Add TuxOnIce support

1 files changed, 1932 insertions, 0 deletions

diff --git a/kernel/power/tuxonice_io.c b/kernel/power/tuxonice_io.c
new file mode 100644
index 000000000..3c62c2682
--- /dev/null
+++ b/kernel/power/tuxonice_io.c
@@ -0,0 +1,1932 @@
+/*
+ * kernel/power/tuxonice_io.c
+ *
+ * Copyright (C) 1998-2001 Gabor Kuti <seasons@fornax.hu>
+ * Copyright (C) 1998,2001,2002 Pavel Machek <pavel@suse.cz>
+ * Copyright (C) 2002-2003 Florent Chabaud <fchabaud@free.fr>
+ * Copyright (C) 2002-2015 Nigel Cunningham (nigel at nigelcunningham com au)
+ *
+ * This file is released under the GPLv2.
+ *
+ * It contains high level IO routines for hibernating.
+ *
+ */
+
+#include <linux/suspend.h>
+#include <linux/version.h>
+#include <linux/utsname.h>
+#include <linux/mount.h>
+#include <linux/highmem.h>
+#include <linux/kthread.h>
+#include <linux/cpu.h>
+#include <linux/fs_struct.h>
+#include <linux/bio.h>
+#include <linux/fs_uuid.h>
+#include <linux/kmod.h>
+#include <asm/tlbflush.h>
+
+#include "tuxonice.h"
+#include "tuxonice_modules.h"
+#include "tuxonice_pageflags.h"
+#include "tuxonice_io.h"
+#include "tuxonice_ui.h"
+#include "tuxonice_storage.h"
+#include "tuxonice_prepare_image.h"
+#include "tuxonice_extent.h"
+#include "tuxonice_sysfs.h"
+#include "tuxonice_builtin.h"
+#include "tuxonice_checksum.h"
+#include "tuxonice_alloc.h"
+char alt_resume_param[256];
+
+/* Version read from image header at resume */
+static int toi_image_header_version;
+
+#define read_if_version(VERS, VAR, DESC, ERR_ACT) do {                                        \
+        if (likely(toi_image_header_version >= VERS))                                \
+                if (toiActiveAllocator->rw_header_chunk(READ, NULL,                \
+                                        (char *) &VAR, sizeof(VAR))) {                \
+                        abort_hibernate(TOI_FAILED_IO, "Failed to read DESC.");        \
+                        ERR_ACT;                                        \
+                }                                                                \
+} while(0)                                                                        \
+
+/* Variables shared between threads and updated under the mutex */
+static int io_write, io_finish_at, io_base, io_barmax, io_pageset, io_result;
+static int io_index, io_nextupdate, io_pc, io_pc_step;
+static DEFINE_MUTEX(io_mutex);
+static DEFINE_PER_CPU(struct page *, last_sought);
+static DEFINE_PER_CPU(struct page *, last_high_page);
+static DEFINE_PER_CPU(char *, checksum_locn);
+static DEFINE_PER_CPU(struct pbe *, last_low_page);
+static atomic_t io_count;
+atomic_t toi_io_workers;
+
+static int using_flusher;
+
+DECLARE_WAIT_QUEUE_HEAD(toi_io_queue_flusher);
+
+int toi_bio_queue_flusher_should_finish;
+
+int toi_max_workers;
+
+static char *image_version_error = "The image header version is newer than " \
+        "this kernel supports.";
+
+struct toi_module_ops *first_filter;
+
+static atomic_t toi_num_other_threads;
+static DECLARE_WAIT_QUEUE_HEAD(toi_worker_wait_queue);
+enum toi_worker_commands {
+        TOI_IO_WORKER_STOP,
+        TOI_IO_WORKER_RUN,
+        TOI_IO_WORKER_EXIT
+};
+static enum toi_worker_commands toi_worker_command;
+
+/**
+ * toi_attempt_to_parse_resume_device - determine if we can hibernate
+ *
+ * Can we hibernate, using the current resume= parameter?
+ **/
+int toi_attempt_to_parse_resume_device(int quiet)
+{
+        struct list_head *Allocator;
+        struct toi_module_ops *thisAllocator;
+        int result, returning = 0;
+
+        if (toi_activate_storage(0))
+                return 0;
+
+        toiActiveAllocator = NULL;
+        clear_toi_state(TOI_RESUME_DEVICE_OK);
+        clear_toi_state(TOI_CAN_RESUME);
+        clear_result_state(TOI_ABORTED);
+
+        if (!toiNumAllocators) {
+                if (!quiet)
+                        printk(KERN_INFO "TuxOnIce: No storage allocators have "
+                                "been registered. Hibernating will be "
+                                "disabled.\n");
+                goto cleanup;
+        }
+
+        list_for_each(Allocator, &toiAllocators) {
+                thisAllocator = list_entry(Allocator, struct toi_module_ops,
+                                                                type_list);
+
+                /*
+                 * Not sure why you'd want to disable an allocator, but
+                 * we should honour the flag if we're providing it
+                 */
+                if (!thisAllocator->enabled)
+                        continue;
+
+                result = thisAllocator->parse_sig_location(
+                                resume_file, (toiNumAllocators == 1),
+                                quiet);
+
+                switch (result) {
+                case -EINVAL:
+                        /* For this allocator, but not a valid
+                         * configuration. Error already printed. */
+                        goto cleanup;
+
+                case 0:
+                        /* For this allocator and valid. */
+                        toiActiveAllocator = thisAllocator;
+
+                        set_toi_state(TOI_RESUME_DEVICE_OK);
+                        set_toi_state(TOI_CAN_RESUME);
+                        returning = 1;
+                        goto cleanup;
+                }
+        }
+        if (!quiet)
+                printk(KERN_INFO "TuxOnIce: No matching enabled allocator "
+                                "found. Resuming disabled.\n");
+cleanup:
+        toi_deactivate_storage(0);
+        return returning;
+}
+
+void attempt_to_parse_resume_device2(void)
+{
+        toi_prepare_usm();
+        toi_attempt_to_parse_resume_device(0);
+        toi_cleanup_usm();
+}
+
+void save_restore_alt_param(int replace, int quiet)
+{
+        static char resume_param_save[255];
+        static unsigned long toi_state_save;
+
+        if (replace) {
+                toi_state_save = toi_state;
+                strcpy(resume_param_save, resume_file);
+                strcpy(resume_file, alt_resume_param);
+        } else {
+                strcpy(resume_file, resume_param_save);
+                toi_state = toi_state_save;
+        }
+        toi_attempt_to_parse_resume_device(quiet);
+}
+
+void attempt_to_parse_alt_resume_param(void)
+{
+        int ok = 0;
+
+        /* Temporarily set resume_param to the poweroff value */
+        if (!strlen(alt_resume_param))
+                return;
+
+        printk(KERN_INFO "=== Trying Poweroff Resume2 ===\n");
+        save_restore_alt_param(SAVE, NOQUIET);
+        if (test_toi_state(TOI_CAN_RESUME))
+                ok = 1;
+
+        printk(KERN_INFO "=== Done ===\n");
+        save_restore_alt_param(RESTORE, QUIET);
+
+        /* If not ok, clear the string */
+        if (ok)
+                return;
+
+        printk(KERN_INFO "Can't resume from that location; clearing "
+                        "alt_resume_param.\n");
+        alt_resume_param[0] = '\0';
+}
+
+/**
+ * noresume_reset_modules - reset data structures in case of non resuming
+ *
+ * When we read the start of an image, modules (and especially the
+ * active allocator) might need to reset data structures if we
+ * decide to remove the image rather than resuming from it.
+ **/
+static void noresume_reset_modules(void)
+{
+        struct toi_module_ops *this_filter;
+
+        list_for_each_entry(this_filter, &toi_filters, type_list)
+                if (this_filter->noresume_reset)
+                        this_filter->noresume_reset();
+
+        if (toiActiveAllocator && toiActiveAllocator->noresume_reset)
+                toiActiveAllocator->noresume_reset();
+}
+
+/**
+ * fill_toi_header - fill the hibernate header structure
+ * @struct toi_header: Header data structure to be filled.
