[PATCH 14/19] TuxOnIce: Swap support.

[Nigel Cunningham]

Support for writing an image to swap. Unlike swsusp - and, I think,
uswsusp - this code supports multiple swap devices, striped swap and
compcache (it ignores compcache storage). Any combination of swap
partitions and swap files can be used.

Signed-off-by: Nigel Cunningham <nigel@xxxxxxxxxxxx>
---
 kernel/power/Kconfig         |    8 +
 kernel/power/Makefile        |    1 +
 kernel/power/tuxonice_swap.c | 1319 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1328 insertions(+), 0 deletions(-)
 create mode 100644 kernel/power/tuxonice_swap.c

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 51d57d4..d8e62b6 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -201,6 +201,14 @@ menuconfig TOI_CORE
 		  simple file. This should be possible, but we're still
 		  testing it.
 
+	config TOI_SWAP
+		bool "Swap Allocator"
+		depends on TOI_CORE && SWAP
+		default y
+		---help---
+		  This option enables support for storing an image in your
+		  swap space.
+
 	comment "General Options"
 		depends on TOI_CORE
 
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 41daada..9f6d06f 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -17,6 +17,7 @@ endif
 obj-$(CONFIG_TOI_CORE)		+= tuxonice_core.o
 obj-$(CONFIG_TOI_CRYPTO)	+= tuxonice_compress.o
 
+obj-$(CONFIG_TOI_SWAP)		+= tuxonice_block_io.o tuxonice_swap.o
 obj-$(CONFIG_TOI_FILE)		+= tuxonice_block_io.o tuxonice_file.o
 
 obj-$(CONFIG_PM)		+= main.o
diff --git a/kernel/power/tuxonice_swap.c b/kernel/power/tuxonice_swap.c
new file mode 100644
index 0000000..420edec
--- /dev/null
+++ b/kernel/power/tuxonice_swap.c
@@ -0,0 +1,1319 @@
+/*
+ * kernel/power/tuxonice_swap.c
+ *
+ * Copyright (C) 2004-2008 Nigel Cunningham (nigel at tuxonice net)
+ *
+ * Distributed under GPLv2.
+ *
+ * This file encapsulates functions for usage of swap space as a
+ * backing store.
+ */
+
+#include <linux/suspend.h>
+#include <linux/blkdev.h>
+#include <linux/swapops.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+
+#include "tuxonice.h"
+#include "tuxonice_sysfs.h"
+#include "tuxonice_modules.h"
+#include "tuxonice_io.h"
+#include "tuxonice_ui.h"
+#include "tuxonice_extent.h"
+#include "tuxonice_block_io.h"
+#include "tuxonice_alloc.h"
+#include "tuxonice_builtin.h"
+
+static struct toi_module_ops toi_swapops;
+
+/* --- Struct of pages stored on disk */
+
+struct sig_data {
+	dev_t device;
+	unsigned long sector;
+	int resume_attempted;
+	int orig_sig_type;
+};
+
+union diskpage {
+	union swap_header swh;	/* swh.magic is the only member used */
+	struct sig_data sig_data;
+};
+
+union p_diskpage {
+	union diskpage *pointer;
+	char *ptr;
+	unsigned long address;
+};
+
+enum {
+	IMAGE_SIGNATURE,
+	NO_IMAGE_SIGNATURE,
+	TRIED_RESUME,
+	NO_TRIED_RESUME,
+};
+
+/*
+ * Both of these point to versions of the swap header page. original_sig points
+ * to the data we read from disk at the start of hibernating or checking whether
+ * to resume. no_image is the page stored in the image header, showing what the
+ * swap header page looked like at the start of hibernating.
+ */
+static char *current_signature_page;
+static char no_image_signature_contents[sizeof(struct sig_data)];
+
+/* Devices used for swap */
+static struct toi_bdev_info devinfo[MAX_SWAPFILES];
+
+/* Extent chains for swap & blocks */
+static struct hibernate_extent_chain swapextents;
+static struct hibernate_extent_chain block_chain[MAX_SWAPFILES];
+
+static dev_t header_dev_t;
+static struct block_device *header_block_device;
+static unsigned long headerblock;
+
+/* For swapfile automatically swapon/off'd. */
+static char swapfilename[32] = "";
+static int toi_swapon_status;
+
+/* Header Page Information */
+static long header_pages_reserved;
+
+/* Swap Pages */
+static long swap_pages_allocated;
+
+/* User Specified Parameters. */
+
+static unsigned long resume_firstblock;
+static dev_t resume_swap_dev_t;
+static struct block_device *resume_block_device;
+
+static struct sysinfo swapinfo;
+
+/* Block devices open. */
+struct bdev_opened {
+	dev_t device;
+	struct block_device *bdev;
+};
+
+/*
+ * Entry MAX_SWAPFILES is the resume block device, which may
+ * be a swap device not enabled when we hibernate.
+ * Entry MAX_SWAPFILES + 1 is the header block device, which
+ * is needed before we find out which slot it occupies.
+ *
+ * We use a separate struct to devInfo so that we can track
+ * the bdevs we open, because if we need to abort resuming
+ * prior to the atomic restore, they need to be closed, but
+ * closing them after sucessfully resuming would be wrong.
+ */
+static struct bdev_opened *bdevs_opened[MAX_SWAPFILES + 2];
+
+/**
+ * close_bdev: Close a swap bdev.
+ *
+ * int: The swap entry number to close.
