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 /* Max future timer expiry for timeouts */
  13 #define BLK_MAX_TIMEOUT         (5 * HZ)
  14
  15 extern struct kmem_cache *blk_requestq_cachep;
  16 extern struct kmem_cache *request_cachep;
  17 extern struct kobj_type blk_queue_ktype;
  18 extern struct ida blk_queue_ida;
  19
  20 static inline void __blk_get_queue(struct request_queue *q)
  21 {
  22         kobject_get(&q->kobj);
  23 }
  24
  25 int blk_init_rl(struct request_list *rl, struct request_queue *q,
  26                 gfp_t gfp_mask);
  27 void blk_exit_rl(struct request_list *rl);
  28 void init_request_from_bio(struct request *req, struct bio *bio);
  29 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  30                         struct bio *bio);
  31 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  32                       struct bio *bio);
  33 void blk_queue_bypass_start(struct request_queue *q);
  34 void blk_queue_bypass_end(struct request_queue *q);
  35 void blk_dequeue_request(struct request *rq);
  36 void __blk_queue_free_tags(struct request_queue *q);
  37 bool __blk_end_bidi_request(struct request *rq, int error,
  38                             unsigned int nr_bytes, unsigned int bidi_bytes);
  39
  40 void blk_rq_timed_out_timer(unsigned long data);
  41 void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
  42                           unsigned int *next_set);
  43 unsigned long blk_rq_timeout(unsigned long timeout);
  44 void blk_add_timer(struct request *req);
  45 void blk_delete_timer(struct request *);
  46
  47
  48 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
  49                              struct bio *bio);
  50 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
  51                             struct bio *bio);
  52 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
  53                             unsigned int *request_count);
  54
  55 void blk_account_io_start(struct request *req, bool new_io);
  56 void blk_account_io_completion(struct request *req, unsigned int bytes);
  57 void blk_account_io_done(struct request *req);
  58
  59 /*
  60  * Internal atomic flags for request handling
  61  */
  62 enum rq_atomic_flags {
  63         REQ_ATOM_COMPLETE = 0,
  64         REQ_ATOM_STARTED,
  65 };
  66
  67 /*
  68  * EH timer and IO completion will both attempt to 'grab' the request, make
  69  * sure that only one of them succeeds
  70  */
  71 static inline int blk_mark_rq_complete(struct request *rq)
  72 {
  73         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  74 }
  75
  76 static inline void blk_clear_rq_complete(struct request *rq)
  77 {
  78         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  79 }
  80
  81 /*
  82  * Internal elevator interface
  83  */
  84 #define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
  85
  86 void blk_insert_flush(struct request *rq);
  87
  88 static inline struct request *__elv_next_request(struct request_queue *q)
  89 {
  90         struct request *rq;
  91
  92         while (1) {
  93                 if (!list_empty(&q->queue_head)) {
  94                         rq = list_entry_rq(q->queue_head.next);
  95                         return rq;
  96                 }
  97
  98                 /*
  99                  * Flush request is running and flush request isn't queueable
 100                  * in the drive, we can hold the queue till flush request is
 101                  * finished. Even we don't do this, driver can't dispatch next
 102                  * requests and will requeue them. And this can improve
 103                  * throughput too. For example, we have request flush1, write1,
 104                  * flush 2. flush1 is dispatched, then queue is hold, write1
 105                  * isn't inserted to queue. After flush1 is finished, flush2
 106                  * will be dispatched. Since disk cache is already clean,
 107                  * flush2 will be finished very soon, so looks like flush2 is
 108                  * folded to flush1.
 109                  * Since the queue is hold, a flag is set to indicate the queue
 110                  * should be restarted later. Please see flush_end_io() for
 111                  * details.
