1 files changed, 1433 insertions, 0 deletions

diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
new file mode 100644
index 000000000000..ae5bebc3b18f
--- /dev/null
+++ b/kernel/power/swsusp.c
@@ -0,0 +1,1433 @@
+/*
+ * linux/kernel/power/swsusp.c
+ *
+ * This file is to realize architecture-independent
+ * machine suspend feature using pretty near only high-level routines
+ *
+ * Copyright (C) 1998-2001 Gabor Kuti <seasons@fornax.hu>
+ * Copyright (C) 1998,2001-2004 Pavel Machek <pavel@suse.cz>
+ *
+ * This file is released under the GPLv2.
+ *
+ * I'd like to thank the following people for their work:
+ * 
+ * Pavel Machek <pavel@ucw.cz>:
+ * Modifications, defectiveness pointing, being with me at the very beginning,
+ * suspend to swap space, stop all tasks. Port to 2.4.18-ac and 2.5.17.
+ *
+ * Steve Doddi <dirk@loth.demon.co.uk>: 
+ * Support the possibility of hardware state restoring.
+ *
+ * Raph <grey.havens@earthling.net>:
+ * Support for preserving states of network devices and virtual console
+ * (including X and svgatextmode)
+ *
+ * Kurt Garloff <garloff@suse.de>:
+ * Straightened the critical function in order to prevent compilers from
+ * playing tricks with local variables.
+ *
+ * Andreas Mohr <a.mohr@mailto.de>
+ *
+ * Alex Badea <vampire@go.ro>:
+ * Fixed runaway init
+ *
+ * More state savers are welcome. Especially for the scsi layer...
+ *
+ * For TODOs,FIXMEs also look in Documentation/power/swsusp.txt
+ */
+
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/suspend.h>
+#include <linux/smp_lock.h>
+#include <linux/file.h>
+#include <linux/utsname.h>
+#include <linux/version.h>
+#include <linux/delay.h>
+#include <linux/reboot.h>
+#include <linux/bitops.h>
+#include <linux/vt_kern.h>
+#include <linux/kbd_kern.h>
+#include <linux/keyboard.h>
+#include <linux/spinlock.h>
+#include <linux/genhd.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/swap.h>
+#include <linux/pm.h>
+#include <linux/device.h>
+#include <linux/buffer_head.h>
+#include <linux/swapops.h>
+#include <linux/bootmem.h>
+#include <linux/syscalls.h>
+#include <linux/console.h>
+#include <linux/highmem.h>
+#include <linux/bio.h>
+
+#include <asm/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/io.h>
+
+#include "power.h"
+
+/* References to section boundaries */
+extern const void __nosave_begin, __nosave_end;
+
+/* Variables to be preserved over suspend */
+static int nr_copy_pages_check;
+
+extern char resume_file[];
+
+/* Local variables that should not be affected by save */
+unsigned int nr_copy_pages __nosavedata = 0;
+
+/* Suspend pagedir is allocated before final copy, therefore it
+   must be freed after resume 
+
+   Warning: this is evil. There are actually two pagedirs at time of
+   resume. One is "pagedir_save", which is empty frame allocated at
+   time of suspend, that must be freed. Second is "pagedir_nosave", 
+   allocated at time of resume, that travels through memory not to
+   collide with anything.
+
+   Warning: this is even more evil than it seems. Pagedirs this file
+   talks about are completely different from page directories used by
+   MMU hardware.
+ */
+suspend_pagedir_t *pagedir_nosave __nosavedata = NULL;
+static suspend_pagedir_t *pagedir_save;
+
+#define SWSUSP_SIG      "S1SUSPEND"
+
+static struct swsusp_header {
+        char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
+        swp_entry_t swsusp_info;
+        char    orig_sig[10];
+        char    sig[10];
+} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;
+
+static struct swsusp_info swsusp_info;
+
+/*
+ * XXX: We try to keep some more pages free so that I/O operations succeed
+ * without paging. Might this be more?
+ */
+#define PAGES_FOR_IO    512
+
+/*
+ * Saving part...
+ */
+
+/* We memorize in swapfile_used what swap devices are used for suspension */
+#define SWAPFILE_UNUSED    0
+#define SWAPFILE_SUSPEND   1    /* This is the suspending device */
+#define SWAPFILE_IGNORED   2    /* Those are other swap devices ignored for suspension */
+
+static unsigned short swapfile_used[MAX_SWAPFILES];
+static unsigned short root_swap;
+
+static int mark_swapfiles(swp_entry_t prev)
+{
+        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.swsusp_info = prev;
+                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;
+}
+
+/*
+ * Check whether the swap device is the specified resume
+ * device, irrespective of whether they are specified by
+ * identical names.
+ *
+ * (Thus, device inode aliasing is allowed.  You can say /dev/hda4
+ * instead of /dev/ide/host0/bus0/target0/lun0/part4 [if using devfs]
+ * and they'll be considered the same device.  This is *necessary* for
+ * devfs, since the resume code can only recognize the form /dev/hda4,
+ * but the suspend code would see the long name.)
