what differience between ll_rw_block and readpage
 

hi, recently days I confused about ll_rw_block(READ,...) and readpage methods. They all requests low level to issue disk IO. But what the difference between them. Just the block_read_full_page use a page to contains more wanted buffers? And they all invoked submit_bh(), are there hierarchical relations between them, if so, why readpage not invoke ll_rw_block iteratively?

Thanks.