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_drain_queue(struct request_queue *q, bool drain_all);
  19 void blk_dequeue_request(struct request *rq);
  20 void __blk_queue_free_tags(struct request_queue *q);
  21 bool __blk_end_bidi_request(struct request *rq, int error,
  22                             unsigned int nr_bytes, unsigned int bidi_bytes);
  23
  24 void blk_rq_timed_out_timer(unsigned long data);
  25 void blk_delete_timer(struct request *);
  26 void blk_add_timer(struct request *);
  27 void __generic_unplug_device(struct request_queue *);
  28
  29 /*
  30  * Internal atomic flags for request handling
  31  */
  32 enum rq_atomic_flags {
  33         REQ_ATOM_COMPLETE = 0,
  34 };
  35
  36 /*
  37  * EH timer and IO completion will both attempt to 'grab' the request, make
  38  * sure that only one of them succeeds
  39  */
  40 static inline int blk_mark_rq_complete(struct request *rq)
  41 {
  42         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  43 }
  44
  45 static inline void blk_clear_rq_complete(struct request *rq)
  46 {
  47         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  48 }
  49
  50 /*
  51  * Internal elevator interface
  52  */
  53 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  54
  55 void blk_insert_flush(struct request *rq);
  56 void blk_abort_flushes(struct request_queue *q);
  57
  58 static inline struct request *__elv_next_request(struct request_queue *q)
  59 {
  60         struct request *rq;
  61
  62         while (1) {
  63                 if (!list_empty(&q->queue_head)) {
  64                         rq = list_entry_rq(q->queue_head.next);
  65                         return rq;
  66                 }
  67
  68                 /*
  69                  * Flush request is running and flush request isn't queueable
  70                  * in the drive, we can hold the queue till flush request is
  71                  * finished. Even we don't do this, driver can't dispatch next
  72                  * requests and will requeue them. And this can improve
  73                  * throughput too. For example, we have request flush1, write1,
  74                  * flush 2. flush1 is dispatched, then queue is hold, write1
  75                  * isn't inserted to queue. After flush1 is finished, flush2
  76                  * will be dispatched. Since disk cache is already clean,
  77                  * flush2 will be finished very soon, so looks like flush2 is
  78                  * folded to flush1.
  79                  * Since the queue is hold, a flag is set to indicate the queue
  80                  * should be restarted later. Please see flush_end_io() for
  81                  * details.
  82                  */
  83                 if (q->flush_pending_idx != q->flush_running_idx &&
  84                                 !queue_flush_queueable(q)) {
  85                         q->flush_queue_delayed = 1;
  86                         return NULL;
  87                 }
  88                 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
  89                     !q->elevator->ops->elevator_dispatch_fn(q, 0))
  90                         return NULL;
  91         }
  92 }
  93
  94 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  95 {
  96         struct elevator_queue *e = q->elevator;
  97
  98         if (e->ops->elevator_activate_req_fn)
  99                 e->ops->elevator_activate_req_fn(q, rq);
 100 }
 101
 102 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 103 {
 104         struct elevator_queue *e = q->elevator;
 105
 106         if (e->ops->elevator_deactivate_req_fn)
 107                 e->ops->elevator_deactivate_req_fn(q, rq);
 108 }
 109
 110 #ifdef CONFIG_FAIL_IO_TIMEOUT
 111 int blk_should_fake_timeout(struct request_queue *);
 112 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 113 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 114                                 const char *, size_t);
 115 #else
 116 static inline int blk_should_fake_timeout(struct request_queue *q)
 117 {
 118         return 0;
 119 }
 120 #endif
 121
 122 struct io_context *current_io_context(gfp_t gfp_flags, int node);
 123
 124 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 125                      struct bio *bio);
 126 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 127                       struct bio *bio);
 128 int attempt_back_merge(struct request_queue *q, struct request *rq);
 129 int attempt_front_merge(struct request_queue *q, struct request *rq);
 130 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 131                                 struct request *next);
 132 void blk_recalc_rq_segments(struct request *rq);
 133 void blk_rq_set_mixed_merge(struct request *rq);
 134
 135 void blk_queue_congestion_threshold(struct request_queue *q);
 136
 137 int blk_dev_init(void);
 138
 139 void elv_quiesce_start(struct request_queue *q);
 140 void elv_quiesce_end(struct request_queue *q);
 141
 142
 143 /*
 144  * Return the threshold (number of used requests) at which the queue is
 145  * considered to be congested.  It include a little hysteresis to keep the
 146  * context switch rate down.
 147  */
 148 static inline int queue_congestion_on_threshold(struct request_queue *q)
 149 {
 150         return q->nr_congestion_on;
 151 }
 152
 153 /*
 154  * The threshold at which a queue is considered to be uncongested
 155  */
 156 static inline int queue_congestion_off_threshold(struct request_queue *q)
 157 {
 158         return q->nr_congestion_off;
 159 }
 160
 161 static inline int blk_cpu_to_group(int cpu)
 162 {
 163         int group = NR_CPUS;
 164 #ifdef CONFIG_SCHED_MC
 165         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 166         group = cpumask_first(mask);
 167 #elif defined(CONFIG_SCHED_SMT)
 168         group = cpumask_first(topology_thread_cpumask(cpu));
 169 #else
 170         return cpu;
 171 #endif
 172         if (likely(group < NR_CPUS))
 173                 return group;
 174         return cpu;
 175 }
 176
 177 /*
 178  * Contribute to IO statistics IFF:
 179  *
 180  *      a) it's attached to a gendisk, and
 181  *      b) the queue had IO stats enabled when this request was started, and
 182  *      c) it's a file system request or a discard request
 183  */
 184 static inline int blk_do_io_stat(struct request *rq)
 185 {
 186         return rq->rq_disk &&
 187                (rq->cmd_flags & REQ_IO_STAT) &&
 188                (rq->cmd_type == REQ_TYPE_FS ||
 189                 (rq->cmd_flags & REQ_DISCARD));
 190 }
 191
 192 #ifdef CONFIG_BLK_DEV_THROTTLING
 193 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 194 extern void blk_throtl_drain(struct request_queue *q);
 195 extern int blk_throtl_init(struct request_queue *q);
 196 extern void blk_throtl_exit(struct request_queue *q);
 197 extern void blk_throtl_release(struct request_queue *q);
 198 #else /* CONFIG_BLK_DEV_THROTTLING */
 199 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 200 {
 201         return false;
 202 }
 203 static inline void blk_throtl_drain(struct request_queue *q) { }
 204 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 205 static inline void blk_throtl_exit(struct request_queue *q) { }
 206 static inline void blk_throtl_release(struct request_queue *q) { }
 207 #endif /* CONFIG_BLK_DEV_THROTTLING */
 208
 209 #endif /* BLK_INTERNAL_H */