8922e16cf6
Implements generic dispatch queue which can replace all dispatch queues implemented by each iosched. This reduces code duplication, eases enforcing semantics over dispatch queue, and simplifies specific ioscheds. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <axboe@suse.de>
143 lines
4.6 KiB
C
143 lines
4.6 KiB
C
#ifndef _LINUX_ELEVATOR_H
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#define _LINUX_ELEVATOR_H
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typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
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struct bio *);
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typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *);
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typedef void (elevator_merged_fn) (request_queue_t *, struct request *);
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typedef int (elevator_dispatch_fn) (request_queue_t *, int);
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typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
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typedef int (elevator_queue_empty_fn) (request_queue_t *);
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typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
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typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
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typedef int (elevator_may_queue_fn) (request_queue_t *, int, struct bio *);
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typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, struct bio *, int);
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typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
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typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
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typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
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typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
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typedef void (elevator_exit_fn) (elevator_t *);
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struct elevator_ops
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{
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elevator_merge_fn *elevator_merge_fn;
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elevator_merged_fn *elevator_merged_fn;
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elevator_merge_req_fn *elevator_merge_req_fn;
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elevator_dispatch_fn *elevator_dispatch_fn;
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elevator_add_req_fn *elevator_add_req_fn;
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elevator_activate_req_fn *elevator_activate_req_fn;
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elevator_deactivate_req_fn *elevator_deactivate_req_fn;
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elevator_queue_empty_fn *elevator_queue_empty_fn;
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elevator_completed_req_fn *elevator_completed_req_fn;
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elevator_request_list_fn *elevator_former_req_fn;
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elevator_request_list_fn *elevator_latter_req_fn;
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elevator_set_req_fn *elevator_set_req_fn;
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elevator_put_req_fn *elevator_put_req_fn;
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elevator_may_queue_fn *elevator_may_queue_fn;
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elevator_init_fn *elevator_init_fn;
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elevator_exit_fn *elevator_exit_fn;
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};
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#define ELV_NAME_MAX (16)
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/*
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* identifies an elevator type, such as AS or deadline
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*/
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struct elevator_type
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{
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struct list_head list;
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struct elevator_ops ops;
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struct elevator_type *elevator_type;
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struct kobj_type *elevator_ktype;
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char elevator_name[ELV_NAME_MAX];
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struct module *elevator_owner;
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};
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/*
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* each queue has an elevator_queue assoicated with it
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*/
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struct elevator_queue
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{
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struct elevator_ops *ops;
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void *elevator_data;
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struct kobject kobj;
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struct elevator_type *elevator_type;
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};
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/*
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* block elevator interface
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*/
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extern void elv_dispatch_insert(request_queue_t *, struct request *, int);
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extern void elv_add_request(request_queue_t *, struct request *, int, int);
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extern void __elv_add_request(request_queue_t *, struct request *, int, int);
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extern int elv_merge(request_queue_t *, struct request **, struct bio *);
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extern void elv_merge_requests(request_queue_t *, struct request *,
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struct request *);
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extern void elv_merged_request(request_queue_t *, struct request *);
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extern void elv_dequeue_request(request_queue_t *, struct request *);
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extern void elv_requeue_request(request_queue_t *, struct request *);
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extern int elv_queue_empty(request_queue_t *);
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extern struct request *elv_next_request(struct request_queue *q);
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extern struct request *elv_former_request(request_queue_t *, struct request *);
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extern struct request *elv_latter_request(request_queue_t *, struct request *);
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extern int elv_register_queue(request_queue_t *q);
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extern void elv_unregister_queue(request_queue_t *q);
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extern int elv_may_queue(request_queue_t *, int, struct bio *);
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extern void elv_completed_request(request_queue_t *, struct request *);
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extern int elv_set_request(request_queue_t *, struct request *, struct bio *, int);
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extern void elv_put_request(request_queue_t *, struct request *);
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/*
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* io scheduler registration
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*/
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extern int elv_register(struct elevator_type *);
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extern void elv_unregister(struct elevator_type *);
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/*
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* io scheduler sysfs switching
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*/
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extern ssize_t elv_iosched_show(request_queue_t *, char *);
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extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
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extern int elevator_init(request_queue_t *, char *);
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extern void elevator_exit(elevator_t *);
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extern int elv_rq_merge_ok(struct request *, struct bio *);
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extern int elv_try_merge(struct request *, struct bio *);
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extern int elv_try_last_merge(request_queue_t *, struct bio *);
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/*
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* Return values from elevator merger
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*/
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#define ELEVATOR_NO_MERGE 0
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#define ELEVATOR_FRONT_MERGE 1
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#define ELEVATOR_BACK_MERGE 2
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/*
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* Insertion selection
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*/
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#define ELEVATOR_INSERT_FRONT 1
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#define ELEVATOR_INSERT_BACK 2
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#define ELEVATOR_INSERT_SORT 3
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/*
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* return values from elevator_may_queue_fn
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*/
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enum {
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ELV_MQUEUE_MAY,
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ELV_MQUEUE_NO,
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ELV_MQUEUE_MUST,
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};
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#endif
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