2fdd82bd88
elv_register() always returns 0, and there isn't anything it does where it should return an error (the only error condition is so grave that it's handled with a BUG_ON). Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
211 lines
6.7 KiB
C
211 lines
6.7 KiB
C
#ifndef _LINUX_ELEVATOR_H
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#define _LINUX_ELEVATOR_H
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#include <linux/percpu.h>
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#ifdef CONFIG_BLOCK
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typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
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struct bio *);
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typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
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typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
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typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
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typedef int (elevator_dispatch_fn) (struct request_queue *, int);
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typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
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typedef int (elevator_queue_empty_fn) (struct request_queue *);
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typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
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typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
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typedef int (elevator_may_queue_fn) (struct request_queue *, int);
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typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
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typedef void (elevator_put_req_fn) (struct request *);
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typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
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typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
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typedef void *(elevator_init_fn) (struct request_queue *);
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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_allow_merge_fn *elevator_allow_merge_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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void (*trim)(struct io_context *);
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};
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#define ELV_NAME_MAX (16)
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struct elv_fs_entry {
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struct attribute attr;
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ssize_t (*show)(elevator_t *, char *);
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ssize_t (*store)(elevator_t *, const char *, size_t);
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};
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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 elv_fs_entry *elevator_attrs;
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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 associated 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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struct mutex sysfs_lock;
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struct hlist_head *hash;
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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_sort(struct request_queue *, struct request *);
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extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
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extern void elv_add_request(struct request_queue *, struct request *, int, int);
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extern void __elv_add_request(struct request_queue *, struct request *, int, int);
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extern void elv_insert(struct request_queue *, struct request *, int);
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extern int elv_merge(struct request_queue *, struct request **, struct bio *);
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extern void elv_merge_requests(struct request_queue *, struct request *,
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struct request *);
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extern void elv_merged_request(struct request_queue *, struct request *, int);
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extern void elv_dequeue_request(struct request_queue *, struct request *);
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extern void elv_requeue_request(struct request_queue *, struct request *);
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extern int elv_queue_empty(struct request_queue *);
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extern struct request *elv_next_request(struct request_queue *q);
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extern struct request *elv_former_request(struct request_queue *, struct request *);
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extern struct request *elv_latter_request(struct request_queue *, struct request *);
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extern int elv_register_queue(struct request_queue *q);
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extern void elv_unregister_queue(struct request_queue *q);
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extern int elv_may_queue(struct request_queue *, int);
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extern void elv_completed_request(struct request_queue *, struct request *);
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extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
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extern void elv_put_request(struct request_queue *, struct request *);
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/*
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* io scheduler registration
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*/
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extern void 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(struct request_queue *, char *);
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extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
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extern int elevator_init(struct request_queue *, 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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/*
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* Helper functions.
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*/
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extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
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extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
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/*
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* rb support functions.
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*/
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extern struct request *elv_rb_add(struct rb_root *, struct request *);
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extern void elv_rb_del(struct rb_root *, struct request *);
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extern struct request *elv_rb_find(struct rb_root *, sector_t);
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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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#define ELEVATOR_INSERT_REQUEUE 4
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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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#define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
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#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
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/*
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* Hack to reuse the donelist list_head as the fifo time holder while
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* the request is in the io scheduler. Saves an unsigned long in rq.
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*/
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#define rq_fifo_time(rq) ((unsigned long) (rq)->donelist.next)
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#define rq_set_fifo_time(rq,exp) ((rq)->donelist.next = (void *) (exp))
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#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
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#define rq_fifo_clear(rq) do { \
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list_del_init(&(rq)->queuelist); \
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INIT_LIST_HEAD(&(rq)->donelist); \
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} while (0)
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/*
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* io context count accounting
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*/
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#define elv_ioc_count_mod(name, __val) \
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do { \
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preempt_disable(); \
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__get_cpu_var(name) += (__val); \
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preempt_enable(); \
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} while (0)
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#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
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#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
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#define elv_ioc_count_read(name) \
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({ \
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unsigned long __val = 0; \
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int __cpu; \
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smp_wmb(); \
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for_each_possible_cpu(__cpu) \
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__val += per_cpu(name, __cpu); \
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__val; \
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})
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#endif /* CONFIG_BLOCK */
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#endif
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