[PATCH 2/9] General infrastructure for checkpoint restart

Dave Hansen
2008-10-16T18:17:36Z

Add those interfaces, as well as helpers needed to easily manage the
file format. The code is roughly broken out as follows:

checkpoint/sys.c - user/kernel data transfer, as well as setup of the
checkpoint/restart context (a per-checkpoint data structure for
housekeeping)

checkpoint/checkpoint.c - output wrappers and basic checkpoint handling

checkpoint/restart.c - input wrappers and basic restart handling

Patches to add the per-architecture support as well as the actual
work to do the memory checkpoint follow in subsequent patches.

Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
---

linux-2.6.git-dave/Makefile | 2
linux-2.6.git-dave/checkpoint/Makefile | 2
linux-2.6.git-dave/checkpoint/checkpoint.c | 174 +++++++++++++++++
linux-2.6.git-dave/checkpoint/restart.c | 197 +++++++++++++++++++
linux-2.6.git-dave/checkpoint/sys.c | 219 +++++++++++++++++++++-
linux-2.6.git-dave/fs/read_write.c | 4
linux-2.6.git-dave/include/linux/checkpoint.h | 60 ++++++
linux-2.6.git-dave/include/linux/checkpoint_hdr.h | 75 +++++++
linux-2.6.git-dave/include/linux/magic.h | 3
9 files changed, 728 insertions(+), 8 deletions(-)

diff -puN /dev/null checkpoint/checkpoint.c
--- /dev/null 2008-09-02 09:40:19.000000000 -0700
+++ linux-2.6.git-dave/checkpoint/checkpoint.c 2008-10-16 10:53:34.000000000 -0700
@@ -0,0 +1,174 @@
+/*
+ * Checkpoint logic and helpers
+ *
+ * Copyright (C) 2008 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/version.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/dcache.h>
+#include <linux/mount.h>
+#include <linux/utsname.h>
+#include <linux/magic.h>
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+/**
+ * cr_write_obj - write a record described by a cr_hdr
+ * @ctx: checkpoint context
+ * @h: record descriptor
+ * @buf: record buffer
+ */
+int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf)
+{
+ int ret;
+
+ ret = cr_kwrite(ctx, h, sizeof(*h));
+ if (ret < 0)
+ return ret;
+ return cr_kwrite(ctx, buf, h->len);
+}
+
+/**
+ * cr_write_string - write a string
+ * @ctx: checkpoint context
+ * @str: string pointer
+ * @len: string length
+ */
+int cr_write_string(struct cr_ctx *ctx, char *str, int len)
+{
+ struct cr_hdr h;
+
+ h.type = CR_HDR_STRING;
+ h.len = len;
+ h.parent = 0;
+
+ return cr_write_obj(ctx, &h, str);
+}
+
+/* write the checkpoint header */
+static int cr_write_head(struct cr_ctx *ctx)
+{
+ struct cr_hdr h;
+ struct cr_hdr_head *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ struct new_utsname *uts;
+ struct timeval ktv;
+ int ret;
+
+ h.type = CR_HDR_HEAD;
+ h.len = sizeof(*hh);
