summaryrefslogtreecommitdiff
path: root/drivers/char/raw.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/char/raw.c')
-rw-r--r--drivers/char/raw.c342
1 files changed, 342 insertions, 0 deletions
diff --git a/drivers/char/raw.c b/drivers/char/raw.c
new file mode 100644
index 000000000000..a2e33ec79615
--- /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");
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-05 05:05:12 +0000