[linux.git] / kernel / power / user.c

/*
 * linux/kernel/power/user.c
 *
 * This file provides the user space interface for software suspend/resume.
 *
 * Copyright (C) 2006 Rafael J. Wysocki <[email protected]>
 *
 * This file is released under the GPLv2.
 *
 */

#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/reboot.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 <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.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, 0, NULL) : -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) {
		mutex_lock(&pm_mutex);
		thaw_processes();
		enable_nonboot_cpus();
		mutex_unlock(&pm_mutex);
	}
	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_suspend(void)
{
	int error;

	mutex_lock(&pm_mutex);
	/* Free memory before shutting down devices. */
	error = swsusp_shrink_memory();
	if (error)
		goto Finish;

	suspend_console();
	error = device_suspend(PMSG_FREEZE);
	if (error)
		goto Resume_devices;

	error = disable_nonboot_cpus();
	if (!error) {
		in_suspend = 1;
		error = swsusp_suspend();
	}
	enable_nonboot_cpus();
 Resume_devices:
	device_resume();
	resume_console();
 Finish:
	mutex_unlock(&pm_mutex);
	return error;
}

static int snapshot_restore(void)
{
	int error;

	mutex_lock(&pm_mutex);
	pm_prepare_console();
	suspend_console();
	error = device_suspend(PMSG_PRETHAW);
	if (error)
		goto Resume_devices;

	error = disable_nonboot_cpus();
	if (!error)
		error = swsusp_resume();

	enable_nonboot_cpus();
 Resume_devices:
	device_resume();
	resume_console();
	pm_restore_console();
	mutex_unlock(&pm_mutex);
	return error;
}

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 avail;
	sector_t offset;

	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;
		mutex_lock(&pm_mutex);
		if (freeze_processes()) {
			thaw_processes();
			error = -EBUSY;
		}
		mutex_unlock(&pm_mutex);
		if (!error)
			data->frozen = 1;
		break;

	case SNAPSHOT_UNFREEZE:
		if (!data->frozen)
			break;
		mutex_lock(&pm_mutex);
		thaw_processes();
		mutex_unlock(&pm_mutex);
		data->frozen = 0;
		break;

	case SNAPSHOT_ATOMIC_SNAPSHOT:
		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
			error = -EPERM;
			break;
		}
		error = snapshot_suspend();
		if (!error)
			error = put_user(in_suspend, (unsigned int __user *)arg);
		if (!error)
			data->ready = 1;
		break;

	case SNAPSHOT_ATOMIC_RESTORE:
		snapshot_write_finalize(&data->handle);
		if (data->mode != O_WRONLY || !data->frozen ||
		    !snapshot_image_loaded(&data->handle)) {
			error = -EPERM;
			break;
		}
		error = snapshot_restore();
		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_swapdev_block(data->swap, data->bitmap);
		if (offset) {
			offset <<= PAGE_SHIFT;
			error = put_user(offset, (sector_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),
							0, NULL);
				if (data->swap < 0)
					error = -ENODEV;
			} else {
				data->swap = -1;
				error = -EINVAL;
			}
		} else {
			error = -EPERM;
		}
		break;

	case SNAPSHOT_S2RAM:
		if (!data->frozen) {
			error = -EPERM;
			break;
		}

		if (!mutex_trylock(&pm_mutex)) {
			error = -EBUSY;
			break;
		}

		if (pm_ops->prepare) {
			error = pm_ops->prepare(PM_SUSPEND_MEM);
			if (error)
				goto OutS3;
		}

		/* Put devices to sleep */
		suspend_console();
		error = device_suspend(PMSG_SUSPEND);
		if (error) {
			printk(KERN_ERR "Failed to suspend some devices.\n");
		} else {
			/* Enter S3, system is already frozen */
			suspend_enter(PM_SUSPEND_MEM);

			/* Wake up devices */
			device_resume();
		}
		resume_console();
		if (pm_ops->finish)
			pm_ops->finish(PM_SUSPEND_MEM);

