Provided by: kernel-doc-2.4.27_2.4.27-12_all bug


       blk_queue_headactive  -   indicate whether head of request queue may be


       void blk_queue_headactive (request_queue_t *q, int active);


       q                  The queue which this applies to.

       active        A flag indication where the head of the queue is  active.


       The  driver for a block device may choose to leave the currently active
       request on the request queue, removing it only when it  has  completed.
       The  queue  handling routines assume this by default for safety reasons
       and will not involve the head of the request queue in  any  merging  or
       reordering  of  requests  when  the queue is unplugged (and thus may be
       working on this particular request).

       If a driver removes requests from the  queue  before  processing  them,
       then it may indicate that it does so, there by allowing the head of the
       queue to be involved in  merging  and  reordering.   This  is  done  be
       calling blk_queue_headactive with an active flag of 0.

       If a driver processes several requests at once, it must remove them (or
       at least all but one of them) from the request queue.

       When a queue is plugged the head will be assumed to be inactive.