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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/char/raw.c | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'drivers/char/raw.c')
-rw-r--r-- | drivers/char/raw.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/drivers/char/raw.c b/drivers/char/raw.c new file mode 100644 index 0000000..a2e33ec --- /dev/null +++ b/drivers/char/raw.c @@ -0,0 +1,342 @@ +/* + * 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 <asm/uaccess.h> + +struct raw_device_data { + struct block_device *binding; + int inuse; +}; + +static struct class_simple *raw_class; +static struct raw_device_data raw_devices[MAX_RAW_MINORS]; +static DECLARE_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; + } + + down(&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; + up(&raw_mutex); + return 0; + +out2: + bd_release(bdev); +out1: + blkdev_put(bdev); +out: + up(&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; + + down(&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; + } + up(&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 ioctl_by_bdev(bdev, command, arg); +} + +static void bind_device(struct raw_config_request *rq) +{ + class_simple_device_remove(MKDEV(RAW_MAJOR, rq->raw_minor)); + class_simple_device_add(raw_class, 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; + } + + down(&raw_mutex); + if (rawdev->inuse) { + up(&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_simple_device_remove(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); + } + } + up(&raw_mutex); + } else { + struct block_device *bdev; + + down(&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; + } + up(&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_simple_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_simple_device_add(raw_class, 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_simple_device_remove(MKDEV(RAW_MAJOR, 0)); + class_simple_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"); |