[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>
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
new file mode 100644
index 0000000..9177f3f
--- /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);
+}