Root/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

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