[PATCH 3/9] Introduce context structure needed during checkpointing/restart

Andrey Mirkin
2008-09-03T10:55:26Z

Add functions for context allocation/destroy.
Introduce functions to read/write image.
Introduce image header and object header.

Signed-off-by: Andrey Mirkin <major@openvz.org>
---
cpt/cpt.h | 37 ++++++++++++++++
cpt/cpt_image.h | 63 +++++++++++++++++++++++++++
cpt/sys.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 224 insertions(+), 3 deletions(-)
create mode 100644 cpt/cpt_image.h

diff --git a/cpt/cpt.h b/cpt/cpt.h
index 381a9bf..607ac1b 100644
--- a/cpt/cpt.h
+++ b/cpt/cpt.h
@@ -10,6 +10,8 @@
*
*/

+#include "cpt_image.h"
+
struct cpt_operations
{
struct module * owner;
@@ -17,3 +19,38 @@ struct cpt_operations
int (*restart)(int ctid, int fd, unsigned long flags);
};
extern struct cpt_operations cpt_ops;
+
+#define CPT_CTX_ERROR -1
+#define CPT_CTX_IDLE 0
+#define CPT_CTX_DUMPING 1
+#define CPT_CTX_UNDUMPING 2
+
+typedef struct cpt_context
+{
+ pid_t pid; /* should be changed to ctid later */
+ int ctx_id; /* context id */
+ struct list_head ctx_list;
+ int refcount;
+ int ctx_state;
+ struct semaphore main_sem;
+
+ int errno;
+
+ struct file *file;
+ loff_t current_object;
+
+ struct list_head object_array[CPT_OBJ_MAX];
+
+ int (*write)(const void *addr, size_t count, struct cpt_context *ctx);
+ int (*read)(void *addr, size_t count, struct cpt_context *ctx);
+} cpt_context_t;
+
+extern int debug_level;
+
+#define cpt_printk(lvl, fmt, args...) do { \
+ if (lvl <= debug_level) \
+ printk(fmt, ##args); \
+ } while (0)
+
+#define eprintk(a...) cpt_printk(1, "CPT ERR: " a)
+#define dprintk(a...) cpt_printk(1, "CPT DBG: " a)
diff --git a/cpt/cpt_image.h b/cpt/cpt_image.h
new file mode 100644
index 0000000..3d26229
--- /dev/null
+++ b/cpt/cpt_image.h
@@ -0,0 +1,63 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef __CPT_IMAGE_H_
+#define __CPT_IMAGE_H_ 1
+
+enum _cpt_object_type
+{
+ CPT_OBJ_TASK = 0,
+ CPT_OBJ_MAX,
+ /* The objects above are stored in memory while checkpointing */
+
+ CPT_OBJ_HEAD = 1024,
+};
+
+enum _cpt_content_type {
+ CPT_CONTENT_VOID,
+ CPT_CONTENT_ARRAY,
+ CPT_CONTENT_DATA,
+ CPT_CONTENT_NAME,
+ CPT_CONTENT_REF,
+ CPT_CONTENT_MAX
+};
+
+#define CPT_SIGNATURE0 0x79
+#define CPT_SIGNATURE1 0x1c
+#define CPT_SIGNATURE2 0x01
+#define CPT_SIGNATURE3 0x63
+
+struct cpt_head
+{
+ __u8 cpt_signature[4]; /* Magic number */
+ __u32 cpt_hdrlen; /* Header length */
+ __u16 cpt_image_major; /* Format of this file */
+ __u16 cpt_image_minor; /* Format of this file */
+ __u16 cpt_image_sublevel; /* Format of this file */
+ __u16 cpt_image_extra; /* Format of this file */
+ __u16 cpt_arch; /* Architecture */
+ __u16 cpt_pad1;
+ __u32 cpt_pad2;
+#define CPT_ARCH_I386 0
+ __u64 cpt_time; /* Time */
+} __attribute__ ((aligned (8)));
+
+/* Common object header. */
+struct cpt_object_hdr
+{
+ __u64 cpt_len; /* Size of current chunk of data */
+ __u16 cpt_type; /* Type of object */
+ __u32 cpt_hdrlen; /* Size of header */
+ __u16 cpt_content; /* Content type: array, reference... */
+} __attribute__ ((aligned (8)));
+
+#endif /* __CPT_IMAGE_H_ */
diff --git a/cpt/sys.c b/cpt/sys.c
index 4051286..8334c4c 100644
--- a/cpt/sys.c
+++ b/cpt/sys.c
@@ -13,21 +13,142 @@
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
-#include <linux/notifier.h>
+#include <linux/uaccess.h>
#include <linux/module.h>

