block/elevator.h

Source file repositories/reference/linux-study-clean/block/elevator.h

File Facts

System
Linux kernel
Corpus path
block/elevator.h
Extension
.h
Size
6592 bytes
Lines
222
Domain
Representative Device Path
Bucket
PCIe NVMe Storage Path
Inferred role
Representative Device Path: implementation source
Status
source implementation candidate

Why This File Exists

Part of the selected hardware vertical slice: PCI discovery, driver binding, NVMe queues, block requests, DMA, interrupts, and completion.

Dependency Surface

Detected Declarations

Annotated Snippet

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

Annotation

Implementation Notes