code: void addToInvalidates(Block b, DatanodeInfo n, boolean ackRequired) {
      addToInvalidatesNoLog(b, n, ackRequired);
      if (isInitialized && !isInSafeModeInternal()) {
        // do not log in startup phase
        NameNode.stateChangeLog.info("BLOCK* NameSystem.addToInvalidates: "
          + b.getBlockName() + " is added to invalidSet of " + n.getName());
      }
    }
docs: Adds block to list of blocks which will be invalidated on
  specified datanode and log the move
  
  @param b block
  @param n datanode