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