+ */
+static int is_resume_device(const struct swap_info_struct *swap_info)
+{
+        struct file *file = swap_info->swap_file;
+        struct inode *inode = file->f_dentry->d_inode;
+
+        return S_ISBLK(inode->i_mode) &&
+                swsusp_resume_device == MKDEV(imajor(inode), iminor(inode));
+}
+
+static int swsusp_swap_check(void) /* This is called before saving image */
+{
+        int i, len;
+        
+        len=strlen(resume_file);
+        root_swap = 0xFFFF;
+        
+        swap_list_lock();
+        for(i=0; i<MAX_SWAPFILES; i++) {
+                if (swap_info[i].flags == 0) {
+                        swapfile_used[i]=SWAPFILE_UNUSED;
+                } else {
+                        if(!len) {
+                                printk(KERN_WARNING "resume= option should be used to set suspend device" );
+                                if(root_swap == 0xFFFF) {
+                                        swapfile_used[i] = SWAPFILE_SUSPEND;
+                                        root_swap = i;
+                                } else
+                                        swapfile_used[i] = SWAPFILE_IGNORED;                              
+                        } else {
+                                /* we ignore all swap devices that are not the resume_file */
+                                if (is_resume_device(&swap_info[i])) {
+                                        swapfile_used[i] = SWAPFILE_SUSPEND;
+                                        root_swap = i;
+                                } else {
+                                        swapfile_used[i] = SWAPFILE_IGNORED;
+                                }
+                        }
+                }
+        }
+        swap_list_unlock();
+        return (root_swap != 0xffff) ? 0 : -ENODEV;
+}
+
+/**
+ * This is called after saving image so modification
+ * will be lost after resume... and that's what we want.
+ * we make the device unusable. A new call to
+ * lock_swapdevices can unlock the devices. 
+ */
+static void lock_swapdevices(void)
+{
+        int i;
+
+        swap_list_lock();
+        for(i = 0; i< MAX_SWAPFILES; i++)
+                if(swapfile_used[i] == SWAPFILE_IGNORED) {
+                        swap_info[i].flags ^= 0xFF;
+                }
+        swap_list_unlock();
+}
+
+/**
+ *      write_swap_page - Write one page to a fresh swap location.
+ *      @addr:  Address we're writing.
+ *      @loc:   Place to store the entry we used.
+ *
+ *      Allocate a new swap entry and 'sync' it. Note we discard -EIO
+ *      errors. That is an artifact left over from swsusp. It did not 
+ *      check the return of rw_swap_page_sync() at all, since most pages
+ *      written back to swap would return -EIO.
+ *      This is a partial improvement, since we will at least return other
+ *      errors, though we need to eventually fix the damn code.
+ */
+static int write_page(unsigned long addr, swp_entry_t * loc)
+{
+        swp_entry_t entry;
+        int error = 0;
+
+        entry = get_swap_page();
+        if (swp_offset(entry) && 
+            swapfile_used[swp_type(entry)] == SWAPFILE_SUSPEND) {
+                error = rw_swap_page_sync(WRITE, entry,
+                                          virt_to_page(addr));
+                if (error == -EIO)
+                        error = 0;
+                if (!error)
+                        *loc = entry;
+        } else
+                error = -ENOSPC;
+        return error;
+}
+
+/**
+ *      data_free - Free the swap entries used by the saved image.
+ *
+ *      Walk the list of used swap entries and free each one. 
+ *      This is only used for cleanup when suspend fails.
+ */
+static void data_free(void)
+{
+        swp_entry_t entry;
+        int i;
+
+        for (i = 0; i < nr_copy_pages; i++) {
+                entry = (pagedir_nosave + i)->swap_address;
+                if (entry.val)
+                        swap_free(entry);
+                else
+                        break;
+                (pagedir_nosave + i)->swap_address = (swp_entry_t){0};
+        }
+}
+
+/**
+ *      data_write - Write saved image to swap.
+ *
+ *      Walk the list of pages in the image and sync each one to swap.
