block/blk.h

   1 #ifndef BLK_INTERNAL_H
   2 #define BLK_INTERNAL_H
   3
   4 #include <linux/idr.h>
   5
   6 /* Amount of time in which a process may batch requests */
   7 #define BLK_BATCH_TIME  (HZ/50UL)
   8
   9 /* Number of requests a "batching" process may submit */
  10 #define BLK_BATCH_REQ   32
  11
  12 extern struct kmem_cache *blk_requestq_cachep;
  13 extern struct kobj_type blk_queue_ktype;
  14 extern struct ida blk_queue_ida;
  15
  16 void init_request_from_bio(struct request *req, struct bio *bio);
  17 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  18                         struct bio *bio);
  19 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  20                       struct bio *bio);
  21 void blk_drain_queue(struct request_queue *q, bool drain_all);
  22 void blk_dequeue_request(struct request *rq);
  23 void __blk_queue_free_tags(struct request_queue *q);
  24 bool __blk_end_bidi_request(struct request *rq, int error,
  25                             unsigned int nr_bytes, unsigned int bidi_bytes);
  26
  27 void blk_rq_timed_out_timer(unsigned long data);
  28 void blk_delete_timer(struct request *);
  29 void blk_add_timer(struct request *);
  30 void __generic_unplug_device(struct request_queue *);
  31
  32 /*
  33  * Internal atomic flags for request handling
  34  */
  35 enum rq_atomic_flags {
  36         REQ_ATOM_COMPLETE = 0,
  37 };
  38
  39 /*
  40  * EH timer and IO completion will both attempt to 'grab' the request, make
  41  * sure that only one of them succeeds
  42  */
  43 static inline int blk_mark_rq_complete(struct request *rq)
  44 {
  45         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  46 }
  47
  48 static inline void blk_clear_rq_complete(struct request *rq)
  49 {
  50         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  51 }
  52
  53 /*
  54  * Internal elevator interface
  55  */
  56 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  57
  58 void blk_insert_flush(struct request *rq);
  59 void blk_abort_flushes(struct request_queue *q);
  60
  61 static inline struct request *__elv_next_request(struct request_queue *q)
  62 {
  63         struct request *rq;
  64
  65         while (1) {
  66                 if (!list_empty(&q->queue_head)) {
  67                         rq = list_entry_rq(q->queue_head.next);
  68                         return rq;
  69                 }
  70
  71                 /*
  72                  * Flush request is running and flush request isn't queueable
  73                  * in the drive, we can hold the queue till flush request is
  74                  * finished. Even we don't do this, driver can't dispatch next
  75                  * requests and will requeue them. And this can improve
  76                  * throughput too. For example, we have request flush1, write1,
  77                  * flush 2. flush1 is dispatched, then queue is hold, write1
  78                  * isn't inserted to queue. After flush1 is finished, flush2
  79                  * will be dispatched. Since disk cache is already clean,
  80                  * flush2 will be finished very soon, so looks like flush2 is
  81                  * folded to flush1.
  82                  * Since the queue is hold, a flag is set to indicate the queue
  83                  * should be restarted later. Please see flush_end_io() for
  84                  * details.
  85                  */
  86                 if (q->flush_pending_idx != q->flush_running_idx &&
  87                                 !queue_flush_queueable(q)) {
  88                         q->flush_queue_delayed = 1;
  89                         return NULL;
  90                 }
  91                 if (unlikely(blk_queue_dead(q)) ||
  92                     !q->elevator->ops->elevator_dispatch_fn(q, 0))
  93                         return NULL;
  94         }
  95 }
  96
  97 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  98 {
  99         struct elevator_queue *e = q->elevator;
 100
 101         if (e->ops->elevator_activate_req_fn)
 102                 e->ops->elevator_activate_req_fn(q, rq);
 103 }
 104
 105 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 106 {
 107         struct elevator_queue *e = q->elevator;
 108
 109         if (e->ops->elevator_deactivate_req_fn)
 110                 e->ops->elevator_deactivate_req_fn(q, rq);
 111 }
 112
 113 #ifdef CONFIG_FAIL_IO_TIMEOUT
 114 int blk_should_fake_timeout(struct request_queue *);
 115 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 116 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 117                                 const char *, size_t);
 118 #else
 119 static inline int blk_should_fake_timeout(struct request_queue *q)
 120 {
 121         return 0;
 122 }
 123 #endif
 124
 125 struct io_context *current_io_context(gfp_t gfp_flags, int node);
 126
 127 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 128                      struct bio *bio);
 129 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 130                       struct bio *bio);
 131 int attempt_back_merge(struct request_queue *q, struct request *rq);
 132 int attempt_front_merge(struct request_queue *q, struct request *rq);
 133 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 134                                 struct request *next);
 135 void blk_recalc_rq_segments(struct request *rq);
 136 void blk_rq_set_mixed_merge(struct request *rq);
 137
 138 void blk_queue_congestion_threshold(struct request_queue *q);
 139
 140 int blk_dev_init(void);
 141
 142 void elv_quiesce_start(struct request_queue *q);
 143 void elv_quiesce_end(struct request_queue *q);
 144
 145
 146 /*
 147  * Return the threshold (number of used requests) at which the queue is
 148  * considered to be congested.  It include a little hysteresis to keep the
 149  * context switch rate down.
 150  */
 151 static inline int queue_congestion_on_threshold(struct request_queue *q)
 152 {
 153         return q->nr_congestion_on;
 154 }
 155
 156 /*
 157  * The threshold at which a queue is considered to be uncongested
 158  */
 159 static inline int queue_congestion_off_threshold(struct request_queue *q)
 160 {
 161         return q->nr_congestion_off;
 162 }
 163
 164 static inline int blk_cpu_to_group(int cpu)
 165 {
 166         int group = NR_CPUS;
 167 #ifdef CONFIG_SCHED_MC
 168         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 169         group = cpumask_first(mask);
 170 #elif defined(CONFIG_SCHED_SMT)
 171         group = cpumask_first(topology_thread_cpumask(cpu));
 172 #else
 173         return cpu;
 174 #endif
 175         if (likely(group < NR_CPUS))
 176                 return group;
 177         return cpu;
 178 }
 179
 180 /*
 181  * Contribute to IO statistics IFF:
 182  *
 183  *      a) it's attached to a gendisk, and
 184  *      b) the queue had IO stats enabled when this request was started, and
 185  *      c) it's a file system request or a discard request
 186  */
 187 static inline int blk_do_io_stat(struct request *rq)
 188 {
 189         return rq->rq_disk &&
 190                (rq->cmd_flags & REQ_IO_STAT) &&
 191                (rq->cmd_type == REQ_TYPE_FS ||
 192                 (rq->cmd_flags & REQ_DISCARD));
 193 }
 194
 195 #ifdef CONFIG_BLK_DEV_THROTTLING
 196 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 197 extern void blk_throtl_drain(struct request_queue *q);
 198 extern int blk_throtl_init(struct request_queue *q);
 199 extern void blk_throtl_exit(struct request_queue *q);
 200 extern void blk_throtl_release(struct request_queue *q);
 201 #else /* CONFIG_BLK_DEV_THROTTLING */
 202 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 203 {
 204         return false;
 205 }
 206 static inline void blk_throtl_drain(struct request_queue *q) { }
 207 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 208 static inline void blk_throtl_exit(struct request_queue *q) { }
 209 static inline void blk_throtl_release(struct request_queue *q) { }
 210 #endif /* CONFIG_BLK_DEV_THROTTLING */
 211
 212 #endif /* BLK_INTERNAL_H */