7 files changed, 475 insertions, 7 deletions

diff --git a/Documentation/power/userland-swsusp.txt b/Documentation/power/userland-swsusp.txt
new file mode 100644
index 000000000000..94058220aaf0
--- /dev/null
+++ b/Documentation/power/userland-swsusp.txt
@@ -0,0 +1,149 @@
+Documentation for userland software suspend interface
+        (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
+
+First, the warnings at the beginning of swsusp.txt still apply.
+
+Second, you should read the FAQ in swsusp.txt _now_ if you have not
+done it already.
+
+Now, to use the userland interface for software suspend you need special
+utilities that will read/write the system memory snapshot from/to the
+kernel.  Such utilities are available, for example, from
+<http://www.sisk.pl/kernel/utilities/suspend>.  You may want to have
+a look at them if you are going to develop your own suspend/resume
+utilities.
+
+The interface consists of a character device providing the open(),
+release(), read(), and write() operations as well as several ioctl()
+commands defined in kernel/power/power.h.  The major and minor
+numbers of the device are, respectively, 10 and 231, and they can
+be read from /sys/class/misc/snapshot/dev.
+
+The device can be open either for reading or for writing.  If open for
+reading, it is considered to be in the suspend mode.  Otherwise it is
+assumed to be in the resume mode.  The device cannot be open for reading
+and writing.  It is also impossible to have the device open more than once
+at a time.
+
+The ioctl() commands recognized by the device are:
+
+SNAPSHOT_FREEZE - freeze user space processes (the current process is
+        not frozen); this is required for SNAPSHOT_ATOMIC_SNAPSHOT
+        and SNAPSHOT_ATOMIC_RESTORE to succeed
+
+SNAPSHOT_UNFREEZE - thaw user space processes frozen by SNAPSHOT_FREEZE
+
+SNAPSHOT_ATOMIC_SNAPSHOT - create a snapshot of the system memory; the
+        last argument of ioctl() should be a pointer to an int variable,
+        the value of which will indicate whether the call returned after
+        creating the snapshot (1) or after restoring the system memory state
+        from it (0) (after resume the system finds itself finishing the
+        SNAPSHOT_ATOMIC_SNAPSHOT ioctl() again); after the snapshot
+        has been created the read() operation can be used to transfer
+        it out of the kernel
+
+SNAPSHOT_ATOMIC_RESTORE - restore the system memory state from the
+        uploaded snapshot image; before calling it you should transfer
+        the system memory snapshot back to the kernel using the write()
+        operation; this call will not succeed if the snapshot
+        image is not available to the kernel
+
+SNAPSHOT_FREE - free memory allocated for the snapshot image
+
+SNAPSHOT_SET_IMAGE_SIZE - set the preferred maximum size of the image
+        (the kernel will do its best to ensure the image size will not exceed
+        this number, but if it turns out to be impossible, the kernel will
+        create the smallest image possible)
+
+SNAPSHOT_AVAIL_SWAP - return the amount of available swap in bytes (the last
+        argument should be a pointer to an unsigned int variable that will
+        contain the result if the call is successful).
+
+SNAPSHOT_GET_SWAP_PAGE - allocate a swap page from the resume partition
+        (the last argument should be a pointer to a loff_t variable that
+        will contain the swap page offset if the call is successful)
+
+SNAPSHOT_FREE_SWAP_PAGES - free all swap pages allocated with
+        SNAPSHOT_GET_SWAP_PAGE
+
+SNAPSHOT_SET_SWAP_FILE - set the resume partition (the last ioctl() argument
+        should specify the device's major and minor numbers in the old
+        two-byte format, as returned by the stat() function in the .st_rdev
+        member of the stat structure); it is recommended to always use this
+        call, because the code to set the resume partition could be removed from
+        future kernels
+
+The device's read() operation can be used to transfer the snapshot image from
+the kernel.  It has the following limitations:
+- you cannot read() more than one virtual memory page at a time
+- read()s accross page boundaries are impossible (ie. if ypu read() 1/2 of
+        a page in the previous call, you will only be able to read()
