kernel-ark/drivers/char/raw.c
Martin K. Petersen e1defc4ff0 block: Do away with the notion of hardsect_size
Until now we have had a 1:1 mapping between storage device physical
block size and the logical block sized used when addressing the device.
With SATA 4KB drives coming out that will no longer be the case.  The
sector size will be 4KB but the logical block size will remain
512-bytes.  Hence we need to distinguish between the physical block size
and the logical ditto.

This patch renames hardsect_size to logical_block_size.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-22 23:22:54 +02:00

308 lines
7.0 KiB
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 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");