[deliverable/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 <rjw@sisk.pl>
 *
 * 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"

/*
 * NOTE: The SNAPSHOT_SET_SWAP_FILE and SNAPSHOT_PMOPS ioctls are obsolete and
 * will be removed in the future.  They are only preserved here for
 * compatibility with existing userland utilities.
 */
#define SNAPSHOT_SET_SWAP_FILE	_IOW(SNAPSHOT_IOC_MAGIC, 10, unsigned int)
#define SNAPSHOT_PMOPS		_IOW(SNAPSHOT_IOC_MAGIC, 12, unsigned int)

#define PMOPS_PREPARE	1
#define PMOPS_ENTER	2
#define PMOPS_FINISH	3


#define SNAPSHOT_MINOR	231

static struct snapshot_data {
	struct snapshot_handle handle;
	int swap;
	int mode;
	char frozen;
	char ready;
	char platform_support;
} snapshot_state;

atomic_t snapshot_device_available = ATOMIC_INIT(1);

static int snapshot_open(struct inode *inode, struct file *filp)
{
	struct snapshot_data *data;

	if (!atomic_add_unless(&snapshot_device_available, -1, 0))
		return -EBUSY;

	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
		atomic_inc(&snapshot_device_available);
		return -ENOSYS;
	}
	if(create_basic_memory_bitmaps()) {
		atomic_inc(&snapshot_device_available);
		return -ENOMEM;
	}
	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->frozen = 0;
	data->ready = 0;
	data->platform_support = 0;

	return 0;
}

static int snapshot_release(struct inode *inode, struct file *filp)
{
	struct snapshot_data *data;

	swsusp_free();
	free_basic_memory_bitmaps();
	data = filp->private_data;
	free_all_swap_pages(data->swap);
	if (data->frozen) {
		mutex_lock(&pm_mutex);
		thaw_processes();
		mutex_unlock(&pm_mutex);
	}
	atomic_inc(&snapshot_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;
	if (!data->ready)
		return -ENODATA;
	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 size;
	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);
		error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
		if (!error) {
			printk("Syncing filesystems ... ");
			sys_sync();
			printk("done.\n");

			error = freeze_processes();
			if (error)
				thaw_processes();
		}
		if (error)
			pm_notifier_call_chain(PM_POST_HIBERNATION);
		mutex_unlock(&pm_mutex);
		if (!error)
			data->frozen = 1;
		break;

	case SNAPSHOT_UNFREEZE:
		if (!data->frozen || data->ready)
			break;
		mutex_lock(&pm_mutex);
		thaw_processes();
		pm_notifier_call_chain(PM_POST_HIBERNATION);
		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 = hibernation_snapshot(data->platform_support);
		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 = hibernation_restore(data->platform_support);
		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_GET_IMAGE_SIZE:
		if (!data->ready) {
			error = -ENODATA;
			break;
		}
		size = snapshot_get_image_size();
		size <<= PAGE_SHIFT;
		error = put_user(size, (loff_t __user *)arg);
		break;

	case SNAPSHOT_AVAIL_SWAP:
		size = count_swap_pages(data->swap, 1);
		size <<= PAGE_SHIFT;
		error = put_user(size, (loff_t __user *)arg);
		break;

	case SNAPSHOT_GET_SWAP_PAGE:
		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
			error = -ENODEV;
			break;
		}
		offset = alloc_swapdev_block(data->swap);
		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);
		break;

	case SNAPSHOT_SET_SWAP_FILE: /* This ioctl is deprecated */
		if (!swsusp_swap_in_use()) {
			/*
			 * 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;
		}
		/*
		 * Tasks are frozen and the notifiers have been called with
		 * PM_HIBERNATION_PREPARE
		 */
		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
		mutex_unlock(&pm_mutex);
		break;

	case SNAPSHOT_PLATFORM_SUPPORT:
		data->platform_support = !!arg;
		break;

	case SNAPSHOT_POWER_OFF:
		if (data->platform_support)
			error = hibernation_platform_enter();
		break;

	case SNAPSHOT_PMOPS: /* This ioctl is deprecated */
		error = -EINVAL;

		switch (arg) {

		case PMOPS_PREPARE:
			data->platform_support = 1;
			error = 0;
			break;

		case PMOPS_ENTER:
			if (data->platform_support)
				error = hibernation_platform_enter();
			break;

		case PMOPS_FINISH:
			if (data->platform_support)
				error = 0;
			break;

