[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/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 <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 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, 0, command, arg);
}

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 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;
				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 const struct file_operations raw_fops = {
	.read	=	do_sync_read,
	.aio_read = 	generic_file_aio_read,
	.write	=	do_sync_write,
	.aio_write = 	generic_file_aio_write_nolock,
	.open	=	raw_open,
	.release=	raw_release,
	.ioctl	=	raw_ioctl,
	.owner	=	THIS_MODULE,
};

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

static struct cdev raw_cdev;

static char *raw_nodename(struct device *dev)
{
	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->nodename = raw_nodename;
	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>
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);
62322d25	34	static const struct file_operations raw_ctl_fops; /* forward declaration */
1da177e4 LT	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
c0bed680	57	lock_kernel();
8ed965d6	58	mutex_lock(&raw_mutex);
1da177e4 LT	59
	60	/*
	61	* All we need to do on open is check that the device is bound.
	62	*/
	63	bdev = raw_devices[minor].binding;
	64	err = -ENODEV;
	65	if (!bdev)
	66	goto out;
	67	igrab(bdev->bd_inode);
572c4892	68	err = blkdev_get(bdev, filp->f_mode);
1da177e4 LT	69	if (err)
	70	goto out;
	71	err = bd_claim(bdev, raw_open);
	72	if (err)
	73	goto out1;
e1defc4f	74	err = set_blocksize(bdev, bdev_logical_block_size(bdev));
1da177e4 LT	75	if (err)
	76	goto out2;
	77	filp->f_flags \|= O_DIRECT;
	78	filp->f_mapping = bdev->bd_inode->i_mapping;
	79	if (++raw_devices[minor].inuse == 1)
a7113a96	80	filp->f_path.dentry->d_inode->i_mapping =
1da177e4 LT	81	bdev->bd_inode->i_mapping;
1da177e4 LT	82	filp->private_data = bdev;
8ed965d6	83	mutex_unlock(&raw_mutex);
c0bed680	84	unlock_kernel();
1da177e4 LT	85	return 0;
	86
	87	out2:
	88	bd_release(bdev);
	89	out1:
9a1c3542	90	blkdev_put(bdev, filp->f_mode);
1da177e4	91	out:
8ed965d6	92	mutex_unlock(&raw_mutex);
996ff68d	93	unlock_kernel();
1da177e4 LT	94	return err;
	95	}
	96
	97	/*
	98	* When the final fd which refers to this character-special node is closed, we
	99	* make its ->mapping point back at its own i_data.
	100	*/
	101	static int raw_release(struct inode inode, struct file filp)
	102	{
	103	const int minor= iminor(inode);
	104	struct block_device *bdev;
	105
8ed965d6	106	mutex_lock(&raw_mutex);
1da177e4 LT	107	bdev = raw_devices[minor].binding;
	108	if (--raw_devices[minor].inuse == 0) {
	109	/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
	110	inode->i_mapping = &inode->i_data;
	111	inode->i_mapping->backing_dev_info = &default_backing_dev_info;
	112	}
8ed965d6	113	mutex_unlock(&raw_mutex);
1da177e4 LT	114
1da177e4 LT	115	bd_release(bdev);
9a1c3542	116	blkdev_put(bdev, filp->f_mode);
1da177e4 LT	117	return 0;
	118	}
	119
	120	/*
	121	* Forward ioctls to the underlying block device.
	122	*/
	123	static int
	124	raw_ioctl(struct inode inode, struct file filp,
	125	unsigned int command, unsigned long arg)
	126	{
	127	struct block_device *bdev = filp->private_data;
	128
56b26add	129	return blkdev_ioctl(bdev, 0, command, arg);
1da177e4 LT	130	}
	131
	132	static void bind_device(struct raw_config_request *rq)
	133	{
38ca6c34	134	device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
03457cd4 GKH	135	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL,
03457cd4 GKH	136	"raw%d", rq->raw_minor);
1da177e4 LT	137	}
	138
	139	/*
	140	* Deal with ioctls against the raw-device control interface, to bind
	141	* and unbind other raw devices.
	142	*/
	143	static int raw_ctl_ioctl(struct inode inode, struct file filp,
	144	unsigned int command, unsigned long arg)
	145	{
	146	struct raw_config_request rq;
	147	struct raw_device_data *rawdev;
	148	int err = 0;
	149
	150	switch (command) {
	151	case RAW_SETBIND:
	152	case RAW_GETBIND:
	153
	154	/* First, find out which raw minor we want */
	155
	156	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
	157	err = -EFAULT;
	158	goto out;
	159	}
	160
38584c14	161	if (rq.raw_minor <= 0 \|\| rq.raw_minor >= MAX_RAW_MINORS) {