+ */
+static void close_bdev(int i)
+{
+	struct bdev_opened *this = bdevs_opened[i];
+
+	if (!this)
+		return;
+
+	blkdev_put(this->bdev, FMODE_READ | FMODE_NDELAY);
+	toi_kfree(8, this, sizeof(*this));
+	bdevs_opened[i] = NULL;
+}
+
+/**
+ * close_bdevs: Close all bdevs we opened.
+ *
+ * Close all bdevs that we opened and reset the related vars.
+ */
+static void close_bdevs(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_SWAPFILES + 2; i++)
+		close_bdev(i);
+
+	resume_block_device = NULL;
+	header_block_device = NULL;
+}
+
+/**
+ * open_bdev: Open a bdev at resume time.
+ *
+ * index: The swap index. May be MAX_SWAPFILES for the resume_dev_t
+ * (the user can have resume= pointing at a swap partition/file that isn't
+ * swapon'd when they hibernate. MAX_SWAPFILES+1 for the first page of the
+ * header. It will be from a swap partition that was enabled when we hibernated,
+ * but we don't know it's real index until we read that first page.
+ * dev_t: The device major/minor.
+ * display_errs: Whether to try to do this quietly.
+ *
+ * We stored a dev_t in the image header. Open the matching device without
+ * requiring /dev/<whatever> in most cases and record the details needed
+ * to close it later and avoid duplicating work.
+ */
+static struct block_device *open_bdev(int index, dev_t device, int display_errs)
+{
+	struct bdev_opened *this;
+	struct block_device *bdev;
+
+	if (bdevs_opened[index]) {
+		if (bdevs_opened[index]->device == device)
+			return bdevs_opened[index]->bdev;
+
+		close_bdev(index);
+	}
+
+	bdev = toi_open_by_devnum(device, FMODE_READ | FMODE_NDELAY);
+
+	if (IS_ERR(bdev) || !bdev) {
+		if (display_errs)
+			toi_early_boot_message(1, TOI_CONTINUE_REQ,
+				"Failed to get access to block device "
+				"\"%x\" (error %d).\n Maybe you need "
+				"to run mknod and/or lvmsetup in an "
+				"initrd/ramfs?", device, bdev);
+		return ERR_PTR(-EINVAL);
+	}
+
+	this = toi_kzalloc(8, sizeof(struct bdev_opened), GFP_KERNEL);
+	if (!this) {
+		printk(KERN_WARNING "TuxOnIce: Failed to allocate memory for "
+				"opening a bdev.");
+		blkdev_put(bdev, FMODE_READ | FMODE_NDELAY);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	bdevs_opened[index] = this;
+	this->device = device;
+	this->bdev = bdev;
+
+	return bdev;
+}
+
+/**
+ * enable_swapfile: Swapon the user specified swapfile prior to hibernating.
+ *
+ * Activate the given swapfile if it wasn't already enabled. Remember whether
+ * we really did swapon it for swapoffing later.
+ */
+static void enable_swapfile(void)
+{
+	int activateswapresult = -EINVAL;
+
+	if (swapfilename[0]) {
+		/* Attempt to swap on with maximum priority */
+		activateswapresult = sys_swapon(swapfilename, 0xFFFF);
+		if (activateswapresult && activateswapresult != -EBUSY)
+			printk("TuxOnIce: The swapfile/partition specified by "
+				"/sys/power/tuxonice/swap/swapfile "
+				"(%s) could not be turned on (error %d). "
+				"Attempting to continue.\n",
+				swapfilename, activateswapresult);
+		if (!activateswapresult)
+			toi_swapon_status = 1;
+	}
+}
+
+/**
+ * disable_swapfile: Swapoff any file swaponed at the start of the cycle.
+ *
+ * If we did successfully swapon a file at the start of the cycle, swapoff
+ * it now (finishing up).
+ */
+static void disable_swapfile(void)
+{
+	if (!toi_swapon_status)
+		return;
+
+	sys_swapoff(swapfilename);
+	toi_swapon_status = 0;
+}
+
+/**
+ * try_to_parse_resume_device: Try to parse resume=
+ *
+ * Any "swap:" has been stripped away and we just have the path to deal with.
+ * We attempt to do name_to_dev_t, open and stat the file. Having opened the
+ * file, get the struct block_device * to match.
+ */
+static int try_to_parse_resume_device(char *commandline, int quiet)
+{
+	struct kstat stat;
+	int error = 0;
+
+	wait_for_device_probe();
+	resume_swap_dev_t = name_to_dev_t(commandline);
+
+	if (!resume_swap_dev_t) {
+		struct file *file = filp_open(commandline,
+				O_RDONLY|O_LARGEFILE, 0);
+
+		if (!IS_ERR(file) && file) {
+			vfs_getattr(file->f_vfsmnt, file->f_dentry, &stat);
+			filp_close(file, NULL);
+		} else
+			error = vfs_stat(commandline, &stat);
+		if (!error)
+			resume_swap_dev_t = stat.rdev;
+	}
+
+	if (!resume_swap_dev_t) {
+		if (quiet)
+			return 1;
+
+		if (test_toi_state(TOI_TRYING_TO_RESUME))
+			toi_early_boot_message(1, TOI_CONTINUE_REQ,
+			  "Failed to translate \"%s\" into a device id.\n",
+			  commandline);
+		else
+			printk("TuxOnIce: Can't translate \"%s\" into a device "
+					"id yet.\n", commandline);
+		return 1;
+	}
+
+	resume_block_device = open_bdev(MAX_SWAPFILES, resume_swap_dev_t, 0);
+	if (IS_ERR(resume_block_device)) {
+		if (!quiet)
+			toi_early_boot_message(1, TOI_CONTINUE_REQ,
+				"Failed to get access to \"%s\", where"
+				" the swap header should be found.",
+				commandline);
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * If we have read part of the image, we might have filled  memory with
+ * data that should be zeroed out.
