[mirror_ubuntu-artful-kernel.git] / block / blk.h

#ifndef BLK_INTERNAL_H
#define BLK_INTERNAL_H

#include <linux/idr.h>
#include <linux/blk-mq.h>
#include "blk-mq.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)

#ifdef CONFIG_DEBUG_FS
extern struct dentry *blk_debugfs_root;
#endif

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;

	/*
	 * flush_rq shares tag with this rq, both can't be active
	 * at the same time
	 */
	struct request		*orig_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, struct blk_mq_ctx *ctx)
{
	if (q->mq_ops)
		return blk_mq_map_queue(q, ctx->cpu)->fq;
	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,
		int node, int cmd_size);
void blk_free_flush_queue(struct blk_flush_queue *q);

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);
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_freeze_queue(struct request_queue *q);

static inline void blk_queue_enter_live(struct request_queue *q)
{
	/*
	 * Given that running in generic_make_request() context
	 * guarantees that a live reference against q_usage_counter has
	 * been established, further references under that same context
	 * need not check that the queue has been frozen (marked dead).
	 */
	percpu_ref_get(&q->q_usage_counter);
}

#ifdef CONFIG_BLK_DEV_INTEGRITY
void blk_flush_integrity(void);
#else
static inline void blk_flush_integrity(void)
{
}
#endif

void blk_timeout_work(struct work_struct *work);
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 bio_attempt_discard_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,
			    struct request **same_queue_rq);
unsigned int blk_plug_queued_count(struct request_queue *q);

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,
	REQ_ATOM_POLL_SLEPT,
};

/*
 * 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)->rq_flags & RQF_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, NULL);

	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.sq.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.sq.elevator_activate_req_fn)
		e->type->ops.sq.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.sq.elevator_deactivate_req_fn)
		e->type->ops.sq.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);
struct request *attempt_back_merge(struct request_queue *q, struct request *rq);
struct request *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);
enum elv_merge 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;
}

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->rq_flags & RQF_IO_STAT) &&
		!blk_rq_is_passthrough(rq);
}

static inline void req_set_nomerge(struct request_queue *q, struct request *req)
{
	req->cmd_flags |= REQ_NOMERGE;
	if (req == q->last_merge)
		q->last_merge = NULL;
}

/*
 * 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);

/**
 * rq_ioc - determine io_context for request allocation
 * @bio: request being allocated is for this bio (can be %NULL)
 *
 * Determine io_context to use for request allocation for @bio.  May return
 * %NULL if %current->io_context doesn't exist.
 */
static inline struct io_context *rq_ioc(struct bio *bio)
{
#ifdef CONFIG_BLK_CGROUP
	if (bio && bio->bi_ioc)
		return bio->bi_ioc;
#endif
	return current->io_context;
}

/**
 * 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 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 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 */
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
	const char *page, size_t count);
#endif