+ **/
+static int fill_toi_header(struct toi_header *sh)
+{
+        int i, error;
+
+        error = init_header((struct swsusp_info *) sh);
+        if (error)
+                return error;
+
+        sh->pagedir = pagedir1;
+        sh->pageset_2_size = pagedir2.size;
+        sh->param0 = toi_result;
+        sh->param1 = toi_bkd.toi_action;
+        sh->param2 = toi_bkd.toi_debug_state;
+        sh->param3 = toi_bkd.toi_default_console_level;
+        sh->root_fs = current->fs->root.mnt->mnt_sb->s_dev;
+        for (i = 0; i < 4; i++)
+                sh->io_time[i/2][i%2] = toi_bkd.toi_io_time[i/2][i%2];
+        sh->bkd = boot_kernel_data_buffer;
+        return 0;
+}
+
+/**
+ * rw_init_modules - initialize modules
+ * @rw:                Whether we are reading of writing an image.
+ * @which:        Section of the image being processed.
+ *
+ * Iterate over modules, preparing the ones that will be used to read or write
+ * data.
+ **/
+static int rw_init_modules(int rw, int which)
+{
+        struct toi_module_ops *this_module;
+        /* Initialise page transformers */
+        list_for_each_entry(this_module, &toi_filters, type_list) {
+                if (!this_module->enabled)
+                        continue;
+                if (this_module->rw_init && this_module->rw_init(rw, which)) {
+                        abort_hibernate(TOI_FAILED_MODULE_INIT,
+                                "Failed to initialize the %s filter.",
+                                this_module->name);
+                        return 1;
+                }
+        }
+
+        /* Initialise allocator */
+        if (toiActiveAllocator->rw_init(rw, which)) {
+                abort_hibernate(TOI_FAILED_MODULE_INIT,
+                                "Failed to initialise the allocator.");
+                return 1;
+        }
+
+        /* Initialise other modules */
+        list_for_each_entry(this_module, &toi_modules, module_list) {
+                if (!this_module->enabled ||
+                    this_module->type == FILTER_MODULE ||
+                    this_module->type == WRITER_MODULE)
+                        continue;
+                if (this_module->rw_init && this_module->rw_init(rw, which)) {
+                        set_abort_result(TOI_FAILED_MODULE_INIT);
+                        printk(KERN_INFO "Setting aborted flag due to module "
+                                        "init failure.\n");
+                        return 1;
+                }
+        }
+
+        return 0;
+}
+
+/**
+ * rw_cleanup_modules - cleanup modules
+ * @rw:        Whether we are reading of writing an image.
+ *
+ * Cleanup components after reading or writing a set of pages.
+ * Only the allocator may fail.
+ **/
+static int rw_cleanup_modules(int rw)
+{
+        struct toi_module_ops *this_module;
+        int result = 0;
+
+        /* Cleanup other modules */
+        list_for_each_entry(this_module, &toi_modules, module_list) {
+                if (!this_module->enabled ||
+                    this_module->type == FILTER_MODULE ||
+                    this_module->type == WRITER_MODULE)
+                        continue;
+                if (this_module->rw_cleanup)
+                        result |= this_module->rw_cleanup(rw);
+        }
+
+        /* Flush data and cleanup */
+        list_for_each_entry(this_module, &toi_filters, type_list) {
+                if (!this_module->enabled)
+                        continue;
+                if (this_module->rw_cleanup)
+                        result |= this_module->rw_cleanup(rw);
+        }
+
+        result |= toiActiveAllocator->rw_cleanup(rw);
+
+        return result;
+}
+
+static struct page *copy_page_from_orig_page(struct page *orig_page, int is_high)
+{
+        int index, min, max;
+        struct page *high_page = NULL,
+                    **my_last_high_page = raw_cpu_ptr(&last_high_page),
+                    **my_last_sought = raw_cpu_ptr(&last_sought);
+        struct pbe *this, **my_last_low_page = raw_cpu_ptr(&last_low_page);
+        void *compare;
+
+        if (is_high) {
+                if (*my_last_sought && *my_last_high_page &&
+                                *my_last_sought < orig_page)
+                        high_page = *my_last_high_page;
+                else
+                        high_page = (struct page *) restore_highmem_pblist;
+                this = (struct pbe *) kmap(high_page);
+                compare = orig_page;
+        } else {
+                if (*my_last_sought && *my_last_low_page &&
+                                *my_last_sought < orig_page)
+                        this = *my_last_low_page;
+                else
+                        this = restore_pblist;
+                compare = page_address(orig_page);
+        }
+
+        *my_last_sought = orig_page;
+
+        /* Locate page containing pbe */
+        while (this[PBES_PER_PAGE - 1].next &&
+                        this[PBES_PER_PAGE - 1].orig_address < compare) {
+                if (is_high) {
+                        struct page *next_high_page = (struct page *)
+                                this[PBES_PER_PAGE - 1].next;
+                        kunmap(high_page);
+                        this = kmap(next_high_page);
+                        high_page = next_high_page;
+                } else
+                        this = this[PBES_PER_PAGE - 1].next;
+        }
+
+        /* Do a binary search within the page */
+        min = 0;
+        max = PBES_PER_PAGE;
+        index = PBES_PER_PAGE / 2;
+        while (max - min) {
+                if (!this[index].orig_address ||
+                    this[index].orig_address > compare)
+                        max = index;
+                else if (this[index].orig_address == compare) {
+                        if (is_high) {
+                                struct page *page = this[index].address;
+                                *my_last_high_page = high_page;
+                                kunmap(high_page);
+                                return page;
+                        }
+                        *my_last_low_page = this;
+                        return virt_to_page(this[index].address);
+                } else
+                        min = index;
+                index = ((max + min) / 2);
+        };
+
+        if (is_high)
+                kunmap(high_page);
+
+        abort_hibernate(TOI_FAILED_IO, "Failed to get destination page for"
+                " orig page %p. This[min].orig_address=%p.\n", orig_page,
+                this[index].orig_address);
+        return NULL;
+}
+
+/**
+ * write_next_page - write the next page in a pageset
+ * @data_pfn: The pfn where the next data to write is located.
+ * @my_io_index: The index of the page in the pageset.
+ * @write_pfn: The pfn number to write in the image (where the data belongs).
+ *
+ * Get the pfn of the next page to write, map the page if necessary and do the
+ * write.
+ **/
+static int write_next_page(unsigned long *data_pfn, int *my_io_index,
+                unsigned long *write_pfn)
+{
+        struct page *page;
+        char **my_checksum_locn = raw_cpu_ptr(&checksum_locn);
+        int result = 0, was_present;
+
+        *data_pfn = memory_bm_next_pfn(io_map, 0);
+
+        /* Another thread could have beaten us to it. */
+        if (*data_pfn == BM_END_OF_MAP) {
+                if (atomic_read(&io_count)) {
+                        printk(KERN_INFO "Ran out of pfns but io_count is "
+                                        "still %d.\n", atomic_read(&io_count));
+                        BUG();
+                }
+                mutex_unlock(&io_mutex);
+                return -ENODATA;
+        }
+
+        *my_io_index = io_finish_at - atomic_sub_return(1, &io_count);
+
+        memory_bm_clear_bit(io_map, 0, *data_pfn);
+        page = pfn_to_page(*data_pfn);
+
+        was_present = kernel_page_present(page);
+        if (!was_present)
+                kernel_map_pages(page, 1, 1);
+
+        if (io_pageset == 1)
+                *write_pfn = memory_bm_next_pfn(pageset1_map, 0);
+        else {
+                *write_pfn = *data_pfn;
+                *my_checksum_locn = tuxonice_get_next_checksum();
+        }
+
+        TOI_TRACE_DEBUG(*data_pfn, "_PS%d_write %d", io_pageset, *my_io_index);
+
+        mutex_unlock(&io_mutex);
+
+        if (io_pageset == 2 && tuxonice_calc_checksum(page, *my_checksum_locn))
+                return 1;
+
+        result = first_filter->write_page(*write_pfn, TOI_PAGE, page,
+                        PAGE_SIZE);
+
+        if (!was_present)
+                kernel_map_pages(page, 1, 0);
+
+        return result;
+}
+
+/**
+ * read_next_page - read the next page in a pageset
+ * @my_io_index: The index of the page in the pageset.
+ * @write_pfn: The pfn in which the data belongs.
+ *
+ * Read a page of the image into our buffer. It can happen (here and in the
+ * write routine) that threads don't get run until after other CPUs have done
+ * all the work. This was the cause of the long standing issue with
+ * occasionally getting -ENODATA errors at the end of reading the image. We
+ * therefore need to check there's actually a page to read before trying to
+ * retrieve one.
