[linux-block.git] / include / linux / elevator.h

#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H

#include <linux/percpu.h>

#ifdef CONFIG_BLOCK

typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
				 struct bio *);

typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);

typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);

typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);

typedef void (elevator_bio_merged_fn) (struct request_queue *,
						struct request *, struct bio *);

typedef int (elevator_dispatch_fn) (struct request_queue *, int);

typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_may_queue_fn) (struct request_queue *, int);

typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
typedef void (elevator_put_req_fn) (struct request *);
typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);

typedef void *(elevator_init_fn) (struct request_queue *);
typedef void (elevator_exit_fn) (struct elevator_queue *);

struct elevator_ops
{
	elevator_merge_fn *elevator_merge_fn;
	elevator_merged_fn *elevator_merged_fn;
	elevator_merge_req_fn *elevator_merge_req_fn;
	elevator_allow_merge_fn *elevator_allow_merge_fn;
	elevator_bio_merged_fn *elevator_bio_merged_fn;

	elevator_dispatch_fn *elevator_dispatch_fn;
	elevator_add_req_fn *elevator_add_req_fn;
	elevator_activate_req_fn *elevator_activate_req_fn;
	elevator_deactivate_req_fn *elevator_deactivate_req_fn;

	elevator_completed_req_fn *elevator_completed_req_fn;

	elevator_request_list_fn *elevator_former_req_fn;
	elevator_request_list_fn *elevator_latter_req_fn;

	elevator_set_req_fn *elevator_set_req_fn;
	elevator_put_req_fn *elevator_put_req_fn;

	elevator_may_queue_fn *elevator_may_queue_fn;

	elevator_init_fn *elevator_init_fn;
	elevator_exit_fn *elevator_exit_fn;
	void (*trim)(struct io_context *);
};

#define ELV_NAME_MAX	(16)

struct elv_fs_entry {
	struct attribute attr;
	ssize_t (*show)(struct elevator_queue *, char *);
	ssize_t (*store)(struct elevator_queue *, const char *, size_t);
};

/*
 * identifies an elevator type, such as AS or deadline
 */
struct elevator_type
{
	struct list_head list;
	struct elevator_ops ops;
	struct elv_fs_entry *elevator_attrs;
	char elevator_name[ELV_NAME_MAX];
	struct module *elevator_owner;
};

/*
 * each queue has an elevator_queue associated with it
 */
struct elevator_queue
{
	struct elevator_ops *ops;
	void *elevator_data;
	struct kobject kobj;
	struct elevator_type *elevator_type;
	struct mutex sysfs_lock;
	struct hlist_head *hash;
	unsigned int registered:1;
};

/*
 * block elevator interface
 */
extern void elv_dispatch_sort(struct request_queue *, struct request *);
extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
extern void elv_add_request(struct request_queue *, struct request *, int);
extern void __elv_add_request(struct request_queue *, struct request *, int);
extern int elv_merge(struct request_queue *, struct request **, struct bio *);
extern int elv_try_merge(struct request *, struct bio *);
extern void elv_merge_requests(struct request_queue *, struct request *,
			       struct request *);
extern void elv_merged_request(struct request_queue *, struct request *, int);
extern void elv_bio_merged(struct request_queue *q, struct request *,
				struct bio *);
extern void elv_requeue_request(struct request_queue *, struct request *);
extern struct request *elv_former_request(struct request_queue *, struct request *);
extern struct request *elv_latter_request(struct request_queue *, struct request *);
extern int elv_register_queue(struct request_queue *q);
extern void elv_unregister_queue(struct request_queue *q);
extern int elv_may_queue(struct request_queue *, int);
extern void elv_abort_queue(struct request_queue *);
extern void elv_completed_request(struct request_queue *, struct request *);
extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
extern void elv_put_request(struct request_queue *, struct request *);
extern void elv_drain_elevator(struct request_queue *);

/*
 * io scheduler registration
 */
extern void elv_register(struct elevator_type *);
extern void elv_unregister(struct elevator_type *);

/*
 * io scheduler sysfs switching
 */
extern ssize_t elv_iosched_show(struct request_queue *, char *);
extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);

extern int elevator_init(struct request_queue *, char *);
extern void elevator_exit(struct elevator_queue *);
extern int elevator_change(struct request_queue *, const char *);
extern int elv_rq_merge_ok(struct request *, struct bio *);

