7656 unlinking directory on tmpfs can cause kernel panic

*** 1103,1114 ****
          rw_enter(&parent->tn_rwlock, RW_WRITER);
          rw_enter(&tp->tn_rwlock, RW_WRITER);
  
          if (tp->tn_type != VDIR ||
              (error = secpolicy_fs_linkdir(cred, dvp->v_vfsp)) == 0)
!                 error = tdirdelete(parent, tp, nm, tp->tn_type == VDIR ?
!                     DR_RMDIR : DR_REMOVE, cred);
  
          rw_exit(&tp->tn_rwlock);
          rw_exit(&parent->tn_rwlock);
          vnevent_remove(TNTOV(tp), dvp, nm, ct);
          tmpnode_rele(tp);
--- 1103,1113 ----
          rw_enter(&parent->tn_rwlock, RW_WRITER);
          rw_enter(&tp->tn_rwlock, RW_WRITER);
  
          if (tp->tn_type != VDIR ||
              (error = secpolicy_fs_linkdir(cred, dvp->v_vfsp)) == 0)
!                 error = tdirdelete(parent, tp, nm, DR_REMOVE, cred);
  
          rw_exit(&tp->tn_rwlock);
          rw_exit(&parent->tn_rwlock);
          vnevent_remove(TNTOV(tp), dvp, nm, ct);
          tmpnode_rele(tp);