+ */
+static void toi_swap_noresume_reset(void)
+{
+	toi_bio_ops.rw_cleanup(READ);
+	memset((char *) &devinfo, 0, sizeof(devinfo));
+}
+
+static int get_current_signature(void)
+{
+	if (!current_signature_page) {
+		current_signature_page = (char *) toi_get_zeroed_page(38,
+			TOI_ATOMIC_GFP);
+		if (!current_signature_page)
+			return -ENOMEM;
+	}
+
+	return toi_bio_ops.bdev_page_io(READ, resume_block_device,
+		resume_firstblock, virt_to_page(current_signature_page));
+}
+
+static int parse_signature(void)
+{
+	union p_diskpage swap_header_page;
+	struct sig_data *sig;
+	int type;
+	char *swap_header;
+	const char *sigs[] = {
+		"SWAP-SPACE", "SWAPSPACE2", "S1SUSP", "S2SUSP", "S1SUSPEND"
+	};
+
+	int result = get_current_signature();
+	if (result)
+		return result;
+
+	swap_header_page = (union p_diskpage) current_signature_page;
+	sig = (struct sig_data *) current_signature_page;
+	swap_header = swap_header_page.pointer->swh.magic.magic;
+
+	for (type = 0; type < 5; type++)
+		if (!memcmp(sigs[type], swap_header, strlen(sigs[type])))
+			return type;
+
+	if (memcmp(tuxonice_signature, swap_header, sizeof(tuxonice_signature)))
+		return -1;
+
+	header_dev_t = sig->device;
+	clear_toi_state(TOI_RESUMED_BEFORE);
+	if (sig->resume_attempted)
+		set_toi_state(TOI_RESUMED_BEFORE);
+	headerblock = sig->sector;
+
+	return 10;
+}
+
+static void forget_signatures(void)
+{
+	if (current_signature_page) {
+		toi_free_page(38, (unsigned long) current_signature_page);
+		current_signature_page = NULL;
+	}
+}
+
+/*
+ * write_modified_signature
+ *
+ * Write a (potentially) modified signature page without forgetting the
+ * original contents.
+ */
+static int write_modified_signature(int modification)
+{
+	union p_diskpage swap_header_page;
+	struct swap_info_struct *si;
+	int result;
+	char *orig_sig;
+
+	/* In case we haven't already */
+	result = get_current_signature();
+
+	if (result)
+		return result;
+
+	swap_header_page.address = toi_get_zeroed_page(38, TOI_ATOMIC_GFP);
+
+	if (!swap_header_page.address)
+		return -ENOMEM;
+
+	memcpy(swap_header_page.ptr, current_signature_page, PAGE_SIZE);
+
+	switch (modification) {
+	case IMAGE_SIGNATURE:
+
+		memcpy(no_image_signature_contents, swap_header_page.ptr,
+				sizeof(no_image_signature_contents));
+
+		/* Get the details of the header first page. */
+		toi_extent_state_goto_start(&toi_writer_posn);
+		toi_bio_ops.forward_one_page(1, 1);
+
+		si = get_swap_info_struct(toi_writer_posn.current_chain);
+
+		/* Prepare the signature */
+		swap_header_page.pointer->sig_data.device = si->bdev->bd_dev;
+		swap_header_page.pointer->sig_data.sector =
+			toi_writer_posn.current_offset;
+		swap_header_page.pointer->sig_data.resume_attempted = 0;
+		swap_header_page.pointer->sig_data.orig_sig_type =
+			parse_signature();
+
+		memcpy(swap_header_page.pointer->swh.magic.magic,
+				tuxonice_signature, sizeof(tuxonice_signature));
+
+		break;
+	case NO_IMAGE_SIGNATURE:
+		if (!swap_header_page.pointer->sig_data.orig_sig_type)
+			orig_sig = "SWAP-SPACE";
+		else
+			orig_sig = "SWAPSPACE2";
+
+		memcpy(swap_header_page.pointer->swh.magic.magic, orig_sig, 10);
+		memcpy(swap_header_page.ptr, no_image_signature_contents,
+				sizeof(no_image_signature_contents));
+		break;
+	case TRIED_RESUME:
+		swap_header_page.pointer->sig_data.resume_attempted = 1;
+		break;
+	case NO_TRIED_RESUME:
+		swap_header_page.pointer->sig_data.resume_attempted = 0;
+		break;
+	}
+
+	result = toi_bio_ops.bdev_page_io(WRITE, resume_block_device,
+		resume_firstblock, virt_to_page(swap_header_page.address));
+
+	memcpy(current_signature_page, swap_header_page.ptr, PAGE_SIZE);
+
+	toi_free_page(38, swap_header_page.address);
+
+	return result;
+}
+
+/*
+ * apply_header_reservation
+ */
+static int apply_header_reservation(void)
+{
+	int i;
+
+	toi_extent_state_goto_start(&toi_writer_posn);
+
+	for (i = 0; i < header_pages_reserved; i++)
+		if (toi_bio_ops.forward_one_page(1, 0))
+			return -ENOSPC;
+
+	/* The end of header pages will be the start of pageset 2;
+	 * we are now sitting on the first pageset2 page. */
+	toi_extent_state_save(&toi_writer_posn, &toi_writer_posn_save[2]);
+	return 0;
+}
+
+static void toi_swap_reserve_header_space(int request)
+{
+	header_pages_reserved = (long) request;
+}
+
+static void free_block_chains(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_SWAPFILES; i++)
