[deliverable/linux.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;

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 *);
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_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;
};

#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_abort_queue(struct request_queue *);
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 *);

/*
 * 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)

#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 TH	9	struct io_cq;
7e5a8794 TH	10
165125e1	11	typedef int (elevator_merge_fn) (struct request_queue , struct request *,
1da177e4 LT	12	struct bio *);
1da177e4 LT	13
165125e1	14	typedef void (elevator_merge_req_fn) (struct request_queue , struct request , struct request *);
1da177e4	15
165125e1	16	typedef void (elevator_merged_fn) (struct request_queue , struct request , int);
1da177e4	17
165125e1	18	typedef int (elevator_allow_merge_fn) (struct request_queue , struct request , struct bio *);
da775265	19
812d4026 DS	20	typedef void (elevator_bio_merged_fn) (struct request_queue *,
	21	struct request , struct bio );
	22
165125e1	23	typedef int (elevator_dispatch_fn) (struct request_queue *, int);
1da177e4	24
165125e1	25	typedef void (elevator_add_req_fn) (struct request_queue , struct request );
165125e1 JA	26	typedef struct request (elevator_request_list_fn) (struct request_queue , struct request *);
	27	typedef void (elevator_completed_req_fn) (struct request_queue , struct request );
	28	typedef int (elevator_may_queue_fn) (struct request_queue *, int);
1da177e4	29
9b84cacd	30	typedef void (elevator_init_icq_fn) (struct io_cq *);
7e5a8794	31	typedef void (elevator_exit_icq_fn) (struct io_cq *);
852c788f TH	32	typedef int (elevator_set_req_fn) (struct request_queue , struct request ,
852c788f TH	33	struct bio *, gfp_t);
bb37b94c	34	typedef void (elevator_put_req_fn) (struct request *);
165125e1 JA	35	typedef void (elevator_activate_req_fn) (struct request_queue , struct request );
165125e1 JA	36	typedef void (elevator_deactivate_req_fn) (struct request_queue , struct request );
1da177e4	37
b2fab5ac	38	typedef int (elevator_init_fn) (struct request_queue *);
b374d18a	39	typedef void (elevator_exit_fn) (struct elevator_queue *);
1da177e4 LT	40
	41	struct elevator_ops
	42	{
	43	elevator_merge_fn *elevator_merge_fn;
	44	elevator_merged_fn *elevator_merged_fn;
	45	elevator_merge_req_fn *elevator_merge_req_fn;
da775265	46	elevator_allow_merge_fn *elevator_allow_merge_fn;
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
f1f8cc94 TH	59	elevator_init_icq_fn elevator_init_icq_fn; / see iocontext.h */
f1f8cc94 TH	60	elevator_exit_icq_fn elevator_exit_icq_fn; / ditto */
7e5a8794	61
1da177e4 LT	62	elevator_set_req_fn *elevator_set_req_fn;
	63	elevator_put_req_fn *elevator_put_req_fn;
	64
	65	elevator_may_queue_fn *elevator_may_queue_fn;
	66
	67	elevator_init_fn *elevator_init_fn;
	68	elevator_exit_fn *elevator_exit_fn;
	69	};
	70
	71	#define ELV_NAME_MAX (16)
	72
e572ec7e AV	73	struct elv_fs_entry {
e572ec7e AV	74	struct attribute attr;
b374d18a JA	75	ssize_t (show)(struct elevator_queue , char *);
b374d18a JA	76	ssize_t (store)(struct elevator_queue , const char *, size_t);
e572ec7e AV	77	};
e572ec7e AV	78
1da177e4 LT	79	/*
	80	* identifies an elevator type, such as AS or deadline
	81	*/
	82	struct elevator_type
	83	{
3d3c2379 TH	84	/* managed by elevator core */
	85	struct kmem_cache *icq_cache;
	86
	87	/* fields provided by elevator implementation */
1da177e4	88	struct elevator_ops ops;
f1f8cc94 TH	89	size_t icq_size; /* see iocontext.h */
f1f8cc94 TH	90	size_t icq_align; /* ditto */
e572ec7e	91	struct elv_fs_entry *elevator_attrs;
1da177e4 LT	92	char elevator_name[ELV_NAME_MAX];
1da177e4 LT	93	struct module *elevator_owner;
3d3c2379 TH	94
	95	/* managed by elevator core */
	96	char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
22f746e2	97	struct list_head list;
1da177e4 LT	98	};
1da177e4 LT	99
242d98f0 SL	100	#define ELV_HASH_BITS 6
242d98f0 SL	101
1da177e4	102	/*
54069588	103	* each queue has an elevator_queue associated with it
1da177e4 LT	104	*/
	105	struct elevator_queue
	106	{
22f746e2	107	struct elevator_type *type;
1da177e4 LT	108	void *elevator_data;
1da177e4 LT	109	struct kobject kobj;
3d1ab40f	110	struct mutex sysfs_lock;
430c62fb	111	unsigned int registered:1;
242d98f0	112	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
1da177e4 LT	113	};
	114
	115	/*
	116	* block elevator interface
	117	*/