+ */
+static int data_write(void)
+{
+        int error = 0, i = 0;
+        unsigned int mod = nr_copy_pages / 100;
+        struct pbe *p;
+
+        if (!mod)
+                mod = 1;
+
+        printk( "Writing data to swap (%d pages)...     ", nr_copy_pages );
+        for_each_pbe(p, pagedir_nosave) {
+                if (!(i%mod))
+                        printk( "\b\b\b\b%3d%%", i / mod );
+                if ((error = write_page(p->address, &(p->swap_address))))
+                        return error;
+                i++;
+        }
+        printk("\b\b\b\bdone\n");
+        return error;
+}
+
+static void dump_info(void)
+{
+        pr_debug(" swsusp: Version: %u\n",swsusp_info.version_code);
+        pr_debug(" swsusp: Num Pages: %ld\n",swsusp_info.num_physpages);
+        pr_debug(" swsusp: UTS Sys: %s\n",swsusp_info.uts.sysname);
+        pr_debug(" swsusp: UTS Node: %s\n",swsusp_info.uts.nodename);
+        pr_debug(" swsusp: UTS Release: %s\n",swsusp_info.uts.release);
+        pr_debug(" swsusp: UTS Version: %s\n",swsusp_info.uts.version);
+        pr_debug(" swsusp: UTS Machine: %s\n",swsusp_info.uts.machine);
+        pr_debug(" swsusp: UTS Domain: %s\n",swsusp_info.uts.domainname);
+        pr_debug(" swsusp: CPUs: %d\n",swsusp_info.cpus);
+        pr_debug(" swsusp: Image: %ld Pages\n",swsusp_info.image_pages);
+        pr_debug(" swsusp: Pagedir: %ld Pages\n",swsusp_info.pagedir_pages);
+}
+
+static void init_header(void)
+{
+        memset(&swsusp_info, 0, sizeof(swsusp_info));
+        swsusp_info.version_code = LINUX_VERSION_CODE;
+        swsusp_info.num_physpages = num_physpages;
+        memcpy(&swsusp_info.uts, &system_utsname, sizeof(system_utsname));
+
+        swsusp_info.suspend_pagedir = pagedir_nosave;
+        swsusp_info.cpus = num_online_cpus();
+        swsusp_info.image_pages = nr_copy_pages;
+}
+
+static int close_swap(void)
+{
+        swp_entry_t entry;
+        int error;
+
+        dump_info();
+        error = write_page((unsigned long)&swsusp_info, &entry);
+        if (!error) { 
+                printk( "S" );
+                error = mark_swapfiles(entry);
+                printk( "|\n" );
+        }
+        return error;
+}
+
+/**
+ *      free_pagedir_entries - Free pages used by the page directory.
+ *
+ *      This is used during suspend for error recovery.
+ */
+
+static void free_pagedir_entries(void)
+{
+        int i;
+
+        for (i = 0; i < swsusp_info.pagedir_pages; i++)
+                swap_free(swsusp_info.pagedir[i]);
+}
+
+
+/**
+ *      write_pagedir - Write the array of pages holding the page directory.
+ *      @last:  Last swap entry we write (needed for header).
+ */
+
+static int write_pagedir(void)
+{
+        int error = 0;
+        unsigned n = 0;
+        struct pbe * pbe;
+
+        printk( "Writing pagedir...");
+        for_each_pb_page(pbe, pagedir_nosave) {
+                if ((error = write_page((unsigned long)pbe, &swsusp_info.pagedir[n++])))
+                        return error;
+        }
+
+        swsusp_info.pagedir_pages = n;
+        printk("done (%u pages)\n", n);
+        return error;
+}
+
+/**
+ *      write_suspend_image - Write entire image and metadata.
+ *
+ */
+
+static int write_suspend_image(void)
+{
+        int error;
+
+        init_header();
+        if ((error = data_write()))
+                goto FreeData;
+
+        if ((error = write_pagedir()))
+                goto FreePagedir;
+
+        if ((error = close_swap()))
+                goto FreePagedir;
+ Done:
+        return error;
+ FreePagedir:
+        free_pagedir_entries();
+ FreeData:
+        data_free();
+        goto Done;
+}
+
+
+#ifdef CONFIG_HIGHMEM
+struct highmem_page {
+        char *data;
+        struct page *page;
+        struct highmem_page *next;
+};
+
+static struct highmem_page *highmem_copy;
+
+static int save_highmem_zone(struct zone *zone)
+{
+        unsigned long zone_pfn;
+        mark_free_pages(zone);
+        for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
+                struct page *page;
+                struct highmem_page *save;
+                void *kaddr;
+                unsigned long pfn = zone_pfn + zone->zone_start_pfn;
+
+                if (!(pfn%1000))
+                        printk(".");
+                if (!pfn_valid(pfn))
+                        continue;
+                page = pfn_to_page(pfn);
+                /*
+                 * This condition results from rvmalloc() sans vmalloc_32()
+                 * and architectural memory reservations. This should be
+                 * corrected eventually when the cases giving rise to this
+                 * are better understood.