#include "cpt.h"
+#include "cpt_image.h"

MODULE_LICENSE("GPL");

+/* Debug level, constant for now */
+int debug_level = 1;
+
+static int file_write(const void *addr, size_t count, struct cpt_context *ctx)
+{
+ mm_segment_t oldfs;
+ ssize_t err = -EBADF;
+ struct file *file = ctx->file;
+
+ oldfs = get_fs(); set_fs(KERNEL_DS);
+ if (file)
+ err = file->f_op->write(file, addr, count, &file->f_pos);
+ set_fs(oldfs);
+ if (err != count)
+ return err >= 0 ? -EIO : err;
+ return 0;
+}
+
+static int file_read(void *addr, size_t count, struct cpt_context *ctx)
+{
+ mm_segment_t oldfs;
+ ssize_t err = -EBADF;
+ struct file *file = ctx->file;
+
+ oldfs = get_fs(); set_fs(KERNEL_DS);
+ if (file)
+ err = file->f_op->read(file, addr, count, &file->f_pos);
+ set_fs(oldfs);
+ if (err != count)
+ return err >= 0 ? -EIO : err;
+ return 0;
+}
+
+struct cpt_context * context_alloc(void)
+{
+ struct cpt_context *ctx;
+ int i;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return NULL;
+
+ init_MUTEX(&ctx->main_sem);
+ ctx->refcount = 1;
+
+ ctx->current_object = -1;
+ ctx->write = file_write;
+ ctx->read = file_read;
+ for (i = 0; i < CPT_OBJ_MAX; i++) {
+ INIT_LIST_HEAD(&ctx->object_array[i]);
+ }
+
+ return ctx;
+}
+
+void context_release(struct cpt_context *ctx)
+{
+ ctx->ctx_state = CPT_CTX_ERROR;
+
+ if (ctx->file)
+ fput(ctx->file);
+ kfree(ctx);
+}
+
+static void context_put(struct cpt_context *ctx)
+{
+ if (!--ctx->refcount)
+ context_release(ctx);
+}
+
static int checkpoint(pid_t pid, int fd, unsigned long flags)
{
- return -ENOSYS;
+ struct file *file;
+ struct cpt_context *ctx;
+ int err;
+
+ err = -EBADF;
+ file = fget(fd);
+ if (!file)
+ goto out;
+
+ err = -ENOMEM;
+ ctx = context_alloc();
+ if (!ctx)
+ goto out_file;
+
+ ctx->file = file;
+ ctx->ctx_state = CPT_CTX_DUMPING;
+
+ /* checkpoint */
+ err = -ENOSYS;
+
+ context_put(ctx);
+
+out_file:
+ fput(file);
+out:
+ return err;
}

static int restart(int ctid, int fd, unsigned long flags)
{
- return -ENOSYS;
+ struct file *file;
+ struct cpt_context *ctx;
+ int err;
+
+ err = -EBADF;
+ file = fget(fd);
+ if (!file)
+ goto out;
+
+ err = -ENOMEM;
+ ctx = context_alloc();
+ if (!ctx)
+ goto out_file;
+
+ ctx->file = file;
+ ctx->ctx_state = CPT_CTX_UNDUMPING;
+
+ /* restart */
+ err = -ENOSYS;
+
+ context_put(ctx);
+
+out_file:
+ fput(file);
+out:
+ return err;
}

static int __init init_cptrst(void)
--
1.5.6