/*
 * Helper functions.
 */
extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);

/*
 * rb support functions.
 */
extern void elv_rb_add(struct rb_root *, struct request *);
extern void elv_rb_del(struct rb_root *, struct request *);
extern struct request *elv_rb_find(struct rb_root *, sector_t);

/*
 * Return values from elevator merger
 */
#define ELEVATOR_NO_MERGE	0
#define ELEVATOR_FRONT_MERGE	1
#define ELEVATOR_BACK_MERGE	2

/*
 * Insertion selection
 */
#define ELEVATOR_INSERT_FRONT	1
#define ELEVATOR_INSERT_BACK	2
#define ELEVATOR_INSERT_SORT	3
#define ELEVATOR_INSERT_REQUEUE	4
#define ELEVATOR_INSERT_FLUSH	5
#define ELEVATOR_INSERT_SORT_MERGE	6

/*
 * return values from elevator_may_queue_fn
 */
enum {
	ELV_MQUEUE_MAY,
	ELV_MQUEUE_NO,
	ELV_MQUEUE_MUST,
};

#define rq_end_sector(rq)	(blk_rq_pos(rq) + blk_rq_sectors(rq))
#define rb_entry_rq(node)	rb_entry((node), struct request, rb_node)

/*
 * Hack to reuse the csd.list list_head as the fifo time holder while
 * the request is in the io scheduler. Saves an unsigned long in rq.
 */
#define rq_fifo_time(rq)	((unsigned long) (rq)->csd.list.next)
#define rq_set_fifo_time(rq,exp)	((rq)->csd.list.next = (void *) (exp))
#define rq_entry_fifo(ptr)	list_entry((ptr), struct request, queuelist)
#define rq_fifo_clear(rq)	do {		\
	list_del_init(&(rq)->queuelist);	\
	INIT_LIST_HEAD(&(rq)->csd.list);	\
	} while (0)

/*
 * io context count accounting
 */
#define elv_ioc_count_mod(name, __val) this_cpu_add(name, __val)
#define elv_ioc_count_inc(name)	this_cpu_inc(name)
#define elv_ioc_count_dec(name)	this_cpu_dec(name)

#define elv_ioc_count_read(name)				\
({								\
	unsigned long __val = 0;				\
	int __cpu;						\
	smp_wmb();						\
	for_each_possible_cpu(__cpu)				\
		__val += per_cpu(name, __cpu);			\
	__val;							\
})

