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#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H
typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
struct bio *);
typedef void (elevator_merge_cleanup_fn) (request_queue_t *, struct request *, int);
typedef void (elevator_merge_req_fn) (struct request *, struct request *);
typedef struct request *(elevator_next_req_fn) (request_queue_t *);
typedef void (elevator_add_req_fn) (request_queue_t *, struct request *, struct list_head *);
typedef int (elevator_queue_empty_fn) (request_queue_t *);
typedef void (elevator_remove_req_fn) (request_queue_t *, struct request *);
typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
typedef void (elevator_exit_fn) (request_queue_t *, elevator_t *);
struct elevator_s
{
elevator_merge_fn *elevator_merge_fn;
elevator_merge_cleanup_fn *elevator_merge_cleanup_fn;
elevator_merge_req_fn *elevator_merge_req_fn;
elevator_next_req_fn *elevator_next_req_fn;
elevator_add_req_fn *elevator_add_req_fn;
elevator_remove_req_fn *elevator_remove_req_fn;
elevator_queue_empty_fn *elevator_queue_empty_fn;
elevator_init_fn *elevator_init_fn;
elevator_exit_fn *elevator_exit_fn;
void *elevator_data;
};
/*
* block elevator interface
*/
extern void __elv_add_request(request_queue_t *, struct request *,
struct list_head *);
extern struct request *__elv_next_request(request_queue_t *);
extern void elv_merge_cleanup(request_queue_t *, struct request *, int);
extern int elv_merge(request_queue_t *, struct request **, struct bio *);
extern void elv_merge_requests(request_queue_t *, struct request *,
struct request *);
extern void elv_remove_request(request_queue_t *, struct request *);
/*
* noop I/O scheduler. always merges, always inserts new request at tail
*/
extern elevator_t elevator_noop;
/*
* elevator linus. based on linus ideas of starvation control, using
* sequencing to manage inserts and merges.
*/
extern elevator_t elevator_linus;
#define elv_linus_sequence(rq) ((long)(rq)->elevator_private)
/*
* use the /proc/iosched interface, all the below is history ->
*/
typedef struct blkelv_ioctl_arg_s {
int queue_ID;
int read_latency;
int write_latency;
int max_bomb_segments;
} blkelv_ioctl_arg_t;
#define BLKELVGET _IOR(0x12,106,sizeof(blkelv_ioctl_arg_t))
#define BLKELVSET _IOW(0x12,107,sizeof(blkelv_ioctl_arg_t))
extern int elevator_init(request_queue_t *, elevator_t *, elevator_t);
extern void elevator_exit(request_queue_t *, elevator_t *);
/*
* Return values from elevator merger
*/
#define ELEVATOR_NO_MERGE 0
#define ELEVATOR_FRONT_MERGE 1
#define ELEVATOR_BACK_MERGE 2
/*
* will change once we move to a more complex data structure than a simple
* list for pending requests
*/
#define elv_queue_empty(q) list_empty(&(q)->queue_head)
#endif
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