fix compilation

weed/storage/disk_location.go

@@ -177,6 +177,7 @@ func (l *DiskLocation) loadExistingVolume(dirEntry os.DirEntry, needleMapKind Ne
 	}
 
 	l.SetVolume(vid, v)
+	stats.VolumeServerVolumeCounter.WithLabelValues(v.Collection, "volume", v.DiskType().ReadableString()).Inc()
 
 	size, _, _ := v.FileStat()
 	glog.V(0).Infof("data file %s, replication=%s v=%d size=%d ttl=%s",