how to use HA_NO_COPY_ON_ALTER on my storage engine?

[xiao.feng]

Hi,
 My storage engine kernel support add/drop column without copy data from one to one;
 I set HA_NO_COPY_ON_ALTER on table flag.
 when I add a column an table abc.
 it create temptable t1 with new table flags, and then rename abc to t2.
 then rename t1 to abc, at last it drop t2.
 these doesn't remain any data on table abc.

 how to use HA_NO_COPY_ON_ALTER on my storage engine?