Odd, this first line  opendir my $dirh, $path || return FAILED;
should be opendir (my $dirh, $path) || return FAILED; or opendir my $dirh, $path or return FAILED; for it to work right. The || has a higher precedence than "or", so the parens are needed if that operator is used.

Update:

I recoded your routine with File::Find to show how to use this critter. I was not sure what this "Directory Size" thing was about? The size of the directory is the sum of the sizes of the files.

I did use the special _ (underscore, not $_) variable. When Perl does a file test, it does a stat() and if you use the _ variable for another file test, it uses the cached results from stat() from the previous file test. This speeds things up considerably if you are doing a lot of file tests. $File::Find::name is the name of the current file, $File::Find::dir is the name of the current directory.

I did not put an explicit stat() call in the wanted subroutine. I've seen this in older code. There was a reason for this as some obscure thing could happen that could cause stat() to fail. I did some searching around for that reason but wasn't able to find it. Maybe some other Monk knows? Anyway, I don't think that is necessary anymore - so I didn't do it. Also, I think if the stat fails, the file test fails, so the way the code below is written, this would have the effect of ignoring that file.

This Dir::Walk thing looks pretty worthless to me.
Anyway this code runs on my machine... have fun!

#!/usr/bin/perl
use strict;
use warnings;

use File::Find;

my $fileN = 0;          # Counter for number of files
my $fileSize = 0;       # Total size of files
my $backupN = 0;        # Counter for number of backup files
my $backupSize = 0;     # Total size of backup files
my $txtN = 0;           # Counter for number of text files
my $txtSize = 0;        # Total size of text files
my $plN = 0;            # Counter for number of PERL scripts
my $plSize = 0;         # Total size of PERL scripts
my $dirN = 0;           # Counter for number of directories
my $dirSize = 0;        # Total size of directories ??? what ???

find (\&wanted, ('C:/temp'));  #note: find takes a list of directories
printStats();

sub wanted
{
    if (-d)
    {
        $dirN++;
        return;
    }
    
    if (-f _)
    {
        $fileN++;
        $fileSize += -s _;

        if ($File::Find::name =~ m/~$/) #backup
        {
           $backupN++; 
           $backupSize += -s _;
        }
        elsif ($File::Find::name =~ m/\.txt$/)
        {
           $txtN++;
           $txtSize += -s _;
        }
        elsif($File::Find::name =~ m/\.pl$/)
        {
           $plN++;
           $plSize += -s _;
        } 
    }
}


#####
# p r i n t S t a t s
# Print out all counters at the end of the walk
#####
sub printStats {
    printf "%-12.12s %-15d %-20d\n", "Files", $fileN, $fileSize;
    printf "    %-8.8s %-15d %-20d\n", "Backup", $backupN, $backupSize
+;
    printf "    %-8.8s %-15d %-20d\n", "Text", $txtN, $txtSize;
    printf "    %-8.8s %-15d %-20d\n", "PERL", $plN, $plSize;
    print "\n";
    printf "%-12.12s %-15d\n", "Directories", $dirN;
}

__END__
.....prints on my machine:.....
Files        2620            671260264           
    Backup   0               0                   
    Text     155             15244026            
    PERL     974             6015816             

Directories  46
[download]