[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 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;

	/*
	 * Used for both plugged list and elevator merging and in the
	 * former case called without queue_lock.  Read comment on top of
	 * attempt_plug_merge() for details.
	 */
	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;
};

#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
{
	/* managed by elevator core */
	struct kmem_cache *icq_cache;

	/* fields provided by elevator implementation */
	struct elevator_ops ops;
	size_t icq_size;
	size_t icq_align;
	struct elv_fs_entry *elevator_attrs;
	char elevator_name[ELV_NAME_MAX];
	struct module *elevator_owner;

	/* managed by elevator core */
	char icq_cache_name[ELV_NAME_MAX + 5];	/* elvname + "_io_cq" */
	struct list_head list;
};

/*
 * each queue has an elevator_queue associated with it
 */
struct elevator_queue
{
	struct elevator_type *type;
	void *elevator_data;
	struct kobject kobj;
	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 int 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)

#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;
bd87b589 TH	41
	42	/*
	43	* Used for both plugged list and elevator merging and in the
	44	* former case called without queue_lock. Read comment on top of
	45	* attempt_plug_merge() for details.
	46	*/
812d4026	47	elevator_bio_merged_fn *elevator_bio_merged_fn;
1da177e4	48
8922e16c	49	elevator_dispatch_fn *elevator_dispatch_fn;
1da177e4	50	elevator_add_req_fn *elevator_add_req_fn;
8922e16c	51	elevator_activate_req_fn *elevator_activate_req_fn;
1da177e4 LT	52	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
1da177e4 LT	53
1da177e4 LT	54	elevator_completed_req_fn *elevator_completed_req_fn;
	55
	56	elevator_request_list_fn *elevator_former_req_fn;
	57	elevator_request_list_fn *elevator_latter_req_fn;
	58
	59	elevator_set_req_fn *elevator_set_req_fn;
	60	elevator_put_req_fn *elevator_put_req_fn;
	61
	62	elevator_may_queue_fn *elevator_may_queue_fn;
	63
	64	elevator_init_fn *elevator_init_fn;
	65	elevator_exit_fn *elevator_exit_fn;
	66	};
	67
	68	#define ELV_NAME_MAX (16)
	69
e572ec7e AV	70	struct elv_fs_entry {
e572ec7e AV	71	struct attribute attr;
b374d18a JA	72	ssize_t (show)(struct elevator_queue , char *);
b374d18a JA	73	ssize_t (store)(struct elevator_queue , const char *, size_t);
e572ec7e AV	74	};
e572ec7e AV	75
1da177e4 LT	76	/*
	77	* identifies an elevator type, such as AS or deadline
	78	*/
	79	struct elevator_type
	80	{
3d3c2379 TH	81	/* managed by elevator core */
	82	struct kmem_cache *icq_cache;
	83
	84	/* fields provided by elevator implementation */
1da177e4	85	struct elevator_ops ops;
3d3c2379 TH	86	size_t icq_size;
3d3c2379 TH	87	size_t icq_align;
e572ec7e	88	struct elv_fs_entry *elevator_attrs;
1da177e4 LT	89	char elevator_name[ELV_NAME_MAX];
1da177e4 LT	90	struct module *elevator_owner;
3d3c2379 TH	91
	92	/* managed by elevator core */
	93	char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
22f746e2	94	struct list_head list;
1da177e4 LT	95	};
	96
	97	/*
54069588	98	* each queue has an elevator_queue associated with it
1da177e4 LT	99	*/
	100	struct elevator_queue
	101	{
22f746e2	102	struct elevator_type *type;
1da177e4 LT	103	void *elevator_data;
1da177e4 LT	104	struct kobject kobj;
3d1ab40f	105	struct mutex sysfs_lock;
9817064b	106	struct hlist_head *hash;
430c62fb	107	unsigned int registered:1;
1da177e4 LT	108	};
	109
	110	/*
	111	* block elevator interface
	112	*/
165125e1 JA	113	extern void elv_dispatch_sort(struct request_queue , struct request );
165125e1 JA	114	extern void elv_dispatch_add_tail(struct request_queue , struct request );
7eaceacc JA	115	extern void elv_add_request(struct request_queue , struct request , int);
7eaceacc JA	116	extern void __elv_add_request(struct request_queue , struct request , int);
165125e1	117	extern int elv_merge(struct request_queue , struct request , struct bio );