+                 */
+                if (PageReserved(page)) {
+                        printk("highmem reserved page?!\n");
+                        continue;
+                }
+                BUG_ON(PageNosave(page));
+                if (PageNosaveFree(page))
+                        continue;
+                save = kmalloc(sizeof(struct highmem_page), GFP_ATOMIC);
+                if (!save)
+                        return -ENOMEM;
+                save->next = highmem_copy;
+                save->page = page;
+                save->data = (void *) get_zeroed_page(GFP_ATOMIC);
+                if (!save->data) {
+                        kfree(save);
+                        return -ENOMEM;
+                }
+                kaddr = kmap_atomic(page, KM_USER0);
+                memcpy(save->data, kaddr, PAGE_SIZE);
+                kunmap_atomic(kaddr, KM_USER0);
+                highmem_copy = save;
+        }
+        return 0;
+}
+#endif /* CONFIG_HIGHMEM */
+
+
+static int save_highmem(void)
+{
+#ifdef CONFIG_HIGHMEM
+        struct zone *zone;
+        int res = 0;
+
+        pr_debug("swsusp: Saving Highmem\n");
+        for_each_zone(zone) {
+                if (is_highmem(zone))
+                        res = save_highmem_zone(zone);
+                if (res)
+                        return res;
+        }
+#endif
+        return 0;
+}
+
+static int restore_highmem(void)
+{
+#ifdef CONFIG_HIGHMEM
+        printk("swsusp: Restoring Highmem\n");
+        while (highmem_copy) {
+                struct highmem_page *save = highmem_copy;
+                void *kaddr;
+                highmem_copy = save->next;
+
+                kaddr = kmap_atomic(save->page, KM_USER0);
+                memcpy(kaddr, save->data, PAGE_SIZE);
+                kunmap_atomic(kaddr, KM_USER0);
+                free_page((long) save->data);
+                kfree(save);
+        }
+#endif
+        return 0;
+}
+
+
+static int pfn_is_nosave(unsigned long pfn)
+{
+        unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
+        unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
+        return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}
+
+/**
+ *      saveable - Determine whether a page should be cloned or not.
+ *      @pfn:   The page
+ *
+ *      We save a page if it's Reserved, and not in the range of pages
+ *      statically defined as 'unsaveable', or if it isn't reserved, and
+ *      isn't part of a free chunk of pages.
+ */
+
+static int saveable(struct zone * zone, unsigned long * zone_pfn)
+{
+        unsigned long pfn = *zone_pfn + zone->zone_start_pfn;
+        struct page * page;
+
+        if (!pfn_valid(pfn))
+                return 0;
+
+        page = pfn_to_page(pfn);
+        BUG_ON(PageReserved(page) && PageNosave(page));
+        if (PageNosave(page))
+                return 0;
+        if (PageReserved(page) && pfn_is_nosave(pfn)) {
+                pr_debug("[nosave pfn 0x%lx]", pfn);
+                return 0;
+        }
+        if (PageNosaveFree(page))
+                return 0;
+
+        return 1;
+}
+
+static void count_data_pages(void)
+{
+        struct zone *zone;
+        unsigned long zone_pfn;
+
+        nr_copy_pages = 0;
+
+        for_each_zone(zone) {
+                if (is_highmem(zone))
+                        continue;
+                mark_free_pages(zone);
+                for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
+                        nr_copy_pages += saveable(zone, &zone_pfn);
+        }
+}
+
+
+static void copy_data_pages(void)
+{
+        struct zone *zone;
+        unsigned long zone_pfn;
+        struct pbe * pbe = pagedir_nosave;
+        
+        pr_debug("copy_data_pages(): pages to copy: %d\n", nr_copy_pages);
+        for_each_zone(zone) {
+                if (is_highmem(zone))
+                        continue;
+                mark_free_pages(zone);
+                for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
+                        if (saveable(zone, &zone_pfn)) {
+                                struct page * page;
+                                page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
+                                BUG_ON(!pbe);
+                                pbe->orig_address = (long) page_address(page);
+                                /* copy_page is not usable for copying task structs. */
+                                memcpy((void *)pbe->address, (void *)pbe->orig_address, PAGE_SIZE);
+                                pbe = pbe->next;
+                        }
+                }
+        }
+        BUG_ON(pbe);
+}
+
+
+/**
+ *      calc_nr - Determine the number of pages needed for a pbe list.
+ */
+
+static int calc_nr(int nr_copy)
+{
+        int extra = 0;
+        int mod = !!(nr_copy % PBES_PER_PAGE);
+        int diff = (nr_copy / PBES_PER_PAGE) + mod;
+
+        do {
+                extra += diff;
+                nr_copy += diff;
+                mod = !!(nr_copy % PBES_PER_PAGE);
+                diff = (nr_copy / PBES_PER_PAGE) + mod - extra;
+        } while (diff > 0);
+
+        return nr_copy;
+}
+
+/**
+ *      free_pagedir - free pages allocated with alloc_pagedir()
+ */
+
+static inline void free_pagedir(struct pbe *pblist)
+{
+        struct pbe *pbe;
+
+        while (pblist) {
+                pbe = (pblist + PB_PAGE_SKIP)->next;
+                free_page((unsigned long)pblist);
+                pblist = pbe;
+        }
+}
+
+/**
+ *      fill_pb_page - Create a list of PBEs on a given memory page
+ */
+
+static inline void fill_pb_page(struct pbe *pbpage)
+{
+        struct pbe *p;
+
+        p = pbpage;
+        pbpage += PB_PAGE_SKIP;
+        do
+                p->next = p + 1;
+        while (++p < pbpage);
+}
+
+/**
+ *      create_pbe_list - Create a list of PBEs on top of a given chain
+ *      of memory pages allocated with alloc_pagedir()
+ */
+
+static void create_pbe_list(struct pbe *pblist, unsigned nr_pages)
+{
+        struct pbe *pbpage, *p;
+        unsigned num = PBES_PER_PAGE;
+
+        for_each_pb_page (pbpage, pblist) {
+                if (num >= nr_pages)
+                        break;
+
+                fill_pb_page(pbpage);
+                num += PBES_PER_PAGE;
+        }
+        if (pbpage) {
+                for (num -= PBES_PER_PAGE - 1, p = pbpage; num < nr_pages; p++, num++)
+                        p->next = p + 1;
+                p->next = NULL;
+        }
+        pr_debug("create_pbe_list(): initialized %d PBEs\n", num);
+}
+
+/**
+ *      alloc_pagedir - Allocate the page directory.
