Branch: b_new_cmd

Branch: b_new_cmd
1) revert back the last commit for cancel the update lock of cross-ref object,
   since the following revalidate may need this lock.
2) set l_ast_data for the update lock in readdir, since it may not be set for the
   for the cross-object.
3) in ll_revalidate_inode_it, we should only try to get GETATTR lock.