73c10101	118	extern int elv_try_merge(struct request , struct bio );
165125e1	119	extern void elv_merge_requests(struct request_queue , struct request ,
1da177e4	120	struct request *);
165125e1	121	extern void elv_merged_request(struct request_queue , struct request , int);
812d4026 DS	122	extern void elv_bio_merged(struct request_queue q, struct request ,
812d4026 DS	123	struct bio *);
165125e1	124	extern void elv_requeue_request(struct request_queue , struct request );
165125e1 JA	125	extern struct request elv_former_request(struct request_queue , struct request *);
	126	extern struct request elv_latter_request(struct request_queue , struct request *);
	127	extern int elv_register_queue(struct request_queue *q);
	128	extern void elv_unregister_queue(struct request_queue *q);
	129	extern int elv_may_queue(struct request_queue *, int);
11914a53	130	extern void elv_abort_queue(struct request_queue *);
165125e1 JA	131	extern void elv_completed_request(struct request_queue , struct request );
	132	extern int elv_set_request(struct request_queue , struct request , gfp_t);
	133	extern void elv_put_request(struct request_queue , struct request );
26308eab	134	extern void elv_drain_elevator(struct request_queue *);
1da177e4 LT	135
	136	/*
	137	* io scheduler registration
	138	*/
3d3c2379	139	extern int elv_register(struct elevator_type *);
1da177e4 LT	140	extern void elv_unregister(struct elevator_type *);
	141
	142	/*
	143	* io scheduler sysfs switching
	144	*/
165125e1 JA	145	extern ssize_t elv_iosched_show(struct request_queue , char );
165125e1 JA	146	extern ssize_t elv_iosched_store(struct request_queue , const char , size_t);
1da177e4	147
165125e1	148	extern int elevator_init(struct request_queue , char );
b374d18a	149	extern void elevator_exit(struct elevator_queue *);
5dd531a0	150	extern int elevator_change(struct request_queue , const char );
1da177e4	151	extern int elv_rq_merge_ok(struct request , struct bio );
1da177e4	152
2e662b65 JA	153	/*
	154	* Helper functions.
	155	*/
165125e1 JA	156	extern struct request elv_rb_former_request(struct request_queue , struct request *);
165125e1 JA	157	extern struct request elv_rb_latter_request(struct request_queue , struct request *);
2e662b65 JA	158
	159	/*
	160	* rb support functions.
	161	*/
796d5116	162	extern void elv_rb_add(struct rb_root , struct request );
2e662b65 JA	163	extern void elv_rb_del(struct rb_root , struct request );
	164	extern struct request elv_rb_find(struct rb_root , sector_t);
	165
1da177e4 LT	166	/*
	167	* Return values from elevator merger
	168	*/
	169	#define ELEVATOR_NO_MERGE 0
	170	#define ELEVATOR_FRONT_MERGE 1
	171	#define ELEVATOR_BACK_MERGE 2
	172
	173	/*
	174	* Insertion selection
	175	*/
	176	#define ELEVATOR_INSERT_FRONT 1
	177	#define ELEVATOR_INSERT_BACK 2
	178	#define ELEVATOR_INSERT_SORT 3
797e7dbb	179	#define ELEVATOR_INSERT_REQUEUE 4
ae1b1539	180	#define ELEVATOR_INSERT_FLUSH 5
5e84ea3a	181	#define ELEVATOR_INSERT_SORT_MERGE 6
1da177e4 LT	182
	183	/*
	184	* return values from elevator_may_queue_fn
	185	*/
	186	enum {
	187	ELV_MQUEUE_MAY,
	188	ELV_MQUEUE_NO,
	189	ELV_MQUEUE_MUST,
	190	};
	191
2e46e8b2	192	#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
2e662b65	193	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	194
1fbfdfcd	195	/*
c7c22e4d	196	* Hack to reuse the csd.list list_head as the fifo time holder while
1fbfdfcd JA	197	* the request is in the io scheduler. Saves an unsigned long in rq.
1fbfdfcd JA	198	*/
c7c22e4d JA	199	#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
c7c22e4d JA	200	#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
1fbfdfcd JA	201	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
	202	#define rq_fifo_clear(rq) do { \
	203	list_del_init(&(rq)->queuelist); \
c7c22e4d	204	INIT_LIST_HEAD(&(rq)->csd.list); \
1fbfdfcd JA	205	} while (0)
1fbfdfcd JA	206
9361401e	207	#endif /* CONFIG_BLOCK */
1da177e4	208	#endif