df: cleanup and refactor

src/uu/df/src/df.rs

@@ -292,9 +292,9 @@ fn filter_mount_list(vmi: Vec<MountInfo>, opt: &Options) -> Vec<MountInfo> {
 /// Assign 1 `MountInfo` entry to each path
 /// `lofs` entries are skipped and dummy mount points are skipped
 /// Only the longest matching prefix for that path is considered
+/// `lofs` is for Solaris style loopback filesystem and is present in Solaris and FreeBSD.
+/// It works similar to symlinks
 fn get_point_list(vmi: &[MountInfo], paths: &[String]) -> Vec<MountInfo> {
-    // Choose MountInfo per input_path
-    // Skip lofs, skip dummy and select longest match
     paths
         .iter()
         .map(|p| {

tests/by-util/test_df.rs

@@ -59,6 +59,7 @@ fn test_order_same() {
 }
 
 /// Test of mount point begin repeated
+#[cfg(unix)]
 #[test]
 fn test_output_mp_repeat() {
     let output1 = new_ucmd!().arg("/").arg("/").succeeds().stdout_move_str();