+ **/
+
+static int read_next_page(int *my_io_index, unsigned long *write_pfn,
+                struct page *buffer)
+{
+        unsigned int buf_size = PAGE_SIZE;
+        unsigned long left = atomic_read(&io_count);
+
+        if (!left)
+                return -ENODATA;
+
+        /* Start off assuming the page we read isn't resaved */
+        *my_io_index = io_finish_at - atomic_sub_return(1, &io_count);
+
+        mutex_unlock(&io_mutex);
+
+        /*
+         * Are we aborting? If so, don't submit any more I/O as
+         * resetting the resume_attempted flag (from ui.c) will
+         * clear the bdev flags, making this thread oops.
+         */
+        if (unlikely(test_toi_state(TOI_STOP_RESUME))) {
+                atomic_dec(&toi_io_workers);
+                if (!atomic_read(&toi_io_workers)) {
+                        /*
+                         * So we can be sure we'll have memory for
+                         * marking that we haven't resumed.
+                         */
+                        rw_cleanup_modules(READ);
+                        set_toi_state(TOI_IO_STOPPED);
+                }
+                while (1)
+                        schedule();
+        }
+
+        /*
+         * See toi_bio_read_page in tuxonice_bio.c:
+         * read the next page in the image.
+         */
+        return first_filter->read_page(write_pfn, TOI_PAGE, buffer, &buf_size);
+}
+
+static void use_read_page(unsigned long write_pfn, struct page *buffer)
+{
+        struct page *final_page = pfn_to_page(write_pfn),
+                    *copy_page = final_page;
+        char *virt, *buffer_virt;
+        int was_present, cpu = smp_processor_id();
+        unsigned long idx = 0;
+
+        if (io_pageset == 1 && (!pageset1_copy_map ||
+                        !memory_bm_test_bit(pageset1_copy_map, cpu, write_pfn))) {
+                int is_high = PageHighMem(final_page);
+                copy_page = copy_page_from_orig_page(is_high ? (void *) write_pfn : final_page, is_high);
+        }
+
+        if (!memory_bm_test_bit(io_map, cpu, write_pfn)) {
+                int test = !memory_bm_test_bit(io_map, cpu, write_pfn);
+                toi_message(TOI_IO, TOI_VERBOSE, 0, "Discard %ld (%d).", write_pfn, test);
+                mutex_lock(&io_mutex);
+                idx = atomic_add_return(1, &io_count);
+                mutex_unlock(&io_mutex);
+                return;
+        }
+
+        virt = kmap(copy_page);
+        buffer_virt = kmap(buffer);
+        was_present = kernel_page_present(copy_page);
+        if (!was_present)
+                kernel_map_pages(copy_page, 1, 1);
+        memcpy(virt, buffer_virt, PAGE_SIZE);
+        if (!was_present)
+                kernel_map_pages(copy_page, 1, 0);
+        kunmap(copy_page);
+        kunmap(buffer);
+        memory_bm_clear_bit(io_map, cpu, write_pfn);
+        TOI_TRACE_DEBUG(write_pfn, "_PS%d_read", io_pageset);
+}
+
+static unsigned long status_update(int writing, unsigned long done,
+                unsigned long ticks)
+{
+        int cs_index = writing ? 0 : 1;
+        unsigned long ticks_so_far = toi_bkd.toi_io_time[cs_index][1] + ticks;
+        unsigned long msec = jiffies_to_msecs(abs(ticks_so_far));
+        unsigned long pgs_per_s, estimate = 0, pages_left;
+
+        if (msec) {
+                pages_left = io_barmax - done;
+                pgs_per_s = 1000 * done / msec;
+                if (pgs_per_s)
+                        estimate = DIV_ROUND_UP(pages_left, pgs_per_s);
+        }
+
+        if (estimate && ticks > HZ / 2)
+                return toi_update_status(done, io_barmax,
+                        " %d/%d MB (%lu sec left)",
+                        MB(done+1), MB(io_barmax), estimate);
+
+        return toi_update_status(done, io_barmax, " %d/%d MB",
+                MB(done+1), MB(io_barmax));
+}
+
+/**
+ * worker_rw_loop - main loop to read/write pages
+ *
+ * The main I/O loop for reading or writing pages. The io_map bitmap is used to
+ * track the pages to read/write.
+ * If we are reading, the pages are loaded to their final (mapped) pfn.
+ * Data is non zero iff this is a thread started via start_other_threads.
+ * In that case, we stay in here until told to quit.
+ **/
+static int worker_rw_loop(void *data)
+{
+        unsigned long data_pfn, write_pfn, next_jiffies = jiffies + HZ / 4,
+                      jif_index = 1, start_time = jiffies, thread_num;
+        int result = 0, my_io_index = 0, last_worker;
+        struct page *buffer = toi_alloc_page(28, TOI_ATOMIC_GFP);
+        cpumask_var_t orig_mask;
+
+        if (!alloc_cpumask_var(&orig_mask, GFP_KERNEL)) {
+                printk(KERN_EMERG "Failed to allocate cpumask for TuxOnIce I/O thread %ld.\n", (unsigned long) data);
+                result = -ENOMEM;
+                goto out;
+        }
+
+        cpumask_copy(orig_mask, tsk_cpus_allowed(current));
+
+        current->flags |= PF_NOFREEZE;
+
+top:
+        mutex_lock(&io_mutex);
+        thread_num = atomic_read(&toi_io_workers);
+
+        cpumask_copy(tsk_cpus_allowed(current), orig_mask);
+        schedule();
+
+        atomic_inc(&toi_io_workers);
+
+        while (atomic_read(&io_count) >= atomic_read(&toi_io_workers) &&
+                !(io_write && test_result_state(TOI_ABORTED)) &&
+                toi_worker_command == TOI_IO_WORKER_RUN) {
+                if (!thread_num && jiffies > next_jiffies) {
+                        next_jiffies += HZ / 4;
+                        if (toiActiveAllocator->update_throughput_throttle)
+                                toiActiveAllocator->update_throughput_throttle(
+                                                jif_index);
+                        jif_index++;
+                }
+
+                /*
+                 * What page to use? If reading, don't know yet which page's
+                 * data will be read, so always use the buffer. If writing,
+                 * use the copy (Pageset1) or original page (Pageset2), but
+                 * always write the pfn of the original page.
+                 */
+                if (io_write)
+                        result = write_next_page(&data_pfn, &my_io_index,
+                                        &write_pfn);
+                else /* Reading */
+                        result = read_next_page(&my_io_index, &write_pfn,
+                                        buffer);
+
+                if (result) {
+                        mutex_lock(&io_mutex);
+                        /* Nothing to do? */
+                        if (result == -ENODATA) {
+                                toi_message(TOI_IO, TOI_VERBOSE, 0,
+                                        "Thread %d has no more work.",
+                                        smp_processor_id());
+                                break;
+                        }
+
+                        io_result = result;
+
+                        if (io_write) {
+                                printk(KERN_INFO "Write chunk returned %d.\n",
+                                                result);
+                                abort_hibernate(TOI_FAILED_IO,
+                                        "Failed to write a chunk of the "
+                                        "image.");
+                                break;
+                        }
+
+                        if (io_pageset == 1) {
+                                printk(KERN_ERR "\nBreaking out of I/O loop "
+                                        "because of result code %d.\n", result);
+                                break;
+                        }
+                        panic("Read chunk returned (%d)", result);
+                }
+
+                /*
+                 * Discard reads of resaved pages while reading ps2
+                 * and unwanted pages while rereading ps2 when aborting.
+                 */
+                if (!io_write) {
+                        if (!PageResave(pfn_to_page(write_pfn)))
+                                use_read_page(write_pfn, buffer);
+                        else {
+                                mutex_lock(&io_mutex);
+                                toi_message(TOI_IO, TOI_VERBOSE, 0,
+                                                "Resaved %ld.", write_pfn);
+                                atomic_inc(&io_count);
+                                mutex_unlock(&io_mutex);
+                        }
+                }
+
+                if (!thread_num) {
+                        if(my_io_index + io_base > io_nextupdate)
+                                io_nextupdate = status_update(io_write,
+                                                my_io_index + io_base,
+                                                jiffies - start_time);
+
+                        if (my_io_index > io_pc) {
+                                printk(KERN_CONT "...%d%%", 20 * io_pc_step);
+                                io_pc_step++;
+                                io_pc = io_finish_at * io_pc_step / 5;
+                        }
+                }
+
+                toi_cond_pause(0, NULL);
+
+                /*
+                 * Subtle: If there's less I/O still to be done than threads
+                 * running, quit. This stops us doing I/O beyond the end of
+                 * the image when reading.
