swap.c

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/*
 * 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 <[email protected]>
 * Copyright (C) 2006 Rafael J. Wysocki <[email protected]>
 * Copyright (C) 2010-2012 Bojan Smojver <[email protected]>
 *
 * 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/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 <linux/cpumask.h>
#include <linux/atomic.h>
#include <linux/kthread.h>
#include <linux/crc32.h>

#include "power.h"

#define HIBERNATE_SIG   "S1SUSPEND"

/*
 *  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 pick up all swap_map_page structures into a list.
 */

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

/*
 * Number of free pages that are not high.
 */
static inline unsigned long low_free_pages(void)
{
    return nr_free_pages() - nr_free_highpages();
}

/*
 * Number of pages required to be kept free while writing the image. Always
 * half of all available low pages before the writing starts.
 */
static inline unsigned long reqd_free_pages(void)
{
    return low_free_pages() / 2;
}

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

struct swap_map_page_list {
    struct swap_map_page *map;
    struct swap_map_page_list *next;
};

struct swap_map_handle {
    struct swap_map_page *cur;
    struct swap_map_page_list *maps;
    sector_t cur_swap;
    sector_t first_sector;
    unsigned int k;
    unsigned long reqd_free_pages;
    u32 crc32;
};

struct swsusp_header {
    char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -
                  sizeof(u32)];
    u32 crc32;
    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;

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;
}

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;
}

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, 10) ||
        !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
        memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
        memcpy(swsusp_header->sig, HIBERNATE_SIG, 10);
        swsusp_header->image = handle->first_sector;
        swsusp_header->flags = flags;
        if (flags & SF_CRC32_MODE)
            swsusp_header->crc32 = handle->crc32;
        error = hib_bio_write_page(swsusp_resume_block,
                    swsusp_header, NULL);
    } else {
        printk(KERN_ERR "PM: Swap header not found!\n");
        error = -ENODEV;
    }
    return error;
}

static int swsusp_swap_check(void)
{
    int res;

    res = swap_type_of(swsusp_resume_device, swsusp_resume_block,
            &hib_resume_bdev);
    if (res < 0)
        return res;

    root_swap = res;
    res = blkdev_get(hib_resume_bdev, FMODE_WRITE, NULL);
    if (res)
        return res;

    res = set_blocksize(hib_resume_bdev, PAGE_SIZE);
    if (res < 0)
        blkdev_put(hib_resume_bdev, FMODE_WRITE);

    return res;
}

static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
{
    void *src;
    int ret;

    if (!offset)
        return -ENOSPC;

    if (bio_chain) {
        src = (void *)__get_free_page(__GFP_WAIT | __GFP_NOWARN |
                                      __GFP_NORETRY);
        if (src) {
            copy_page(src, buf);
        } else {
            ret = hib_wait_on_bio_chain(bio_chain); /* Free pages */
            if (ret)
                return ret;
            src = (void *)__get_free_page(__GFP_WAIT |
                                          __GFP_NOWARN |
                                          __GFP_NORETRY);
            if (src) {
                copy_page(src, buf);
            } else {
                WARN_ON_ONCE(1);
                bio_chain = NULL;   /* Go synchronous */
                src = buf;
            }
        }
    } else {
        src = buf;
    }
    return hib_bio_write_page(offset, src, bio_chain);
}

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

static int get_swap_writer(struct swap_map_handle *handle)
{
    int ret;

    ret = swsusp_swap_check();
    if (ret) {
        if (ret != -ENOSPC)
            printk(KERN_ERR "PM: Cannot find swap device, try "
                    "swapon -a.\n");
        return ret;
    }
    handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
    if (!handle->cur) {
        ret = -ENOMEM;
        goto err_close;
    }
    handle->cur_swap = alloc_swapdev_block(root_swap);
    if (!handle->cur_swap) {
        ret = -ENOSPC;
        goto err_rel;
    }
    handle->k = 0;
    handle->reqd_free_pages = reqd_free_pages();
    handle->first_sector = handle->cur_swap;
    return 0;
err_rel:
    release_swap_writer(handle);
err_close:
    swsusp_close(FMODE_WRITE);
    return ret;
}

