[linux-2.6-block.git] / include / linux / elevator.h

#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H

#include <linux/percpu.h>
#include <linux/hashtable.h>

#ifdef CONFIG_BLOCK

struct io_cq;
struct elevator_type;

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 void (elevator_init_icq_fn) (struct io_cq *);
typedef void (elevator_exit_icq_fn) (struct io_cq *);
typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
				   struct bio *, 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 int (elevator_init_fn) (struct request_queue *,
				struct elevator_type *e);
typedef void (elevator_exit_fn) (struct elevator_queue *);
typedef void (elevator_registered_fn) (struct request_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_init_icq_fn *elevator_init_icq_fn;	/* see iocontext.h */
	elevator_exit_icq_fn *elevator_exit_icq_fn;	/* ditto */

	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;
	elevator_registered_fn *elevator_registered_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;	/* see iocontext.h */
	size_t icq_align;	/* ditto */
	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;
};

#define ELV_HASH_BITS 6

/*
 * 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;
	unsigned int registered:1;
	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
};

/*
 * 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 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_completed_request(struct request_queue *, struct request *);
extern int elv_set_request(struct request_queue *q, struct request *rq,
			   struct bio *bio, gfp_t gfp_mask);
extern void elv_put_request(struct request_queue *, struct request *);
extern void elv_drain_elevator(struct request_queue *);

/*
 * io scheduler registration
 */
extern void __init load_default_elevator_module(void);
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 bool elv_rq_merge_ok(struct request *, struct bio *);
extern struct elevator_queue *elevator_alloc(struct request_queue *,
					struct elevator_type *);

/*
 * 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)

#define rq_entry_fifo(ptr)	list_entry((ptr), struct request, queuelist)
#define rq_fifo_clear(rq)	list_del_init(&(rq)->queuelist)

