init.el

(define-ibuffer-filter filename-or-dired
  "Toggle current view to buffers with filename or dired-directory matching QUALIFIER."
  (:description "filename-or-dired"
   :reader (read-from-minibuffer "Filter by filename (regexp): "))
  (or
   (ibuffer-awhen (buffer-local-value 'buffer-file-name buf)
     (string-match qualifier it))
   (ibuffer-awhen (buffer-local-value 'dired-directory buf)
     (string-match qualifier it))))