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_unplug_work(struct work_struct *work);
  22 void blk_unplug_timeout(unsigned long data);
  23 void blk_rq_timed_out_timer(unsigned long data);
  24 void blk_delete_timer(struct request *);
  25 void blk_add_timer(struct request *);
  26 void __generic_unplug_device(struct request_queue *);
  27
  28 /*
  29  * Internal atomic flags for request handling
  30  */
  31 enum rq_atomic_flags {
  32         REQ_ATOM_COMPLETE = 0,
  33 };
  34
  35 /*
  36  * EH timer and IO completion will both attempt to 'grab' the request, make
  37  * sure that only one of them suceeds
  38  */
  39 static inline int blk_mark_rq_complete(struct request *rq)
  40 {
  41         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  42 }
  43
  44 static inline void blk_clear_rq_complete(struct request *rq)
  45 {
  46         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  47 }
  48
  49 /*
  50  * Internal elevator interface
  51  */
  52 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  53
  54 struct request *blk_do_flush(struct request_queue *q, struct request *rq);
  55
  56 static inline struct request *__elv_next_request(struct request_queue *q)
  57 {
  58         struct request *rq;
  59
  60         while (1) {
  61                 while (!list_empty(&q->queue_head)) {
  62                         rq = list_entry_rq(q->queue_head.next);
  63                         if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) ||
  64                             rq == &q->flush_rq)
  65                                 return rq;
  66                         rq = blk_do_flush(q, rq);
  67                         if (rq)
  68                                 return rq;
  69                 }
  70
  71                 if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
  72                         return NULL;
  73         }
  74 }
  75
  76 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  77 {
  78         struct elevator_queue *e = q->elevator;
  79
  80         if (e->ops->elevator_activate_req_fn)
  81                 e->ops->elevator_activate_req_fn(q, rq);
  82 }
  83
  84 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
  85 {
  86         struct elevator_queue *e = q->elevator;
  87
  88         if (e->ops->elevator_deactivate_req_fn)
  89                 e->ops->elevator_deactivate_req_fn(q, rq);
  90 }
  91
  92 #ifdef CONFIG_FAIL_IO_TIMEOUT
  93 int blk_should_fake_timeout(struct request_queue *);
  94 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
  95 ssize_t part_timeout_store(struct device *, struct device_attribute *,
  96                                 const char *, size_t);
  97 #else
  98 static inline int blk_should_fake_timeout(struct request_queue *q)
  99 {
 100         return 0;
 101 }
 102 #endif
 103
 104 struct io_context *current_io_context(gfp_t gfp_flags, int node);
 105
 106 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 107                      struct bio *bio);
 108 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 109                       struct bio *bio);
 110 int attempt_back_merge(struct request_queue *q, struct request *rq);
 111 int attempt_front_merge(struct request_queue *q, struct request *rq);
 112 void blk_recalc_rq_segments(struct request *rq);
 113 void blk_rq_set_mixed_merge(struct request *rq);
 114
 115 void blk_queue_congestion_threshold(struct request_queue *q);
 116
 117 int blk_dev_init(void);
 118
 119 void elv_quiesce_start(struct request_queue *q);
 120 void elv_quiesce_end(struct request_queue *q);
 121
 122
 123 /*
 124  * Return the threshold (number of used requests) at which the queue is
 125  * considered to be congested.  It include a little hysteresis to keep the
 126  * context switch rate down.
 127  */
 128 static inline int queue_congestion_on_threshold(struct request_queue *q)
 129 {
 130         return q->nr_congestion_on;
 131 }
 132
 133 /*
 134  * The threshold at which a queue is considered to be uncongested
 135  */
 136 static inline int queue_congestion_off_threshold(struct request_queue *q)
 137 {
 138         return q->nr_congestion_off;
 139 }
 140
 141 static inline int blk_cpu_to_group(int cpu)
 142 {
 143         int group = NR_CPUS;
 144 #ifdef CONFIG_SCHED_MC
 145         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 146         group = cpumask_first(mask);
 147 #elif defined(CONFIG_SCHED_SMT)
 148         group = cpumask_first(topology_thread_cpumask(cpu));
 149 #else
 150         return cpu;
 151 #endif
 152         if (likely(group < NR_CPUS))
 153                 return group;
 154         return cpu;
 155 }
 156
 157 /*
 158  * Contribute to IO statistics IFF:
 159  *
 160  *      a) it's attached to a gendisk, and
 161  *      b) the queue had IO stats enabled when this request was started, and
 162  *      c) it's a file system request or a discard request
 163  */
 164 static inline int blk_do_io_stat(struct request *rq)
 165 {
 166         return rq->rq_disk &&
 167                (rq->cmd_flags & REQ_IO_STAT) &&
 168                (rq->cmd_type == REQ_TYPE_FS ||
 169                 (rq->cmd_flags & REQ_DISCARD));
 170 }
 171
 172 #endif