165125e1 JA	118	extern void elv_dispatch_sort(struct request_queue , struct request );
165125e1 JA	119	extern void elv_dispatch_add_tail(struct request_queue , struct request );
7eaceacc JA	120	extern void elv_add_request(struct request_queue , struct request , int);
7eaceacc JA	121	extern void __elv_add_request(struct request_queue , struct request , int);
165125e1 JA	122	extern int elv_merge(struct request_queue , struct request , struct bio );
165125e1 JA	123	extern void elv_merge_requests(struct request_queue , struct request ,
1da177e4	124	struct request *);
165125e1	125	extern void elv_merged_request(struct request_queue , struct request , int);
812d4026 DS	126	extern void elv_bio_merged(struct request_queue q, struct request ,
812d4026 DS	127	struct bio *);
165125e1	128	extern void elv_requeue_request(struct request_queue , struct request );
165125e1 JA	129	extern struct request elv_former_request(struct request_queue , struct request *);
	130	extern struct request elv_latter_request(struct request_queue , struct request *);
	131	extern int elv_register_queue(struct request_queue *q);
	132	extern void elv_unregister_queue(struct request_queue *q);
	133	extern int elv_may_queue(struct request_queue *, int);
11914a53	134	extern void elv_abort_queue(struct request_queue *);
165125e1	135	extern void elv_completed_request(struct request_queue , struct request );
852c788f TH	136	extern int elv_set_request(struct request_queue q, struct request rq,
852c788f TH	137	struct bio *bio, gfp_t gfp_mask);
165125e1	138	extern void elv_put_request(struct request_queue , struct request );
26308eab	139	extern void elv_drain_elevator(struct request_queue *);
1da177e4 LT	140
	141	/*
	142	* io scheduler registration
	143	*/
bb813f4c	144	extern void __init load_default_elevator_module(void);
3d3c2379	145	extern int elv_register(struct elevator_type *);
1da177e4 LT	146	extern void elv_unregister(struct elevator_type *);
	147
	148	/*
	149	* io scheduler sysfs switching
	150	*/
165125e1 JA	151	extern ssize_t elv_iosched_show(struct request_queue , char );
165125e1 JA	152	extern ssize_t elv_iosched_store(struct request_queue , const char , size_t);
1da177e4	153
165125e1	154	extern int elevator_init(struct request_queue , char );
b374d18a	155	extern void elevator_exit(struct elevator_queue *);
5dd531a0	156	extern int elevator_change(struct request_queue , const char );
050c8ea8	157	extern bool elv_rq_merge_ok(struct request , struct bio );
1da177e4	158
2e662b65 JA	159	/*
	160	* Helper functions.
	161	*/
165125e1 JA	162	extern struct request elv_rb_former_request(struct request_queue , struct request *);
165125e1 JA	163	extern struct request elv_rb_latter_request(struct request_queue , struct request *);
2e662b65 JA	164
	165	/*
	166	* rb support functions.
	167	*/
796d5116	168	extern void elv_rb_add(struct rb_root , struct request );
2e662b65 JA	169	extern void elv_rb_del(struct rb_root , struct request );
	170	extern struct request elv_rb_find(struct rb_root , sector_t);
	171
1da177e4 LT	172	/*
	173	* Return values from elevator merger
	174	*/
	175	#define ELEVATOR_NO_MERGE 0
	176	#define ELEVATOR_FRONT_MERGE 1
	177	#define ELEVATOR_BACK_MERGE 2
	178
	179	/*
	180	* Insertion selection
	181	*/
	182	#define ELEVATOR_INSERT_FRONT 1
	183	#define ELEVATOR_INSERT_BACK 2
	184	#define ELEVATOR_INSERT_SORT 3
797e7dbb	185	#define ELEVATOR_INSERT_REQUEUE 4
ae1b1539	186	#define ELEVATOR_INSERT_FLUSH 5
5e84ea3a	187	#define ELEVATOR_INSERT_SORT_MERGE 6
1da177e4 LT	188
	189	/*
	190	* return values from elevator_may_queue_fn
	191	*/
	192	enum {
	193	ELV_MQUEUE_MAY,
	194	ELV_MQUEUE_NO,
	195	ELV_MQUEUE_MUST,
	196	};
	197
2e46e8b2	198	#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
2e662b65	199	#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
1b47f531	200
1fbfdfcd	201	/*
c7c22e4d	202	* Hack to reuse the csd.list list_head as the fifo time holder while
1fbfdfcd JA	203	* the request is in the io scheduler. Saves an unsigned long in rq.
1fbfdfcd JA	204	*/
c7c22e4d JA	205	#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
c7c22e4d JA	206	#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
1fbfdfcd JA	207	#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
	208	#define rq_fifo_clear(rq) do { \
	209	list_del_init(&(rq)->queuelist); \
c7c22e4d	210	INIT_LIST_HEAD(&(rq)->csd.list); \
1fbfdfcd JA	211	} while (0)
1fbfdfcd JA	212
bb813f4c TH	213	#else /* CONFIG_BLOCK */
	214
	215	static inline void load_default_elevator_module(void) { }
	216
9361401e	217	#endif /* CONFIG_BLOCK */
1da177e4	218	#endif