block/blk.h

   1 #ifndef BLK_INTERNAL_H
   2 #define BLK_INTERNAL_H
   3
   4 /* Amount of time in which a process may batch requests */
   5 #define BLK_BATCH_TIME  (HZ/50UL)
   6
   7 /* Number of requests a "batching" process may submit */
   8 #define BLK_BATCH_REQ   32
   9
  10 extern struct kmem_cache *blk_requestq_cachep;
  11 extern struct kobj_type blk_queue_ktype;
  12
  13 void init_request_from_bio(struct request *req, struct bio *bio);
  14 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  15                         struct bio *bio);
  16 void __blk_queue_free_tags(struct request_queue *q);
  17
  18 void blk_unplug_work(struct work_struct *work);
  19 void blk_unplug_timeout(unsigned long data);
  20
  21 struct io_context *current_io_context(gfp_t gfp_flags, int node);
  22
  23 int ll_back_merge_fn(struct request_queue *q, struct request *req,
  24                      struct bio *bio);
  25 int ll_front_merge_fn(struct request_queue *q, struct request *req,
  26                       struct bio *bio);
  27 int attempt_back_merge(struct request_queue *q, struct request *rq);
  28 int attempt_front_merge(struct request_queue *q, struct request *rq);
  29 void blk_recalc_rq_segments(struct request *rq);
  30 void blk_recalc_rq_sectors(struct request *rq, int nsect);
  31
  32 void blk_queue_congestion_threshold(struct request_queue *q);
  33
  34 int blk_dev_init(void);
  35
  36 /*
  37  * Return the threshold (number of used requests) at which the queue is
  38  * considered to be congested.  It include a little hysteresis to keep the
  39  * context switch rate down.
  40  */
  41 static inline int queue_congestion_on_threshold(struct request_queue *q)
  42 {
  43         return q->nr_congestion_on;
  44 }
  45
  46 /*
  47  * The threshold at which a queue is considered to be uncongested
  48  */
  49 static inline int queue_congestion_off_threshold(struct request_queue *q)
  50 {
  51         return q->nr_congestion_off;
  52 }
  53
  54 #endif