Mounting a dev with indexed hashing support

Hi all

I created a logical Volume and tried to format it with ext2 filesystem.
When I tried to mount it using -o index option for enabling hash-indexing support it failed saying unsupported option. I tried both in 2.4 and 2.6 kernels. Do we need to enable any support in the kernel for this.

This may seem unusual in this list . But please give me some pointers
where to look in to.

Thanks
John