[linux.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 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_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_dequeue_request(struct request_queue *, struct request *);
extern void elv_requeue_request(struct request_queue *, struct request *);
extern int elv_queue_empty(struct request_queue *);
extern struct request *elv_next_request(struct request_queue *q);
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 *);

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