+		if (block_chain[i].first)
+			toi_put_extent_chain(&block_chain[i]);
+}
+
+static int add_blocks_to_extent_chain(int chain, int start, int end)
+{
+	if (test_action_state(TOI_TEST_BIO))
+		printk(KERN_INFO "Adding extent chain %d %d-%d.\n", chain,
+				start << devinfo[chain].bmap_shift,
+				end << devinfo[chain].bmap_shift);
+
+	if (toi_add_to_extent_chain(&block_chain[chain], start, end)) {
+		free_block_chains();
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+
+static int get_main_pool_phys_params(void)
+{
+	struct hibernate_extent *extentpointer = NULL;
+	unsigned long address;
+	int extent_min = -1, extent_max = -1, last_chain = -1;
+
+	free_block_chains();
+
+	toi_extent_for_each(&swapextents, extentpointer, address) {
+		swp_entry_t swap_address = (swp_entry_t) { address };
+		pgoff_t offset = swp_offset(swap_address);
+		unsigned swapfilenum = swp_type(swap_address);
+		struct swap_info_struct *sis =
+			get_swap_info_struct(swapfilenum);
+		sector_t new_sector = map_swap_page(sis, offset);
+
+		if (devinfo[swapfilenum].ignored)
+			continue;
+
+		if ((new_sector == extent_max + 1) &&
+		    (last_chain == swapfilenum)) {
+			extent_max++;
+			continue;
+		}
+
+		if (extent_min > -1 && add_blocks_to_extent_chain(last_chain,
+					extent_min, extent_max)) {
+			printk(KERN_ERR "Out of memory while making block "
+					"chains.\n");
+			return -ENOMEM;
+		}
+
+		extent_min = new_sector;
+		extent_max = new_sector;
+		last_chain = swapfilenum;
+	}
+
+	if (extent_min > -1 && add_blocks_to_extent_chain(last_chain,
+				extent_min, extent_max)) {
+		printk(KERN_ERR "Out of memory while making block chains.\n");
+		return -ENOMEM;
+	}
+
+	return apply_header_reservation();
+}
+
+static long raw_to_real(long raw)
+{
+	long result;
+
+	result = raw - (raw * (sizeof(unsigned long) + sizeof(int)) +
+		(PAGE_SIZE + sizeof(unsigned long) + sizeof(int) + 1)) /
+		(PAGE_SIZE + sizeof(unsigned long) + sizeof(int));
+
+	return result < 0 ? 0 : result;
+}
+
+static int toi_swap_storage_allocated(void)
+{
+	return (int) raw_to_real(swap_pages_allocated - header_pages_reserved);
+}
+
+/*
+ * Like si_swapinfo, except that we don't include ram backed swap (compcache!)
+ * and don't need to use the spinlocks (userspace is stopped when this
+ * function is called).
+ */
+void si_swapinfo_no_compcache(struct sysinfo *val)
+{
+	unsigned int i;
+
+	si_swapinfo(&swapinfo);
+	val->freeswap = 0;
+	val->totalswap = 0;
+
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		struct swap_info_struct *si = get_swap_info_struct(i);
+		if ((si->flags & SWP_USED) && si->swap_map &&
+		    (si->flags & SWP_WRITEOK) &&
+		    (strncmp(si->bdev->bd_disk->disk_name, "ram", 3))) {
+			val->totalswap += si->inuse_pages;
+			val->freeswap += si->pages - si->inuse_pages;
+		}
+	}
+}
+/*
+ * We can't just remember the value from allocation time, because other
+ * processes might have allocated swap in the mean time.
+ */
+static int toi_swap_storage_available(void)
+{
+	si_swapinfo_no_compcache(&swapinfo);
+	return (int) raw_to_real((long) swapinfo.freeswap +
+			swap_pages_allocated - header_pages_reserved);
+}
+
+static int toi_swap_initialise(int starting_cycle)
+{
+	int result = 0;
+
+	if (!starting_cycle)
+		return 0;
+
+	enable_swapfile();
+
+	if (resume_swap_dev_t && !resume_block_device) {
+		resume_block_device = open_bdev(MAX_SWAPFILES,
+				resume_swap_dev_t, 1);
+		if (IS_ERR(resume_block_device))
+			result = 1;
+	}
+
+	return result;
+}
+
+static void toi_swap_cleanup(int ending_cycle)
+{
+	if (ending_cycle)
+		disable_swapfile();
+
+	close_bdevs();
+
+	forget_signatures();
+}
+
+static int toi_swap_release_storage(void)
+{
+	header_pages_reserved = 0;
+	swap_pages_allocated = 0;
+
+	if (swapextents.first) {
+		/* Free swap entries */
+		struct hibernate_extent *extentpointer;
+		unsigned long extentvalue;
+		toi_extent_for_each(&swapextents, extentpointer,
+				extentvalue)
+			swap_free((swp_entry_t) { extentvalue });
+
+		toi_put_extent_chain(&swapextents);
+
+		free_block_chains();
+	}
+
+	return 0;
+}
+
+static void free_swap_range(unsigned long min, unsigned long max)
+{
+	int j;
+
+	for (j = min; j <= max; j++)
+		swap_free((swp_entry_t) { j });
+}
+
+/*
+ * Round robin allocation (where swap storage has the same priority).
+ * could make this very inefficient, so we track extents allocated on
+ * a per-swapfile basis.
