[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) (request_queue_t *, struct request **,
				 struct bio *);

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

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

typedef int (elevator_dispatch_fn) (request_queue_t *, int);

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

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

typedef void *(elevator_init_fn) (request_queue_t *);
typedef void (elevator_exit_fn) (elevator_t *);

struct elevator_ops
{
	elevator_merge_fn *elevator_merge_fn;
	elevator_merged_fn *elevator_merged_fn;
	elevator_merge_req_fn *elevator_merge_req_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)(elevator_t *, char *);
	ssize_t (*store)(elevator_t *, 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(request_queue_t *, struct request *);
extern void elv_dispatch_add_tail(request_queue_t *, struct request *);
extern void elv_add_request(request_queue_t *, struct request *, int, int);
extern void __elv_add_request(request_queue_t *, struct request *, int, int);
extern void elv_insert(request_queue_t *, struct request *, int);
extern int elv_merge(request_queue_t *, struct request **, struct bio *);
extern void elv_merge_requests(request_queue_t *, struct request *,
			       struct request *);
extern void elv_merged_request(request_queue_t *, struct request *, int);
extern void elv_dequeue_request(request_queue_t *, struct request *);
extern void elv_requeue_request(request_queue_t *, struct request *);
extern int elv_queue_empty(request_queue_t *);
extern struct request *elv_next_request(struct request_queue *q);
extern struct request *elv_former_request(request_queue_t *, struct request *);
extern struct request *elv_latter_request(request_queue_t *, struct request *);
extern int elv_register_queue(request_queue_t *q);
extern void elv_unregister_queue(request_queue_t *q);
extern int elv_may_queue(request_queue_t *, int);
extern void elv_completed_request(request_queue_t *, struct request *);
extern int elv_set_request(request_queue_t *, struct request *, gfp_t);
extern void elv_put_request(request_queue_t *, struct request *);

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

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

extern int elevator_init(request_queue_t *, char *);
extern void elevator_exit(elevator_t *);
extern int elv_rq_merge_ok(struct request *, struct bio *);

