Re: [PATCH] Preserve hibenate-system-image on startup

[Nigel Cunningham]

Hi.

We've had this feature in Suspend2 for a couple of years and I can
confirm that the approach works, provided that the on-disk filesystem
remains unchanged throughout this. (Useful mainly for kiosks etc).

This is not to say that I've reviewed the code below for correctness.

Regards,

Nigel

On Sun, 2005-07-17 at 16:26, Hiroyuki Machida wrote:
> We are now investigating fast startup/shutdown using
> 2.6 kernel PM functions.
> 
> An attached patch enables kernel to preserve system image
> on startup, to implement "Snapshot boot".Majordomo@xxxxxxxxxxxxxxx wrote:
> Conventionally system image will be broken after startup.
> 
> Snapshot boot uses un-hibernate from a permanent system image for
> startup. During shutdown, does a conventional shutdown without
> saving a system image.
> 
> We'll explain concept and initial work at OLS. So if you have
> interest, we can talk with you at Ottawa.
> 
> Thanks,
> Hiroyuki Machida
> 
> ---
> 
> This patch enables preserving swsuspend system image over boot cycle, 
> against 2.6.12
> 
> Signed-off-by: Hiroyui Machida <machida@xxxxxxxxxx> for CELF
> 
> -----------------
> Index: alp-linux--dev-2-6-12--1.7/kernel/power/Kconfig
> ===================================================================
> --- alp-linux--dev-2-6-12--1.7.orig/kernel/power/Kconfig	2005-07-15 14:59:20.000000000 -0400
> +++ alp-linux--dev-2-6-12--1.7/kernel/power/Kconfig	2005-07-16 00:43:31.420000000 -0400
> @@ -84,6 +84,20 @@
>  	  suspended image to. It will simply pick the first available swap 
>  	  device.
>  
> +config PRESERVE_SWSUSP_IMAGE
> +	bool "Preserve swsuspend image"
> +	depends on SOFTWARE_SUSPEND
> +	default n
> +	---help---
> +	  Useally boot with swsup destories the swsusp image.
> +	  This function enables to preserve swsup image over boot cycle. 
> +	  Default behavior is not chaged even this configuration turned on.
> +
> +	  To preseve swsusp image, specify following option to command line;
> +
> +		prsv-img
> +
> +
>  config DEFERRED_RESUME
>  	bool "Deferred resume"
>  	depends on PM
> Index: alp-linux--dev-2-6-12--1.7/kernel/power/disk.c
> ===================================================================
> --- alp-linux--dev-2-6-12--1.7.orig/kernel/power/disk.c	2005-07-16 00:43:02.990000000 -0400
> +++ alp-linux--dev-2-6-12--1.7/kernel/power/disk.c	2005-07-16 01:01:42.220000000 -0400
> @@ -29,10 +29,29 @@
>  extern void swsusp_close(void);
>  extern int swsusp_resume(void);
>  extern int swsusp_free(void);
> +extern void dump_pagedir_nosave(void);
>  #ifdef	CONFIG_SAFE_SUSPEND
>  extern int suspend_remount(void);
>  extern int resume_remount(void);
>  #endif
> +#ifdef CONFIG_PRESERVE_SWSUSP_IMAGE
> +extern int preserve_swsusp_image;
> +extern dev_t swsusp_resume_device_nosave __nosavedata;
> +extern int swsusp_swap_rdonly(dev_t);
> +extern int swsusp_swap_off(dev_t);
> +#else
> +#define preserve_swsusp_image 0
> +#define swsusp_resume_device_nosave 0
> +static inline int swsusp_swap_rdonly(dev_t dev)
> +{
> +	return 0;
> +}
> +static inline int swsusp_swap_off(dev_t dev)
> +{
> +	return 0;
> +}
> +#endif
> +
>  
> 
>  static int noresume = 0;
> @@ -135,6 +154,26 @@
>  	pm_restore_console();
>  }
>  
> +#ifdef CONFIG_PRESERVE_SWSUSP_IMAGE
> +void finish_in_resume(void)
> +{
> +	device_resume();
> +	platform_finish();
> +	enable_nonboot_cpus();
> +	thaw_processes();
> +	if (preserve_swsusp_image) {
> +		swsusp_swap_off(swsusp_resume_device_nosave);
> +	}
> +	pm_restore_console();
> +}
> +#else
> +void finish_in_resume(void)
> +{
> +	finish();
> +}
> +#endif
> +
> +
>  extern atomic_t on_suspend;   /* See refrigerator() */
>  
>  static int prepare_processes(void)
> @@ -234,8 +273,15 @@
>  		error = swsusp_write();
>  		if (!error)
>  			power_down(pm_disk_mode);
> -	} else
> +	} else  {
>  		pr_debug("PM: Image restored successfully.\n");
> +		if (preserve_swsusp_image) {
> +			swsusp_swap_rdonly(swsusp_resume_device_nosave);