+ h.parent = 0;
+
+ do_gettimeofday(&ktv);
+
+ hh->magic = CHECKPOINT_MAGIC_HEAD;
+ hh->major = (LINUX_VERSION_CODE >> 16) & 0xff;
+ hh->minor = (LINUX_VERSION_CODE >> 8) & 0xff;
+ hh->patch = (LINUX_VERSION_CODE) & 0xff;
+
+ hh->rev = CR_VERSION;
+
+ hh->flags = ctx->flags;
+ hh->time = ktv.tv_sec;
+
+ uts = utsname();
+ memcpy(hh->release, uts->release, __NEW_UTS_LEN);
+ memcpy(hh->version, uts->version, __NEW_UTS_LEN);
+ memcpy(hh->machine, uts->machine, __NEW_UTS_LEN);
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+/* write the checkpoint trailer */
+static int cr_write_tail(struct cr_ctx *ctx)
+{
+ struct cr_hdr h;
+ struct cr_hdr_tail *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int ret;
+
+ h.type = CR_HDR_TAIL;
+ h.len = sizeof(*hh);
+ h.parent = 0;
+
+ hh->magic = CHECKPOINT_MAGIC_TAIL;
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+/* dump the task_struct of a given task */
+static int cr_write_task_struct(struct cr_ctx *ctx, struct task_struct *t)
+{
+ struct cr_hdr h;
+ struct cr_hdr_task *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int ret;
+
+ h.type = CR_HDR_TASK;
+ h.len = sizeof(*hh);
+ h.parent = 0;
+
+ hh->state = t->state;
+ hh->exit_state = t->exit_state;
+ hh->exit_code = t->exit_code;
+ hh->exit_signal = t->exit_signal;
+
+ hh->task_comm_len = TASK_COMM_LEN;
+
+ /* FIXME: save remaining relevant task_struct fields */
+
+ ret = cr_write_obj(ctx, &h, hh);
+ cr_hbuf_put(ctx, sizeof(*hh));
+ if (ret < 0)
+ return ret;
+
+ return cr_write_string(ctx, t->comm, TASK_COMM_LEN);
+}
+
+/* dump the entire state of a given task */
+static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
+{
+ int ret ;
+
+ if (t->state == TASK_DEAD) {
+ pr_warning("CR: task may not be in state TASK_DEAD\n");
+ return -EAGAIN;
+ }
+
+ ret = cr_write_task_struct(ctx, t);
+ cr_debug("ret %d\n", ret);
+
+ return ret;
+}
+
+int do_checkpoint(struct cr_ctx *ctx)
+{
+ int ret;
+
+ /* FIX: need to test whether container is checkpointable */
+
+ ret = cr_write_head(ctx);
+ if (ret < 0)
+ goto out;
+ ret = cr_write_task(ctx, current);
+ if (ret < 0)
+ goto out;
+ ret = cr_write_tail(ctx);
+ if (ret < 0)
+ goto out;
+
+ /* on success, return (unique) checkpoint identifier */
+ ret = ctx->crid;
+
+ out:
+ return ret;
+}
diff -puN checkpoint/Makefile~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart checkpoint/Makefile
--- linux-2.6.git/checkpoint/Makefile~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart 2008-10-16 10:53:34.000000000 -0700
+++ linux-2.6.git-dave/checkpoint/Makefile 2008-10-16 10:53:34.000000000 -0700
@@ -2,4 +2,4 @@
# Makefile for linux checkpoint/restart.
#

-obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o
+obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o
diff -puN /dev/null checkpoint/restart.c
--- /dev/null 2008-09-02 09:40:19.000000000 -0700
+++ linux-2.6.git-dave/checkpoint/restart.c 2008-10-16 10:53:34.000000000 -0700
@@ -0,0 +1,197 @@
+/*
+ * Restart logic and helpers
+ *
+ * Copyright (C) 2008 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/version.h>
+#include <linux/sched.h>
+#include <linux/file.h>
+#include <linux/magic.h>
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+/**
+ * cr_read_obj - read a whole record (cr_hdr followed by payload)
+ * @ctx: checkpoint context
+ * @h: record descriptor
+ * @buf: record buffer
+ * @n: available buffer size
+ *
+ * Returns size of payload
+ */
+int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n)
+{
+ int ret;
+
+ ret = cr_kread(ctx, h, sizeof(*h));
+ if (ret < 0)
+ return ret;
+
+ cr_debug("type %d len %d parent %d\n", h->type, h->len, h->parent);
+
+ if (h->len < 0 || h->len > n)
+ return -EINVAL;
+
+ return cr_kread(ctx, buf, h->len);
+}
+
+/**
+ * cr_read_obj_type - read a whole record of expected type
+ * @ctx: checkpoint context
+ * @buf: record buffer
+ * @n: available buffer size
+ * @type: expected record type
+ *
+ * Returns object reference of the parent object
+ */
+int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type)
+{
+ struct cr_hdr h;
+ int ret;
+
+ ret = cr_read_obj(ctx, &h, buf, n);
+ if (ret < 0)
+ return ret;
+
+ ret = -EINVAL;
+ if (h.type == type)
+ ret = h.parent;
+
+ return ret;
+}
+
+/**
+ * cr_read_string - read a string
+ * @ctx: checkpoint context
+ * @str: string buffer
+ * @len: buffer buffer length
+ */
+int cr_read_string(struct cr_ctx *ctx, void *str, int len)
+{
+ return cr_read_obj_type(ctx, str, len, CR_HDR_STRING);
+}
+
+/* read the checkpoint header */
+static int cr_read_head(struct cr_ctx *ctx)
+{
+ struct cr_hdr_head *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int parent, ret = -EINVAL;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_HEAD);
+ if (parent < 0) {
+ ret = parent;
+ goto out;
+ } else if (parent != 0)
+ goto out;
+
+ if (hh->magic != CHECKPOINT_MAGIC_HEAD || hh->rev != CR_VERSION ||
+ hh->major != ((LINUX_VERSION_CODE >> 16) & 0xff) ||
+ hh->minor != ((LINUX_VERSION_CODE >> 8) & 0xff) ||
+ hh->patch != ((LINUX_VERSION_CODE) & 0xff))
+ goto out;
+
+ if (hh->flags & ~CR_CTX_CKPT)
+ goto out;
+
+ ctx->oflags = hh->flags;
+
+ /* FIX: verify compatibility of release, version and machine */
+
+ ret = 0;
+ out:
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+/* read the checkpoint trailer */
+static int cr_read_tail(struct cr_ctx *ctx)
+{
+ struct cr_hdr_tail *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ int parent, ret = -EINVAL;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_TAIL);
+ if (parent < 0) {
+ ret = parent;
+ goto out;
+ } else if (parent != 0)
+ goto out;
+
+ if (hh->magic != CHECKPOINT_MAGIC_TAIL)
+ goto out;
+
+ ret = 0;
+ out:
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+/* read the task_struct into the current task */
+static int cr_read_task_struct(struct cr_ctx *ctx)
+{
+ struct cr_hdr_task *hh = cr_hbuf_get(ctx, sizeof(*hh));
+ struct task_struct *t = current;
+ char *buf;
+ int parent, ret = -EINVAL;
+
+ parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_TASK);
+ if (parent < 0) {
+ ret = parent;
+ goto out;
+ } else if (parent != 0)
+ goto out;
+
+ /* upper limit for task_comm_len to prevent DoS */
+ if (hh->task_comm_len < 0 || hh->task_comm_len > PAGE_SIZE)
+ goto out;
+
+ buf = kmalloc(hh->task_comm_len, GFP_KERNEL);
+ if (!buf)
+ goto out;
+ ret = cr_read_string(ctx, buf, hh->task_comm_len);
+ if (!ret) {
+ /* if t->comm is too long, silently truncate */
+ memset(t->comm, 0, TASK_COMM_LEN);
+ memcpy(t->comm, buf, min(hh->task_comm_len, TASK_COMM_LEN));
+ }
+ kfree(buf);
+
+ /* FIXME: restore remaining relevant task_struct fields */
+ out:
+ cr_hbuf_put(ctx, sizeof(*hh));
+ return ret;
+}
+
+/* read the entire state of the current task */
+static int cr_read_task(struct cr_ctx *ctx)
+{
+ int ret;
+
+ ret = cr_read_task_struct(ctx);
+ cr_debug("ret %d\n", ret);
+
+ return ret;
+}
+
+int do_restart(struct cr_ctx *ctx)
+{
+ int ret;
+
+ ret = cr_read_head(ctx);
+ if (ret < 0)
+ goto out;
+ ret = cr_read_task(ctx);
+ if (ret < 0)
+ goto out;
+ ret = cr_read_tail(ctx);
+ if (ret < 0)
+ goto out;
+
+ /* on success, adjust the return value if needed [TODO] */
+ out:
+ return ret;
+}
diff -puN checkpoint/sys.c~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart checkpoint/sys.c
--- linux-2.6.git/checkpoint/sys.c~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart 2008-10-16 10:53:34.000000000 -0700
+++ linux-2.6.git-dave/checkpoint/sys.c 2008-10-16 10:53:34.000000000 -0700
@@ -10,6 +10,187 @@

