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 static inline struct request *__elv_next_request(struct request_queue *q)
  55 {
  56         struct request *rq;
  57
  58         while (1) {
  59                 while (!list_empty(&q->queue_head)) {
  60                         rq = list_entry_rq(q->queue_head.next);
  61                         if (blk_do_ordered(q, &rq))
  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 void blk_recalc_rq_segments(struct request *rq);
 107 void blk_rq_set_mixed_merge(struct request *rq);
 108
 109 void blk_queue_congestion_threshold(struct request_queue *q);
 110
 111 int blk_dev_init(void);
 112
 113 void elv_quiesce_start(struct request_queue *q);
 114 void elv_quiesce_end(struct request_queue *q);
 115
 116
 117 /*
 118  * Return the threshold (number of used requests) at which the queue is
 119  * considered to be congested.  It include a little hysteresis to keep the
 120  * context switch rate down.
 121  */
 122 static inline int queue_congestion_on_threshold(struct request_queue *q)
 123 {
 124         return q->nr_congestion_on;
 125 }
 126
 127 /*
 128  * The threshold at which a queue is considered to be uncongested
 129  */
 130 static inline int queue_congestion_off_threshold(struct request_queue *q)
 131 {
 132         return q->nr_congestion_off;
 133 }
 134
 135 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 136
 137 #define rq_for_each_integrity_segment(bvl, _rq, _iter)          \
 138         __rq_for_each_bio(_iter.bio, _rq)                       \
 139                 bip_for_each_vec(bvl, _iter.bio->bi_integrity, _iter.i)
 140
 141 #endif /* BLK_DEV_INTEGRITY */
 142
 143 static inline int blk_cpu_to_group(int cpu)
 144 {
 145         int group = NR_CPUS;
 146 #ifdef CONFIG_SCHED_MC
 147         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 148         group = cpumask_first(mask);
 149 #elif defined(CONFIG_SCHED_SMT)
 150         group = cpumask_first(topology_thread_cpumask(cpu));
 151 #else
 152         return cpu;
 153 #endif
 154         if (likely(group < NR_CPUS))
 155                 return group;
 156         return cpu;
 157 }
 158
 159 /*
 160  * Contribute to IO statistics IFF:
 161  *
 162  *      a) it's attached to a gendisk, and
 163  *      b) the queue had IO stats enabled when this request was started, and
 164  *      c) it's a file system request or a discard request
 165  */
 166 static inline int blk_do_io_stat(struct request *rq)
 167 {
 168         return rq->rq_disk &&
 169                (rq->cmd_flags & REQ_IO_STAT) &&
 170                (rq->cmd_type == REQ_TYPE_FS ||
 171                 (rq->cmd_flags & REQ_DISCARD));
 172 }
 173
 174 #endif