[net-next-2.6.git] / drivers / char / raw.c

/*
 * linux/drivers/char/raw.c
 *
 * Front-end raw character devices.  These can be bound to any block
 * devices to provide genuine Unix raw character device semantics.
 *
 * We reserve minor number 0 for a control interface.  ioctl()s on this
 * device are used to bind the other minor numbers to block devices.
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/raw.h>
#include <linux/capability.h>
#include <linux/uio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/smp_lock.h>
#include <linux/gfp.h>

#include <asm/uaccess.h>

struct raw_device_data {
	struct block_device *binding;
	int inuse;
};

static struct class *raw_class;
static struct raw_device_data raw_devices[MAX_RAW_MINORS];
static DEFINE_MUTEX(raw_mutex);
static const struct file_operations raw_ctl_fops; /* forward declaration */

/*
 * Open/close code for raw IO.
 *
 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
 * point at the blockdev's address_space and set the file handle to use
 * O_DIRECT.
 *
 * Set the device's soft blocksize to the minimum possible.  This gives the
 * finest possible alignment and has no adverse impact on performance.
 */
static int raw_open(struct inode *inode, struct file *filp)
{
	const int minor = iminor(inode);
	struct block_device *bdev;
	int err;

	if (minor == 0) {	/* It is the control device */
		filp->f_op = &raw_ctl_fops;
		return 0;
	}

	lock_kernel();
	mutex_lock(&raw_mutex);

	/*
	 * All we need to do on open is check that the device is bound.
	 */
	bdev = raw_devices[minor].binding;
	err = -ENODEV;
	if (!bdev)
		goto out;
	igrab(bdev->bd_inode);
	err = blkdev_get(bdev, filp->f_mode);
	if (err)
		goto out;
	err = bd_claim(bdev, raw_open);
	if (err)
		goto out1;
	err = set_blocksize(bdev, bdev_logical_block_size(bdev));
	if (err)
		goto out2;
	filp->f_flags |= O_DIRECT;
	filp->f_mapping = bdev->bd_inode->i_mapping;
	if (++raw_devices[minor].inuse == 1)
		filp->f_path.dentry->d_inode->i_mapping =
			bdev->bd_inode->i_mapping;
	filp->private_data = bdev;
	mutex_unlock(&raw_mutex);
	unlock_kernel();
	return 0;

out2:
	bd_release(bdev);
out1:
	blkdev_put(bdev, filp->f_mode);
out:
	mutex_unlock(&raw_mutex);
	unlock_kernel();
	return err;
}

/*
 * When the final fd which refers to this character-special node is closed, we
 * make its ->mapping point back at its own i_data.
 */
static int raw_release(struct inode *inode, struct file *filp)
{
	const int minor= iminor(inode);
	struct block_device *bdev;

	mutex_lock(&raw_mutex);
	bdev = raw_devices[minor].binding;
	if (--raw_devices[minor].inuse == 0) {
		/* Here  inode->i_mapping == bdev->bd_inode->i_mapping  */
		inode->i_mapping = &inode->i_data;
		inode->i_mapping->backing_dev_info = &default_backing_dev_info;
	}
	mutex_unlock(&raw_mutex);

	bd_release(bdev);
	blkdev_put(bdev, filp->f_mode);
	return 0;
}

/*
 * Forward ioctls to the underlying block device.
 */
static long
raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
{
	struct block_device *bdev = filp->private_data;
	int ret;

	lock_kernel();
	ret = blkdev_ioctl(bdev, 0, command, arg);
	unlock_kernel();

	return ret;
}

static void bind_device(struct raw_config_request *rq)
{
	device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL,
		      "raw%d", rq->raw_minor);
}

/*
 * Deal with ioctls against the raw-device control interface, to bind
 * and unbind other raw devices.
 */
static long raw_ctl_ioctl(struct file *filp, unsigned int command,
			  unsigned long arg)
{
	struct raw_config_request rq;
	struct raw_device_data *rawdev;
	int err = 0;

	lock_kernel();
	switch (command) {
	case RAW_SETBIND:
	case RAW_GETBIND:

