[PATCH 1/4] Virtualization/containers: introduction

[Kirill Korotaev <dev@openvz.org>]

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Hello,

I tried to take into account all the comments from you guys (thanks a 
lot for them!) and prepared a new version of virtualization patches. I 
will send only 4 patches today, just not to overflow everyone and keep 
it clear/tidy/possible to review.

This patch introduces some abstract container kernel structure and a 
number of operations on it.

The important properties of the proposed container implementation:
- each container has unique ID in the system
- each process in the kernel can belong to one container only
- effective container pointer (econtainer()) is used on the task to 
avoid insertion of additional argument "container" to all functions 
where it is required.
- kernel compilation with disabled virtualization should result in old 
good linux kernel

Patches following this one will be used for virtualization of the kernel 
resources based on this container infrastructure, including those VPID 
patches I sent before. Every virtualized resource can be given separate 
config option if needed (just give me to know if it is desired).

Signed-Off-By: Kirill Korotaev <dev@openvz.org>

Kirill

P.S. I understand that this virtualization spam can be unintersting for 
some of you, just give me to know if you want to be removed from CC.

P.P.S. All patches are against 2.6.16-rc2-git2 and compile when 
virtualization=n.


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--- ./include/linux/container.h.vpsinfo	2006-02-06 22:35:36.000000000 +0300
+++ ./include/linux/container.h	2006-02-07 00:52:57.000000000 +0300
@@ -0,0 +1,59 @@
+#ifndef __LINUX_CONTAINER_H__
+#define __LINUX_CONTAINER_H__
+
+#include <linux/config.h>
+#include <asm/types.h>
+#include <asm/atomic.h>
+
+struct task_struct;
+
+struct container {
+	u32 id;
+	struct task_struct *init_task;
+	atomic_t refcnt;
+};
+
+extern struct container init_container;
+
+#ifdef CONFIG_CONTAINER
+
+static inline struct container *get_container(struct container *cont)
+{
+	atomic_inc(&cont->refcnt);
+	return cont;
+}
+
+static inline void put_container(struct container *cont)
+{
+	atomic_dec(&container->refcnt);
+}
+
+#include <linux/sched.h>
+#include <asm/current.h>
+
+static inline struct container *set_econtainer(struct container *cont)
+{
+	struct container *ret;
+
+	ret = current->econtainer;
+	current->econtainer = cont;
+	return ret;
+}
+
+#define econtainer()		(current->econtainer)
+
+extern void init_containers(void);
+
+#else	/* CONFIG_CONTAINER */
+
+#define get_container(cont)	(NULL)
+#define put_container(cont)	do { } while (0)
+
+#define set_econtainer(cont)	((struct container *)NULL)
+#define econtainer()		(NULL)
+
+#define init_containers()	do { } while (0)
+
+#endif	/* CONFIG_CONTAINER */
+
+#endif
--- ./include/linux/init_task.h.vpsinfo	2006-01-03 06:21:10.000000000 +0300
+++ ./include/linux/init_task.h	2006-02-07 00:52:52.000000000 +0300
@@ -3,6 +3,7 @@
 
 #include <linux/file.h>
 #include <linux/rcupdate.h>
+#include <linux/container.h>
 
 #define INIT_FDTABLE \
 {							\
@@ -131,5 +132,7 @@ extern struct group_info init_groups;
 	LIST_HEAD_INIT(cpu_timers[2]),					\
 }
 
+#define INIT_CONTAINER(cont)						\
+	.refcnt		= ATOMIC_INIT(1)
 
 #endif
--- ./include/linux/sched.h.vpsinfo	2006-02-06 22:15:05.000000000 +0300
+++ ./include/linux/sched.h	2006-02-07 00:53:32.000000000 +0300
@@ -687,6 +687,7 @@ static inline void prefetch_stack(struct
 
 struct audit_context;		/* See audit.c */
 struct mempolicy;
+struct container;
 
 struct task_struct {
 	volatile long state;	/* -1 unrunnable, 0 runnable, >0 stopped */
@@ -846,6 +847,11 @@ struct task_struct {
 
 	struct io_context *io_context;
 
+#ifdef CONFIG_CONTAINER
+	struct container *container;
+	struct container *econtainer;	/* effective container */
+#endif
+
 	unsigned long ptrace_message;
 	siginfo_t *last_siginfo; /* For ptrace use.  */
 /*
--- ./init/main.c.vpsinfo	2006-02-06 22:15:06.000000000 +0300
+++ ./init/main.c	2006-02-07 00:46:12.000000000 +0300
@@ -47,6 +47,7 @@
 #include <linux/rmap.h>
 #include <linux/mempolicy.h>
 #include <linux/key.h>
+#include <linux/container.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -603,6 +604,8 @@ static void __init do_initcalls(void)
  */
 static void __init do_basic_setup(void)
 {
+	init_containers();
+
 	/* drivers will send hotplug events */
 	init_workqueues();
 	usermodehelper_init();
--- ./kernel/Makefile.vpsinfo	2006-02-06 22:15:06.000000000 +0300
+++ ./kernel/Makefile	2006-02-07 00:46:12.000000000 +0300
@@ -34,6 +34,7 @@ obj-$(CONFIG_DETECT_SOFTLOCKUP) += softl
 obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
 obj-$(CONFIG_SECCOMP) += seccomp.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
+obj-$(CONFIG_CONTAINER) += container.c
 
 ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
--- ./kernel/container.c.vpsinfo	2006-02-07 00:01:21.000000000 +0300
+++ ./kernel/container.c	2006-02-07 00:46:12.000000000 +0300
@@ -0,0 +1,16 @@
+#include <linux/container.h>
+
+/*
+ * Initial container.
+ *
+ * All tasks and other resources initially belong to it
+ */
+struct container init_container = INIT_CONTAINER(init_container);
+
+EXPORT_SYMBOL(init_container);
+
+void init_containers(void)
+{
+	/* remember who is init in container */
+	init_container.init_task = child_reaper;
+}
--- ./kernel/exit.c.vpsinfo	2006-02-06 22:15:06.000000000 +0300
+++ ./kernel/exit.c	2006-02-07 00:46:12.000000000 +0300
@@ -31,6 +31,7 @@
 #include <linux/signal.h>
 #include <linux/cn_proc.h>
 #include <linux/mutex.h>
+#include <linux/container.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -107,6 +108,7 @@ repeat: 
 	spin_unlock(&p->proc_lock);
 	proc_pid_flush(proc_dentry);
 	release_thread(p);
+	put_container(p->container);
 	put_task_struct(p);
 
 	p = leader;
--- ./kernel/fork.c.vpsinfo	2006-02-06 22:15:06.000000000 +0300
+++ ./kernel/fork.c	2006-02-07 00:46:12.000000000 +0300
@@ -44,6 +44,7 @@
 #include <linux/rmap.h>
 #include <linux/acct.h>
 #include <linux/cn_proc.h>
+#include <linux/container.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -1132,6 +1133,7 @@ static task_t *copy_process(unsigned lon
 	p->ioprio = current->ioprio;
 
 	SET_LINKS(p);
+	(void)get_container(p->container);
 	if (unlikely(p->ptrace & PT_PTRACED))
 		__ptrace_link(p, current->parent);