Not sure if I missunderstand you but I am _not_ suggesting pushing any state into p9.
My thoughts where modifying cfs heuristics to reduce the probability of waiting for a coherence check (which could be quite a few RTTs).
We're on the same track. This stuff would fit in cfs just as easily. What I'm curious about is if a 'the file was modified' callback would help -- basically, just a notification to flush the cache, which would let the client be more aggressive about holding blocks in the cache without having to ping the server on every read.
9P wouldn't need any mods -- this would work easily as a filter pushed on the 9fs connection. But it would need a callback facility to notify the server side of the cache filter that the file had changed.
--lyndon