#endif /* BLK_INTERNAL_H */
Commit	Line	Data
8324aa91 JA	1	#ifndef BLK_INTERNAL_H
	2	#define BLK_INTERNAL_H
	3
a73f730d	4	#include <linux/idr.h>
f70ced09 ML	5	#include <linux/blk-mq.h>
f70ced09 ML	6	#include "blk-mq.h"
a73f730d	7
86db1e29 JA	8	/* Amount of time in which a process may batch requests */
	9	#define BLK_BATCH_TIME (HZ/50UL)
	10
	11	/* Number of requests a "batching" process may submit */
	12	#define BLK_BATCH_REQ 32
	13
0d2602ca JA	14	/* Max future timer expiry for timeouts */
	15	#define BLK_MAX_TIMEOUT (5 * HZ)
	16
18fbda91 OS	17	#ifdef CONFIG_DEBUG_FS
	18	extern struct dentry *blk_debugfs_root;
	19	#endif
	20
7c94e1c1 ML	21	struct blk_flush_queue {
	22	unsigned int flush_queue_delayed:1;
	23	unsigned int flush_pending_idx:1;
	24	unsigned int flush_running_idx:1;
	25	unsigned long flush_pending_since;
	26	struct list_head flush_queue[2];
	27	struct list_head flush_data_in_flight;
	28	struct request *flush_rq;
0048b483 ML	29
	30	/*
	31	* flush_rq shares tag with this rq, both can't be active
	32	* at the same time
	33	*/
	34	struct request *orig_rq;
7c94e1c1 ML	35	spinlock_t mq_flush_lock;
	36	};
	37
8324aa91	38	extern struct kmem_cache *blk_requestq_cachep;
320ae51f	39	extern struct kmem_cache *request_cachep;
8324aa91	40	extern struct kobj_type blk_queue_ktype;
a73f730d	41	extern struct ida blk_queue_ida;
8324aa91	42
7c94e1c1	43	static inline struct blk_flush_queue *blk_get_flush_queue(
e97c293c	44	struct request_queue q, struct blk_mq_ctx ctx)
7c94e1c1	45	{
7d7e0f90 CH	46	if (q->mq_ops)
	47	return blk_mq_map_queue(q, ctx->cpu)->fq;
	48	return q->fq;
7c94e1c1 ML	49	}
7c94e1c1 ML	50
09ac46c4 TH	51	static inline void __blk_get_queue(struct request_queue *q)
	52	{
	53	kobject_get(&q->kobj);
	54	}
	55
f70ced09 ML	56	struct blk_flush_queue blk_alloc_flush_queue(struct request_queue q,
	57	int node, int cmd_size);
	58	void blk_free_flush_queue(struct blk_flush_queue *q);
f3552655	59
5b788ce3 TH	60	int blk_init_rl(struct request_list rl, struct request_queue q,
	61	gfp_t gfp_mask);
	62	void blk_exit_rl(struct request_list *rl);
86db1e29 JA	63	void init_request_from_bio(struct request req, struct bio bio);
	64	void blk_rq_bio_prep(struct request_queue q, struct request rq,
	65	struct bio *bio);
d732580b TH	66	void blk_queue_bypass_start(struct request_queue *q);
d732580b TH	67	void blk_queue_bypass_end(struct request_queue *q);
9934c8c0	68	void blk_dequeue_request(struct request *rq);
8324aa91	69	void __blk_queue_free_tags(struct request_queue *q);
4853abaa JM	70	bool __blk_end_bidi_request(struct request *rq, int error,
4853abaa JM	71	unsigned int nr_bytes, unsigned int bidi_bytes);
3ef28e83 DW	72	void blk_freeze_queue(struct request_queue *q);
	73
	74	static inline void blk_queue_enter_live(struct request_queue *q)
	75	{
	76	/*
	77	* Given that running in generic_make_request() context
	78	* guarantees that a live reference against q_usage_counter has
	79	* been established, further references under that same context
	80	* need not check that the queue has been frozen (marked dead).
	81	*/
	82	percpu_ref_get(&q->q_usage_counter);
	83	}
8324aa91	84
5a48fc14 DW	85	#ifdef CONFIG_BLK_DEV_INTEGRITY
	86	void blk_flush_integrity(void);
	87	#else
	88	static inline void blk_flush_integrity(void)
	89	{
	90	}
	91	#endif
8324aa91	92
287922eb	93	void blk_timeout_work(struct work_struct *work);
0d2602ca	94	unsigned long blk_rq_timeout(unsigned long timeout);
87ee7b11	95	void blk_add_timer(struct request *req);
242f9dcb	96	void blk_delete_timer(struct request *);
242f9dcb	97
320ae51f JA	98
	99	bool bio_attempt_front_merge(struct request_queue q, struct request req,
	100	struct bio *bio);
	101	bool bio_attempt_back_merge(struct request_queue q, struct request req,
	102	struct bio *bio);
1e739730 CH	103	bool bio_attempt_discard_merge(struct request_queue q, struct request req,
1e739730 CH	104	struct bio *bio);
320ae51f	105	bool blk_attempt_plug_merge(struct request_queue q, struct bio bio,
5b3f341f SL	106	unsigned int *request_count,
5b3f341f SL	107	struct request **same_queue_rq);
0809e3ac	108	unsigned int blk_plug_queued_count(struct request_queue *q);
320ae51f JA	109
	110	void blk_account_io_start(struct request *req, bool new_io);
	111	void blk_account_io_completion(struct request *req, unsigned int bytes);
