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
  54struct request *blk_do_flush(struct request_queue *q, struct request *rq);
  55
  56static inline struct request *__elv_next_request(struct request_queue *q)
  57{
  58        struct request *rq;
  59
  60        while (1) {
  61                while (!list_empty(&q->queue_head)) {
  62                        rq = list_entry_rq(q->queue_head.next);
  63                        if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) ||
  64                            rq == &q->flush_rq)
  65                                return rq;
  66                        rq = blk_do_flush(q, rq);
  67                        if (rq)
  68                                return rq;
  69                }
  70
  71                if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
  72                        return NULL;
  73        }
  74}
  75
  76static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
  77{
  78        struct elevator_queue *e = q->elevator;
  79
  80        if (e->ops->elevator_activate_req_fn)
  81                e->ops->elevator_activate_req_fn(q, rq);
  82}
  83
  84static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
  85{
  86        struct elevator_queue *e = q->elevator;
  87
  88        if (e->ops->elevator_deactivate_req_fn)
  89                e->ops->elevator_deactivate_req_fn(q, rq);
  90}
  91
  92#ifdef CONFIG_FAIL_IO_TIMEOUT
  93int blk_should_fake_timeout(struct request_queue *);
  94ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
  95ssize_t part_timeout_store(struct device *, struct device_attribute *,
  96                                const char *, size_t);
  97#else
  98static inline int blk_should_fake_timeout(struct request_queue *q)
  99{
 100        return 0;
 101}
 102#endif
 103
 104struct io_context *current_io_context(gfp_t gfp_flags, int node);
 105
 106int ll_back_merge_fn(struct request_queue *q, struct request *req,
 107                     struct bio *bio);
 108int ll_front_merge_fn(struct request_queue *q, struct request *req, 
 109                      struct bio *bio);
 110int attempt_back_merge(struct request_queue *q, struct request *rq);
 111int attempt_front_merge(struct request_queue *q, struct request *rq);
 112void blk_recalc_rq_segments(struct request *rq);
 113void blk_rq_set_mixed_merge(struct request *rq);
 114
 115void blk_queue_congestion_threshold(struct request_queue *q);
 116
 117int blk_dev_init(void);
 118
 119void elv_quiesce_start(struct request_queue *q);
 120void elv_quiesce_end(struct request_queue *q);
 121
 122
 123/*
 124 * Return the threshold (number of used requests) at which the queue is
 125 * considered to be congested.  It include a little hysteresis to keep the
 126 * context switch rate down.
 127 */
 128static inline int queue_congestion_on_threshold(struct request_queue *q)
 129{
 130        return q->nr_congestion_on;
 131}
 132
 133/*
 134 * The threshold at which a queue is considered to be uncongested
 135 */
 136static inline int queue_congestion_off_threshold(struct request_queue *q)
 137{
 138        return q->nr_congestion_off;
 139}
 140
 141static inline int blk_cpu_to_group(int cpu)
 142{
 143        int group = NR_CPUS;
 144#ifdef CONFIG_SCHED_MC
 145        const struct cpumask *mask = cpu_coregroup_mask(cpu);
 146        group = cpumask_first(mask);
 147#elif defined(CONFIG_SCHED_SMT)
 148        group = cpumask_first(topology_thread_cpumask(cpu));
 149#else
 150        return cpu;
 151#endif
 152        if (likely(group < NR_CPUS))
 153                return group;
 154        return cpu;
 155}
 156
 157/*
 158 * Contribute to IO statistics IFF:
 159 *
 160 *      a) it's attached to a gendisk, and
 161 *      b) the queue had IO stats enabled when this request was started, and
 162 *      c) it's a file system request or a discard request
 163 */
 164static inline int blk_do_io_stat(struct request *rq)
 165{
 166        return rq->rq_disk &&
 167               (rq->cmd_flags & REQ_IO_STAT) &&
 168               (rq->cmd_type == REQ_TYPE_FS ||
 169                (rq->cmd_flags & REQ_DISCARD));
 170}
 171
 172#endif
 173