[deliverable/linux.git] / block / blk.h

#ifndef BLK_INTERNAL_H
#define BLK_INTERNAL_H

#include <linux/idr.h>

/* 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

extern struct kmem_cache *blk_requestq_cachep;
extern struct kobj_type blk_queue_ktype;
extern struct ida blk_queue_ida;

static inline void __blk_get_queue(struct request_queue *q)
{
	kobject_get(&q->kobj);
}

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);
int blk_rq_append_bio(struct request_queue *q, struct request *rq,
		      struct bio *bio);
void blk_queue_bypass_start(struct request_queue *q);
void blk_queue_bypass_end(struct request_queue *q);
void blk_dequeue_request(struct request *rq);
void __blk_queue_free_tags(struct request_queue *q);
bool __blk_end_bidi_request(struct request *rq, int error,
			    unsigned int nr_bytes, unsigned int bidi_bytes);

void blk_rq_timed_out_timer(unsigned long data);
void blk_delete_timer(struct request *);
void blk_add_timer(struct request *);
void __generic_unplug_device(struct request_queue *);

/*
 * 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 succeeds
 */
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);
}

/*
 * Internal elevator interface
 */
#define ELV_ON_HASH(rq)		(!hlist_unhashed(&(rq)->hash))

void blk_insert_flush(struct request *rq);
void blk_abort_flushes(struct request_queue *q);

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

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

		/*
		 * 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;
		}
		if (unlikely(blk_queue_dead(q)) ||
		    !q->elevator->type->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->type->ops.elevator_activate_req_fn)
		e->type->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->type->ops.elevator_deactivate_req_fn)
		e->type->ops.elevator_deactivate_req_fn(q, rq);
}

#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

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);
int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
				struct request *next);
void blk_recalc_rq_segments(struct request *rq);
void blk_rq_set_mixed_merge(struct request *rq);
bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
int blk_try_merge(struct request *rq, struct bio *bio);

void blk_queue_congestion_threshold(struct request_queue *q);

int blk_dev_init(void);


/*
 * 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;
}

/*
 * 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
 *	c) it's a file system request or a discard request
 */
static inline int blk_do_io_stat(struct request *rq)
{
	return rq->rq_disk &&
	       (rq->cmd_flags & REQ_IO_STAT) &&
	       (rq->cmd_type == REQ_TYPE_FS ||
	        (rq->cmd_flags & REQ_DISCARD));
}

/*
 * Internal io_context interface
 */
void get_io_context(struct io_context *ioc);
struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
			     gfp_t gfp_mask);
void ioc_clear_queue(struct request_queue *q);

int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);

/**
 * create_io_context - try to create task->io_context
 * @gfp_mask: allocation mask
 * @node: allocation node
 *
 * If %current->io_context is %NULL, allocate a new io_context and install
 * it.  Returns the current %current->io_context which may be %NULL if
 * allocation failed.
 *
 * Note that this function can't be called with IRQ disabled because
 * task_lock which protects %current->io_context is IRQ-unsafe.
 */
static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
{
	WARN_ON_ONCE(irqs_disabled());
	if (unlikely(!current->io_context))
		create_task_io_context(current, gfp_mask, node);
	return current->io_context;
}

/*
 * Internal throttling interface
 */
#ifdef CONFIG_BLK_DEV_THROTTLING
extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
extern void blk_throtl_drain(struct request_queue *q);
extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
#else /* CONFIG_BLK_DEV_THROTTLING */
static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
{
	return false;
}
static inline void blk_throtl_drain(struct request_queue *q) { }
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
#endif /* CONFIG_BLK_DEV_THROTTLING */

