open my $fh, '<', $filename or die "Can't open $filename: $!\n";
_restore_offset($filename, $fh);
while (my $line = <$fh>) {
  # do stuff here
}
_record_offset($filename, $fh);
close $fh;

sub _restore_offset {
  my ($filename, $fh) = @_;
  # Get $offset and $last_inode from database
  my $current_inode = (stat $fh)[1];
  return unless $current_inode == $last_inode;
  
  seek $fh, $offset, 0;
} 

sub _record_offset {
  my ($filename, $fh) = @_;

  my $offset = tell $fh;
  my $inode = (stat $fh)[1];
  # Stuff $offset and $inode back into database
}