+                 *
+                 * Possible race condition. Two threads could do the test at
+                 * the same time; one should exit and one should continue.
+                 * Therefore we take the mutex before comparing and exiting.
+                 */
+
+                mutex_lock(&io_mutex);
+        }
+
+        last_worker = atomic_dec_and_test(&toi_io_workers);
+        toi_message(TOI_IO, TOI_VERBOSE, 0, "%d workers left.", atomic_read(&toi_io_workers));
+        mutex_unlock(&io_mutex);
+
+        if ((unsigned long) data && toi_worker_command != TOI_IO_WORKER_EXIT) {
+                /* Were we the last thread and we're using a flusher thread? */
+                if (last_worker && using_flusher) {
+                        toiActiveAllocator->finish_all_io();
+                }
+                /* First, if we're doing I/O, wait for it to finish */
+                wait_event(toi_worker_wait_queue, toi_worker_command != TOI_IO_WORKER_RUN);
+                /* Then wait to be told what to do next */
+                wait_event(toi_worker_wait_queue, toi_worker_command != TOI_IO_WORKER_STOP);
+                if (toi_worker_command == TOI_IO_WORKER_RUN)
+                        goto top;
+        }
+
+        if (thread_num)
+                atomic_dec(&toi_num_other_threads);
+
+out:
+        toi_message(TOI_IO, TOI_LOW, 0, "Thread %d exiting.", thread_num);
+        toi__free_page(28, buffer);
+        free_cpumask_var(orig_mask);
+
+        return result;
+}
+
+int toi_start_other_threads(void)
+{
+        int cpu;
+        struct task_struct *p;
+        int to_start = (toi_max_workers ? toi_max_workers : num_online_cpus()) - 1;
+  unsigned long num_started = 0;
+
+        if (test_action_state(TOI_NO_MULTITHREADED_IO))
+                return 0;
+
+        toi_worker_command = TOI_IO_WORKER_STOP;
+
+        for_each_online_cpu(cpu) {
+                if (num_started == to_start)
+                        break;
+
+                if (cpu == smp_processor_id())
+                        continue;
+
+                p = kthread_create_on_node(worker_rw_loop, (void *) num_started + 1,
+                                cpu_to_node(cpu), "ktoi_io/%d", cpu);
+                if (IS_ERR(p)) {
+                        printk(KERN_ERR "ktoi_io for %i failed\n", cpu);
+                        continue;
+                }
+                kthread_bind(p, cpu);
+                p->flags |= PF_MEMALLOC;
+                wake_up_process(p);
+                num_started++;
+                atomic_inc(&toi_num_other_threads);
+        }
+
+        toi_message(TOI_IO, TOI_LOW, 0, "Started %d threads.", num_started);
+        return num_started;
+}
+
+void toi_stop_other_threads(void)
+{
+        toi_message(TOI_IO, TOI_LOW, 0, "Stopping other threads.");
+        toi_worker_command = TOI_IO_WORKER_EXIT;
+        wake_up(&toi_worker_wait_queue);
+}
+
+/**
+ * do_rw_loop - main highlevel function for reading or writing pages
+ *
+ * Create the io_map bitmap and call worker_rw_loop to perform I/O operations.
+ **/
+static int do_rw_loop(int write, int finish_at, struct memory_bitmap *pageflags,
+                int base, int barmax, int pageset)
+{
+        int index = 0, cpu, result = 0, workers_started;
+        unsigned long pfn, next;
+
+        first_filter = toi_get_next_filter(NULL);
+
+        if (!finish_at)
+                return 0;
+
+        io_write = write;
+        io_finish_at = finish_at;
+        io_base = base;
+        io_barmax = barmax;
+        io_pageset = pageset;
+        io_index = 0;
+        io_pc = io_finish_at / 5;
+        io_pc_step = 1;
+        io_result = 0;
+        io_nextupdate = base + 1;
+        toi_bio_queue_flusher_should_finish = 0;
+
+        for_each_online_cpu(cpu) {
+                per_cpu(last_sought, cpu) = NULL;
+                per_cpu(last_low_page, cpu) = NULL;
+                per_cpu(last_high_page, cpu) = NULL;
+        }
+
+        /* Ensure all bits clear */
+        memory_bm_clear(io_map);
+
+        memory_bm_position_reset(io_map);
+        next = memory_bm_next_pfn(io_map, 0);
+
+        BUG_ON(next != BM_END_OF_MAP);
+
+        /* Set the bits for the pages to write */
+        memory_bm_position_reset(pageflags);
+
+        pfn = memory_bm_next_pfn(pageflags, 0);
+        toi_trace_index++;
+
+        while (pfn != BM_END_OF_MAP && index < finish_at) {
+                TOI_TRACE_DEBUG(pfn, "_io_pageset_%d (%d/%d)", pageset, index + 1, finish_at);
+                memory_bm_set_bit(io_map, 0, pfn);
+                pfn = memory_bm_next_pfn(pageflags, 0);
+                index++;
+        }
+
+        BUG_ON(next != BM_END_OF_MAP || index < finish_at);
+
+        memory_bm_position_reset(io_map);
+        toi_trace_index++;
+
+        atomic_set(&io_count, finish_at);
+
+        memory_bm_position_reset(pageset1_map);
+
+        mutex_lock(&io_mutex);
+
+        clear_toi_state(TOI_IO_STOPPED);
+
+        using_flusher = (atomic_read(&toi_num_other_threads) &&
+                         toiActiveAllocator->io_flusher &&
+                         !test_action_state(TOI_NO_FLUSHER_THREAD));
+
+        workers_started = atomic_read(&toi_num_other_threads);
+
+        memory_bm_position_reset(io_map);
+        memory_bm_position_reset(pageset1_copy_map);
+
+        toi_worker_command = TOI_IO_WORKER_RUN;
+        wake_up(&toi_worker_wait_queue);
+
+        mutex_unlock(&io_mutex);
+
+        if (using_flusher)
+                result = toiActiveAllocator->io_flusher(write);
+        else
+                worker_rw_loop(NULL);
+
+        while (atomic_read(&toi_io_workers))
+                schedule();
+
+        printk(KERN_CONT "\n");
+
+        toi_worker_command = TOI_IO_WORKER_STOP;
+        wake_up(&toi_worker_wait_queue);
+
+        if (unlikely(test_toi_state(TOI_STOP_RESUME))) {
+                if (!atomic_read(&toi_io_workers)) {
+                        rw_cleanup_modules(READ);
+                        set_toi_state(TOI_IO_STOPPED);
+                }
+                while (1)
+                        schedule();
+        }
+        set_toi_state(TOI_IO_STOPPED);
+
+        if (!io_result && !result && !test_result_state(TOI_ABORTED)) {
+                unsigned long next;
+
+                toi_update_status(io_base + io_finish_at, io_barmax,
+                                " %d/%d MB ",
+                                MB(io_base + io_finish_at), MB(io_barmax));
+
+                memory_bm_position_reset(io_map);
+                next = memory_bm_next_pfn(io_map, 0);
+                if  (next != BM_END_OF_MAP) {
+                        printk(KERN_INFO "Finished I/O loop but still work to "
+                                        "do?\nFinish at = %d. io_count = %d.\n",
+                                        finish_at, atomic_read(&io_count));
+                        printk(KERN_INFO "I/O bitmap still records work to do."
+                                        "%ld.\n", next);
+                        BUG();
+                        do {
+                                cpu_relax();
+                        } while (0);
+                }
+        }
+
+        return io_result ? io_result : result;
+}
+
+/**
+ * write_pageset - write a pageset to disk.
+ * @pagedir:        Which pagedir to write.
+ *
+ * Returns:
+ *        Zero on success or -1 on failure.
+ **/
+int write_pageset(struct pagedir *pagedir)
+{
+        int finish_at, base = 0;
+        int barmax = pagedir1.size + pagedir2.size;
+        long error = 0;
+        struct memory_bitmap *pageflags;
+        unsigned long start_time, end_time;
+
+        /*
+         * Even if there is nothing to read or write, the allocator
+         * may need the init/cleanup for it's housekeeping.  (eg:
+         * Pageset1 may start where pageset2 ends when writing).
