path: root/kernel/power/swap.c

/*
 * linux/kernel/power/swap.c
 *
 * This file provides functions for reading the suspend image from
 * and writing it to a swap partition.
 *
 * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 *
 * This file is released under the GPLv2.
 *
 */

#include <linux/module.h>
#include <linux/file.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/genhd.h>
#include <linux/device.h>
#include <linux/buffer_head.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/lzo.h>
#include <linux/vmalloc.h>

#include "power.h"

#define HIBERNATE_SIG	"LINHIB0001"

/*
 *	The swap map is a data structure used for keeping track of each page
 *	written to a swap partition.  It consists of many swap_map_page
 *	structures that contain each an array of MAP_PAGE_ENTRIES swap entries.
 *	These structures are stored on the swap and linked together with the
 *	help of the .next_swap member.
 *
 *	The swap map is created during suspend.  The swap map pages are
 *	allocated and populated one at a time, so we only need one memory
 *	page to set up the entire structure.
 *
 *	During resume we also only need to use one swap_map_page structure
 *	at a time.
 */

#define MAP_PAGE_ENTRIES	(PAGE_SIZE / sizeof(sector_t) - 1)

struct swap_map_page {
	sector_t entries[MAP_PAGE_ENTRIES];
	sector_t next_swap;
};

/**
 *	The swap_map_handle structure is used for handling swap in
 *	a file-alike way
 */

struct swap_map_handle {
	struct swap_map_page *cur;
	sector_t cur_swap;
	sector_t first_sector;
	unsigned int k;
};

struct swsusp_header {
	char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int)];
	sector_t image;
	unsigned int flags;	/* Flags to pass to the "boot" kernel */
	char	orig_sig[10];
	char	sig[10];
} __attribute__((packed));

static struct swsusp_header *swsusp_header;

/**
 *	The following functions are used for tracing the allocated
 *	swap pages, so that they can be freed in case of an error.
 */

struct swsusp_extent {
	struct rb_node node;
	unsigned long start;
	unsigned long end;
};

static struct rb_root swsusp_extents = RB_ROOT;

static int swsusp_extents_insert(unsigned long swap_offset)
{
	struct rb_node **new = &(swsusp_extents.rb_node);
	struct rb_node *parent = NULL;
	struct swsusp_extent *ext;

	/* Figure out where to put the new node */
	while (*new) {
		ext = container_of(*new, struct swsusp_extent, node);
		parent = *new;
		if (swap_offset < ext->start) {
			/* Try to merge */
			if (swap_offset == ext->start - 1) {
				ext->start--;
				return 0;
			}
			new = &((*new)->rb_left);
		} else if (swap_offset > ext->end) {
			/* Try to merge */
			if (swap_offset == ext->end + 1) {
				ext->end++;
				return 0;
			}
			new = &((*new)->rb_right);
		} else {
			/* It already is in the tree */
			return -EINVAL;
		}
	}
	/* Add the new node and rebalance the tree. */
	ext = kzalloc(sizeof(struct swsusp_extent), GFP_KERNEL);
	if (!ext)
		return -ENOMEM;

	ext->start = swap_offset;
	ext->end = swap_offset;
	rb_link_node(&ext->node, parent, new);
	rb_insert_color(&ext->node, &swsusp_extents);
	return 0;
}

/**
 *	alloc_swapdev_block - allocate a swap page and register that it has
 *	been allocated, so that it can be freed in case of an error.
 */

sector_t alloc_swapdev_block(int swap)
{
	unsigned long offset;

	offset = swp_offset(get_swap_page_of_type(swap));
	if (offset) {
		if (swsusp_extents_insert(offset))
			swap_free(swp_entry(swap, offset));
		else
			return swapdev_block(swap, offset);
	}
	return 0;
}

/**
 *	free_all_swap_pages - free swap pages allocated for saving image data.
 *	It also frees the extents used to register which swap entries had been
 *	allocated.
 */

void free_all_swap_pages(int swap)
{
	struct rb_node *node;

	while ((node = swsusp_extents.rb_node)) {
		struct swsusp_extent *ext;
		unsigned long offset;

		ext = container_of(node, struct swsusp_extent, node);
		rb_erase(node, &swsusp_extents);
		for (offset = ext->start; offset <= ext->end; offset++)
			swap_free(swp_entry(swap, offset));

		kfree(ext);
	}
}

int swsusp_swap_in_use(void)
{
	return (swsusp_extents.rb_node != NULL);
}

/*
 * General things
 */

static unsigned short root_swap = 0xffff;
struct block_device *hib_resume_bdev;

/*
 * Saving part
 */

static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
{
	int error;

	hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
	if (!memcmp("SWAP-SPACE",swsusp_header->sig