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    Subject[PATCH 03/10] Introduce context structure needed during checkpointing/restart
    Date
    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>
    ---
    checkpoint/checkpoint.h | 40 +++++++++++++++
    checkpoint/cpt_image.h | 63 ++++++++++++++++++++++++
    checkpoint/sys.c | 125 +++++++++++++++++++++++++++++++++++++++++++++-
    3 files changed, 225 insertions(+), 3 deletions(-)
    create mode 100644 checkpoint/cpt_image.h

    diff --git a/checkpoint/checkpoint.h b/checkpoint/checkpoint.h
    index 381a9bf..8ea73f5 100644
    --- a/checkpoint/checkpoint.h
    +++ b/checkpoint/checkpoint.h
    @@ -10,6 +10,8 @@
    *
    */

    +#include "cpt_image.h"
    +
    struct cpt_operations
    {
    struct module * owner;
    @@ -17,3 +19,41 @@ struct cpt_operations
    int (*restart)(int ctid, int fd, unsigned long flags);
    };
    extern struct cpt_operations cpt_ops;
    +
    +enum cpt_ctx_state
    +{
    + CPT_CTX_ERROR = -1,
    + CPT_CTX_IDLE = 0,
    + CPT_CTX_DUMPING,
    + CPT_CTX_UNDUMPING
    +};
    +
    +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/checkpoint/cpt_image.h b/checkpoint/cpt_image.h
    new file mode 100644
    index 0000000..0338dd0
    --- /dev/null
    +++ b/checkpoint/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 */
    +#define CPT_ARCH_I386 0
    + __u16 cpt_pad1;
    + __u32 cpt_pad2;
    + __u64 cpt_time; /* Time */
    +} __attribute__ ((aligned (8)));
    +
    +/* Common object header. */
    +struct cpt_object_hdr
    +{
    + __u64 cpt_len; /* Size of current chunk of data */
    + __u32 cpt_hdrlen; /* Size of header */
    + __u16 cpt_type; /* Type of object */
    + __u16 cpt_content; /* Content type: array, reference... */
    +} __attribute__ ((aligned (8)));
    +
    +#endif /* __CPT_IMAGE_H_ */
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index 010e4eb..a561a06 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -13,21 +13,140 @@
    #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 "checkpoint.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;
    +
    + 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


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