	112	void blk_account_io_done(struct request *req);
	113
242f9dcb JA	114	/*
	115	* Internal atomic flags for request handling
	116	*/
	117	enum rq_atomic_flags {
	118	REQ_ATOM_COMPLETE = 0,
320ae51f	119	REQ_ATOM_STARTED,
06426adf	120	REQ_ATOM_POLL_SLEPT,
242f9dcb JA	121	};
	122
	123	/*
	124	* EH timer and IO completion will both attempt to 'grab' the request, make
25985edc	125	* sure that only one of them succeeds
242f9dcb JA	126	*/
	127	static inline int blk_mark_rq_complete(struct request *rq)
	128	{
	129	return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
	130	}
	131
	132	static inline void blk_clear_rq_complete(struct request *rq)
	133	{
	134	clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
	135	}
86db1e29	136
158dbda0 TH	137	/*
	138	* Internal elevator interface
	139	*/
e8064021	140	#define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
158dbda0	141
ae1b1539	142	void blk_insert_flush(struct request *rq);
dd831006	143
158dbda0 TH	144	static inline struct request __elv_next_request(struct request_queue q)
	145	{
	146	struct request *rq;
e97c293c	147	struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
158dbda0 TH	148
158dbda0 TH	149	while (1) {
ae1b1539	150	if (!list_empty(&q->queue_head)) {
158dbda0	151	rq = list_entry_rq(q->queue_head.next);
ae1b1539	152	return rq;
158dbda0 TH	153	}
158dbda0 TH	154
3ac0cc45	155	/*
	156	* Flush request is running and flush request isn't queueable
	157	* in the drive, we can hold the queue till flush request is
	158	* finished. Even we don't do this, driver can't dispatch next
	159	* requests and will requeue them. And this can improve
	160	* throughput too. For example, we have request flush1, write1,
	161	* flush 2. flush1 is dispatched, then queue is hold, write1
	162	* isn't inserted to queue. After flush1 is finished, flush2
	163	* will be dispatched. Since disk cache is already clean,
	164	* flush2 will be finished very soon, so looks like flush2 is
	165	* folded to flush1.
	166	* Since the queue is hold, a flag is set to indicate the queue
	167	* should be restarted later. Please see flush_end_io() for
	168	* details.
	169	*/
7c94e1c1	170	if (fq->flush_pending_idx != fq->flush_running_idx &&
3ac0cc45	171	!queue_flush_queueable(q)) {
7c94e1c1	172	fq->flush_queue_delayed = 1;
3ac0cc45	173	return NULL;
3ac0cc45	174	}
556ee818	175	if (unlikely(blk_queue_bypass(q)) \|\|
c51ca6cf	176	!q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0))
158dbda0 TH	177	return NULL;
	178	}
	179	}
	180
	181	static inline void elv_activate_rq(struct request_queue q, struct request rq)
	182	{
	183	struct elevator_queue *e = q->elevator;
	184
c51ca6cf JA	185	if (e->type->ops.sq.elevator_activate_req_fn)
c51ca6cf JA	186	e->type->ops.sq.elevator_activate_req_fn(q, rq);
158dbda0 TH	187	}
	188
	189	static inline void elv_deactivate_rq(struct request_queue q, struct request rq)
	190	{
	191	struct elevator_queue *e = q->elevator;
	192
c51ca6cf JA	193	if (e->type->ops.sq.elevator_deactivate_req_fn)
c51ca6cf JA	194	e->type->ops.sq.elevator_deactivate_req_fn(q, rq);
158dbda0 TH	195	}
158dbda0 TH	196
581d4e28 JA	197	#ifdef CONFIG_FAIL_IO_TIMEOUT
	198	int blk_should_fake_timeout(struct request_queue *);
	199	ssize_t part_timeout_show(struct device , struct device_attribute , char *);
	200	ssize_t part_timeout_store(struct device , struct device_attribute ,
	201	const char *, size_t);
	202	#else
	203	static inline int blk_should_fake_timeout(struct request_queue *q)
	204	{
	205	return 0;
	206	}
	207	#endif
	208
d6d48196 JA	209	int ll_back_merge_fn(struct request_queue q, struct request req,
	210	struct bio *bio);
	211	int ll_front_merge_fn(struct request_queue q, struct request req,
	212	struct bio *bio);
b973cb7e JA	213	struct request attempt_back_merge(struct request_queue q, struct request *rq);
b973cb7e JA	214	struct request attempt_front_merge(struct request_queue q, struct request *rq);
5e84ea3a JA	215	int blk_attempt_req_merge(struct request_queue q, struct request rq,
5e84ea3a JA	216	struct request *next);
d6d48196	217	void blk_recalc_rq_segments(struct request *rq);
80a761fd	218	void blk_rq_set_mixed_merge(struct request *rq);
050c8ea8	219	bool blk_rq_merge_ok(struct request rq, struct bio bio);
34fe7c05	220	enum elv_merge blk_try_merge(struct request rq, struct bio bio);
d6d48196	221
