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    SubjectRe: [PATCH 3/9] Introduce context structure needed during checkpointing/restart
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    On Wednesday 03 September 2008 16:29 Matthieu Fertré wrote:
    > Andrey Mirkin a écrit :
    > > 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
    >
    > Maybe you can define an enum here instead.
    >
    > > +
    > > +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;
    >
    > It will be more clear that ctx_state refers to it.

    Thanks for the idea with enum, I'll fix it in next version.

    Regards,
    Andrey

    >
    > > + 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)
    --
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