 112                  */
 113                 if (q->flush_pending_idx != q->flush_running_idx &&
 114                                 !queue_flush_queueable(q)) {
 115                         q->flush_queue_delayed = 1;
 116                         return NULL;
 117                 }
 118                 if (unlikely(blk_queue_bypass(q)) ||
 119                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
 120                         return NULL;
 121         }
 122 }
 123
 124 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 125 {
 126         struct elevator_queue *e = q->elevator;
 127
 128         if (e->type->ops.elevator_activate_req_fn)
 129                 e->type->ops.elevator_activate_req_fn(q, rq);
 130 }
 131
 132 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 133 {
 134         struct elevator_queue *e = q->elevator;
 135
 136         if (e->type->ops.elevator_deactivate_req_fn)
 137                 e->type->ops.elevator_deactivate_req_fn(q, rq);
 138 }
 139
 140 #ifdef CONFIG_FAIL_IO_TIMEOUT
 141 int blk_should_fake_timeout(struct request_queue *);
 142 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 143 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 144                                 const char *, size_t);
 145 #else
 146 static inline int blk_should_fake_timeout(struct request_queue *q)
 147 {
 148         return 0;
 149 }
 150 #endif
 151
 152 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 153                      struct bio *bio);
 154 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 155                       struct bio *bio);
 156 int attempt_back_merge(struct request_queue *q, struct request *rq);
 157 int attempt_front_merge(struct request_queue *q, struct request *rq);
 158 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 159                                 struct request *next);
 160 void blk_recalc_rq_segments(struct request *rq);
 161 void blk_rq_set_mixed_merge(struct request *rq);
 162 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 163 int blk_try_merge(struct request *rq, struct bio *bio);
 164
 165 void blk_queue_congestion_threshold(struct request_queue *q);
 166
 167 void __blk_run_queue_uncond(struct request_queue *q);
 168
 169 int blk_dev_init(void);
 170
 171
 172 /*
 173  * Return the threshold (number of used requests) at which the queue is
 174  * considered to be congested.  It include a little hysteresis to keep the
 175  * context switch rate down.
 176  */
 177 static inline int queue_congestion_on_threshold(struct request_queue *q)
 178 {
 179         return q->nr_congestion_on;
 180 }
 181
 182 /*
 183  * The threshold at which a queue is considered to be uncongested
 184  */
 185 static inline int queue_congestion_off_threshold(struct request_queue *q)
 186 {
 187         return q->nr_congestion_off;
 188 }
 189
 190 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
 191
 192 /*
 193  * Contribute to IO statistics IFF:
 194  *
 195  *      a) it's attached to a gendisk, and
 196  *      b) the queue had IO stats enabled when this request was started, and
 197  *      c) it's a file system request
 198  */
 199 static inline int blk_do_io_stat(struct request *rq)
 200 {
 201         return rq->rq_disk &&
 202                (rq->cmd_flags & REQ_IO_STAT) &&
 203                 (rq->cmd_type == REQ_TYPE_FS);
 204 }
 205
 206 /*
 207  * Internal io_context interface
 208  */
 209 void get_io_context(struct io_context *ioc);
 210 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 211 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 212                              gfp_t gfp_mask);
 213 void ioc_clear_queue(struct request_queue *q);
 214
 215 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
 216
 217 /**
 218  * create_io_context - try to create task->io_context
 219  * @gfp_mask: allocation mask
 220  * @node: allocation node
 221  *
 222  * If %current->io_context is %NULL, allocate a new io_context and install
 223  * it.  Returns the current %current->io_context which may be %NULL if
 224  * allocation failed.
 225  *
 226  * Note that this function can't be called with IRQ disabled because
 227  * task_lock which protects %current->io_context is IRQ-unsafe.
 228  */
 229 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
 230 {
 231         WARN_ON_ONCE(irqs_disabled());
 232         if (unlikely(!current->io_context))
 233                 create_task_io_context(current, gfp_mask, node);
 234         return current->io_context;
 235 }
 236
 237 /*
 238  * Internal throttling interface
 239  */
 240 #ifdef CONFIG_BLK_DEV_THROTTLING
 241 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 242 extern void blk_throtl_drain(struct request_queue *q);
 243 extern int blk_throtl_init(struct request_queue *q);
 244 extern void blk_throtl_exit(struct request_queue *q);
 245 #else /* CONFIG_BLK_DEV_THROTTLING */
 246 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 247 {
 248         return false;
 249 }
 250 static inline void blk_throtl_drain(struct request_queue *q) { }
 251 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 252 static inline void blk_throtl_exit(struct request_queue *q) { }
 253 #endif /* CONFIG_BLK_DEV_THROTTLING */
 254
 255 #endif /* BLK_INTERNAL_H */