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