MDCache: make linkunlink rstat propagation work properly.
MDCache: make linkunlink rstat propagation work properly.

We could be in a lock state (ie, gather) where we can't take new locks.
But if we're in this function for linkunlink we have to already have
a lock, so in that case make sure the function succeeds and assert
that we do have a lock.

Signed-off-by: Greg Farnum <0bcb4295d38ee745130ea5f2bb88ef4eef474e61@dreamhost.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph