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 struct blk_flush_queue {
  16         unsigned int            flush_queue_delayed:1;
  17         unsigned int            flush_pending_idx:1;
  18         unsigned int            flush_running_idx:1;
  19         unsigned long           flush_pending_since;
  20         struct list_head        flush_queue[2];
  21         struct list_head        flush_data_in_flight;
  22         struct request          *flush_rq;
  23         spinlock_t              mq_flush_lock;
  24 };
  25
  26 extern struct kmem_cache *blk_requestq_cachep;
  27 extern struct kmem_cache *request_cachep;
  28 extern struct kobj_type blk_queue_ktype;
  29 extern struct ida blk_queue_ida;
  30
  31 static inline struct blk_flush_queue *blk_get_flush_queue(
  32                 struct request_queue *q)
  33 {
  34         return q->fq;
  35 }
  36
  37 static inline void __blk_get_queue(struct request_queue *q)
  38 {
  39         kobject_get(&q->kobj);
  40 }
  41
  42 struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q);
  43 void blk_free_flush_queue(struct blk_flush_queue *fq);
  44
  45 int blk_init_rl(struct request_list *rl, struct request_queue *q,
  46                 gfp_t gfp_mask);
  47 void blk_exit_rl(struct request_list *rl);
  48 void init_request_from_bio(struct request *req, struct bio *bio);
  49 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  50                         struct bio *bio);
  51 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  52                       struct bio *bio);
  53 void blk_queue_bypass_start(struct request_queue *q);
  54 void blk_queue_bypass_end(struct request_queue *q);
  55 void blk_dequeue_request(struct request *rq);
  56 void __blk_queue_free_tags(struct request_queue *q);
  57 bool __blk_end_bidi_request(struct request *rq, int error,
  58                             unsigned int nr_bytes, unsigned int bidi_bytes);
  59
  60 void blk_rq_timed_out_timer(unsigned long data);
  61 unsigned long blk_rq_timeout(unsigned long timeout);
  62 void blk_add_timer(struct request *req);
  63 void blk_delete_timer(struct request *);
  64
  65
  66 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
  67                              struct bio *bio);
  68 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
  69                             struct bio *bio);
  70 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
  71                             unsigned int *request_count);
  72
  73 void blk_account_io_start(struct request *req, bool new_io);
  74 void blk_account_io_completion(struct request *req, unsigned int bytes);
  75 void blk_account_io_done(struct request *req);
  76
  77 /*
  78  * Internal atomic flags for request handling
  79  */
  80 enum rq_atomic_flags {
  81         REQ_ATOM_COMPLETE = 0,
  82         REQ_ATOM_STARTED,
  83 };
  84
  85 /*
  86  * EH timer and IO completion will both attempt to 'grab' the request, make
  87  * sure that only one of them succeeds
  88  */
  89 static inline int blk_mark_rq_complete(struct request *rq)
  90 {
  91         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  92 }
  93
  94 static inline void blk_clear_rq_complete(struct request *rq)
  95 {
  96         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  97 }
  98
  99 /*
 100  * Internal elevator interface
 101  */
 102 #define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
 103
 104 void blk_insert_flush(struct request *rq);
 105
 106 static inline struct request *__elv_next_request(struct request_queue *q)
 107 {
 108         struct request *rq;
 109         struct blk_flush_queue *fq = blk_get_flush_queue(q);
 110
 111         while (1) {
 112                 if (!list_empty(&q->queue_head)) {
 113                         rq = list_entry_rq(q->queue_head.next);
 114                         return rq;
 115                 }
 116
 117                 /*
 118                  * Flush request is running and flush request isn't queueable
 119                  * in the drive, we can hold the queue till flush request is
 120                  * finished. Even we don't do this, driver can't dispatch next
 121                  * requests and will requeue them. And this can improve
 122                  * throughput too. For example, we have request flush1, write1,
 123                  * flush 2. flush1 is dispatched, then queue is hold, write1
 124                  * isn't inserted to queue. After flush1 is finished, flush2
 125                  * will be dispatched. Since disk cache is already clean,
 126                  * flush2 will be finished very soon, so looks like flush2 is
 127                  * folded to flush1.
 128                  * Since the queue is hold, a flag is set to indicate the queue
 129                  * should be restarted later. Please see flush_end_io() for
 130                  * details.