		/* First, find out which raw minor we want */

		if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
			err = -EFAULT;
			goto out;
		}

		if (rq.raw_minor <= 0 || rq.raw_minor >= MAX_RAW_MINORS) {
			err = -EINVAL;
			goto out;
		}
		rawdev = &raw_devices[rq.raw_minor];

		if (command == RAW_SETBIND) {
			dev_t dev;

			/*
			 * This is like making block devices, so demand the
			 * same capability
			 */
			if (!capable(CAP_SYS_ADMIN)) {
				err = -EPERM;
				goto out;
			}

			/*
			 * For now, we don't need to check that the underlying
			 * block device is present or not: we can do that when
			 * the raw device is opened.  Just check that the
			 * major/minor numbers make sense.
			 */

			dev = MKDEV(rq.block_major, rq.block_minor);
			if ((rq.block_major == 0 && rq.block_minor != 0) ||
					MAJOR(dev) != rq.block_major ||
					MINOR(dev) != rq.block_minor) {
				err = -EINVAL;
				goto out;
			}

			mutex_lock(&raw_mutex);
			if (rawdev->inuse) {
				mutex_unlock(&raw_mutex);
				err = -EBUSY;
				goto out;
			}
			if (rawdev->binding) {
				bdput(rawdev->binding);
				module_put(THIS_MODULE);
			}
			if (rq.block_major == 0 && rq.block_minor == 0) {
				/* unbind */
				rawdev->binding = NULL;
				device_destroy(raw_class,
						MKDEV(RAW_MAJOR, rq.raw_minor));
			} else {
				rawdev->binding = bdget(dev);
				if (rawdev->binding == NULL)
					err = -ENOMEM;
				else {
					__module_get(THIS_MODULE);
					bind_device(&rq);
				}
			}
			mutex_unlock(&raw_mutex);
		} else {
			struct block_device *bdev;

			mutex_lock(&raw_mutex);
			bdev = rawdev->binding;
			if (bdev) {
				rq.block_major = MAJOR(bdev->bd_dev);
				rq.block_minor = MINOR(bdev->bd_dev);
			} else {
				rq.block_major = rq.block_minor = 0;
			}
			mutex_unlock(&raw_mutex);
			if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
				err = -EFAULT;
				goto out;
			}
		}
		break;
	default:
		err = -EINVAL;
		break;
	}
out:
	unlock_kernel();
	return err;
}

static const struct file_operations raw_fops = {
	.read		= do_sync_read,
	.aio_read	= generic_file_aio_read,
	.write		= do_sync_write,
	.aio_write	= blkdev_aio_write,
	.fsync		= blkdev_fsync,
	.open		= raw_open,
	.release	= raw_release,
	.unlocked_ioctl = raw_ioctl,
	.owner		= THIS_MODULE,
};

static const struct file_operations raw_ctl_fops = {
	.unlocked_ioctl = raw_ctl_ioctl,
	.open		= raw_open,
	.owner		= THIS_MODULE,
};

static struct cdev raw_cdev;

static char *raw_devnode(struct device *dev, mode_t *mode)
{
	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
}

static int __init raw_init(void)
{
	dev_t dev = MKDEV(RAW_MAJOR, 0);
	int ret;

	ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
	if (ret)
		goto error;

	cdev_init(&raw_cdev, &raw_fops);
	ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
	if (ret) {
		kobject_put(&raw_cdev.kobj);
		goto error_region;
	}

	raw_class = class_create(THIS_MODULE, "raw");
	if (IS_ERR(raw_class)) {
		printk(KERN_ERR "Error creating raw class.\n");
		cdev_del(&raw_cdev);
		ret = PTR_ERR(raw_class);
		goto error_region;
	}
	raw_class->devnode = raw_devnode;
	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");

	return 0;

error_region:
	unregister_chrdev_region(dev, MAX_RAW_MINORS);
error:
	return ret;
}

static void __exit raw_exit(void)
{
	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
	class_destroy(raw_class);
	cdev_del(&raw_cdev);
	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
}