+        _at_ _most_ 1/2 of the page in the next call)
+
+The device's write() operation is used for uploading the system memory snapshot
+into the kernel.  It has the same limitations as the read() operation.
+
+The release() operation frees all memory allocated for the snapshot image
+and all swap pages allocated with SNAPSHOT_GET_SWAP_PAGE (if any).
+Thus it is not necessary to use either SNAPSHOT_FREE or
+SNAPSHOT_FREE_SWAP_PAGES before closing the device (in fact it will also
+unfreeze user space processes frozen by SNAPSHOT_UNFREEZE if they are
+still frozen when the device is being closed).
+
+Currently it is assumed that the userland utilities reading/writing the
+snapshot image from/to the kernel will use a swap parition, called the resume
+partition, as storage space.  However, this is not really required, as they
+can use, for example, a special (blank) suspend partition or a file on a partition
+that is unmounted before SNAPSHOT_ATOMIC_SNAPSHOT and mounted afterwards.
+
+These utilities SHOULD NOT make any assumptions regarding the ordering of
+data within the snapshot image, except for the image header that MAY be
+assumed to start with an swsusp_info structure, as specified in
+kernel/power/power.h.  This structure MAY be used by the userland utilities
+to obtain some information about the snapshot image, such as the size
+of the snapshot image, including the metadata and the header itself,
+contained in the .size member of swsusp_info.
+
+The snapshot image MUST be written to the kernel unaltered (ie. all of the image
+data, metadata and header MUST be written in _exactly_ the same amount, form
+and order in which they have been read).  Otherwise, the behavior of the
+resumed system may be totally unpredictable.
+
+While executing SNAPSHOT_ATOMIC_RESTORE the kernel checks if the
+structure of the snapshot image is consistent with the information stored
+in the image header.  If any inconsistencies are detected,
+SNAPSHOT_ATOMIC_RESTORE will not succeed.  Still, this is not a fool-proof
+mechanism and the userland utilities using the interface SHOULD use additional
+means, such as checksums, to ensure the integrity of the snapshot image.
+
+The suspending and resuming utilities MUST lock themselves in memory,
+preferrably using mlockall(), before calling SNAPSHOT_FREEZE.
+
+The suspending utility MUST check the value stored by SNAPSHOT_ATOMIC_SNAPSHOT
+in the memory location pointed to by the last argument of ioctl() and proceed
+in accordance with it:
+1.      If the value is 1 (ie. the system memory snapshot has just been
+        created and the system is ready for saving it):
+        (a)     The suspending utility MUST NOT close the snapshot device
+                _unless_ the whole suspend procedure is to be cancelled, in
+                which case, if the snapshot image has already been saved, the
+                suspending utility SHOULD destroy it, preferrably by zapping
+                its header.  If the suspend is not to be cancelled, the
+                system MUST be powered off or rebooted after the snapshot
+                image has been saved.
+        (b)     The suspending utility SHOULD NOT attempt to perform any
+                file system operations (including reads) on the file systems
+                that were mounted before SNAPSHOT_ATOMIC_SNAPSHOT has been
+                called.  However, it MAY mount a file system that was not
+                mounted at that time and perform some operations on it (eg.
+                use it for saving the image).
+2.      If the value is 0 (ie. the system state has just been restored from
+        the snapshot image), the suspending utility MUST close the snapshot
+        device.  Afterwards it will be treated as a regular userland process,
+        so it need not exit.
+
+The resuming utility SHOULD NOT attempt to mount any file systems that could
+be mounted before suspend and SHOULD NOT attempt to perform any operations
+involving such file systems.
+
+For details, please refer to the source code.
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index a05cabd0fd10..405f9031af87 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -56,6 +56,7 @@ static void __init handle_initrd(void)
         sys_chroot(".");
         mount_devfs_fs ();
 