 OutS3:
		mutex_unlock(&pm_mutex);
		break;

	case SNAPSHOT_PMOPS:
		switch (arg) {

		case PMOPS_PREPARE:
			if (pm_ops->prepare) {
				error = pm_ops->prepare(PM_SUSPEND_DISK);
			}
			break;

		case PMOPS_ENTER:
			kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
			error = pm_ops->enter(PM_SUSPEND_DISK);
			break;

		case PMOPS_FINISH:
			if (pm_ops && pm_ops->finish) {
				pm_ops->finish(PM_SUSPEND_DISK);
			}
			break;

		default:
			printk(KERN_ERR "SNAPSHOT_PMOPS: invalid argument %ld\n", arg);
			error = -EINVAL;

		}
		break;

	case SNAPSHOT_SET_SWAP_AREA:
		if (data->bitmap) {
			error = -EPERM;
		} else {
			struct resume_swap_area swap_area;
			dev_t swdev;

			error = copy_from_user(&swap_area, (void __user *)arg,
					sizeof(struct resume_swap_area));
			if (error) {
				error = -EFAULT;
				break;
			}

			/*
			 * User space encodes device types as two-byte values,
			 * so we need to recode them
			 */
			swdev = old_decode_dev(swap_area.dev);
			if (swdev) {
				offset = swap_area.offset;
				data->swap = swap_type_of(swdev, offset, NULL);
				if (data->swap < 0)
					error = -ENODEV;
			} else {
				data->swap = -1;
				error = -EINVAL;
			}
		}
		break;

	default:
		error = -ENOTTY;