#else /* CONFIG_BLOCK */

static inline void load_default_elevator_module(void) { }

#endif /* CONFIG_BLOCK */
#endif
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_ELEVATOR_H
	2	#define _LINUX_ELEVATOR_H
	3
4a893e83	4	#include <linux/percpu.h>
242d98f0	5	#include <linux/hashtable.h>
4a893e83	6
9361401e DH	7	#ifdef CONFIG_BLOCK
9361401e DH	8
7e5a8794	9	struct io_cq;
d50235b7	10	struct elevator_type;
7e5a8794	11
165125e1	12	typedef int (elevator_merge_fn) (struct request_queue , struct request *,
1da177e4 LT	13	struct bio *);
1da177e4 LT	14
165125e1	15	typedef void (elevator_merge_req_fn) (struct request_queue , struct request , struct request *);
1da177e4	16
165125e1	17	typedef void (elevator_merged_fn) (struct request_queue , struct request , int);
1da177e4	18
165125e1	19	typedef int (elevator_allow_merge_fn) (struct request_queue , struct request , struct bio *);
da775265	20
812d4026 DS	21	typedef void (elevator_bio_merged_fn) (struct request_queue *,
	22	struct request , struct bio );
	23
165125e1	24	typedef int (elevator_dispatch_fn) (struct request_queue *, int);
1da177e4	25
165125e1	26	typedef void (elevator_add_req_fn) (struct request_queue , struct request );
165125e1 JA	27	typedef struct request (elevator_request_list_fn) (struct request_queue , struct request *);
	28	typedef void (elevator_completed_req_fn) (struct request_queue , struct request );
	29	typedef int (elevator_may_queue_fn) (struct request_queue *, int);
1da177e4	30
9b84cacd	31	typedef void (elevator_init_icq_fn) (struct io_cq *);
7e5a8794	32	typedef void (elevator_exit_icq_fn) (struct io_cq *);
852c788f TH	33	typedef int (elevator_set_req_fn) (struct request_queue , struct request ,
852c788f TH	34	struct bio *, gfp_t);
bb37b94c	35	typedef void (elevator_put_req_fn) (struct request *);
165125e1 JA	36	typedef void (elevator_activate_req_fn) (struct request_queue , struct request );
165125e1 JA	37	typedef void (elevator_deactivate_req_fn) (struct request_queue , struct request );
1da177e4	38
d50235b7 JM	39	typedef int (elevator_init_fn) (struct request_queue *,
d50235b7 JM	40	struct elevator_type *e);
b374d18a	41	typedef void (elevator_exit_fn) (struct elevator_queue *);
0bb97947	42	typedef void (elevator_registered_fn) (struct request_queue *);
1da177e4 LT	43
	44	struct elevator_ops
	45	{
	46	elevator_merge_fn *elevator_merge_fn;
	47	elevator_merged_fn *elevator_merged_fn;
	48	elevator_merge_req_fn *elevator_merge_req_fn;
da775265	49	elevator_allow_merge_fn *elevator_allow_merge_fn;
812d4026	50	elevator_bio_merged_fn *elevator_bio_merged_fn;
1da177e4	51
8922e16c	52	elevator_dispatch_fn *elevator_dispatch_fn;
1da177e4	53	elevator_add_req_fn *elevator_add_req_fn;
8922e16c	54	elevator_activate_req_fn *elevator_activate_req_fn;
1da177e4 LT	55	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
1da177e4 LT	56
1da177e4 LT	57	elevator_completed_req_fn *elevator_completed_req_fn;
	58
	59	elevator_request_list_fn *elevator_former_req_fn;
	60	elevator_request_list_fn *elevator_latter_req_fn;
	61
f1f8cc94 TH	62	elevator_init_icq_fn elevator_init_icq_fn; / see iocontext.h */
f1f8cc94 TH	63	elevator_exit_icq_fn elevator_exit_icq_fn; / ditto */
7e5a8794	64
1da177e4 LT	65	elevator_set_req_fn *elevator_set_req_fn;
	66	elevator_put_req_fn *elevator_put_req_fn;
	67
	68	elevator_may_queue_fn *elevator_may_queue_fn;
	69
	70	elevator_init_fn *elevator_init_fn;
	71	elevator_exit_fn *elevator_exit_fn;
0bb97947	72	elevator_registered_fn *elevator_registered_fn;
1da177e4 LT	73	};
	74
	75	#define ELV_NAME_MAX (16)
	76
e572ec7e AV	77	struct elv_fs_entry {
e572ec7e AV	78	struct attribute attr;
b374d18a JA	79	ssize_t (show)(struct elevator_queue , char *);
b374d18a JA	80	ssize_t (store)(struct elevator_queue , const char *, size_t);
e572ec7e AV	81	};
e572ec7e AV	82
1da177e4 LT	83	/*
	84	* identifies an elevator type, such as AS or deadline
	85	*/
	86	struct elevator_type
	87	{
3d3c2379 TH	88	/* managed by elevator core */
	89	struct kmem_cache *icq_cache;
	90
	91	/* fields provided by elevator implementation */
1da177e4	92	struct elevator_ops ops;
f1f8cc94 TH	93	size_t icq_size; /* see iocontext.h */
f1f8cc94 TH	94	size_t icq_align; /* ditto */
e572ec7e	95	struct elv_fs_entry *elevator_attrs;
1da177e4 LT	96	char elevator_name[ELV_NAME_MAX];
1da177e4 LT	97	struct module *elevator_owner;
3d3c2379 TH	98
	99	/* managed by elevator core */
	100	char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
22f746e2	101	struct list_head list;
1da177e4 LT	102	};
1da177e4 LT	103
242d98f0 SL	104	#define ELV_HASH_BITS 6
242d98f0 SL	105
1da177e4	106	/*
