device create: char: convert device_create_drvdata to device_create
[linux-2.6.git] / drivers / char / raw.c
1 /*
2  * linux/drivers/char/raw.c
3  *
4  * Front-end raw character devices.  These can be bound to any block
5  * devices to provide genuine Unix raw character device semantics.
6  *
7  * We reserve minor number 0 for a control interface.  ioctl()s on this
8  * device are used to bind the other minor numbers to block devices.
9  */
10
11 #include <linux/init.h>
12 #include <linux/fs.h>
13 #include <linux/major.h>
14 #include <linux/blkdev.h>
15 #include <linux/module.h>
16 #include <linux/raw.h>
17 #include <linux/capability.h>
18 #include <linux/uio.h>
19 #include <linux/cdev.h>
20 #include <linux/device.h>
21 #include <linux/mutex.h>
22 #include <linux/smp_lock.h>
23
24 #include <asm/uaccess.h>
25
26 struct raw_device_data {
27         struct block_device *binding;
28         int inuse;
29 };
30
31 static struct class *raw_class;
32 static struct raw_device_data raw_devices[MAX_RAW_MINORS];
33 static DEFINE_MUTEX(raw_mutex);
34 static const struct file_operations raw_ctl_fops; /* forward declaration */
35
36 /*
37  * Open/close code for raw IO.
38  *
39  * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
40  * point at the blockdev's address_space and set the file handle to use
41  * O_DIRECT.
42  *
43  * Set the device's soft blocksize to the minimum possible.  This gives the
44  * finest possible alignment and has no adverse impact on performance.
45  */
46 static int raw_open(struct inode *inode, struct file *filp)
47 {
48         const int minor = iminor(inode);
49         struct block_device *bdev;
50         int err;
51
52         if (minor == 0) {       /* It is the control device */
53                 filp->f_op = &raw_ctl_fops;
54                 return 0;
55         }
56
57         lock_kernel();
58         mutex_lock(&raw_mutex);
59
60         /*
61          * All we need to do on open is check that the device is bound.
62          */
63         bdev = raw_devices[minor].binding;
64         err = -ENODEV;
65         if (!bdev)
66                 goto out;
67         igrab(bdev->bd_inode);
68         err = blkdev_get(bdev, filp->f_mode, 0);
69         if (err)
70                 goto out;
71         err = bd_claim(bdev, raw_open);
72         if (err)
73                 goto out1;
74         err = set_blocksize(bdev, bdev_hardsect_size(bdev));
75         if (err)
76                 goto out2;
77         filp->f_flags |= O_DIRECT;
78         filp->f_mapping = bdev->bd_inode->i_mapping;
79         if (++raw_devices[minor].inuse == 1)
80                 filp->f_path.dentry->d_inode->i_mapping =
81                         bdev->bd_inode->i_mapping;
82         filp->private_data = bdev;
83         mutex_unlock(&raw_mutex);
84         unlock_kernel();
85         return 0;
86
87 out2:
88         bd_release(bdev);
89 out1:
90         blkdev_put(bdev);
91 out:
92         mutex_unlock(&raw_mutex);
93         return err;
94 }
95
96 /*
97  * When the final fd which refers to this character-special node is closed, we
98  * make its ->mapping point back at its own i_data.
99  */
100 static int raw_release(struct inode *inode, struct file *filp)
101 {
102         const int minor= iminor(inode);
103         struct block_device *bdev;
104
105         mutex_lock(&raw_mutex);
106         bdev = raw_devices[minor].binding;
107         if (--raw_devices[minor].inuse == 0) {
108                 /* Here  inode->i_mapping == bdev->bd_inode->i_mapping  */
109                 inode->i_mapping = &inode->i_data;
110                 inode->i_mapping->backing_dev_info = &default_backing_dev_info;
111         }
112         mutex_unlock(&raw_mutex);
113
114         bd_release(bdev);
115         blkdev_put(bdev);
116         return 0;
117 }
118
119 /*
120  * Forward ioctls to the underlying block device.
121  */
122 static int
123 raw_ioctl(struct inode *inode, struct file *filp,
124                   unsigned int command, unsigned long arg)
125 {
126         struct block_device *bdev = filp->private_data;
127
128         return blkdev_ioctl(bdev->bd_inode, NULL, command, arg);
129 }
130
131 static void bind_device(struct raw_config_request *rq)
132 {
133         device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
134         device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL,
135                       "raw%d", rq->raw_minor);
136 }
137
138 /*
139  * Deal with ioctls against the raw-device control interface, to bind
140  * and unbind other raw devices.
