4 /* Amount of time in which a process may batch requests */
5 #define BLK_BATCH_TIME (HZ/50UL)
7 /* Number of requests a "batching" process may submit */
8 #define BLK_BATCH_REQ 32
10 extern struct kmem_cache *blk_requestq_cachep;
11 extern struct kobj_type blk_queue_ktype;
13 void init_request_from_bio(struct request *req, struct bio *bio);
14 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
16 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
18 void blk_dequeue_request(struct request *rq);
19 void __blk_queue_free_tags(struct request_queue *q);
21 void blk_rq_timed_out_timer(unsigned long data);
22 void blk_delete_timer(struct request *);
23 void blk_add_timer(struct request *);
24 void __generic_unplug_device(struct request_queue *);
27 * Internal atomic flags for request handling
29 enum rq_atomic_flags {
30 REQ_ATOM_COMPLETE = 0,
34 * EH timer and IO completion will both attempt to 'grab' the request, make
35 * sure that only one of them succeeds
37 static inline int blk_mark_rq_complete(struct request *rq)
39 return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
42 static inline void blk_clear_rq_complete(struct request *rq)
44 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
48 * Internal elevator interface
50 #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash))
52 void blk_insert_flush(struct request *rq);
53 void blk_abort_flushes(struct request_queue *q);
55 static inline struct request *__elv_next_request(struct request_queue *q)
60 if (!list_empty(&q->queue_head)) {
61 rq = list_entry_rq(q->queue_head.next);
65 * Flush request is running and flush request isn't queueable
66 * in the drive, we can hold the queue till flush request is
67 * finished. Even we don't do this, driver can't dispatch next
68 * requests and will requeue them. And this can improve
69 * throughput too. For example, we have request flush1, write1,
70 * flush 2. flush1 is dispatched, then queue is hold, write1
71 * isn't inserted to queue. After flush1 is finished, flush2
72 * will be dispatched. Since disk cache is already clean,
73 * flush2 will be finished very soon, so looks like flush2 is
75 * Since the queue is hold, a flag is set to indicate the queue
76 * should be restarted later. Please see flush_end_io() for
79 if (q->flush_pending_idx != q->flush_running_idx &&
80 !queue_flush_queueable(q)) {
81 q->flush_queue_delayed = 1;
84 if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
89 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
91 struct elevator_queue *e = q->elevator;
93 if (e->ops->elevator_activate_req_fn)
94 e->ops->elevator_activate_req_fn(q, rq);
97 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
99 struct elevator_queue *e = q->elevator;
101 if (e->ops->elevator_deactivate_req_fn)
102 e->ops->elevator_deactivate_req_fn(q, rq);
105 #ifdef CONFIG_FAIL_IO_TIMEOUT
106 int blk_should_fake_timeout(struct request_queue *);
107 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
108 ssize_t part_timeout_store(struct device *, struct device_attribute *,
109 const char *, size_t);
111 static inline int blk_should_fake_timeout(struct request_queue *q)
117 struct io_context *current_io_context(gfp_t gfp_flags, int node);
119 int ll_back_merge_fn(struct request_queue *q, struct request *req,
121 int ll_front_merge_fn(struct request_queue *q, struct request *req,
123 int attempt_back_merge(struct request_queue *q, struct request *rq);
124 int attempt_front_merge(struct request_queue *q, struct request *rq);
125 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
126 struct request *next);
127 void blk_recalc_rq_segments(struct request *rq);
128 void blk_rq_set_mixed_merge(struct request *rq);
130 void blk_queue_congestion_threshold(struct request_queue *q);
132 int blk_dev_init(void);
134 void elv_quiesce_start(struct request_queue *q);
135 void elv_quiesce_end(struct request_queue *q);
139 * Return the threshold (number of used requests) at which the queue is
140 * considered to be congested. It include a little hysteresis to keep the
141 * context switch rate down.
143 static inline int queue_congestion_on_threshold(struct request_queue *q)
145 return q->nr_congestion_on;
149 * The threshold at which a queue is considered to be uncongested
151 static inline int queue_congestion_off_threshold(struct request_queue *q)
153 return q->nr_congestion_off;
156 static inline int blk_cpu_to_group(int cpu)
159 #ifdef CONFIG_SCHED_MC
160 const struct cpumask *mask = cpu_coregroup_mask(cpu);
161 group = cpumask_first(mask);
162 #elif defined(CONFIG_SCHED_SMT)
163 group = cpumask_first(topology_thread_cpumask(cpu));
167 if (likely(group < NR_CPUS))
173 * Contribute to IO statistics IFF:
175 * a) it's attached to a gendisk, and
176 * b) the queue had IO stats enabled when this request was started, and
177 * c) it's a file system request or a discard request
179 static inline int blk_do_io_stat(struct request *rq)
181 return rq->rq_disk &&
182 (rq->cmd_flags & REQ_IO_STAT) &&
183 (rq->cmd_type == REQ_TYPE_FS ||
184 (rq->cmd_flags & REQ_DISCARD));