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

		}
		break;

	case SNAPSHOT_SET_SWAP_AREA:
		if (swsusp_swap_in_use()) {
			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 <rjw@sisk.pl>
	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
eb57c1cf	31	/*
96f73749 RW	32	* NOTE: The SNAPSHOT_SET_SWAP_FILE and SNAPSHOT_PMOPS ioctls are obsolete and
	33	* will be removed in the future. They are only preserved here for
	34	* compatibility with existing userland utilities.
eb57c1cf	35	*/
96f73749	36	#define SNAPSHOT_SET_SWAP_FILE _IOW(SNAPSHOT_IOC_MAGIC, 10, unsigned int)
eb57c1cf RW	37	#define SNAPSHOT_PMOPS _IOW(SNAPSHOT_IOC_MAGIC, 12, unsigned int)
	38
	39	#define PMOPS_PREPARE 1
	40	#define PMOPS_ENTER 2
	41	#define PMOPS_FINISH 3
	42
	43
6e1819d6 RW	44	#define SNAPSHOT_MINOR 231
	45
	46	static struct snapshot_data {
	47	struct snapshot_handle handle;
	48	int swap;
6e1819d6 RW	49	int mode;
	50	char frozen;
	51	char ready;
eb57c1cf	52	char platform_support;
6e1819d6 RW	53	} snapshot_state;
6e1819d6 RW	54
0709db60	55	atomic_t snapshot_device_available = ATOMIC_INIT(1);
6e1819d6 RW	56
	57	static int snapshot_open(struct inode inode, struct file filp)
	58	{
	59	struct snapshot_data *data;
	60
0709db60	61	if (!atomic_add_unless(&snapshot_device_available, -1, 0))
6e1819d6 RW	62	return -EBUSY;
6e1819d6 RW	63
1525a2ad	64	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
0709db60	65	atomic_inc(&snapshot_device_available);
6e1819d6	66	return -ENOSYS;
1525a2ad RW	67	}
1525a2ad RW	68	if(create_basic_memory_bitmaps()) {
0709db60	69	atomic_inc(&snapshot_device_available);
74dfd666	70	return -ENOMEM;
1525a2ad	71	}
6e1819d6 RW	72	nonseekable_open(inode, filp);
	73	data = &snapshot_state;
	74	filp->private_data = data;
	75	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	76	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
915bae9e	77	data->swap = swsusp_resume_device ?
7bf23687	78	swap_type_of(swsusp_resume_device, 0, NULL) : -1;
6e1819d6 RW	79	data->mode = O_RDONLY;
	80	} else {
	81	data->swap = -1;
	82	data->mode = O_WRONLY;
	83	}
6e1819d6 RW	84	data->frozen = 0;
6e1819d6 RW	85	data->ready = 0;
eb57c1cf	86	data->platform_support = 0;
6e1819d6 RW	87
	88	return 0;
	89	}
	90
	91	static int snapshot_release(struct inode inode, struct file filp)
	92	{
	93	struct snapshot_data *data;
	94
	95	swsusp_free();
74dfd666	96	free_basic_memory_bitmaps();
6e1819d6	97	data = filp->private_data;
d1d241cc	98	free_all_swap_pages(data->swap);
6e1819d6	99	if (data->frozen) {
a6d70980	100	mutex_lock(&pm_mutex);
6e1819d6	101	thaw_processes();
a6d70980	102	mutex_unlock(&pm_mutex);
6e1819d6	103	}
0709db60	104	atomic_inc(&snapshot_device_available);
6e1819d6 RW	105	return 0;
	106	}
	107
	108	static ssize_t snapshot_read(struct file filp, 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;
2f41dddb RW	115	if (!data->ready)
2f41dddb RW	116	return -ENODATA;
6e1819d6 RW	117	res = snapshot_read_next(&data->handle, count);
	118	if (res > 0) {
	119	if (copy_to_user(buf, data_of(data->handle), res))
	120	res = -EFAULT;
	121	else
	122	*offp = data->handle.offset;
	123	}
	124	return res;
	125	}
	126
	127	static ssize_t snapshot_write(struct file filp, const char __user buf,
	128	size_t count, loff_t *offp)
	129	{
	130	struct snapshot_data *data;
	131	ssize_t res;
	132
	133	data = filp->private_data;
	134	res = snapshot_write_next(&data->handle, count);
	135	if (res > 0) {