	}

	return error;
}

static const 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);
Commit	Line	Data
6e1819d6 RW	1	/*
	2	* linux/kernel/power/user.c
	3	*
	4	* This file provides the user space interface for software suspend/resume.
	5	*
	6	* Copyright (C) 2006 Rafael J. Wysocki <[email protected]>
	7	*
	8	* This file is released under the GPLv2.
	9	*
	10	*/
	11
	12	#include <linux/suspend.h>
	13	#include <linux/syscalls.h>
3592695c	14	#include <linux/reboot.h>
6e1819d6 RW	15	#include <linux/string.h>
	16	#include <linux/device.h>
	17	#include <linux/miscdevice.h>
	18	#include <linux/mm.h>
	19	#include <linux/swap.h>
	20	#include <linux/swapops.h>
	21	#include <linux/pm.h>
	22	#include <linux/fs.h>
97c7801c	23	#include <linux/console.h>
e3920fb4	24	#include <linux/cpu.h>
7dfb7103	25	#include <linux/freezer.h>
6e1819d6 RW	26
	27	#include <asm/uaccess.h>
	28
	29	#include "power.h"
	30
	31	#define SNAPSHOT_MINOR 231
	32
	33	static struct snapshot_data {
	34	struct snapshot_handle handle;
	35	int swap;
	36	struct bitmap_page *bitmap;
	37	int mode;
	38	char frozen;
	39	char ready;
	40	} snapshot_state;
	41
	42	static atomic_t device_available = ATOMIC_INIT(1);
	43
	44	static int snapshot_open(struct inode inode, struct file filp)
	45	{
	46	struct snapshot_data *data;
	47
	48	if (!atomic_add_unless(&device_available, -1, 0))
	49	return -EBUSY;
	50
	51	if ((filp->f_flags & O_ACCMODE) == O_RDWR)
	52	return -ENOSYS;
	53
	54	nonseekable_open(inode, filp);
	55	data = &snapshot_state;
	56	filp->private_data = data;
	57	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	58	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
915bae9e	59	data->swap = swsusp_resume_device ?
7bf23687	60	swap_type_of(swsusp_resume_device, 0, NULL) : -1;
6e1819d6 RW	61	data->mode = O_RDONLY;
	62	} else {
	63	data->swap = -1;
	64	data->mode = O_WRONLY;
	65	}
	66	data->bitmap = NULL;
	67	data->frozen = 0;
	68	data->ready = 0;
	69
	70	return 0;
	71	}
	72
	73	static int snapshot_release(struct inode inode, struct file filp)
	74	{
	75	struct snapshot_data *data;
	76
	77	swsusp_free();
	78	data = filp->private_data;
	79	free_all_swap_pages(data->swap, data->bitmap);
	80	free_bitmap(data->bitmap);
	81	if (data->frozen) {
a6d70980	82	mutex_lock(&pm_mutex);
6e1819d6 RW	83	thaw_processes();
6e1819d6 RW	84	enable_nonboot_cpus();
a6d70980	85	mutex_unlock(&pm_mutex);
6e1819d6 RW	86	}
	87	atomic_inc(&device_available);
	88	return 0;
	89	}
	90
	91	static ssize_t snapshot_read(struct file filp, char __user buf,
	92	size_t count, loff_t *offp)
	93	{
	94	struct snapshot_data *data;
	95	ssize_t res;
	96
	97	data = filp->private_data;
	98	res = snapshot_read_next(&data->handle, count);
	99	if (res > 0) {
	100	if (copy_to_user(buf, data_of(data->handle), res))
	101	res = -EFAULT;
	102	else
	103	*offp = data->handle.offset;
	104	}
	105	return res;
	106	}
	107
	108	static ssize_t snapshot_write(struct file filp, const char __user buf,
	109	size_t count, loff_t *offp)
	110	{
	111	struct snapshot_data *data;
	112	ssize_t res;
	113
	114	data = filp->private_data;
	115	res = snapshot_write_next(&data->handle, count);
	116	if (res > 0) {
	117	if (copy_from_user(data_of(data->handle), buf, res))
	118	res = -EFAULT;
	119	else
	120	*offp = data->handle.offset;
	121	}
	122	return res;
	123	}
	124
d12c610e	125	static int snapshot_suspend(void)
25913052 RW	126	{
	127	int error;
	128
	129	mutex_lock(&pm_mutex);
	130	/* Free memory before shutting down devices. */
	131	error = swsusp_shrink_memory();
	132	if (error)
	133	goto Finish;
	134
	135	suspend_console();
