LXR linux/block/blk.h

   1#ifndef BLK_INTERNAL_H
   2#define BLK_INTERNAL_H
   3
   4/* Amount of time in which a process may batch requests */
   5#define BLK_BATCH_TIME  (HZ/50UL)
   6
   7/* Number of requests a "batching" process may submit */
   8#define BLK_BATCH_REQ   32
   9
  10extern struct kmem_cache *blk_requestq_cachep;
  11extern struct kobj_type blk_queue_ktype;
  12
  13void init_request_from_bio(struct request *req, struct bio *bio);
  14void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  15                        struct bio *bio);
  16int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  17                      struct bio *bio);
  18void blk_dequeue_request(struct request *rq);
  19void __blk_queue_free_tags(struct request_queue *q);
  20
  21void blk_unplug_work(struct work_struct *work);
  22void blk_unplug_timeout(unsigned long data);
  23void blk_rq_timed_out_timer(unsigned long data);
  24void blk_delete_timer(struct request *);
  25void blk_add_timer(struct request *);
  26void __generic_unplug_device(struct request_queue *);
  27
  28/*
  29 * Internal atomic flags for request handling
  30 */
  31enum rq_atomic_flags {
  32        REQ_ATOM_COMPLETE = 0,
  33};
  34
  35/*
  36 * EH timer and IO completion will both attempt to 'grab' the request, make
  37 * sure that only one of them suceeds
  38 */
  39static inline int blk_mark_rq_complete(struct request *rq)
  40{
  41        return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  42}
  43
  44static inline void blk_clear_rq_complete(struct request *rq)
  45{
  46        clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  47}
  48
  49/*
  50 * Internal elevator interface
  51 */
  52#define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
  53
  54static inline struct request *__elv_next_request(struct request_queue *q)
  55{
  56        struct request *rq;
  57
  58        while (1) {
  59                while (!list_empty(&q->queue_head)) {
  60                        rq = list_entry_rq(q->queue_head.next);
  61                        if (blk_do_ordered(q, &rq))
  62                                return rq;
  63                }
  64
  65                if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
  66                        return NULL;
  67        }
  68}
  69
  70static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  71{
  72        struct elevator_queue *e = q->elevator;
  73
  74        if (e->ops->elevator_activate_req_fn)
  75                e->ops->elevator_activate_req_fn(q, rq);
  76}
  77
  78static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
  79{
  80        struct elevator_queue *e = q->elevator;
  81
  82        if (e->ops->elevator_deactivate_req_fn)
  83                e->ops->elevator_deactivate_req_fn(q, rq);
  84}
  85
  86#ifdef CONFIG_FAIL_IO_TIMEOUT
  87int blk_should_fake_timeout(struct request_queue *);
  88ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
  89ssize_t part_timeout_store(struct device *, struct device_attribute *,
  90                                const char *, size_t);
  91#else
  92static inline int blk_should_fake_timeout(struct request_queue *q)
  93{
  94        return 0;
  95}
  96#endif
  97
  98struct io_context *current_io_context(gfp_t gfp_flags, int node);
  99
 100int ll_back_merge_fn(struct request_queue *q, struct request *req,
 101                     struct bio *bio);
 102int ll_front_merge_fn(struct request_queue *q, struct request *req, 
 103                      struct bio *bio);
 104int attempt_back_merge(struct request_queue *q, struct request *rq);
 105int attempt_front_merge(struct request_queue *q, struct request *rq);
 106void blk_recalc_rq_segments(struct request *rq);
 107void blk_rq_set_mixed_merge(struct request *rq);
 108
 109void blk_queue_congestion_threshold(struct request_queue *q);
 110
 111int blk_dev_init(void);
 112
 113void elv_quiesce_start(struct request_queue *q);
 114void elv_quiesce_end(struct request_queue *q);
 115
 116
 117/*
 118 * Return the threshold (number of used requests) at which the queue is
 119 * considered to be congested.  It include a little hysteresis to keep the
 120 * context switch rate down.
 121 */
 122static inline int queue_congestion_on_threshold(struct request_queue *q)
 123{
 124        return q->nr_congestion_on;
 125}
 126
 127/*
 128 * The threshold at which a queue is considered to be uncongested
 129 */
 130static inline int queue_congestion_off_threshold(struct request_queue *q)
 131{
 132        return q->nr_congestion_off;
 133}
 134
 135#if defined(CONFIG_BLK_DEV_INTEGRITY)
 136
 137#define rq_for_each_integrity_segment(bvl, _rq, _iter)          \
 138        __rq_for_each_bio(_iter.bio, _rq)                       \
 139                bip_for_each_vec(bvl, _iter.bio->bi_integrity, _iter.i)
 140
 141#endif /* BLK_DEV_INTEGRITY */
 142
 143static inline int blk_cpu_to_group(int cpu)
 144{
 145#ifdef CONFIG_SCHED_MC
 146        const struct cpumask *mask = cpu_coregroup_mask(cpu);
 147        return cpumask_first(mask);
 148#elif defined(CONFIG_SCHED_SMT)
 149        return cpumask_first(topology_thread_cpumask(cpu));
 150#else
 151        return cpu;
 152#endif
 153}
 154
 155/*
 156 * Contribute to IO statistics IFF:
 157 *
 158 *      a) it's attached to a gendisk, and
 159 *      b) the queue had IO stats enabled when this request was started, and
 160 *      c) it's a file system request or a discard request
 161 */
 162static inline int blk_do_io_stat(struct request *rq)
 163{
 164        return rq->rq_disk && blk_rq_io_stat(rq) &&
 165               (blk_fs_request(rq) || blk_discard_rq(rq));
 166}
 167
 168#endif
 169