+ */
+static int toi_swap_allocate_storage(int request)
+{
+	int i, result = 0, to_add[MAX_SWAPFILES], pages_to_get, extra_pages,
+	    gotten = 0, result2;
+	unsigned long extent_min[MAX_SWAPFILES], extent_max[MAX_SWAPFILES];
+
+	extra_pages = DIV_ROUND_UP(request * (sizeof(unsigned long)
+			       + sizeof(int)), PAGE_SIZE);
+	pages_to_get = request + extra_pages - swapextents.size +
+		header_pages_reserved;
+
+	if (pages_to_get < 1)
+		return apply_header_reservation();
+
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		struct swap_info_struct *si = get_swap_info_struct(i);
+		to_add[i] = 0;
+		if (!(si->flags & SWP_USED) || !si->swap_map ||
+		    !(si->flags & SWP_WRITEOK))
+			continue;
+		if (!strncmp(si->bdev->bd_disk->disk_name, "ram", 3)) {
+			devinfo[i].ignored = 1;
+			continue;
+		}
+		devinfo[i].ignored = 0;
+		devinfo[i].bdev = si->bdev;
+		devinfo[i].dev_t = si->bdev->bd_dev;
+		devinfo[i].bmap_shift = 3;
+		devinfo[i].blocks_per_page = 1;
+	}
+
+	while (gotten < pages_to_get) {
+		swp_entry_t entry;
+		unsigned long new_value;
+		unsigned swapfilenum;
+
+		entry = get_swap_page();
+		if (!entry.val)
+			break;
+
+		swapfilenum = swp_type(entry);
+		new_value = entry.val;
+
+		if (!to_add[swapfilenum]) {
+			to_add[swapfilenum] = 1;
+			extent_min[swapfilenum] = new_value;
+			extent_max[swapfilenum] = new_value;
+			if (!devinfo[swapfilenum].ignored)
+				gotten++;
+			continue;
+		}
+
+		if (new_value == extent_max[swapfilenum] + 1) {
+			extent_max[swapfilenum]++;
+			if (!devinfo[swapfilenum].ignored)
+				gotten++;
+			continue;
+		}
+
+		if (toi_add_to_extent_chain(&swapextents,
+					extent_min[swapfilenum],
+					extent_max[swapfilenum])) {
+			printk(KERN_INFO "Failed to allocate extent for "
+					"%lu-%lu.\n", extent_min[swapfilenum],
+					extent_max[swapfilenum]);
+			free_swap_range(extent_min[swapfilenum],
+					extent_max[swapfilenum]);
+			swap_free(entry);
+			if (!devinfo[swapfilenum].ignored)
+				gotten -= (extent_max[swapfilenum] -
+					extent_min[swapfilenum] + 1);
+			/* Don't try to add again below */
+			to_add[swapfilenum] = 0;
+			break;
+		} else {
+			extent_min[swapfilenum] = new_value;
+			extent_max[swapfilenum] = new_value;
+			if (!devinfo[swapfilenum].ignored)
+				gotten++;
+		}
+	}
+
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		int this_result;
+
+		/* Anything to do for this swap entry? */
+		if (!to_add[i])
+			continue;
+
+		this_result = toi_add_to_extent_chain(&swapextents,
+				extent_min[i], extent_max[i]);
+
+		/* Added okay? */
+		if (!this_result)
+			continue;
+
+		/* 
+		 * Nope. Remember an error occured, free the swap and subtract
+		 * from the amount of swap allocated.
+		 */
+		result = this_result;
+
+		free_swap_range(extent_min[i], extent_max[i]);
+		if (!devinfo[i].ignored)
+			gotten -= (extent_max[i] - extent_min[i] + 1);
+	}
+
+	if (gotten < pages_to_get) {
+		printk("Got fewer pages than required "
+				"(%d wanted, %d gotten).\n",
+				pages_to_get, gotten);
+		result = -ENOSPC;
+	}
+
+	swap_pages_allocated += (long) gotten;
+
+	result2 = get_main_pool_phys_params();
+
+	return result ? result : result2;
+}
+
+static int toi_swap_write_header_init(void)
+{
+	int i, result;
+	struct swap_info_struct *si;
+
+	toi_bio_ops.rw_init(WRITE, 0);
+	toi_writer_buffer_posn = 0;
+
+	/* Info needed to bootstrap goes at the start of the header.
+	 * First we save the positions and devinfo, including the number
+	 * of header pages. Then we save the structs containing data needed
+	 * for reading the header pages back.
+	 * Note that even if header pages take more than one page, when we
+	 * read back the info, we will have restored the location of the
+	 * next header page by the time we go to use it.
+	 */
+
+	result = toi_bio_ops.rw_header_chunk(WRITE, &toi_swapops,
+			(char *) &no_image_signature_contents,
+			sizeof(struct sig_data));
+
+	if (result)
+		return result;
+
+	/* Forward one page will be done prior to the read */
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		si = get_swap_info_struct(i);
+		if (si->swap_file)
+			devinfo[i].dev_t = si->bdev->bd_dev;
+		else
+			devinfo[i].dev_t = (dev_t) 0;
+	}
+
+	result = toi_bio_ops.rw_header_chunk(WRITE, &toi_swapops,
+			(char *) &toi_writer_posn_save,
+			sizeof(toi_writer_posn_save));
+
+	if (result)
+		return result;
+
+	result = toi_bio_ops.rw_header_chunk(WRITE, &toi_swapops,
+			(char *) &devinfo, sizeof(devinfo));
+
+	if (result)
+		return result;
+
+	for (i = 0; i < MAX_SWAPFILES; i++)
+		toi_serialise_extent_chain(&toi_swapops, &block_chain[i]);
+
+	return 0;
+}
+
+static int toi_swap_write_header_cleanup(void)
+{
+	int result = toi_bio_ops.write_header_chunk_finish();
+
+	/* Set signature to save we have an image */
+	if (!result)
+		result = write_modified_signature(IMAGE_SIGNATURE);
+
+	return result;
+}
+
+/* ------------------------- HEADER READING ------------------------- */
+
+/*
+ * read_header_init()
+ *
+ * Description:
+ * 1. Attempt to read the device specified with resume=.