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

    if (!handle->cur)
        return -EINVAL;
    offset = alloc_swapdev_block(root_swap);
    error = write_page(buf, offset, bio_chain);
    if (error)
        return error;
    handle->cur->entries[handle->k++] = offset;
    if (handle->k >= MAP_PAGE_ENTRIES) {
        offset = alloc_swapdev_block(root_swap);
        if (!offset)
            return -ENOSPC;
        handle->cur->next_swap = offset;
        error = write_page(handle->cur, handle->cur_swap, bio_chain);
        if (error)
            goto out;
        clear_page(handle->cur);
        handle->cur_swap = offset;
        handle->k = 0;

        if (bio_chain && low_free_pages() <= handle->reqd_free_pages) {
            error = hib_wait_on_bio_chain(bio_chain);
            if (error)
                goto out;
            /*
             * Recalculate the number of required free pages, to
             * make sure we never take more than half.
             */
            handle->reqd_free_pages = reqd_free_pages();
        }
    }
 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;
}

static int swap_writer_finish(struct swap_map_handle *handle,
        unsigned int flags, int error)
{
    if (!error) {
        flush_swap_writer(handle);
        printk(KERN_INFO "PM: S");
        error = mark_swapfiles(handle, flags);
        printk("|\n");
    }

    if (error)
        free_all_swap_pages(root_swap);
    release_swap_writer(handle);
    swsusp_close(FMODE_WRITE);

    return error;
}

/* We need to remember how much compressed data we need to read. */
#define LZO_HEADER  sizeof(size_t)

/* Number of pages/bytes we'll compress at one time. */
#define LZO_UNC_PAGES   32
#define LZO_UNC_SIZE    (LZO_UNC_PAGES * PAGE_SIZE)

/* Number of pages/bytes we need for compressed data (worst case). */
#define LZO_CMP_PAGES   DIV_ROUND_UP(lzo1x_worst_compress(LZO_UNC_SIZE) + \
                         LZO_HEADER, PAGE_SIZE)
#define LZO_CMP_SIZE    (LZO_CMP_PAGES * PAGE_SIZE)

/* Maximum number of threads for compression/decompression. */
#define LZO_THREADS 3

/* Minimum/maximum number of pages for read buffering. */
#define LZO_MIN_RD_PAGES    1024
#define LZO_MAX_RD_PAGES    8192


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

    printk(KERN_INFO "PM: Saving image data pages (%u pages)...\n",
        nr_to_write);
    m = nr_to_write / 10;
    if (!m)
        m = 1;
    nr_pages = 0;
    bio = NULL;
    do_gettimeofday(&start);
    while (1) {
        ret = snapshot_read_next(snapshot);
        if (ret <= 0)
            break;
        ret = swap_write_page(handle, data_of(*snapshot), &bio);
        if (ret)
            break;
        if (!(nr_pages % m))
            printk(KERN_INFO "PM: Image saving progress: %3d%%\n",
                   nr_pages / m * 10);
        nr_pages++;
    }
    err2 = hib_wait_on_bio_chain(&bio);
    do_gettimeofday(&stop);
    if (!ret)
        ret = err2;
    if (!ret)
        printk(KERN_INFO "PM: Image saving done.\n");
    swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
    return ret;
}

struct crc_data {
    struct task_struct *thr;                  /* thread */
    atomic_t ready;                           /* ready to start flag */
    atomic_t stop;                            /* ready to stop flag */
    unsigned run_threads;                     /* nr current threads */
    wait_queue_head_t go;                     /* start crc update */
    wait_queue_head_t done;                   /* crc update done */
    u32 *crc32;                               /* points to handle's crc32 */
    size_t *unc_len[LZO_THREADS];             /* uncompressed lengths */
    unsigned char *unc[LZO_THREADS];          /* uncompressed data */
};

static int crc32_threadfn(void *data)
{
    struct crc_data *d = data;
    unsigned i;

    while (1) {
        wait_event(d->go, atomic_read(&d->ready) ||
                          kthread_should_stop());
        if (kthread_should_stop()) {
            d->thr = NULL;
            atomic_set(&d->stop, 1);
            wake_up(&d->done);
            break;
        }
        atomic_set(&d->ready, 0);