	136	error = device_suspend(PMSG_FREEZE);
	137	if (error)
	138	goto Resume_devices;
	139
	140	error = disable_nonboot_cpus();
	141	if (!error) {
	142	in_suspend = 1;
	143	error = swsusp_suspend();
	144	}
	145	enable_nonboot_cpus();
	146	Resume_devices:
	147	device_resume();
	148	resume_console();
	149	Finish:
	150	mutex_unlock(&pm_mutex);
	151	return error;
	152	}
	153
d12c610e	154	static int snapshot_restore(void)
25913052 RW	155	{
	156	int error;
	157
	158	mutex_lock(&pm_mutex);
	159	pm_prepare_console();
	160	suspend_console();
	161	error = device_suspend(PMSG_PRETHAW);
	162	if (error)
	163	goto Resume_devices;
	164
	165	error = disable_nonboot_cpus();
	166	if (!error)
	167	error = swsusp_resume();
	168
	169	enable_nonboot_cpus();
	170	Resume_devices:
	171	device_resume();
	172	resume_console();
	173	pm_restore_console();
	174	mutex_unlock(&pm_mutex);
	175	return error;
	176	}
	177
6e1819d6 RW	178	static int snapshot_ioctl(struct inode inode, struct file filp,
	179	unsigned int cmd, unsigned long arg)
	180	{
	181	int error = 0;
	182	struct snapshot_data *data;
3aef83e0 RW	183	loff_t avail;
3aef83e0 RW	184	sector_t offset;
6e1819d6 RW	185
	186	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
	187	return -ENOTTY;
	188	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
	189	return -ENOTTY;
	190	if (!capable(CAP_SYS_ADMIN))
	191	return -EPERM;
	192
	193	data = filp->private_data;
	194
	195	switch (cmd) {
	196
	197	case SNAPSHOT_FREEZE:
	198	if (data->frozen)
	199	break;
a6d70980	200	mutex_lock(&pm_mutex);
25913052 RW	201	if (freeze_processes()) {
	202	thaw_processes();
	203	error = -EBUSY;
6e1819d6	204	}
a6d70980	205	mutex_unlock(&pm_mutex);
6e1819d6 RW	206	if (!error)
	207	data->frozen = 1;
	208	break;
	209
	210	case SNAPSHOT_UNFREEZE:
	211	if (!data->frozen)
	212	break;
a6d70980	213	mutex_lock(&pm_mutex);
6e1819d6	214	thaw_processes();
a6d70980	215	mutex_unlock(&pm_mutex);
6e1819d6 RW	216	data->frozen = 0;
	217	break;
	218
	219	case SNAPSHOT_ATOMIC_SNAPSHOT:
	220	if (data->mode != O_RDONLY \|\| !data->frozen \|\| data->ready) {
	221	error = -EPERM;
	222	break;
	223	}
25913052	224	error = snapshot_suspend();
6e1819d6 RW	225	if (!error)
	226	error = put_user(in_suspend, (unsigned int __user *)arg);
	227	if (!error)
	228	data->ready = 1;
	229	break;
	230
	231	case SNAPSHOT_ATOMIC_RESTORE:
8357376d	232	snapshot_write_finalize(&data->handle);
6e1819d6 RW	233	if (data->mode != O_WRONLY \|\| !data->frozen \|\|
	234	!snapshot_image_loaded(&data->handle)) {
	235	error = -EPERM;
	236	break;
	237	}
25913052	238	error = snapshot_restore();
6e1819d6 RW	239	break;
	240
	241	case SNAPSHOT_FREE:
	242	swsusp_free();
	243	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	244	data->ready = 0;
	245	break;
	246
	247	case SNAPSHOT_SET_IMAGE_SIZE:
	248	image_size = arg;
	249	break;
	250
	251	case SNAPSHOT_AVAIL_SWAP:
	252	avail = count_swap_pages(data->swap, 1);
	253	avail <<= PAGE_SHIFT;
	254	error = put_user(avail, (loff_t __user *)arg);
	255	break;
	256
	257	case SNAPSHOT_GET_SWAP_PAGE:
	258	if (data->swap < 0 \|\| data->swap >= MAX_SWAPFILES) {
	259	error = -ENODEV;
	260	break;
	261	}
	262	if (!data->bitmap) {
	263	data->bitmap = alloc_bitmap(count_swap_pages(data->swap, 0));
	264	if (!data->bitmap) {
	265	error = -ENOMEM;
	266	break;
	267	}
	268	}
3aef83e0	269	offset = alloc_swapdev_block(data->swap, data->bitmap);
6e1819d6 RW	270	if (offset) {
6e1819d6 RW	271	offset <<= PAGE_SHIFT;
3aef83e0	272	error = put_user(offset, (sector_t __user *)arg);
6e1819d6 RW	273	} else {
	274	error = -ENOSPC;
	275	}
	276	break;
	277
	278	case SNAPSHOT_FREE_SWAP_PAGES:
