[deliverable/linux.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/devfs_fs_kernel.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 <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 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;
	}

	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, 0);
	if (err)
		goto out;
	err = bd_claim(bdev, raw_open);
	if (err)
		goto out1;
	err = set_blocksize(bdev, bdev_hardsect_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_dentry->d_inode->i_mapping =
			bdev->bd_inode->i_mapping;
	filp->private_data = bdev;
	mutex_unlock(&raw_mutex);
	return 0;

out2:
	bd_release(bdev);
out1:
	blkdev_put(bdev);
out:
	mutex_unlock(&raw_mutex);
	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);
	return 0;
}

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

	return blkdev_ioctl(bdev->bd_inode, NULL, command, arg);
}

static void bind_device(struct raw_config_request *rq)
{
	class_device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
	class_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 int raw_ctl_ioctl(struct inode *inode, struct file *filp,
			unsigned int command, unsigned long arg)
{
	struct raw_config_request rq;
	struct raw_device_data *rawdev;
	int err = 0;

	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;
				class_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:
	return err;
}

static ssize_t raw_file_write(struct file *file, const char __user *buf,
				   size_t count, loff_t *ppos)
{
	struct iovec local_iov = {
		.iov_base = (char __user *)buf,
		.iov_len = count
	};

	return generic_file_write_nolock(file, &local_iov, 1, ppos);
}

static ssize_t raw_file_aio_write(struct kiocb *iocb, const char __user *buf,
					size_t count, loff_t pos)
{
	struct iovec local_iov = {
		.iov_base = (char __user *)buf,
		.iov_len = count
	};

	return generic_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
}


static struct file_operations raw_fops = {
	.read	=	generic_file_read,
	.aio_read = 	generic_file_aio_read,
	.write	=	raw_file_write,
	.aio_write = 	raw_file_aio_write,
	.open	=	raw_open,
	.release=	raw_release,
	.ioctl	=	raw_ioctl,
	.readv	= 	generic_file_readv,
	.writev	= 	generic_file_writev,
	.owner	=	THIS_MODULE,
};

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

static struct cdev raw_cdev = {
	.kobj	=	{.name = "raw", },
	.owner	=	THIS_MODULE,
};

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

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

	cdev_init(&raw_cdev, &raw_fops);
	if (cdev_add(&raw_cdev, dev, MAX_RAW_MINORS)) {
		kobject_put(&raw_cdev.kobj);
		unregister_chrdev_region(dev, MAX_RAW_MINORS);
		goto error;
	}

	raw_class = class_create(THIS_MODULE, "raw");
	if (IS_ERR(raw_class)) {
		printk(KERN_ERR "Error creating raw class.\n");
		cdev_del(&raw_cdev);
		unregister_chrdev_region(dev, MAX_RAW_MINORS);
		goto error;
	}
	class_device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");

	devfs_mk_cdev(MKDEV(RAW_MAJOR, 0),
		      S_IFCHR | S_IRUGO | S_IWUGO,
		      "raw/rawctl");
	for (i = 1; i < MAX_RAW_MINORS; i++)
		devfs_mk_cdev(MKDEV(RAW_MAJOR, i),
			      S_IFCHR | S_IRUGO | S_IWUGO,
			      "raw/raw%d", i);
	return 0;

error:
	printk(KERN_ERR "error register raw device\n");
	return 1;
}

static void __exit raw_exit(void)
{
	int i;