#endif /* CONFIG_BLOCK */
#endif
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_ELEVATOR_H
	2	#define _LINUX_ELEVATOR_H
	3
4a893e83 JA	4	#include <linux/percpu.h>
4a893e83 JA	5
9361401e DH	6	#ifdef CONFIG_BLOCK
9361401e DH	7
165125e1	8	typedef int (elevator_merge_fn) (struct request_queue , struct request *,
1da177e4 LT	9	struct bio *);
1da177e4 LT	10
165125e1	11	typedef void (elevator_merge_req_fn) (struct request_queue , struct request , struct request *);
1da177e4	12
165125e1	13	typedef void (elevator_merged_fn) (struct request_queue , struct request , int);
1da177e4	14
165125e1	15	typedef int (elevator_allow_merge_fn) (struct request_queue , struct request , struct bio *);
da775265	16
812d4026 DS	17	typedef void (elevator_bio_merged_fn) (struct request_queue *,
	18	struct request , struct bio );
	19
165125e1	20	typedef int (elevator_dispatch_fn) (struct request_queue *, int);
1da177e4	21
165125e1	22	typedef void (elevator_add_req_fn) (struct request_queue , struct request );
165125e1 JA	23	typedef struct request (elevator_request_list_fn) (struct request_queue , struct request *);
	24	typedef void (elevator_completed_req_fn) (struct request_queue , struct request );
	25	typedef int (elevator_may_queue_fn) (struct request_queue *, int);
1da177e4	26
165125e1	27	typedef int (elevator_set_req_fn) (struct request_queue , struct request , gfp_t);
bb37b94c	28	typedef void (elevator_put_req_fn) (struct request *);
165125e1 JA	29	typedef void (elevator_activate_req_fn) (struct request_queue , struct request );
165125e1 JA	30	typedef void (elevator_deactivate_req_fn) (struct request_queue , struct request );
1da177e4	31
165125e1	32	typedef void (elevator_init_fn) (struct request_queue );
b374d18a	33	typedef void (elevator_exit_fn) (struct elevator_queue *);
1da177e4 LT	34
	35	struct elevator_ops
	36	{
	37	elevator_merge_fn *elevator_merge_fn;
	38	elevator_merged_fn *elevator_merged_fn;
	39	elevator_merge_req_fn *elevator_merge_req_fn;
da775265	40	elevator_allow_merge_fn *elevator_allow_merge_fn;
812d4026	41	elevator_bio_merged_fn *elevator_bio_merged_fn;
1da177e4	42
8922e16c	43	elevator_dispatch_fn *elevator_dispatch_fn;
1da177e4	44	elevator_add_req_fn *elevator_add_req_fn;
8922e16c	45	elevator_activate_req_fn *elevator_activate_req_fn;
1da177e4 LT	46	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
1da177e4 LT	47
1da177e4 LT	48	elevator_completed_req_fn *elevator_completed_req_fn;
	49
	50	elevator_request_list_fn *elevator_former_req_fn;
	51	elevator_request_list_fn *elevator_latter_req_fn;
	52
	53	elevator_set_req_fn *elevator_set_req_fn;
	54	elevator_put_req_fn *elevator_put_req_fn;
	55
	56	elevator_may_queue_fn *elevator_may_queue_fn;
	57
	58	elevator_init_fn *elevator_init_fn;
	59	elevator_exit_fn *elevator_exit_fn;
e17a9489	60	void (trim)(struct io_context );
1da177e4 LT	61	};
	62
	63	#define ELV_NAME_MAX (16)
	64
e572ec7e AV	65	struct elv_fs_entry {
e572ec7e AV	66	struct attribute attr;
b374d18a JA	67	ssize_t (show)(struct elevator_queue , char *);
b374d18a JA	68	ssize_t (store)(struct elevator_queue , const char *, size_t);
e572ec7e AV	69	};
e572ec7e AV	70
1da177e4 LT	71	/*
	72	* identifies an elevator type, such as AS or deadline
	73	*/
	74	struct elevator_type
	75	{
	76	struct list_head list;
	77	struct elevator_ops ops;
e572ec7e	78	struct elv_fs_entry *elevator_attrs;
1da177e4 LT	79	char elevator_name[ELV_NAME_MAX];
	80	struct module *elevator_owner;
	81	};
	82
	83	/*
54069588	84	* each queue has an elevator_queue associated with it
1da177e4 LT	85	*/
	86	struct elevator_queue
	87	{
	88	struct elevator_ops *ops;
	89	void *elevator_data;
	90	struct kobject kobj;
	91	struct elevator_type *elevator_type;
3d1ab40f	92	struct mutex sysfs_lock;
9817064b	93	struct hlist_head *hash;
430c62fb	94	unsigned int registered:1;
1da177e4 LT	95	};
	96
	97	/*
	98	* block elevator interface
	99	*/
165125e1 JA	100	extern void elv_dispatch_sort(struct request_queue , struct request );
165125e1 JA	101	extern void elv_dispatch_add_tail(struct request_queue , struct request );
7eaceacc JA	102	extern void elv_add_request(struct request_queue , struct request , int);
7eaceacc JA	103	extern void __elv_add_request(struct request_queue , struct request , int);
165125e1	104	extern int elv_merge(struct request_queue , struct request , struct bio );
73c10101	105	extern int elv_try_merge(struct request , struct bio );