module_init(raw_init);
module_exit(raw_exit);
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/drivers/char/raw.c
	3	*
	4	* Front-end raw character devices. These can be bound to any block
	5	* devices to provide genuine Unix raw character device semantics.
	6	*
	7	* We reserve minor number 0 for a control interface. ioctl()s on this
	8	* device are used to bind the other minor numbers to block devices.
	9	*/
	10
	11	#include <linux/init.h>
	12	#include <linux/fs.h>
1da177e4 LT	13	#include <linux/major.h>
	14	#include <linux/blkdev.h>
	15	#include <linux/module.h>
	16	#include <linux/raw.h>
	17	#include <linux/capability.h>
	18	#include <linux/uio.h>
	19	#include <linux/cdev.h>
	20	#include <linux/device.h>
8ed965d6	21	#include <linux/mutex.h>
c0bed680	22	#include <linux/smp_lock.h>
5a0e3ad6	23	#include <linux/gfp.h>
1da177e4 LT	24
	25	#include <asm/uaccess.h>
	26
	27	struct raw_device_data {
	28	struct block_device *binding;
	29	int inuse;
	30	};
	31
ca8eca68	32	static struct class *raw_class;
1da177e4	33	static struct raw_device_data raw_devices[MAX_RAW_MINORS];
8ed965d6	34	static DEFINE_MUTEX(raw_mutex);
62322d25	35	static const struct file_operations raw_ctl_fops; /* forward declaration */
1da177e4 LT	36
	37	/*
	38	* Open/close code for raw IO.
	39	*
	40	* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
	41	* point at the blockdev's address_space and set the file handle to use
	42	* O_DIRECT.
	43	*
	44	* Set the device's soft blocksize to the minimum possible. This gives the
	45	* finest possible alignment and has no adverse impact on performance.
	46	*/
	47	static int raw_open(struct inode inode, struct file filp)
	48	{
	49	const int minor = iminor(inode);
	50	struct block_device *bdev;
	51	int err;
	52
	53	if (minor == 0) { /* It is the control device */
	54	filp->f_op = &raw_ctl_fops;
	55	return 0;
	56	}
	57
c0bed680	58	lock_kernel();
8ed965d6	59	mutex_lock(&raw_mutex);
1da177e4 LT	60
	61	/*
	62	* All we need to do on open is check that the device is bound.
	63	*/
	64	bdev = raw_devices[minor].binding;
	65	err = -ENODEV;
	66	if (!bdev)
	67	goto out;
	68	igrab(bdev->bd_inode);
572c4892	69	err = blkdev_get(bdev, filp->f_mode);
1da177e4 LT	70	if (err)
	71	goto out;
	72	err = bd_claim(bdev, raw_open);
	73	if (err)
	74	goto out1;
e1defc4f	75	err = set_blocksize(bdev, bdev_logical_block_size(bdev));
1da177e4 LT	76	if (err)
	77	goto out2;
	78	filp->f_flags \|= O_DIRECT;
	79	filp->f_mapping = bdev->bd_inode->i_mapping;
	80	if (++raw_devices[minor].inuse == 1)
a7113a96	81	filp->f_path.dentry->d_inode->i_mapping =
1da177e4 LT	82	bdev->bd_inode->i_mapping;
1da177e4 LT	83	filp->private_data = bdev;
8ed965d6	84	mutex_unlock(&raw_mutex);
c0bed680	85	unlock_kernel();
1da177e4 LT	86	return 0;
	87
	88	out2:
	89	bd_release(bdev);
	90	out1:
9a1c3542	91	blkdev_put(bdev, filp->f_mode);
1da177e4	92	out:
8ed965d6	93	mutex_unlock(&raw_mutex);
996ff68d	94	unlock_kernel();
1da177e4 LT	95	return err;
	96	}
	97
	98	/*
	99	* When the final fd which refers to this character-special node is closed, we
	100	* make its ->mapping point back at its own i_data.
	101	*/
	102	static int raw_release(struct inode inode, struct file filp)
