kernel/power/swap.c - linux/kernel/git/davem/net-next - Git at Google

 /*
  * 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@suse.cz>
  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  *
  * This file is released under the GPLv2.
  *
  */

 #include <linux/module.h>
 #include <linux/smp_lock.h>
 #include <linux/file.h>
 #include <linux/utsname.h>
 #include <linux/version.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 "power.h"

 extern char resume_file[];

 #define SWSUSP_SIG	"S1SUSPEND"

 static struct swsusp_header {
 	char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
 	swp_entry_t image;
 	char	orig_sig[10];
 	char	sig[10];
 } __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;

 /*
  * Saving part...
  */

 static unsigned short root_swap = 0xffff;

 static int mark_swapfiles(swp_entry_t start)
 {
 	int error;

 	rw_swap_page_sync(READ, swp_entry(root_swap, 0),
 			  virt_to_page((unsigned long)&swsusp_header), NULL);
 	if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
 	    !memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
 		memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
 		memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
 		swsusp_header.image = start;
 		error = rw_swap_page_sync(WRITE, swp_entry(root_swap, 0),
 				virt_to_page((unsigned long)&swsusp_header),
 				NULL);
 	} else {
 		pr_debug("swsusp: Partition is not swap space.\n");
 		error = -ENODEV;
 	}
 	return error;
 }

 /**
  *	swsusp_swap_check - check if the resume device is a swap device
  *	and get its index (if so)
  */

 static int swsusp_swap_check(void) /* This is called before saving image */
 {
 	int res = swap_type_of(swsusp_resume_device);

 	if (res >= 0) {
 		root_swap = res;
 		return 0;
 	}
 	return res;
 }

 /**
  *	write_page - Write one page to given swap location.
  *	@buf:		Address we're writing.
  *	@offset:	Offset of the swap page we're writing to.
  *	@bio_chain:	Link the next write BIO here
  */

 static int write_page(void *buf, unsigned long offset, struct bio **bio_chain)
 {
 	swp_entry_t entry;
 	int error = -ENOSPC;

 	if (offset) {
 		struct page *page = virt_to_page(buf);

 		if (bio_chain) {
 			/*
 			 * Whether or not we successfully allocated a copy page,
 			 * we take a ref on the page here.  It gets undone in
 			 * wait_on_bio_chain().
 			 */
 			struct page *page_copy;
 			page_copy = alloc_page(GFP_ATOMIC);
 			if (page_copy == NULL) {
 				WARN_ON_ONCE(1);
 				bio_chain = NULL;	/* Go synchronous */
 				get_page(page);
 			} else {
 				memcpy(page_address(page_copy),
 					page_address(page), PAGE_SIZE);
 				page = page_copy;
 			}
 		}
 		entry = swp_entry(root_swap, offset);
 		error = rw_swap_page_sync(WRITE, entry, page, bio_chain);
 	}
 	return error;
 }

 /*
  *	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_SIZE 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(long) - 1)

 struct swap_map_page {
 	unsigned long		entries[MAP_PAGE_ENTRIES];
 	unsigned long		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;
 	unsigned long cur_swap;
 	struct bitmap_page *bitmap;
 	unsigned int k;
 };

 static void release_swap_writer(struct swap_map_handle *handle)
 {
 	if (handle->cur)
 		free_page((unsigned long)handle->cur);
 	handle->cur = NULL;
 	if (handle->bitmap)
 		free_bitmap(handle->bitmap);
 	handle->bitmap = NULL;
 }

 static void show_speed(struct timeval *start, struct timeval *stop,
 			unsigned nr_pages, char *msg)
 {
 	s64 elapsed_centisecs64;
 	int centisecs;
 	int k;
 	int kps;

 	elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
 	do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
 	centisecs = elapsed_centisecs64;
 	if (centisecs == 0)
 		centisecs = 1;	/* avoid div-by-zero */
 	k = nr_pages * (PAGE_SIZE / 1024);
 	kps = (k * 100) / centisecs;
 	printk("%s %d kbytes in %d.%02d seconds (%d.%02d MB/s)\n", msg, k,
 			centisecs / 100, centisecs % 100,
 			kps / 1000, (kps % 1000) / 10);
 }

