![Andrew Morton](/assets/img/avatar_default.png)
kernel/power/swap.c: In function 'swsusp_write': kernel/power/swap.c:275: warning: 'start' may be used uninitialized in this function gcc isn't smart enough, so help it. Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
546 lines
13 KiB
C
546 lines
13 KiB
C
/*
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* linux/kernel/power/swap.c
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*
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* This file provides functions for reading the suspend image from
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* and writing it to a swap partition.
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*
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* Copyright (C) 1998,2001-2005 Pavel Machek <pavel@suse.cz>
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* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
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*
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* This file is released under the GPLv2.
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*
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*/
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#include <linux/module.h>
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#include <linux/smp_lock.h>
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#include <linux/file.h>
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#include <linux/utsname.h>
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#include <linux/version.h>
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#include <linux/delay.h>
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#include <linux/bitops.h>
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#include <linux/genhd.h>
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#include <linux/device.h>
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#include <linux/buffer_head.h>
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#include <linux/bio.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/pm.h>
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#include "power.h"
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extern char resume_file[];
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#define SWSUSP_SIG "S1SUSPEND"
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static struct swsusp_header {
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char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
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swp_entry_t image;
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char orig_sig[10];
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char sig[10];
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} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;
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/*
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* Saving part...
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*/
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static unsigned short root_swap = 0xffff;
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static int mark_swapfiles(swp_entry_t start)
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{
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int error;
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rw_swap_page_sync(READ,
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swp_entry(root_swap, 0),
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virt_to_page((unsigned long)&swsusp_header));
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if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
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!memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
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memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
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memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
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swsusp_header.image = start;
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error = rw_swap_page_sync(WRITE,
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swp_entry(root_swap, 0),
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virt_to_page((unsigned long)
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&swsusp_header));
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} else {
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pr_debug("swsusp: Partition is not swap space.\n");
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error = -ENODEV;
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}
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return error;
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}
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/**
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* swsusp_swap_check - check if the resume device is a swap device
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* and get its index (if so)
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*/
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static int swsusp_swap_check(void) /* This is called before saving image */
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{
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int res = swap_type_of(swsusp_resume_device);
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if (res >= 0) {
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root_swap = res;
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return 0;
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}
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return res;
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}
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/**
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* write_page - Write one page to given swap location.
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* @buf: Address we're writing.
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* @offset: Offset of the swap page we're writing to.
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*/
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static int write_page(void *buf, unsigned long offset)
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{
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swp_entry_t entry;
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int error = -ENOSPC;
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if (offset) {
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entry = swp_entry(root_swap, offset);
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error = rw_swap_page_sync(WRITE, entry, virt_to_page(buf));
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}
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return error;
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}
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/*
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* The swap map is a data structure used for keeping track of each page
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* written to a swap partition. It consists of many swap_map_page
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* structures that contain each an array of MAP_PAGE_SIZE swap entries.
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* These structures are stored on the swap and linked together with the
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* help of the .next_swap member.
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*
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* The swap map is created during suspend. The swap map pages are
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* allocated and populated one at a time, so we only need one memory
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* page to set up the entire structure.
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*
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* During resume we also only need to use one swap_map_page structure
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* at a time.
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*/
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#define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(long) - 1)
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struct swap_map_page {
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unsigned long entries[MAP_PAGE_ENTRIES];
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unsigned long next_swap;
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};
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/**
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* The swap_map_handle structure is used for handling swap in
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* a file-alike way
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*/
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struct swap_map_handle {
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struct swap_map_page *cur;
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unsigned long cur_swap;
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struct bitmap_page *bitmap;
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unsigned int k;
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};
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static void release_swap_writer(struct swap_map_handle *handle)
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{
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if (handle->cur)
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free_page((unsigned long)handle->cur);
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handle->cur = NULL;
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if (handle->bitmap)
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free_bitmap(handle->bitmap);
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handle->bitmap = NULL;
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}
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static int get_swap_writer(struct swap_map_handle *handle)
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{
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handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
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if (!handle->cur)
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return -ENOMEM;
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handle->bitmap = alloc_bitmap(count_swap_pages(root_swap, 0));
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if (!handle->bitmap) {
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release_swap_writer(handle);
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return -ENOMEM;
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}
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handle->cur_swap = alloc_swap_page(root_swap, handle->bitmap);
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if (!handle->cur_swap) {
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release_swap_writer(handle);
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return -ENOSPC;
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}
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handle->k = 0;
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return 0;
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}
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static int swap_write_page(struct swap_map_handle *handle, void *buf)
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{
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int error;
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unsigned long offset;
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if (!handle->cur)
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return -EINVAL;
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offset = alloc_swap_page(root_swap, handle->bitmap);
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error = write_page(buf, offset);
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if (error)
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return error;
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handle->cur->entries[handle->k++] = offset;
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if (handle->k >= MAP_PAGE_ENTRIES) {
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offset = alloc_swap_page(root_swap, handle->bitmap);
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if (!offset)
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return -ENOSPC;
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handle->cur->next_swap = offset;
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error = write_page(handle->cur, handle->cur_swap);
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if (error)
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return error;
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memset(handle->cur, 0, PAGE_SIZE);
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handle->cur_swap = offset;
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handle->k = 0;
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}
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return 0;
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}
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static int flush_swap_writer(struct swap_map_handle *handle)
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{
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if (handle->cur && handle->cur_swap)
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return write_page(handle->cur, handle->cur_swap);
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else
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return -EINVAL;
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}
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/**
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* save_image - save the suspend image data
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*/
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static int save_image(struct swap_map_handle *handle,
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struct snapshot_handle *snapshot,
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unsigned int nr_pages)
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{
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unsigned int m;
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int ret;
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int error = 0;
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printk("Saving image data pages (%u pages) ... ", nr_pages);
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m = nr_pages / 100;
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if (!m)
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m = 1;
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nr_pages = 0;
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do {
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ret = snapshot_read_next(snapshot, PAGE_SIZE);
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if (ret > 0) {
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error = swap_write_page(handle, data_of(*snapshot));
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if (error)
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break;
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if (!(nr_pages % m))
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printk("\b\b\b\b%3d%%", nr_pages / m);
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nr_pages++;
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}
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} while (ret > 0);
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if (!error)
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printk("\b\b\b\bdone\n");
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return error;
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}
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/**
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* enough_swap - Make sure we have enough swap to save the image.
