[linux-2.6-block.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

/* Max future timer expiry for timeouts */
#define BLK_MAX_TIMEOUT		(5 * HZ)

struct blk_flush_queue {
	unsigned int		flush_queue_delayed:1;
	unsigned int		flush_pending_idx:1;
	unsigned int		flush_running_idx:1;
	unsigned long		flush_pending_since;
	struct list_head	flush_queue[2];
	struct list_head	flush_data_in_flight;
	struct request		*flush_rq;
	spinlock_t		mq_flush_lock;
};

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

static inline struct blk_flush_queue *blk_get_flush_queue(
		struct request_queue *q)
{
	return q->fq;
}

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

struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q);
void blk_free_flush_queue(struct blk_flush_queue *fq);

int blk_init_rl(struct request_list *rl, struct request_queue *q,
		gfp_t gfp_mask);
void blk_exit_rl(struct request_list *rl);
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);
unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);
void blk_delete_timer(struct request *);


bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
			     struct bio *bio);
bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
			    struct bio *bio);
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
			    unsigned int *request_count);

void blk_account_io_start(struct request *req, bool new_io);
void blk_account_io_completion(struct request *req, unsigned int bytes);
void blk_account_io_done(struct request *req);

/*
 * Internal atomic flags for request handling
 */
enum rq_atomic_flags {
	REQ_ATOM_COMPLETE = 0,
	REQ_ATOM_STARTED,
};

/*
 * 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) ((rq)->cmd_flags & REQ_HASHED)

void blk_insert_flush(struct request *rq);

static inline struct request *__elv_next_request(struct request_queue *q)
{
	struct request *rq;
	struct blk_flush_queue *fq = blk_get_flush_queue(q);

	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 (fq->flush_pending_idx != fq->flush_running_idx &&
				!queue_flush_queueable(q)) {
			fq->flush_queue_delayed = 1;
			return NULL;
		}
		if (unlikely(blk_queue_bypass(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);

void __blk_run_queue_uncond(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;
}

extern int blk_update_nr_requests(struct request_queue *, unsigned int);

/*
 * 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
 */
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);
}