 static int get_swap_writer(struct swap_map_handle *handle)
 {
 	handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
 	if (!handle->cur)
 		return -ENOMEM;
 	handle->bitmap = alloc_bitmap(count_swap_pages(root_swap, 0));
 	if (!handle->bitmap) {
 		release_swap_writer(handle);
 		return -ENOMEM;
 	}
 	handle->cur_swap = alloc_swap_page(root_swap, handle->bitmap);
 	if (!handle->cur_swap) {
 		release_swap_writer(handle);
 		return -ENOSPC;
 	}
 	handle->k = 0;
 	return 0;
 }

 static int wait_on_bio_chain(struct bio **bio_chain)
 {
 	struct bio *bio;
 	struct bio *next_bio;
 	int ret = 0;

 	if (bio_chain == NULL)
 		return 0;

 	bio = *bio_chain;
 	if (bio == NULL)
 		return 0;
 	while (bio) {
 		struct page *page;

 		next_bio = bio->bi_private;
 		page = bio->bi_io_vec[0].bv_page;
 		wait_on_page_locked(page);
 		if (!PageUptodate(page) || PageError(page))
 			ret = -EIO;
 		put_page(page);
 		bio_put(bio);
 		bio = next_bio;
 	}
 	*bio_chain = NULL;
 	return ret;
 }

 static int swap_write_page(struct swap_map_handle *handle, void *buf,
 				struct bio **bio_chain)
 {
 	int error = 0;
 	unsigned long offset;

 	if (!handle->cur)
 		return -EINVAL;
 	offset = alloc_swap_page(root_swap, handle->bitmap);
 	error = write_page(buf, offset, bio_chain);
 	if (error)
 		return error;
 	handle->cur->entries[handle->k++] = offset;
 	if (handle->k >= MAP_PAGE_ENTRIES) {
 		error = wait_on_bio_chain(bio_chain);
 		if (error)
 			goto out;
 		offset = alloc_swap_page(root_swap, handle->bitmap);
 		if (!offset)
 			return -ENOSPC;
 		handle->cur->next_swap = offset;
 		error = write_page(handle->cur, handle->cur_swap, NULL);
 		if (error)
 			goto out;
 		memset(handle->cur, 0, PAGE_SIZE);
 		handle->cur_swap = offset;
 		handle->k = 0;
 	}
 out:
 	return error;
 }

 static int flush_swap_writer(struct swap_map_handle *handle)
 {
 	if (handle->cur && handle->cur_swap)
 		return write_page(handle->cur, handle->cur_swap, NULL);
 	else
 		return -EINVAL;
 }

 /**
  *	save_image - save the suspend image data
  */

 static int save_image(struct swap_map_handle *handle,
                       struct snapshot_handle *snapshot,
                       unsigned int nr_to_write)
 {
 	unsigned int m;
 	int ret;
 	int error = 0;
 	int nr_pages;
 	int err2;
 	struct bio *bio;
 	struct timeval start;
 	struct timeval stop;

 	printk("Saving image data pages (%u pages) ...     ", nr_to_write);
 	m = nr_to_write / 100;
 	if (!m)
 		m = 1;
 	nr_pages = 0;
 	bio = NULL;
 	do_gettimeofday(&start);
 	do {
 		ret = snapshot_read_next(snapshot, PAGE_SIZE);
 		if (ret > 0) {
 			error = swap_write_page(handle, data_of(*snapshot),
 						&bio);
 			if (error)
 				break;
 			if (!(nr_pages % m))
 				printk("\b\b\b\b%3d%%", nr_pages / m);
 			nr_pages++;
 		}
 	} while (ret > 0);
 	err2 = wait_on_bio_chain(&bio);
 	do_gettimeofday(&stop);
 	if (!error)
 		error = err2;
 	if (!error)
 		printk("\b\b\b\bdone\n");
 	show_speed(&start, &stop, nr_to_write, "Wrote");
 	return error;
 }

 /**
  *	enough_swap - Make sure we have enough swap to save the image.
  *
  *	Returns TRUE or FALSE after checking the total amount of swap
  *	space avaiable from the resume partition.
  */

 static int enough_swap(unsigned int nr_pages)
 {
 	unsigned int free_swap = count_swap_pages(root_swap, 1);

 	pr_debug("swsusp: free swap pages: %u\n", free_swap);
 	return free_swap > nr_pages + PAGES_FOR_IO;
 }

