namecache final status report

[Gleb Kurtsou]

Initial project goals are now completed.

I've just finished weak-only cache support, which is to resemble current cache
behaviour and to be used by networked filesystems. It still has stability
issues and the plan is to change a bit the way caching implemented (notably
MAKEENTRY flag) to make weak-only cache support easier within dircache.

It was also decided not to add "namespace" concept to cache, because it's
possible to open a file with fhopen(2), i.e. without using file path.
"Namespace" is intended to support 'mount -o bind' style mounting and guarantee
consistent names and paths in cache. Adding it would require complete VFS
redesign.

"Strong" dircache needs more testing to work correctly for vnodes created with
VFS_VGET (NFS server use case). It's fully functional, but needs more work to
improve performance and profile locking.

I'm going to continue working on the project after Summer Of Code.

Thanks,
Gleb.