+ * 2. Check the contents of the swap header for our signature.
+ * 3. Warn, ignore, reset and/or continue as appropriate.
+ * 4. If continuing, read the toi_swap configuration section
+ *    of the header and set up block device info so we can read
+ *    the rest of the header & image.
+ *
+ * Returns:
+ * May not return if user choose to reboot at a warning.
+ * -EINVAL if cannot resume at this time. Booting should continue
+ * normally.
+ */
+
+static int toi_swap_read_header_init(void)
+{
+	int i, result = 0;
+	toi_writer_buffer_posn = 0;
+
+	if (!header_dev_t) {
+		printk(KERN_INFO "read_header_init called when we haven't "
+				"verified there is an image!\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * If the header is not on the resume_swap_dev_t, get the resume device
+	 * first.
+	 */
+	if (header_dev_t != resume_swap_dev_t) {
+		header_block_device = open_bdev(MAX_SWAPFILES + 1,
+				header_dev_t, 1);
+
+		if (IS_ERR(header_block_device))
+			return PTR_ERR(header_block_device);
+	} else
+		header_block_device = resume_block_device;
+
+	toi_bio_ops.read_header_init();
+
+	/*
+	 * Read toi_swap configuration.
+	 * Headerblock size taken into account already.
+	 */
+	result = toi_bio_ops.bdev_page_io(READ, header_block_device,
+			headerblock << 3,
+			virt_to_page((unsigned long) toi_writer_buffer));
+	if (result)
+		return result;
+
+	memcpy(&no_image_signature_contents, toi_writer_buffer,
+			sizeof(no_image_signature_contents));
+
+	toi_writer_buffer_posn = sizeof(no_image_signature_contents);
+
+	memcpy(&toi_writer_posn_save, toi_writer_buffer +
+			toi_writer_buffer_posn, sizeof(toi_writer_posn_save));
+
+	toi_writer_buffer_posn += sizeof(toi_writer_posn_save);
+
+	memcpy(&devinfo, toi_writer_buffer + toi_writer_buffer_posn,
+			sizeof(devinfo));
+
+	toi_writer_buffer_posn += sizeof(devinfo);
+
+	/* Restore device info */
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		dev_t thisdevice = devinfo[i].dev_t;
+		struct block_device *bdev_result;
+
+		devinfo[i].bdev = NULL;
+
+		if (!thisdevice || devinfo[i].ignored)
+			continue;
+
+		if (thisdevice == resume_swap_dev_t) {
+			devinfo[i].bdev = resume_block_device;
+			continue;
+		}
+
+		if (thisdevice == header_dev_t) {
+			devinfo[i].bdev = header_block_device;
+			continue;
+		}
+
+		bdev_result = open_bdev(i, thisdevice, 1);
+		if (IS_ERR(bdev_result))
+			return PTR_ERR(bdev_result);
+		devinfo[i].bdev = bdevs_opened[i]->bdev;
+	}
+
+	toi_extent_state_goto_start(&toi_writer_posn);
+	toi_bio_ops.set_extra_page_forward();
+
+	for (i = 0; i < MAX_SWAPFILES && !result; i++)
+		result = toi_load_extent_chain(&block_chain[i]);
+
+	return result;
+}
+
+static int toi_swap_read_header_cleanup(void)
+{
+	toi_bio_ops.rw_cleanup(READ);
+	return 0;
+}
+
+/*
+ * workspace_size
+ *
+ * Description:
+ * Returns the number of bytes of RAM needed for this
+ * code to do its work. (Used when calculating whether
+ * we have enough memory to be able to hibernate & resume).
+ *
+ */
+static int toi_swap_memory_needed(void)
+{
+	return 1;
+}
+
+/*
+ * Print debug info
+ *
+ * Description:
+ */
+static int toi_swap_print_debug_stats(char *buffer, int size)
+{
+	int len = 0;
+	struct sysinfo sysinfo;
+
+	if (toiActiveAllocator != &toi_swapops) {
+		len = scnprintf(buffer, size,
+				"- SwapAllocator inactive.\n");
+		return len;
+	}
+
+	len = scnprintf(buffer, size, "- SwapAllocator active.\n");
+	if (swapfilename[0])
+		len += scnprintf(buffer+len, size-len,
+			"  Attempting to automatically swapon: %s.\n",
+			swapfilename);
+
+	si_swapinfo_no_compcache(&sysinfo);
+
+	len += scnprintf(buffer+len, size-len,
+			"  Swap available for image: %d pages.\n",
+			(int) sysinfo.freeswap + toi_swap_storage_allocated());
+
+	return len;
+}
+
+/*
+ * Storage needed
+ *
+ * Returns amount of space in the swap header required
+ * for the toi_swap's data. This ignores the links between
+ * pages, which we factor in when allocating the space.
+ *
+ * We ensure the space is allocated, but actually save the
+ * data from write_header_init and therefore don't also define a
+ * save_config_info routine.
