Playing approximately 2/1 with a very good partner. No forcing 1N response.
2N response would have been either a limit raise or a gf raise with four trumps
2♠ rebid does not promise six although six is likely over 2♣
4♠ over 2♠ would have been "picture": good spades and good clubs.
4♣ is a serious slam try.
Benefits include:
Plus... it's free!