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