+         */
+        finish_at = pagedir->size;
+
+        if (pagedir->id == 1) {
+                toi_prepare_status(DONT_CLEAR_BAR,
+                                "Writing kernel & process data...");
+                base = pagedir2.size;
+                if (test_action_state(TOI_TEST_FILTER_SPEED) ||
+                    test_action_state(TOI_TEST_BIO))
+                        pageflags = pageset1_map;
+                else
+                        pageflags = pageset1_copy_map;
+        } else {
+                toi_prepare_status(DONT_CLEAR_BAR, "Writing caches...");
+                pageflags = pageset2_map;
+        }
+
+        start_time = jiffies;
+
+        if (rw_init_modules(WRITE, pagedir->id)) {
+                abort_hibernate(TOI_FAILED_MODULE_INIT,
+                                "Failed to initialise modules for writing.");
+                error = 1;
+        }
+
+        if (!error)
+                error = do_rw_loop(WRITE, finish_at, pageflags, base, barmax,
+                                pagedir->id);
+
+        if (rw_cleanup_modules(WRITE) && !error) {
+                abort_hibernate(TOI_FAILED_MODULE_CLEANUP,
+                                "Failed to cleanup after writing.");
+                error = 1;
+        }
+
+        end_time = jiffies;
+
+        if ((end_time - start_time) && (!test_result_state(TOI_ABORTED))) {
+                toi_bkd.toi_io_time[0][0] += finish_at,
+                toi_bkd.toi_io_time[0][1] += (end_time - start_time);
+        }
+
+        return error;
+}
+
+/**
+ * read_pageset - highlevel function to read a pageset from disk
+ * @pagedir:                        pageset to read
+ * @overwrittenpagesonly:        Whether to read the whole pageset or
+ *                                only part of it.
+ *
+ * Returns:
+ *        Zero on success or -1 on failure.
+ **/
+static int read_pageset(struct pagedir *pagedir, int overwrittenpagesonly)
+{
+        int result = 0, base = 0;
+        int finish_at = pagedir->size;
+        int barmax = pagedir1.size + pagedir2.size;
+        struct memory_bitmap *pageflags;
+        unsigned long start_time, end_time;
+
+        if (pagedir->id == 1) {
+                toi_prepare_status(DONT_CLEAR_BAR,
+                                "Reading kernel & process data...");
+                pageflags = pageset1_map;
+        } else {
+                toi_prepare_status(DONT_CLEAR_BAR, "Reading caches...");
+                if (overwrittenpagesonly) {
+                        barmax = min(pagedir1.size, pagedir2.size);
+                        finish_at = min(pagedir1.size, pagedir2.size);
+                } else
+                        base = pagedir1.size;
+                pageflags = pageset2_map;
+        }
+
+        start_time = jiffies;
+
+        if (rw_init_modules(READ, pagedir->id)) {
+                toiActiveAllocator->remove_image();
+                result = 1;
+        } else
+                result = do_rw_loop(READ, finish_at, pageflags, base, barmax,
+                                pagedir->id);
+
+        if (rw_cleanup_modules(READ) && !result) {
+                abort_hibernate(TOI_FAILED_MODULE_CLEANUP,
+                                "Failed to cleanup after reading.");
+                result = 1;
+        }
+
+        /* Statistics */
+        end_time = jiffies;
+
+        if ((end_time - start_time) && (!test_result_state(TOI_ABORTED))) {
+                toi_bkd.toi_io_time[1][0] += finish_at,
+                toi_bkd.toi_io_time[1][1] += (end_time - start_time);
+        }
+
+        return result;
+}
+
+/**
+ * write_module_configs - store the modules configuration
+ *
+ * The configuration for each module is stored in the image header.
+ * Returns: Int
+ *        Zero on success, Error value otherwise.
+ **/
+static int write_module_configs(void)
+{
+        struct toi_module_ops *this_module;
+        char *buffer = (char *) toi_get_zeroed_page(22, TOI_ATOMIC_GFP);
+        int len, index = 1;
+        struct toi_module_header toi_module_header;
+
+        if (!buffer) {
+                printk(KERN_INFO "Failed to allocate a buffer for saving "
+                                "module configuration info.\n");
+                return -ENOMEM;
+        }
+
+        /*
+         * We have to know which data goes with which module, so we at
+         * least write a length of zero for a module. Note that we are
+         * also assuming every module's config data takes <= PAGE_SIZE.
+         */
+
+        /* For each module (in registration order) */
+        list_for_each_entry(this_module, &toi_modules, module_list) {
+                if (!this_module->enabled || !this_module->storage_needed ||
+                    (this_module->type == WRITER_MODULE &&
+                     toiActiveAllocator != this_module))
+                        continue;
+
+                /* Get the data from the module */
+                len = 0;
+                if (this_module->save_config_info)
+                        len = this_module->save_config_info(buffer);
+
+                /* Save the details of the module */
+                toi_module_header.enabled = this_module->enabled;
+                toi_module_header.type = this_module->type;
+                toi_module_header.index = index++;
+                strncpy(toi_module_header.name, this_module->name,
+                                        sizeof(toi_module_header.name));
+                toiActiveAllocator->rw_header_chunk(WRITE,
+                                this_module,
+                                (char *) &toi_module_header,
+                                sizeof(toi_module_header));
+
+                /* Save the size of the data and any data returned */
+                toiActiveAllocator->rw_header_chunk(WRITE,
+                                this_module,
+                                (char *) &len, sizeof(int));
+                if (len)
+                        toiActiveAllocator->rw_header_chunk(
+                                WRITE, this_module, buffer, len);
+        }
+
+        /* Write a blank header to terminate the list */
+        toi_module_header.name[0] = '\0';
+        toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                        (char *) &toi_module_header, sizeof(toi_module_header));
+
+        toi_free_page(22, (unsigned long) buffer);
+        return 0;
+}
+
+/**
+ * read_one_module_config - read and configure one module
+ *
+ * Read the configuration for one module, and configure the module
+ * to match if it is loaded.
+ *
+ * Returns: Int
+ *        Zero on success, Error value otherwise.
+ **/
+static int read_one_module_config(struct toi_module_header *header)
+{
+        struct toi_module_ops *this_module;
+        int result, len;
+        char *buffer;
+
+        /* Find the module */
+        this_module = toi_find_module_given_name(header->name);
+
+        if (!this_module) {
+                if (header->enabled) {
+                        toi_early_boot_message(1, TOI_CONTINUE_REQ,
+                                "It looks like we need module %s for reading "
+                                "the image but it hasn't been registered.\n",
+                                header->name);
+                        if (!(test_toi_state(TOI_CONTINUE_REQ)))
+                                return -EINVAL;
+                } else
+                        printk(KERN_INFO "Module %s configuration data found, "
+                                "but the module hasn't registered. Looks like "
+                                "it was disabled, so we're ignoring its data.",
+                                header->name);
+        }
+
+        /* Get the length of the data (if any) */
+        result = toiActiveAllocator->rw_header_chunk(READ, NULL, (char *) &len,
+                        sizeof(int));
+        if (result) {
+                printk(KERN_ERR "Failed to read the length of the module %s's"
+                                " configuration data.\n",
+                                header->name);
+                return -EINVAL;
+        }
+
+        /* Read any data and pass to the module (if we found one) */
+        if (!len)
+                return 0;
+
+        buffer = (char *) toi_get_zeroed_page(23, TOI_ATOMIC_GFP);
+
+        if (!buffer) {
+                printk(KERN_ERR "Failed to allocate a buffer for reloading "
+                                "module configuration info.\n");
+                return -ENOMEM;
+        }
+
+        toiActiveAllocator->rw_header_chunk(READ, NULL, buffer, len);
+
+        if (!this_module)
+                goto out;
+
+        if (!this_module->save_config_info)
+                printk(KERN_ERR "Huh? Module %s appears to have a "
+                                "save_config_info, but not a load_config_info "
+                                "function!\n", this_module->name);
+        else
+                this_module->load_config_info(buffer, len);
+
+        /*
+         * Now move this module to the tail of its lists. This will put it in
+         * order. Any new modules will end up at the top of the lists. They
+         * should have been set to disabled when loaded (people will
+         * normally not edit an initrd to load a new module and then hibernate
+         * without using it!).
