[RFC][PATCH 1/7] Resource counters

[Pavel Emelianov <xemul@sw.ru>]

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Introduce generic structures and routines for
resource accounting.

Each resource accounting container is supposed to
aggregate it, container_subsystem_state and its
resource-specific members within.

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diff -upr linux-2.6.20.orig/include/linux/res_counter.h linux-2.6.20-0/include/linux/res_counter.h
--- linux-2.6.20.orig/include/linux/res_counter.h	2007-03-06 13:39:17.000000000 +0300
+++ linux-2.6.20-0/include/linux/res_counter.h	2007-03-06 13:33:28.000000000 +0300
@@ -0,0 +1,83 @@
+#ifndef __RES_COUNTER_H__
+#define __RES_COUNTER_H__
+/*
+ * resource counters
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ *
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ */
+
+#include <linux/container.h>
+
+struct res_counter {
+	unsigned long usage;
+	unsigned long limit;
+	unsigned long failcnt;
+	spinlock_t lock;
+};
+
+enum {
+	RES_USAGE,
+	RES_LIMIT,
+	RES_FAILCNT,
+};
+
+ssize_t res_counter_read(struct res_counter *cnt, int member,
+		const char __user *buf, size_t nbytes, loff_t *pos);
+ssize_t res_counter_write(struct res_counter *cnt, int member,
+		const char __user *buf, size_t nbytes, loff_t *pos);
+
+static inline void res_counter_init(struct res_counter *cnt)
+{
+	spin_lock_init(&cnt->lock);
+	cnt->limit = (unsigned long)LONG_MAX;
+}
+
+static inline int res_counter_charge_locked(struct res_counter *cnt,
+		unsigned long val)
+{
+	if (cnt->usage <= cnt->limit - val) {
+		cnt->usage += val;
+		return 0;
+	}
+
+	cnt->failcnt++;
+	return -ENOMEM;
+}
+
+static inline int res_counter_charge(struct res_counter *cnt,
+		unsigned long val)
+{
+	int ret;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	ret = res_counter_charge_locked(cnt, val);
+	spin_unlock_irqrestore(&cnt->lock, flags);
+	return ret;
+}
+
+static inline void res_counter_uncharge_locked(struct res_counter *cnt,
+		unsigned long val)
+{
+	if (unlikely(cnt->usage < val)) {
+		WARN_ON(1);
+		val = cnt->usage;
+	}
+
+	cnt->usage -= val;
+}
+
+static inline void res_counter_uncharge(struct res_counter *cnt,
+		unsigned long val)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	res_counter_uncharge_locked(cnt, val);
+	spin_unlock_irqrestore(&cnt->lock, flags);
+}
+
+#endif
diff -upr linux-2.6.20.orig/init/Kconfig linux-2.6.20-0/init/Kconfig
--- linux-2.6.20.orig/init/Kconfig	2007-03-06 13:33:28.000000000 +0300
+++ linux-2.6.20-0/init/Kconfig	2007-03-06 13:33:28.000000000 +0300
@@ -265,6 +265,10 @@ config CPUSETS
 
 	  Say N if unsure.
 
+config RESOURCE_COUNTERS
+	bool
+	select CONTAINERS
+
 config SYSFS_DEPRECATED
 	bool "Create deprecated sysfs files"
 	default y
diff -upr linux-2.6.20.orig/kernel/Makefile linux-2.6.20-0/kernel/Makefile
--- linux-2.6.20.orig/kernel/Makefile	2007-03-06 13:33:28.000000000 +0300
+++ linux-2.6.20-0/kernel/Makefile	2007-03-06 13:33:28.000000000 +0300
@@ -51,6 +51,7 @@ obj-$(CONFIG_RELAY) += relay.o
 obj-$(CONFIG_UTS_NS) += utsname.o
 obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
 obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
+obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o
 
 ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff -upr linux-2.6.20.orig/kernel/res_counter.c linux-2.6.20-0/kernel/res_counter.c
--- linux-2.6.20.orig/kernel/res_counter.c	2007-03-06 13:39:17.000000000 +0300
+++ linux-2.6.20-0/kernel/res_counter.c	2007-03-06 13:33:28.000000000 +0300
@@ -0,0 +1,72 @@
+/*
+ * resource containers
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ *
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ */
+
+#include <linux/parser.h>
+#include <linux/fs.h>
+#include <linux/res_counter.h>
+#include <asm/uaccess.h>
+
+static inline unsigned long *res_counter_member(struct res_counter *cnt, int member)
+{
+	switch (member) {
+	case RES_USAGE:
+		return &cnt->usage;
+	case RES_LIMIT:
+		return &cnt->limit;
+	case RES_FAILCNT:
+		return &cnt->failcnt;
+	};
+
+	BUG();
+	return NULL;
+}
+
+ssize_t res_counter_read(struct res_counter *cnt, int member, 
+		const char __user *userbuf, size_t nbytes, loff_t *pos)
+{
+	unsigned long *val;
+	char buf[64], *s;
+
+	s = buf;
+	val = res_counter_member(cnt, member);
+	s += sprintf(s, "%lu\n", *val);
+	return simple_read_from_buffer((void __user *)userbuf, nbytes,
+			pos, buf, s - buf);
+}
+
+ssize_t res_counter_write(struct res_counter *cnt, int member,
+		const char __user *userbuf, size_t nbytes, loff_t *pos)
+{
+	int ret;
+	char *buf, *end;
+	unsigned long tmp, *val;
+
+	buf = kmalloc(nbytes + 1, GFP_KERNEL);
+	ret = -ENOMEM;
+	if (buf == NULL)
+		goto out;
+
+	buf[nbytes] = 0;
+	ret = -EFAULT;
+	if (copy_from_user(buf, userbuf, nbytes))
+		goto out_free;
+
+	ret = -EINVAL;
+	tmp = simple_strtoul(buf, &end, 10);
+	if (*end != '\0')
+		goto out_free;
+
+	val = res_counter_member(cnt, member);
+	*val = tmp;
+	ret = nbytes;
+out_free:
+	kfree(buf);
+out:
+	return ret;
+}