 /**
  *	swsusp_write - Write entire image and metadata.
  *
  *	It is important _NOT_ to umount filesystems at this point. We want
  *	them synced (in case something goes wrong) but we DO not want to mark
  *	filesystem clean: it is not. (And it does not matter, if we resume
  *	correctly, we'll mark system clean, anyway.)
  */

 int swsusp_write(void)
 {
 	struct swap_map_handle handle;
 	struct snapshot_handle snapshot;
 	struct swsusp_info *header;
 	int error;

 	if ((error = swsusp_swap_check())) {
 		printk(KERN_ERR "swsusp: Cannot find swap device, try "
 				"swapon -a.\n");
 		return error;
 	}
 	memset(&snapshot, 0, sizeof(struct snapshot_handle));
 	error = snapshot_read_next(&snapshot, PAGE_SIZE);
 	if (error < PAGE_SIZE)
 		return error < 0 ? error : -EFAULT;
 	header = (struct swsusp_info *)data_of(snapshot);
 	if (!enough_swap(header->pages)) {
 		printk(KERN_ERR "swsusp: Not enough free swap\n");
 		return -ENOSPC;
 	}
 	error = get_swap_writer(&handle);
 	if (!error) {
 		unsigned long start = handle.cur_swap;
 		error = swap_write_page(&handle, header, NULL);
 		if (!error)
 			error = save_image(&handle, &snapshot,
 					header->pages - 1);
 		if (!error) {
 			flush_swap_writer(&handle);
 			printk("S");
 			error = mark_swapfiles(swp_entry(root_swap, start));
 			printk("|\n");
 		}
 	}
 	if (error)
 		free_all_swap_pages(root_swap, handle.bitmap);
 	release_swap_writer(&handle);
 	return error;
 }

 static struct block_device *resume_bdev;

 /**
  *	submit - submit BIO request.
  *	@rw:	READ or WRITE.
  *	@off	physical offset of page.
  *	@page:	page we're reading or writing.
  *	@bio_chain: list of pending biod (for async reading)
  *
  *	Straight from the textbook - allocate and initialize the bio.
  *	If we're reading, make sure the page is marked as dirty.
  *	Then submit it and, if @bio_chain == NULL, wait.
  */
 static int submit(int rw, pgoff_t page_off, struct page *page,
 			struct bio **bio_chain)
 {
 	struct bio *bio;

 	bio = bio_alloc(GFP_ATOMIC, 1);
 	if (!bio)
 		return -ENOMEM;
 	bio->bi_sector = page_off * (PAGE_SIZE >> 9);
 	bio->bi_bdev = resume_bdev;
 	bio->bi_end_io = end_swap_bio_read;

 	if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
 		printk("swsusp: ERROR: adding page to bio at %ld\n", page_off);
 		bio_put(bio);
 		return -EFAULT;
 	}

 	lock_page(page);
 	bio_get(bio);

 	if (bio_chain == NULL) {
 		submit_bio(rw | (1 << BIO_RW_SYNC), bio);
 		wait_on_page_locked(page);
 		if (rw == READ)
 			bio_set_pages_dirty(bio);
 		bio_put(bio);
 	} else {
 		get_page(page);
 		bio->bi_private = *bio_chain;
 		*bio_chain = bio;
 		submit_bio(rw | (1 << BIO_RW_SYNC), bio);
 	}
 	return 0;
 }

 static int bio_read_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
 {
 	return submit(READ, page_off, virt_to_page(addr), bio_chain);
 }

 static int bio_write_page(pgoff_t page_off, void *addr)
 {
 	return submit(WRITE, page_off, virt_to_page(addr), NULL);
 }

 /**
  *	The following functions allow us to read data using a swap map
  *	in a file-alike way
  */

 static void release_swap_reader(struct swap_map_handle *handle)
 {
 	if (handle->cur)
 		free_page((unsigned long)handle->cur);
 	handle->cur = NULL;
 }

 static int get_swap_reader(struct swap_map_handle *handle,
                                       swp_entry_t start)
 {
 	int error;

 	if (!swp_offset(start))
 		return -EINVAL;
 	handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_ATOMIC);
 	if (!handle->cur)
 		return -ENOMEM;
 	error = bio_read_page(swp_offset(start), handle->cur, NULL);
 	if (error) {
 		release_swap_reader(handle);
 		return error;
 	}
 	handle->k = 0;
 	return 0;
 }