	136	if (copy_from_user(data_of(data->handle), buf, res))
	137	res = -EFAULT;
	138	else
	139	*offp = data->handle.offset;
	140	}
	141	return res;
	142	}
	143
	144	static int snapshot_ioctl(struct inode inode, struct file filp,
	145	unsigned int cmd, unsigned long arg)
	146	{
	147	int error = 0;
	148	struct snapshot_data *data;
af508b34	149	loff_t size;
3aef83e0	150	sector_t offset;
6e1819d6 RW	151
	152	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
	153	return -ENOTTY;
	154	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
	155	return -ENOTTY;
	156	if (!capable(CAP_SYS_ADMIN))
	157	return -EPERM;
	158
	159	data = filp->private_data;
	160
	161	switch (cmd) {
	162
	163	case SNAPSHOT_FREEZE:
	164	if (data->frozen)
	165	break;
a6d70980	166	mutex_lock(&pm_mutex);
b10d9117 RW	167	error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
b10d9117 RW	168	if (!error) {
232b1432 RW	169	printk("Syncing filesystems ... ");
	170	sys_sync();
	171	printk("done.\n");
	172
b10d9117 RW	173	error = freeze_processes();
	174	if (error)
	175	thaw_processes();
6e1819d6	176	}
b10d9117 RW	177	if (error)
b10d9117 RW	178	pm_notifier_call_chain(PM_POST_HIBERNATION);
a6d70980	179	mutex_unlock(&pm_mutex);
6e1819d6 RW	180	if (!error)
	181	data->frozen = 1;
	182	break;
	183
	184	case SNAPSHOT_UNFREEZE:
2f41dddb	185	if (!data->frozen \|\| data->ready)
6e1819d6	186	break;
a6d70980	187	mutex_lock(&pm_mutex);
6e1819d6	188	thaw_processes();
b10d9117	189	pm_notifier_call_chain(PM_POST_HIBERNATION);
a6d70980	190	mutex_unlock(&pm_mutex);
6e1819d6 RW	191	data->frozen = 0;
	192	break;
	193
	194	case SNAPSHOT_ATOMIC_SNAPSHOT:
	195	if (data->mode != O_RDONLY \|\| !data->frozen \|\| data->ready) {
	196	error = -EPERM;
	197	break;
	198	}
eb57c1cf	199	error = hibernation_snapshot(data->platform_support);
6e1819d6 RW	200	if (!error)
	201	error = put_user(in_suspend, (unsigned int __user *)arg);
	202	if (!error)
	203	data->ready = 1;
	204	break;
	205
	206	case SNAPSHOT_ATOMIC_RESTORE:
8357376d	207	snapshot_write_finalize(&data->handle);
6e1819d6 RW	208	if (data->mode != O_WRONLY \|\| !data->frozen \|\|
	209	!snapshot_image_loaded(&data->handle)) {
	210	error = -EPERM;
	211	break;
	212	}
eb57c1cf	213	error = hibernation_restore(data->platform_support);
6e1819d6 RW	214	break;
	215
	216	case SNAPSHOT_FREE:
	217	swsusp_free();
	218	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	219	data->ready = 0;
	220	break;
	221
	222	case SNAPSHOT_SET_IMAGE_SIZE:
	223	image_size = arg;
	224	break;
	225
af508b34 RW	226	case SNAPSHOT_GET_IMAGE_SIZE:
	227	if (!data->ready) {
	228	error = -ENODATA;
	229	break;
	230	}
	231	size = snapshot_get_image_size();
	232	size <<= PAGE_SHIFT;
	233	error = put_user(size, (loff_t __user *)arg);
	234	break;
	235
6e1819d6	236	case SNAPSHOT_AVAIL_SWAP:
af508b34 RW	237	size = count_swap_pages(data->swap, 1);
	238	size <<= PAGE_SHIFT;
	239	error = put_user(size, (loff_t __user *)arg);
6e1819d6 RW	240	break;
	241
	242	case SNAPSHOT_GET_SWAP_PAGE:
	243	if (data->swap < 0 \|\| data->swap >= MAX_SWAPFILES) {
	244	error = -ENODEV;
	245	break;
	246	}
d1d241cc	247	offset = alloc_swapdev_block(data->swap);
6e1819d6 RW	248	if (offset) {
6e1819d6 RW	249	offset <<= PAGE_SHIFT;
3aef83e0	250	error = put_user(offset, (sector_t __user *)arg);
6e1819d6 RW	251	} else {
	252	error = -ENOSPC;
	253	}
	254	break;
	255
	256	case SNAPSHOT_FREE_SWAP_PAGES:
	257	if (data->swap < 0 \|\| data->swap >= MAX_SWAPFILES) {
