[PATCH] W1: possible cleanups

[linux-2.6/verdex.git] / 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@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);
}