	for (i = 1; i < MAX_RAW_MINORS; i++)
		devfs_remove("raw/raw%d", i);
	devfs_remove("raw/rawctl");
	devfs_remove("raw");
	class_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>
	13	#include <linux/devfs_fs_kernel.h>
	14	#include <linux/major.h>
	15	#include <linux/blkdev.h>
	16	#include <linux/module.h>
	17	#include <linux/raw.h>
	18	#include <linux/capability.h>
	19	#include <linux/uio.h>
	20	#include <linux/cdev.h>
	21	#include <linux/device.h>
8ed965d6	22	#include <linux/mutex.h>
1da177e4 LT	23
	24	#include <asm/uaccess.h>
	25
	26	struct raw_device_data {
	27	struct block_device *binding;
	28	int inuse;
	29	};
	30
ca8eca68	31	static struct class *raw_class;
1da177e4	32	static struct raw_device_data raw_devices[MAX_RAW_MINORS];
8ed965d6	33	static DEFINE_MUTEX(raw_mutex);
1da177e4 LT	34	static struct file_operations raw_ctl_fops; /* forward declaration */
	35
	36	/*
	37	* Open/close code for raw IO.
	38	*
	39	* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
	40	* point at the blockdev's address_space and set the file handle to use
	41	* O_DIRECT.
	42	*
	43	* Set the device's soft blocksize to the minimum possible. This gives the
	44	* finest possible alignment and has no adverse impact on performance.
	45	*/
	46	static int raw_open(struct inode inode, struct file filp)
	47	{
	48	const int minor = iminor(inode);
	49	struct block_device *bdev;
	50	int err;
	51
	52	if (minor == 0) { /* It is the control device */
	53	filp->f_op = &raw_ctl_fops;
	54	return 0;
	55	}
	56
8ed965d6	57	mutex_lock(&raw_mutex);
1da177e4 LT	58
	59	/*
	60	* All we need to do on open is check that the device is bound.
	61	*/
	62	bdev = raw_devices[minor].binding;
	63	err = -ENODEV;
	64	if (!bdev)
	65	goto out;
	66	igrab(bdev->bd_inode);
	67	err = blkdev_get(bdev, filp->f_mode, 0);
	68	if (err)
	69	goto out;
	70	err = bd_claim(bdev, raw_open);
	71	if (err)
	72	goto out1;
	73	err = set_blocksize(bdev, bdev_hardsect_size(bdev));
	74	if (err)
	75	goto out2;
	76	filp->f_flags \|= O_DIRECT;
	77	filp->f_mapping = bdev->bd_inode->i_mapping;
	78	if (++raw_devices[minor].inuse == 1)
	79	filp->f_dentry->d_inode->i_mapping =
	80	bdev->bd_inode->i_mapping;
	81	filp->private_data = bdev;
8ed965d6	82	mutex_unlock(&raw_mutex);
1da177e4 LT	83	return 0;
	84
	85	out2:
	86	bd_release(bdev);
	87	out1:
	88	blkdev_put(bdev);
	89	out:
8ed965d6	90	mutex_unlock(&raw_mutex);
1da177e4 LT	91	return err;
	92	}
	93
	94	/*
	95	* When the final fd which refers to this character-special node is closed, we
	96	* make its ->mapping point back at its own i_data.
	97	*/
	98	static int raw_release(struct inode inode, struct file filp)
	99	{
	100	const int minor= iminor(inode);
	101	struct block_device *bdev;
	102
8ed965d6	103	mutex_lock(&raw_mutex);
1da177e4 LT	104	bdev = raw_devices[minor].binding;
	105	if (--raw_devices[minor].inuse == 0) {
	106	/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
	107	inode->i_mapping = &inode->i_data;
	108	inode->i_mapping->backing_dev_info = &default_backing_dev_info;
	109	}
8ed965d6	110	mutex_unlock(&raw_mutex);
1da177e4 LT	111
	112	bd_release(bdev);
	113	blkdev_put(bdev);
	114	return 0;
	115	}
	116
	117	/*
	118	* Forward ioctls to the underlying block device.
	119	*/
	120	static int
	121	raw_ioctl(struct inode inode, struct file filp,
	122	unsigned int command, unsigned long arg)
	123	{
	124	struct block_device *bdev = filp->private_data;
	125
e72022e1	126	return blkdev_ioctl(bdev->bd_inode, NULL, command, arg);
1da177e4 LT	127	}
	128
	129	static void bind_device(struct raw_config_request *rq)
	130	{
ca8eca68	131	class_device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
53f46542	132	class_device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor),
1da177e4 LT	133	NULL, "raw%d", rq->raw_minor);
	134	}
	135
	136	/*
	137	* Deal with ioctls against the raw-device control interface, to bind
	138	* and unbind other raw devices.
	139	*/
	140	static int raw_ctl_ioctl(struct inode inode, struct file filp,
	141	unsigned int command, unsigned long arg)
	142	{
	143	struct raw_config_request rq;
	144	struct raw_device_data *rawdev;
	145	int err = 0;
	146
	147	switch (command) {
	148	case RAW_SETBIND:
	149	case RAW_GETBIND:
	150
	151	/* First, find out which raw minor we want */
	152
	153	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
	154	err = -EFAULT;
	155	goto out;
	156	}
	157
	158	if (rq.raw_minor < 0 \|\| rq.raw_minor >= MAX_RAW_MINORS) {
	159	err = -EINVAL;
	160	goto out;
	161	}
	162	rawdev = &raw_devices[rq.raw_minor];
	163
	164	if (command == RAW_SETBIND) {
	165	dev_t dev;
	166
	167	/*
	168	* This is like making block devices, so demand the
