where is disk block access in kernel ?

[Ran Shalit]

Hello,

I would like to monitor the write access to disk blocks (so that I can
monitor the block index in some bitmap)
I think this must be done in kernel (userspace have no such information)
I have tried to search in kernel but did not found where is the API to
access disk blocks.
There is libata-core.c , but I can't find such routines there, and
neither any documentation.

Is there any idea ?

Regards,
Ran