+         */
+
+        toi_move_module_tail(this_module);
+
+        this_module->enabled = header->enabled;
+
+out:
+        toi_free_page(23, (unsigned long) buffer);
+        return 0;
+}
+
+/**
+ * read_module_configs - reload module configurations from the image header.
+ *
+ * Returns: Int
+ *        Zero on success or an error code.
+ **/
+static int read_module_configs(void)
+{
+        int result = 0;
+        struct toi_module_header toi_module_header;
+        struct toi_module_ops *this_module;
+
+        /* All modules are initially disabled. That way, if we have a module
+         * loaded now that wasn't loaded when we hibernated, it won't be used
+         * in trying to read the data.
+         */
+        list_for_each_entry(this_module, &toi_modules, module_list)
+                this_module->enabled = 0;
+
+        /* Get the first module header */
+        result = toiActiveAllocator->rw_header_chunk(READ, NULL,
+                        (char *) &toi_module_header,
+                        sizeof(toi_module_header));
+        if (result) {
+                printk(KERN_ERR "Failed to read the next module header.\n");
+                return -EINVAL;
+        }
+
+        /* For each module (in registration order) */
+        while (toi_module_header.name[0]) {
+                result = read_one_module_config(&toi_module_header);
+
+                if (result)
+                        return -EINVAL;
+
+                /* Get the next module header */
+                result = toiActiveAllocator->rw_header_chunk(READ, NULL,
+                                (char *) &toi_module_header,
+                                sizeof(toi_module_header));
+
+                if (result) {
+                        printk(KERN_ERR "Failed to read the next module "
+                                        "header.\n");
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
+static inline int save_fs_info(struct fs_info *fs, struct block_device *bdev)
+{
+        return (!fs || IS_ERR(fs) || !fs->last_mount_size) ? 0 : 1;
+}
+
+int fs_info_space_needed(void)
+{
+        const struct super_block *sb;
+        int result = sizeof(int);
+
+        list_for_each_entry(sb, &super_blocks, s_list) {
+                struct fs_info *fs;
+
+                if (!sb->s_bdev)
+                        continue;
+
+                fs = fs_info_from_block_dev(sb->s_bdev);
+                if (save_fs_info(fs, sb->s_bdev))
+                        result += 16 + sizeof(dev_t) + sizeof(int) +
+                                fs->last_mount_size;
+                free_fs_info(fs);
+        }
+        return result;
+}
+
+static int fs_info_num_to_save(void)
+{
+        const struct super_block *sb;
+        int to_save = 0;
+
+        list_for_each_entry(sb, &super_blocks, s_list) {
+                struct fs_info *fs;
+
+                if (!sb->s_bdev)
+                        continue;
+
+                fs = fs_info_from_block_dev(sb->s_bdev);
+                if (save_fs_info(fs, sb->s_bdev))
+                        to_save++;
+                free_fs_info(fs);
+        }
+
+        return to_save;
+}
+
+static int fs_info_save(void)
+{
+        const struct super_block *sb;
+        int to_save = fs_info_num_to_save();
+
+        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL, (char *) &to_save,
+                                sizeof(int))) {
+                abort_hibernate(TOI_FAILED_IO, "Failed to write num fs_info"
+                                " to save.");
+                return -EIO;
+        }
+
+        list_for_each_entry(sb, &super_blocks, s_list) {
+                struct fs_info *fs;
+
+                if (!sb->s_bdev)
+                        continue;
+
+                fs = fs_info_from_block_dev(sb->s_bdev);
+                if (save_fs_info(fs, sb->s_bdev)) {
+                        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                                        &fs->uuid[0], 16)) {
+                                abort_hibernate(TOI_FAILED_IO, "Failed to "
+                                                "write uuid.");
+                                return -EIO;
+                        }
+                        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                                        (char *) &fs->dev_t, sizeof(dev_t))) {
+                                abort_hibernate(TOI_FAILED_IO, "Failed to "
+                                                "write dev_t.");
+                                return -EIO;
+                        }
+                        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                                        (char *) &fs->last_mount_size, sizeof(int))) {
+                                abort_hibernate(TOI_FAILED_IO, "Failed to "
+                                                "write last mount length.");
+                                return -EIO;
+                        }
+                        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                                        fs->last_mount, fs->last_mount_size)) {
+                                abort_hibernate(TOI_FAILED_IO, "Failed to "
+                                                "write uuid.");
+                                return -EIO;
+                        }
+                }
+                free_fs_info(fs);
+        }
+        return 0;
+}
+
+static int fs_info_load_and_check_one(void)
+{
+        char uuid[16], *last_mount;
+        int result = 0, ln;
+        dev_t dev_t;
+        struct block_device *dev;
+        struct fs_info *fs_info, seek;
+
+        if (toiActiveAllocator->rw_header_chunk(READ, NULL, uuid, 16)) {
+                abort_hibernate(TOI_FAILED_IO, "Failed to read uuid.");
+                return -EIO;
+        }
+
+        read_if_version(3, dev_t, "uuid dev_t field", return -EIO);
+
+        if (toiActiveAllocator->rw_header_chunk(READ, NULL, (char *) &ln,
+                                sizeof(int))) {
+                abort_hibernate(TOI_FAILED_IO,
+                                "Failed to read last mount size.");
+                return -EIO;
+        }
+
+        last_mount = kzalloc(ln, GFP_KERNEL);
+
+        if (!last_mount)
+                return -ENOMEM;
+
+        if (toiActiveAllocator->rw_header_chunk(READ, NULL, last_mount,        ln)) {
+                abort_hibernate(TOI_FAILED_IO,
+                                "Failed to read last mount timestamp.");
+                result = -EIO;
+                goto out_lmt;
+        }
+
+        strncpy((char *) &seek.uuid, uuid, 16);
+        seek.dev_t = dev_t;
+        seek.last_mount_size = ln;
+        seek.last_mount = last_mount;
+        dev_t = blk_lookup_fs_info(&seek);
+        if (!dev_t)
+                goto out_lmt;
+
+        dev = toi_open_by_devnum(dev_t);
+
+        fs_info = fs_info_from_block_dev(dev);
+        if (fs_info && !IS_ERR(fs_info)) {
+                if (ln != fs_info->last_mount_size) {
+                        printk(KERN_EMERG "Found matching uuid but last mount "
+                                        "time lengths differ?! "
+                                        "(%d vs %d).\n", ln,
+                                        fs_info->last_mount_size);
+                        result = -EINVAL;
+                } else {
+                        char buf[BDEVNAME_SIZE];
+                        result = !!memcmp(fs_info->last_mount, last_mount, ln);
+                        if (result)
+                                printk(KERN_EMERG "Last mount time for %s has "
+                                        "changed!\n", bdevname(dev, buf));
+                }
+        }
+        toi_close_bdev(dev);
+        free_fs_info(fs_info);
+out_lmt:
+        kfree(last_mount);
+        return result;
+}
+
+static int fs_info_load_and_check(void)
+{
+        int to_do, result = 0;
+
+        if (toiActiveAllocator->rw_header_chunk(READ, NULL, (char *) &to_do,
+                                sizeof(int))) {
+                abort_hibernate(TOI_FAILED_IO, "Failed to read num fs_info "
+                                "to load.");
+                return -EIO;
+        }
+
+        while(to_do--)
+                result |= fs_info_load_and_check_one();
+
+        return result;
+}
+
+/**
+ * write_image_header - write the image header after write the image proper
+ *
+ * Returns: Int
+ *        Zero on success, error value otherwise.
