Emacs org-mode: textual reference to a file:line

(defun position-to-kill-ring ()
  "Copy to the kill ring a string in the format \"file-name:line-number\"
for the current buffer's file name, and the line number at point."
  (interactive)
  (kill-new
   (format "%s:%d" (buffer-file-name) (save-restriction
                                        (widen) (line-number-at-pos)))))

You want to use the org-create-file-search-functions and org-execute-file-search-functions hooks.

For example, if you need the search you describe for text-mode files, use this:

(add-hook 'org-create-file-search-functions
      '(lambda ()
         (when (eq major-mode 'text-mode)
           (number-to-string (line-number-at-pos)))))

(add-hook 'org-execute-file-search-functions
      '(lambda (search-string)
         (when (eq major-mode 'text-mode)
           (goto-line (string-to-number search-string)))))

Then M-x org-store-link RET will do the right thing (store a line number as the search string) and C-c C-o (i.e. M-x org-open-at-point RET) will open the file and go to this line number.

You can of course check for other modes and/or conditions.