+ */
+static int toi_swap_storage_needed(void)
+{
+	int i, result;
+	result = sizeof(struct sig_data) + sizeof(toi_writer_posn_save) +
+		sizeof(devinfo);
+
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		result += 2 * sizeof(int);
+		result += (2 * sizeof(unsigned long) *
+			block_chain[i].num_extents);
+	}
+
+	return result;
+}
+
+/*
+ * Image_exists
+ *
+ * Returns -1 if don't know, otherwise 0 (no) or 1 (yes).
+ */
+static int toi_swap_image_exists(int quiet)
+{
+	int signature_found;
+
+	if (!resume_swap_dev_t) {
+		if (!quiet)
+			printk(KERN_INFO "Not even trying to read header "
+				"because resume_swap_dev_t is not set.\n");
+		return -1;
+	}
+
+	if (!resume_block_device) {
+		resume_block_device = open_bdev(MAX_SWAPFILES,
+				resume_swap_dev_t, 1);
+		if (IS_ERR(resume_block_device)) {
+			if (!quiet)
+				printk(KERN_INFO "Failed to open resume dev_t"
+						" (%x).\n", resume_swap_dev_t);
+			return -1;
+		}
+	}
+
+	signature_found = parse_signature();
+
+	switch (signature_found) {
+	case -ENOMEM:
+		return -1;
+	case -1:
+		if (!quiet)
+			printk(KERN_ERR "TuxOnIce: Unable to find a signature."
+				" Could you have moved a swap file?\n");
+		return -1;
+	case 0:
+	case 1:
+		if (!quiet)
+			printk(KERN_INFO "TuxOnIce: Normal swapspace found.\n");
+		return 0;
+	case 2:
+	case 3:
+	case 4:
+		if (!quiet)
+			printk(KERN_INFO "TuxOnIce: Detected another "
+				"implementation's signature.\n");
+		return 0;
+	case 10:
+		if (!quiet)
+			printk(KERN_INFO "TuxOnIce: Detected TuxOnIce binary "
+				"signature.\n");
+		return 1;
+	}
+
+	printk("Unrecognised parse_signature result (%d).\n", signature_found);
+	return 0;
+}
+
+/* toi_swap_remove_image
+ *
+ */
+static int toi_swap_remove_image(void)
+{
+	/*
+	 * If nr_hibernates == 0, we must be booting, so no swap pages
+	 * will be recorded as used yet.
+	 */
+
+	if (nr_hibernates)
+		toi_swap_release_storage();
+
+	/*
+	 * We don't do a sanity check here: we want to restore the swap
+	 * whatever version of kernel made the hibernate image.
+	 *
+	 * We need to write swap, but swap may not be enabled so
+	 * we write the device directly
+	 *
+	 * If we don't have an current_signature_page, we didn't
+	 * read an image header, so don't change anything.
+	 */
+
+	return toi_swap_image_exists(1) ?
+		write_modified_signature(NO_IMAGE_SIGNATURE) : 0;
+}
+
+/*
+ * Mark resume attempted.
+ *
+ * Record that we tried to resume from this image. We have already read the
+ * signature in. We just need to write the modified version.
+ */
+static int toi_swap_mark_resume_attempted(int mark)
+{
+	if (!resume_swap_dev_t) {
+		printk(KERN_INFO "Not even trying to record attempt at resuming"
+				" because resume_swap_dev_t is not set.\n");
+		return -ENODEV;
+	}
+
+	return write_modified_signature(mark ? TRIED_RESUME : NO_TRIED_RESUME);
+}
+
+/*
+ * Parse Image Location
+ *
+ * Attempt to parse a resume= parameter.
+ * Swap Writer accepts:
+ * resume=swap:DEVNAME[:FIRSTBLOCK][@BLOCKSIZE]
+ *
+ * Where:
+ * DEVNAME is convertable to a dev_t by name_to_dev_t
+ * FIRSTBLOCK is the location of the first block in the swap file
+ * (specifying for a swap partition is nonsensical but not prohibited).
+ * Data is validated by attempting to read a swap header from the
+ * location given. Failure will result in toi_swap refusing to
+ * save an image, and a reboot with correct parameters will be
+ * necessary.
+ */
+static int toi_swap_parse_sig_location(char *commandline,
+		int only_allocator, int quiet)
+{
+	char *thischar, *devstart, *colon = NULL;
+	int signature_found, result = -EINVAL, temp_result = 0;
+
+	if (strncmp(commandline, "swap:", 5)) {
+		/*
+		 * Failing swap:, we'll take a simple
+		 * resume=/dev/hda2, but fall through to
+		 * other allocators if /dev/ isn't matched.
