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 static inline void __blk_get_queue(struct request_queue *q)
  17 {
  18         kobject_get(&q->kobj);
  19 }
  20
  21 int blk_init_rl(struct request_list *rl, struct request_queue *q,
  22                 gfp_t gfp_mask);
  23 void blk_exit_rl(struct request_list *rl);
  24 void init_request_from_bio(struct request *req, struct bio *bio);
  25 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  26                         struct bio *bio);
  27 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  28                       struct bio *bio);
  29 void blk_queue_bypass_start(struct request_queue *q);
  30 void blk_queue_bypass_end(struct request_queue *q);
  31 void blk_dequeue_request(struct request *rq);
  32 void __blk_queue_free_tags(struct request_queue *q);
  33 bool __blk_end_bidi_request(struct request *rq, int error,
  34                             unsigned int nr_bytes, unsigned int bidi_bytes);
  35
  36 void blk_rq_timed_out_timer(unsigned long data);
  37 void blk_delete_timer(struct request *);
  38 void blk_add_timer(struct request *);
  39 void __generic_unplug_device(struct request_queue *);
  40
  41 /*
  42  * Internal atomic flags for request handling
  43  */
  44 enum rq_atomic_flags {
  45         REQ_ATOM_COMPLETE = 0,
  46 };
  47
  48 /*
  49  * EH timer and IO completion will both attempt to 'grab' the request, make
  50  * sure that only one of them succeeds
  51  */
  52 static inline int blk_mark_rq_complete(struct request *rq)
  53 {
  54         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  55 }
  56
  57 static inline void blk_clear_rq_complete(struct request *rq)
  58 {
  59         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  60 }
  61
  62 /*
  63  * Internal elevator interface
  64  */
  65 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  66
  67 void blk_insert_flush(struct request *rq);
  68 void blk_abort_flushes(struct request_queue *q);
  69
  70 static inline struct request *__elv_next_request(struct request_queue *q)
  71 {
  72         struct request *rq;
  73
  74         while (1) {
  75                 if (!list_empty(&q->queue_head)) {
  76                         rq = list_entry_rq(q->queue_head.next);
  77                         return rq;
  78                 }
  79
  80                 /*
  81                  * Flush request is running and flush request isn't queueable
  82                  * in the drive, we can hold the queue till flush request is
  83                  * finished. Even we don't do this, driver can't dispatch next
  84                  * requests and will requeue them. And this can improve
  85                  * throughput too. For example, we have request flush1, write1,
  86                  * flush 2. flush1 is dispatched, then queue is hold, write1
  87                  * isn't inserted to queue. After flush1 is finished, flush2
  88                  * will be dispatched. Since disk cache is already clean,
  89                  * flush2 will be finished very soon, so looks like flush2 is
  90                  * folded to flush1.
  91                  * Since the queue is hold, a flag is set to indicate the queue
  92                  * should be restarted later. Please see flush_end_io() for
  93                  * details.
  94                  */
  95                 if (q->flush_pending_idx != q->flush_running_idx &&
  96                                 !queue_flush_queueable(q)) {
  97                         q->flush_queue_delayed = 1;
  98                         return NULL;
  99                 }
 100                 if (unlikely(blk_queue_dead(q)) ||
 101                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
 102                         return NULL;
 103         }
 104 }
 105
 106 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 107 {
 108         struct elevator_queue *e = q->elevator;
 109
 110         if (e->type->ops.elevator_activate_req_fn)
 111                 e->type->ops.elevator_activate_req_fn(q, rq);
 112 }
 113
 114 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 115 {
 116         struct elevator_queue *e = q->elevator;
 117
 118         if (e->type->ops.elevator_deactivate_req_fn)
 119                 e->type->ops.elevator_deactivate_req_fn(q, rq);
 120 }
 121
 122 #ifdef CONFIG_FAIL_IO_TIMEOUT
 123 int blk_should_fake_timeout(struct request_queue *);
 124 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 125 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 126                                 const char *, size_t);
 127 #else
 128 static inline int blk_should_fake_timeout(struct request_queue *q)
 129 {
 130         return 0;
 131 }
 132 #endif
 133
 134 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 135                      struct bio *bio);
 136 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 137                       struct bio *bio);
 138 int attempt_back_merge(struct request_queue *q, struct request *rq);
 139 int attempt_front_merge(struct request_queue *q, struct request *rq);
 140 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 141                                 struct request *next);
 142 void blk_recalc_rq_segments(struct request *rq);
 143 void blk_rq_set_mixed_merge(struct request *rq);
 144 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 145 int blk_try_merge(struct request *rq, struct bio *bio);
 146
 147 void blk_queue_congestion_threshold(struct request_queue *q);
 148
 149 int blk_dev_init(void);
 150
 151
 152 /*
 153  * Return the threshold (number of used requests) at which the queue is
 154  * considered to be congested.  It include a little hysteresis to keep the
 155  * context switch rate down.
 156  */
 157 static inline int queue_congestion_on_threshold(struct request_queue *q)
 158 {
 159         return q->nr_congestion_on;
 160 }
 161
 162 /*
 163  * The threshold at which a queue is considered to be uncongested
 164  */
 165 static inline int queue_congestion_off_threshold(struct request_queue *q)
 166 {
 167         return q->nr_congestion_off;
 168 }
 169
 170 /*
 171  * Contribute to IO statistics IFF:
 172  *
 173  *      a) it's attached to a gendisk, and
 174  *      b) the queue had IO stats enabled when this request was started, and
 175  *      c) it's a file system request or a discard request
 176  */
 177 static inline int blk_do_io_stat(struct request *rq)
 178 {
 179         return rq->rq_disk &&
 180                (rq->cmd_flags & REQ_IO_STAT) &&
 181                (rq->cmd_type == REQ_TYPE_FS ||
 182                 (rq->cmd_flags & REQ_DISCARD));
 183 }
 184
 185 /*
 186  * Internal io_context interface
 187  */
 188 void get_io_context(struct io_context *ioc);
 189 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 190 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 191                              gfp_t gfp_mask);
 192 void ioc_clear_queue(struct request_queue *q);
 193
 194 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
 195
 196 /**
 197  * create_io_context - try to create task->io_context
 198  * @gfp_mask: allocation mask
 199  * @node: allocation node
 200  *
 201  * If %current->io_context is %NULL, allocate a new io_context and install
 202  * it.  Returns the current %current->io_context which may be %NULL if
 203  * allocation failed.
 204  *
 205  * Note that this function can't be called with IRQ disabled because
 206  * task_lock which protects %current->io_context is IRQ-unsafe.
 207  */
 208 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
 209 {
 210         WARN_ON_ONCE(irqs_disabled());
 211         if (unlikely(!current->io_context))
 212                 create_task_io_context(current, gfp_mask, node);
 213         return current->io_context;
 214 }
 215
 216 /*
 217  * Internal throttling interface
 218  */
 219 #ifdef CONFIG_BLK_DEV_THROTTLING
 220 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 221 extern void blk_throtl_drain(struct request_queue *q);
 222 extern int blk_throtl_init(struct request_queue *q);
 223 extern void blk_throtl_exit(struct request_queue *q);
 224 #else /* CONFIG_BLK_DEV_THROTTLING */
 225 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 226 {
 227         return false;
 228 }
 229 static inline void blk_throtl_drain(struct request_queue *q) { }
 230 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 231 static inline void blk_throtl_exit(struct request_queue *q) { }
 232 #endif /* CONFIG_BLK_DEV_THROTTLING */
 233
 234 #endif /* BLK_INTERNAL_H */