how should i react to 7.e5 in the grunfeld?

1. d4 Pf6 2. c4 g6 3. Pc3 d5 4.cxd5 Pxd5 5. e4 Pxc3 6. bxc3 Lg7

7. e5 

what should i play now? i can't find any game played by masters with this line, but it has been played frequently against me in my games, the opponent will play 8.f4 if i play 7...c5.

please help me

at move 4 how can your big pawn take on d5?

This is german/dutch mark (or maybe both are the same I don't know) for the moves, so P=knight, L=bishop.

I think you should castle, play c5 Nc6 etc. The move e5 brings the pawn closer to your territory, so it is easier to attack it.

very helpful comment. 

the fact that you dug this thread out from the dead to contribute your thoughtful comments speaks volumes.

in grunefield mato had shown some awesome line ie. b4 played against botvinik . interesting.