[RFC][PATCH 7/7] Account for the number of files opened within container

[Pavel Emelianov <xemul@sw.ru>]

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Simple again - increment usage counter at file open and
decrement at file close. Reject opening if limit is hit.

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diff -upr linux-2.6.20.orig/fs/Makefile linux-2.6.20-0/fs/Makefile
--- linux-2.6.20.orig/fs/Makefile	2007-02-04 21:44:54.000000000 +0300
+++ linux-2.6.20-0/fs/Makefile	2007-03-06 13:33:28.000000000 +0300
@@ -19,6 +19,8 @@ else
 obj-y +=	no-block.o
 endif
 
+obj-$(CONFIG_FILES_CONTAINER)	+= numfiles_container.o
+
 obj-$(CONFIG_INOTIFY)		+= inotify.o
 obj-$(CONFIG_INOTIFY_USER)	+= inotify_user.o
 obj-$(CONFIG_EPOLL)		+= eventpoll.o
diff -upr linux-2.6.20.orig/fs/file_table.c linux-2.6.20-0/fs/file_table.c
--- linux-2.6.20.orig/fs/file_table.c	2007-02-04 21:44:54.000000000 +0300
+++ linux-2.6.20-0/fs/file_table.c	2007-03-06 13:33:28.000000000 +0300
@@ -21,6 +21,7 @@
 #include <linux/fsnotify.h>
 #include <linux/sysctl.h>
 #include <linux/percpu_counter.h>
+#include <linux/numfiles_container.h>
 
 #include <asm/atomic.h>
 
@@ -42,6 +43,7 @@ static inline void file_free_rcu(struct 
 
 static inline void file_free(struct file *f)
 {
+	container_file_uncharge(f);
 	percpu_counter_dec(&nr_files);
 	call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
 }
@@ -109,6 +111,10 @@ struct file *get_empty_filp(void)
 
 	percpu_counter_inc(&nr_files);
 	memset(f, 0, sizeof(*f));
+
+	if (container_file_charge(f))
+		goto fail_charge;
+
 	if (security_file_alloc(f))
 		goto fail_sec;
 
@@ -132,7 +138,10 @@ over:
 	goto fail;
 