/*
 * 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
8324aa91 JA	1	#ifndef BLK_INTERNAL_H
	2	#define BLK_INTERNAL_H
	3
a73f730d TH	4	#include <linux/idr.h>
a73f730d TH	5
86db1e29 JA	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
0d2602ca JA	12	/* Max future timer expiry for timeouts */
	13	#define BLK_MAX_TIMEOUT (5 * HZ)
	14
7c94e1c1 ML	15	struct blk_flush_queue {
	16	unsigned int flush_queue_delayed:1;
	17	unsigned int flush_pending_idx:1;
	18	unsigned int flush_running_idx:1;
	19	unsigned long flush_pending_since;
	20	struct list_head flush_queue[2];
	21	struct list_head flush_data_in_flight;
	22	struct request *flush_rq;
	23	spinlock_t mq_flush_lock;
	24	};
	25
8324aa91	26	extern struct kmem_cache *blk_requestq_cachep;
320ae51f	27	extern struct kmem_cache *request_cachep;
8324aa91	28	extern struct kobj_type blk_queue_ktype;
a73f730d	29	extern struct ida blk_queue_ida;
8324aa91	30
7c94e1c1 ML	31	static inline struct blk_flush_queue *blk_get_flush_queue(
	32	struct request_queue *q)
	33	{
	34	return q->fq;
	35	}
	36
09ac46c4 TH	37	static inline void __blk_get_queue(struct request_queue *q)
	38	{
	39	kobject_get(&q->kobj);
	40	}
	41
ba483388 ML	42	struct blk_flush_queue blk_alloc_flush_queue(struct request_queue q);
ba483388 ML	43	void blk_free_flush_queue(struct blk_flush_queue *fq);
f3552655	44
5b788ce3 TH	45	int blk_init_rl(struct request_list rl, struct request_queue q,
	46	gfp_t gfp_mask);
	47	void blk_exit_rl(struct request_list *rl);
86db1e29 JA	48	void init_request_from_bio(struct request req, struct bio bio);
	49	void blk_rq_bio_prep(struct request_queue q, struct request rq,
	50	struct bio *bio);
a411f4bb BH	51	int blk_rq_append_bio(struct request_queue q, struct request rq,
a411f4bb BH	52	struct bio *bio);
d732580b TH	53	void blk_queue_bypass_start(struct request_queue *q);
d732580b TH	54	void blk_queue_bypass_end(struct request_queue *q);
9934c8c0	55	void blk_dequeue_request(struct request *rq);
8324aa91	56	void __blk_queue_free_tags(struct request_queue *q);
4853abaa JM	57	bool __blk_end_bidi_request(struct request *rq, int error,
4853abaa JM	58	unsigned int nr_bytes, unsigned int bidi_bytes);
8324aa91	59
242f9dcb	60	void blk_rq_timed_out_timer(unsigned long data);
0d2602ca	61	unsigned long blk_rq_timeout(unsigned long timeout);
87ee7b11	62	void blk_add_timer(struct request *req);
242f9dcb	63	void blk_delete_timer(struct request *);
242f9dcb	64
320ae51f JA	65
	66	bool bio_attempt_front_merge(struct request_queue q, struct request req,
	67	struct bio *bio);
	68	bool bio_attempt_back_merge(struct request_queue q, struct request req,
	69	struct bio *bio);
	70	bool blk_attempt_plug_merge(struct request_queue q, struct bio bio,
	71	unsigned int *request_count);
	72
	73	void blk_account_io_start(struct request *req, bool new_io);
	74	void blk_account_io_completion(struct request *req, unsigned int bytes);
	75	void blk_account_io_done(struct request *req);
	76
242f9dcb JA	77	/*
	78	* Internal atomic flags for request handling
	79	*/
	80	enum rq_atomic_flags {
	81	REQ_ATOM_COMPLETE = 0,
320ae51f	82	REQ_ATOM_STARTED,
242f9dcb JA	83	};
	84
	85	/*
	86	* EH timer and IO completion will both attempt to 'grab' the request, make
25985edc	87	* sure that only one of them succeeds
242f9dcb JA	88	*/
	89	static inline int blk_mark_rq_complete(struct request *rq)
	90	{
	91	return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
	92	}
	93
	94	static inline void blk_clear_rq_complete(struct request *rq)
	95	{
	96	clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
	97	}
86db1e29	98
158dbda0 TH	99	/*
	100	* Internal elevator interface
	101	*/
360f92c2	102	#define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
158dbda0	103
ae1b1539	104	void blk_insert_flush(struct request *rq);
dd831006	105
158dbda0 TH	106	static inline struct request __elv_next_request(struct request_queue q)
	107	{
	108	struct request *rq;
7c94e1c1	109	struct blk_flush_queue *fq = blk_get_flush_queue(q);
158dbda0 TH	110
158dbda0 TH	111	while (1) {
ae1b1539	112	if (!list_empty(&q->queue_head)) {
158dbda0	113	rq = list_entry_rq(q->queue_head.next);
ae1b1539	114	return rq;
158dbda0 TH	115	}
158dbda0 TH	116
3ac0cc45	117	/*
	118	* Flush request is running and flush request isn't queueable
	119	* in the drive, we can hold the queue till flush request is
	120	* finished. Even we don't do this, driver can't dispatch next
	121	* requests and will requeue them. And this can improve
	122	* throughput too. For example, we have request flush1, write1,
	123	* flush 2. flush1 is dispatched, then queue is hold, write1
	124	* isn't inserted to queue. After flush1 is finished, flush2
	125	* will be dispatched. Since disk cache is already clean,
	126	* flush2 will be finished very soon, so looks like flush2 is
	127	* folded to flush1.
	128	* Since the queue is hold, a flag is set to indicate the queue
	129	* should be restarted later. Please see flush_end_io() for
	130	* details.
	131	*/
7c94e1c1	132	if (fq->flush_pending_idx != fq->flush_running_idx &&
3ac0cc45	133	!queue_flush_queueable(q)) {
7c94e1c1	134	fq->flush_queue_delayed = 1;
3ac0cc45	135	return NULL;
3ac0cc45	136	}
556ee818	137	if (unlikely(blk_queue_bypass(q)) \|\|
22f746e2	138	!q->elevator->type->ops.elevator_dispatch_fn(q, 0))
158dbda0 TH	139	return NULL;
	140	}
	141	}
	142
