Attached is an updated fsx that we are using to test with. It was originally gotten from Andrew Morton some years ago, and has subsequently had some cleanups done.
It also has a new feature which is useful for us to test distributed filesystem coherency with - you can optionally specify multiple pathnames that represent the same file (either different client mountpoints, and/or the same file opened multiple times in the same mountpoint). Then fsx will do sequential operations across all of them in a random or round-robin manner. This is a good test for cache coherency, mmap, etc.
I'm not aware of any "upstream" fsx maintainer, so LTP seemed as good a place as any to send these updates.