        for (i = 0; i < d->run_threads; i++)
            *d->crc32 = crc32_le(*d->crc32,
                                 d->unc[i], *d->unc_len[i]);
        atomic_set(&d->stop, 1);
        wake_up(&d->done);
    }
    return 0;
}
struct cmp_data {
    struct task_struct *thr;                  /* thread */
    atomic_t ready;                           /* ready to start flag */
    atomic_t stop;                            /* ready to stop flag */
    int ret;                                  /* return code */
    wait_queue_head_t go;                     /* start compression */
    wait_queue_head_t done;                   /* compression done */
    size_t unc_len;                           /* uncompressed length */
    size_t cmp_len;                           /* compressed length */
    unsigned char unc[LZO_UNC_SIZE];          /* uncompressed buffer */
    unsigned char cmp[LZO_CMP_SIZE];          /* compressed buffer */
    unsigned char wrk[LZO1X_1_MEM_COMPRESS];  /* compression workspace */
};

static int lzo_compress_threadfn(void *data)
{
    struct cmp_data *d = data;

    while (1) {
        wait_event(d->go, atomic_read(&d->ready) ||
                          kthread_should_stop());
        if (kthread_should_stop()) {
            d->thr = NULL;
            d->ret = -1;
            atomic_set(&d->stop, 1);
            wake_up(&d->done);
            break;
        }
        atomic_set(&d->ready, 0);

        d->ret = lzo1x_1_compress(d->unc, d->unc_len,
                                  d->cmp + LZO_HEADER, &d->cmp_len,
                                  d->wrk);
        atomic_set(&d->stop, 1);
        wake_up(&d->done);
    }
    return 0;
}

static int save_image_lzo(struct swap_map_handle *handle,
                          struct snapshot_handle *snapshot,
                          unsigned int nr_to_write)
{
    unsigned int m;
    int ret = 0;
    int nr_pages;
    int err2;
    struct bio *bio;
    struct timeval start;
    struct timeval stop;
    size_t off;
    unsigned thr, run_threads, nr_threads;
    unsigned char *page = NULL;
    struct cmp_data *data = NULL;
    struct crc_data *crc = NULL;

    /*
     * We'll limit the number of threads for compression to limit memory
     * footprint.
     */
    nr_threads = num_online_cpus() - 1;
    nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);

    page = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
    if (!page) {
        printk(KERN_ERR "PM: Failed to allocate LZO page\n");
        ret = -ENOMEM;
        goto out_clean;
    }

    data = vmalloc(sizeof(*data) * nr_threads);
    if (!data) {
        printk(KERN_ERR "PM: Failed to allocate LZO data\n");
        ret = -ENOMEM;
        goto out_clean;
    }
    for (thr = 0; thr < nr_threads; thr++)
        memset(&data[thr], 0, offsetof(struct cmp_data, go));

    crc = kmalloc(sizeof(*crc), GFP_KERNEL);
    if (!crc) {
        printk(KERN_ERR "PM: Failed to allocate crc\n");
        ret = -ENOMEM;
        goto out_clean;
    }
    memset(crc, 0, offsetof(struct crc_data, go));

    /*
     * Start the compression threads.
     */
    for (thr = 0; thr < nr_threads; thr++) {
        init_waitqueue_head(&data[thr].go);
        init_waitqueue_head(&data[thr].done);

        data[thr].thr = kthread_run(lzo_compress_threadfn,
                                    &data[thr],
                                    "image_compress/%u", thr);
        if (IS_ERR(data[thr].thr)) {
            data[thr].thr = NULL;
            printk(KERN_ERR
                   "PM: Cannot start compression threads\n");
            ret = -ENOMEM;
            goto out_clean;
        }
    }

    /*
     * Start the CRC32 thread.
     */
    init_waitqueue_head(&crc->go);
    init_waitqueue_head(&crc->done);

    handle->crc32 = 0;
    crc->crc32 = &handle->crc32;
    for (thr = 0; thr < nr_threads; thr++) {
        crc->unc[thr] = data[thr].unc;
        crc->unc_len[thr] = &data[thr].unc_len;
    }

    crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
    if (IS_ERR(crc->thr)) {
        crc->thr = NULL;
        printk(KERN_ERR "PM: Cannot start CRC32 thread\n");
        ret = -ENOMEM;
        goto out_clean;
    }