	103	{
	104	const int minor= iminor(inode);
	105	struct block_device *bdev;
	106
8ed965d6	107	mutex_lock(&raw_mutex);
1da177e4 LT	108	bdev = raw_devices[minor].binding;
	109	if (--raw_devices[minor].inuse == 0) {
	110	/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
	111	inode->i_mapping = &inode->i_data;
	112	inode->i_mapping->backing_dev_info = &default_backing_dev_info;
	113	}
8ed965d6	114	mutex_unlock(&raw_mutex);
1da177e4 LT	115
1da177e4 LT	116	bd_release(bdev);
9a1c3542	117	blkdev_put(bdev, filp->f_mode);
1da177e4 LT	118	return 0;
	119	}
	120
	121	/*
	122	* Forward ioctls to the underlying block device.
	123	*/
55929332 AB	124	static long
55929332 AB	125	raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
1da177e4 LT	126	{
1da177e4 LT	127	struct block_device *bdev = filp->private_data;
55929332	128	int ret;
1da177e4	129
55929332 AB	130	lock_kernel();
	131	ret = blkdev_ioctl(bdev, 0, command, arg);
	132	unlock_kernel();
	133
	134	return ret;
1da177e4 LT	135	}
	136
	137	static void bind_device(struct raw_config_request *rq)
	138	{
38ca6c34	139	device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
03457cd4 GKH	140	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL,
03457cd4 GKH	141	"raw%d", rq->raw_minor);
1da177e4 LT	142	}
	143
	144	/*
	145	* Deal with ioctls against the raw-device control interface, to bind
	146	* and unbind other raw devices.
	147	*/
55929332 AB	148	static long raw_ctl_ioctl(struct file *filp, unsigned int command,
55929332 AB	149	unsigned long arg)
1da177e4 LT	150	{
	151	struct raw_config_request rq;
	152	struct raw_device_data *rawdev;
	153	int err = 0;
	154
55929332	155	lock_kernel();
1da177e4 LT	156	switch (command) {
	157	case RAW_SETBIND:
	158	case RAW_GETBIND:
	159
	160	/* First, find out which raw minor we want */
	161
	162	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
	163	err = -EFAULT;
	164	goto out;
	165	}
	166
38584c14	167	if (rq.raw_minor <= 0 \|\| rq.raw_minor >= MAX_RAW_MINORS) {
1da177e4 LT	168	err = -EINVAL;
	169	goto out;
	170	}
	171	rawdev = &raw_devices[rq.raw_minor];
	172
	173	if (command == RAW_SETBIND) {
	174	dev_t dev;
	175
	176	/*
	177	* This is like making block devices, so demand the
	178	* same capability
	179	*/
	180	if (!capable(CAP_SYS_ADMIN)) {
	181	err = -EPERM;
	182	goto out;
	183	}
	184
	185	/*
	186	* For now, we don't need to check that the underlying
	187	* block device is present or not: we can do that when
	188	* the raw device is opened. Just check that the
	189	* major/minor numbers make sense.
	190	*/
	191
	192	dev = MKDEV(rq.block_major, rq.block_minor);
	193	if ((rq.block_major == 0 && rq.block_minor != 0) \|\|
	194	MAJOR(dev) != rq.block_major \|\|
	195	MINOR(dev) != rq.block_minor) {
	196	err = -EINVAL;
	197	goto out;
	198	}
	199
8ed965d6	200	mutex_lock(&raw_mutex);
1da177e4	201	if (rawdev->inuse) {
8ed965d6	202	mutex_unlock(&raw_mutex);
1da177e4 LT	203	err = -EBUSY;
	204	goto out;
	205	}
	206	if (rawdev->binding) {
	207	bdput(rawdev->binding);
	208	module_put(THIS_MODULE);
	209	}
	210	if (rq.block_major == 0 && rq.block_minor == 0) {
	211	/* unbind */
	212	rawdev->binding = NULL;
38ca6c34	213	device_destroy(raw_class,
