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14a6e2eb7d
In our test of iocost, we encountered some list add/del corruptions of
inner_walk list in ioc_timer_fn.
The reason can be described as follows:
cpu 0 cpu 1
ioc_qos_write ioc_qos_write
ioc = q_to_ioc(queue);
if (!ioc) {
ioc = kzalloc();
ioc = q_to_ioc(queue);
if (!ioc) {
ioc = kzalloc();
...
rq_qos_add(q, rqos);
}
...
rq_qos_add(q, rqos);
...
}
When the io.cost.qos file is written by two cpus concurrently, rq_qos may
be added to one disk twice. In that case, there will be two iocs enabled
and running on one disk. They own different iocgs on their active list. In
the ioc_timer_fn function, because of the iocgs from two iocs have the
same root iocg, the root iocg's walk_list may be overwritten by each other
and this leads to list add/del corruptions in building or destroying the
inner_walk list.
And so far, the blk-rq-qos framework works in case that one instance for
one type rq_qos per queue by default. This patch make this explicit and
also fix the crash above.
Signed-off-by: Jinke Han <hanjinke.666@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220720093616.70584-1-hanjinke.666@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
237 lines
5.7 KiB
C
237 lines
5.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef RQ_QOS_H
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#define RQ_QOS_H
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#include <linux/kernel.h>
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#include <linux/blkdev.h>
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#include <linux/blk_types.h>
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#include <linux/atomic.h>
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#include <linux/wait.h>
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#include <linux/blk-mq.h>
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#include "blk-mq-debugfs.h"
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struct blk_mq_debugfs_attr;
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enum rq_qos_id {
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RQ_QOS_WBT,
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RQ_QOS_LATENCY,
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RQ_QOS_COST,
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RQ_QOS_IOPRIO,
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};
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struct rq_wait {
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wait_queue_head_t wait;
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atomic_t inflight;
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};
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struct rq_qos {
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struct rq_qos_ops *ops;
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struct request_queue *q;
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enum rq_qos_id id;
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struct rq_qos *next;
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#ifdef CONFIG_BLK_DEBUG_FS
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struct dentry *debugfs_dir;
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#endif
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};
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struct rq_qos_ops {
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void (*throttle)(struct rq_qos *, struct bio *);
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void (*track)(struct rq_qos *, struct request *, struct bio *);
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void (*merge)(struct rq_qos *, struct request *, struct bio *);
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void (*issue)(struct rq_qos *, struct request *);
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void (*requeue)(struct rq_qos *, struct request *);
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void (*done)(struct rq_qos *, struct request *);
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void (*done_bio)(struct rq_qos *, struct bio *);
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void (*cleanup)(struct rq_qos *, struct bio *);
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void (*queue_depth_changed)(struct rq_qos *);
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void (*exit)(struct rq_qos *);
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const struct blk_mq_debugfs_attr *debugfs_attrs;
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};
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struct rq_depth {
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unsigned int max_depth;
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int scale_step;
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bool scaled_max;
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unsigned int queue_depth;
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unsigned int default_depth;
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};
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static inline struct rq_qos *rq_qos_id(struct request_queue *q,
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enum rq_qos_id id)
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{
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struct rq_qos *rqos;
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for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
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if (rqos->id == id)
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break;
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}
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return rqos;
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}
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static inline struct rq_qos *wbt_rq_qos(struct request_queue *q)
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{
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return rq_qos_id(q, RQ_QOS_WBT);
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}
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static inline struct rq_qos *blkcg_rq_qos(struct request_queue *q)
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{
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return rq_qos_id(q, RQ_QOS_LATENCY);
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}
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static inline void rq_wait_init(struct rq_wait *rq_wait)
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{
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atomic_set(&rq_wait->inflight, 0);
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init_waitqueue_head(&rq_wait->wait);
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}
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static inline int rq_qos_add(struct request_queue *q, struct rq_qos *rqos)
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{
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/*
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* No IO can be in-flight when adding rqos, so freeze queue, which
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* is fine since we only support rq_qos for blk-mq queue.
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*
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* Reuse ->queue_lock for protecting against other concurrent
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* rq_qos adding/deleting
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*/
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blk_mq_freeze_queue(q);
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spin_lock_irq(&q->queue_lock);
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if (rq_qos_id(q, rqos->id))
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goto ebusy;
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rqos->next = q->rq_qos;
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q->rq_qos = rqos;
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spin_unlock_irq(&q->queue_lock);
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blk_mq_unfreeze_queue(q);
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if (rqos->ops->debugfs_attrs) {
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mutex_lock(&q->debugfs_mutex);
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blk_mq_debugfs_register_rqos(rqos);
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mutex_unlock(&q->debugfs_mutex);
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}
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return 0;
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ebusy:
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spin_unlock_irq(&q->queue_lock);
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blk_mq_unfreeze_queue(q);
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return -EBUSY;
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}
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static inline void rq_qos_del(struct request_queue *q, struct rq_qos *rqos)
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{
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struct rq_qos **cur;
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/*
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* See comment in rq_qos_add() about freezing queue & using
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* ->queue_lock.