1da177e4 LT	162	err = -EINVAL;
	163	goto out;
	164	}
	165	rawdev = &raw_devices[rq.raw_minor];
	166
	167	if (command == RAW_SETBIND) {
	168	dev_t dev;
	169
	170	/*
	171	* This is like making block devices, so demand the
	172	* same capability
	173	*/
	174	if (!capable(CAP_SYS_ADMIN)) {
	175	err = -EPERM;
	176	goto out;
	177	}
	178
	179	/*
	180	* For now, we don't need to check that the underlying
	181	* block device is present or not: we can do that when
	182	* the raw device is opened. Just check that the
	183	* major/minor numbers make sense.
	184	*/
	185
	186	dev = MKDEV(rq.block_major, rq.block_minor);
	187	if ((rq.block_major == 0 && rq.block_minor != 0) \|\|
	188	MAJOR(dev) != rq.block_major \|\|
	189	MINOR(dev) != rq.block_minor) {
	190	err = -EINVAL;
	191	goto out;
	192	}
	193
8ed965d6	194	mutex_lock(&raw_mutex);
1da177e4	195	if (rawdev->inuse) {
8ed965d6	196	mutex_unlock(&raw_mutex);
1da177e4 LT	197	err = -EBUSY;
	198	goto out;
	199	}
	200	if (rawdev->binding) {
	201	bdput(rawdev->binding);
	202	module_put(THIS_MODULE);
	203	}
	204	if (rq.block_major == 0 && rq.block_minor == 0) {
	205	/* unbind */
	206	rawdev->binding = NULL;
38ca6c34	207	device_destroy(raw_class,
ca8eca68	208	MKDEV(RAW_MAJOR, rq.raw_minor));
1da177e4 LT	209	} else {
	210	rawdev->binding = bdget(dev);
	211	if (rawdev->binding == NULL)
	212	err = -ENOMEM;
	213	else {
	214	__module_get(THIS_MODULE);
	215	bind_device(&rq);
	216	}
	217	}
8ed965d6	218	mutex_unlock(&raw_mutex);
1da177e4 LT	219	} else {
	220	struct block_device *bdev;
	221
8ed965d6	222	mutex_lock(&raw_mutex);
1da177e4 LT	223	bdev = rawdev->binding;
	224	if (bdev) {
	225	rq.block_major = MAJOR(bdev->bd_dev);
	226	rq.block_minor = MINOR(bdev->bd_dev);
	227	} else {
	228	rq.block_major = rq.block_minor = 0;
	229	}
8ed965d6	230	mutex_unlock(&raw_mutex);
1da177e4 LT	231	if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
	232	err = -EFAULT;
	233	goto out;
	234	}
	235	}
	236	break;
	237	default:
	238	err = -EINVAL;
	239	break;
	240	}
	241	out:
	242	return err;
	243	}
	244
62322d25	245	static const struct file_operations raw_fops = {
543ade1f	246	.read = do_sync_read,
1da177e4	247	.aio_read = generic_file_aio_read,
543ade1f	248	.write = do_sync_write,
027445c3	249	.aio_write = generic_file_aio_write_nolock,
1da177e4 LT	250	.open = raw_open,
	251	.release= raw_release,
	252	.ioctl = raw_ioctl,
1da177e4 LT	253	.owner = THIS_MODULE,
	254	};
	255
62322d25	256	static const struct file_operations raw_ctl_fops = {
1da177e4 LT	257	.ioctl = raw_ctl_ioctl,
	258	.open = raw_open,
	259	.owner = THIS_MODULE,
	260	};
	261
7e7654a9	262	static struct cdev raw_cdev;
1da177e4	263
6fd46933 KS	264	static char raw_nodename(struct device dev)
	265	{
	266	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
	267	}
	268
1da177e4 LT	269	static int __init raw_init(void)
1da177e4 LT	270	{
1da177e4	271	dev_t dev = MKDEV(RAW_MAJOR, 0);
3e26a423	272	int ret;
1da177e4	273
3e26a423 REB	274	ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
3e26a423 REB	275	if (ret)
1da177e4 LT	276	goto error;
	277
	278	cdev_init(&raw_cdev, &raw_fops);
3e26a423 REB	279	ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
3e26a423 REB	280	if (ret) {
1da177e4	281	kobject_put(&raw_cdev.kobj);
3e26a423	282	goto error_region;
1da177e4 LT	283	}
1da177e4 LT	284
ca8eca68	285	raw_class = class_create(THIS_MODULE, "raw");
1da177e4 LT	286	if (IS_ERR(raw_class)) {
	287	printk(KERN_ERR "Error creating raw class.\n");
	288	cdev_del(&raw_cdev);
3e26a423 REB	289	ret = PTR_ERR(raw_class);
3e26a423 REB	290	goto error_region;
1da177e4	291	}
6fd46933	292	raw_class->nodename = raw_nodename;
03457cd4	293	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
1da177e4	294
1da177e4 LT	295	return 0;
1da177e4 LT	296
3e26a423 REB	297	error_region:
3e26a423 REB	298	unregister_chrdev_region(dev, MAX_RAW_MINORS);
1da177e4	299	error:
3e26a423	300	return ret;
1da177e4 LT	301	}
	302
	303	static void __exit raw_exit(void)
	304	{
38ca6c34	305	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68	306	class_destroy(raw_class);
1da177e4 LT	307	cdev_del(&raw_cdev);
	308	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
	309	}
	310
	311	module_init(raw_init);
	312	module_exit(raw_exit);
	313	MODULE_LICENSE("GPL");