    /*
     * Adjust the number of required free pages after all allocations have
     * been done. We don't want to run out of pages when writing.
     */
    handle->reqd_free_pages = reqd_free_pages();

    printk(KERN_INFO
        "PM: Using %u thread(s) for compression.\n"
        "PM: Compressing and saving image data (%u pages)...\n",
        nr_threads, nr_to_write);
    m = nr_to_write / 10;
    if (!m)
        m = 1;
    nr_pages = 0;
    bio = NULL;
    do_gettimeofday(&start);
    for (;;) {
        for (thr = 0; thr < nr_threads; thr++) {
            for (off = 0; off < LZO_UNC_SIZE; off += PAGE_SIZE) {
                ret = snapshot_read_next(snapshot);
                if (ret < 0)
                    goto out_finish;

                if (!ret)
                    break;

                memcpy(data[thr].unc + off,
                       data_of(*snapshot), PAGE_SIZE);

                if (!(nr_pages % m))
                    printk(KERN_INFO
                           "PM: Image saving progress: "
                           "%3d%%\n",
                               nr_pages / m * 10);
                nr_pages++;
            }
            if (!off)
                break;

            data[thr].unc_len = off;

            atomic_set(&data[thr].ready, 1);
            wake_up(&data[thr].go);
        }

        if (!thr)
            break;

        crc->run_threads = thr;
        atomic_set(&crc->ready, 1);
        wake_up(&crc->go);

        for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
            wait_event(data[thr].done,
                       atomic_read(&data[thr].stop));
            atomic_set(&data[thr].stop, 0);

            ret = data[thr].ret;

            if (ret < 0) {
                printk(KERN_ERR "PM: LZO compression failed\n");
                goto out_finish;
            }

            if (unlikely(!data[thr].cmp_len ||
                         data[thr].cmp_len >
                         lzo1x_worst_compress(data[thr].unc_len))) {
                printk(KERN_ERR
                       "PM: Invalid LZO compressed length\n");
                ret = -1;
                goto out_finish;
            }

            *(size_t *)data[thr].cmp = data[thr].cmp_len;

            /*
             * Given we are writing one page at a time to disk, we
             * copy that much from the buffer, although the last
             * bit will likely be smaller than full page. This is
             * OK - we saved the length of the compressed data, so
             * any garbage at the end will be discarded when we
             * read it.
             */
            for (off = 0;
                 off < LZO_HEADER + data[thr].cmp_len;
                 off += PAGE_SIZE) {
                memcpy(page, data[thr].cmp + off, PAGE_SIZE);

                ret = swap_write_page(handle, page, &bio);
                if (ret)
                    goto out_finish;
            }
        }

        wait_event(crc->done, atomic_read(&crc->stop));
        atomic_set(&crc->stop, 0);
    }

out_finish:
    err2 = hib_wait_on_bio_chain(&bio);
    do_gettimeofday(&stop);
    if (!ret)
        ret = err2;
    if (!ret)
        printk(KERN_INFO "PM: Image saving done.\n");
    swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
out_clean:
    if (crc) {
        if (crc->thr)
            kthread_stop(crc->thr);
        kfree(crc);
    }
    if (data) {
        for (thr = 0; thr < nr_threads; thr++)
            if (data[thr].thr)
                kthread_stop(data[thr].thr);
        vfree(data);
    }
    if (page) free_page((unsigned long)page);

    return ret;
}

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

    pr_debug("PM: Free swap pages: %u\n", free_swap);

    required = PAGES_FOR_IO + nr_pages;
    return free_swap > required;
}

int swsusp_write(unsigned int flags)
{
    struct swap_map_handle handle;
    struct snapshot_handle snapshot;
    struct swsusp_info *header;
    unsigned long pages;
    int error;

    pages = snapshot_get_image_size();
    error = get_swap_writer(&handle);
    if (error) {
        printk(KERN_ERR "PM: Cannot get swap writer\n");
        return error;
    }
    if (flags & SF_NOCOMPRESS_MODE) {
        if (!enough_swap(pages, flags)) {
            printk(KERN_ERR "PM: Not enough free swap\n");
            error = -ENOSPC;
            goto out_finish;
        }
    }
    memset(&snapshot, 0, sizeof(struct snapshot_handle));
    error = snapshot_read_next(&snapshot);
    if (error < PAGE_SIZE) {
        if (error >= 0)
            error = -EFAULT;

        goto out_finish;
    }
    header = (struct swsusp_info *)data_of(snapshot);
    error = swap_write_page(&handle, header, NULL);
    if (!error) {
        error = (flags & SF_NOCOMPRESS_MODE) ?
            save_image(&handle, &snapshot, pages - 1) :
            save_image_lzo(&handle, &snapshot, pages - 1);
    }
out_finish:
    error = swap_writer_finish(&handle, flags, error);
    return error;
}

static void release_swap_reader(struct swap_map_handle *handle)
{
    struct swap_map_page_list *tmp;

    while (handle->maps) {
        if (handle->maps->map)
            free_page((unsigned long)handle->maps->map);
        tmp = handle->maps;
        handle->maps = handle->maps->next;
        kfree(tmp);
    }
    handle->cur = NULL;
}

static int get_swap_reader(struct swap_map_handle *handle,
        unsigned int *flags_p)
{
    int error;
    struct swap_map_page_list *tmp, *last;
    sector_t offset;

