diff options
Diffstat (limited to 'include/linux/elevator.h')
| -rw-r--r-- | include/linux/elevator.h | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/include/linux/elevator.h b/include/linux/elevator.h new file mode 100644 index 00000000..7d4e0356 --- /dev/null +++ b/include/linux/elevator.h @@ -0,0 +1,208 @@ +#ifndef _LINUX_ELEVATOR_H +#define _LINUX_ELEVATOR_H + +#include <linux/percpu.h> + +#ifdef CONFIG_BLOCK + +struct io_cq; + +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 *, 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) (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; +}; + +/* + * 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; + struct hlist_head *hash; + unsigned int registered:1; +}; + +/* + * 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_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 *); +extern void elv_drain_elevator(struct request_queue *); + +/* + * io scheduler registration + */ +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 *); + +/* + * 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) + +/* + * 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) + +#endif /* CONFIG_BLOCK */ +#endif |