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 bool __blk_end_bidi_request(struct request *rq, int error,
  21                             unsigned int nr_bytes, unsigned int bidi_bytes);
  22
  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 succeeds
  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 void blk_insert_flush(struct request *rq);
  55 void blk_abort_flushes(struct request_queue *q);
  56
  57 static inline struct request *__elv_next_request(struct request_queue *q)
  58 {
  59         struct request *rq;
  60
  61         while (1) {
  62                 if (!list_empty(&q->queue_head)) {
  63                         rq = list_entry_rq(q->queue_head.next);
  64                         return rq;
  65                 }
  66
  67                 /*
  68                  * Flush request is running and flush request isn't queueable
  69                  * in the drive, we can hold the queue till flush request is
  70                  * finished. Even we don't do this, driver can't dispatch next
  71                  * requests and will requeue them. And this can improve
  72                  * throughput too. For example, we have request flush1, write1,
  73                  * flush 2. flush1 is dispatched, then queue is hold, write1
  74                  * isn't inserted to queue. After flush1 is finished, flush2
  75                  * will be dispatched. Since disk cache is already clean,
  76                  * flush2 will be finished very soon, so looks like flush2 is
  77                  * folded to flush1.
  78                  * Since the queue is hold, a flag is set to indicate the queue
  79                  * should be restarted later. Please see flush_end_io() for
  80                  * details.
  81                  */
  82                 if (q->flush_pending_idx != q->flush_running_idx &&
  83                                 !queue_flush_queueable(q)) {
  84                         q->flush_queue_delayed = 1;
  85                         return NULL;
  86                 }
  87                 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
  88                     !q->elevator->ops->elevator_dispatch_fn(q, 0))
  89                         return NULL;
  90         }
  91 }
  92
  93 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  94 {
  95         struct elevator_queue *e = q->elevator;
  96
  97         if (e->ops->elevator_activate_req_fn)
  98                 e->ops->elevator_activate_req_fn(q, rq);
  99 }
 100
 101 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 102 {
 103         struct elevator_queue *e = q->elevator;
 104
 105         if (e->ops->elevator_deactivate_req_fn)
 106                 e->ops->elevator_deactivate_req_fn(q, rq);
 107 }
 108
 109 #ifdef CONFIG_FAIL_IO_TIMEOUT
 110 int blk_should_fake_timeout(struct request_queue *);
 111 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 112 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 113                                 const char *, size_t);
 114 #else
 115 static inline int blk_should_fake_timeout(struct request_queue *q)
 116 {
 117         return 0;
 118 }
 119 #endif
 120
 121 struct io_context *current_io_context(gfp_t gfp_flags, int node);
 122
 123 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 124                      struct bio *bio);
 125 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 126                       struct bio *bio);
 127 int attempt_back_merge(struct request_queue *q, struct request *rq);
 128 int attempt_front_merge(struct request_queue *q, struct request *rq);
 129 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 130                                 struct request *next);
 131 void blk_recalc_rq_segments(struct request *rq);
 132 void blk_rq_set_mixed_merge(struct request *rq);
 133
 134 void blk_queue_congestion_threshold(struct request_queue *q);
 135
 136 int blk_dev_init(void);
 137
 138 void elv_quiesce_start(struct request_queue *q);
 139 void elv_quiesce_end(struct request_queue *q);
 140
 141
 142 /*
 143  * Return the threshold (number of used requests) at which the queue is
 144  * considered to be congested.  It include a little hysteresis to keep the
 145  * context switch rate down.
 146  */
 147 static inline int queue_congestion_on_threshold(struct request_queue *q)
 148 {
 149         return q->nr_congestion_on;
 150 }
 151
 152 /*
 153  * The threshold at which a queue is considered to be uncongested
 154  */
 155 static inline int queue_congestion_off_threshold(struct request_queue *q)
 156 {
 157         return q->nr_congestion_off;
 158 }
 159
 160 static inline int blk_cpu_to_group(int cpu)
 161 {
 162         int group = NR_CPUS;
 163 #ifdef CONFIG_SCHED_MC
 164         const struct cpumask *mask = cpu_coregroup_mask(cpu);
 165         group = cpumask_first(mask);
 166 #elif defined(CONFIG_SCHED_SMT)
 167         group = cpumask_first(topology_thread_cpumask(cpu));
 168 #else
 169         return cpu;
 170 #endif
 171         if (likely(group < NR_CPUS))
 172                 return group;
 173         return cpu;
 174 }
 175
 176 /*
 177  * Contribute to IO statistics IFF:
 178  *
 179  *      a) it's attached to a gendisk, and
 180  *      b) the queue had IO stats enabled when this request was started, and
 181  *      c) it's a file system request or a discard request
 182  */
 183 static inline int blk_do_io_stat(struct request *rq)
 184 {
 185         return rq->rq_disk &&
 186                (rq->cmd_flags & REQ_IO_STAT) &&
 187                (rq->cmd_type == REQ_TYPE_FS ||
 188                 (rq->cmd_flags & REQ_DISCARD));
 189 }
 190
 191 #endif