    *flags_p = swsusp_header->flags;

    if (!swsusp_header->image) /* how can this happen? */
        return -EINVAL;

    handle->cur = NULL;
    last = handle->maps = NULL;
    offset = swsusp_header->image;
    while (offset) {
        tmp = kmalloc(sizeof(*handle->maps), GFP_KERNEL);
        if (!tmp) {
            release_swap_reader(handle);
            return -ENOMEM;
        }
        memset(tmp, 0, sizeof(*tmp));
        if (!handle->maps)
            handle->maps = tmp;
        if (last)
            last->next = tmp;
        last = tmp;

        tmp->map = (struct swap_map_page *)
                   __get_free_page(__GFP_WAIT | __GFP_HIGH);
        if (!tmp->map) {
            release_swap_reader(handle);
            return -ENOMEM;
        }

        error = hib_bio_read_page(offset, tmp->map, NULL);
        if (error) {
            release_swap_reader(handle);
            return error;
        }
        offset = tmp->map->next_swap;
    }
    handle->k = 0;
    handle->cur = handle->maps->map;
    return 0;
}

static int swap_read_page(struct swap_map_handle *handle, void *buf,
                struct bio **bio_chain)
{
    sector_t offset;
    int error;
    struct swap_map_page_list *tmp;

    if (!handle->cur)
        return -EINVAL;
    offset = handle->cur->entries[handle->k];
    if (!offset)
        return -EFAULT;
    error = hib_bio_read_page(offset, buf, bio_chain);
    if (error)
        return error;
    if (++handle->k >= MAP_PAGE_ENTRIES) {
        handle->k = 0;
        free_page((unsigned long)handle->maps->map);
        tmp = handle->maps;
        handle->maps = handle->maps->next;
        kfree(tmp);
        if (!handle->maps)
            release_swap_reader(handle);
        else
            handle->cur = handle->maps->map;
    }
    return error;
}

static int swap_reader_finish(struct swap_map_handle *handle)
{
    release_swap_reader(handle);

    return 0;
}

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

    printk(KERN_INFO "PM: Loading image data pages (%u pages)...\n",
        nr_to_read);
    m = nr_to_read / 10;
    if (!m)
        m = 1;
    nr_pages = 0;
    bio = NULL;
    do_gettimeofday(&start);
    for ( ; ; ) {
        ret = snapshot_write_next(snapshot);
        if (ret <= 0)
            break;
        ret = swap_read_page(handle, data_of(*snapshot), &bio);
        if (ret)
            break;
        if (snapshot->sync_read)
            ret = hib_wait_on_bio_chain(&bio);
        if (ret)
            break;
        if (!(nr_pages % m))
            printk(KERN_INFO "PM: Image loading progress: %3d%%\n",
                   nr_pages / m * 10);
        nr_pages++;
    }
    err2 = hib_wait_on_bio_chain(&bio);
    do_gettimeofday(&stop);
    if (!ret)
        ret = err2;
    if (!ret) {
        printk(KERN_INFO "PM: Image loading done.\n");
        snapshot_write_finalize(snapshot);
        if (!snapshot_image_loaded(snapshot))
            ret = -ENODATA;
    }
    swsusp_show_speed(&start, &stop, nr_to_read, "Read");
    return ret;
}

struct dec_data {
    struct task_struct *thr;                  /* thread */
    atomic_t ready;                           /* ready to start flag */
    atomic_t stop;                            /* ready to stop flag */
    int ret;                                  /* return code */
    wait_queue_head_t go;                     /* start decompression */
    wait_queue_head_t done;                   /* decompression done */
    size_t unc_len;                           /* uncompressed length */
    size_t cmp_len;                           /* compressed length */
    unsigned char unc[LZO_UNC_SIZE];          /* uncompressed buffer */
    unsigned char cmp[LZO_CMP_SIZE];          /* compressed buffer */
};