+ **/
+int write_image_header(void)
+{
+        int ret;
+        int total = pagedir1.size + pagedir2.size+2;
+        char *header_buffer = NULL;
+
+        /* Now prepare to write the header */
+        ret = toiActiveAllocator->write_header_init();
+        if (ret) {
+                abort_hibernate(TOI_FAILED_MODULE_INIT,
+                                "Active allocator's write_header_init"
+                                " function failed.");
+                goto write_image_header_abort;
+        }
+
+        /* Get a buffer */
+        header_buffer = (char *) toi_get_zeroed_page(24, TOI_ATOMIC_GFP);
+        if (!header_buffer) {
+                abort_hibernate(TOI_OUT_OF_MEMORY,
+                        "Out of memory when trying to get page for header!");
+                goto write_image_header_abort;
+        }
+
+        /* Write hibernate header */
+        if (fill_toi_header((struct toi_header *) header_buffer)) {
+                abort_hibernate(TOI_OUT_OF_MEMORY,
+                        "Failure to fill header information!");
+                goto write_image_header_abort;
+        }
+
+        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                        header_buffer, sizeof(struct toi_header))) {
+                abort_hibernate(TOI_OUT_OF_MEMORY,
+                        "Failure to write header info.");
+                goto write_image_header_abort;
+        }
+
+        if (toiActiveAllocator->rw_header_chunk(WRITE, NULL,
+                        (char *) &toi_max_workers, sizeof(toi_max_workers))) {
+                abort_hibernate(TOI_OUT_OF_MEMORY,
+                        "Failure to number of workers to use.");
+                goto write_image_header_abort;
+        }
+
+        /* Write filesystem info */
+        if (fs_info_save())
+                goto write_image_header_abort;
+
+        /* Write module configurations */
+        ret = write_module_configs();
+        if (ret) {
+                abort_hibernate(TOI_FAILED_IO,
+                                "Failed to write module configs.");
+                goto write_image_header_abort;
+        }
+
+        if (memory_bm_write(pageset1_map,
+                                toiActiveAllocator->rw_header_chunk)) {
+                abort_hibernate(TOI_FAILED_IO,
+                                "Failed to write bitmaps.");
+                goto write_image_header_abort;
+        }
+
+        /* Flush data and let allocator cleanup */
+        if (toiActiveAllocator->write_header_cleanup()) {
+                abort_hibernate(TOI_FAILED_IO,
+                                "Failed to cleanup writing header.");
+                goto write_image_header_abort_no_cleanup;
+        }
+
+        if (test_result_state(TOI_ABORTED))
+                goto write_image_header_abort_no_cleanup;
+
+        toi_update_status(total, total, NULL);
+
+out:
+        if (header_buffer)
+                toi_free_page(24, (unsigned long) header_buffer);
+        return ret;
+
+write_image_header_abort:
+        toiActiveAllocator->write_header_cleanup();
+write_image_header_abort_no_cleanup:
+        ret = -1;
+        goto out;
+}
+
+/**
+ * sanity_check - check the header
+ * @sh:        the header which was saved at hibernate time.
+ *
+ * Perform a few checks, seeking to ensure that the kernel being
+ * booted matches the one hibernated. They need to match so we can
+ * be _sure_ things will work. It is not absolutely impossible for
+ * resuming from a different kernel to work, just not assured.
+ **/
+static char *sanity_check(struct toi_header *sh)
+{
+        char *reason = check_image_kernel((struct swsusp_info *) sh);
+
+        if (reason)
+                return reason;
+
+        if (!test_action_state(TOI_IGNORE_ROOTFS)) {
+                const struct super_block *sb;
+                list_for_each_entry(sb, &super_blocks, s_list) {
+                        if ((!(sb->s_flags & MS_RDONLY)) &&
+                            (sb->s_type->fs_flags & FS_REQUIRES_DEV))
+                                return "Device backed fs has been mounted "
+                                        "rw prior to resume or initrd/ramfs "
+                                        "is mounted rw.";
+                }
+        }
+
+        return NULL;
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(freeze_wait);
+
+#define FREEZE_IN_PROGRESS (~0)
+
+static int freeze_result;
+
+static void do_freeze(struct work_struct *dummy)
+{
+        freeze_result = freeze_processes();
+        wake_up(&freeze_wait);
+        trap_non_toi_io = 1;
+}
+
+static DECLARE_WORK(freeze_work, do_freeze);
+
+/**
+ * __read_pageset1 - test for the existence of an image and attempt to load it
+ *
+ * Returns:        Int
+ *        Zero if image found and pageset1 successfully loaded.
+ *        Error if no image found or loaded.
+ **/
+static int __read_pageset1(void)
+{
+        int i, result = 0;
+        char *header_buffer = (char *) toi_get_zeroed_page(25, TOI_ATOMIC_GFP),
+             *sanity_error = NULL;
+        struct toi_header *toi_header;
+
+        if (!header_buffer) {
+                printk(KERN_INFO "Unable to allocate a page for reading the "
+                                "signature.\n");
+                return -ENOMEM;
+        }
+
+        /* Check for an image */
+        result = toiActiveAllocator->image_exists(1);
+        if (result == 3) {
+                result = -ENODATA;
+                toi_early_boot_message(1, 0, "The signature from an older "
+                                "version of TuxOnIce has been detected.");
+                goto out_remove_image;
+        }
+
+        if (result != 1) {
+                result = -ENODATA;
+                noresume_reset_modules();
+                printk(KERN_INFO "TuxOnIce: No image found.\n");
+                goto out;
+        }
+
+        /*
+         * Prepare the active allocator for reading the image header. The
+         * activate allocator might read its own configuration.
+         *
+         * NB: This call may never return because there might be a signature
+         * for a different image such that we warn the user and they choose
+         * to reboot. (If the device ids look erroneous (2.4 vs 2.6) or the
+         * location of the image might be unavailable if it was stored on a
+         * network connection).
+         */
+
+        result = toiActiveAllocator->read_header_init();
+        if (result) {
+                printk(KERN_INFO "TuxOnIce: Failed to initialise, reading the "
+                                "image header.\n");
+                goto out_remove_image;
+        }
+
+        /* Check for noresume command line option */
+        if (test_toi_state(TOI_NORESUME_SPECIFIED)) {
+                printk(KERN_INFO "TuxOnIce: Noresume on command line. Removed "
+                                "image.\n");
+                goto out_remove_image;
+        }
+
+        /* Check whether we've resumed before */
+        if (test_toi_state(TOI_RESUMED_BEFORE)) {
+                toi_early_boot_message(1, 0, NULL);
+                if (!(test_toi_state(TOI_CONTINUE_REQ))) {
+                        printk(KERN_INFO "TuxOnIce: Tried to resume before: "
+                                        "Invalidated image.\n");
+                        goto out_remove_image;
+                }
+        }
+
+        clear_toi_state(TOI_CONTINUE_REQ);
+
+        toi_image_header_version = toiActiveAllocator->get_header_version();
+
+        if (unlikely(toi_image_header_version > TOI_HEADER_VERSION)) {
+                toi_early_boot_message(1, 0, image_version_error);
+                if (!(test_toi_state(TOI_CONTINUE_REQ))) {
+                        printk(KERN_INFO "TuxOnIce: Header version too new: "
+                                        "Invalidated image.\n");
+                        goto out_remove_image;
+                }
+        }
+
+        /* Read hibernate header */
+        result = toiActiveAllocator->rw_header_chunk(READ, NULL,
+                        header_buffer, sizeof(struct toi_header));
+        if (result < 0) {
+                printk(KERN_ERR "TuxOnIce: Failed to read the image "
+                                "signature.\n");
+                goto out_remove_image;
+        }
+
+        toi_header = (struct toi_header *) header_buffer;
+
+        /*
+         * NB: This call may also result in a reboot rather than returning.
+         */
+
+        sanity_error = sanity_check(toi_header);
+        if (sanity_error) {
+                toi_early_boot_message(1, TOI_CONTINUE_REQ,
+                                sanity_error);
+                printk(KERN_INFO "TuxOnIce: Sanity check failed.\n");
+                goto out_remove_image;
+        }
+
+        /*
+         * We have an image and it looks like it will load okay.
+         *
+         * Get metadata from header. Don't override commandline parameters.
+         *
+         * We don't need to save the image size limit because it's not used
+         * during resume and will be restored with the image anyway.
