b=201

b=201
b=285
- Added generation numbers to MDS locks (still need to for OSC locks, bug 294)
- fixup the inode pointer in the ldlm_lock after intent gives us a lock on a
  different resource (bug 285)
- cancel locks when the inodes are flushed from the cache (bug 201)
- fix serious cache coherancy bugs by really tying locks to dentries:
  - always return 0 from revalidate2 for a negative dentry, forcing lookup2
  - when MDS locks are cancelled, unhash the associated dentries (but do NOT
    remove them from the aliases list)
    - avoid calling the cancellation callback at shutdown and clear_inode time,
      by adding yet another flag, this time to cancel_unused
  - lookup2 searches for old dentries that may satisfy a new request, and may
    reuse a dentry that we previously unhashed

We broke hard links even more than they were before--you've been warned!