[mirror_ubuntu-artful-kernel.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)

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

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);
void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
			  unsigned int *next_set);
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;

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