+ *
+ *      First, determine exactly how many pages we need and
+ *      allocate them.
+ *
+ *      We arrange the pages in a chain: each page is an array of PBES_PER_PAGE
+ *      struct pbe elements (pbes) and the last element in the page points
+ *      to the next page.
+ *
+ *      On each page we set up a list of struct_pbe elements.
+ */
+
+static struct pbe * alloc_pagedir(unsigned nr_pages)
+{
+        unsigned num;
+        struct pbe *pblist, *pbe;
+
+        if (!nr_pages)
+                return NULL;
+
+        pr_debug("alloc_pagedir(): nr_pages = %d\n", nr_pages);
+        pblist = (struct pbe *)get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+        for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
+                        pbe = pbe->next, num += PBES_PER_PAGE) {
+                pbe += PB_PAGE_SKIP;
+                pbe->next = (struct pbe *)get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+        }
+        if (!pbe) { /* get_zeroed_page() failed */
+                free_pagedir(pblist);
+                pblist = NULL;
+        }
+        return pblist;
+}
+
+/**
+ *      free_image_pages - Free pages allocated for snapshot
+ */
+
+static void free_image_pages(void)
+{
+        struct pbe * p;
+
+        for_each_pbe(p, pagedir_save) {
+                if (p->address) {
+                        ClearPageNosave(virt_to_page(p->address));
+                        free_page(p->address);
+                        p->address = 0;
+                }
+        }
+}
+
+/**
+ *      alloc_image_pages - Allocate pages for the snapshot.
+ */
+
+static int alloc_image_pages(void)
+{
+        struct pbe * p;
+
+        for_each_pbe(p, pagedir_save) {
+                p->address = get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+                if (!p->address)
+                        return -ENOMEM;
+                SetPageNosave(virt_to_page(p->address));
+        }
+        return 0;
+}
+
+void swsusp_free(void)
+{
+        BUG_ON(PageNosave(virt_to_page(pagedir_save)));
+        BUG_ON(PageNosaveFree(virt_to_page(pagedir_save)));
+        free_image_pages();
+        free_pagedir(pagedir_save);
+}
+
+
+/**
+ *      enough_free_mem - Make sure we enough free memory to snapshot.
+ *
+ *      Returns TRUE or FALSE after checking the number of available 
+ *      free pages.
+ */
+
+static int enough_free_mem(void)
+{
+        if (nr_free_pages() < (nr_copy_pages + PAGES_FOR_IO)) {
+                pr_debug("swsusp: Not enough free pages: Have %d\n",
+                         nr_free_pages());
+                return 0;
+        }
+        return 1;
+}
+
+
+/**
+ *      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.
+ *
+ *      FIXME: si_swapinfo(&i) returns all swap devices information.
+ *      We should only consider resume_device. 
+ */
+
+static int enough_swap(void)
+{
+        struct sysinfo i;
+
+        si_swapinfo(&i);
+        if (i.freeswap < (nr_copy_pages + PAGES_FOR_IO))  {
+                pr_debug("swsusp: Not enough swap. Need %ld\n",i.freeswap);
+                return 0;
+        }
+        return 1;
+}
+
+static int swsusp_alloc(void)
+{
+        int error;
+
+        pr_debug("suspend: (pages needed: %d + %d free: %d)\n",
+                 nr_copy_pages, PAGES_FOR_IO, nr_free_pages());
+
+        pagedir_nosave = NULL;
+        if (!enough_free_mem())
+                return -ENOMEM;
+
+        if (!enough_swap())
+                return -ENOSPC;
+
+        nr_copy_pages = calc_nr(nr_copy_pages);
+
+        if (!(pagedir_save = alloc_pagedir(nr_copy_pages))) {
+                printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
+                return -ENOMEM;
+        }
+        create_pbe_list(pagedir_save, nr_copy_pages);
+        pagedir_nosave = pagedir_save;
+        if ((error = alloc_image_pages())) {
+                printk(KERN_ERR "suspend: Allocating image pages failed.\n");
+                swsusp_free();
+                return error;
+        }
+
+        nr_copy_pages_check = nr_copy_pages;
+        return 0;
+}
+
+static int suspend_prepare_image(void)
+{
+        int error;
+
+        pr_debug("swsusp: critical section: \n");
+        if (save_highmem()) {
+                printk(KERN_CRIT "Suspend machine: Not enough free pages for highmem\n");
+                restore_highmem();
+                return -ENOMEM;
+        }
+
+        drain_local_pages();
+        count_data_pages();
+        printk("swsusp: Need to copy %u pages\n", nr_copy_pages);
+
+        error = swsusp_alloc();
+        if (error)
+                return error;
+        
+        /* During allocating of suspend pagedir, new cold pages may appear. 
