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 void init_request_from_bio(struct request *req, struct bio *bio);
  22 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  23                         struct bio *bio);
  24 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  25                       struct bio *bio);
  26 void blk_drain_queue(struct request_queue *q, bool drain_all);
  27 void blk_dequeue_request(struct request *rq);
  28 void __blk_queue_free_tags(struct request_queue *q);
  29 bool __blk_end_bidi_request(struct request *rq, int error,
  30                             unsigned int nr_bytes, unsigned int bidi_bytes);
  31
  32 void blk_rq_timed_out_timer(unsigned long data);
  33 void blk_delete_timer(struct request *);
  34 void blk_add_timer(struct request *);
  35 void __generic_unplug_device(struct request_queue *);
  36
  37 /*
  38  * Internal atomic flags for request handling
  39  */
  40 enum rq_atomic_flags {
  41         REQ_ATOM_COMPLETE = 0,
  42 };
  43
  44 /*
  45  * EH timer and IO completion will both attempt to 'grab' the request, make
  46  * sure that only one of them succeeds
  47  */
  48 static inline int blk_mark_rq_complete(struct request *rq)
  49 {
  50         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  51 }
  52
  53 static inline void blk_clear_rq_complete(struct request *rq)
  54 {
  55         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  56 }
  57
  58 /*
  59  * Internal elevator interface
  60  */
  61 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  62
  63 void blk_insert_flush(struct request *rq);
  64 void blk_abort_flushes(struct request_queue *q);
  65
  66 static inline struct request *__elv_next_request(struct request_queue *q)
  67 {
  68         struct request *rq;
  69
  70         while (1) {
  71                 if (!list_empty(&q->queue_head)) {
  72                         rq = list_entry_rq(q->queue_head.next);
  73                         return rq;
  74                 }
  75
  76                 /*
  77                  * Flush request is running and flush request isn't queueable
  78                  * in the drive, we can hold the queue till flush request is
  79                  * finished. Even we don't do this, driver can't dispatch next
  80                  * requests and will requeue them. And this can improve
  81                  * throughput too. For example, we have request flush1, write1,
  82                  * flush 2. flush1 is dispatched, then queue is hold, write1
  83                  * isn't inserted to queue. After flush1 is finished, flush2
  84                  * will be dispatched. Since disk cache is already clean,
  85                  * flush2 will be finished very soon, so looks like flush2 is
  86                  * folded to flush1.
  87                  * Since the queue is hold, a flag is set to indicate the queue
  88                  * should be restarted later. Please see flush_end_io() for
  89                  * details.
  90                  */
  91                 if (q->flush_pending_idx != q->flush_running_idx &&
  92                                 !queue_flush_queueable(q)) {
  93                         q->flush_queue_delayed = 1;
  94                         return NULL;
  95                 }
  96                 if (unlikely(blk_queue_dead(q)) ||
  97                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
  98                         return NULL;
  99         }
 100 }
 101
 102 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 103 {
 104         struct elevator_queue *e = q->elevator;
 105
 106         if (e->type->ops.elevator_activate_req_fn)
 107                 e->type->ops.elevator_activate_req_fn(q, rq);
 108 }
 109
 110 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 111 {
 112         struct elevator_queue *e = q->elevator;
 113
 114         if (e->type->ops.elevator_deactivate_req_fn)
 115                 e->type->ops.elevator_deactivate_req_fn(q, rq);
 116 }
 117
 118 #ifdef CONFIG_FAIL_IO_TIMEOUT
 119 int blk_should_fake_timeout(struct request_queue *);
 120 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 121 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 122                                 const char *, size_t);
 123 #else
 124 static inline int blk_should_fake_timeout(struct request_queue *q)
 125 {
 126         return 0;
 127 }
 128 #endif
 129
 130 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 131                      struct bio *bio);
 132 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 133                       struct bio *bio);
 134 int attempt_back_merge(struct request_queue *q, struct request *rq);
 135 int attempt_front_merge(struct request_queue *q, struct request *rq);
 136 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 137                                 struct request *next);
 138 void blk_recalc_rq_segments(struct request *rq);
 139 void blk_rq_set_mixed_merge(struct request *rq);
 140 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 141 int blk_try_merge(struct request *rq, struct bio *bio);
 142
 143 void blk_queue_congestion_threshold(struct request_queue *q);
 144
 145 int blk_dev_init(void);
 146
 147 void elv_quiesce_start(struct request_queue *q);
 148 void elv_quiesce_end(struct request_queue *q);
 149
 150
 151 /*
 152  * Return the threshold (number of used requests) at which the queue is
 153  * considered to be congested.  It include a little hysteresis to keep the
 154  * context switch rate down.
 155  */
 156 static inline int queue_congestion_on_threshold(struct request_queue *q)
 157 {
 158         return q->nr_congestion_on;
 159 }
 160
 161 /*
 162  * The threshold at which a queue is considered to be uncongested
 163  */
 164 static inline int queue_congestion_off_threshold(struct request_queue *q)
 165 {
 166         return q->nr_congestion_off;
 167 }
 168
 169 /*
 170  * Contribute to IO statistics IFF:
 171  *
 172  *      a) it's attached to a gendisk, and
 173  *      b) the queue had IO stats enabled when this request was started, and
 174  *      c) it's a file system request or a discard request
 175  */
 176 static inline int blk_do_io_stat(struct request *rq)
 177 {
 178         return rq->rq_disk &&
 179                (rq->cmd_flags & REQ_IO_STAT) &&
 180                (rq->cmd_type == REQ_TYPE_FS ||
 181                 (rq->cmd_flags & REQ_DISCARD));
 182 }
 183
 184 /*
 185  * Internal io_context interface
 186  */
 187 void get_io_context(struct io_context *ioc);
 188 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 189 struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask);
 190 void ioc_clear_queue(struct request_queue *q);
 191
 192 void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_mask,
 193                                 int node);
 194
 195 /**
 196  * create_io_context - try to create task->io_context
 197  * @task: target task
 198  * @gfp_mask: allocation mask
 199  * @node: allocation node
 200  *
 201  * If @task->io_context is %NULL, allocate a new io_context and install it.
 202  * Returns the current @task->io_context which may be %NULL if allocation
 203  * failed.
 204  *
 205  * Note that this function can't be called with IRQ disabled because
 206  * task_lock which protects @task->io_context is IRQ-unsafe.
 207  */
 208 static inline struct io_context *create_io_context(struct task_struct *task,
 209                                                    gfp_t gfp_mask, int node)
 210 {
 211         WARN_ON_ONCE(irqs_disabled());
 212         if (unlikely(!task->io_context))
 213                 create_io_context_slowpath(task, gfp_mask, node);
 214         return task->io_context;
 215 }
 216
 217 /*
 218  * Internal throttling interface
 219  */
 220 #ifdef CONFIG_BLK_DEV_THROTTLING
 221 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 222 extern void blk_throtl_drain(struct request_queue *q);
 223 extern int blk_throtl_init(struct request_queue *q);
 224 extern void blk_throtl_exit(struct request_queue *q);
 225 extern void blk_throtl_release(struct request_queue *q);
 226 #else /* CONFIG_BLK_DEV_THROTTLING */
 227 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 228 {
 229         return false;
 230 }
 231 static inline void blk_throtl_drain(struct request_queue *q) { }
 232 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 233 static inline void blk_throtl_exit(struct request_queue *q) { }
 234 static inline void blk_throtl_release(struct request_queue *q) { }
 235 #endif /* CONFIG_BLK_DEV_THROTTLING */
 236
 237 #endif /* BLK_INTERNAL_H */