Merge tag 'locks-v3.20-2' of git://git.samba.org/jlayton/linux
[deliverable/linux.git] / drivers / char / raw.c
CommitLineData
1da177e4
LT
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>
1da177e4
LT
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>
8ed965d6 21#include <linux/mutex.h>
5a0e3ad6 22#include <linux/gfp.h>
c4a04727 23#include <linux/compat.h>
0078bff5 24#include <linux/vmalloc.h>
1da177e4
LT
25
26#include <asm/uaccess.h>
27
28struct raw_device_data {
29 struct block_device *binding;
30 int inuse;
31};
32
ca8eca68 33static struct class *raw_class;
0078bff5 34static struct raw_device_data *raw_devices;
8ed965d6 35static DEFINE_MUTEX(raw_mutex);
62322d25 36static const struct file_operations raw_ctl_fops; /* forward declaration */
1da177e4 37
0078bff5
JK
38static int max_raw_minors = MAX_RAW_MINORS;
39
40module_param(max_raw_minors, int, 0);
41MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
42
1da177e4
LT
43/*
44 * Open/close code for raw IO.
45 *
46 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
47 * point at the blockdev's address_space and set the file handle to use
48 * O_DIRECT.
49 *
50 * Set the device's soft blocksize to the minimum possible. This gives the
51 * finest possible alignment and has no adverse impact on performance.
52 */
53static int raw_open(struct inode *inode, struct file *filp)
54{
55 const int minor = iminor(inode);
56 struct block_device *bdev;
57 int err;
58
59 if (minor == 0) { /* It is the control device */
60 filp->f_op = &raw_ctl_fops;
61 return 0;
62 }
63
8ed965d6 64 mutex_lock(&raw_mutex);
1da177e4
LT
65
66 /*
67 * All we need to do on open is check that the device is bound.
68 */
69 bdev = raw_devices[minor].binding;
70 err = -ENODEV;
71 if (!bdev)
72 goto out;
73 igrab(bdev->bd_inode);
e525fd89 74 err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
1da177e4
LT
75 if (err)
76 goto out;
e1defc4f 77 err = set_blocksize(bdev, bdev_logical_block_size(bdev));
1da177e4 78 if (err)
e525fd89 79 goto out1;
1da177e4
LT
80 filp->f_flags |= O_DIRECT;
81 filp->f_mapping = bdev->bd_inode->i_mapping;
82 if (++raw_devices[minor].inuse == 1)
496ad9aa 83 file_inode(filp)->i_mapping =
1da177e4
LT
84 bdev->bd_inode->i_mapping;
85 filp->private_data = bdev;
8ed965d6 86 mutex_unlock(&raw_mutex);
1da177e4
LT
87 return 0;
88
1da177e4 89out1:
e525fd89 90 blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
1da177e4 91out:
8ed965d6 92 mutex_unlock(&raw_mutex);
1da177e4
LT
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 */
100static int raw_release(struct inode *inode, struct file *filp)
101{
102 const int minor= iminor(inode);
103 struct block_device *bdev;
104
8ed965d6 105 mutex_lock(&raw_mutex);
1da177e4 106 bdev = raw_devices[minor].binding;
b83ae6d4 107 if (--raw_devices[minor].inuse == 0)
1da177e4
LT
108 /* Here inode->i_mapping == bdev->bd_inode->i_mapping */
109 inode->i_mapping = &inode->i_data;
8ed965d6 110 mutex_unlock(&raw_mutex);
1da177e4 111
e525fd89 112 blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
1da177e4
LT
113 return 0;
114}
115
116/*
117 * Forward ioctls to the underlying block device.
118 */
55929332
AB
119static long
120raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
1da177e4
LT
121{
122 struct block_device *bdev = filp->private_data;
c4a04727
AV
123 return blkdev_ioctl(bdev, 0, command, arg);
124}
125
126static int bind_set(int number, u64 major, u64 minor)
127{
128 dev_t dev = MKDEV(major, minor);
129 struct raw_device_data *rawdev;
130 int err = 0;
131
0078bff5 132 if (number <= 0 || number >= max_raw_minors)
c4a04727
AV
133 return -EINVAL;
134
135 if (MAJOR(dev) != major || MINOR(dev) != minor)
136 return -EINVAL;
137
138 rawdev = &raw_devices[number];
1da177e4 139
c4a04727
AV
140 /*
141 * This is like making block devices, so demand the
142 * same capability
143 */
144 if (!capable(CAP_SYS_ADMIN))
145 return -EPERM;
146
147 /*
148 * For now, we don't need to check that the underlying
149 * block device is present or not: we can do that when
150 * the raw device is opened. Just check that the
151 * major/minor numbers make sense.
