fastio question

In a filter driver I use a lot of file reading form my IRP_MJ_CREATE
dispatch routine.My problem is that the reads go via fastio and for some
files the sistem hangs when my driver receives IRP_MJ_FLUSH_BUFFERS and I
process a fastio-read call.What should I do?
I try syncronization with KeWaitForSingleObject and events ,but it didnt
works