Sorry to disturb you. But I have small comment about subject. I think it is unnecessary overload involve mount point in lookup for global cache. You save few bytes for hashhead for every mount point, but loose effectively lookup. Every lookup has one more compare for mp, and your hashtable will be more bigger. In any case have hashhead and hashlock for every mount point is more flexible way, IMHO. "struct mount" is a good place for this.
Ilia.