static int lzo_decompress_threadfn(void *data)
{
    struct dec_data *d = data;

    while (1) {
        wait_event(d->go, atomic_read(&d->ready) ||
                          kthread_should_stop());
        if (kthread_should_stop()) {
            d->thr = NULL;
            d->ret = -1;
            atomic_set(&d->stop, 1);
            wake_up(&d->done);
            break;
        }
        atomic_set(&d->ready, 0);

        d->unc_len = LZO_UNC_SIZE;
        d->ret = lzo1x_decompress_safe(d->cmp + LZO_HEADER, d->cmp_len,
                                       d->unc, &d->unc_len);
        atomic_set(&d->stop, 1);
        wake_up(&d->done);
    }
    return 0;
}

static int load_image_lzo(struct swap_map_handle *handle,
                          struct snapshot_handle *snapshot,
                          unsigned int nr_to_read)
{
    unsigned int m;
    int ret = 0;
    int eof = 0;
    struct bio *bio;
    struct timeval start;
    struct timeval stop;
    unsigned nr_pages;
    size_t off;
    unsigned i, thr, run_threads, nr_threads;
    unsigned ring = 0, pg = 0, ring_size = 0,
             have = 0, want, need, asked = 0;
    unsigned long read_pages = 0;
    unsigned char **page = NULL;
    struct dec_data *data = NULL;
    struct crc_data *crc = NULL;

    /*
     * We'll limit the number of threads for decompression to limit memory
     * footprint.
     */
    nr_threads = num_online_cpus() - 1;
    nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);

    page = vmalloc(sizeof(*page) * LZO_MAX_RD_PAGES);
    if (!page) {
        printk(KERN_ERR "PM: Failed to allocate LZO page\n");
        ret = -ENOMEM;
        goto out_clean;
    }

    data = vmalloc(sizeof(*data) * nr_threads);
    if (!data) {
        printk(KERN_ERR "PM: Failed to allocate LZO data\n");
        ret = -ENOMEM;
        goto out_clean;
    }
    for (thr = 0; thr < nr_threads; thr++)
        memset(&data[thr], 0, offsetof(struct dec_data, go));

    crc = kmalloc(sizeof(*crc), GFP_KERNEL);
    if (!crc) {
        printk(KERN_ERR "PM: Failed to allocate crc\n");
        ret = -ENOMEM;
        goto out_clean;
    }
    memset(crc, 0, offsetof(struct crc_data, go));

    /*
     * Start the decompression threads.
     */
    for (thr = 0; thr < nr_threads; thr++) {
        init_waitqueue_head(&data[thr].go);
        init_waitqueue_head(&data[thr].done);

        data[thr].thr = kthread_run(lzo_decompress_threadfn,
                                    &data[thr],
                                    "image_decompress/%u", thr);
        if (IS_ERR(data[thr].thr)) {
            data[thr].thr = NULL;
            printk(KERN_ERR
                   "PM: Cannot start decompression threads\n");
            ret = -ENOMEM;
            goto out_clean;
        }
    }

    /*
     * Start the CRC32 thread.
     */
    init_waitqueue_head(&crc->go);
    init_waitqueue_head(&crc->done);

    handle->crc32 = 0;
    crc->crc32 = &handle->crc32;
    for (thr = 0; thr < nr_threads; thr++) {
        crc->unc[thr] = data[thr].unc;
        crc->unc_len[thr] = &data[thr].unc_len;
    }

    crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
    if (IS_ERR(crc->thr)) {
        crc->thr = NULL;
        printk(KERN_ERR "PM: Cannot start CRC32 thread\n");
        ret = -ENOMEM;
        goto out_clean;
    }

    /*
     * Set the number of pages for read buffering.
     * This is complete guesswork, because we'll only know the real
     * picture once prepare_image() is called, which is much later on
     * during the image load phase. We'll assume the worst case and
     * say that none of the image pages are from high memory.
     */
    if (low_free_pages() > snapshot_get_image_size())
        read_pages = (low_free_pages() - snapshot_get_image_size()) / 2;
    read_pages = clamp_val(read_pages, LZO_MIN_RD_PAGES, LZO_MAX_RD_PAGES);

    for (i = 0; i < read_pages; i++) {
        page[i] = (void *)__get_free_page(i < LZO_CMP_PAGES ?
                                          __GFP_WAIT | __GFP_HIGH :
                                          __GFP_WAIT | __GFP_NOWARN |
                                          __GFP_NORETRY);

