[linux.git] / include / linux / elevator.h

#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H

#include <linux/percpu.h>

#ifdef CONFIG_BLOCK

struct io_cq;

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 *, 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_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;
};

#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;
};

/*
 * 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
7e5a8794 TH	8	struct io_cq;
7e5a8794 TH	9
165125e1	10	typedef int (elevator_merge_fn) (struct request_queue , struct request *,
1da177e4 LT	11	struct bio *);
1da177e4 LT	12
165125e1	13	typedef void (elevator_merge_req_fn) (struct request_queue , struct request , struct request *);
1da177e4	14
165125e1	15	typedef void (elevator_merged_fn) (struct request_queue , struct request , int);
1da177e4	16
165125e1	17	typedef int (elevator_allow_merge_fn) (struct request_queue , struct request , struct bio *);
da775265	18
812d4026 DS	19	typedef void (elevator_bio_merged_fn) (struct request_queue *,
	20	struct request , struct bio );
	21
165125e1	22	typedef int (elevator_dispatch_fn) (struct request_queue *, int);
1da177e4	23
165125e1	24	typedef void (elevator_add_req_fn) (struct request_queue , struct request );
165125e1 JA	25	typedef struct request (elevator_request_list_fn) (struct request_queue , struct request *);
	26	typedef void (elevator_completed_req_fn) (struct request_queue , struct request );
	27	typedef int (elevator_may_queue_fn) (struct request_queue *, int);
1da177e4	28
9b84cacd	29	typedef void (elevator_init_icq_fn) (struct io_cq *);
7e5a8794	30	typedef void (elevator_exit_icq_fn) (struct io_cq *);
165125e1	31	typedef int (elevator_set_req_fn) (struct request_queue , struct request , gfp_t);
bb37b94c	32	typedef void (elevator_put_req_fn) (struct request *);
165125e1 JA	33	typedef void (elevator_activate_req_fn) (struct request_queue , struct request );
165125e1 JA	34	typedef void (elevator_deactivate_req_fn) (struct request_queue , struct request );
1da177e4	35
165125e1	36	typedef void (elevator_init_fn) (struct request_queue );
b374d18a	37	typedef void (elevator_exit_fn) (struct elevator_queue *);
1da177e4 LT	38
	39	struct elevator_ops
	40	{
	41	elevator_merge_fn *elevator_merge_fn;
	42	elevator_merged_fn *elevator_merged_fn;
	43	elevator_merge_req_fn *elevator_merge_req_fn;
da775265	44	elevator_allow_merge_fn *elevator_allow_merge_fn;
bd87b589 TH	45
	46	/*
	47	* Used for both plugged list and elevator merging and in the
	48	* former case called without queue_lock. Read comment on top of
	49	* attempt_plug_merge() for details.
	50	*/
812d4026	51	elevator_bio_merged_fn *elevator_bio_merged_fn;
1da177e4	52
8922e16c	53	elevator_dispatch_fn *elevator_dispatch_fn;
1da177e4	54	elevator_add_req_fn *elevator_add_req_fn;
8922e16c	55	elevator_activate_req_fn *elevator_activate_req_fn;
1da177e4 LT	56	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
1da177e4 LT	57
1da177e4 LT	58	elevator_completed_req_fn *elevator_completed_req_fn;
	59
	60	elevator_request_list_fn *elevator_former_req_fn;
	61	elevator_request_list_fn *elevator_latter_req_fn;
	62
f1f8cc94 TH	63	elevator_init_icq_fn elevator_init_icq_fn; / see iocontext.h */
f1f8cc94 TH	64	elevator_exit_icq_fn elevator_exit_icq_fn; / ditto */
7e5a8794	65
1da177e4 LT	66	elevator_set_req_fn *elevator_set_req_fn;
	67	elevator_put_req_fn *elevator_put_req_fn;
	68
	69	elevator_may_queue_fn *elevator_may_queue_fn;
	70
	71	elevator_init_fn *elevator_init_fn;
	72	elevator_exit_fn *elevator_exit_fn;
	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	};
	103
	104	/*
54069588	105	* each queue has an elevator_queue associated with it
1da177e4 LT	106	*/
	107	struct elevator_queue
	108	{
22f746e2	109	struct elevator_type *type;
1da177e4 LT	110	void *elevator_data;
1da177e4 LT	111	struct kobject kobj;
3d1ab40f	112	struct mutex sysfs_lock;
9817064b	113	struct hlist_head *hash;
430c62fb	114	unsigned int registered:1;
1da177e4 LT	115	};
	116
	117	/*
	118	* block elevator interface
	119	*/
165125e1 JA	120	extern void elv_dispatch_sort(struct request_queue , struct request );
165125e1 JA	121	extern void elv_dispatch_add_tail(struct request_queue , struct request );