 static int swap_read_page(struct swap_map_handle *handle, void *buf,
 				struct bio **bio_chain)
 {
 	unsigned long offset;
 	int error;

 	if (!handle->cur)
 		return -EINVAL;
 	offset = handle->cur->entries[handle->k];
 	if (!offset)
 		return -EFAULT;
 	error = bio_read_page(offset, buf, bio_chain);
 	if (error)
 		return error;
 	if (++handle->k >= MAP_PAGE_ENTRIES) {
 		error = wait_on_bio_chain(bio_chain);
 		handle->k = 0;
 		offset = handle->cur->next_swap;
 		if (!offset)
 			release_swap_reader(handle);
 		else if (!error)
 			error = bio_read_page(offset, handle->cur, NULL);
 	}
 	return error;
 }

 /**
  *	load_image - load the image using the swap map handle
  *	@handle and the snapshot handle @snapshot
  *	(assume there are @nr_pages pages to load)
  */

 static int load_image(struct swap_map_handle *handle,
                       struct snapshot_handle *snapshot,
                       unsigned int nr_to_read)
 {
 	unsigned int m;
 	int error = 0;
 	struct timeval start;
 	struct timeval stop;
 	struct bio *bio;
 	int err2;
 	unsigned nr_pages;

 	printk("Loading image data pages (%u pages) ...     ", nr_to_read);
 	m = nr_to_read / 100;
 	if (!m)
 		m = 1;
 	nr_pages = 0;
 	bio = NULL;
 	do_gettimeofday(&start);
 	for ( ; ; ) {
 		error = snapshot_write_next(snapshot, PAGE_SIZE);
 		if (error <= 0)
 			break;
 		error = swap_read_page(handle, data_of(*snapshot), &bio);
 		if (error)
 			break;
 		if (snapshot->sync_read)
 			error = wait_on_bio_chain(&bio);
 		if (error)
 			break;
 		if (!(nr_pages % m))
 			printk("\b\b\b\b%3d%%", nr_pages / m);
 		nr_pages++;
 	}
 	err2 = wait_on_bio_chain(&bio);
 	do_gettimeofday(&stop);
 	if (!error)
 		error = err2;
 	if (!error) {
 		printk("\b\b\b\bdone\n");
 		snapshot_free_unused_memory(snapshot);
 		if (!snapshot_image_loaded(snapshot))
 			error = -ENODATA;
 	}
 	show_speed(&start, &stop, nr_to_read, "Read");
 	return error;
 }

 int swsusp_read(void)
 {
 	int error;
 	struct swap_map_handle handle;
 	struct snapshot_handle snapshot;
 	struct swsusp_info *header;

 	if (IS_ERR(resume_bdev)) {
 		pr_debug("swsusp: block device not initialised\n");
 		return PTR_ERR(resume_bdev);
 	}

 	memset(&snapshot, 0, sizeof(struct snapshot_handle));
 	error = snapshot_write_next(&snapshot, PAGE_SIZE);
 	if (error < PAGE_SIZE)
 		return error < 0 ? error : -EFAULT;
 	header = (struct swsusp_info *)data_of(snapshot);
 	error = get_swap_reader(&handle, swsusp_header.image);
 	if (!error)
 		error = swap_read_page(&handle, header, NULL);
 	if (!error)
 		error = load_image(&handle, &snapshot, header->pages - 1);
 	release_swap_reader(&handle);

 	blkdev_put(resume_bdev);

 	if (!error)
 		pr_debug("swsusp: Reading resume file was successful\n");
 	else
 		pr_debug("swsusp: Error %d resuming\n", error);
 	return error;
 }

 /**
  *      swsusp_check - Check for swsusp signature in the resume device
  */

 int swsusp_check(void)
 {
 	int error;

 	resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
 	if (!IS_ERR(resume_bdev)) {
 		set_blocksize(resume_bdev, PAGE_SIZE);
 		memset(&swsusp_header, 0, sizeof(swsusp_header));
 		if ((error = bio_read_page(0, &swsusp_header, NULL)))
 			return error;
 		if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
 			memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
 			/* Reset swap signature now */
 			error = bio_write_page(0, &swsusp_header);
 		} else {
 			return -EINVAL;
 		}
 		if (error)
 			blkdev_put(resume_bdev);
 		else
 			pr_debug("swsusp: Signature found, resuming\n");
 	} else {
 		error = PTR_ERR(resume_bdev);
 	}

