linux/block/blk.h
<<
>>
Prefs
   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
  12extern struct kmem_cache *blk_requestq_cachep;
  13extern struct kobj_type blk_queue_ktype;
  14extern struct ida blk_queue_ida;
  15
  16static inline void __blk_get_queue(struct request_queue *q)
  17{
  18        kobject_get(&q->kobj);
  19}
  20
  21void init_request_from_bio(struct request *req, struct bio *bio);
  22void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  23                        struct bio *bio);
  24int blk_rq_append_bio(struct request_queue *q, struct request *rq,
  25                      struct bio *bio);
  26void blk_queue_bypass_start(struct request_queue *q);
  27void blk_queue_bypass_end(struct request_queue *q);
  28void blk_dequeue_request(struct request *rq);
  29void __blk_queue_free_tags(struct request_queue *q);
  30bool __blk_end_bidi_request(struct request *rq, int error,
  31                            unsigned int nr_bytes, unsigned int bidi_bytes);
  32
  33void blk_rq_timed_out_timer(unsigned long data);
  34void blk_delete_timer(struct request *);
  35void blk_add_timer(struct request *);
  36void __generic_unplug_device(struct request_queue *);
  37
  38/*
  39 * Internal atomic flags for request handling
  40 */
  41enum 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 */
  49static inline int blk_mark_rq_complete(struct request *rq)
  50{
  51        return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
  52}
  53
  54static 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
  64void blk_insert_flush(struct request *rq);
  65void blk_abort_flushes(struct request_queue *q);
  66
  67static 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
 103static 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
 111static 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
 120int blk_should_fake_timeout(struct request_queue *);
 121ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 122ssize_t part_timeout_store(struct device *, struct device_attribute *,
 123                                const char *, size_t);
 124#else
 125static inline int blk_should_fake_timeout(struct request_queue *q)
 126{
 127        return 0;
 128}
 129#endif
 130
 131int ll_back_merge_fn(struct request_queue *q, struct request *req,
 132                     struct bio *bio);
 133int ll_front_merge_fn(struct request_queue *q, struct request *req, 
 134                      struct bio *bio);
 135int attempt_back_merge(struct request_queue *q, struct request *rq);
 136int attempt_front_merge(struct request_queue *q, struct request *rq);
 137int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 138                                struct request *next);
 139void blk_recalc_rq_segments(struct request *rq);
 140void blk_rq_set_mixed_merge(struct request *rq);
 141bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 142int blk_try_merge(struct request *rq, struct bio *bio);
 143
 144void blk_queue_congestion_threshold(struct request_queue *q);
 145
 146int 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 */
 154static 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 */
 162static 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 */
 174static 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 */
 185void get_io_context(struct io_context *ioc);
 186struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 187struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 188                             gfp_t gfp_mask);
 189void ioc_clear_queue(struct request_queue *q);
 190
 191int 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 */
 205static 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
 217extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 218extern void blk_throtl_drain(struct request_queue *q);
 219extern int blk_throtl_init(struct request_queue *q);
 220extern void blk_throtl_exit(struct request_queue *q);
 221#else /* CONFIG_BLK_DEV_THROTTLING */
 222static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 223{
 224        return false;
 225}
 226static inline void blk_throtl_drain(struct request_queue *q) { }
 227static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 228static inline void blk_throtl_exit(struct request_queue *q) { }
 229#endif /* CONFIG_BLK_DEV_THROTTLING */
 230
 231#endif /* BLK_INTERNAL_H */
 232
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.