#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 int (elevator_dispatch_fn) (struct request_queue *, int);

typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);

typedef int (elevator_queue_empty_fn) (struct request_queue *);

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) (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_allow_merge_fn *elevator_allow_merge_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(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, int);

extern void __elv_add_request(struct request_queue *, struct request *, int, int);

extern void elv_insert(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_dequeue_request(struct request_queue *, struct request *);

extern void elv_requeue_request(struct request_queue *, struct request *);

extern int elv_queue_empty(struct request_queue *);

extern struct request *elv_next_request(struct request_queue *q);

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 *);

/*

 * io scheduler registration

 */

extern void 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(elevator_t *);

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 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 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)

/*

 * 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