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