/* * 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 <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;	} 	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_path.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 intraw_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){	device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor),		      "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 = {	.kobj	=	{.name = "raw", },	.owner	=	THIS_MODULE,}; 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;	}	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), "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");