8324aa91 JA	222	void blk_queue_congestion_threshold(struct request_queue *q);
8324aa91 JA	223
ff88972c AB	224	int blk_dev_init(void);
ff88972c AB	225
f253b86b	226
8324aa91 JA	227	/*
	228	* Return the threshold (number of used requests) at which the queue is
	229	* considered to be congested. It include a little hysteresis to keep the
	230	* context switch rate down.
	231	*/
	232	static inline int queue_congestion_on_threshold(struct request_queue *q)
	233	{
	234	return q->nr_congestion_on;
	235	}
	236
	237	/*
	238	* The threshold at which a queue is considered to be uncongested
	239	*/
	240	static inline int queue_congestion_off_threshold(struct request_queue *q)
	241	{
	242	return q->nr_congestion_off;
	243	}
	244
e3a2b3f9 JA	245	extern int blk_update_nr_requests(struct request_queue *, unsigned int);
e3a2b3f9 JA	246
c2553b58 JA	247	/*
	248	* Contribute to IO statistics IFF:
	249	*
	250	* a) it's attached to a gendisk, and
	251	* b) the queue had IO stats enabled when this request was started, and
e2a60da7	252	* c) it's a file system request
c2553b58	253	*/
26308eab	254	static inline int blk_do_io_stat(struct request *rq)
fb8ec18c	255	{
33659ebb	256	return rq->rq_disk &&
e8064021	257	(rq->rq_flags & RQF_IO_STAT) &&
57292b58	258	!blk_rq_is_passthrough(rq);
fb8ec18c JA	259	}
fb8ec18c JA	260
6cf7677f CH	261	static inline void req_set_nomerge(struct request_queue q, struct request req)
	262	{
	263	req->cmd_flags \|= REQ_NOMERGE;
	264	if (req == q->last_merge)
	265	q->last_merge = NULL;
	266	}
	267
f2dbd76a TH	268	/*
	269	* Internal io_context interface
	270	*/
	271	void get_io_context(struct io_context *ioc);
47fdd4ca	272	struct io_cq ioc_lookup_icq(struct io_context ioc, struct request_queue *q);
24acfc34 TH	273	struct io_cq ioc_create_icq(struct io_context ioc, struct request_queue *q,
24acfc34 TH	274	gfp_t gfp_mask);
7e5a8794	275	void ioc_clear_queue(struct request_queue *q);
f2dbd76a	276
24acfc34	277	int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
f2dbd76a	278
c23ecb42 JA	279	/**
	280	* rq_ioc - determine io_context for request allocation
	281	* @bio: request being allocated is for this bio (can be %NULL)
	282	*
	283	* Determine io_context to use for request allocation for @bio. May return
	284	* %NULL if %current->io_context doesn't exist.
	285	*/
	286	static inline struct io_context rq_ioc(struct bio bio)
	287	{
	288	#ifdef CONFIG_BLK_CGROUP
	289	if (bio && bio->bi_ioc)
	290	return bio->bi_ioc;
	291	#endif
	292	return current->io_context;
	293	}
	294
f2dbd76a TH	295	/**
f2dbd76a TH	296	* create_io_context - try to create task->io_context
f2dbd76a TH	297	* @gfp_mask: allocation mask
	298	* @node: allocation node
	299	*
24acfc34 TH	300	* If %current->io_context is %NULL, allocate a new io_context and install
	301	* it. Returns the current %current->io_context which may be %NULL if
	302	* allocation failed.
f2dbd76a TH	303	*
f2dbd76a TH	304	* Note that this function can't be called with IRQ disabled because
24acfc34	305	* task_lock which protects %current->io_context is IRQ-unsafe.
f2dbd76a	306	*/
24acfc34	307	static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
f2dbd76a TH	308	{
f2dbd76a TH	309	WARN_ON_ONCE(irqs_disabled());
24acfc34 TH	310	if (unlikely(!current->io_context))
	311	create_task_io_context(current, gfp_mask, node);
	312	return current->io_context;
f2dbd76a TH	313	}
	314
	315	/*
	316	* Internal throttling interface
	317	*/
bc9fcbf9	318	#ifdef CONFIG_BLK_DEV_THROTTLING
c9a929dd	319	extern void blk_throtl_drain(struct request_queue *q);
bc9fcbf9 TH	320	extern int blk_throtl_init(struct request_queue *q);
	321	extern void blk_throtl_exit(struct request_queue *q);
	322	#else /* CONFIG_BLK_DEV_THROTTLING */
c9a929dd	323	static inline void blk_throtl_drain(struct request_queue *q) { }
bc9fcbf9 TH	324	static inline int blk_throtl_init(struct request_queue *q) { return 0; }
	325	static inline void blk_throtl_exit(struct request_queue *q) { }
	326	#endif /* CONFIG_BLK_DEV_THROTTLING */
297e3d85 SL	327	#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
	328	extern ssize_t blk_throtl_sample_time_show(struct request_queue q, char page);
	329	extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
	330	const char *page, size_t count);
	331	#endif
bc9fcbf9 TH	332
bc9fcbf9 TH	333	#endif /* BLK_INTERNAL_H */