 fail_sec:
-	file_free(f);
+	container_file_uncharge(f);
+fail_charge:
+	percpu_counter_dec(&nr_files);
+	kmem_cache_free(filp_cachep, f);
 fail:
 	return NULL;
 }
diff -upr linux-2.6.20.orig/fs/numfiles_container.c linux-2.6.20-0/fs/numfiles_container.c
--- linux-2.6.20.orig/fs/numfiles_container.c	2007-03-06 13:39:17.000000000 +0300
+++ linux-2.6.20-0/fs/numfiles_container.c	2007-03-06 13:33:28.000000000 +0300
@@ -0,0 +1,152 @@
+/*
+ * Numfiles accounting container
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ *
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ */
+
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/res_counter.h>
+#include <linux/numfiles_container.h>
+
+static struct container_subsys numfiles_subsys;
+
+struct files_container {
+	struct res_counter res;
+	struct container_subsys_state css;
+};
+
+static inline struct files_container *numfiles_from_cont(struct container *cnt)
+{
+	return container_of(container_subsys_state(cnt, &numfiles_subsys),
+			struct files_container, css);
+}
+
+int container_file_charge(struct file *file)
+{
+	struct files_container *fc;
+
+	rcu_read_lock();
+	fc = numfiles_from_cont(task_container(current, &numfiles_subsys));
+	css_get_current(&fc->css);
+	rcu_read_unlock();
+
+	if (res_counter_charge(&fc->res, 1)) {
+		css_put(&fc->css);
+		return -ENOMEM;
+	}
+
+	file->f_cont = fc;
+	return 0;
+}
+
+void container_file_uncharge(struct file *file)
+{
+	struct files_container *fc;
+
+	fc = file->f_cont;
+	res_counter_uncharge(&fc->res, 1);
+	css_put(&fc->css);
+}
+
+static int numfiles_create(struct container_subsys *ss, struct container *cont)
+{
+	struct files_container *fc;
+
+	fc = kzalloc(sizeof(struct files_container), GFP_KERNEL);
+	if (fc == NULL)
+		return -ENOMEM;
+
+	res_counter_init(&fc->res);
+	cont->subsys[numfiles_subsys.subsys_id] = &fc->css;
+	return 0;
+}
+
+static void numfiles_destroy(struct container_subsys *ss,
+		struct container *cont)
+{
+	kfree(numfiles_from_cont(cont));
+}
+
+
+static ssize_t numfiles_read(struct container *cont, struct cftype *cft,
+		struct file *file, char __user *userbuf,
+		size_t nbytes, loff_t *ppos)
+{
+	return res_counter_read(&numfiles_from_cont(cont)->res, cft->private,
+			userbuf, nbytes, ppos);
+}
+
+static ssize_t numfiles_write(struct container *cont, struct cftype *cft,
+		struct file *file, const char __user *userbuf,
+		size_t nbytes, loff_t *ppos)
+{
+	return res_counter_write(&numfiles_from_cont(cont)->res, cft->private,
+			userbuf, nbytes, ppos);
+}
+
+
+static struct cftype numfiles_usage = {
+	.name = "numfiles_usage",
+	.private = RES_USAGE,
+	.read = numfiles_read,
+};
+
+static struct cftype numfiles_limit = {
+	.name = "numfiles_limit",
+	.private = RES_LIMIT,
+	.read = numfiles_read,
+	.write = numfiles_write,
+};
+
+static struct cftype numfiles_failcnt = {
+	.name = "numfiles_failcnt",
+	.private = RES_FAILCNT,
+	.read = numfiles_read,
+};
+
+static int numfiles_populate(struct container_subsys *ss,
+		struct container *cont)
+{
+	int rc;
+
+	if ((rc = container_add_file(cont, &numfiles_usage)) < 0)
+		return rc;
+	if ((rc = container_add_file(cont, &numfiles_failcnt)) < 0)
+		return rc;
+	if ((rc = container_add_file(cont, &numfiles_limit)) < 0)
+		return rc;
+
+	return 0;
+}
+
+static struct files_container init_files_container;
+
+static __init int numfiles_create_early(struct container_subsys *ss,
+		struct container *cont)
+{
+	struct files_container *np;
+
+	np = &init_files_container;
+	res_counter_init(&np->res);
+	cont->subsys[numfiles_subsys.subsys_id] = &np->css;
+	ss->create = numfiles_create;
+	return 0;
+}
+
+static struct container_subsys numfiles_subsys = {
+	.name = "numfiles",
+	.create = numfiles_create_early,
+	.destroy = numfiles_destroy,
+	.populate = numfiles_populate,
+};
+
+void __init container_numfiles_init_early(void)
+{
+	container_register_subsys(&numfiles_subsys);
+}
+
diff -upr linux-2.6.20.orig/include/linux/fs.h linux-2.6.20-0/include/linux/fs.h
--- linux-2.6.20.orig/include/linux/fs.h	2007-03-06 13:33:28.000000000 +0300
+++ linux-2.6.20-0/include/linux/fs.h	2007-03-06 13:33:28.000000000 +0300
@@ -739,6 +739,9 @@ struct file {
 	spinlock_t		f_ep_lock;
 #endif /* #ifdef CONFIG_EPOLL */
 	struct address_space	*f_mapping;
+#ifdef CONFIG_FILES_CONTAINER
+	struct files_container	*f_cont;
+#endif
 };
 extern spinlock_t files_lock;
 #define file_list_lock() spin_lock(&files_lock);
diff -upr linux-2.6.20.orig/include/linux/numfiles_container.h linux-2.6.20-0/include/linux/numfiles_container.h
--- linux-2.6.20.orig/include/linux/numfiles_container.h	2007-03-06 13:39:17.000000000 +0300
+++ linux-2.6.20-0/include/linux/numfiles_container.h	2007-03-06 13:33:28.000000000 +0300
@@ -0,0 +1,33 @@
+#ifndef __NUMFILES_CONTAINER_H__
+#define __NUMFILES_CONTAINER_H__
+/*
+ * Numfiles container
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ *
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ */
+
+#ifdef CONFIG_FILES_CONTAINER
+int container_file_charge(struct file *file);
+void container_file_uncharge(struct file *file);
+
+void container_numfiles_init_early(void);
+#else
+static inline int container_file_charge(struct file *file)
+{
+	return 0;
+}
+
+static inline void container_file_uncharge(struct file *file)
+{
+}
+
+static inline void container_numfiles_init_early(void)
+{
+}
+#endif
+
+#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 +265,12 @@ config CPUSETS
 	help
 	  Provides the-number-of-tasks accounting container
 
+config FILES_CONTAINER
+	bool "Numfiles accounting container"
+	select RESOURCE_COUNTERS
+	help
+	  Provides the-number-of-files accounting container
+
 config SYSFS_DEPRECATED
 	bool "Create deprecated sysfs files"
 	default y
diff -upr linux-2.6.20.orig/kernel/container.c linux-2.6.20-0/kernel/container.c
--- linux-2.6.20.orig/kernel/container.c	2007-03-06 13:33:28.000000000 +0300
+++ linux-2.6.20-0/kernel/container.c	2007-03-06 13:35:48.000000000 +0300
@@ -60,6 +60,7 @@
 
 #include <linux/rss_container.h>
 #include <linux/numproc_container.h>
+#include <linux/numfiles_container.h>
 
 #define CONTAINER_SUPER_MAGIC		0x27e0eb
 
@@ -1721,6 +1725,7 @@ int __init container_init_early(void)
 
 	container_rss_init_early();
 	container_numproc_init_early();
+	container_numfiles_init_early();
 
 	return 0;
 }