blk.h 4.6 KB
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#ifndef BLK_INTERNAL_H
#define BLK_INTERNAL_H

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/* Amount of time in which a process may batch requests */
#define BLK_BATCH_TIME	(HZ/50UL)

/* Number of requests a "batching" process may submit */
#define BLK_BATCH_REQ	32

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extern struct kmem_cache *blk_requestq_cachep;
extern struct kobj_type blk_queue_ktype;

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void init_request_from_bio(struct request *req, struct bio *bio);
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
			struct bio *bio);
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int blk_rq_append_bio(struct request_queue *q, struct request *rq,
		      struct bio *bio);
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void blk_dequeue_request(struct request *rq);
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void __blk_queue_free_tags(struct request_queue *q);

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void blk_unplug_work(struct work_struct *work);
void blk_unplug_timeout(unsigned long data);
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void blk_rq_timed_out_timer(unsigned long data);
void blk_delete_timer(struct request *);
void blk_add_timer(struct request *);
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void __generic_unplug_device(struct request_queue *);
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/*
 * Internal atomic flags for request handling
 */
enum rq_atomic_flags {
	REQ_ATOM_COMPLETE = 0,
};

/*
 * EH timer and IO completion will both attempt to 'grab' the request, make
 * sure that only one of them suceeds
 */
static inline int blk_mark_rq_complete(struct request *rq)
{
	return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
}

static inline void blk_clear_rq_complete(struct request *rq)
{
	clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
}
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/*
 * Internal elevator interface
 */
#define ELV_ON_HASH(rq)		(!hlist_unhashed(&(rq)->hash))

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struct request *blk_do_flush(struct request_queue *q, struct request *rq);
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static inline struct request *__elv_next_request(struct request_queue *q)
{
	struct request *rq;

	while (1) {
		while (!list_empty(&q->queue_head)) {
			rq = list_entry_rq(q->queue_head.next);
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			if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) ||
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			    (rq->cmd_flags & REQ_FLUSH_SEQ))
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				return rq;
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			rq = blk_do_flush(q, rq);
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			if (rq)
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				return rq;
		}

		if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
			return NULL;
	}
}

static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
{
	struct elevator_queue *e = q->elevator;

	if (e->ops->elevator_activate_req_fn)
		e->ops->elevator_activate_req_fn(q, rq);
}

static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
{
	struct elevator_queue *e = q->elevator;

	if (e->ops->elevator_deactivate_req_fn)
		e->ops->elevator_deactivate_req_fn(q, rq);
}

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#ifdef CONFIG_FAIL_IO_TIMEOUT
int blk_should_fake_timeout(struct request_queue *);
ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
ssize_t part_timeout_store(struct device *, struct device_attribute *,
				const char *, size_t);
#else
static inline int blk_should_fake_timeout(struct request_queue *q)
{
	return 0;
}
#endif

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struct io_context *current_io_context(gfp_t gfp_flags, int node);

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int ll_back_merge_fn(struct request_queue *q, struct request *req,
		     struct bio *bio);
int ll_front_merge_fn(struct request_queue *q, struct request *req, 
		      struct bio *bio);
int attempt_back_merge(struct request_queue *q, struct request *rq);
int attempt_front_merge(struct request_queue *q, struct request *rq);
void blk_recalc_rq_segments(struct request *rq);
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void blk_rq_set_mixed_merge(struct request *rq);
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void blk_queue_congestion_threshold(struct request_queue *q);

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int blk_dev_init(void);

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void elv_quiesce_start(struct request_queue *q);
void elv_quiesce_end(struct request_queue *q);


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/*
 * Return the threshold (number of used requests) at which the queue is
 * considered to be congested.  It include a little hysteresis to keep the
 * context switch rate down.
 */
static inline int queue_congestion_on_threshold(struct request_queue *q)
{
	return q->nr_congestion_on;
}

/*
 * The threshold at which a queue is considered to be uncongested
 */
static inline int queue_congestion_off_threshold(struct request_queue *q)
{
	return q->nr_congestion_off;
}

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static inline int blk_cpu_to_group(int cpu)
{
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	int group = NR_CPUS;
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#ifdef CONFIG_SCHED_MC
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	const struct cpumask *mask = cpu_coregroup_mask(cpu);
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	group = cpumask_first(mask);
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#elif defined(CONFIG_SCHED_SMT)
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	group = cpumask_first(topology_thread_cpumask(cpu));
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#else
	return cpu;
#endif
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	if (likely(group < NR_CPUS))
		return group;
	return cpu;
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}

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/*
 * Contribute to IO statistics IFF:
 *
 *	a) it's attached to a gendisk, and
 *	b) the queue had IO stats enabled when this request was started, and
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 *	c) it's a file system request or a discard request
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 */
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static inline int blk_do_io_stat(struct request *rq)
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{
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	return rq->rq_disk &&
	       (rq->cmd_flags & REQ_IO_STAT) &&
	       (rq->cmd_type == REQ_TYPE_FS ||
	        (rq->cmd_flags & REQ_DISCARD));
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}

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#endif