+         * Kill them.
+         */
+        drain_local_pages();
+        copy_data_pages();
+
+        /*
+         * End of critical section. From now on, we can write to memory,
+         * but we should not touch disk. This specially means we must _not_
+         * touch swap space! Except we must write out our image of course.
+         */
+
+        printk("swsusp: critical section/: done (%d pages copied)\n", nr_copy_pages );
+        return 0;
+}
+
+
+/* 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)
+{
+        int error;
+        device_resume();
+        lock_swapdevices();
+        error = write_suspend_image();
+        /* This will unlock ignored swap devices since writing is finished */
+        lock_swapdevices();
+        return error;
+
+}
+
+
+extern asmlinkage int swsusp_arch_suspend(void);
+extern asmlinkage int swsusp_arch_resume(void);
+
+
+asmlinkage int swsusp_save(void)
+{
+        int error = 0;
+
+        if ((error = swsusp_swap_check())) {
+                printk(KERN_ERR "swsusp: FATAL: cannot find swap device, try "
+                                "swapon -a!\n");
+                return error;
+        }
+        return suspend_prepare_image();
+}
+
+int swsusp_suspend(void)
+{
+        int error;
+        if ((error = arch_prepare_suspend()))
+                return error;
+        local_irq_disable();
+        /* At this point, device_suspend() has been called, but *not*
+         * device_power_down(). We *must* device_power_down() now.
+         * Otherwise, drivers for some devices (e.g. interrupt controllers)
+         * become desynchronized with the actual state of the hardware
+         * at resume time, and evil weirdness ensues.
+         */
+        if ((error = device_power_down(PMSG_FREEZE))) {
+                printk(KERN_ERR "Some devices failed to power down, aborting suspend\n");
+                local_irq_enable();
+                swsusp_free();
+                return error;
+        }
+        save_processor_state();
+        if ((error = swsusp_arch_suspend()))
+                swsusp_free();
+        /* Restore control flow magically appears here */
+        restore_processor_state();
+        BUG_ON (nr_copy_pages_check != nr_copy_pages);
+        restore_highmem();
+        device_power_up();
+        local_irq_enable();
+        return error;
+}
+
+int swsusp_resume(void)
+{
+        int error;
+        local_irq_disable();
+        if (device_power_down(PMSG_FREEZE))
+                printk(KERN_ERR "Some devices failed to power down, very bad\n");
+        /* We'll ignore saved state, but this gets preempt count (etc) right */
+        save_processor_state();
+        error = swsusp_arch_resume();
+        /* Code below is only ever reached in case of failure. Otherwise
+         * execution continues at place where swsusp_arch_suspend was called
+         */
+        BUG_ON(!error);
+        restore_processor_state();
+        restore_highmem();
+        device_power_up();
+        local_irq_enable();
+        return error;
+}
+
+/* More restore stuff */
+
+/*
+ * Returns true if given address/order collides with any orig_address 
+ */
+static int does_collide_order(unsigned long addr, int order)
+{
+        int i;
+        
+        for (i=0; i < (1<<order); i++)
+                if (!PageNosaveFree(virt_to_page(addr + i * PAGE_SIZE)))
+                        return 1;
+        return 0;
+}
+
+/**
+ *      On resume, for storing the PBE list and the image,
+ *      we can only use memory pages that do not conflict with the pages
+ *      which had been used before suspend.
+ *
+ *      We don't know which pages are usable until we allocate them.
+ *
+ *      Allocated but unusable (ie eaten) memory pages are linked together
+ *      to create a list, so that we can free them easily
+ *
+ *      We could have used a type other than (void *)
+ *      for this purpose, but ...
