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
  40 /*
  41  * Internal atomic flags for request handling
  42  */
  43 enum rq_atomic_flags {
  44         REQ_ATOM_COMPLETE = 0,
  45 };
  46
  47 /*
  48  * EH timer and IO completion will both attempt to 'grab' the request, make
  49  * sure that only one of them succeeds
  50  */
  51 static inline int blk_mark_rq_complete(struct request *rq)
  52 {
  53         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  54 }
  55
  56 static inline void blk_clear_rq_complete(struct request *rq)
  57 {
  58         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  59 }
  60
  61 /*
  62  * Internal elevator interface
  63  */
  64 #define ELV_ON_HASH(rq) hash_hashed(&(rq)->hash)
  65
  66 void blk_insert_flush(struct request *rq);
  67 void blk_abort_flushes(struct request_queue *q);
  68
  69 static inline struct request *__elv_next_request(struct request_queue *q)
  70 {
  71         struct request *rq;
  72
  73         while (1) {
  74                 if (!list_empty(&q->queue_head)) {
  75                         rq = list_entry_rq(q->queue_head.next);
  76                         return rq;
  77                 }
  78
  79                 /*
  80                  * Flush request is running and flush request isn't queueable
  81                  * in the drive, we can hold the queue till flush request is
  82                  * finished. Even we don't do this, driver can't dispatch next
  83                  * requests and will requeue them. And this can improve
  84                  * throughput too. For example, we have request flush1, write1,
  85                  * flush 2. flush1 is dispatched, then queue is hold, write1
  86                  * isn't inserted to queue. After flush1 is finished, flush2
  87                  * will be dispatched. Since disk cache is already clean,
  88                  * flush2 will be finished very soon, so looks like flush2 is
  89                  * folded to flush1.
  90                  * Since the queue is hold, a flag is set to indicate the queue
  91                  * should be restarted later. Please see flush_end_io() for
  92                  * details.
  93                  */
  94                 if (q->flush_pending_idx != q->flush_running_idx &&
  95                                 !queue_flush_queueable(q)) {
  96                         q->flush_queue_delayed = 1;
  97                         return NULL;
  98                 }
  99                 if (unlikely(blk_queue_dying(q)) ||
 100                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
 101                         return NULL;
 102         }
 103 }
 104
 105 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 106 {
 107         struct elevator_queue *e = q->elevator;
 108
 109         if (e->type->ops.elevator_activate_req_fn)
 110                 e->type->ops.elevator_activate_req_fn(q, rq);
 111 }
 112
 113 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 114 {
 115         struct elevator_queue *e = q->elevator;
 116
 117         if (e->type->ops.elevator_deactivate_req_fn)
 118                 e->type->ops.elevator_deactivate_req_fn(q, rq);
 119 }
 120
 121 #ifdef CONFIG_FAIL_IO_TIMEOUT
 122 int blk_should_fake_timeout(struct request_queue *);
 123 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 124 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 125                                 const char *, size_t);
 126 #else
 127 static inline int blk_should_fake_timeout(struct request_queue *q)
 128 {
 129         return 0;
 130 }
 131 #endif
 132
 133 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 134                      struct bio *bio);
 135 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 136                       struct bio *bio);
 137 int attempt_back_merge(struct request_queue *q, struct request *rq);
 138 int attempt_front_merge(struct request_queue *q, struct request *rq);
 139 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 140                                 struct request *next);
 141 void blk_recalc_rq_segments(struct request *rq);
 142 void blk_rq_set_mixed_merge(struct request *rq);
 143 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 144 int blk_try_merge(struct request *rq, struct bio *bio);
 145
 146 void blk_queue_congestion_threshold(struct request_queue *q);
 147
 148 void __blk_run_queue_uncond(struct request_queue *q);
 149
 150 int blk_dev_init(void);
 151
 152
 153 /*
 154  * Return the threshold (number of used requests) at which the queue is
 155  * considered to be congested.  It include a little hysteresis to keep the
 156  * context switch rate down.
 157  */
 158 static inline int queue_congestion_on_threshold(struct request_queue *q)
 159 {
 160         return q->nr_congestion_on;
 161 }
 162
 163 /*
 164  * The threshold at which a queue is considered to be uncongested
 165  */
 166 static inline int queue_congestion_off_threshold(struct request_queue *q)
 167 {
 168         return q->nr_congestion_off;
 169 }
 170
 171 /*
 172  * Contribute to IO statistics IFF:
 173  *
 174  *      a) it's attached to a gendisk, and
 175  *      b) the queue had IO stats enabled when this request was started, and
 176  *      c) it's a file system request
 177  */
 178 static inline int blk_do_io_stat(struct request *rq)
 179 {
 180         return rq->rq_disk &&
 181                (rq->cmd_flags & REQ_IO_STAT) &&
 182                 (rq->cmd_type == REQ_TYPE_FS);
 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 */