        if (!page[i]) {
            if (i < LZO_CMP_PAGES) {
                ring_size = i;
                printk(KERN_ERR
                       "PM: Failed to allocate LZO pages\n");
                ret = -ENOMEM;
                goto out_clean;
            } else {
                break;
            }
        }
    }
    want = ring_size = i;

    printk(KERN_INFO
        "PM: Using %u thread(s) for decompression.\n"
        "PM: Loading and decompressing image data (%u pages)...\n",
        nr_threads, nr_to_read);
    m = nr_to_read / 10;
    if (!m)
        m = 1;
    nr_pages = 0;
    bio = NULL;
    do_gettimeofday(&start);

    ret = snapshot_write_next(snapshot);
    if (ret <= 0)
        goto out_finish;

    for(;;) {
        for (i = 0; !eof && i < want; i++) {
            ret = swap_read_page(handle, page[ring], &bio);
            if (ret) {
                /*
                 * On real read error, finish. On end of data,
                 * set EOF flag and just exit the read loop.
                 */
                if (handle->cur &&
                    handle->cur->entries[handle->k]) {
                    goto out_finish;
                } else {
                    eof = 1;
                    break;
                }
            }
            if (++ring >= ring_size)
                ring = 0;
        }
        asked += i;
        want -= i;

        /*
         * We are out of data, wait for some more.
         */
        if (!have) {
            if (!asked)
                break;

            ret = hib_wait_on_bio_chain(&bio);
            if (ret)
                goto out_finish;
            have += asked;
            asked = 0;
            if (eof)
                eof = 2;
        }

        if (crc->run_threads) {
            wait_event(crc->done, atomic_read(&crc->stop));
            atomic_set(&crc->stop, 0);
            crc->run_threads = 0;
        }

        for (thr = 0; have && thr < nr_threads; thr++) {
            data[thr].cmp_len = *(size_t *)page[pg];
            if (unlikely(!data[thr].cmp_len ||
                         data[thr].cmp_len >
                         lzo1x_worst_compress(LZO_UNC_SIZE))) {
                printk(KERN_ERR
                       "PM: Invalid LZO compressed length\n");
                ret = -1;
                goto out_finish;
            }

            need = DIV_ROUND_UP(data[thr].cmp_len + LZO_HEADER,
                                PAGE_SIZE);
            if (need > have) {
                if (eof > 1) {
                    ret = -1;
                    goto out_finish;
                }
                break;
            }

            for (off = 0;
                 off < LZO_HEADER + data[thr].cmp_len;
                 off += PAGE_SIZE) {
                memcpy(data[thr].cmp + off,
                       page[pg], PAGE_SIZE);
                have--;
                want++;
                if (++pg >= ring_size)
                    pg = 0;
            }

            atomic_set(&data[thr].ready, 1);
            wake_up(&data[thr].go);
        }

        /*
         * Wait for more data while we are decompressing.
         */
        if (have < LZO_CMP_PAGES && asked) {
            ret = hib_wait_on_bio_chain(&bio);
            if (ret)
                goto out_finish;
            have += asked;
            asked = 0;
            if (eof)
                eof = 2;
        }

        for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
            wait_event(data[thr].done,
                       atomic_read(&data[thr].stop));
            atomic_set(&data[thr].stop, 0);

            ret = data[thr].ret;

            if (ret < 0) {
                printk(KERN_ERR
                       "PM: LZO decompression failed\n");
                goto out_finish;
            }

            if (unlikely(!data[thr].unc_len ||
                         data[thr].unc_len > LZO_UNC_SIZE ||
                         data[thr].unc_len & (PAGE_SIZE - 1))) {
                printk(KERN_ERR
                       "PM: Invalid LZO uncompressed length\n");
                ret = -1;
                goto out_finish;
            }

            for (off = 0;
                 off < data[thr].unc_len; off += PAGE_SIZE) {
                memcpy(data_of(*snapshot),
                       data[thr].unc + off, PAGE_SIZE);

                if (!(nr_pages % m))
                    printk(KERN_INFO
                           "PM: Image loading progress: "
                           "%3d%%\n",
                           nr_pages / m * 10);
                nr_pages++;

                ret = snapshot_write_next(snapshot);
                if (ret <= 0) {
                    crc->run_threads = thr + 1;
                    atomic_set(&crc->ready, 1);
                    wake_up(&crc->go);
                    goto out_finish;
                }
            }
        }

