code: func (c *nfsdCollector) updateNFSdInputOutputStats(ch chan<- prometheus.Metric, s *nfs.InputOutput) {
  	ch <- prometheus.MustNewConstMetric(
  		prometheus.NewDesc(
  			prometheus.BuildFQName(namespace, nfsdSubsystem, "disk_bytes_read_total"),
  			"Total NFSd bytes read.",
  			nil,
  			nil,
  		),
  		prometheus.CounterValue,
  		float64(s.Read))
  	ch <- prometheus.MustNewConstMetric(
  		prometheus.NewDesc(
  			prometheus.BuildFQName(namespace, nfsdSubsystem, "disk_bytes_written_total"),
  			"Total NFSd bytes written.",
  			nil,
  			nil,
  		),
  		prometheus.CounterValue,
  		float64(s.Write))
  }
docs: // updateNFSdInputOutputStats collects statistics for the bytes in/out.