#include <linux/sched.h>
#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/uaccess.h>
+#include <linux/capability.h>
+#include <linux/checkpoint.h>
+
+/*
+ * helpers to write/read to/from the image file descriptor
+ *
+ * cr_uwrite() - write a user-space buffer to the checkpoint image
+ * cr_kwrite() - write a kernel-space buffer to the checkpoint image
+ * cr_uread() - read from the checkpoint image to a user-space buffer
+ * cr_kread() - read from the checkpoint image to a kernel-space buffer
+ */
+
+int cr_uwrite(struct cr_ctx *ctx, void *buf, int count)
+{
+ struct file *file = ctx->file;
+ ssize_t nwrite;
+ int nleft;
+
+ for (nleft = count; nleft; nleft -= nwrite) {
+ loff_t pos = file_pos_read(file);
+ nwrite = vfs_write(file, (char __user *) buf, nleft, &pos);
+ file_pos_write(file, pos);
+ if (nwrite <= 0) {
+ if (nwrite == -EAGAIN)
+ nwrite = 0;
+ else
+ return nwrite;
+ }
+ buf += nwrite;
+ }
+
+ ctx->total += count;
+ return 0;
+}
+
+int cr_kwrite(struct cr_ctx *ctx, void *buf, int count)
+{
+ mm_segment_t oldfs;
+ int ret;
+
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = cr_uwrite(ctx, buf, count);
+ set_fs(oldfs);
+
+ return ret;
+}
+
+int cr_uread(struct cr_ctx *ctx, void *buf, int count)
+{
+ struct file *file = ctx->file;
+ ssize_t nread;
+ int nleft;
+
+ for (nleft = count; nleft; nleft -= nread) {
+ loff_t pos = file_pos_read(file);
+ nread = vfs_read(file, (char __user *) buf, nleft, &pos);
+ file_pos_write(file, pos);
+ if (nread <= 0) {
+ if (nread == -EAGAIN)
+ nread = 0;
+ else
+ return nread;
+ }
+ buf += nread;
+ }
+
+ ctx->total += count;
+ return 0;
+}
+
+int cr_kread(struct cr_ctx *ctx, void *buf, int count)
+{
+ mm_segment_t oldfs;
+ int ret;
+
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = cr_uread(ctx, buf, count);
+ set_fs(oldfs);
+
+ return ret;
+}
+
+/*
+ * During checkpoint and restart the code writes outs/reads in data
+ * to/from the chekcpoint image from/to a temporary buffer (ctx->hbuf).
+ * Because operations can be nested, one should call cr_hbuf_get() to
+ * reserve space in the buffer, and then cr_hbuf_put() when no longer
+ * needs that space.
+ */
+
+/*
+ * ctx->hbuf is used to hold headers and data of known (or bound),
+ * static sizes. In some cases, multiple headers may be allocated in
+ * a nested manner. The size should accommodate all headers, nested
+ * or not, on all archs.
+ */
+#define CR_HBUF_TOTAL (8 * 4096)
+
+/**
+ * cr_hbuf_get - reserve space on the hbuf
+ * @ctx: checkpoint context
+ * @n: number of bytes to reserve
+ *
+ * Returns pointer to reserved space
+ */
+void *cr_hbuf_get(struct cr_ctx *ctx, int n)
+{
+ void *ptr;
+
+ /*
+ * Since requests depend on logic and static header sizes (not on
+ * user data), space should always suffice, unless someone either
+ * made a structure bigger or call path deeper than expected.
+ */
+ BUG_ON(ctx->hpos + n > CR_HBUF_TOTAL);
+ ptr = ctx->hbuf + ctx->hpos;
+ ctx->hpos += n;
+ return ptr;
+}
+
+/**
+ * cr_hbuf_put - unreserve space on the hbuf
+ * @ctx: checkpoint context
+ * @n: number of bytes to reserve
+ */
+void cr_hbuf_put(struct cr_ctx *ctx, int n)
+{
+ BUG_ON(ctx->hpos < n);
+ ctx->hpos -= n;
+}
+
+/*
+ * helpers to manage CR contexts: allocated for each checkpoint and/or
+ * restart operation, and persists until the operation is completed.
+ */
+
+/* unique checkpoint identifier (FIXME: should be per-container) */
+static atomic_t cr_ctx_count;
+
+void cr_ctx_free(struct cr_ctx *ctx)
+{
+ if (ctx->file)
+ fput(ctx->file);
+
+ kfree(ctx->hbuf);
+
+ kfree(ctx);
+}
+
+struct cr_ctx *cr_ctx_alloc(pid_t pid, int fd, unsigned long flags)
+{
+ struct cr_ctx *ctx;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ ctx->file = fget(fd);
+ if (!ctx->file) {
+ cr_ctx_free(ctx);
+ return ERR_PTR(-EBADF);
+ }
+
+ ctx->hbuf = kmalloc(CR_HBUF_TOTAL, GFP_KERNEL);
+ if (!ctx->hbuf) {
+ cr_ctx_free(ctx);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ ctx->pid = pid;
+ ctx->flags = flags;
+
+ ctx->crid = atomic_inc_return(&cr_ctx_count);
+
+ return ctx;
+}

