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 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  17                       struct bio *bio);
  18 void blk_dequeue_request(struct request *rq);
  19 void __blk_queue_free_tags(struct request_queue *q);
  20
  21 void blk_rq_timed_out_timer(unsigned long data);
  22 void blk_delete_timer(struct request *);
  23 void blk_add_timer(struct request *);
  24 void __generic_unplug_device(struct request_queue *);
  25
  26 /*
  27  * Internal atomic flags for request handling
  28  */
  29 enum rq_atomic_flags {
  30         REQ_ATOM_COMPLETE = 0,
  31 };
  32
  33 /*
  34  * EH timer and IO completion will both attempt to 'grab' the request, make
  35  * sure that only one of them succeeds
  36  */
  37 static inline int blk_mark_rq_complete(struct request *rq)
  38 {
  39         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  40 }
  41
  42 static inline void blk_clear_rq_complete(struct request *rq)
  43 {
  44         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  45 }
  46
  47 /*
  48  * Internal elevator interface
  49  */
  50 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  51
  52 void blk_insert_flush(struct request *rq);
  53 void blk_abort_flushes(struct request_queue *q);
  54
  55 static inline struct request *__elv_next_request(struct request_queue *q)
  56 {
  57         struct request *rq;
  58
  59         while (1) {
  60                 if (!list_empty(&q->queue_head)) {
  61                         rq = list_entry_rq(q->queue_head.next);
  62                         return rq;
  63                 }
  64
  65                 if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
  66                         return NULL;
  67         }
  68 }
  69
  70 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  71 {
  72         struct elevator_queue *e = q->elevator;
  73
  74         if (e->ops->elevator_activate_req_fn)
  75                 e->ops->elevator_activate_req_fn(q, rq);
  76 }
  77
  78 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
  79 {
  80         struct elevator_queue *e = q->elevator;
  81
  82         if (e->ops->elevator_deactivate_req_fn)
  83                 e->ops->elevator_deactivate_req_fn(q, rq);
  84 }
  85
  86 #ifdef CONFIG_FAIL_IO_TIMEOUT
  87 int blk_should_fake_timeout(struct request_queue *);
  88 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
  89 ssize_t part_timeout_store(struct device *, struct device_attribute *,
  90                                 const char *, size_t);
  91 #else
  92 static inline int blk_should_fake_timeout(struct request_queue *q)
  93 {
  94         return 0;
  95 }
  96 #endif
  97
  98 struct io_context *current_io_context(gfp_t gfp_flags, int node);
  99
 100 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 101                      struct bio *bio);
 102 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 103                       struct bio *bio);
 104 int attempt_back_merge(struct request_queue *q, struct request *rq);
 105 int attempt_front_merge(struct request_queue *q, struct request *rq);
 106 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 107                                 struct request *next);
 108 void blk_recalc_rq_segments(struct request *rq);
 109 void blk_rq_set_mixed_merge(struct request *rq);
 110
 111 void blk_queue_congestion_threshold(struct request_queue *q);
 112
 113 int blk_dev_init(void);
 114
 115 void elv_quiesce_start(struct request_queue *q);
 116 void elv_quiesce_end(struct request_queue *q);
 117
 118
 119 /*
 120  * Return the threshold (number of used requests) at which the queue is
 121  * considered to be congested.  It include a little hysteresis to keep the
 122  * context switch rate down.
 123  */
 124 static inline int queue_congestion_on_threshold(struct request_queue *q)
 125 {
 126         return q->nr_congestion_on;
 127 }
 128
 129 /*
 130  * The threshold at which a queue is considered to be uncongested
 131  */
 132 static inline int queue_congestion_off_threshold(struct request_queue *q)
 133 {
 134         return q->nr_congestion_off;
 135 }
 136
 137 static inline int blk_cpu_to_group(int cpu)
 138 {
 139         int group = NR_CPUS;
 140 #ifdef CONFIG_SCHED_MC
 141         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 142         group = cpumask_first(mask);
 143 #elif defined(CONFIG_SCHED_SMT)
 144         group = cpumask_first(topology_thread_cpumask(cpu));
 145 #else
 146         return cpu;
 147 #endif
 148         if (likely(group < NR_CPUS))
 149                 return group;
 150         return cpu;
 151 }
 152
 153 /*
 154  * Contribute to IO statistics IFF:
 155  *
 156  *      a) it's attached to a gendisk, and
 157  *      b) the queue had IO stats enabled when this request was started, and
 158  *      c) it's a file system request or a discard request
 159  */
 160 static inline int blk_do_io_stat(struct request *rq)
 161 {
 162         return rq->rq_disk &&
 163                (rq->cmd_flags & REQ_IO_STAT) &&
 164                (rq->cmd_type == REQ_TYPE_FS ||
 165                 (rq->cmd_flags & REQ_DISCARD));
 166 }
 167
 168 #endif