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_ordered(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                         rq = blk_do_ordered(q, rq);
  64                         if (rq)
  65                                 return rq;
  66                 }
  67
  68                 if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
  69                         return NULL;
  70         }
  71 }
  72
  73 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  74 {
  75         struct elevator_queue *e = q->elevator;
  76
  77         if (e->ops->elevator_activate_req_fn)
  78                 e->ops->elevator_activate_req_fn(q, rq);
  79 }
  80
  81 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
  82 {
  83         struct elevator_queue *e = q->elevator;
  84
  85         if (e->ops->elevator_deactivate_req_fn)
  86                 e->ops->elevator_deactivate_req_fn(q, rq);
  87 }
  88
  89 #ifdef CONFIG_FAIL_IO_TIMEOUT
  90 int blk_should_fake_timeout(struct request_queue *);
  91 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
  92 ssize_t part_timeout_store(struct device *, struct device_attribute *,
  93                                 const char *, size_t);
  94 #else
  95 static inline int blk_should_fake_timeout(struct request_queue *q)
  96 {
  97         return 0;
  98 }
  99 #endif
 100
 101 struct io_context *current_io_context(gfp_t gfp_flags, int node);
 102
 103 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 104                      struct bio *bio);
 105 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 106                       struct bio *bio);
 107 int attempt_back_merge(struct request_queue *q, struct request *rq);
 108 int attempt_front_merge(struct request_queue *q, struct request *rq);
 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 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 139
 140 #define rq_for_each_integrity_segment(bvl, _rq, _iter)          \
 141         __rq_for_each_bio(_iter.bio, _rq)                       \
 142                 bip_for_each_vec(bvl, _iter.bio->bi_integrity, _iter.i)
 143
 144 #endif /* BLK_DEV_INTEGRITY */
 145
 146 static inline int blk_cpu_to_group(int cpu)
 147 {
 148 #ifdef CONFIG_SCHED_MC
 149         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 150         return cpumask_first(mask);
 151 #elif defined(CONFIG_SCHED_SMT)
 152         return cpumask_first(topology_thread_cpumask(cpu));
 153 #else
 154         return cpu;
 155 #endif
 156 }
 157
 158 /*
 159  * Contribute to IO statistics IFF:
 160  *
 161  *      a) it's attached to a gendisk, and
 162  *      b) the queue had IO stats enabled when this request was started, and
 163  *      c) it's a file system request or a discard request
 164  */
 165 static inline int blk_do_io_stat(struct request *rq)
 166 {
 167         return rq->rq_disk &&
 168                (rq->cmd_flags & REQ_IO_STAT) &&
 169                (rq->cmd_type == REQ_TYPE_FS ||
 170                 (rq->cmd_flags & REQ_DISCARD));
 171 }
 172
 173 #endif