blk.h 6.3 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_drain_queue(struct request_queue *q, bool drain_all);
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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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bool __blk_end_bidi_request(struct request *rq, int error,
			    unsigned int nr_bytes, unsigned int bidi_bytes);
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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
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 * sure that only one of them succeeds
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 */
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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void blk_insert_flush(struct request *rq);
void blk_abort_flushes(struct request_queue *q);
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static inline struct request *__elv_next_request(struct request_queue *q)
{
	struct request *rq;

	while (1) {
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		if (!list_empty(&q->queue_head)) {
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			rq = list_entry_rq(q->queue_head.next);
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			return rq;
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		}

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		/*
		 * Flush request is running and flush request isn't queueable
		 * in the drive, we can hold the queue till flush request is
		 * finished. Even we don't do this, driver can't dispatch next
		 * requests and will requeue them. And this can improve
		 * throughput too. For example, we have request flush1, write1,
		 * flush 2. flush1 is dispatched, then queue is hold, write1
		 * isn't inserted to queue. After flush1 is finished, flush2
		 * will be dispatched. Since disk cache is already clean,
		 * flush2 will be finished very soon, so looks like flush2 is
		 * folded to flush1.
		 * Since the queue is hold, a flag is set to indicate the queue
		 * should be restarted later. Please see flush_end_io() for
		 * details.
		 */
		if (q->flush_pending_idx != q->flush_running_idx &&
				!queue_flush_queueable(q)) {
			q->flush_queue_delayed = 1;
			return NULL;
		}
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		if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
		    !q->elevator->ops->elevator_dispatch_fn(q, 0))
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			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);
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int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
				struct request *next);
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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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#ifdef CONFIG_BLK_DEV_THROTTLING
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extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
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extern void blk_throtl_drain(struct request_queue *q);
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extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
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extern void blk_throtl_release(struct request_queue *q);
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#else /* CONFIG_BLK_DEV_THROTTLING */
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static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
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{
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	return false;
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}
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static inline void blk_throtl_drain(struct request_queue *q) { }
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static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
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static inline void blk_throtl_release(struct request_queue *q) { }
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#endif /* CONFIG_BLK_DEV_THROTTLING */

#endif /* BLK_INTERNAL_H */