Name
blk_queue_prep_rq — 
  set a prepare_request function for queue
 
Synopsis
| void blk_queue_prep_rq ( | struct request_queue * q, | 
|  | prep_rq_fn * pfn ); | 
 
Arguments
- q
- 
     queue
     
- pfn
- 
     prepare_request function
     
Description
   It's possible for a queue to register a prepare_request callback which
   is invoked before the request is handed to the request_fn. The goal of
   the function is to prepare a request for I/O, it can be used to build a
   cdb from the request data for instance.