165125e1	106	extern void elv_merge_requests(struct request_queue , struct request ,
1da177e4	107	struct request *);
165125e1	108	extern void elv_merged_request(struct request_queue , struct request , int);
812d4026 DS	109	extern void elv_bio_merged(struct request_queue q, struct request ,
812d4026 DS	110	struct bio *);
165125e1	111	extern void elv_requeue_request(struct request_queue , struct request );
165125e1 JA	112	extern struct request elv_former_request(struct request_queue , struct request *);
	113	extern struct request elv_latter_request(struct request_queue , struct request *);
	114	extern int elv_register_queue(struct request_queue *q);
	115	extern void elv_unregister_queue(struct request_queue *q);
	116	extern int elv_may_queue(struct request_queue *, int);
11914a53	117	extern void elv_abort_queue(struct request_queue *);
165125e1 JA	118	extern void elv_completed_request(struct request_queue , struct request );
	119	extern int elv_set_request(struct request_queue , struct request , gfp_t);
	120	extern void elv_put_request(struct request_queue , struct request );
26308eab	121	extern void elv_drain_elevator(struct request_queue *);
1da177e4 LT	122
	123	/*
	124	* io scheduler registration
	125	*/
2fdd82bd	126	extern void elv_register(struct elevator_type *);
1da177e4 LT	127	extern void elv_unregister(struct elevator_type *);
	128
	129	/*
	130	* io scheduler sysfs switching
	131	*/
165125e1 JA	132	extern ssize_t elv_iosched_show(struct request_queue , char );
165125e1 JA	133	extern ssize_t elv_iosched_store(struct request_queue , const char , size_t);
1da177e4	134
165125e1	135	extern int elevator_init(struct request_queue , char );
b374d18a	136	extern void elevator_exit(struct elevator_queue *);
5dd531a0	137	extern int elevator_change(struct request_queue , const char );
1da177e4	138	extern int elv_rq_merge_ok(struct request , struct bio );
1da177e4	139
2e662b65 JA	140	/*
	141	* Helper functions.
	142	*/
165125e1 JA	143	extern struct request elv_rb_former_request(struct request_queue , struct request *);
165125e1 JA	144	extern struct request elv_rb_latter_request(struct request_queue , struct request *);
2e662b65 JA	145
	146	/*
	147	* rb support functions.
	148	*/
796d5116	149	extern void elv_rb_add(struct rb_root , struct request );
2e662b65 JA	150	extern void elv_rb_del(struct rb_root , struct request );
	151	extern struct request elv_rb_find(struct rb_root , sector_t);
	152
1da177e4 LT	153	/*
	154	* Return values from elevator merger
	155	*/
	156	#define ELEVATOR_NO_MERGE 0
	157	#define ELEVATOR_FRONT_MERGE 1
	158	#define ELEVATOR_BACK_MERGE 2
	159
	160	/*
	161	* Insertion selection
	162	*/
	163	#define ELEVATOR_INSERT_FRONT 1
	164	#define ELEVATOR_INSERT_BACK 2
	165	#define ELEVATOR_INSERT_SORT 3
797e7dbb	166	#define ELEVATOR_INSERT_REQUEUE 4
ae1b1539	167	#define ELEVATOR_INSERT_FLUSH 5
5e84ea3a	168	#define ELEVATOR_INSERT_SORT_MERGE 6
1da177e4 LT	169
	170	/*
	171	* return values from elevator_may_queue_fn
	172	*/
	173	enum {
	174	ELV_MQUEUE_MAY,
	175	ELV_MQUEUE_NO,
	176	ELV_MQUEUE_MUST,
	177	};
	178
2e46e8b2	179	#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
2e662b65	180	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	181
1fbfdfcd	182	/*
c7c22e4d	183	* Hack to reuse the csd.list list_head as the fifo time holder while
1fbfdfcd JA	184	* the request is in the io scheduler. Saves an unsigned long in rq.
1fbfdfcd JA	185	*/
c7c22e4d JA	186	#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
c7c22e4d JA	187	#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
1fbfdfcd JA	188	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
	189	#define rq_fifo_clear(rq) do { \
	190	list_del_init(&(rq)->queuelist); \
c7c22e4d	191	INIT_LIST_HEAD(&(rq)->csd.list); \
1fbfdfcd JA	192	} while (0)
1fbfdfcd JA	193
4a893e83 JA	194	/*
	195	* io context count accounting
	196	*/
909ea964 CL	197	#define elv_ioc_count_mod(name, __val) this_cpu_add(name, __val)
	198	#define elv_ioc_count_inc(name) this_cpu_inc(name)
	199	#define elv_ioc_count_dec(name) this_cpu_dec(name)
4a893e83 JA	200
	201	#define elv_ioc_count_read(name) \
	202	({ \
	203	unsigned long __val = 0; \
	204	int __cpu; \
	205	smp_wmb(); \
	206	for_each_possible_cpu(__cpu) \
	207	__val += per_cpu(name, __cpu); \
	208	__val; \
	209	})
	210
9361401e	211	#endif /* CONFIG_BLOCK */
1da177e4	212	#endif