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*
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* Returns TRUE or FALSE after checking the total amount of swap
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* space avaiable from the resume partition.
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*/
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static int enough_swap(unsigned int nr_pages)
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{
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unsigned int free_swap = count_swap_pages(root_swap, 1);
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pr_debug("swsusp: free swap pages: %u\n", free_swap);
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return free_swap > (nr_pages + PAGES_FOR_IO +
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(nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
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}
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/**
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* swsusp_write - Write entire image and metadata.
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*
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* It is important _NOT_ to umount filesystems at this point. We want
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* them synced (in case something goes wrong) but we DO not want to mark
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* filesystem clean: it is not. (And it does not matter, if we resume
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* correctly, we'll mark system clean, anyway.)
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*/
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int swsusp_write(void)
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{
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struct swap_map_handle handle;
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struct snapshot_handle snapshot;
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struct swsusp_info *header;
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int error;
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if ((error = swsusp_swap_check())) {
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printk(KERN_ERR "swsusp: Cannot find swap device, try swapon -a.\n");
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return error;
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}
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memset(&snapshot, 0, sizeof(struct snapshot_handle));
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error = snapshot_read_next(&snapshot, PAGE_SIZE);
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if (error < PAGE_SIZE)
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return error < 0 ? error : -EFAULT;
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header = (struct swsusp_info *)data_of(snapshot);
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if (!enough_swap(header->pages)) {
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printk(KERN_ERR "swsusp: Not enough free swap\n");
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return -ENOSPC;
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}
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error = get_swap_writer(&handle);
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if (!error) {
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unsigned long start = handle.cur_swap;
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error = swap_write_page(&handle, header);
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if (!error)
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error = save_image(&handle, &snapshot,
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header->pages - 1);
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if (!error) {
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flush_swap_writer(&handle);
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printk("S");
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error = mark_swapfiles(swp_entry(root_swap, start));
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printk("|\n");
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}
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}
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if (error)
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free_all_swap_pages(root_swap, handle.bitmap);
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release_swap_writer(&handle);
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return error;
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}
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/*
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* Using bio to read from swap.
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* This code requires a bit more work than just using buffer heads
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* but, it is the recommended way for 2.5/2.6.
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* The following are to signal the beginning and end of I/O. Bios
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* finish asynchronously, while we want them to happen synchronously.
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* A simple atomic_t, and a wait loop take care of this problem.
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*/
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static atomic_t io_done = ATOMIC_INIT(0);
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static int end_io(struct bio *bio, unsigned int num, int err)
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{
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if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
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panic("I/O error reading memory image");
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atomic_set(&io_done, 0);
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return 0;
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}
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static struct block_device *resume_bdev;
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/**
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* submit - submit BIO request.
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* @rw: READ or WRITE.
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* @off physical offset of page.
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* @page: page we're reading or writing.
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*
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* Straight from the textbook - allocate and initialize the bio.
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* If we're writing, make sure the page is marked as dirty.
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* Then submit it and wait.