54069588	107	* each queue has an elevator_queue associated with it
1da177e4 LT	108	*/
	109	struct elevator_queue
	110	{
22f746e2	111	struct elevator_type *type;
1da177e4 LT	112	void *elevator_data;
1da177e4 LT	113	struct kobject kobj;
3d1ab40f	114	struct mutex sysfs_lock;
430c62fb	115	unsigned int registered:1;
242d98f0	116	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
1da177e4 LT	117	};
	118
	119	/*
	120	* block elevator interface
	121	*/
165125e1 JA	122	extern void elv_dispatch_sort(struct request_queue , struct request );
165125e1 JA	123	extern void elv_dispatch_add_tail(struct request_queue , struct request );
7eaceacc JA	124	extern void elv_add_request(struct request_queue , struct request , int);
7eaceacc JA	125	extern void __elv_add_request(struct request_queue , struct request , int);
165125e1 JA	126	extern int elv_merge(struct request_queue , struct request , struct bio );
165125e1 JA	127	extern void elv_merge_requests(struct request_queue , struct request ,
1da177e4	128	struct request *);
165125e1	129	extern void elv_merged_request(struct request_queue , struct request , int);
812d4026 DS	130	extern void elv_bio_merged(struct request_queue q, struct request ,
812d4026 DS	131	struct bio *);
165125e1	132	extern void elv_requeue_request(struct request_queue , struct request );
165125e1 JA	133	extern struct request elv_former_request(struct request_queue , struct request *);
	134	extern struct request elv_latter_request(struct request_queue , struct request *);
	135	extern int elv_register_queue(struct request_queue *q);
	136	extern void elv_unregister_queue(struct request_queue *q);
	137	extern int elv_may_queue(struct request_queue *, int);
	138	extern void elv_completed_request(struct request_queue , struct request );
852c788f TH	139	extern int elv_set_request(struct request_queue q, struct request rq,
852c788f TH	140	struct bio *bio, gfp_t gfp_mask);
165125e1	141	extern void elv_put_request(struct request_queue , struct request );
26308eab	142	extern void elv_drain_elevator(struct request_queue *);
1da177e4 LT	143
	144	/*
	145	* io scheduler registration
	146	*/
bb813f4c	147	extern void __init load_default_elevator_module(void);
e567bf71	148	extern int elv_register(struct elevator_type *);
1da177e4 LT	149	extern void elv_unregister(struct elevator_type *);
	150
	151	/*
	152	* io scheduler sysfs switching
	153	*/
165125e1 JA	154	extern ssize_t elv_iosched_show(struct request_queue , char );
165125e1 JA	155	extern ssize_t elv_iosched_store(struct request_queue , const char , size_t);
1da177e4	156
165125e1	157	extern int elevator_init(struct request_queue , char );
b374d18a	158	extern void elevator_exit(struct elevator_queue *);
5dd531a0	159	extern int elevator_change(struct request_queue , const char );
050c8ea8	160	extern bool elv_rq_merge_ok(struct request , struct bio );
d50235b7 JM	161	extern struct elevator_queue elevator_alloc(struct request_queue ,
d50235b7 JM	162	struct elevator_type *);
1da177e4	163
2e662b65 JA	164	/*
	165	* Helper functions.
	166	*/
165125e1 JA	167	extern struct request elv_rb_former_request(struct request_queue , struct request *);
165125e1 JA	168	extern struct request elv_rb_latter_request(struct request_queue , struct request *);
2e662b65 JA	169
	170	/*
	171	* rb support functions.
	172	*/
796d5116	173	extern void elv_rb_add(struct rb_root , struct request );
2e662b65 JA	174	extern void elv_rb_del(struct rb_root , struct request );
	175	extern struct request elv_rb_find(struct rb_root , sector_t);
	176
1da177e4 LT	177	/*
	178	* Return values from elevator merger
	179	*/
	180	#define ELEVATOR_NO_MERGE 0
	181	#define ELEVATOR_FRONT_MERGE 1
	182	#define ELEVATOR_BACK_MERGE 2
	183
	184	/*
	185	* Insertion selection
	186	*/
	187	#define ELEVATOR_INSERT_FRONT 1
	188	#define ELEVATOR_INSERT_BACK 2
	189	#define ELEVATOR_INSERT_SORT 3
797e7dbb	190	#define ELEVATOR_INSERT_REQUEUE 4
ae1b1539	191	#define ELEVATOR_INSERT_FLUSH 5
5e84ea3a	192	#define ELEVATOR_INSERT_SORT_MERGE 6
1da177e4 LT	193
	194	/*
	195	* return values from elevator_may_queue_fn
	196	*/
	197	enum {
	198	ELV_MQUEUE_MAY,
	199	ELV_MQUEUE_NO,
	200	ELV_MQUEUE_MUST,
	201	};
	202
2e46e8b2	203	#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
2e662b65	204	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	205
1fbfdfcd	206	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
d9a74df5	207	#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
1fbfdfcd	208
bb813f4c TH	209	#else /* CONFIG_BLOCK */
	210
	211	static inline void load_default_elevator_module(void) { }
	212
9361401e	213	#endif /* CONFIG_BLOCK */
1da177e4	214	#endif