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 rq_init(struct request_queue *q, struct request *rq);
  14 void init_request_from_bio(struct request *req, struct bio *bio);
  15 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  16                         struct bio *bio);
  17 void __blk_queue_free_tags(struct request_queue *q);
  18
  19 void blk_unplug_work(struct work_struct *work);
  20 void blk_unplug_timeout(unsigned long data);
  21
  22 struct io_context *current_io_context(gfp_t gfp_flags, int node);
  23
  24 int ll_back_merge_fn(struct request_queue *q, struct request *req,
  25                      struct bio *bio);
  26 int ll_front_merge_fn(struct request_queue *q, struct request *req,
  27                       struct bio *bio);
  28 int attempt_back_merge(struct request_queue *q, struct request *rq);
  29 int attempt_front_merge(struct request_queue *q, struct request *rq);
  30 void blk_recalc_rq_segments(struct request *rq);
  31 void blk_recalc_rq_sectors(struct request *rq, int nsect);
  32
  33 void blk_queue_congestion_threshold(struct request_queue *q);
  34
  35 /*
  36  * Return the threshold (number of used requests) at which the queue is
  37  * considered to be congested.  It include a little hysteresis to keep the
  38  * context switch rate down.
  39  */
  40 static inline int queue_congestion_on_threshold(struct request_queue *q)
  41 {
  42         return q->nr_congestion_on;
  43 }
  44
  45 /*
  46  * The threshold at which a queue is considered to be uncongested
  47  */
  48 static inline int queue_congestion_off_threshold(struct request_queue *q)
  49 {
  50         return q->nr_congestion_off;
  51 }
  52
  53 #endif