7eaceacc JA	122	extern void elv_add_request(struct request_queue , struct request , int);
7eaceacc JA	123	extern void __elv_add_request(struct request_queue , struct request , int);
165125e1	124	extern int elv_merge(struct request_queue , struct request , struct bio );
73c10101	125	extern int elv_try_merge(struct request , struct bio );
165125e1	126	extern void elv_merge_requests(struct request_queue , struct request ,
1da177e4	127	struct request *);
165125e1	128	extern void elv_merged_request(struct request_queue , struct request , int);
812d4026 DS	129	extern void elv_bio_merged(struct request_queue q, struct request ,
812d4026 DS	130	struct bio *);
165125e1	131	extern void elv_requeue_request(struct request_queue , struct request );
165125e1 JA	132	extern struct request elv_former_request(struct request_queue , struct request *);
	133	extern struct request elv_latter_request(struct request_queue , struct request *);
	134	extern int elv_register_queue(struct request_queue *q);
	135	extern void elv_unregister_queue(struct request_queue *q);
	136	extern int elv_may_queue(struct request_queue *, int);
11914a53	137	extern void elv_abort_queue(struct request_queue *);
165125e1 JA	138	extern void elv_completed_request(struct request_queue , struct request );
	139	extern int elv_set_request(struct request_queue , struct request , gfp_t);
	140	extern void elv_put_request(struct request_queue , struct request );
26308eab	141	extern void elv_drain_elevator(struct request_queue *);
1da177e4 LT	142
	143	/*
	144	* io scheduler registration
	145	*/
3d3c2379	146	extern int elv_register(struct elevator_type *);
1da177e4 LT	147	extern void elv_unregister(struct elevator_type *);
	148
	149	/*
	150	* io scheduler sysfs switching
	151	*/
165125e1 JA	152	extern ssize_t elv_iosched_show(struct request_queue , char );
165125e1 JA	153	extern ssize_t elv_iosched_store(struct request_queue , const char , size_t);
1da177e4	154
165125e1	155	extern int elevator_init(struct request_queue , char );
b374d18a	156	extern void elevator_exit(struct elevator_queue *);
5dd531a0	157	extern int elevator_change(struct request_queue , const char );
1da177e4	158	extern int elv_rq_merge_ok(struct request , struct bio );
1da177e4	159
2e662b65 JA	160	/*
	161	* Helper functions.
	162	*/
165125e1 JA	163	extern struct request elv_rb_former_request(struct request_queue , struct request *);
165125e1 JA	164	extern struct request elv_rb_latter_request(struct request_queue , struct request *);
2e662b65 JA	165
	166	/*
	167	* rb support functions.
	168	*/
796d5116	169	extern void elv_rb_add(struct rb_root , struct request );
2e662b65 JA	170	extern void elv_rb_del(struct rb_root , struct request );
	171	extern struct request elv_rb_find(struct rb_root , sector_t);
	172
1da177e4 LT	173	/*
	174	* Return values from elevator merger
	175	*/
	176	#define ELEVATOR_NO_MERGE 0
	177	#define ELEVATOR_FRONT_MERGE 1
	178	#define ELEVATOR_BACK_MERGE 2
	179
	180	/*
	181	* Insertion selection
	182	*/
	183	#define ELEVATOR_INSERT_FRONT 1
	184	#define ELEVATOR_INSERT_BACK 2
	185	#define ELEVATOR_INSERT_SORT 3
797e7dbb	186	#define ELEVATOR_INSERT_REQUEUE 4
ae1b1539	187	#define ELEVATOR_INSERT_FLUSH 5
5e84ea3a	188	#define ELEVATOR_INSERT_SORT_MERGE 6
1da177e4 LT	189
	190	/*
	191	* return values from elevator_may_queue_fn
	192	*/
	193	enum {
	194	ELV_MQUEUE_MAY,
	195	ELV_MQUEUE_NO,
	196	ELV_MQUEUE_MUST,
	197	};
	198
2e46e8b2	199	#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
2e662b65	200	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	201
1fbfdfcd	202	/*
c7c22e4d	203	* Hack to reuse the csd.list list_head as the fifo time holder while
1fbfdfcd JA	204	* the request is in the io scheduler. Saves an unsigned long in rq.
1fbfdfcd JA	205	*/
c7c22e4d JA	206	#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
c7c22e4d JA	207	#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
1fbfdfcd JA	208	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
	209	#define rq_fifo_clear(rq) do { \
	210	list_del_init(&(rq)->queuelist); \
c7c22e4d	211	INIT_LIST_HEAD(&(rq)->csd.list); \
1fbfdfcd JA	212	} while (0)
1fbfdfcd JA	213
9361401e	214	#endif /* CONFIG_BLOCK */
1da177e4	215	#endif