 	if (error)
 		pr_debug("swsusp: Error %d check for resume file\n", error);

 	return error;
 }

 /**
  *	swsusp_close - close swap device.
  */

 void swsusp_close(void)
 {
 	if (IS_ERR(resume_bdev)) {
 		pr_debug("swsusp: block device not initialised\n");
 		return;
 	}

 	blkdev_put(resume_bdev);
 }
	/*
	* 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@suse.cz>
	* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
	*
	* This file is released under the GPLv2.
	*
	*/

	#include <linux/module.h>
	#include <linux/smp_lock.h>
	#include <linux/file.h>
	#include <linux/utsname.h>
	#include <linux/version.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 "power.h"

	extern char resume_file[];

	#define SWSUSP_SIG "S1SUSPEND"

	static struct swsusp_header {
	char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
	swp_entry_t image;
	char orig_sig[10];
	char sig[10];
	} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;

	/*
	* Saving part...
	*/

	static unsigned short root_swap = 0xffff;

	static int mark_swapfiles(swp_entry_t start)
	{
	int error;

	rw_swap_page_sync(READ, swp_entry(root_swap, 0),
	virt_to_page((unsigned long)&swsusp_header), NULL);
	if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) \|\|
	!memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
	memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
	memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
	swsusp_header.image = start;
	error = rw_swap_page_sync(WRITE, swp_entry(root_swap, 0),
	virt_to_page((unsigned long)&swsusp_header),
	NULL);
	} else {
	pr_debug("swsusp: Partition is not swap space.\n");
	error = -ENODEV;
	}
	return error;
	}

	/**
	* swsusp_swap_check - check if the resume device is a swap device
	* and get its index (if so)
	*/

	static int swsusp_swap_check(void) /* This is called before saving image */
	{
	int res = swap_type_of(swsusp_resume_device);

	if (res >= 0) {
	root_swap = res;
	return 0;
	}
	return res;
	}

	/**
	* write_page - Write one page to given swap location.
	* @buf: Address we're writing.
	* @offset: Offset of the swap page we're writing to.
	* @bio_chain: Link the next write BIO here
	*/

	static int write_page(void buf, unsigned long offset, struct bio *bio_chain)
	{
	swp_entry_t entry;
	int error = -ENOSPC;

	if (offset) {
	struct page *page = virt_to_page(buf);

	if (bio_chain) {
	/*
	* Whether or not we successfully allocated a copy page,
	* we take a ref on the page here. It gets undone in
	* wait_on_bio_chain().
	*/
	struct page *page_copy;
	page_copy = alloc_page(GFP_ATOMIC);
	if (page_copy == NULL) {
	WARN_ON_ONCE(1);
	bio_chain = NULL; /* Go synchronous */
	get_page(page);
	} else {
	memcpy(page_address(page_copy),
	page_address(page), PAGE_SIZE);
	page = page_copy;
	}
	}
	entry = swp_entry(root_swap, offset);
	error = rw_swap_page_sync(WRITE, entry, page, bio_chain);
	}
	return error;
	}

	/*
	* 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_SIZE 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(long) - 1)

	struct swap_map_page {
	unsigned long entries[MAP_PAGE_ENTRIES];
	unsigned long 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;
	unsigned long cur_swap;
	struct bitmap_page *bitmap;
	unsigned int k;
	};

	static void release_swap_writer(struct swap_map_handle *handle)
	{
	if (handle->cur)
	free_page((unsigned long)handle->cur);
	handle->cur = NULL;
	if (handle->bitmap)
	free_bitmap(handle->bitmap);
	handle->bitmap = NULL;
	}

	static void show_speed(struct timeval start, struct timeval stop,
	unsigned nr_pages, char *msg)
	{
	s64 elapsed_centisecs64;
	int centisecs;
	int k;
	int kps;

	elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
	do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
	centisecs = elapsed_centisecs64;
	if (centisecs == 0)
	centisecs = 1; /* avoid div-by-zero */
	k = nr_pages * (PAGE_SIZE / 1024);
	kps = (k * 100) / centisecs;
	printk("%s %d kbytes in %d.%02d seconds (%d.%02d MB/s)\n", msg, k,
	centisecs / 100, centisecs % 100,
	kps / 1000, (kps % 1000) / 10);
	}