/**
* sys_checkpoint - checkpoint a container
@@ -22,9 +203,26 @@
*/
asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
{
- pr_debug("sys_checkpoint not implemented yet\n");
- return -ENOSYS;
+ struct cr_ctx *ctx;
+ int ret;
+
+ /* no flags for now */
+ if (flags)
+ return -EINVAL;
+
+ ctx = cr_ctx_alloc(pid, fd, flags | CR_CTX_CKPT);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ ret = do_checkpoint(ctx);
+
+ if (!ret)
+ ret = ctx->crid;
+
+ cr_ctx_free(ctx);
+ return ret;
}
+
/**
* sys_restart - restart a container
* @crid: checkpoint image identifier
@@ -36,6 +234,19 @@ asmlinkage long sys_checkpoint(pid_t pid
*/
asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
{
- pr_debug("sys_restart not implemented yet\n");
- return -ENOSYS;
+ struct cr_ctx *ctx;
+ int ret;
+
+ /* no flags for now */
+ if (flags)
+ return -EINVAL;
+
+ ctx = cr_ctx_alloc(crid, fd, flags | CR_CTX_RSTR);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ ret = do_restart(ctx);
+
+ cr_ctx_free(ctx);
+ return ret;
}
diff -puN fs/read_write.c~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart fs/read_write.c
--- linux-2.6.git/fs/read_write.c~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart 2008-10-16 10:53:34.000000000 -0700
+++ linux-2.6.git-dave/fs/read_write.c 2008-10-16 10:53:34.000000000 -0700
@@ -324,12 +324,12 @@ ssize_t vfs_write(struct file *file, con

