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

Move the swap-writing/reading code of swsusp to a separate file.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 544 insertions, 0 deletions

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
new file mode 100644
index 000000000000..9177f3f73a6c
--- /dev/null
+++ b/kernel/power/swap.c
@@ -0,0 +1,544 @@
+/*
+ * 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);
+}