Move to be a package level function

fs/fs.go

@@ -470,6 +470,14 @@ func (self *RealFsInfo) GetDirDiskUsage(dir string, timeout time.Duration) (uint
 }
 
 func (self *RealFsInfo) GetDirInodeUsage(dir string, timeout time.Duration) (uint64, error) {
+	return GetDirInodeUsage(dir, timeout)
+}
+
+// GetDirInodeUsage determines the inodes used by a given directory. It avoid
+// traversing onto other devices.
+// If the directory does not exist or it is unable to access a file for some
+// reason, it will return an error.
+func GetDirInodeUsage(dir string, timeout time.Duration) (uint64, error) {
 	if dir == "" {
 		return 0, fmt.Errorf("invalid directory")
 	}
@@ -487,9 +495,6 @@ func (self *RealFsInfo) GetDirInodeUsage(dir string, timeout time.Duration) (uin
 	inodes := map[uint64]struct{}{}
 
 	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
-		if info.Mode() & os.ModeDevice {
-			return nil
-		}
 		if err != nil {
 			return fmt.Errorf("unable to count inodes for part of dir %s: %s", dir, err)
 		}