include/linux/elevator.h

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This source file includes following definitions.
load_default_elevator_module
#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 *);

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_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
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root/include/linux/elevator.h

INCLUDED FROM

DEFINITIONS