+        current->flags |= PF_NOFREEZE;
         pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
         if (pid > 0) {
                 while (pid != sys_wait4(-1, NULL, 0, NULL))
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index bb91a0615303..8d0af3d37a4b 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -5,7 +5,7 @@ endif
 
 obj-y                           := main.o process.o console.o
 obj-$(CONFIG_PM_LEGACY)         += pm.o
-obj-$(CONFIG_SOFTWARE_SUSPEND)  += swsusp.o disk.o snapshot.o swap.o
+obj-$(CONFIG_SOFTWARE_SUSPEND)  += swsusp.o disk.o snapshot.o swap.o user.o
 
 obj-$(CONFIG_SUSPEND_SMP)       += smp.o
 
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 5d1abffbb9ce..42c431c8bdde 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -8,6 +8,7 @@ struct swsusp_info {
         int                     cpus;
         unsigned long           image_pages;
         unsigned long           pages;
+        unsigned long           size;
 } __attribute__((aligned(PAGE_SIZE)));
 
 
@@ -65,6 +66,19 @@ extern int snapshot_read_next(struct snapshot_handle *handle, size_t count);
 extern int snapshot_write_next(struct snapshot_handle *handle, size_t count);
 int snapshot_image_loaded(struct snapshot_handle *handle);
 
+#define SNAPSHOT_IOC_MAGIC      '3'
+#define SNAPSHOT_FREEZE                 _IO(SNAPSHOT_IOC_MAGIC, 1)
+#define SNAPSHOT_UNFREEZE               _IO(SNAPSHOT_IOC_MAGIC, 2)
+#define SNAPSHOT_ATOMIC_SNAPSHOT        _IOW(SNAPSHOT_IOC_MAGIC, 3, void *)
+#define SNAPSHOT_ATOMIC_RESTORE         _IO(SNAPSHOT_IOC_MAGIC, 4)
+#define SNAPSHOT_FREE                   _IO(SNAPSHOT_IOC_MAGIC, 5)
+#define SNAPSHOT_SET_IMAGE_SIZE         _IOW(SNAPSHOT_IOC_MAGIC, 6, unsigned long)
+#define SNAPSHOT_AVAIL_SWAP             _IOR(SNAPSHOT_IOC_MAGIC, 7, void *)
+#define SNAPSHOT_GET_SWAP_PAGE          _IOR(SNAPSHOT_IOC_MAGIC, 8, void *)
+#define SNAPSHOT_FREE_SWAP_PAGES        _IO(SNAPSHOT_IOC_MAGIC, 9)
+#define SNAPSHOT_SET_SWAP_FILE          _IOW(SNAPSHOT_IOC_MAGIC, 10, unsigned int)
+#define SNAPSHOT_IOC_MAXNR      10
+
 /**
  *      The bitmap is used for tracing allocated swap pages
  *
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index cc349437fb72..0036955357e0 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -37,6 +37,7 @@
 struct pbe *pagedir_nosave;
 static unsigned int nr_copy_pages;
 static unsigned int nr_meta_pages;
+static unsigned long *buffer;
 
 #ifdef CONFIG_HIGHMEM
 unsigned int count_highmem_pages(void)
@@ -389,7 +390,7 @@ struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask, int safe_needed
                 free_pagedir(pblist);
                 pblist = NULL;
         } else
-                create_pbe_list(pblist, nr_pages);
+                create_pbe_list(pblist, nr_pages);
         return pblist;
 }
 
@@ -418,6 +419,7 @@ void swsusp_free(void)
         nr_copy_pages = 0;
         nr_meta_pages = 0;
         pagedir_nosave = NULL;
+        buffer = NULL;
 }
 
 
@@ -523,6 +525,8 @@ static void init_header(struct swsusp_info *info)
         info->cpus = num_online_cpus();
         info->image_pages = nr_copy_pages;
         info->pages = nr_copy_pages + nr_meta_pages + 1;
+        info->size = info->pages;
+        info->size <<= PAGE_SHIFT;
 }
 
 /**
@@ -568,8 +572,6 @@ static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pb
 
 int snapshot_read_next(struct snapshot_handle *handle, size_t count)
 {
-        static unsigned long *buffer;
-
         if (handle->page > nr_meta_pages + nr_copy_pages)
                 return 0;
         if (!buffer) {
@@ -774,7 +776,6 @@ static int create_image(struct snapshot_handle *handle)
 
 int snapshot_write_next(struct snapshot_handle *handle, size_t count)
 {
-        static unsigned long *buffer;
         int error = 0;
 
