perl release holds

#!/usr/bin/env perl
use Modern::Perl;

foreach my $fs (@ARGV) {
    my ($refcount, @refs, %holds);
    # get a hash of all subsidiary datasets with references
    say "Looking up userrefs for $fs...";
    @refs = qx(zfs get -H -r userrefs $fs)
        or die "$~\n$^E\n";
    foreach my $line (@refs) {
        next unless $line =~ m/
        (\S+)
        \s+
        userrefs
        \s+
        (\d+)
        /igx;
        unless ($2) {
            say "clean: $1";
            next;
        }
        else {
            say "dirty: $1";
            $holds{$1} = $2;
        }
    }
    say "DONE\n";

    say "Releasing holds...";
    foreach my $dataset (keys %holds) {
        # prune holds recursively
        my @tags = qx(zfs holds -H -r $dataset)
            or die "$!\n$^E\n";
        foreach my $line (@tags) {
            next unless $line =~ m/
            (\S+)   # dataset - could be different for a subsidiary
            \s+
            (\.send-\S+)   # only prune tags left by `zfs send`
            /igx;
            my ($snapshot, $tag) = ($1, $2);

            print "Releasing $snapshot from $tag...";
            qx(zfs release -r $tag $snapshot);
                or die "$!\n$^E\n";
            say "ok"
        }
    }
    say "DONE\n";
}
exit 0;