	static int get_swap_writer(struct swap_map_handle *handle)
	{
	handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
	if (!handle->cur)
	return -ENOMEM;
	handle->bitmap = alloc_bitmap(count_swap_pages(root_swap, 0));
	if (!handle->bitmap) {
	release_swap_writer(handle);
	return -ENOMEM;
	}
	handle->cur_swap = alloc_swap_page(root_swap, handle->bitmap);
	if (!handle->cur_swap) {
	release_swap_writer(handle);
	return -ENOSPC;
	}
	handle->k = 0;
	return 0;
	}

	static int wait_on_bio_chain(struct bio **bio_chain)
	{
	struct bio *bio;
	struct bio *next_bio;
	int ret = 0;

	if (bio_chain == NULL)
	return 0;

	bio = *bio_chain;
	if (bio == NULL)
	return 0;
	while (bio) {
	struct page *page;

	next_bio = bio->bi_private;
	page = bio->bi_io_vec[0].bv_page;
	wait_on_page_locked(page);
	if (!PageUptodate(page) \|\| PageError(page))
	ret = -EIO;
	put_page(page);
	bio_put(bio);
	bio = next_bio;
	}
	*bio_chain = NULL;
	return ret;
	}

	static int swap_write_page(struct swap_map_handle handle, void buf,
	struct bio **bio_chain)
	{
	int error = 0;
	unsigned long offset;

	if (!handle->cur)
	return -EINVAL;
	offset = alloc_swap_page(root_swap, handle->bitmap);
	error = write_page(buf, offset, bio_chain);
	if (error)
	return error;
	handle->cur->entries[handle->k++] = offset;
	if (handle->k >= MAP_PAGE_ENTRIES) {
	error = wait_on_bio_chain(bio_chain);
	if (error)
	goto out;
	offset = alloc_swap_page(root_swap, handle->bitmap);
	if (!offset)
	return -ENOSPC;
	handle->cur->next_swap = offset;
	error = write_page(handle->cur, handle->cur_swap, NULL);
	if (error)
	goto out;
	memset(handle->cur, 0, PAGE_SIZE);
	handle->cur_swap = offset;
	handle->k = 0;
	}
	out:
	return error;
	}

	static int flush_swap_writer(struct swap_map_handle *handle)
	{
	if (handle->cur && handle->cur_swap)
	return write_page(handle->cur, handle->cur_swap, NULL);
	else
	return -EINVAL;
	}

	/**
	* save_image - save the suspend image data
	*/

	static int save_image(struct swap_map_handle *handle,
	struct snapshot_handle *snapshot,
	unsigned int nr_to_write)
	{
	unsigned int m;
	int ret;
	int error = 0;
	int nr_pages;
	int err2;
	struct bio *bio;
	struct timeval start;
	struct timeval stop;

	printk("Saving image data pages (%u pages) ... ", nr_to_write);
	m = nr_to_write / 100;
	if (!m)
	m = 1;
	nr_pages = 0;
	bio = NULL;
	do_gettimeofday(&start);
	do {
	ret = snapshot_read_next(snapshot, PAGE_SIZE);
	if (ret > 0) {
	error = swap_write_page(handle, data_of(*snapshot),
	&bio);
	if (error)
	break;
	if (!(nr_pages % m))
	printk("\b\b\b\b%3d%%", nr_pages / m);
	nr_pages++;
	}
	} while (ret > 0);
	err2 = wait_on_bio_chain(&bio);
	do_gettimeofday(&stop);
	if (!error)
	error = err2;
	if (!error)
	printk("\b\b\b\bdone\n");
	show_speed(&start, &stop, nr_to_write, "Wrote");
	return error;
	}

	/**
	* enough_swap - Make sure we have enough swap to save the image.
	*
	* Returns TRUE or FALSE after checking the total amount of swap
	* space avaiable from the resume partition.
	*/

	static int enough_swap(unsigned int nr_pages)
	{
	unsigned int free_swap = count_swap_pages(root_swap, 1);

	pr_debug("swsusp: free swap pages: %u\n", free_swap);
	return free_swap > nr_pages + PAGES_FOR_IO;
	}