141  */
142 static int raw_ctl_ioctl(struct inode *inode, struct file *filp,
143                         unsigned int command, unsigned long arg)
144 {
145         struct raw_config_request rq;
146         struct raw_device_data *rawdev;
147         int err = 0;
148
149         switch (command) {
150         case RAW_SETBIND:
151         case RAW_GETBIND:
152
153                 /* First, find out which raw minor we want */
154
155                 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
156                         err = -EFAULT;
157                         goto out;
158                 }
159
160                 if (rq.raw_minor <= 0 || rq.raw_minor >= MAX_RAW_MINORS) {
161                         err = -EINVAL;
162                         goto out;
163                 }
164                 rawdev = &raw_devices[rq.raw_minor];
165
166                 if (command == RAW_SETBIND) {
167                         dev_t dev;
168
169                         /*
170                          * This is like making block devices, so demand the
171                          * same capability
172                          */
173                         if (!capable(CAP_SYS_ADMIN)) {
174                                 err = -EPERM;
175                                 goto out;
176                         }
177
178                         /*
179                          * For now, we don't need to check that the underlying
180                          * block device is present or not: we can do that when
181                          * the raw device is opened.  Just check that the
182                          * major/minor numbers make sense.
183                          */
184
185                         dev = MKDEV(rq.block_major, rq.block_minor);
186                         if ((rq.block_major == 0 && rq.block_minor != 0) ||
187                                         MAJOR(dev) != rq.block_major ||
188                                         MINOR(dev) != rq.block_minor) {
189                                 err = -EINVAL;
190                                 goto out;
191                         }
192
193                         mutex_lock(&raw_mutex);
194                         if (rawdev->inuse) {
195                                 mutex_unlock(&raw_mutex);
196                                 err = -EBUSY;
197                                 goto out;
198                         }
199                         if (rawdev->binding) {
200                                 bdput(rawdev->binding);
201                                 module_put(THIS_MODULE);
202                         }
203                         if (rq.block_major == 0 && rq.block_minor == 0) {
204                                 /* unbind */
205                                 rawdev->binding = NULL;
206                                 device_destroy(raw_class,
207                                                 MKDEV(RAW_MAJOR, rq.raw_minor));
208                         } else {
209                                 rawdev->binding = bdget(dev);
210                                 if (rawdev->binding == NULL)
211                                         err = -ENOMEM;
212                                 else {
213                                         __module_get(THIS_MODULE);
214                                         bind_device(&rq);
215                                 }
216                         }
217                         mutex_unlock(&raw_mutex);
218                 } else {
219                         struct block_device *bdev;
220
221                         mutex_lock(&raw_mutex);
222                         bdev = rawdev->binding;
223                         if (bdev) {
224                                 rq.block_major = MAJOR(bdev->bd_dev);
225                                 rq.block_minor = MINOR(bdev->bd_dev);
226                         } else {
227                                 rq.block_major = rq.block_minor = 0;
228                         }
229                         mutex_unlock(&raw_mutex);
230                         if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
231                                 err = -EFAULT;
232                                 goto out;
233                         }
234                 }
235                 break;
236         default:
237                 err = -EINVAL;
238                 break;
239         }
240 out:
241         return err;
242 }
243
244 static const struct file_operations raw_fops = {
245         .read   =       do_sync_read,
246         .aio_read =     generic_file_aio_read,
247         .write  =       do_sync_write,
248         .aio_write =    generic_file_aio_write_nolock,
249         .open   =       raw_open,
250         .release=       raw_release,
251         .ioctl  =       raw_ioctl,
252         .owner  =       THIS_MODULE,
253 };
254
255 static const struct file_operations raw_ctl_fops = {
256         .ioctl  =       raw_ctl_ioctl,
257         .open   =       raw_open,
258         .owner  =       THIS_MODULE,
259 };
260
261 static struct cdev raw_cdev;
262
263 static int __init raw_init(void)
264 {
265         dev_t dev = MKDEV(RAW_MAJOR, 0);
266         int ret;
267
268         ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
269         if (ret)
270                 goto error;
271
272         cdev_init(&raw_cdev, &raw_fops);
273         ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
274         if (ret) {
275                 kobject_put(&raw_cdev.kobj);
276                 goto error_region;
277         }
278
279         raw_class = class_create(THIS_MODULE, "raw");
280         if (IS_ERR(raw_class)) {
281                 printk(KERN_ERR "Error creating raw class.\n");
282                 cdev_del(&raw_cdev);
283                 ret = PTR_ERR(raw_class);
284                 goto error_region;
285         }
286         device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
287
288         return 0;
289
290 error_region:
291         unregister_chrdev_region(dev, MAX_RAW_MINORS);
292 error:
293         return ret;
294 }
295
296 static void __exit raw_exit(void)
297 {
298         device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
299         class_destroy(raw_class);
300         cdev_del(&raw_cdev);
301         unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
302 }
303
304 module_init(raw_init);
305 module_exit(raw_exit);
306 MODULE_LICENSE("GPL");