> +		}
> +		swsusp_free();
> +		finish_in_resume();
> +		return 0;
> +	}
>  	swsusp_free();
>   Done:
>  	finish();
> Index: alp-linux--dev-2-6-12--1.7/kernel/power/swsusp.c
> ===================================================================
> --- alp-linux--dev-2-6-12--1.7.orig/kernel/power/swsusp.c	2005-07-16 00:43:03.000000000 -0400
> +++ alp-linux--dev-2-6-12--1.7/kernel/power/swsusp.c	2005-07-16 00:56:22.170000000 -0400
> @@ -128,6 +128,11 @@
>  
>  static struct swsusp_info swsusp_info;
>  
> +#ifdef CONFIG_PRESERVE_SWSUSP_IMAGE
> +dev_t swsusp_resume_device_nosave __nosavedata;
> +struct swsusp_header swsusp_header_nosave __nosavedata ;
> +#endif
> +
>  /*
>   * XXX: We try to keep some more pages free so that I/O operations succeed
>   * without paging. Might this be more?
> @@ -139,6 +144,24 @@
>  #define PAGES_FOR_IO	512
>  #endif
>  
> +#ifdef CONFIG_PRESERVE_SWSUSP_IMAGE
> +int preserve_swsusp_image=0;
> +static  int __init preserve_swsusp_image_setup(char *str)
> +{
> +	if (*str)
> +		return 0;
> +	preserve_swsusp_image = 1;
> +	return 1;
> +}
> +#else
> +static  int __init preserve_swsusp_image_setup(char *str)
> +{
> +	return 0;
> +}
> +#endif
> +
> +__setup("prsv-img", preserve_swsusp_image_setup);
> +
>  /*
>   * Saving part...
>   */
> @@ -1250,6 +1273,53 @@
>  	return error;
>  }
>  
> +#ifdef CONFIG_PRESERVE_SWSUSP_IMAGE
> +/**
> + *	mark_swapfiles - Revert swap signature
> + *	
> + *	Assumed that swsusp_header holds correct data 
> + *	and rw_swap_page_sync() works
> + */
> +int mark_swsusp(dev_t dev)
> +{
> +	int	error;
> +
> +	resume_bdev = open_by_devnum(dev, FMODE_WRITE);
> +	if (!IS_ERR(resume_bdev)) {
> +		set_blocksize(resume_bdev, PAGE_SIZE);
> +		error = bio_write_page(0, &swsusp_header_nosave);
> +		blkdev_put(resume_bdev);
> +	} else
> +		error = PTR_ERR(resume_bdev);
> +
> +	if (!error)
> +		pr_debug("swsusp: Mark swsusp again\n");
> +	else
> +		pr_debug("swsusp: Error %d marking swsusp\n", error);
> +	return error;
> +}
> +
> +inline static void update_swsusp_header(void)
> +{
> +	swsusp_header_nosave=swsusp_header;
> +}
> +
> +inline static void update_swsusp_device(void)
> +{
> +	swsusp_resume_device_nosave = swsusp_resume_device;
> +}
> +#else
> +inline static void update_swsusp_header(void)
> +{
> +	;
> +}
> +
> +inline static void update_swsusp_device(void)
> +{
> +	;
> +}
> +#endif
> +
>  static int check_sig(void)
>  {
>  	int error;
> @@ -1258,6 +1328,7 @@
>  	if ((error = bio_read_page(0, &swsusp_header)))
>  		return error;
>  	if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
> +		update_swsusp_header();
>  		memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
>  
>  		/*
> @@ -1412,6 +1483,7 @@
>  		pr_debug("swsusp: Resume From Partition %d:%d\n",
>  			 MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
>  	}
> +	update_swsusp_device();
>  
>  	resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
>  	if (!IS_ERR(resume_bdev)) {
> Index: alp-linux--dev-2-6-12--1.7/mm/swapfile.c
> ===================================================================
> --- alp-linux--dev-2-6-12--1.7.orig/mm/swapfile.c	2005-07-15 10:34:54.000000000 -0400
> +++ alp-linux--dev-2-6-12--1.7/mm/swapfile.c	2005-07-16 00:43:31.000000000 -0400
> @@ -1065,6 +1065,186 @@
>  }
>  #endif
>  
> +#ifdef CONFIG_PRESERVE_SWSUSP_IMAGE
> +extern int mark_swsusp(dev_t);
> +
> +#ifdef DEBUG
> +extern void cons_write(char *);
> +
> +#undef pr_debug
> +#define pr_debug(fmt,arg...) \
> +        do {    \
> +		char __cw_buf[64]; \
> +		__cw_buf[63]='\0'; \
> +                snprintf(__cw_buf, 63, fmt,##arg);   \
> +                cons_write(__cw_buf);   \
> +        } while (0)
> +#endif	/*DEBUG*/
> +
> +/**
> + *  find_swapdev_info - Find swap block device info, currently used
> + *
> + */
> +
> +static struct swap_info_struct *find_swapdev_info(dev_t dev,
> +					int *p_prev, int *p_type)
> +{
> +	int prev, type;
> +	struct inode *inode;
> +	struct swap_info_struct * si = NULL;
> +
> +	prev = -1;
