[PATCH 2/9] Make checkpoint/restart functionality modular

Andrey Mirkin
2008-09-03T10:56:35Z

A config option CONFIG_CHECKPOINT is introduced.
New structure cpt_operations is introduced to store pointers to
checkpoint/restart functions from module.

Signed-off-by: Andrey Mirkin <major@openvz.org>
---
cpt/Kconfig | 7 +++++++
cpt/Makefile | 4 ++++
cpt/cpt.h | 19 +++++++++++++++++++
cpt/sys.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
cpt/sys_core.c | 29 +++++++++++++++++++++++++++--
init/Kconfig | 2 ++
6 files changed, 107 insertions(+), 2 deletions(-)
create mode 100644 cpt/Kconfig
create mode 100644 cpt/cpt.h
create mode 100644 cpt/sys.c

diff --git a/cpt/Kconfig b/cpt/Kconfig
new file mode 100644
index 0000000..b9bc72d
--- /dev/null
+++ b/cpt/Kconfig
@@ -0,0 +1,7 @@
+config CHECKPOINT
+ tristate "Checkpoint & restart for containers"
+ depends on EXPERIMENTAL
+ default n
+ help
+ This option adds module "cptrst", which allow to save a running
+ container to a file and restart it later using this image file.
diff --git a/cpt/Makefile b/cpt/Makefile
index 2276fb1..bfe75d5 100644
--- a/cpt/Makefile
+++ b/cpt/Makefile
@@ -1 +1,5 @@
obj-y += sys_core.o
+
+obj-$(CONFIG_CHECKPOINT) += cptrst.o
+
+cptrst-objs := sys.o
diff --git a/cpt/cpt.h b/cpt/cpt.h
new file mode 100644
index 0000000..381a9bf
--- /dev/null
+++ b/cpt/cpt.h
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2008 Parallels, Inc.
+ *
+ * Author: Andrey Mirkin <major@openvz.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ */
+
+struct cpt_operations
+{
+ struct module * owner;
+ int (*checkpoint)(pid_t pid, int fd, unsigned long flags);
+ int (*restart)(int ctid, int fd, unsigned long flags);
+};
+extern struct cpt_operations cpt_ops;
diff --git a/cpt/sys.c b/cpt/sys.c
new file mode 100644
index 0000000..4051286
--- /dev/null
+++ b/cpt/sys.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2008 Parallels, Inc.
+ *
+ * Author: Andrey Mirkin <major@openvz.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/notifier.h>
+#include <linux/module.h>
+
+#include "cpt.h"
+
+MODULE_LICENSE("GPL");
+
+static int checkpoint(pid_t pid, int fd, unsigned long flags)
+{
+ return -ENOSYS;
+}
+
+static int restart(int ctid, int fd, unsigned long flags)
+{
+ return -ENOSYS;
+}
+
+static int __init init_cptrst(void)
+{
+ cpt_ops.owner = THIS_MODULE;
+ cpt_ops.checkpoint = checkpoint;
+ cpt_ops.restart = restart;
+ return 0;
+}
+module_init(init_cptrst);
+
+static void __exit exit_cptrst(void)
+{
+ cpt_ops.checkpoint = NULL;
+ cpt_ops.restart = NULL;
+ cpt_ops.owner = NULL;
+}
+module_exit(exit_cptrst);
diff --git a/cpt/sys_core.c b/cpt/sys_core.c
index 1a97fb6..5dd1191 100644
--- a/cpt/sys_core.c
+++ b/cpt/sys_core.c
@@ -13,6 +13,13 @@
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
+#include <linux/notifier.h>
+#include <linux/module.h>
+
+#include "cpt.h"
+
+struct cpt_operations cpt_ops = { NULL, NULL, NULL };
+EXPORT_SYMBOL(cpt_ops);

/**
* sys_checkpoint - checkpoint a container from outside
@@ -23,7 +30,16 @@
*/
asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
{
- return -ENOSYS;
+ int ret;
+
+ ret = -ENOSYS;
+
+ if (try_module_get(cpt_ops.owner)) {
+ if (cpt_ops.checkpoint)
+ ret = cpt_ops.checkpoint(pid, fd, flags);
+ module_put(cpt_ops.owner);
+ }
+ return ret;
}

/**
@@ -34,5 +50,14 @@ asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
*/
asmlinkage long sys_restart(int ctid, int fd, unsigned long flags)
{
- return -ENOSYS;
+ int ret;
+
+ ret = -ENOSYS;
+
+ if (try_module_get(cpt_ops.owner)) {
+ if (cpt_ops.restart)
+ ret = cpt_ops.restart(ctid, fd, flags);
+ module_put(cpt_ops.owner);
+ }
+ return ret;
}
diff --git a/init/Kconfig b/init/Kconfig
index 4bd4b0c..d29ed21 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -344,6 +344,8 @@ config CGROUP_FREEZER
Provides a way to freeze and unfreeze all tasks in a
cgroup

+source "cpt/Kconfig"
+
config FAIR_GROUP_SCHED
bool "Group scheduling for SCHED_OTHER"
depends on GROUP_SCHED
--
1.5.6