| /* |
| * 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, 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); |
| unlock_kernel(); |
| 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) |
| { |
| 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 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), 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"); |