/*
 * Helper functions.
 */
extern struct request *elv_rb_former_request(request_queue_t *, struct request *);
extern struct request *elv_rb_latter_request(request_queue_t *, 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 donelist 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)->donelist.next)
#define rq_set_fifo_time(rq,exp)	((rq)->donelist.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)->donelist);	\
	} 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
1da177e4 LT	8	typedef int (elevator_merge_fn) (request_queue_t , struct request *,
	9	struct bio *);
	10
	11	typedef void (elevator_merge_req_fn) (request_queue_t , struct request , struct request *);
	12
2e662b65	13	typedef void (elevator_merged_fn) (request_queue_t , struct request , int);
1da177e4	14
8922e16c	15	typedef int (elevator_dispatch_fn) (request_queue_t *, int);
1da177e4	16
8922e16c	17	typedef void (elevator_add_req_fn) (request_queue_t , struct request );
1da177e4	18	typedef int (elevator_queue_empty_fn) (request_queue_t *);
1da177e4 LT	19	typedef struct request (elevator_request_list_fn) (request_queue_t , struct request *);
1da177e4 LT	20	typedef void (elevator_completed_req_fn) (request_queue_t , struct request );
cb78b285	21	typedef int (elevator_may_queue_fn) (request_queue_t *, int);
1da177e4	22
cb78b285	23	typedef int (elevator_set_req_fn) (request_queue_t , struct request , gfp_t);
bb37b94c	24	typedef void (elevator_put_req_fn) (struct request *);
8922e16c	25	typedef void (elevator_activate_req_fn) (request_queue_t , struct request );
1da177e4 LT	26	typedef void (elevator_deactivate_req_fn) (request_queue_t , struct request );
1da177e4 LT	27
bb37b94c	28	typedef void (elevator_init_fn) (request_queue_t );
1da177e4 LT	29	typedef void (elevator_exit_fn) (elevator_t *);
	30
	31	struct elevator_ops
	32	{
	33	elevator_merge_fn *elevator_merge_fn;
	34	elevator_merged_fn *elevator_merged_fn;
	35	elevator_merge_req_fn *elevator_merge_req_fn;
	36
8922e16c	37	elevator_dispatch_fn *elevator_dispatch_fn;
1da177e4	38	elevator_add_req_fn *elevator_add_req_fn;
8922e16c	39	elevator_activate_req_fn *elevator_activate_req_fn;
1da177e4 LT	40	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
	41
	42	elevator_queue_empty_fn *elevator_queue_empty_fn;
	43	elevator_completed_req_fn *elevator_completed_req_fn;
	44
	45	elevator_request_list_fn *elevator_former_req_fn;
	46	elevator_request_list_fn *elevator_latter_req_fn;
	47
	48	elevator_set_req_fn *elevator_set_req_fn;
	49	elevator_put_req_fn *elevator_put_req_fn;
	50
	51	elevator_may_queue_fn *elevator_may_queue_fn;
	52
	53	elevator_init_fn *elevator_init_fn;
	54	elevator_exit_fn *elevator_exit_fn;
e17a9489	55	void (trim)(struct io_context );
1da177e4 LT	56	};
	57
	58	#define ELV_NAME_MAX (16)
	59
e572ec7e AV	60	struct elv_fs_entry {
	61	struct attribute attr;
	62	ssize_t (show)(elevator_t , char *);
	63	ssize_t (store)(elevator_t , const char *, size_t);
	64	};
	65
1da177e4 LT	66	/*
	67	* identifies an elevator type, such as AS or deadline
	68	*/
	69	struct elevator_type
	70	{
	71	struct list_head list;
	72	struct elevator_ops ops;
e572ec7e	73	struct elv_fs_entry *elevator_attrs;
1da177e4 LT	74	char elevator_name[ELV_NAME_MAX];
	75	struct module *elevator_owner;
	76	};
	77
	78	/*
54069588	79	* each queue has an elevator_queue associated with it
1da177e4 LT	80	*/
	81	struct elevator_queue
	82	{
	83	struct elevator_ops *ops;
	84	void *elevator_data;
	85	struct kobject kobj;
	86	struct elevator_type *elevator_type;
3d1ab40f	87	struct mutex sysfs_lock;
9817064b	88	struct hlist_head *hash;
1da177e4 LT	89	};
	90
	91	/*
	92	* block elevator interface
	93	*/
1b47f531	94	extern void elv_dispatch_sort(request_queue_t , struct request );
9817064b	95	extern void elv_dispatch_add_tail(request_queue_t , struct request );
1da177e4 LT	96	extern void elv_add_request(request_queue_t , struct request , int, int);
1da177e4 LT	97	extern void __elv_add_request(request_queue_t , struct request , int, int);
30e9656c	98	extern void elv_insert(request_queue_t , struct request , int);
1da177e4 LT	99	extern int elv_merge(request_queue_t , struct request , struct bio );
	100	extern void elv_merge_requests(request_queue_t , struct request ,
	101	struct request *);
2e662b65	102	extern void elv_merged_request(request_queue_t , struct request , int);
8922e16c	103	extern void elv_dequeue_request(request_queue_t , struct request );
1da177e4	104	extern void elv_requeue_request(request_queue_t , struct request );
1da177e4 LT	105	extern int elv_queue_empty(request_queue_t *);
	106	extern struct request elv_next_request(struct request_queue q);
	107	extern struct request elv_former_request(request_queue_t , struct request *);
	108	extern struct request elv_latter_request(request_queue_t , struct request *);
	109	extern int elv_register_queue(request_queue_t *q);
	110	extern void elv_unregister_queue(request_queue_t *q);
cb78b285	111	extern int elv_may_queue(request_queue_t *, int);
1da177e4	112	extern void elv_completed_request(request_queue_t , struct request );
cb78b285	113	extern int elv_set_request(request_queue_t , struct request , gfp_t);
1da177e4 LT	114	extern void elv_put_request(request_queue_t , struct request );
	115
	116	/*
	117	* io scheduler registration
	118	*/
	119	extern int elv_register(struct elevator_type *);
	120	extern void elv_unregister(struct elevator_type *);
	121
	122	/*
	123	* io scheduler sysfs switching
	124	*/
	125	extern ssize_t elv_iosched_show(request_queue_t , char );
	126	extern ssize_t elv_iosched_store(request_queue_t , const char , size_t);
	127
	128	extern int elevator_init(request_queue_t , char );
	129	extern void elevator_exit(elevator_t *);
	130	extern int elv_rq_merge_ok(struct request , struct bio );
1da177e4	131
2e662b65 JA	132	/*
	133	* Helper functions.
	134	*/
	135	extern struct request elv_rb_former_request(request_queue_t , struct request *);
	136	extern struct request elv_rb_latter_request(request_queue_t , struct request *);
	137
	138	/*
	139	* rb support functions.
	140	*/
	141	extern struct request elv_rb_add(struct rb_root , struct request *);
	142	extern void elv_rb_del(struct rb_root , struct request );
	143	extern struct request elv_rb_find(struct rb_root , sector_t);
	144
1da177e4 LT	145	/*
	146	* Return values from elevator merger
	147	*/
	148	#define ELEVATOR_NO_MERGE 0
	149	#define ELEVATOR_FRONT_MERGE 1
	150	#define ELEVATOR_BACK_MERGE 2
	151
	152	/*
	153	* Insertion selection
	154	*/
	155	#define ELEVATOR_INSERT_FRONT 1
	156	#define ELEVATOR_INSERT_BACK 2
	157	#define ELEVATOR_INSERT_SORT 3
797e7dbb	158	#define ELEVATOR_INSERT_REQUEUE 4
1da177e4 LT	159
	160	/*
	161	* return values from elevator_may_queue_fn
	162	*/
	163	enum {
	164	ELV_MQUEUE_MAY,
	165	ELV_MQUEUE_NO,
	166	ELV_MQUEUE_MUST,
	167	};
	168
1b47f531	169	#define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
2e662b65	170	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	171
1fbfdfcd JA	172	/*
	173	* Hack to reuse the donelist list_head as the fifo time holder while
	174	* the request is in the io scheduler. Saves an unsigned long in rq.
	175	*/
	176	#define rq_fifo_time(rq) ((unsigned long) (rq)->donelist.next)
	177	#define rq_set_fifo_time(rq,exp) ((rq)->donelist.next = (void *) (exp))
	178	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
	179	#define rq_fifo_clear(rq) do { \
	180	list_del_init(&(rq)->queuelist); \
	181	INIT_LIST_HEAD(&(rq)->donelist); \
	182	} while (0)
	183
4a893e83 JA	184	/*
	185	* io context count accounting
	186	*/
	187	#define elv_ioc_count_mod(name, __val) \
	188	do { \
	189	preempt_disable(); \
	190	__get_cpu_var(name) += (__val); \
	191	preempt_enable(); \
	192	} while (0)
	193
	194	#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
	195	#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
	196
	197	#define elv_ioc_count_read(name) \
	198	({ \
	199	unsigned long __val = 0; \
	200	int __cpu; \
	201	smp_wmb(); \
	202	for_each_possible_cpu(__cpu) \
	203	__val += per_cpu(name, __cpu); \
	204	__val; \
	205	})
	206
9361401e	207	#endif /* CONFIG_BLOCK */
1da177e4	208	#endif