EXPORT_SYMBOL(vfs_write);

-static inline loff_t file_pos_read(struct file *file)
+inline loff_t file_pos_read(struct file *file)
{
return file->f_pos;
}

-static inline void file_pos_write(struct file *file, loff_t pos)
+inline void file_pos_write(struct file *file, loff_t pos)
{
file->f_pos = pos;
}
diff -puN /dev/null include/linux/checkpoint.h
--- /dev/null 2008-09-02 09:40:19.000000000 -0700
+++ linux-2.6.git-dave/include/linux/checkpoint.h 2008-10-16 10:53:34.000000000 -0700
@@ -0,0 +1,60 @@
+#ifndef _CHECKPOINT_CKPT_H_
+#define _CHECKPOINT_CKPT_H_
+/*
+ * Generic container checkpoint-restart
+ *
+ * Copyright (C) 2008 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#define CR_VERSION 1
+
+struct cr_ctx {
+ pid_t pid; /* container identifier */
+ int crid; /* unique checkpoint id */
+
+ unsigned long flags;
+ unsigned long oflags; /* restart: old flags */
+
+ struct file *file;
+ int total; /* total read/written */
+
+ void *hbuf; /* temporary buffer for headers */
+ int hpos; /* position in headers buffer */
+};
+
+/* cr_ctx: flags */
+#define CR_CTX_CKPT 0x1
+#define CR_CTX_RSTR 0x2
+
+extern int cr_uwrite(struct cr_ctx *ctx, void *buf, int count);
+extern int cr_kwrite(struct cr_ctx *ctx, void *buf, int count);
+extern int cr_uread(struct cr_ctx *ctx, void *buf, int count);
+extern int cr_kread(struct cr_ctx *ctx, void *buf, int count);
+
+extern void *cr_hbuf_get(struct cr_ctx *ctx, int n);
+extern void cr_hbuf_put(struct cr_ctx *ctx, int n);
+
+struct cr_hdr;
+
+extern int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf);
+extern int cr_write_string(struct cr_ctx *ctx, char *str, int len);
+
+extern int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
+extern int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
+extern int cr_read_string(struct cr_ctx *ctx, void *str, int len);
+
+extern int do_checkpoint(struct cr_ctx *ctx);
+extern int do_restart(struct cr_ctx *ctx);
+
+/* there are from fs/read_write.c, not exported otherwise in a header */
+extern loff_t file_pos_read(struct file *file);
+extern void file_pos_write(struct file *file, loff_t pos);
+
+#define cr_debug(fmt, args...) \
+ pr_debug("[CR:%s] " fmt, __func__, ## args)
+
+#endif /* _CHECKPOINT_CKPT_H_ */
diff -puN /dev/null include/linux/checkpoint_hdr.h
--- /dev/null 2008-09-02 09:40:19.000000000 -0700
+++ linux-2.6.git-dave/include/linux/checkpoint_hdr.h 2008-10-16 10:53:34.000000000 -0700
@@ -0,0 +1,75 @@
+#ifndef _CHECKPOINT_CKPT_HDR_H_
+#define _CHECKPOINT_CKPT_HDR_H_
+/*
+ * Generic container checkpoint-restart
+ *
+ * Copyright (C) 2008 Oren Laadan
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/types.h>
+#include <linux/utsname.h>
+
+/*
+ * To maintain compatibility between 32-bit and 64-bit architecture flavors,
+ * keep data 64-bit aligned: use padding for structure members, and use
+ * __attribute__ ((aligned (8))) for the entire structure.
+ */
+
+/* records: generic header */
+
+struct cr_hdr {
+ __s16 type;
+ __s16 len;
+ __u32 parent;
+};
+
+/* header types */
+enum {
+ CR_HDR_HEAD = 1,
+ CR_HDR_STRING,
+
+ CR_HDR_TASK = 101,
+ CR_HDR_THREAD,
+ CR_HDR_CPU,
+
+ CR_HDR_MM = 201,
+ CR_HDR_VMA,
+ CR_HDR_MM_CONTEXT,
+
+ CR_HDR_TAIL = 5001
+};
+
+struct cr_hdr_head {
+ __u64 magic;
+
+ __u16 major;
+ __u16 minor;
+ __u16 patch;
+ __u16 rev;
+
+ __u64 time; /* when checkpoint taken */
+ __u64 flags; /* checkpoint options */
+
+ char release[__NEW_UTS_LEN];
+ char version[__NEW_UTS_LEN];
+ char machine[__NEW_UTS_LEN];
+} __attribute__((aligned(8)));
+
+struct cr_hdr_tail {
+ __u64 magic;
+} __attribute__((aligned(8)));
+
+struct cr_hdr_task {
+ __u32 state;
+ __u32 exit_state;
+ __u32 exit_code;
+ __u32 exit_signal;
+
+ __s32 task_comm_len;
+} __attribute__((aligned(8)));
+
+#endif /* _CHECKPOINT_CKPT_HDR_H_ */
diff -puN include/linux/magic.h~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart include/linux/magic.h
--- linux-2.6.git/include/linux/magic.h~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart 2008-10-16 10:53:34.000000000 -0700
+++ linux-2.6.git-dave/include/linux/magic.h 2008-10-16 10:53:34.000000000 -0700
@@ -46,4 +46,7 @@
#define FUTEXFS_SUPER_MAGIC 0xBAD1DEA
#define INOTIFYFS_SUPER_MAGIC 0x2BAD1DEA

+#define CHECKPOINT_MAGIC_HEAD 0x00feed0cc0a2d200LL
+#define CHECKPOINT_MAGIC_TAIL 0x002d2a0cc0deef00LL
+
#endif /* __LINUX_MAGIC_H__ */
diff -puN Makefile~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart Makefile
--- linux-2.6.git/Makefile~v6_PATCH_2_9_General_infrastructure_for_checkpoint_restart 2008-10-16 10:53:34.000000000 -0700
+++ linux-2.6.git-dave/Makefile 2008-10-16 10:53:34.000000000 -0700
@@ -619,7 +619,7 @@ export mod_strip_cmd

ifeq ($(KBUILD_EXTMOD),)
-core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/
+core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/ checkpoint/

vmlinux-dirs := $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
$(core-y) $(core-m) $(drivers-y) $(drivers-m) \
_