block/blk-stat.h

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

File Facts

System
Linux kernel
Corpus path
block/blk-stat.h
Extension
.h
Size
4908 bytes
Lines
178
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 blk_stat_callback {
	/**
	 * @list: RCU list of callbacks for a &struct request_queue.
	 */
	struct list_head list;

	/**
	 * @timer: Timer for the next callback invocation.
	 */
	struct timer_list timer;

	/**
	 * @cpu_stat: Per-cpu statistics buckets.
	 */
	struct blk_rq_stat __percpu *cpu_stat;

	/**
	 * @bucket_fn: Given a request, returns which statistics bucket it
	 * should be accounted under. Return -1 for no bucket for this
	 * request.
	 */
	int (*bucket_fn)(const struct request *);

	/**
	 * @buckets: Number of statistics buckets.
	 */
	unsigned int buckets;

	/**
	 * @stat: Array of statistics buckets.
	 */
	struct blk_rq_stat *stat;

	/**
	 * @timer_fn: Callback function.
	 */
	void (*timer_fn)(struct blk_stat_callback *);

	/**
	 * @data: Private pointer for the user.
	 */
	void *data;

	/**
	 * @rcu: rcu list head
	 */
	struct rcu_head rcu;
};

struct blk_queue_stats *blk_alloc_queue_stats(void);
void blk_free_queue_stats(struct blk_queue_stats *);

void blk_stat_add(struct request *rq, u64 now);

/* record time/size info in request but not add a callback */
void blk_stat_enable_accounting(struct request_queue *q);
void blk_stat_disable_accounting(struct request_queue *q);

/**
 * blk_stat_alloc_callback() - Allocate a block statistics callback.
 * @timer_fn: Timer callback function.
 * @bucket_fn: Bucket callback function.
 * @buckets: Number of statistics buckets.
 * @data: Value for the @data field of the &struct blk_stat_callback.
 *
 * See &struct blk_stat_callback for details on the callback functions.
 *
 * Return: &struct blk_stat_callback on success or NULL on ENOMEM.
 */
struct blk_stat_callback *
blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
			int (*bucket_fn)(const struct request *),
			unsigned int buckets, void *data);

/**
 * blk_stat_add_callback() - Add a block statistics callback to be run on a
 * request queue.
 * @q: The request queue.
 * @cb: The callback.
 *
 * Note that a single &struct blk_stat_callback can only be added to a single
 * &struct request_queue.
 */
void blk_stat_add_callback(struct request_queue *q,
			   struct blk_stat_callback *cb);

/**
 * blk_stat_remove_callback() - Remove a block statistics callback from a
 * request queue.
 * @q: The request queue.

Annotation

Implementation Notes