         if (handle->prev && handle->page > nr_meta_pages + nr_copy_pages)
diff --git a/kernel/power/user.c b/kernel/power/user.c
new file mode 100644
index 000000000000..8cabc405ca10
--- /dev/null
+++ b/kernel/power/user.c
@@ -0,0 +1,301 @@
+/*
+ * linux/kernel/power/user.c
+ *
+ * This file provides the user space interface for software suspend/resume.
+ *
+ * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#include <linux/suspend.h>
+#include <linux/syscalls.h>
+#include <linux/string.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/pm.h>
+#include <linux/fs.h>
+
+#include <asm/uaccess.h>
+
+#include "power.h"
+
+#define SNAPSHOT_MINOR  231
+
+static struct snapshot_data {
+        struct snapshot_handle handle;
+        int swap;
+        struct bitmap_page *bitmap;
+        int mode;
+        char frozen;
+        char ready;
+} snapshot_state;
+
+static atomic_t device_available = ATOMIC_INIT(1);
+
+static int snapshot_open(struct inode *inode, struct file *filp)
+{
+        struct snapshot_data *data;
+
+        if (!atomic_add_unless(&device_available, -1, 0))
+                return -EBUSY;
+
+        if ((filp->f_flags & O_ACCMODE) == O_RDWR)
+                return -ENOSYS;
+
+        nonseekable_open(inode, filp);
+        data = &snapshot_state;
+        filp->private_data = data;
+        memset(&data->handle, 0, sizeof(struct snapshot_handle));
+        if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
+                data->swap = swsusp_resume_device ? swap_type_of(swsusp_resume_device) : -1;
+                data->mode = O_RDONLY;
+        } else {
+                data->swap = -1;
+                data->mode = O_WRONLY;
+        }
+        data->bitmap = NULL;
+        data->frozen = 0;
+        data->ready = 0;
+
+        return 0;
+}
+
+static int snapshot_release(struct inode *inode, struct file *filp)
+{
+        struct snapshot_data *data;
+
+        swsusp_free();
+        data = filp->private_data;
+        free_all_swap_pages(data->swap, data->bitmap);
+        free_bitmap(data->bitmap);
+        if (data->frozen) {
+                down(&pm_sem);
+                thaw_processes();
+                enable_nonboot_cpus();
+                up(&pm_sem);
+        }
+        atomic_inc(&device_available);
+        return 0;
+}
+
+static ssize_t snapshot_read(struct file *filp, char __user *buf,
+                             size_t count, loff_t *offp)
+{
+        struct snapshot_data *data;
+        ssize_t res;
+
+        data = filp->private_data;
+        res = snapshot_read_next(&data->handle, count);
+        if (res > 0) {
+                if (copy_to_user(buf, data_of(data->handle), res))
+                        res = -EFAULT;
+                else
+                        *offp = data->handle.offset;
+        }
+        return res;
+}
+
+static ssize_t snapshot_write(struct file *filp, const char __user *buf,
+                              size_t count, loff_t *offp)
+{
+        struct snapshot_data *data;
+        ssize_t res;
+
+        data = filp->private_data;
+        res = snapshot_write_next(&data->handle, count);
+        if (res > 0) {
+                if (copy_from_user(data_of(data->handle), buf, res))
+                        res = -EFAULT;
+                else
+                        *offp = data->handle.offset;
+        }
+        return res;
+}
+
+static int snapshot_ioctl(struct inode *inode, struct file *filp,
+                          unsigned int cmd, unsigned long arg)
+{
+        int error = 0;
+        struct snapshot_data *data;
+        loff_t offset, avail;
+
+        if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
+                return -ENOTTY;
+        if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
+                return -ENOTTY;
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        data = filp->private_data;
+
+        switch (cmd) {
+
+        case SNAPSHOT_FREEZE:
+                if (data->frozen)
+                        break;
+                sys_sync();
+                down(&pm_sem);
+                pm_prepare_console();
+                disable_nonboot_cpus();
+                if (freeze_processes()) {
+                        thaw_processes();
+                        enable_nonboot_cpus();
+                        pm_restore_console();
+                        error = -EBUSY;
+                }
+                up(&pm_sem);
+                if (!error)
+                        data->frozen = 1;
+                break;
+
+        case SNAPSHOT_UNFREEZE:
+                if (!data->frozen)
+                        break;
+                down(&pm_sem);
+                thaw_processes();
+                enable_nonboot_cpus();
+                pm_restore_console();
+                up(&pm_sem);
+                data->frozen = 0;
+                break;
+
+        case SNAPSHOT_ATOMIC_SNAPSHOT:
+                if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
+                        error = -EPERM;
+                        break;
+                }
+                down(&pm_sem);
+                /* Free memory before shutting down devices. */