	169	* same capability
	170	*/
	171	if (!capable(CAP_SYS_ADMIN)) {
	172	err = -EPERM;
	173	goto out;
	174	}
	175
	176	/*
	177	* For now, we don't need to check that the underlying
	178	* block device is present or not: we can do that when
	179	* the raw device is opened. Just check that the
	180	* major/minor numbers make sense.
	181	*/
	182
	183	dev = MKDEV(rq.block_major, rq.block_minor);
	184	if ((rq.block_major == 0 && rq.block_minor != 0) \|\|
	185	MAJOR(dev) != rq.block_major \|\|
	186	MINOR(dev) != rq.block_minor) {
	187	err = -EINVAL;
	188	goto out;
	189	}
	190
8ed965d6	191	mutex_lock(&raw_mutex);
1da177e4	192	if (rawdev->inuse) {
8ed965d6	193	mutex_unlock(&raw_mutex);
1da177e4 LT	194	err = -EBUSY;
	195	goto out;
	196	}
	197	if (rawdev->binding) {
	198	bdput(rawdev->binding);
	199	module_put(THIS_MODULE);
	200	}
	201	if (rq.block_major == 0 && rq.block_minor == 0) {
	202	/* unbind */
	203	rawdev->binding = NULL;
ca8eca68	204	class_device_destroy(raw_class,
ca8eca68	205	MKDEV(RAW_MAJOR, rq.raw_minor));
1da177e4 LT	206	} else {
	207	rawdev->binding = bdget(dev);
	208	if (rawdev->binding == NULL)
	209	err = -ENOMEM;
	210	else {
	211	__module_get(THIS_MODULE);
	212	bind_device(&rq);
	213	}
	214	}
8ed965d6	215	mutex_unlock(&raw_mutex);
1da177e4 LT	216	} else {
	217	struct block_device *bdev;
	218
8ed965d6	219	mutex_lock(&raw_mutex);
1da177e4 LT	220	bdev = rawdev->binding;
	221	if (bdev) {
	222	rq.block_major = MAJOR(bdev->bd_dev);
	223	rq.block_minor = MINOR(bdev->bd_dev);
	224	} else {
	225	rq.block_major = rq.block_minor = 0;
	226	}
8ed965d6	227	mutex_unlock(&raw_mutex);
1da177e4 LT	228	if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
	229	err = -EFAULT;
	230	goto out;
	231	}
	232	}
	233	break;
	234	default:
	235	err = -EINVAL;
	236	break;
	237	}
	238	out:
	239	return err;
	240	}
	241
	242	static ssize_t raw_file_write(struct file file, const char __user buf,
	243	size_t count, loff_t *ppos)
	244	{
	245	struct iovec local_iov = {
	246	.iov_base = (char __user *)buf,
	247	.iov_len = count
	248	};
	249
	250	return generic_file_write_nolock(file, &local_iov, 1, ppos);
	251	}
	252
	253	static ssize_t raw_file_aio_write(struct kiocb iocb, const char __user buf,
	254	size_t count, loff_t pos)
	255	{
	256	struct iovec local_iov = {
	257	.iov_base = (char __user *)buf,
	258	.iov_len = count
	259	};
	260
	261	return generic_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
	262	}
	263
	264
	265	static struct file_operations raw_fops = {
	266	.read = generic_file_read,
	267	.aio_read = generic_file_aio_read,
	268	.write = raw_file_write,
	269	.aio_write = raw_file_aio_write,
	270	.open = raw_open,
	271	.release= raw_release,
	272	.ioctl = raw_ioctl,
	273	.readv = generic_file_readv,
	274	.writev = generic_file_writev,
	275	.owner = THIS_MODULE,
	276	};
	277
	278	static struct file_operations raw_ctl_fops = {
	279	.ioctl = raw_ctl_ioctl,
	280	.open = raw_open,
	281	.owner = THIS_MODULE,
	282	};
	283
	284	static struct cdev raw_cdev = {
	285	.kobj = {.name = "raw", },
	286	.owner = THIS_MODULE,
	287	};
	288
	289	static int __init raw_init(void)
	290	{
	291	int i;
292	dev_t dev = MKDEV(RAW_MAJOR, 0);
293
294	if (register_chrdev_region(dev, MAX_RAW_MINORS, "raw"))
295	goto error;
296
297	cdev_init(&raw_cdev, &raw_fops);
298	if (cdev_add(&raw_cdev, dev, MAX_RAW_MINORS)) {
299	kobject_put(&raw_cdev.kobj);
300	unregister_chrdev_region(dev, MAX_RAW_MINORS);
301	goto error;
302	}
303
ca8eca68	304	raw_class = class_create(THIS_MODULE, "raw");
1da177e4 LT	305	if (IS_ERR(raw_class)) {
	306	printk(KERN_ERR "Error creating raw class.\n");
	307	cdev_del(&raw_cdev);
	308	unregister_chrdev_region(dev, MAX_RAW_MINORS);
	309	goto error;
	310	}
53f46542	311	class_device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
1da177e4 LT	312
	313	devfs_mk_cdev(MKDEV(RAW_MAJOR, 0),
	314	S_IFCHR \| S_IRUGO \| S_IWUGO,
	315	"raw/rawctl");
	316	for (i = 1; i < MAX_RAW_MINORS; i++)
	317	devfs_mk_cdev(MKDEV(RAW_MAJOR, i),
	318	S_IFCHR \| S_IRUGO \| S_IWUGO,
	319	"raw/raw%d", i);
	320	return 0;
	321
	322	error:
	323	printk(KERN_ERR "error register raw device\n");
	324	return 1;
	325	}
	326
	327	static void __exit raw_exit(void)
	328	{
	329	int i;
	330
	331	for (i = 1; i < MAX_RAW_MINORS; i++)
	332	devfs_remove("raw/raw%d", i);
	333	devfs_remove("raw/rawctl");
	334	devfs_remove("raw");
ca8eca68	335	class_device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68	336	class_destroy(raw_class);
1da177e4 LT	337	cdev_del(&raw_cdev);
	338	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
	339	}
	340
	341	module_init(raw_init);
	342	module_exit(raw_exit);
	343	MODULE_LICENSE("GPL");