Block device invalidate cached blocks

[David Ashley]

I'm working on a block device driver for linux.

Linux caches the blocks read from my block device, which is fine. I've
mounted a read-only filesystem on the block device. But sometimes on
the back end the file system will change. Is there a way I can cause the
kernel to just flush all its cached blocks? Or even better invalidate
just the few blocks that have changed?

Thanks--
Dave