[net-next-2.6.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 int (elevator_queue_empty_fn) (struct request_queue *);
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_queue_empty_fn *elevator_queue_empty_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;
};

/*
 * 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, int);
extern void __elv_add_request(struct request_queue *, struct request *, int, int);
extern void elv_insert(struct request_queue *, struct request *, int);
extern int elv_merge(struct request_queue *, 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 int elv_queue_empty(struct request_queue *);
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 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 struct request *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

/*
 * 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)				\
	do {							\
		preempt_disable();				\
		__get_cpu_var(name) += (__val);			\
		preempt_enable();				\
	} while (0)

#define elv_ioc_count_inc(name)	elv_ioc_count_mod(name, 1)
#define elv_ioc_count_dec(name)	elv_ioc_count_mod(name, -1)

#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 JA	22	typedef void (elevator_add_req_fn) (struct request_queue , struct request );
	23	typedef int (elevator_queue_empty_fn) (struct request_queue *);
	24	typedef struct request (elevator_request_list_fn) (struct request_queue , struct request *);
	25	typedef void (elevator_completed_req_fn) (struct request_queue , struct request );
	26	typedef int (elevator_may_queue_fn) (struct request_queue *, int);
1da177e4	27
165125e1	28	typedef int (elevator_set_req_fn) (struct request_queue , struct request , gfp_t);
bb37b94c	29	typedef void (elevator_put_req_fn) (struct request *);
165125e1 JA	30	typedef void (elevator_activate_req_fn) (struct request_queue , struct request );
165125e1 JA	31	typedef void (elevator_deactivate_req_fn) (struct request_queue , struct request );
1da177e4	32
165125e1	33	typedef void (elevator_init_fn) (struct request_queue );
b374d18a	34	typedef void (elevator_exit_fn) (struct elevator_queue *);
1da177e4 LT	35
	36	struct elevator_ops
	37	{
	38	elevator_merge_fn *elevator_merge_fn;
	39	elevator_merged_fn *elevator_merged_fn;
	40	elevator_merge_req_fn *elevator_merge_req_fn;
da775265	41	elevator_allow_merge_fn *elevator_allow_merge_fn;
812d4026	42	elevator_bio_merged_fn *elevator_bio_merged_fn;
1da177e4	43
8922e16c	44	elevator_dispatch_fn *elevator_dispatch_fn;
1da177e4	45	elevator_add_req_fn *elevator_add_req_fn;
8922e16c	46	elevator_activate_req_fn *elevator_activate_req_fn;
1da177e4 LT	47	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
	48
	49	elevator_queue_empty_fn *elevator_queue_empty_fn;
	50	elevator_completed_req_fn *elevator_completed_req_fn;
	51
	52	elevator_request_list_fn *elevator_former_req_fn;
	53	elevator_request_list_fn *elevator_latter_req_fn;
	54
	55	elevator_set_req_fn *elevator_set_req_fn;
	56	elevator_put_req_fn *elevator_put_req_fn;
	57
	58	elevator_may_queue_fn *elevator_may_queue_fn;
	59
	60	elevator_init_fn *elevator_init_fn;
	61	elevator_exit_fn *elevator_exit_fn;
e17a9489	62	void (trim)(struct io_context );
1da177e4 LT	63	};
	64
	65	#define ELV_NAME_MAX (16)
	66
e572ec7e AV	67	struct elv_fs_entry {
e572ec7e AV	68	struct attribute attr;
b374d18a JA	69	ssize_t (show)(struct elevator_queue , char *);
b374d18a JA	70	ssize_t (store)(struct elevator_queue , const char *, size_t);
e572ec7e AV	71	};
e572ec7e AV	72
1da177e4 LT	73	/*
	74	* identifies an elevator type, such as AS or deadline
	75	*/
	76	struct elevator_type
	77	{
	78	struct list_head list;
	79	struct elevator_ops ops;
e572ec7e	80	struct elv_fs_entry *elevator_attrs;
1da177e4 LT	81	char elevator_name[ELV_NAME_MAX];
	82	struct module *elevator_owner;
	83	};
	84
	85	/*
54069588	86	* each queue has an elevator_queue associated with it
1da177e4 LT	87	*/
	88	struct elevator_queue
	89	{
	90	struct elevator_ops *ops;
	91	void *elevator_data;
	92	struct kobject kobj;
	93	struct elevator_type *elevator_type;
3d1ab40f	94	struct mutex sysfs_lock;
9817064b	95	struct hlist_head *hash;
1da177e4 LT	96	};
	97
	98	/*
	99	* block elevator interface
	100	*/
165125e1 JA	101	extern void elv_dispatch_sort(struct request_queue , struct request );
	102	extern void elv_dispatch_add_tail(struct request_queue , struct request );
	103	extern void elv_add_request(struct request_queue , struct request , int, int);
	104	extern void __elv_add_request(struct request_queue , struct request , int, int);
