFileHandlesStats collects statistics for the file handles.