Currently, when the user issues a partial page read/write, Lustre (including client side and server side) will convert it into a full page read/write.

This is not efficient for small read/write operations , say if you want to read/write several bytes from a file, actually Lustre will  read/write a full page. This will become even worse for large PAGE_SIZE 64KB.

Make Lustre do a real partial page read/write which the read/write range is actual from start to end(which are given by the user), so that we can get an efficient small read/write.