	/**
	* swsusp_write - Write entire image and metadata.
	*
	* It is important _NOT_ to umount filesystems at this point. We want
	* them synced (in case something goes wrong) but we DO not want to mark
	* filesystem clean: it is not. (And it does not matter, if we resume
	* correctly, we'll mark system clean, anyway.)
	*/

	int swsusp_write(void)
	{
	struct swap_map_handle handle;
	struct snapshot_handle snapshot;
	struct swsusp_info *header;
	int error;

	if ((error = swsusp_swap_check())) {
	printk(KERN_ERR "swsusp: Cannot find swap device, try "
	"swapon -a.\n");
	return error;
	}
	memset(&snapshot, 0, sizeof(struct snapshot_handle));
	error = snapshot_read_next(&snapshot, PAGE_SIZE);
	if (error < PAGE_SIZE)
	return error < 0 ? error : -EFAULT;
	header = (struct swsusp_info *)data_of(snapshot);
	if (!enough_swap(header->pages)) {
	printk(KERN_ERR "swsusp: Not enough free swap\n");
	return -ENOSPC;
	}
	error = get_swap_writer(&handle);
	if (!error) {
	unsigned long start = handle.cur_swap;
	error = swap_write_page(&handle, header, NULL);
	if (!error)
	error = save_image(&handle, &snapshot,
	header->pages - 1);
	if (!error) {
	flush_swap_writer(&handle);
	printk("S");
	error = mark_swapfiles(swp_entry(root_swap, start));
	printk("\|\n");
	}
	}
	if (error)
	free_all_swap_pages(root_swap, handle.bitmap);
	release_swap_writer(&handle);
	return error;
	}

	static struct block_device *resume_bdev;

	/**
	* submit - submit BIO request.
	* @rw: READ or WRITE.
	* @off physical offset of page.
	* @page: page we're reading or writing.
	* @bio_chain: list of pending biod (for async reading)
	*
	* Straight from the textbook - allocate and initialize the bio.
	* If we're reading, make sure the page is marked as dirty.
	* Then submit it and, if @bio_chain == NULL, wait.
	*/
	static int submit(int rw, pgoff_t page_off, struct page *page,
	struct bio **bio_chain)
	{
	struct bio *bio;

	bio = bio_alloc(GFP_ATOMIC, 1);
	if (!bio)
	return -ENOMEM;
	bio->bi_sector = page_off * (PAGE_SIZE >> 9);
	bio->bi_bdev = resume_bdev;
	bio->bi_end_io = end_swap_bio_read;

	if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
	printk("swsusp: ERROR: adding page to bio at %ld\n", page_off);
	bio_put(bio);
	return -EFAULT;
	}

	lock_page(page);
	bio_get(bio);

	if (bio_chain == NULL) {
	submit_bio(rw \| (1 << BIO_RW_SYNC), bio);
	wait_on_page_locked(page);
	if (rw == READ)
	bio_set_pages_dirty(bio);
	bio_put(bio);
	} else {
	get_page(page);
	bio->bi_private = *bio_chain;
	*bio_chain = bio;
	submit_bio(rw \| (1 << BIO_RW_SYNC), bio);
	}
	return 0;
	}

	static int bio_read_page(pgoff_t page_off, void addr, struct bio *bio_chain)
	{
	return submit(READ, page_off, virt_to_page(addr), bio_chain);
	}

	static int bio_write_page(pgoff_t page_off, void *addr)
	{
	return submit(WRITE, page_off, virt_to_page(addr), NULL);
	}

	/**
	* The following functions allow us to read data using a swap map
	* in a file-alike way
	*/

	static void release_swap_reader(struct swap_map_handle *handle)
	{
	if (handle->cur)
	free_page((unsigned long)handle->cur);
	handle->cur = NULL;
	}

	static int get_swap_reader(struct swap_map_handle *handle,
	swp_entry_t start)
	{
	int error;

	if (!swp_offset(start))
	return -EINVAL;
	handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_ATOMIC);
	if (!handle->cur)
	return -ENOMEM;
	error = bio_read_page(swp_offset(start), handle->cur, NULL);
	if (error) {
	release_swap_reader(handle);
	return error;
	}
	handle->k = 0;
	return 0;
	}

	static int swap_read_page(struct swap_map_handle handle, void buf,
	struct bio **bio_chain)
	{
	unsigned long offset;
	int error;

	if (!handle->cur)
	return -EINVAL;
	offset = handle->cur->entries[handle->k];
	if (!offset)
	return -EFAULT;
	error = bio_read_page(offset, buf, bio_chain);
	if (error)
	return error;
	if (++handle->k >= MAP_PAGE_ENTRIES) {
	error = wait_on_bio_chain(bio_chain);
	handle->k = 0;
	offset = handle->cur->next_swap;
	if (!offset)
	release_swap_reader(handle);
	else if (!error)
	error = bio_read_page(offset, handle->cur, NULL);
	}
	return error;
	}