 131                  */
 132                 if (fq->flush_pending_idx != fq->flush_running_idx &&
 133                                 !queue_flush_queueable(q)) {
 134                         fq->flush_queue_delayed = 1;
 135                         return NULL;
 136                 }
 137                 if (unlikely(blk_queue_bypass(q)) ||
 138                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
 139                         return NULL;
 140         }
 141 }
 142
 143 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 144 {
 145         struct elevator_queue *e = q->elevator;
 146
 147         if (e->type->ops.elevator_activate_req_fn)
 148                 e->type->ops.elevator_activate_req_fn(q, rq);
 149 }
 150
 151 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 152 {
 153         struct elevator_queue *e = q->elevator;
 154
 155         if (e->type->ops.elevator_deactivate_req_fn)
 156                 e->type->ops.elevator_deactivate_req_fn(q, rq);
 157 }
 158
 159 #ifdef CONFIG_FAIL_IO_TIMEOUT
 160 int blk_should_fake_timeout(struct request_queue *);
 161 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 162 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 163                                 const char *, size_t);
 164 #else
 165 static inline int blk_should_fake_timeout(struct request_queue *q)
 166 {
 167         return 0;
 168 }
 169 #endif
 170
 171 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 172                      struct bio *bio);
 173 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 174                       struct bio *bio);
 175 int attempt_back_merge(struct request_queue *q, struct request *rq);
 176 int attempt_front_merge(struct request_queue *q, struct request *rq);
 177 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 178                                 struct request *next);
 179 void blk_recalc_rq_segments(struct request *rq);
 180 void blk_rq_set_mixed_merge(struct request *rq);
 181 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 182 int blk_try_merge(struct request *rq, struct bio *bio);
 183
 184 void blk_queue_congestion_threshold(struct request_queue *q);
 185
 186 void __blk_run_queue_uncond(struct request_queue *q);
 187
 188 int blk_dev_init(void);
 189
 190
 191 /*
 192  * Return the threshold (number of used requests) at which the queue is
 193  * considered to be congested.  It include a little hysteresis to keep the
 194  * context switch rate down.
 195  */
 196 static inline int queue_congestion_on_threshold(struct request_queue *q)
 197 {
 198         return q->nr_congestion_on;
 199 }
 200
 201 /*
 202  * The threshold at which a queue is considered to be uncongested
 203  */
 204 static inline int queue_congestion_off_threshold(struct request_queue *q)
 205 {
 206         return q->nr_congestion_off;
 207 }
 208
 209 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
 210
 211 /*
 212  * Contribute to IO statistics IFF:
 213  *
 214  *      a) it's attached to a gendisk, and
 215  *      b) the queue had IO stats enabled when this request was started, and
 216  *      c) it's a file system request
 217  */
 218 static inline int blk_do_io_stat(struct request *rq)
 219 {
 220         return rq->rq_disk &&
 221                (rq->cmd_flags & REQ_IO_STAT) &&
 222                 (rq->cmd_type == REQ_TYPE_FS);
 223 }
 224
 225 /*
 226  * Internal io_context interface
 227  */
 228 void get_io_context(struct io_context *ioc);
 229 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 230 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 231                              gfp_t gfp_mask);
 232 void ioc_clear_queue(struct request_queue *q);
 233
 234 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
 235
 236 /**
 237  * create_io_context - try to create task->io_context
 238  * @gfp_mask: allocation mask
 239  * @node: allocation node
 240  *
 241  * If %current->io_context is %NULL, allocate a new io_context and install
 242  * it.  Returns the current %current->io_context which may be %NULL if
 243  * allocation failed.
 244  *
 245  * Note that this function can't be called with IRQ disabled because
 246  * task_lock which protects %current->io_context is IRQ-unsafe.
 247  */
 248 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
 249 {
 250         WARN_ON_ONCE(irqs_disabled());
 251         if (unlikely(!current->io_context))
 252                 create_task_io_context(current, gfp_mask, node);
 253         return current->io_context;
 254 }
 255
 256 /*
 257  * Internal throttling interface
 258  */
 259 #ifdef CONFIG_BLK_DEV_THROTTLING
 260 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 261 extern void blk_throtl_drain(struct request_queue *q);
 262 extern int blk_throtl_init(struct request_queue *q);
 263 extern void blk_throtl_exit(struct request_queue *q);
 264 #else /* CONFIG_BLK_DEV_THROTTLING */
 265 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 266 {
 267         return false;
 268 }
 269 static inline void blk_throtl_drain(struct request_queue *q) { }
 270 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 271 static inline void blk_throtl_exit(struct request_queue *q) { }
 272 #endif /* CONFIG_BLK_DEV_THROTTLING */
 273
 274 #endif /* BLK_INTERNAL_H */