diff options
Diffstat (limited to 'block/elevator.h')
| -rw-r--r-- | block/elevator.h | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/block/elevator.h b/block/elevator.h new file mode 100644 index 000000000000..a9d092c5a9e8 --- /dev/null +++ b/block/elevator.h @@ -0,0 +1,222 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ELEVATOR_H +#define _ELEVATOR_H + +#include <linux/percpu.h> +#include <linux/hashtable.h> +#include "blk-mq.h" + +struct io_cq; +struct elevator_type; +struct blk_mq_debugfs_attr; + +/* + * Return values from elevator merger + */ +enum elv_merge { + ELEVATOR_NO_MERGE = 0, + ELEVATOR_FRONT_MERGE = 1, + ELEVATOR_BACK_MERGE = 2, + ELEVATOR_DISCARD_MERGE = 3, +}; + +struct blk_mq_alloc_data; +struct blk_mq_hw_ctx; + +struct elevator_tags { + /* num. of hardware queues for which tags are allocated */ + unsigned int nr_hw_queues; + /* depth used while allocating tags */ + unsigned int nr_requests; + /* shared tag is stored at index 0 */ + struct blk_mq_tags *tags[]; +}; + +struct elevator_resources { + /* holds elevator data */ + void *data; + /* holds elevator tags */ + struct elevator_tags *et; +}; + +/* Holding context data for changing elevator */ +struct elv_change_ctx { + const char *name; + bool no_uevent; + + /* for unregistering old elevator */ + struct elevator_queue *old; + /* for registering new elevator */ + struct elevator_queue *new; + /* store elevator type */ + struct elevator_type *type; + /* store elevator resources */ + struct elevator_resources res; +}; + +struct elevator_mq_ops { + int (*init_sched)(struct request_queue *, struct elevator_queue *); + void (*exit_sched)(struct elevator_queue *); + int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int); + void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int); + void (*depth_updated)(struct request_queue *); + void *(*alloc_sched_data)(struct request_queue *); + void (*free_sched_data)(void *); + + bool (*allow_merge)(struct request_queue *, struct request *, struct bio *); + bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int); + int (*request_merge)(struct request_queue *q, struct request **, struct bio *); + void (*request_merged)(struct request_queue *, struct request *, enum elv_merge); + void (*requests_merged)(struct request_queue *, struct request *, struct request *); + void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *); + void (*prepare_request)(struct request *); + void (*finish_request)(struct request *); + void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list, + blk_insert_t flags); + struct request *(*dispatch_request)(struct blk_mq_hw_ctx *); + bool (*has_work)(struct blk_mq_hw_ctx *); + void (*completed_request)(struct request *, u64); + void (*requeue_request)(struct request *); + struct request *(*former_request)(struct request_queue *, struct request *); + struct request *(*next_request)(struct request_queue *, struct request *); + void (*init_icq)(struct io_cq *); + void (*exit_icq)(struct io_cq *); +}; + +#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_mq_ops ops; + + size_t icq_size; /* see iocontext.h */ + size_t icq_align; /* ditto */ + const struct elv_fs_entry *elevator_attrs; + const char *elevator_name; + const char *elevator_alias; + struct module *elevator_owner; +#ifdef CONFIG_BLK_DEBUG_FS + const struct blk_mq_debugfs_attr *queue_debugfs_attrs; + const struct blk_mq_debugfs_attr *hctx_debugfs_attrs; +#endif + + /* managed by elevator core */ + char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */ + struct list_head list; +}; + +static inline bool elevator_tryget(struct elevator_type *e) +{ + return try_module_get(e->elevator_owner); +} + +static inline void __elevator_get(struct elevator_type *e) +{ + __module_get(e->elevator_owner); +} + +static inline void elevator_put(struct elevator_type *e) +{ + module_put(e->elevator_owner); +} + +#define ELV_HASH_BITS 6 + +void elv_rqhash_del(struct request_queue *q, struct request *rq); +void elv_rqhash_add(struct request_queue *q, struct request *rq); +void elv_rqhash_reposition(struct request_queue *q, struct request *rq); +struct request *elv_rqhash_find(struct request_queue *q, sector_t offset); + +/* + * each queue has an elevator_queue associated with it + */ +struct elevator_queue +{ + struct elevator_type *type; + struct elevator_tags *et; + void *elevator_data; + struct kobject kobj; + struct mutex sysfs_lock; + unsigned long flags; + DECLARE_HASHTABLE(hash, ELV_HASH_BITS); +}; + +#define ELEVATOR_FLAG_REGISTERED 0 +#define ELEVATOR_FLAG_DYING 1 +#define ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT 2 + +/* + * block elevator interface + */ +extern enum elv_merge 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 *, + enum elv_merge); +extern bool elv_attempt_insert_merge(struct request_queue *, struct request *, + struct list_head *); +extern struct request *elv_former_request(struct request_queue *, struct request *); +extern struct request *elv_latter_request(struct request_queue *, struct request *); + +/* + * io scheduler registration + */ +extern int elv_register(struct elevator_type *); +extern void elv_unregister(struct elevator_type *); + +/* + * io scheduler sysfs switching + */ +ssize_t elv_iosched_show(struct gendisk *disk, char *page); +ssize_t elv_iosched_store(struct gendisk *disk, const char *page, size_t count); + +extern bool elv_bio_merge_ok(struct request *, struct bio *); +struct elevator_queue *elevator_alloc(struct request_queue *, + struct elevator_type *, struct elevator_resources *); + +/* + * 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); + +/* + * 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 + +#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) + +void blk_mq_sched_reg_debugfs(struct request_queue *q); +void blk_mq_sched_unreg_debugfs(struct request_queue *q); + +#endif /* _ELEVATOR_H */ |