	/**
	* load_image - load the image using the swap map handle
	* @handle and the snapshot handle @snapshot
	* (assume there are @nr_pages pages to load)
	*/

	static int load_image(struct swap_map_handle *handle,
	struct snapshot_handle *snapshot,
	unsigned int nr_to_read)
	{
	unsigned int m;
	int error = 0;
	struct timeval start;
	struct timeval stop;
	struct bio *bio;
	int err2;
	unsigned nr_pages;

	printk("Loading image data pages (%u pages) ... ", nr_to_read);
	m = nr_to_read / 100;
	if (!m)
	m = 1;
	nr_pages = 0;
	bio = NULL;
	do_gettimeofday(&start);
	for ( ; ; ) {
	error = snapshot_write_next(snapshot, PAGE_SIZE);
	if (error <= 0)
	break;
	error = swap_read_page(handle, data_of(*snapshot), &bio);
	if (error)
	break;
	if (snapshot->sync_read)
	error = wait_on_bio_chain(&bio);
	if (error)
	break;
	if (!(nr_pages % m))
	printk("\b\b\b\b%3d%%", nr_pages / m);
	nr_pages++;
	}
	err2 = wait_on_bio_chain(&bio);
	do_gettimeofday(&stop);
	if (!error)
	error = err2;
	if (!error) {
	printk("\b\b\b\bdone\n");
	snapshot_free_unused_memory(snapshot);
	if (!snapshot_image_loaded(snapshot))
	error = -ENODATA;
	}
	show_speed(&start, &stop, nr_to_read, "Read");
	return error;
	}

	int swsusp_read(void)
	{
	int error;
	struct swap_map_handle handle;
	struct snapshot_handle snapshot;
	struct swsusp_info *header;

	if (IS_ERR(resume_bdev)) {
	pr_debug("swsusp: block device not initialised\n");
	return PTR_ERR(resume_bdev);
	}

	memset(&snapshot, 0, sizeof(struct snapshot_handle));
	error = snapshot_write_next(&snapshot, PAGE_SIZE);
	if (error < PAGE_SIZE)
	return error < 0 ? error : -EFAULT;
	header = (struct swsusp_info *)data_of(snapshot);
	error = get_swap_reader(&handle, swsusp_header.image);
	if (!error)
	error = swap_read_page(&handle, header, NULL);
	if (!error)
	error = load_image(&handle, &snapshot, header->pages - 1);
	release_swap_reader(&handle);

	blkdev_put(resume_bdev);

	if (!error)
	pr_debug("swsusp: Reading resume file was successful\n");
	else
	pr_debug("swsusp: Error %d resuming\n", error);
	return error;
	}

	/**
	* swsusp_check - Check for swsusp signature in the resume device
	*/

	int swsusp_check(void)
	{
	int error;

	resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
	if (!IS_ERR(resume_bdev)) {
	set_blocksize(resume_bdev, PAGE_SIZE);
	memset(&swsusp_header, 0, sizeof(swsusp_header));
	if ((error = bio_read_page(0, &swsusp_header, NULL)))
	return error;
	if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
	memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
	/* Reset swap signature now */
	error = bio_write_page(0, &swsusp_header);
	} else {
	return -EINVAL;
	}
	if (error)
	blkdev_put(resume_bdev);
	else
	pr_debug("swsusp: Signature found, resuming\n");
	} else {
	error = PTR_ERR(resume_bdev);
	}

	if (error)
	pr_debug("swsusp: Error %d check for resume file\n", error);

	return error;
	}

	/**
	* swsusp_close - close swap device.
	*/

	void swsusp_close(void)
	{
	if (IS_ERR(resume_bdev)) {
	pr_debug("swsusp: block device not initialised\n");
	return;
	}

	blkdev_put(resume_bdev);
	}