+                error = swsusp_shrink_memory();
+                if (!error) {
+                        error = device_suspend(PMSG_FREEZE);
+                        if (!error) {
+                                in_suspend = 1;
+                                error = swsusp_suspend();
+                                device_resume();
+                        }
+                }
+                up(&pm_sem);
+                if (!error)
+                        error = put_user(in_suspend, (unsigned int __user *)arg);
+                if (!error)
+                        data->ready = 1;
+                break;
+
+        case SNAPSHOT_ATOMIC_RESTORE:
+                if (data->mode != O_WRONLY || !data->frozen ||
+                    !snapshot_image_loaded(&data->handle)) {
+                        error = -EPERM;
+                        break;
+                }
+                down(&pm_sem);
+                pm_prepare_console();
+                error = device_suspend(PMSG_FREEZE);
+                if (!error) {
+                        error = swsusp_resume();
+                        device_resume();
+                }
+                pm_restore_console();
+                up(&pm_sem);
+                break;
+
+        case SNAPSHOT_FREE:
+                swsusp_free();
+                memset(&data->handle, 0, sizeof(struct snapshot_handle));
+                data->ready = 0;
+                break;
+
+        case SNAPSHOT_SET_IMAGE_SIZE:
+                image_size = arg;
+                break;
+
+        case SNAPSHOT_AVAIL_SWAP:
+                avail = count_swap_pages(data->swap, 1);
+                avail <<= PAGE_SHIFT;
+                error = put_user(avail, (loff_t __user *)arg);
+                break;
+
+        case SNAPSHOT_GET_SWAP_PAGE:
+                if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
+                        error = -ENODEV;
+                        break;
+                }
+                if (!data->bitmap) {
+                        data->bitmap = alloc_bitmap(count_swap_pages(data->swap, 0));
+                        if (!data->bitmap) {
+                                error = -ENOMEM;
+                                break;
+                        }
+                }
+                offset = alloc_swap_page(data->swap, data->bitmap);
+                if (offset) {
+                        offset <<= PAGE_SHIFT;
+                        error = put_user(offset, (loff_t __user *)arg);
+                } else {
+                        error = -ENOSPC;
+                }
+                break;
+
+        case SNAPSHOT_FREE_SWAP_PAGES:
+                if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
+                        error = -ENODEV;
+                        break;
+                }
+                free_all_swap_pages(data->swap, data->bitmap);
+                free_bitmap(data->bitmap);
+                data->bitmap = NULL;
+                break;
+
+        case SNAPSHOT_SET_SWAP_FILE:
+                if (!data->bitmap) {
+                        /*
+                         * User space encodes device types as two-byte values,
+                         * so we need to recode them
+                         */
+                        if (old_decode_dev(arg)) {
+                                data->swap = swap_type_of(old_decode_dev(arg));
+                                if (data->swap < 0)
+                                        error = -ENODEV;
+                        } else {
+                                data->swap = -1;
+                                error = -EINVAL;
+                        }
+                } else {
+                        error = -EPERM;
+                }
+                break;
+
+        default:
+                error = -ENOTTY;
+
+        }
+
+        return error;
+}
+
+static struct file_operations snapshot_fops = {
+        .open = snapshot_open,
+        .release = snapshot_release,
+        .read = snapshot_read,
+        .write = snapshot_write,
+        .llseek = no_llseek,
+        .ioctl = snapshot_ioctl,
+};
+
+static struct miscdevice snapshot_device = {
+        .minor = SNAPSHOT_MINOR,
+        .name = "snapshot",
+        .fops = &snapshot_fops,
+};
+
+static int __init snapshot_device_init(void)
+{
+        return misc_register(&snapshot_device);
+};
+
+device_initcall(snapshot_device_init);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 4d11f9d84666..39aa9d129612 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -428,14 +428,16 @@ int swap_type_of(dev_t device)
 {
         int i;
 
-        if (!device)
-                return -EINVAL;
         spin_lock(&swap_lock);
         for (i = 0; i < nr_swapfiles; i++) {
                 struct inode *inode;
 
                 if (!(swap_info[i].flags & SWP_WRITEOK))
                         continue;
+                if (!device) {
+                        spin_unlock(&swap_lock);
+                        return i;
+                }
                 inode = swap_info->swap_file->f_dentry->d_inode;
                 if (S_ISBLK(inode->i_mode) &&
                     device == MKDEV(imajor(inode), iminor(inode))) {