[PATCH] swsusp: separate swap-writing/reading code

obj-y				:= main.o process.o console.o

obj-$(CONFIG_PM_LEGACY)		+= pm.o

obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o disk.o snapshot.o

obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o disk.o snapshot.o swap.o

obj-$(CONFIG_SUSPEND_SMP)	+= smp.o

/* Preferred image size in bytes (default 500 MB) */

extern unsigned long image_size;

extern int in_suspend;

extern dev_t swsusp_resume_device;

extern asmlinkage int swsusp_arch_suspend(void);

extern asmlinkage int swsusp_arch_resume(void);

extern int snapshot_read_next(struct snapshot_handle *handle, size_t count);

extern int snapshot_write_next(struct snapshot_handle *handle, size_t count);

int snapshot_image_loaded(struct snapshot_handle *handle);

/**

 *	The bitmap is used for tracing allocated swap pages

 *

 *	The entire bitmap consists of a number of bitmap_page

 *	structures linked with the help of the .next member.

 *	Thus each page can be allocated individually, so we only

 *	need to make 0-order memory allocations to create

 *	the bitmap.

 */

#define BITMAP_PAGE_SIZE	(PAGE_SIZE - sizeof(void *))

#define BITMAP_PAGE_CHUNKS	(BITMAP_PAGE_SIZE / sizeof(long))

#define BITS_PER_CHUNK		(sizeof(long) * 8)

#define BITMAP_PAGE_BITS	(BITMAP_PAGE_CHUNKS * BITS_PER_CHUNK)

struct bitmap_page {

	unsigned long		chunks[BITMAP_PAGE_CHUNKS];

	struct bitmap_page	*next;

};

extern void free_bitmap(struct bitmap_page *bitmap);

extern struct bitmap_page *alloc_bitmap(unsigned int nr_bits);

extern unsigned long alloc_swap_page(int swap, struct bitmap_page *bitmap);

extern void free_all_swap_pages(int swap, struct bitmap_page *bitmap);

extern int swsusp_shrink_memory(void);

extern int swsusp_suspend(void);

extern int swsusp_resume(void);

/*

 * 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/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));

	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));

	} 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.

 */

static int write_page(void *buf, unsigned long offset)

{

	swp_entry_t entry;

	int error = -ENOSPC;

	if (offset) {

		entry = swp_entry(root_swap, offset);

		error = rw_swap_page_sync(WRITE, entry, virt_to_page(buf));

	}

	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 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 swap_write_page(struct swap_map_handle *handle, void *buf)

{

	int error;

	unsigned long offset;

	if (!handle->cur)

		return -EINVAL;

	offset = alloc_swap_page(root_swap, handle->bitmap);

	error = write_page(buf, offset);

	if (error)

		return error;

	handle->cur->entries[handle->k++] = offset;

	if (handle->k >= MAP_PAGE_ENTRIES) {

		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);

		if (error)

			return error;

		memset(handle->cur, 0, PAGE_SIZE);

		handle->cur_swap = offset;

		handle->k = 0;

	}

	return 0;

}

static int flush_swap_writer(struct swap_map_handle *handle)

{

	if (handle->cur && handle->cur_swap)

		return write_page(handle->cur, handle->cur_swap);

	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_pages)

{

	unsigned int m;

	int ret;

	int error = 0;

	printk("Saving image data pages (%u pages) ...     ", nr_pages);

	m = nr_pages / 100;

	if (!m)

		m = 1;

	nr_pages = 0;

	do {

		ret = snapshot_read_next(snapshot, PAGE_SIZE);

		if (ret > 0) {

			error = swap_write_page(handle, data_of(*snapshot));

			if (error)

				break;

			if (!(nr_pages % m))

				printk("\b\b\b\b%3d%%", nr_pages / m);

			nr_pages++;

		}

	} while (ret > 0);

	if (!error)

		printk("\b\b\b\bdone\n");

	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 +

		(nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);

}

/**

 *	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;

	unsigned long start;

	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) {

		start = handle.cur_swap;

		error = swap_write_page(&handle, header);

	}

	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;

}

/*

 *	Using bio to read from swap.

 *	This code requires a bit more work than just using buffer heads

 *	but, it is the recommended way for 2.5/2.6.

 *	The following are to signal the beginning and end of I/O. Bios

 *	finish asynchronously, while we want them to happen synchronously.

 *	A simple atomic_t, and a wait loop take care of this problem.

 */

static atomic_t io_done = ATOMIC_INIT(0);

static int end_io(struct bio *bio, unsigned int num, int err)

{

	if (!test_bit(BIO_UPTODATE, &bio->bi_flags))

		panic("I/O error reading memory image");

	atomic_set(&io_done, 0);

	return 0;

}

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.

 *

 *	Straight from the textbook - allocate and initialize the bio.

 *	If we're writing, make sure the page is marked as dirty.

 *	Then submit it and wait.

 */

static int submit(int rw, pgoff_t page_off, void *page)

{

	int error = 0;

	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_io;

	if (bio_add_page(bio, virt_to_page(page), PAGE_SIZE, 0) < PAGE_SIZE) {

		printk("swsusp: ERROR: adding page to bio at %ld\n",page_off);

		error = -EFAULT;

		goto Done;

	}

	atomic_set(&io_done, 1);

	submit_bio(rw | (1 << BIO_RW_SYNC), bio);

	while (atomic_read(&io_done))

		yield();

	if (rw == READ)

		bio_set_pages_dirty(bio);

 Done:

	bio_put(bio);

	return error;

}

static int bio_read_page(pgoff_t page_off, void *page)

{

	return submit(READ, page_off, page);

}

static int bio_write_page(pgoff_t page_off, void *page)

{

	return submit(WRITE, page_off, page);

}

/**

 *	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);

	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)

{

	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);

	if (error)

		return error;

	if (++handle->k >= MAP_PAGE_ENTRIES) {

		handle->k = 0;

		offset = handle->cur->next_swap;

		if (!offset)

			release_swap_reader(handle);

		else

			error = bio_read_page(offset, handle->cur);

	}

	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_pages)

{

	unsigned int m;

	int ret;

	int error = 0;

	printk("Loading image data pages (%u pages) ...     ", nr_pages);

	m = nr_pages / 100;

	if (!m)

		m = 1;

	nr_pages = 0;

	do {

		ret = snapshot_write_next(snapshot, PAGE_SIZE);

		if (ret > 0) {

			error = swap_read_page(handle, data_of(*snapshot));

			if (error)

				break;

			if (!(nr_pages % m))

				printk("\b\b\b\b%3d%%", nr_pages / m);

			nr_pages++;

		}

	} while (ret > 0);

	if (!error)

		printk("\b\b\b\bdone\n");

	if (!snapshot_image_loaded(snapshot))

		error = -ENODATA;

	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);

	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)))

			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);

}