+ */
+static void **eaten_memory = NULL;
+
+static inline void eat_page(void *page)
+{
+        void **c;
+
+        c = eaten_memory;
+        eaten_memory = page;
+        *eaten_memory = c;
+}
+
+static unsigned long get_usable_page(unsigned gfp_mask)
+{
+        unsigned long m;
+
+        m = get_zeroed_page(gfp_mask);
+        while (does_collide_order(m, 0)) {
+                eat_page((void *)m);
+                m = get_zeroed_page(gfp_mask);
+                if (!m)
+                        break;
+        }
+        return m;
+}
+
+static void free_eaten_memory(void)
+{
+        unsigned long m;
+        void **c;
+        int i = 0;
+
+        c = eaten_memory;
+        while (c) {
+                m = (unsigned long)c;
+                c = *c;
+                free_page(m);
+                i++;
+        }
+        eaten_memory = NULL;
+        pr_debug("swsusp: %d unused pages freed\n", i);
+}
+
+/**
+ *      check_pagedir - We ensure here that pages that the PBEs point to
+ *      won't collide with pages where we're going to restore from the loaded
+ *      pages later
+ */
+
+static int check_pagedir(struct pbe *pblist)
+{
+        struct pbe *p;
+
+        /* This is necessary, so that we can free allocated pages
+         * in case of failure
+         */
+        for_each_pbe (p, pblist)
+                p->address = 0UL;
+
+        for_each_pbe (p, pblist) {
+                p->address = get_usable_page(GFP_ATOMIC);
+                if (!p->address)
+                        return -ENOMEM;
+        }
+        return 0;
+}
+
+/**
+ *      swsusp_pagedir_relocate - It is possible, that some memory pages
+ *      occupied by the list of PBEs collide with pages where we're going to
+ *      restore from the loaded pages later.  We relocate them here.
+ */
+
+static struct pbe * swsusp_pagedir_relocate(struct pbe *pblist)
+{
+        struct zone *zone;
+        unsigned long zone_pfn;
+        struct pbe *pbpage, *tail, *p;
+        void *m;
+        int rel = 0, error = 0;
+
+        if (!pblist) /* a sanity check */
+                return NULL;
+
+        pr_debug("swsusp: Relocating pagedir (%lu pages to check)\n",
+                        swsusp_info.pagedir_pages);
+
+        /* Set page flags */
+
+        for_each_zone(zone) {
+                for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
+                        SetPageNosaveFree(pfn_to_page(zone_pfn +
+                                        zone->zone_start_pfn));
+        }
+
+        /* Clear orig addresses */
+
+        for_each_pbe (p, pblist)
+                ClearPageNosaveFree(virt_to_page(p->orig_address));
+
+        tail = pblist + PB_PAGE_SKIP;
+
+        /* Relocate colliding pages */
+
+        for_each_pb_page (pbpage, pblist) {
+                if (does_collide_order((unsigned long)pbpage, 0)) {
+                        m = (void *)get_usable_page(GFP_ATOMIC | __GFP_COLD);
+                        if (!m) {
+                                error = -ENOMEM;
+                                break;
+                        }
+                        memcpy(m, (void *)pbpage, PAGE_SIZE);
+                        if (pbpage == pblist)
+                                pblist = (struct pbe *)m;
+                        else
+                                tail->next = (struct pbe *)m;
+
+                        eat_page((void *)pbpage);
+                        pbpage = (struct pbe *)m;
+
+                        /* We have to link the PBEs again */
+
+                        for (p = pbpage; p < pbpage + PB_PAGE_SKIP; p++)
+                                if (p->next) /* needed to save the end */
+                                        p->next = p + 1;
+
+                        rel++;
+                }
+                tail = pbpage + PB_PAGE_SKIP;
+        }
+
+        if (error) {
+                printk("\nswsusp: Out of memory\n\n");
+                free_pagedir(pblist);
+                free_eaten_memory();
+                pblist = NULL;
+        }
+        else
+                printk("swsusp: Relocated %d pages\n", rel);
+
+        return pblist;
+}
+
+/**
+ *      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_get(bio);
+        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;
+        }
+
+        if (rw == WRITE)
+                bio_set_pages_dirty(bio);
+
+        atomic_set(&io_done, 1);
+        submit_bio(rw | (1 << BIO_RW_SYNC), bio);
+        while (atomic_read(&io_done))
+                yield();
+
+ 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);
+}
+
+/*
+ * Sanity check if this image makes sense with this kernel/swap context
+ * I really don't think that it's foolproof but more than nothing..
+ */
+
+static const char * sanity_check(void)
+{
+        dump_info();
+        if(swsusp_info.version_code != LINUX_VERSION_CODE)
+                return "kernel version";
+        if(swsusp_info.num_physpages != num_physpages)
+                return "memory size";
+        if (strcmp(swsusp_info.uts.sysname,system_utsname.sysname))
+                return "system type";
+        if (strcmp(swsusp_info.uts.release,system_utsname.release))
+                return "kernel release";
+        if (strcmp(swsusp_info.uts.version,system_utsname.version))
+                return "version";
+        if (strcmp(swsusp_info.uts.machine,system_utsname.machine))
+                return "machine";
+        if(swsusp_info.cpus != num_online_cpus())
+                return "number of cpus";
+        return NULL;
+}
+
+
+static int check_header(void)
+{
+        const char * reason = NULL;
+        int error;
+
+        if ((error = bio_read_page(swp_offset(swsusp_header.swsusp_info), &swsusp_info)))
+                return error;
+
+        /* Is this same machine? */
+        if ((reason = sanity_check())) {
+                printk(KERN_ERR "swsusp: Resume mismatch: %s\n",reason);
+                return -EPERM;
+        }
+        nr_copy_pages = swsusp_info.image_pages;
+        return error;
+}
+
+static int check_sig(void)
+{
+        int error;
+
+        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 { 
+                printk(KERN_ERR "swsusp: Suspend partition has wrong signature?\n");
+                return -EINVAL;
+        }
+        if (!error)
+                pr_debug("swsusp: Signature found, resuming\n");
+        return error;
+}
+
+/**
+ *      data_read - Read image pages from swap.