        crc->run_threads = thr;
        atomic_set(&crc->ready, 1);
        wake_up(&crc->go);
    }

out_finish:
    if (crc->run_threads) {
        wait_event(crc->done, atomic_read(&crc->stop));
        atomic_set(&crc->stop, 0);
    }
    do_gettimeofday(&stop);
    if (!ret) {
        printk(KERN_INFO "PM: Image loading done.\n");
        snapshot_write_finalize(snapshot);
        if (!snapshot_image_loaded(snapshot))
            ret = -ENODATA;
        if (!ret) {
            if (swsusp_header->flags & SF_CRC32_MODE) {
                if(handle->crc32 != swsusp_header->crc32) {
                    printk(KERN_ERR
                           "PM: Invalid image CRC32!\n");
                    ret = -ENODATA;
                }
            }
        }
    }
    swsusp_show_speed(&start, &stop, nr_to_read, "Read");
out_clean:
    for (i = 0; i < ring_size; i++)
        free_page((unsigned long)page[i]);
    if (crc) {
        if (crc->thr)
            kthread_stop(crc->thr);
        kfree(crc);
    }
    if (data) {
        for (thr = 0; thr < nr_threads; thr++)
            if (data[thr].thr)
                kthread_stop(data[thr].thr);
        vfree(data);
    }
    if (page) vfree(page);

    return ret;
}

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

    memset(&snapshot, 0, sizeof(struct snapshot_handle));
    error = snapshot_write_next(&snapshot);
    if (error < PAGE_SIZE)
        return error < 0 ? error : -EFAULT;
    header = (struct swsusp_info *)data_of(snapshot);
    error = get_swap_reader(&handle, flags_p);
    if (error)
        goto end;
    if (!error)
        error = swap_read_page(&handle, header, NULL);
    if (!error) {
        error = (*flags_p & SF_NOCOMPRESS_MODE) ?
            load_image(&handle, &snapshot, header->pages - 1) :
            load_image_lzo(&handle, &snapshot, header->pages - 1);
    }
    swap_reader_finish(&handle);
end:
    if (!error)
        pr_debug("PM: Image successfully loaded\n");
    else
        pr_debug("PM: Error %d resuming\n", error);
    return error;
}

int swsusp_check(void)
{
    int error;

    hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device,
                        FMODE_READ, NULL);
    if (!IS_ERR(hib_resume_bdev)) {
        set_blocksize(hib_resume_bdev, PAGE_SIZE);
        clear_page(swsusp_header);
        error = hib_bio_read_page(swsusp_resume_block,
                    swsusp_header, NULL);
        if (error)
            goto put;

        if (!memcmp(HIBERNATE_SIG, swsusp_header->sig, 10)) {
            memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
            /* Reset swap signature now */
            error = hib_bio_write_page(swsusp_resume_block,
                        swsusp_header, NULL);
        } else {
            error = -EINVAL;
        }

put:
        if (error)
            blkdev_put(hib_resume_bdev, FMODE_READ);
        else
            pr_debug("PM: Image signature found, resuming\n");
    } else {
        error = PTR_ERR(hib_resume_bdev);
    }

    if (error)
        pr_debug("PM: Image not found (code %d)\n", error);

    return error;
}

void swsusp_close(fmode_t mode)
{
    if (IS_ERR(hib_resume_bdev)) {
        pr_debug("PM: Image device not initialised\n");
        return;
    }

    blkdev_put(hib_resume_bdev, mode);
}

#ifdef CONFIG_SUSPEND
int swsusp_unmark(void)
{
    int error;

    hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
    if (!memcmp(HIBERNATE_SIG,swsusp_header->sig, 10)) {
        memcpy(swsusp_header->sig,swsusp_header->orig_sig, 10);
        error = hib_bio_write_page(swsusp_resume_block,
                    swsusp_header, NULL);
    } else {
        printk(KERN_ERR "PM: Cannot find swsusp signature!\n");
        error = -ENODEV;
    }

    /*
     * We just returned from suspend, we don't need the image any more.
     */
    free_all_swap_pages(root_swap);

    return error;
}
#endif

static int swsusp_header_init(void)
{
    swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
    if (!swsusp_header)
        panic("Could not allocate memory for swsusp_header\n");
    return 0;
}

core_initcall(swsusp_header_init);