/*
   * resource cgroups
   *
   * Copyright 2007 OpenVZ SWsoft Inc
   *
   * Author: Pavel Emelianov <xemul@openvz.org>
   *
   */
  
  #include <linux/types.h>
  #include <linux/parser.h>
  #include <linux/fs.h>
  #include <linux/res_counter.h>
  #include <linux/uaccess.h>

  #include <linux/mm.h>

  void res_counter_init(struct res_counter *counter, struct res_counter *parent)

  {
  	spin_lock_init(&counter->lock);

  	counter->limit = RES_COUNTER_MAX;
  	counter->soft_limit = RES_COUNTER_MAX;

  	counter->parent = parent;

  }

  static u64 res_counter_uncharge_locked(struct res_counter *counter,
  				       unsigned long val)
  {
  	if (WARN_ON(counter->usage < val))
  		val = counter->usage;
  
  	counter->usage -= val;
  	return counter->usage;
  }
  
  static int res_counter_charge_locked(struct res_counter *counter,
  				     unsigned long val, bool force)

  {

  	int ret = 0;

  	if (counter->usage + val > counter->limit) {
  		counter->failcnt++;

  		ret = -ENOMEM;
  		if (!force)
  			return ret;

  	}
  
  	counter->usage += val;

  	if (counter->usage > counter->max_usage)

  		counter->max_usage = counter->usage;

  	return ret;

  }

  static int __res_counter_charge(struct res_counter *counter, unsigned long val,
  				struct res_counter **limit_fail_at, bool force)

  {

  	int ret, r;

  	unsigned long flags;

  	struct res_counter *c, *u;

  	r = ret = 0;

  	*limit_fail_at = NULL;
  	local_irq_save(flags);
  	for (c = counter; c != NULL; c = c->parent) {
  		spin_lock(&c->lock);

  		r = res_counter_charge_locked(c, val, force);

  		spin_unlock(&c->lock);

  		if (r < 0 && !ret) {
  			ret = r;

  			*limit_fail_at = c;

  			if (!force)
  				break;

  		}
  	}

  
  	if (ret < 0 && !force) {
  		for (u = counter; u != c; u = u->parent) {
  			spin_lock(&u->lock);
  			res_counter_uncharge_locked(u, val);
  			spin_unlock(&u->lock);
  		}

  	}

  	local_irq_restore(flags);

  	return ret;
  }

  int res_counter_charge(struct res_counter *counter, unsigned long val,
  			struct res_counter **limit_fail_at)
  {
  	return __res_counter_charge(counter, val, limit_fail_at, false);
  }

  int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
  			      struct res_counter **limit_fail_at)
  {

  	return __res_counter_charge(counter, val, limit_fail_at, true);

  }

  u64 res_counter_uncharge_until(struct res_counter *counter,
  			       struct res_counter *top,
  			       unsigned long val)

  {
  	unsigned long flags;

  	struct res_counter *c;

  	u64 ret = 0;

  	local_irq_save(flags);

  	for (c = counter; c != top; c = c->parent) {

  		u64 r;

  		spin_lock(&c->lock);

  		r = res_counter_uncharge_locked(c, val);
  		if (c == counter)
  			ret = r;

  		spin_unlock(&c->lock);
  	}
  	local_irq_restore(flags);

  	return ret;

  }

  u64 res_counter_uncharge(struct res_counter *counter, unsigned long val)

  {

  	return res_counter_uncharge_until(counter, NULL, val);

  }

  static inline unsigned long long *
  res_counter_member(struct res_counter *counter, int member)

  {
  	switch (member) {
  	case RES_USAGE:
  		return &counter->usage;

  	case RES_MAX_USAGE:
  		return &counter->max_usage;

  	case RES_LIMIT:
  		return &counter->limit;
  	case RES_FAILCNT:
  		return &counter->failcnt;

  	case RES_SOFT_LIMIT:
  		return &counter->soft_limit;

  	};
  
  	BUG();
  	return NULL;
  }
  
  ssize_t res_counter_read(struct res_counter *counter, int member,

  		const char __user *userbuf, size_t nbytes, loff_t *pos,
  		int (*read_strategy)(unsigned long long val, char *st_buf))

  {

  	unsigned long long *val;

  	char buf[64], *s;
  
  	s = buf;
  	val = res_counter_member(counter, member);

  	if (read_strategy)
  		s += read_strategy(*val, s);
  	else
  		s += sprintf(s, "%llu
  ", *val);

  	return simple_read_from_buffer((void __user *)userbuf, nbytes,
  			pos, buf, s - buf);
  }

  #if BITS_PER_LONG == 32
  u64 res_counter_read_u64(struct res_counter *counter, int member)
  {
  	unsigned long flags;
  	u64 ret;
  
  	spin_lock_irqsave(&counter->lock, flags);
  	ret = *res_counter_member(counter, member);
  	spin_unlock_irqrestore(&counter->lock, flags);
  
  	return ret;
  }
  #else

  u64 res_counter_read_u64(struct res_counter *counter, int member)
  {
  	return *res_counter_member(counter, member);
  }

  #endif

  int res_counter_memparse_write_strategy(const char *buf,

  					unsigned long long *resp)

  {

  	char *end;

  	unsigned long long res;

  	/* return RES_COUNTER_MAX(unlimited) if "-1" is specified */

  	if (*buf == '-') {

  		res = simple_strtoull(buf + 1, &end, 10);
  		if (res != 1 || *end != '\0')

  			return -EINVAL;

  		*resp = RES_COUNTER_MAX;

  		return 0;
  	}

  	res = memparse(buf, &end);

  	if (*end != '\0')
  		return -EINVAL;

  	if (PAGE_ALIGN(res) >= res)
  		res = PAGE_ALIGN(res);

  	else

  		res = RES_COUNTER_MAX;
  
  	*resp = res;

  	return 0;
  }