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*/
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static int submit(int rw, pgoff_t page_off, void *page)
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{
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int error = 0;
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struct bio *bio;
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bio = bio_alloc(GFP_ATOMIC, 1);
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if (!bio)
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return -ENOMEM;
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bio->bi_sector = page_off * (PAGE_SIZE >> 9);
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bio->bi_bdev = resume_bdev;
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bio->bi_end_io = end_io;
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if (bio_add_page(bio, virt_to_page(page), PAGE_SIZE, 0) < PAGE_SIZE) {
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printk("swsusp: ERROR: adding page to bio at %ld\n",page_off);
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error = -EFAULT;
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goto Done;
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}
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atomic_set(&io_done, 1);
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submit_bio(rw | (1 << BIO_RW_SYNC), bio);
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while (atomic_read(&io_done))
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yield();
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if (rw == READ)
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bio_set_pages_dirty(bio);
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Done:
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bio_put(bio);
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return error;
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}
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static int bio_read_page(pgoff_t page_off, void *page)
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{
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return submit(READ, page_off, page);
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}
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static int bio_write_page(pgoff_t page_off, void *page)
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{
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return submit(WRITE, page_off, page);
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}
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/**
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* The following functions allow us to read data using a swap map
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* in a file-alike way
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*/
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static void release_swap_reader(struct swap_map_handle *handle)
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{
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if (handle->cur)
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free_page((unsigned long)handle->cur);
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handle->cur = NULL;
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}
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static int get_swap_reader(struct swap_map_handle *handle,
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swp_entry_t start)
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{
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int error;
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if (!swp_offset(start))
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return -EINVAL;
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handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_ATOMIC);
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if (!handle->cur)
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return -ENOMEM;
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error = bio_read_page(swp_offset(start), handle->cur);
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if (error) {
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release_swap_reader(handle);
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return error;
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}
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handle->k = 0;
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return 0;
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}
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static int swap_read_page(struct swap_map_handle *handle, void *buf)
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{
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unsigned long offset;
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int error;
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if (!handle->cur)
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return -EINVAL;
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offset = handle->cur->entries[handle->k];
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if (!offset)
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return -EFAULT;
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error = bio_read_page(offset, buf);
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if (error)
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return error;
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if (++handle->k >= MAP_PAGE_ENTRIES) {
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handle->k = 0;
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offset = handle->cur->next_swap;
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if (!offset)
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release_swap_reader(handle);
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else
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error = bio_read_page(offset, handle->cur);
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}
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return error;
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}
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/**
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* load_image - load the image using the swap map handle
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* @handle and the snapshot handle @snapshot
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* (assume there are @nr_pages pages to load)
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*/
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static int load_image(struct swap_map_handle *handle,
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struct snapshot_handle *snapshot,
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unsigned int nr_pages)
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{
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unsigned int m;
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int ret;
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int error = 0;
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printk("Loading image data pages (%u pages) ... ", nr_pages);
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m = nr_pages / 100;
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if (!m)
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m = 1;
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nr_pages = 0;
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do {
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ret = snapshot_write_next(snapshot, PAGE_SIZE);
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if (ret > 0) {
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error = swap_read_page(handle, data_of(*snapshot));
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if (error)
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break;
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if (!(nr_pages % m))
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printk("\b\b\b\b%3d%%", nr_pages / m);
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nr_pages++;
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}
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} while (ret > 0);
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if (!error) {
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printk("\b\b\b\bdone\n");
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if (!snapshot_image_loaded(snapshot))
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error = -ENODATA;
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}
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return error;
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}
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int swsusp_read(void)
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{
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int error;
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struct swap_map_handle handle;
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struct snapshot_handle snapshot;
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struct swsusp_info *header;
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if (IS_ERR(resume_bdev)) {
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pr_debug("swsusp: block device not initialised\n");
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return PTR_ERR(resume_bdev);
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}
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memset(&snapshot, 0, sizeof(struct snapshot_handle));
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error = snapshot_write_next(&snapshot, PAGE_SIZE);
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if (error < PAGE_SIZE)
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return error < 0 ? error : -EFAULT;
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header = (struct swsusp_info *)data_of(snapshot);
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error = get_swap_reader(&handle, swsusp_header.image);
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if (!error)
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error = swap_read_page(&handle, header);
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if (!error)
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error = load_image(&handle, &snapshot, header->pages - 1);
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release_swap_reader(&handle);
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blkdev_put(resume_bdev);
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if (!error)
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pr_debug("swsusp: Reading resume file was successful\n");
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else
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pr_debug("swsusp: Error %d resuming\n", error);
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return error;
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}
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/**
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* swsusp_check - Check for swsusp signature in the resume device
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*/
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int swsusp_check(void)
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{
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int error;
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resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
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if (!IS_ERR(resume_bdev)) {
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set_blocksize(resume_bdev, PAGE_SIZE);
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memset(&swsusp_header, 0, sizeof(swsusp_header));
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if ((error = bio_read_page(0, &swsusp_header)))
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return error;
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if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
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memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
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/* Reset swap signature now */
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error = bio_write_page(0, &swsusp_header);
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} else {
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return -EINVAL;
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}
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if (error)
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blkdev_put(resume_bdev);
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else
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pr_debug("swsusp: Signature found, resuming\n");
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} else {
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error = PTR_ERR(resume_bdev);
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}
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if (error)
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pr_debug("swsusp: Error %d check for resume file\n", error);
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return error;
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}
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/**
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* swsusp_close - close swap device.
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*/
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void swsusp_close(void)
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{
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if (IS_ERR(resume_bdev)) {
|
|
pr_debug("swsusp: block device not initialised\n");
|
|
return;
|
|
}
|
|
|
|
blkdev_put(resume_bdev);
|
|
}
|