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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef BLK_STAT_H3#define BLK_STAT_H4 5#include <linux/kernel.h>6#include <linux/blkdev.h>7#include <linux/ktime.h>8#include <linux/rcupdate.h>9#include <linux/timer.h>10 11/**12 * struct blk_stat_callback - Block statistics callback.13 *14 * A &struct blk_stat_callback is associated with a &struct request_queue. While15 * @timer is active, that queue's request completion latencies are sorted into16 * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the17 * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked.18 */19struct blk_stat_callback {20 /*21 * @list: RCU list of callbacks for a &struct request_queue.22 */23 struct list_head list;24 25 /**26 * @timer: Timer for the next callback invocation.27 */28 struct timer_list timer;29 30 /**31 * @cpu_stat: Per-cpu statistics buckets.32 */33 struct blk_rq_stat __percpu *cpu_stat;34 35 /**36 * @bucket_fn: Given a request, returns which statistics bucket it37 * should be accounted under. Return -1 for no bucket for this38 * request.39 */40 int (*bucket_fn)(const struct request *);41 42 /**43 * @buckets: Number of statistics buckets.44 */45 unsigned int buckets;46 47 /**48 * @stat: Array of statistics buckets.49 */50 struct blk_rq_stat *stat;51 52 /**53 * @fn: Callback function.54 */55 void (*timer_fn)(struct blk_stat_callback *);56 57 /**58 * @data: Private pointer for the user.59 */60 void *data;61 62 struct rcu_head rcu;63};64 65struct blk_queue_stats *blk_alloc_queue_stats(void);66void blk_free_queue_stats(struct blk_queue_stats *);67 68void blk_stat_add(struct request *rq, u64 now);69 70/* record time/size info in request but not add a callback */71void blk_stat_enable_accounting(struct request_queue *q);72void blk_stat_disable_accounting(struct request_queue *q);73 74/**75 * blk_stat_alloc_callback() - Allocate a block statistics callback.76 * @timer_fn: Timer callback function.77 * @bucket_fn: Bucket callback function.78 * @buckets: Number of statistics buckets.79 * @data: Value for the @data field of the &struct blk_stat_callback.80 *81 * See &struct blk_stat_callback for details on the callback functions.82 *83 * Return: &struct blk_stat_callback on success or NULL on ENOMEM.84 */85struct blk_stat_callback *86blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),87 int (*bucket_fn)(const struct request *),88 unsigned int buckets, void *data);89 90/**91 * blk_stat_add_callback() - Add a block statistics callback to be run on a92 * request queue.93 * @q: The request queue.94 * @cb: The callback.95 *96 * Note that a single &struct blk_stat_callback can only be added to a single97 * &struct request_queue.98 */99void blk_stat_add_callback(struct request_queue *q,100 struct blk_stat_callback *cb);101 102/**103 * blk_stat_remove_callback() - Remove a block statistics callback from a104 * request queue.105 * @q: The request queue.106 * @cb: The callback.107 *108 * When this returns, the callback is not running on any CPUs and will not be109 * called again unless readded.110 */111void blk_stat_remove_callback(struct request_queue *q,112 struct blk_stat_callback *cb);113 114/**115 * blk_stat_free_callback() - Free a block statistics callback.116 * @cb: The callback.117 *118 * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must119 * not be associated with a request queue. I.e., if it was previously added with120 * blk_stat_add_callback(), it must also have been removed since then with121 * blk_stat_remove_callback().122 */123void blk_stat_free_callback(struct blk_stat_callback *cb);124 125/**126 * blk_stat_is_active() - Check if a block statistics callback is currently127 * gathering statistics.128 * @cb: The callback.129 */130static inline bool blk_stat_is_active(struct blk_stat_callback *cb)131{132 return timer_pending(&cb->timer);133}134 135/**136 * blk_stat_activate_nsecs() - Gather block statistics during a time window in137 * nanoseconds.138 * @cb: The callback.139 * @nsecs: Number of nanoseconds to gather statistics for.140 *141 * The timer callback will be called when the window expires.142 */143static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb,144 u64 nsecs)145{146 mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs));147}148 149static inline void blk_stat_deactivate(struct blk_stat_callback *cb)150{151 del_timer_sync(&cb->timer);152}153 154/**155 * blk_stat_activate_msecs() - Gather block statistics during a time window in156 * milliseconds.157 * @cb: The callback.158 * @msecs: Number of milliseconds to gather statistics for.159 *160 * The timer callback will be called when the window expires.161 */162static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb,163 unsigned int msecs)164{165 mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs));166}167 168void blk_rq_stat_add(struct blk_rq_stat *, u64);169void blk_rq_stat_sum(struct blk_rq_stat *, struct blk_rq_stat *);170void blk_rq_stat_init(struct blk_rq_stat *);171 172#endif173