#endif /* BLK_INTERNAL_H */
Commit	Line	Data
	1	#ifndef BLK_INTERNAL_H
	2	#define BLK_INTERNAL_H
	3
	4	#include <linux/idr.h>
	5
	6	/* Amount of time in which a process may batch requests */
	7	#define BLK_BATCH_TIME (HZ/50UL)
	8
	9	/* Number of requests a "batching" process may submit */
	10	#define BLK_BATCH_REQ 32
	11
	12	extern struct kmem_cache *blk_requestq_cachep;
	13	extern struct kobj_type blk_queue_ktype;
	14	extern struct ida blk_queue_ida;
	15
	16	static inline void __blk_get_queue(struct request_queue *q)
	17	{
	18	kobject_get(&q->kobj);
	19	}
	20
	21	void init_request_from_bio(struct request req, struct bio bio);
	22	void blk_rq_bio_prep(struct request_queue q, struct request rq,
	23	struct bio *bio);
	24	int blk_rq_append_bio(struct request_queue q, struct request rq,
	25	struct bio *bio);
	26	void blk_queue_bypass_start(struct request_queue *q);
	27	void blk_queue_bypass_end(struct request_queue *q);
	28	void blk_dequeue_request(struct request *rq);
	29	void __blk_queue_free_tags(struct request_queue *q);
	30	bool __blk_end_bidi_request(struct request *rq, int error,
	31	unsigned int nr_bytes, unsigned int bidi_bytes);
	32
	33	void blk_rq_timed_out_timer(unsigned long data);
	34	void blk_delete_timer(struct request *);
	35	void blk_add_timer(struct request *);
	36	void __generic_unplug_device(struct request_queue *);
	37
	38	/*
	39	* Internal atomic flags for request handling
	40	*/
	41	enum rq_atomic_flags {
	42	REQ_ATOM_COMPLETE = 0,
	43	};
	44
	45	/*
	46	* EH timer and IO completion will both attempt to 'grab' the request, make
	47	* sure that only one of them succeeds
	48	*/
	49	static inline int blk_mark_rq_complete(struct request *rq)
	50	{
	51	return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
	52	}
	53
	54	static inline void blk_clear_rq_complete(struct request *rq)
	55	{
	56	clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
	57	}
	58
	59	/*
	60	* Internal elevator interface
	61	*/
	62	#define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash))
	63
	64	void blk_insert_flush(struct request *rq);
	65	void blk_abort_flushes(struct request_queue *q);
	66
	67	static inline struct request __elv_next_request(struct request_queue q)
	68	{
	69	struct request *rq;
	70
	71	while (1) {
	72	if (!list_empty(&q->queue_head)) {
	73	rq = list_entry_rq(q->queue_head.next);
	74	return rq;
	75	}
	76
	77	/*
	78	* Flush request is running and flush request isn't queueable
	79	* in the drive, we can hold the queue till flush request is
	80	* finished. Even we don't do this, driver can't dispatch next
	81	* requests and will requeue them. And this can improve
	82	* throughput too. For example, we have request flush1, write1,
	83	* flush 2. flush1 is dispatched, then queue is hold, write1
	84	* isn't inserted to queue. After flush1 is finished, flush2
	85	* will be dispatched. Since disk cache is already clean,
	86	* flush2 will be finished very soon, so looks like flush2 is
	87	* folded to flush1.
	88	* Since the queue is hold, a flag is set to indicate the queue
	89	* should be restarted later. Please see flush_end_io() for
	90	* details.
	91	*/
	92	if (q->flush_pending_idx != q->flush_running_idx &&
	93	!queue_flush_queueable(q)) {
	94	q->flush_queue_delayed = 1;
	95	return NULL;
	96	}
	97	if (unlikely(blk_queue_dead(q)) \|\|
	98	!q->elevator->type->ops.elevator_dispatch_fn(q, 0))
	99	return NULL;
	100	}
	101	}
	102
	103	static inline void elv_activate_rq(struct request_queue q, struct request rq)
	104	{
	105	struct elevator_queue *e = q->elevator;
	106
	107	if (e->type->ops.elevator_activate_req_fn)
	108	e->type->ops.elevator_activate_req_fn(q, rq);
	109	}
	110
	111	static inline void elv_deactivate_rq(struct request_queue q, struct request rq)
	112	{
	113	struct elevator_queue *e = q->elevator;
	114
	115	if (e->type->ops.elevator_deactivate_req_fn)
	116	e->type->ops.elevator_deactivate_req_fn(q, rq);
	117	}
	118
	119	#ifdef CONFIG_FAIL_IO_TIMEOUT
	120	int blk_should_fake_timeout(struct request_queue *);
