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
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

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