Now, df always displays the device file name corresponding to the

Now, df always displays the device file name corresponding to the
listed mount point under `Filesystem'.  Before, for an unmounted
block- or character-special file argument, it would display the
command-line argument instead.

(show_disk): Return a value indicating whether
there was a match.  Don't try to find a mount point here.
(show_entry): If show_disk doesn't find a match, call show_point.