	143	static inline void elv_activate_rq(struct request_queue q, struct request rq)
	144	{
	145	struct elevator_queue *e = q->elevator;
	146
22f746e2 TH	147	if (e->type->ops.elevator_activate_req_fn)
22f746e2 TH	148	e->type->ops.elevator_activate_req_fn(q, rq);
158dbda0 TH	149	}
	150
	151	static inline void elv_deactivate_rq(struct request_queue q, struct request rq)
	152	{
	153	struct elevator_queue *e = q->elevator;
	154
22f746e2 TH	155	if (e->type->ops.elevator_deactivate_req_fn)
22f746e2 TH	156	e->type->ops.elevator_deactivate_req_fn(q, rq);
158dbda0 TH	157	}
158dbda0 TH	158
581d4e28 JA	159	#ifdef CONFIG_FAIL_IO_TIMEOUT
	160	int blk_should_fake_timeout(struct request_queue *);
	161	ssize_t part_timeout_show(struct device , struct device_attribute , char *);
	162	ssize_t part_timeout_store(struct device , struct device_attribute ,
	163	const char *, size_t);
	164	#else
	165	static inline int blk_should_fake_timeout(struct request_queue *q)
	166	{
	167	return 0;
	168	}
	169	#endif
	170
d6d48196 JA	171	int ll_back_merge_fn(struct request_queue q, struct request req,
	172	struct bio *bio);
	173	int ll_front_merge_fn(struct request_queue q, struct request req,
	174	struct bio *bio);
	175	int attempt_back_merge(struct request_queue q, struct request rq);
	176	int attempt_front_merge(struct request_queue q, struct request rq);
5e84ea3a JA	177	int blk_attempt_req_merge(struct request_queue q, struct request rq,
5e84ea3a JA	178	struct request *next);
d6d48196	179	void blk_recalc_rq_segments(struct request *rq);
80a761fd	180	void blk_rq_set_mixed_merge(struct request *rq);
050c8ea8 TH	181	bool blk_rq_merge_ok(struct request rq, struct bio bio);
050c8ea8 TH	182	int blk_try_merge(struct request rq, struct bio bio);
d6d48196	183
8324aa91 JA	184	void blk_queue_congestion_threshold(struct request_queue *q);
8324aa91 JA	185
c246e80d BVA	186	void __blk_run_queue_uncond(struct request_queue *q);
c246e80d BVA	187
ff88972c AB	188	int blk_dev_init(void);
ff88972c AB	189
f253b86b	190
8324aa91 JA	191	/*
	192	* Return the threshold (number of used requests) at which the queue is
	193	* considered to be congested. It include a little hysteresis to keep the
	194	* context switch rate down.
	195	*/
	196	static inline int queue_congestion_on_threshold(struct request_queue *q)
	197	{
	198	return q->nr_congestion_on;
	199	}
	200
	201	/*
	202	* The threshold at which a queue is considered to be uncongested
	203	*/
	204	static inline int queue_congestion_off_threshold(struct request_queue *q)
	205	{
	206	return q->nr_congestion_off;
	207	}
	208
e3a2b3f9 JA	209	extern int blk_update_nr_requests(struct request_queue *, unsigned int);
e3a2b3f9 JA	210
c2553b58 JA	211	/*
	212	* Contribute to IO statistics IFF:
	213	*
	214	* a) it's attached to a gendisk, and
	215	* b) the queue had IO stats enabled when this request was started, and
e2a60da7	216	* c) it's a file system request
c2553b58	217	*/
26308eab	218	static inline int blk_do_io_stat(struct request *rq)
fb8ec18c	219	{
33659ebb CH	220	return rq->rq_disk &&
33659ebb CH	221	(rq->cmd_flags & REQ_IO_STAT) &&
e2a60da7	222	(rq->cmd_type == REQ_TYPE_FS);
fb8ec18c JA	223	}
fb8ec18c JA	224
f2dbd76a TH	225	/*
	226	* Internal io_context interface
	227	*/
	228	void get_io_context(struct io_context *ioc);
47fdd4ca	229	struct io_cq ioc_lookup_icq(struct io_context ioc, struct request_queue *q);
24acfc34 TH	230	struct io_cq ioc_create_icq(struct io_context ioc, struct request_queue *q,
24acfc34 TH	231	gfp_t gfp_mask);
7e5a8794	232	void ioc_clear_queue(struct request_queue *q);
f2dbd76a	233
24acfc34	234	int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
f2dbd76a TH	235
	236	/**
	237	* create_io_context - try to create task->io_context
f2dbd76a TH	238	* @gfp_mask: allocation mask
	239	* @node: allocation node
	240	*
24acfc34 TH	241	* If %current->io_context is %NULL, allocate a new io_context and install
	242	* it. Returns the current %current->io_context which may be %NULL if
	243	* allocation failed.
f2dbd76a TH	244	*
f2dbd76a TH	245	* Note that this function can't be called with IRQ disabled because
24acfc34	246	* task_lock which protects %current->io_context is IRQ-unsafe.
f2dbd76a	247	*/
24acfc34	248	static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
f2dbd76a TH	249	{
f2dbd76a TH	250	WARN_ON_ONCE(irqs_disabled());
24acfc34 TH	251	if (unlikely(!current->io_context))
	252	create_task_io_context(current, gfp_mask, node);
	253	return current->io_context;
f2dbd76a TH	254	}
	255
	256	/*
	257	* Internal throttling interface
	258	*/
bc9fcbf9	259	#ifdef CONFIG_BLK_DEV_THROTTLING
bc16a4f9	260	extern bool blk_throtl_bio(struct request_queue q, struct bio bio);
c9a929dd	261	extern void blk_throtl_drain(struct request_queue *q);
bc9fcbf9 TH	262	extern int blk_throtl_init(struct request_queue *q);
	263	extern void blk_throtl_exit(struct request_queue *q);
	264	#else /* CONFIG_BLK_DEV_THROTTLING */
bc16a4f9	265	static inline bool blk_throtl_bio(struct request_queue q, struct bio bio)
bc9fcbf9	266	{
bc16a4f9	267	return false;
bc9fcbf9	268	}
c9a929dd	269	static inline void blk_throtl_drain(struct request_queue *q) { }
bc9fcbf9 TH	270	static inline int blk_throtl_init(struct request_queue *q) { return 0; }
	271	static inline void blk_throtl_exit(struct request_queue *q) { }
	272	#endif /* CONFIG_BLK_DEV_THROTTLING */
	273
	274	#endif /* BLK_INTERNAL_H */