	279	if (data->swap < 0 \|\| data->swap >= MAX_SWAPFILES) {
	280	error = -ENODEV;
	281	break;
	282	}
	283	free_all_swap_pages(data->swap, data->bitmap);
	284	free_bitmap(data->bitmap);
	285	data->bitmap = NULL;
	286	break;
	287
	288	case SNAPSHOT_SET_SWAP_FILE:
	289	if (!data->bitmap) {
	290	/*
	291	* User space encodes device types as two-byte values,
	292	* so we need to recode them
	293	*/
	294	if (old_decode_dev(arg)) {
7bf23687 RW	295	data->swap = swap_type_of(old_decode_dev(arg),
7bf23687 RW	296	0, NULL);
6e1819d6 RW	297	if (data->swap < 0)
	298	error = -ENODEV;
	299	} else {
	300	data->swap = -1;
	301	error = -EINVAL;
	302	}
	303	} else {
	304	error = -EPERM;
	305	}
	306	break;
	307
9b238205 LT	308	case SNAPSHOT_S2RAM:
	309	if (!data->frozen) {
	310	error = -EPERM;
	311	break;
	312	}
	313
a6d70980	314	if (!mutex_trylock(&pm_mutex)) {
9b238205 LT	315	error = -EBUSY;
	316	break;
	317	}
	318
	319	if (pm_ops->prepare) {
	320	error = pm_ops->prepare(PM_SUSPEND_MEM);
	321	if (error)
	322	goto OutS3;
	323	}
	324
	325	/* Put devices to sleep */
97c7801c	326	suspend_console();
9b238205 LT	327	error = device_suspend(PMSG_SUSPEND);
	328	if (error) {
	329	printk(KERN_ERR "Failed to suspend some devices.\n");
	330	} else {
	331	/* Enter S3, system is already frozen */
	332	suspend_enter(PM_SUSPEND_MEM);
	333
	334	/* Wake up devices */
	335	device_resume();
	336	}
97c7801c	337	resume_console();
9b238205 LT	338	if (pm_ops->finish)
	339	pm_ops->finish(PM_SUSPEND_MEM);
	340
59a49335	341	OutS3:
a6d70980	342	mutex_unlock(&pm_mutex);
9b238205 LT	343	break;
9b238205 LT	344
3592695c SS	345	case SNAPSHOT_PMOPS:
	346	switch (arg) {
	347
	348	case PMOPS_PREPARE:
	349	if (pm_ops->prepare) {
	350	error = pm_ops->prepare(PM_SUSPEND_DISK);
	351	}
	352	break;
	353
	354	case PMOPS_ENTER:
	355	kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
	356	error = pm_ops->enter(PM_SUSPEND_DISK);
	357	break;
	358
	359	case PMOPS_FINISH:
	360	if (pm_ops && pm_ops->finish) {
	361	pm_ops->finish(PM_SUSPEND_DISK);
	362	}
	363	break;
	364
	365	default:
	366	printk(KERN_ERR "SNAPSHOT_PMOPS: invalid argument %ld\n", arg);
	367	error = -EINVAL;
	368
	369	}
	370	break;
	371
37b2ba12 RW	372	case SNAPSHOT_SET_SWAP_AREA:
	373	if (data->bitmap) {
	374	error = -EPERM;
	375	} else {
	376	struct resume_swap_area swap_area;
	377	dev_t swdev;
	378
	379	error = copy_from_user(&swap_area, (void __user *)arg,
	380	sizeof(struct resume_swap_area));
	381	if (error) {
	382	error = -EFAULT;
	383	break;
	384	}
	385
	386	/*
	387	* User space encodes device types as two-byte values,
	388	* so we need to recode them
	389	*/
	390	swdev = old_decode_dev(swap_area.dev);
	391	if (swdev) {
	392	offset = swap_area.offset;
7bf23687	393	data->swap = swap_type_of(swdev, offset, NULL);
37b2ba12 RW	394	if (data->swap < 0)
	395	error = -ENODEV;
	396	} else {
	397	data->swap = -1;
	398	error = -EINVAL;
	399	}
	400	}
	401	break;
	402
6e1819d6 RW	403	default:
	404	error = -ENOTTY;
	405
	406	}
	407
	408	return error;
	409	}
	410
15ad7cdc	411	static const struct file_operations snapshot_fops = {
6e1819d6 RW	412	.open = snapshot_open,
	413	.release = snapshot_release,
	414	.read = snapshot_read,
	415	.write = snapshot_write,
	416	.llseek = no_llseek,
	417	.ioctl = snapshot_ioctl,
	418	};
	419
	420	static struct miscdevice snapshot_device = {
	421	.minor = SNAPSHOT_MINOR,
	422	.name = "snapshot",
	423	.fops = &snapshot_fops,
	424	};
	425
	426	static int __init snapshot_device_init(void)
	427	{
	428	return misc_register(&snapshot_device);
	429	};
	430
	431	device_initcall(snapshot_device_init);