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*/
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blk_mq_freeze_queue(q);
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spin_lock_irq(&q->queue_lock);
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for (cur = &q->rq_qos; *cur; cur = &(*cur)->next) {
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if (*cur == rqos) {
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*cur = rqos->next;
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break;
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}
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}
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spin_unlock_irq(&q->queue_lock);
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blk_mq_unfreeze_queue(q);
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mutex_lock(&q->debugfs_mutex);
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blk_mq_debugfs_unregister_rqos(rqos);
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mutex_unlock(&q->debugfs_mutex);
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}
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typedef bool (acquire_inflight_cb_t)(struct rq_wait *rqw, void *private_data);
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typedef void (cleanup_cb_t)(struct rq_wait *rqw, void *private_data);
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void rq_qos_wait(struct rq_wait *rqw, void *private_data,
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acquire_inflight_cb_t *acquire_inflight_cb,
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cleanup_cb_t *cleanup_cb);
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bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit);
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bool rq_depth_scale_up(struct rq_depth *rqd);
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bool rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle);
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bool rq_depth_calc_max_depth(struct rq_depth *rqd);
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void __rq_qos_cleanup(struct rq_qos *rqos, struct bio *bio);
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void __rq_qos_done(struct rq_qos *rqos, struct request *rq);
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void __rq_qos_issue(struct rq_qos *rqos, struct request *rq);
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void __rq_qos_requeue(struct rq_qos *rqos, struct request *rq);
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void __rq_qos_throttle(struct rq_qos *rqos, struct bio *bio);
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void __rq_qos_track(struct rq_qos *rqos, struct request *rq, struct bio *bio);
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void __rq_qos_merge(struct rq_qos *rqos, struct request *rq, struct bio *bio);
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void __rq_qos_done_bio(struct rq_qos *rqos, struct bio *bio);
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void __rq_qos_queue_depth_changed(struct rq_qos *rqos);
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static inline void rq_qos_cleanup(struct request_queue *q, struct bio *bio)
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{
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if (q->rq_qos)
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__rq_qos_cleanup(q->rq_qos, bio);
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}
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static inline void rq_qos_done(struct request_queue *q, struct request *rq)
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{
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if (q->rq_qos)
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__rq_qos_done(q->rq_qos, rq);
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}
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static inline void rq_qos_issue(struct request_queue *q, struct request *rq)
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{
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if (q->rq_qos)
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__rq_qos_issue(q->rq_qos, rq);
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}
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static inline void rq_qos_requeue(struct request_queue *q, struct request *rq)
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{
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if (q->rq_qos)
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__rq_qos_requeue(q->rq_qos, rq);
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}
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static inline void rq_qos_done_bio(struct bio *bio)
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{
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if (bio->bi_bdev && (bio_flagged(bio, BIO_QOS_THROTTLED) ||
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bio_flagged(bio, BIO_QOS_MERGED))) {
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struct request_queue *q = bdev_get_queue(bio->bi_bdev);
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if (q->rq_qos)
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__rq_qos_done_bio(q->rq_qos, bio);
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}
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}
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static inline void rq_qos_throttle(struct request_queue *q, struct bio *bio)
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{
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if (q->rq_qos) {
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bio_set_flag(bio, BIO_QOS_THROTTLED);
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__rq_qos_throttle(q->rq_qos, bio);
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}
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}
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static inline void rq_qos_track(struct request_queue *q, struct request *rq,
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struct bio *bio)
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{
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if (q->rq_qos)
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__rq_qos_track(q->rq_qos, rq, bio);
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}
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static inline void rq_qos_merge(struct request_queue *q, struct request *rq,
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struct bio *bio)
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{
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if (q->rq_qos) {
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bio_set_flag(bio, BIO_QOS_MERGED);
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__rq_qos_merge(q->rq_qos, rq, bio);
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}
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}
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static inline void rq_qos_queue_depth_changed(struct request_queue *q)
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{
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if (q->rq_qos)
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__rq_qos_queue_depth_changed(q->rq_qos);
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}
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void rq_qos_exit(struct request_queue *);
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#endif
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