> +	for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
> +		si = swap_info + type;
> +		pr_debug("P:0x%8.8x, TYPE:0x%8.8x\n", (int)si, type);
> +		if (si->flags & SWP_USED) {
> +			inode = si->swap_file->f_mapping->host;
> +			if (S_ISBLK(inode->i_mode)) {
> +				pr_debug("INODE: 0x%8.8x:0x%8.8x\n", 
> +					dev, 
> +					MKDEV(imajor(inode), iminor(inode)));
> +				if (dev == MKDEV(imajor(inode), iminor(inode)))
> +					break;
> +			}
> +		}
> +		prev = type;
> +	}
> +
> +	if (type<0) {
> +		si = 0;
> +	}
> +	*p_type = type;
> +	*p_prev = prev;
> +	return si;
> +}
> +
> +/**
> + * swsusp_swap_rdonly - Find Swap device for swsusp and mark ReadOnly
> + *
> + */
> +int swsusp_swap_rdonly(dev_t resume_dev)
> +{
> +	struct swap_info_struct * si = NULL;
> +	int prev;
> +	int type;
> +	int found=0;
> +
> +	swap_list_lock();
> +
> +	si = find_swapdev_info(resume_dev, &prev, &type);
> +	if (si) {
> +		si->flags &= ~SWP_WRITEOK;
> +		found = 1;
> +	}
> +	swap_list_unlock();
> +	return found;
> +
> +}
> +
> +/**
> + * swsusp_swpoff -  Turn off swap and set signature for swsusp image
> + *
> + */
> +int swsusp_swap_off(dev_t resume_dev)
> +{
> +	struct swap_info_struct * si = NULL;
> +	unsigned short *swap_map;
> +	int i;
> +	int type, prev;
> +	struct block_device *bdev;
> +	int err = 0;
> +
> +	swap_list_lock();
> +
> +	si = find_swapdev_info(resume_dev, &prev, &type);
> +
> +	/* swap area for swsusp image is not writable */
> +	if ((!si) || (si->flags & SWP_WRITEOK)) {
> +		err = -EINVAL;
> +		swap_list_unlock();
> +		goto out;
> +	}
> +
> +	if (!security_vm_enough_memory(si->pages)) {
> +		vm_unacct_memory(si->pages);
> +	} else {
> +		err = -ENOMEM;
> +		si->flags |= SWP_WRITEOK;
> +		swap_list_unlock();
> +		goto out;
> +	}
> +
> +	pr_debug("swsusp_swapoff:inuse_pages:%ld\n", si->inuse_pages);
> +	pr_debug("swsusp_swapoff:pages:%d\n", si->pages);
> +	if (prev < 0) {
> +		swap_list.head = si->next;
> +	} else {
> +		swap_info[prev].next = si->next;
> +	}
> +	if (type == swap_list.next) {
> +		/* just pick something that's safe... */
> +		swap_list.next = swap_list.head;
> +	}
> +	nr_swap_pages -= si->pages;
> +	total_swap_pages -= si->pages;
> +	bdev = I_BDEV(si->swap_file->f_mapping->host);
> +	swap_list_unlock();
> +
> +	current->flags |= PF_SWAPOFF;
> +	err = try_to_unuse(type);
> +	current->flags &= ~PF_SWAPOFF;
> +
> +	/* wait for any unplug function to finish */
> +	down_write(&swap_unplug_sem);
> +	up_write(&swap_unplug_sem);
> +
> +	if (err) {
> +		pr_debug("swsusp_swapoff:err:%d\n", err);
> +		/* re-insert swap space back into swap_list */
> +		swap_list_lock();
> +		for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
> +			if (si->prio >= swap_info[i].prio)
> +				break;
> +		si->next = i;
> +		if (prev < 0)
> +			swap_list.head = swap_list.next = si - swap_info;
> +		else
> +			swap_info[prev].next = si - swap_info;
> +		nr_swap_pages += si->pages;
> +		total_swap_pages += si->pages;
> +		si->flags |= SWP_WRITEOK;
> +		swap_list_unlock();
> +		goto out;
> +	}
> +
> +	down(&swapon_sem);
> +	swap_list_lock();
> +	drain_mmlist();
> +	swap_device_lock(si);
> +	si->swap_file = NULL;
> +	si->max = 0;
> +	swap_map = si->swap_map;
> +	si->swap_map = NULL;
> +	si->flags = 0;
> +	destroy_swap_extents(si);
> +	swap_device_unlock(si);
> +	swap_list_unlock();
> +	up(&swapon_sem);
> +	vfree(swap_map);
> +
> +	/* set SWSUSP signature, again */
> +	mark_swsusp(resume_dev);
> +
> +	/* release device */
> +	set_blocksize(bdev, si->old_block_size);
> +	bd_release(bdev);
> +	err = 0;
> +
> +out:
> +	return err;
> +}
> +#endif /*CONFIG_PRESERVE_SWSUSP_IMAGE*/
> +
>  asmlinkage long sys_swapoff(const char __user * specialfile)
>  {
>  	struct swap_info_struct * p = NULL;
> ---
> 
> 
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
-- 
Evolution.
Enumerate the requirements.
Consider the interdependencies.
Calculate the probabilities.
Be amazed that people believe it happened. 

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/