+ *
+ *      You do not need to check for overlaps, check_pagedir()
+ *      already did that.
+ */
+
+static int data_read(struct pbe *pblist)
+{
+        struct pbe * p;
+        int error = 0;
+        int i = 0;
+        int mod = swsusp_info.image_pages / 100;
+
+        if (!mod)
+                mod = 1;
+
+        printk("swsusp: Reading image data (%lu pages):     ",
+                        swsusp_info.image_pages);
+
+        for_each_pbe (p, pblist) {
+                if (!(i % mod))
+                        printk("\b\b\b\b%3d%%", i / mod);
+
+                error = bio_read_page(swp_offset(p->swap_address),
+                                  (void *)p->address);
+                if (error)
+                        return error;
+
+                i++;
+        }
+        printk("\b\b\b\bdone\n");
+        return error;
+}
+
+extern dev_t name_to_dev_t(const char *line);
+
+/**
+ *      read_pagedir - Read page backup list pages from swap
+ */
+
+static int read_pagedir(struct pbe *pblist)
+{
+        struct pbe *pbpage, *p;
+        unsigned i = 0;
+        int error;
+
+        if (!pblist)
+                return -EFAULT;
+
+        printk("swsusp: Reading pagedir (%lu pages)\n",
+                        swsusp_info.pagedir_pages);
+
+        for_each_pb_page (pbpage, pblist) {
+                unsigned long offset = swp_offset(swsusp_info.pagedir[i++]);
+
+                error = -EFAULT;
+                if (offset) {
+                        p = (pbpage + PB_PAGE_SKIP)->next;
+                        error = bio_read_page(offset, (void *)pbpage);
+                        (pbpage + PB_PAGE_SKIP)->next = p;
+                }
+                if (error)
+                        break;
+        }
+
+        if (error)
+                free_page((unsigned long)pblist);
+
+        BUG_ON(i != swsusp_info.pagedir_pages);
+
+        return error;
+}
+
+
+static int check_suspend_image(void)
+{
+        int error = 0;
+
+        if ((error = check_sig()))
+                return error;
+
+        if ((error = check_header()))
+                return error;
+
+        return 0;
+}
+
+static int read_suspend_image(void)
+{
+        int error = 0;
+        struct pbe *p;
+
+        if (!(p = alloc_pagedir(nr_copy_pages)))
+                return -ENOMEM;
+
+        if ((error = read_pagedir(p)))
+                return error;
+
+        create_pbe_list(p, nr_copy_pages);
+
+        if (!(pagedir_nosave = swsusp_pagedir_relocate(p)))
+                return -ENOMEM;
+
+        /* Allocate memory for the image and read the data from swap */
+
+        error = check_pagedir(pagedir_nosave);
+        free_eaten_memory();
+        if (!error)
+                error = data_read(pagedir_nosave);
+
+        if (error) { /* We fail cleanly */
+                for_each_pbe (p, pagedir_nosave)
+                        if (p->address) {
+                                free_page(p->address);
+                                p->address = 0UL;
+                        }
+                free_pagedir(pagedir_nosave);
+        }
+        return error;
+}
+
+/**
+ *      swsusp_check - Check for saved image in swap
+ */
+
+int swsusp_check(void)
+{
+        int error;
+
+        if (!swsusp_resume_device) {
+                if (!strlen(resume_file))
+                        return -ENOENT;
+                swsusp_resume_device = name_to_dev_t(resume_file);
+                pr_debug("swsusp: Resume From Partition %s\n", resume_file);
+        } else {
+                pr_debug("swsusp: Resume From Partition %d:%d\n",
+                         MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
+        }
+
+        resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
+        if (!IS_ERR(resume_bdev)) {
+                set_blocksize(resume_bdev, PAGE_SIZE);
+                error = check_suspend_image();
+                if (error)
+                    blkdev_put(resume_bdev);
+        } else
+                error = PTR_ERR(resume_bdev);
+
+        if (!error)
+                pr_debug("swsusp: resume file found\n");
+        else
+                pr_debug("swsusp: Error %d check for resume file\n", error);
+        return error;
+}
+
+/**
+ *      swsusp_read - Read saved image from swap.
+ */
+
+int swsusp_read(void)
+{
+        int error;
+
+        if (IS_ERR(resume_bdev)) {
+                pr_debug("swsusp: block device not initialised\n");
+                return PTR_ERR(resume_bdev);
+        }
+
+        error = read_suspend_image();
+        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_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);
+}