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                  * Flush request is running and flush request isn't queueable
  66                  * in the drive, we can hold the queue till flush request is
  67                  * finished. Even we don't do this, driver can't dispatch next
  68                  * requests and will requeue them. And this can improve
  69                  * throughput too. For example, we have request flush1, write1,
  70                  * flush 2. flush1 is dispatched, then queue is hold, write1
  71                  * isn't inserted to queue. After flush1 is finished, flush2
  72                  * will be dispatched. Since disk cache is already clean,
  73                  * flush2 will be finished very soon, so looks like flush2 is
  74                  * folded to flush1.
  75                  * Since the queue is hold, a flag is set to indicate the queue
  76                  * should be restarted later. Please see flush_end_io() for
  77                  * details.
  78                  */
  79                 if (q->flush_pending_idx != q->flush_running_idx &&
  80                                 !queue_flush_queueable(q)) {
  81                         q->flush_queue_delayed = 1;
  82                         return NULL;
  83                 }
  84                 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
  85                     !q->elevator->ops->elevator_dispatch_fn(q, 0))
  86                         return NULL;
  87         }
  88 }
  89
  90 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  91 {
  92         struct elevator_queue *e = q->elevator;
  93
  94         if (e->ops->elevator_activate_req_fn)
  95                 e->ops->elevator_activate_req_fn(q, rq);
  96 }
  97
  98 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
  99 {
 100         struct elevator_queue *e = q->elevator;
 101
 102         if (e->ops->elevator_deactivate_req_fn)
 103                 e->ops->elevator_deactivate_req_fn(q, rq);
 104 }
 105
 106 #ifdef CONFIG_FAIL_IO_TIMEOUT
 107 int blk_should_fake_timeout(struct request_queue *);
 108 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 109 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 110                                 const char *, size_t);
 111 #else
 112 static inline int blk_should_fake_timeout(struct request_queue *q)
 113 {
 114         return 0;
 115 }
 116 #endif
 117
 118 struct io_context *current_io_context(gfp_t gfp_flags, int node);
 119
 120 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 121                      struct bio *bio);
 122 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 123                       struct bio *bio);
 124 int attempt_back_merge(struct request_queue *q, struct request *rq);
 125 int attempt_front_merge(struct request_queue *q, struct request *rq);
 126 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 127                                 struct request *next);
 128 void blk_recalc_rq_segments(struct request *rq);
 129 void blk_rq_set_mixed_merge(struct request *rq);
 130
 131 void blk_queue_congestion_threshold(struct request_queue *q);
 132
 133 int blk_dev_init(void);
 134
 135 void elv_quiesce_start(struct request_queue *q);
 136 void elv_quiesce_end(struct request_queue *q);
 137
 138
 139 /*
 140  * Return the threshold (number of used requests) at which the queue is
 141  * considered to be congested.  It include a little hysteresis to keep the
 142  * context switch rate down.
 143  */
 144 static inline int queue_congestion_on_threshold(struct request_queue *q)
 145 {
 146         return q->nr_congestion_on;
 147 }
 148
 149 /*
 150  * The threshold at which a queue is considered to be uncongested
 151  */
 152 static inline int queue_congestion_off_threshold(struct request_queue *q)
 153 {
 154         return q->nr_congestion_off;
 155 }
 156
 157 static inline int blk_cpu_to_group(int cpu)
 158 {
 159         int group = NR_CPUS;
 160 #ifdef CONFIG_SCHED_MC
 161         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 162         group = cpumask_first(mask);
 163 #elif defined(CONFIG_SCHED_SMT)
 164         group = cpumask_first(topology_thread_cpumask(cpu));
 165 #else
 166         return cpu;
 167 #endif
 168         if (likely(group < NR_CPUS))
 169                 return group;
 170         return cpu;
 171 }
 172
 173 /*
 174  * Contribute to IO statistics IFF:
 175  *
 176  *      a) it's attached to a gendisk, and
 177  *      b) the queue had IO stats enabled when this request was started, and
 178  *      c) it's a file system request or a discard request
 179  */
 180 static inline int blk_do_io_stat(struct request *rq)
 181 {
 182         return rq->rq_disk &&
 183                (rq->cmd_flags & REQ_IO_STAT) &&
 184                (rq->cmd_type == REQ_TYPE_FS ||
 185                 (rq->cmd_flags & REQ_DISCARD));
 186 }
 187
 188 #endif