+		 */
+		if (strncmp(commandline, "/dev/", 5))
+			return 1;
+	} else
+		commandline += 5;
+
+	devstart = commandline;
+	thischar = commandline;
+	while ((*thischar != ':') && (*thischar != '@') &&
+		((thischar - commandline) < 250) && (*thischar))
+		thischar++;
+
+	if (*thischar == ':') {
+		colon = thischar;
+		*colon = 0;
+		thischar++;
+	}
+
+	while ((thischar - commandline) < 250 && *thischar)
+		thischar++;
+
+	if (colon) {
+		unsigned long block;
+		temp_result = strict_strtoul(colon + 1, 0, &block);
+		if (!temp_result)
+			resume_firstblock = (int) block;
+	} else
+		resume_firstblock = 0;
+
+	clear_toi_state(TOI_CAN_HIBERNATE);
+	clear_toi_state(TOI_CAN_RESUME);
+
+	if (!temp_result)
+		temp_result = try_to_parse_resume_device(devstart, quiet);
+
+	if (colon)
+		*colon = ':';
+
+	if (temp_result)
+		return -EINVAL;
+
+	signature_found = toi_swap_image_exists(quiet);
+
+	if (signature_found != -1) {
+		result = 0;
+
+		toi_bio_ops.set_devinfo(devinfo);
+		toi_writer_posn.chains = &block_chain[0];
+		toi_writer_posn.num_chains = MAX_SWAPFILES;
+		set_toi_state(TOI_CAN_HIBERNATE);
+		set_toi_state(TOI_CAN_RESUME);
+	} else
+		if (!quiet)
+			printk(KERN_ERR "TuxOnIce: SwapAllocator: No swap "
+				"signature found at %s.\n", devstart);
+	return result;
+}
+
+static int header_locations_read_sysfs(const char *page, int count)
+{
+	int i, printedpartitionsmessage = 0, len = 0, haveswap = 0;
+	struct inode *swapf = NULL;
+	int zone;
+	char *path_page = (char *) toi_get_free_page(10, GFP_KERNEL);
+	char *path, *output = (char *) page;
+	int path_len;
+
+	if (!page)
+		return 0;
+
+	for (i = 0; i < MAX_SWAPFILES; i++) {
+		struct swap_info_struct *si =  get_swap_info_struct(i);
+
+		if (!si->swap_file)
+			continue;
+
+		if (S_ISBLK(si->swap_file->f_mapping->host->i_mode)) {
+			haveswap = 1;
+			if (!printedpartitionsmessage) {
+				len += sprintf(output + len,
+					"For swap partitions, simply use the "
+					"format: resume=swap:/dev/hda1.\n");
+				printedpartitionsmessage = 1;
+			}
+		} else {
+			path_len = 0;
+
+			path = d_path(&si->swap_file->f_path, path_page,
+					PAGE_SIZE);
+			path_len = snprintf(path_page, 31, "%s", path);
+
+			haveswap = 1;
+			swapf = si->swap_file->f_mapping->host;
+			zone = bmap(swapf, 0);
+			if (!zone) {
+				len += sprintf(output + len,
+					"Swapfile %s has been corrupted. Reuse"
+					" mkswap on it and try again.\n",
+					path_page);
+			} else {
+				char name_buffer[255];
+				len += sprintf(output + len,
+					"For swapfile `%s`,"
+					" use resume=swap:/dev/%s:0x%x.\n",
+					path_page,
+					bdevname(si->bdev, name_buffer),
+					zone << (swapf->i_blkbits - 9));
+			}
+		}
+	}
+
+	if (!haveswap)
+		len = sprintf(output, "You need to turn on swap partitions "
+				"before examining this file.\n");
+
+	toi_free_page(10, (unsigned long) path_page);
+	return len;
+}
+
+static struct toi_sysfs_data sysfs_params[] = {
+	SYSFS_STRING("swapfilename", SYSFS_RW, swapfilename, 255, 0, NULL),
+	SYSFS_CUSTOM("headerlocations", SYSFS_READONLY,
+			header_locations_read_sysfs, NULL, 0, NULL),
+	SYSFS_INT("enabled", SYSFS_RW, &toi_swapops.enabled, 0, 1, 0,
+			attempt_to_parse_resume_device2),
+};
+
+static struct toi_module_ops toi_swapops = {
+	.type					= WRITER_MODULE,
+	.name					= "swap storage",
+	.directory				= "swap",
+	.module					= THIS_MODULE,
+	.memory_needed				= toi_swap_memory_needed,
+	.print_debug_info			= toi_swap_print_debug_stats,
+	.storage_needed				= toi_swap_storage_needed,
+	.initialise				= toi_swap_initialise,
+	.cleanup				= toi_swap_cleanup,
+
+	.noresume_reset		= toi_swap_noresume_reset,
+	.storage_available 	= toi_swap_storage_available,
+	.storage_allocated	= toi_swap_storage_allocated,
+	.reserve_header_space	= toi_swap_reserve_header_space,
+	.allocate_storage	= toi_swap_allocate_storage,
+	.image_exists		= toi_swap_image_exists,
+	.mark_resume_attempted	= toi_swap_mark_resume_attempted,
+	.write_header_init	= toi_swap_write_header_init,
+	.write_header_cleanup	= toi_swap_write_header_cleanup,
+	.read_header_init	= toi_swap_read_header_init,
+	.read_header_cleanup	= toi_swap_read_header_cleanup,
+	.remove_image		= toi_swap_remove_image,
+	.parse_sig_location	= toi_swap_parse_sig_location,
+
+	.sysfs_data		= sysfs_params,
+	.num_sysfs_entries	= sizeof(sysfs_params) /
+		sizeof(struct toi_sysfs_data),
+};
+
+/* ---- Registration ---- */
+static __init int toi_swap_load(void)
+{
+	toi_swapops.rw_init = toi_bio_ops.rw_init;
+	toi_swapops.rw_cleanup = toi_bio_ops.rw_cleanup;
+	toi_swapops.read_page = toi_bio_ops.read_page;
+	toi_swapops.write_page = toi_bio_ops.write_page;
+	toi_swapops.rw_header_chunk = toi_bio_ops.rw_header_chunk;
+	toi_swapops.rw_header_chunk_noreadahead =
+		toi_bio_ops.rw_header_chunk_noreadahead;
+	toi_swapops.io_flusher = toi_bio_ops.io_flusher;
+	toi_swapops.update_throughput_throttle =
+		toi_bio_ops.update_throughput_throttle;
+	toi_swapops.finish_all_io = toi_bio_ops.finish_all_io;
+
+	return toi_register_module(&toi_swapops);
+}
+
+late_initcall(toi_swap_load);
-- 
1.5.6.3

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