/*
   * 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/slab.h>

  #include <linux/res_counter.h>
  #include <linux/uaccess.h>

  #include <linux/mm.h>

  
  void res_counter_init(struct res_counter *counter)
  {
  	spin_lock_init(&counter->lock);

  	counter->limit = (unsigned long long)LLONG_MAX;

  }
  
  int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
  {
  	if (counter->usage + val > counter->limit) {
  		counter->failcnt++;
  		return -ENOMEM;
  	}
  
  	counter->usage += val;

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

  	return 0;
  }
  
  int res_counter_charge(struct res_counter *counter, unsigned long val)
  {
  	int ret;
  	unsigned long flags;
  
  	spin_lock_irqsave(&counter->lock, flags);
  	ret = res_counter_charge_locked(counter, val);
  	spin_unlock_irqrestore(&counter->lock, flags);
  	return ret;
  }
  
  void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
  {
  	if (WARN_ON(counter->usage < val))
  		val = counter->usage;
  
  	counter->usage -= val;
  }
  
  void res_counter_uncharge(struct res_counter *counter, unsigned long val)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&counter->lock, flags);
  	res_counter_uncharge_locked(counter, val);
  	spin_unlock_irqrestore(&counter->lock, flags);
  }

  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;
  	};
  
  	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);
  }

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

  int res_counter_memparse_write_strategy(const char *buf,
  					unsigned long long *res)

  {

  	char *end;
  	/* FIXME - make memparse() take const char* args */
  	*res = memparse((char *)buf, &end);
  	if (*end != '\0')
  		return -EINVAL;

  	*res = PAGE_ALIGN(*res);
  	return 0;
  }

  int res_counter_write(struct res_counter *counter, int member,
  		      const char *buf, write_strategy_fn write_strategy)
  {
  	char *end;
  	unsigned long flags;
  	unsigned long long tmp, *val;

  	if (write_strategy) {

  		if (write_strategy(buf, &tmp))
  			return -EINVAL;

  	} else {
  		tmp = simple_strtoull(buf, &end, 10);
  		if (*end != '\0')

  			return -EINVAL;

  	}
  	spin_lock_irqsave(&counter->lock, flags);

  	val = res_counter_member(counter, member);
  	*val = tmp;

  	spin_unlock_irqrestore(&counter->lock, flags);

  	return 0;

  }