mem_segment_t related doubt

[Sabarinathan <nsnsabari@xxxxxxxxx>]

Hi,
I am writing a kernel module
in the following lines of my code:
mem_segment_t old_fs=get_fs();
set_fs(get_ds());
/* code for sock_recvmsg */
set_fs(old_fs);

I am getting mem_segment_t as declared 
I am unable to find its location 
I am using kernel 2.4

plz help me to resolve this

Regards
Sabari