#include "blk-rq-qos.h"

  /*
   * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded,
   * false if 'v' + 1 would be bigger than 'below'.
   */

  static bool atomic_inc_below(atomic_t *v, unsigned int below)

  {

  	unsigned int cur = atomic_read(v);

  
  	for (;;) {

  		unsigned int old;

  
  		if (cur >= below)
  			return false;
  		old = atomic_cmpxchg(v, cur, cur + 1);
  		if (old == cur)
  			break;
  		cur = old;
  	}
  
  	return true;
  }

  bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit)

  {
  	return atomic_inc_below(&rq_wait->inflight, limit);
  }

  void rq_qos_cleanup(struct request_queue *q, struct bio *bio)

  {
  	struct rq_qos *rqos;
  
  	for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->cleanup)

  			rqos->ops->cleanup(rqos, bio);

  	}
  }
  
  void rq_qos_done(struct request_queue *q, struct request *rq)
  {
  	struct rq_qos *rqos;
  
  	for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->done)
  			rqos->ops->done(rqos, rq);
  	}
  }
  
  void rq_qos_issue(struct request_queue *q, struct request *rq)
  {
  	struct rq_qos *rqos;
  
  	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->issue)
  			rqos->ops->issue(rqos, rq);
  	}
  }
  
  void rq_qos_requeue(struct request_queue *q, struct request *rq)
  {
  	struct rq_qos *rqos;
  
  	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->requeue)
  			rqos->ops->requeue(rqos, rq);
  	}
  }

  void rq_qos_throttle(struct request_queue *q, struct bio *bio,
  		     spinlock_t *lock)

  {
  	struct rq_qos *rqos;

  
  	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->throttle)

  			rqos->ops->throttle(rqos, bio, lock);
  	}
  }
  
  void rq_qos_track(struct request_queue *q, struct request *rq, struct bio *bio)
  {
  	struct rq_qos *rqos;
  
  	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->track)
  			rqos->ops->track(rqos, rq, bio);

  	}

  }

  void rq_qos_done_bio(struct request_queue *q, struct bio *bio)
  {
  	struct rq_qos *rqos;
  
  	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
  		if (rqos->ops->done_bio)
  			rqos->ops->done_bio(rqos, bio);
  	}
  }

  /*
   * Return true, if we can't increase the depth further by scaling
   */
  bool rq_depth_calc_max_depth(struct rq_depth *rqd)
  {
  	unsigned int depth;
  	bool ret = false;
  
  	/*
  	 * For QD=1 devices, this is a special case. It's important for those
  	 * to have one request ready when one completes, so force a depth of
  	 * 2 for those devices. On the backend, it'll be a depth of 1 anyway,
  	 * since the device can't have more than that in flight. If we're
  	 * scaling down, then keep a setting of 1/1/1.
  	 */
  	if (rqd->queue_depth == 1) {
  		if (rqd->scale_step > 0)
  			rqd->max_depth = 1;
  		else {
  			rqd->max_depth = 2;
  			ret = true;
  		}
  	} else {
  		/*
  		 * scale_step == 0 is our default state. If we have suffered
  		 * latency spikes, step will be > 0, and we shrink the
  		 * allowed write depths. If step is < 0, we're only doing
  		 * writes, and we allow a temporarily higher depth to
  		 * increase performance.
  		 */
  		depth = min_t(unsigned int, rqd->default_depth,
  			      rqd->queue_depth);
  		if (rqd->scale_step > 0)
  			depth = 1 + ((depth - 1) >> min(31, rqd->scale_step));
  		else if (rqd->scale_step < 0) {
  			unsigned int maxd = 3 * rqd->queue_depth / 4;
  
  			depth = 1 + ((depth - 1) << -rqd->scale_step);
  			if (depth > maxd) {
  				depth = maxd;
  				ret = true;
  			}
  		}
  
  		rqd->max_depth = depth;
  	}
  
  	return ret;
  }
  
  void rq_depth_scale_up(struct rq_depth *rqd)
  {
  	/*
  	 * Hit max in previous round, stop here
  	 */
  	if (rqd->scaled_max)
  		return;
  
  	rqd->scale_step--;
  
  	rqd->scaled_max = rq_depth_calc_max_depth(rqd);
  }
  
  /*
   * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we
   * had a latency violation.
   */
  void rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle)
  {
  	/*
  	 * Stop scaling down when we've hit the limit. This also prevents
  	 * ->scale_step from going to crazy values, if the device can't
  	 * keep up.
  	 */
  	if (rqd->max_depth == 1)
  		return;
  
  	if (rqd->scale_step < 0 && hard_throttle)
  		rqd->scale_step = 0;
  	else
  		rqd->scale_step++;
  
  	rqd->scaled_max = false;
  	rq_depth_calc_max_depth(rqd);
  }
  
  void rq_qos_exit(struct request_queue *q)
  {
  	while (q->rq_qos) {
  		struct rq_qos *rqos = q->rq_qos;
  		q->rq_qos = rqos->next;
  		rqos->ops->exit(rqos);
  	}
  }