Branch: b_new_cmd

Branch: b_new_cmd
Sometimes, we need revalidate dentries with (IT_CREATE/IT_OPEN), since
we did not unhash the cache totally on client for getpwd(2). so in
ll_revalidate_it we also need allocate the fid. If in mds, it did create
an object. then the dentry should be invalidate(return -ESTALE).
and some related cleanup work should be done in ll_revalidate_finish_it.