How to drop all events which doesn't match the pattern ?

My config file is like this: http://pastebin.com/sKCjGED3

I want to drop all the messages which are not matched with the defined grep pattern.

when I remove drop => false, i see indexer dropping all events, whether matched or not.

What I have to do drop all the events which are not matched with any of the grep pattern?

Where I am doing wrong?

Thnx