+         */
+
+        memcpy((char *) &pagedir1,
+                (char *) &toi_header->pagedir, sizeof(pagedir1));
+        toi_result = toi_header->param0;
+        if (!toi_bkd.toi_debug_state) {
+                toi_bkd.toi_action =
+                        (toi_header->param1 & ~toi_bootflags_mask) |
+                        (toi_bkd.toi_action & toi_bootflags_mask);
+                toi_bkd.toi_debug_state = toi_header->param2;
+                toi_bkd.toi_default_console_level = toi_header->param3;
+        }
+        clear_toi_state(TOI_IGNORE_LOGLEVEL);
+        pagedir2.size = toi_header->pageset_2_size;
+        for (i = 0; i < 4; i++)
+                toi_bkd.toi_io_time[i/2][i%2] =
+                        toi_header->io_time[i/2][i%2];
+
+        set_toi_state(TOI_BOOT_KERNEL);
+        boot_kernel_data_buffer = toi_header->bkd;
+
+        read_if_version(1, toi_max_workers, "TuxOnIce max workers",
+                        goto out_remove_image);
+
+        /* Read filesystem info */
+        if (fs_info_load_and_check()) {
+                printk(KERN_EMERG "TuxOnIce: File system mount time checks "
+                        "failed. Refusing to corrupt your filesystems!\n");
+                goto out_remove_image;
+        }
+
+        /* Read module configurations */
+        result = read_module_configs();
+        if (result) {
+                pagedir1.size = 0;
+                pagedir2.size = 0;
+                printk(KERN_INFO "TuxOnIce: Failed to read TuxOnIce module "
+                                "configurations.\n");
+                clear_action_state(TOI_KEEP_IMAGE);
+                goto out_remove_image;
+        }
+
+        toi_prepare_console();
+
+        set_toi_state(TOI_NOW_RESUMING);
+
+        result = pm_notifier_call_chain(PM_RESTORE_PREPARE);
+        if (result)
+                goto out_notifier_call_chain;;
+
+        if (usermodehelper_disable())
+                goto out_enable_usermodehelper;
+
+        current->flags |= PF_NOFREEZE;
+        freeze_result = FREEZE_IN_PROGRESS;
+
+        schedule_work_on(cpumask_first(cpu_online_mask), &freeze_work);
+
+        toi_cond_pause(1, "About to read original pageset1 locations.");
+
+        /*
+         * See _toi_rw_header_chunk in tuxonice_bio.c:
+         * Initialize pageset1_map by reading the map from the image.
+         */
+        if (memory_bm_read(pageset1_map, toiActiveAllocator->rw_header_chunk))
+                goto out_thaw;
+
+        /*
+         * See toi_rw_cleanup in tuxonice_bio.c:
+         * Clean up after reading the header.
+         */
+        result = toiActiveAllocator->read_header_cleanup();
+        if (result) {
+                printk(KERN_ERR "TuxOnIce: Failed to cleanup after reading the "
+                                "image header.\n");
+                goto out_thaw;
+        }
+
+        toi_cond_pause(1, "About to read pagedir.");
+
+        /*
+         * Get the addresses of pages into which we will load the kernel to
+         * be copied back and check if they conflict with the ones we are using.
+         */
+        if (toi_get_pageset1_load_addresses()) {
+                printk(KERN_INFO "TuxOnIce: Failed to get load addresses for "
+                                "pageset1.\n");
+                goto out_thaw;
+        }
+
+        /* Read the original kernel back */
+        toi_cond_pause(1, "About to read pageset 1.");
+
+        /* Given the pagemap, read back the data from disk */
+        if (read_pageset(&pagedir1, 0)) {
+                toi_prepare_status(DONT_CLEAR_BAR, "Failed to read pageset 1.");
+                result = -EIO;
+                goto out_thaw;
+        }
+
+        toi_cond_pause(1, "About to restore original kernel.");
+        result = 0;
+
+        if (!toi_keeping_image &&
+            toiActiveAllocator->mark_resume_attempted)
+                toiActiveAllocator->mark_resume_attempted(1);
+
+        wait_event(freeze_wait, freeze_result != FREEZE_IN_PROGRESS);
+out:
+        current->flags &= ~PF_NOFREEZE;
+        toi_free_page(25, (unsigned long) header_buffer);
+        return result;
+
+out_thaw:
+        wait_event(freeze_wait, freeze_result != FREEZE_IN_PROGRESS);
+        trap_non_toi_io = 0;
+        thaw_processes();
+out_enable_usermodehelper:
+        usermodehelper_enable();
+out_notifier_call_chain:
+        pm_notifier_call_chain(PM_POST_RESTORE);
+        toi_cleanup_console();
+out_remove_image:
+        result = -EINVAL;
+        if (!toi_keeping_image)
+                toiActiveAllocator->remove_image();
+        toiActiveAllocator->read_header_cleanup();
+        noresume_reset_modules();
+        goto out;
+}
+
+/**
+ * read_pageset1 - highlevel function to read the saved pages
+ *
+ * Attempt to read the header and pageset1 of a hibernate image.
+ * Handle the outcome, complaining where appropriate.
+ **/
+int read_pageset1(void)
+{
+        int error;
+
+        error = __read_pageset1();
+
+        if (error && error != -ENODATA && error != -EINVAL &&
+                                        !test_result_state(TOI_ABORTED))
+                abort_hibernate(TOI_IMAGE_ERROR,
+                        "TuxOnIce: Error %d resuming\n", error);
+
+        return error;
+}
+
+/**
+ * get_have_image_data - check the image header
+ **/
+static char *get_have_image_data(void)
+{
+        char *output_buffer = (char *) toi_get_zeroed_page(26, TOI_ATOMIC_GFP);
+        struct toi_header *toi_header;
+
+        if (!output_buffer) {
+                printk(KERN_INFO "Output buffer null.\n");
+                return NULL;
+        }
+
+        /* Check for an image */
+        if (!toiActiveAllocator->image_exists(1) ||
+            toiActiveAllocator->read_header_init() ||
+            toiActiveAllocator->rw_header_chunk(READ, NULL,
+                        output_buffer, sizeof(struct toi_header))) {
+                sprintf(output_buffer, "0\n");
+                /*
+                 * From an initrd/ramfs, catting have_image and
+                 * getting a result of 0 is sufficient.
+                 */
+                clear_toi_state(TOI_BOOT_TIME);
+                goto out;
+        }
+
+        toi_header = (struct toi_header *) output_buffer;
+
+        sprintf(output_buffer, "1\n%s\n%s\n",
+                        toi_header->uts.machine,
+                        toi_header->uts.version);
+
+        /* Check whether we've resumed before */
+        if (test_toi_state(TOI_RESUMED_BEFORE))
+                strcat(output_buffer, "Resumed before.\n");
+
+out:
+        noresume_reset_modules();
+        return output_buffer;
+}
+
+/**
+ * read_pageset2 - read second part of the image
+ * @overwrittenpagesonly:        Read only pages which would have been
+ *                                verwritten by pageset1?
+ *
+ * Read in part or all of pageset2 of an image, depending upon
+ * whether we are hibernating and have only overwritten a portion
+ * with pageset1 pages, or are resuming and need to read them
+ * all.
+ *
+ * Returns: Int
+ *        Zero if no error, otherwise the error value.
+ **/
+int read_pageset2(int overwrittenpagesonly)
+{
+        int result = 0;
+
+        if (!pagedir2.size)
+                return 0;
+
+        result = read_pageset(&pagedir2, overwrittenpagesonly);
+
+        toi_cond_pause(1, "Pagedir 2 read.");
+
+        return result;
+}
+
+/**
+ * image_exists_read - has an image been found?
+ * @page:        Output buffer
+ *
+ * Store 0 or 1 in page, depending on whether an image is found.
+ * Incoming buffer is PAGE_SIZE and result is guaranteed
+ * to be far less than that, so we don't worry about
+ * overflow.
+ **/
+int image_exists_read(const char *page, int count)
+{
+        int len = 0;
+        char *result;
+
+        if (toi_activate_storage(0))
+                return count;
+
+        if (!test_toi_state(TOI_RESUME_DEVICE_OK))
+                toi_attempt_to_parse_resume_device(0);
+
+        if (!toiActiveAllocator) {
+                len = sprintf((char *) page, "-1\n");
+        } else {
+                result = get_have_image_data();
+                if (result) {
+                        len = sprintf((char *) page, "%s",  result);
+                        toi_free_page(26, (unsigned long) result);
+                }
+        }
+
+        toi_deactivate_storage(0);
+
+        return len;
+}
+
+/**
+ * image_exists_write - invalidate an image if one exists
+ **/
+int image_exists_write(const char *buffer, int count)
+{
+        if (toi_activate_storage(0))
+                return count;
+
+        if (toiActiveAllocator && toiActiveAllocator->image_exists(1))
+                toiActiveAllocator->remove_image();
+
+        toi_deactivate_storage(0);
+
+        clear_result_state(TOI_KEPT_IMAGE);
+
+        return count;
+}