	258	error = -ENODEV;
	259	break;
	260	}
d1d241cc	261	free_all_swap_pages(data->swap);
6e1819d6 RW	262	break;
6e1819d6 RW	263
96f73749	264	case SNAPSHOT_SET_SWAP_FILE: /* This ioctl is deprecated */
d1d241cc	265	if (!swsusp_swap_in_use()) {
6e1819d6 RW	266	/*
	267	* User space encodes device types as two-byte values,
	268	* so we need to recode them
	269	*/
	270	if (old_decode_dev(arg)) {
7bf23687 RW	271	data->swap = swap_type_of(old_decode_dev(arg),
7bf23687 RW	272	0, NULL);
6e1819d6 RW	273	if (data->swap < 0)
	274	error = -ENODEV;
	275	} else {
	276	data->swap = -1;
	277	error = -EINVAL;
	278	}
	279	} else {
	280	error = -EPERM;
	281	}
	282	break;
	283
9b238205 LT	284	case SNAPSHOT_S2RAM:
	285	if (!data->frozen) {
	286	error = -EPERM;
	287	break;
	288	}
a6d70980	289	if (!mutex_trylock(&pm_mutex)) {
9b238205 LT	290	error = -EBUSY;
	291	break;
	292	}
6c961dfb RW	293	/*
	294	* Tasks are frozen and the notifiers have been called with
	295	* PM_HIBERNATION_PREPARE
	296	*/
	297	error = suspend_devices_and_enter(PM_SUSPEND_MEM);
a6d70980	298	mutex_unlock(&pm_mutex);
9b238205 LT	299	break;
9b238205 LT	300
eb57c1cf RW	301	case SNAPSHOT_PLATFORM_SUPPORT:
	302	data->platform_support = !!arg;
	303	break;
	304
	305	case SNAPSHOT_POWER_OFF:
	306	if (data->platform_support)
	307	error = hibernation_platform_enter();
	308	break;
	309
	310	case SNAPSHOT_PMOPS: /* This ioctl is deprecated */
2b5b09b3 RW	311	error = -EINVAL;
2b5b09b3 RW	312
3592695c SS	313	switch (arg) {
	314
	315	case PMOPS_PREPARE:
eb57c1cf	316	data->platform_support = 1;
7777fab9	317	error = 0;
3592695c SS	318	break;
	319
	320	case PMOPS_ENTER:
eb57c1cf	321	if (data->platform_support)
7777fab9	322	error = hibernation_platform_enter();
3592695c SS	323	break;
	324
	325	case PMOPS_FINISH:
eb57c1cf	326	if (data->platform_support)
2b5b09b3	327	error = 0;
3592695c SS	328	break;
	329
	330	default:
	331	printk(KERN_ERR "SNAPSHOT_PMOPS: invalid argument %ld\n", arg);
3592695c SS	332
	333	}
	334	break;
	335
37b2ba12	336	case SNAPSHOT_SET_SWAP_AREA:
d1d241cc	337	if (swsusp_swap_in_use()) {
37b2ba12 RW	338	error = -EPERM;
	339	} else {
	340	struct resume_swap_area swap_area;
	341	dev_t swdev;
	342
	343	error = copy_from_user(&swap_area, (void __user *)arg,
	344	sizeof(struct resume_swap_area));
	345	if (error) {
	346	error = -EFAULT;
	347	break;
	348	}
	349
	350	/*
	351	* User space encodes device types as two-byte values,
	352	* so we need to recode them
	353	*/
	354	swdev = old_decode_dev(swap_area.dev);
	355	if (swdev) {
	356	offset = swap_area.offset;
7bf23687	357	data->swap = swap_type_of(swdev, offset, NULL);
37b2ba12 RW	358	if (data->swap < 0)
	359	error = -ENODEV;
	360	} else {
	361	data->swap = -1;
	362	error = -EINVAL;
	363	}
	364	}
	365	break;
	366
6e1819d6 RW	367	default:
	368	error = -ENOTTY;
	369
	370	}
	371
	372	return error;
	373	}
	374
15ad7cdc	375	static const struct file_operations snapshot_fops = {
6e1819d6 RW	376	.open = snapshot_open,
	377	.release = snapshot_release,
	378	.read = snapshot_read,
	379	.write = snapshot_write,
	380	.llseek = no_llseek,
	381	.ioctl = snapshot_ioctl,
	382	};
	383
	384	static struct miscdevice snapshot_device = {
	385	.minor = SNAPSHOT_MINOR,
	386	.name = "snapshot",
	387	.fops = &snapshot_fops,
	388	};
	389
	390	static int __init snapshot_device_init(void)
	391	{
	392	return misc_register(&snapshot_device);
	393	};
	394
	395	device_initcall(snapshot_device_init);