ca8eca68	214	MKDEV(RAW_MAJOR, rq.raw_minor));
1da177e4 LT	215	} else {
	216	rawdev->binding = bdget(dev);
	217	if (rawdev->binding == NULL)
	218	err = -ENOMEM;
	219	else {
	220	__module_get(THIS_MODULE);
	221	bind_device(&rq);
	222	}
	223	}
8ed965d6	224	mutex_unlock(&raw_mutex);
1da177e4 LT	225	} else {
	226	struct block_device *bdev;
	227
8ed965d6	228	mutex_lock(&raw_mutex);
1da177e4 LT	229	bdev = rawdev->binding;
	230	if (bdev) {
	231	rq.block_major = MAJOR(bdev->bd_dev);
	232	rq.block_minor = MINOR(bdev->bd_dev);
	233	} else {
	234	rq.block_major = rq.block_minor = 0;
	235	}
8ed965d6	236	mutex_unlock(&raw_mutex);
1da177e4 LT	237	if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
	238	err = -EFAULT;
	239	goto out;
	240	}
	241	}
	242	break;
	243	default:
	244	err = -EINVAL;
	245	break;
	246	}
	247	out:
55929332	248	unlock_kernel();
1da177e4 LT	249	return err;
	250	}
	251
62322d25	252	static const struct file_operations raw_fops = {
55929332 AB	253	.read = do_sync_read,
	254	.aio_read = generic_file_aio_read,
	255	.write = do_sync_write,
	256	.aio_write = blkdev_aio_write,
	257	.fsync = blkdev_fsync,
	258	.open = raw_open,
	259	.release = raw_release,
	260	.unlocked_ioctl = raw_ioctl,
	261	.owner = THIS_MODULE,
1da177e4 LT	262	};
1da177e4 LT	263
62322d25	264	static const struct file_operations raw_ctl_fops = {
55929332 AB	265	.unlocked_ioctl = raw_ctl_ioctl,
	266	.open = raw_open,
	267	.owner = THIS_MODULE,
1da177e4 LT	268	};
1da177e4 LT	269
7e7654a9	270	static struct cdev raw_cdev;
1da177e4	271
e454cea2	272	static char raw_devnode(struct device dev, mode_t *mode)
6fd46933 KS	273	{
	274	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
	275	}
	276
1da177e4 LT	277	static int __init raw_init(void)
1da177e4 LT	278	{
1da177e4	279	dev_t dev = MKDEV(RAW_MAJOR, 0);
3e26a423	280	int ret;
1da177e4	281
3e26a423 REB	282	ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
3e26a423 REB	283	if (ret)
1da177e4 LT	284	goto error;
	285
	286	cdev_init(&raw_cdev, &raw_fops);
3e26a423 REB	287	ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
3e26a423 REB	288	if (ret) {
1da177e4	289	kobject_put(&raw_cdev.kobj);
3e26a423	290	goto error_region;
1da177e4 LT	291	}
1da177e4 LT	292
ca8eca68	293	raw_class = class_create(THIS_MODULE, "raw");
1da177e4 LT	294	if (IS_ERR(raw_class)) {
	295	printk(KERN_ERR "Error creating raw class.\n");
	296	cdev_del(&raw_cdev);
3e26a423 REB	297	ret = PTR_ERR(raw_class);
3e26a423 REB	298	goto error_region;
1da177e4	299	}
e454cea2	300	raw_class->devnode = raw_devnode;
03457cd4	301	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
1da177e4	302
1da177e4 LT	303	return 0;
1da177e4 LT	304
3e26a423 REB	305	error_region:
3e26a423 REB	306	unregister_chrdev_region(dev, MAX_RAW_MINORS);
1da177e4	307	error:
3e26a423	308	return ret;
1da177e4 LT	309	}
	310
	311	static void __exit raw_exit(void)
	312	{
38ca6c34	313	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68	314	class_destroy(raw_class);
1da177e4 LT	315	cdev_del(&raw_cdev);
	316	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
	317	}
	318
	319	module_init(raw_init);
	320	module_exit(raw_exit);
	321	MODULE_LICENSE("GPL");