	105	extern void elv_insert(struct request_queue , struct request , int);
	106	extern int elv_merge(struct request_queue , struct request , struct bio );
	107	extern void elv_merge_requests(struct request_queue , struct request ,
1da177e4	108	struct request *);
165125e1	109	extern void elv_merged_request(struct request_queue , struct request , int);
812d4026 DS	110	extern void elv_bio_merged(struct request_queue q, struct request ,
812d4026 DS	111	struct bio *);
165125e1 JA	112	extern void elv_requeue_request(struct request_queue , struct request );
165125e1 JA	113	extern int elv_queue_empty(struct request_queue *);
165125e1 JA	114	extern struct request elv_former_request(struct request_queue , struct request *);
	115	extern struct request elv_latter_request(struct request_queue , struct request *);
	116	extern int elv_register_queue(struct request_queue *q);
	117	extern void elv_unregister_queue(struct request_queue *q);
	118	extern int elv_may_queue(struct request_queue *, int);
11914a53	119	extern void elv_abort_queue(struct request_queue *);
165125e1 JA	120	extern void elv_completed_request(struct request_queue , struct request );
	121	extern int elv_set_request(struct request_queue , struct request , gfp_t);
	122	extern void elv_put_request(struct request_queue , struct request );
26308eab	123	extern void elv_drain_elevator(struct request_queue *);
1da177e4 LT	124
	125	/*
	126	* io scheduler registration
	127	*/
2fdd82bd	128	extern void elv_register(struct elevator_type *);
1da177e4 LT	129	extern void elv_unregister(struct elevator_type *);
	130
	131	/*
	132	* io scheduler sysfs switching
	133	*/
165125e1 JA	134	extern ssize_t elv_iosched_show(struct request_queue , char );
165125e1 JA	135	extern ssize_t elv_iosched_store(struct request_queue , const char , size_t);
1da177e4	136
165125e1	137	extern int elevator_init(struct request_queue , char );
b374d18a	138	extern void elevator_exit(struct elevator_queue *);
1da177e4	139	extern int elv_rq_merge_ok(struct request , struct bio );
1da177e4	140
2e662b65 JA	141	/*
	142	* Helper functions.
	143	*/
165125e1 JA	144	extern struct request elv_rb_former_request(struct request_queue , struct request *);
165125e1 JA	145	extern struct request elv_rb_latter_request(struct request_queue , struct request *);
2e662b65 JA	146
	147	/*
	148	* rb support functions.
	149	*/
	150	extern struct request elv_rb_add(struct rb_root , struct request *);
	151	extern void elv_rb_del(struct rb_root , struct request );
	152	extern struct request elv_rb_find(struct rb_root , sector_t);
	153
1da177e4 LT	154	/*
	155	* Return values from elevator merger
	156	*/
	157	#define ELEVATOR_NO_MERGE 0
	158	#define ELEVATOR_FRONT_MERGE 1
	159	#define ELEVATOR_BACK_MERGE 2
	160
	161	/*
	162	* Insertion selection
	163	*/
	164	#define ELEVATOR_INSERT_FRONT 1
	165	#define ELEVATOR_INSERT_BACK 2
	166	#define ELEVATOR_INSERT_SORT 3
797e7dbb	167	#define ELEVATOR_INSERT_REQUEUE 4
1da177e4 LT	168
	169	/*
	170	* return values from elevator_may_queue_fn
	171	*/
	172	enum {
	173	ELV_MQUEUE_MAY,
	174	ELV_MQUEUE_NO,
	175	ELV_MQUEUE_MUST,
	176	};
	177
2e46e8b2	178	#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
2e662b65	179	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	180
1fbfdfcd	181	/*
c7c22e4d	182	* Hack to reuse the csd.list list_head as the fifo time holder while
1fbfdfcd JA	183	* the request is in the io scheduler. Saves an unsigned long in rq.
1fbfdfcd JA	184	*/
c7c22e4d JA	185	#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
c7c22e4d JA	186	#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
1fbfdfcd JA	187	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
	188	#define rq_fifo_clear(rq) do { \
	189	list_del_init(&(rq)->queuelist); \
c7c22e4d	190	INIT_LIST_HEAD(&(rq)->csd.list); \
1fbfdfcd JA	191	} while (0)
1fbfdfcd JA	192
4a893e83 JA	193	/*
	194	* io context count accounting
	195	*/
	196	#define elv_ioc_count_mod(name, __val) \
	197	do { \
	198	preempt_disable(); \
	199	__get_cpu_var(name) += (__val); \
	200	preempt_enable(); \
	201	} while (0)
	202
	203	#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
	204	#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
	205
	206	#define elv_ioc_count_read(name) \
	207	({ \
	208	unsigned long __val = 0; \
	209	int __cpu; \
	210	smp_wmb(); \
	211	for_each_possible_cpu(__cpu) \
	212	__val += per_cpu(name, __cpu); \
	213	__val; \
	214	})
	215
9361401e	216	#endif /* CONFIG_BLOCK */
1da177e4	217	#endif