/* SPDX-License-Identifier: GPL-2.0 */#ifndef BLK_STAT_H#define BLK_STAT_H #include <linux/kernel.h>#include <linux/blkdev.h>#include <linux/ktime.h>#include <linux/rcupdate.h>#include <linux/timer.h> /** * struct blk_stat_callback - Block statistics callback. * * A &struct blk_stat_callback is associated with a &struct request_queue. While * @timer is active, that queue's request completion latencies are sorted into * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked. */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. * @cb: The callback. * * When this returns, the callback is not running on any CPUs and will not be * called again unless readded. */void blk_stat_remove_callback(struct request_queue *q,			      struct blk_stat_callback *cb); /** * blk_stat_free_callback() - Free a block statistics callback. * @cb: The callback. * * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must * not be associated with a request queue. I.e., if it was previously added with * blk_stat_add_callback(), it must also have been removed since then with * blk_stat_remove_callback(). */void blk_stat_free_callback(struct blk_stat_callback *cb); /** * blk_stat_is_active() - Check if a block statistics callback is currently * gathering statistics. * @cb: The callback. * * Returns: %true iff the callback is active. */static inline bool blk_stat_is_active(struct blk_stat_callback *cb){	return timer_pending(&cb->timer);} /** * blk_stat_activate_nsecs() - Gather block statistics during a time window in * nanoseconds. * @cb: The callback. * @nsecs: Number of nanoseconds to gather statistics for. * * The timer callback will be called when the window expires. */static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb,					   u64 nsecs){	mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs));} static inline void blk_stat_deactivate(struct blk_stat_callback *cb){	timer_delete_sync(&cb->timer);} /** * blk_stat_activate_msecs() - Gather block statistics during a time window in * milliseconds. * @cb: The callback. * @msecs: Number of milliseconds to gather statistics for. * * The timer callback will be called when the window expires. */static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb,					   unsigned int msecs){	mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs));} void blk_rq_stat_add(struct blk_rq_stat *, u64);void blk_rq_stat_sum(struct blk_rq_stat *, struct blk_rq_stat *);void blk_rq_stat_init(struct blk_rq_stat *); #endif