	121	ssize_t part_timeout_show(struct device , struct device_attribute , char *);
	122	ssize_t part_timeout_store(struct device , struct device_attribute ,
	123	const char *, size_t);
	124	#else
	125	static inline int blk_should_fake_timeout(struct request_queue *q)
	126	{
	127	return 0;
	128	}
	129	#endif
	130
	131	int ll_back_merge_fn(struct request_queue q, struct request req,
	132	struct bio *bio);
	133	int ll_front_merge_fn(struct request_queue q, struct request req,
	134	struct bio *bio);
	135	int attempt_back_merge(struct request_queue q, struct request rq);
	136	int attempt_front_merge(struct request_queue q, struct request rq);
	137	int blk_attempt_req_merge(struct request_queue q, struct request rq,
	138	struct request *next);
	139	void blk_recalc_rq_segments(struct request *rq);
	140	void blk_rq_set_mixed_merge(struct request *rq);
	141	bool blk_rq_merge_ok(struct request rq, struct bio bio);
	142	int blk_try_merge(struct request rq, struct bio bio);
	143
	144	void blk_queue_congestion_threshold(struct request_queue *q);
	145
	146	int blk_dev_init(void);
	147
	148
	149	/*
	150	* Return the threshold (number of used requests) at which the queue is
	151	* considered to be congested. It include a little hysteresis to keep the
	152	* context switch rate down.
	153	*/
	154	static inline int queue_congestion_on_threshold(struct request_queue *q)
	155	{
	156	return q->nr_congestion_on;
	157	}
	158
	159	/*
	160	* The threshold at which a queue is considered to be uncongested
	161	*/
	162	static inline int queue_congestion_off_threshold(struct request_queue *q)
	163	{
	164	return q->nr_congestion_off;
	165	}
	166
	167	/*
	168	* Contribute to IO statistics IFF:
	169	*
	170	* a) it's attached to a gendisk, and
	171	* b) the queue had IO stats enabled when this request was started, and
	172	* c) it's a file system request or a discard request
	173	*/
	174	static inline int blk_do_io_stat(struct request *rq)
	175	{
	176	return rq->rq_disk &&
	177	(rq->cmd_flags & REQ_IO_STAT) &&
	178	(rq->cmd_type == REQ_TYPE_FS \|\|
	179	(rq->cmd_flags & REQ_DISCARD));
	180	}
	181
	182	/*
	183	* Internal io_context interface
	184	*/
	185	void get_io_context(struct io_context *ioc);
	186	struct io_cq ioc_lookup_icq(struct io_context ioc, struct request_queue *q);
	187	struct io_cq ioc_create_icq(struct io_context ioc, struct request_queue *q,
	188	gfp_t gfp_mask);
	189	void ioc_clear_queue(struct request_queue *q);
	190
	191	int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
	192
	193	/**
	194	* create_io_context - try to create task->io_context
	195	* @gfp_mask: allocation mask
	196	* @node: allocation node
	197	*
	198	* If %current->io_context is %NULL, allocate a new io_context and install
	199	* it. Returns the current %current->io_context which may be %NULL if
	200	* allocation failed.
	201	*
	202	* Note that this function can't be called with IRQ disabled because
	203	* task_lock which protects %current->io_context is IRQ-unsafe.
	204	*/
	205	static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
	206	{
	207	WARN_ON_ONCE(irqs_disabled());
	208	if (unlikely(!current->io_context))
	209	create_task_io_context(current, gfp_mask, node);
	210	return current->io_context;
	211	}
	212
	213	/*
	214	* Internal throttling interface
	215	*/
	216	#ifdef CONFIG_BLK_DEV_THROTTLING
	217	extern bool blk_throtl_bio(struct request_queue q, struct bio bio);
	218	extern void blk_throtl_drain(struct request_queue *q);
	219	extern int blk_throtl_init(struct request_queue *q);
	220	extern void blk_throtl_exit(struct request_queue *q);
	221	#else /* CONFIG_BLK_DEV_THROTTLING */
	222	static inline bool blk_throtl_bio(struct request_queue q, struct bio bio)
	223	{
	224	return false;
	225	}
	226	static inline void blk_throtl_drain(struct request_queue *q) { }
	227	static inline int blk_throtl_init(struct request_queue *q) { return 0; }
	228	static inline void blk_throtl_exit(struct request_queue *q) { }
	229	#endif /* CONFIG_BLK_DEV_THROTTLING */
	230
	231	#endif /* BLK_INTERNAL_H */