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

[Andrey Mirkin <major@openvz.org>]

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)