Incorporating a small change in inode structure: please help

[Kaustubh Ghosh]

Hi all,
    what I want is to incorporate one extra field of information in the inode 
structure. Can anybody tell me where I will find the definition of inode so 
that I can add the extra field.What will be the other causes of concern, and 
what more functions accessing the inodes will I need to change?
Thanks in advance.
I looked under fs  in the kernel source, found inode.c requires some 
updation(If anyone please point out what functions should I change there -it 
would still help me immensely).But what I was unable to find is the inode 
definition.Please help me.

Thanks for any help that you  can give .