152 */
153
154 if (MAJOR(dev) == 0 && dev != 0)
155 return -EINVAL;
55929332 156
c4a04727
AV
157 mutex_lock(&raw_mutex);
158 if (rawdev->inuse) {
159 mutex_unlock(&raw_mutex);
160 return -EBUSY;
161 }
162 if (rawdev->binding) {
163 bdput(rawdev->binding);
164 module_put(THIS_MODULE);
165 }
166 if (!dev) {
167 /* unbind */
168 rawdev->binding = NULL;
169 device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
170 } else {
171 rawdev->binding = bdget(dev);
172 if (rawdev->binding == NULL) {
173 err = -ENOMEM;
174 } else {
175 dev_t raw = MKDEV(RAW_MAJOR, number);
176 __module_get(THIS_MODULE);
177 device_destroy(raw_class, raw);
178 device_create(raw_class, NULL, raw, NULL,
179 "raw%d", number);
180 }
181 }
182 mutex_unlock(&raw_mutex);
183 return err;
1da177e4
LT
184}
185
c4a04727 186static int bind_get(int number, dev_t *dev)
1da177e4 187{
c4a04727
AV
188 struct raw_device_data *rawdev;
189 struct block_device *bdev;
190
5bbb2ae3 191 if (number <= 0 || number >= max_raw_minors)
c4a04727
AV
192 return -EINVAL;
193
194 rawdev = &raw_devices[number];
195
196 mutex_lock(&raw_mutex);
197 bdev = rawdev->binding;
198 *dev = bdev ? bdev->bd_dev : 0;
199 mutex_unlock(&raw_mutex);
200 return 0;
1da177e4
LT
201}
202
203/*
204 * Deal with ioctls against the raw-device control interface, to bind
205 * and unbind other raw devices.
206 */
55929332
AB
207static long raw_ctl_ioctl(struct file *filp, unsigned int command,
208 unsigned long arg)
1da177e4
LT
209{
210 struct raw_config_request rq;
c4a04727
AV
211 dev_t dev;
212 int err;
1da177e4
LT
213
214 switch (command) {
215 case RAW_SETBIND:
c4a04727
AV
216 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
217 return -EFAULT;
218
219 return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
220
1da177e4 221 case RAW_GETBIND:
c4a04727
AV
222 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
223 return -EFAULT;
1da177e4 224
c4a04727
AV
225 err = bind_get(rq.raw_minor, &dev);
226 if (err)
227 return err;
1da177e4 228
c4a04727
AV
229 rq.block_major = MAJOR(dev);
230 rq.block_minor = MINOR(dev);
1da177e4 231
c4a04727
AV
232 if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
233 return -EFAULT;
234
235 return 0;
1da177e4 236 }
c4a04727
AV
237
238 return -EINVAL;
239}
240
241#ifdef CONFIG_COMPAT
242struct raw32_config_request {
243 compat_int_t raw_minor;
244 compat_u64 block_major;
245 compat_u64 block_minor;
246};
247
248static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
249 unsigned long arg)
250{
251 struct raw32_config_request __user *user_req = compat_ptr(arg);
252 struct raw32_config_request rq;
253 dev_t dev;
254 int err = 0;
255
256 switch (cmd) {
257 case RAW_SETBIND:
258 if (copy_from_user(&rq, user_req, sizeof(rq)))
259 return -EFAULT;
260
261 return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
262
263 case RAW_GETBIND:
264 if (copy_from_user(&rq, user_req, sizeof(rq)))
265 return -EFAULT;
266
267 err = bind_get(rq.raw_minor, &dev);
268 if (err)
269 return err;
270
271 rq.block_major = MAJOR(dev);
272 rq.block_minor = MINOR(dev);
273
274 if (copy_to_user(user_req, &rq, sizeof(rq)))
275 return -EFAULT;
276
277 return 0;
278 }
279
280 return -EINVAL;
1da177e4 281}
c4a04727 282#endif
1da177e4 283
62322d25 284static const struct file_operations raw_fops = {
aad4f8bb 285 .read = new_sync_read,
b2de525f 286 .read_iter = blkdev_read_iter,
1456c0a8
AV
287 .write = new_sync_write,
288 .write_iter = blkdev_write_iter,
55929332
AB
289 .fsync = blkdev_fsync,
290 .open = raw_open,
291 .release = raw_release,
292 .unlocked_ioctl = raw_ioctl,
cb3b9cf8 293 .llseek = default_llseek,
55929332 294 .owner = THIS_MODULE,
1da177e4
LT
295};
296
62322d25 297static const struct file_operations raw_ctl_fops = {
55929332 298 .unlocked_ioctl = raw_ctl_ioctl,
c4a04727
AV
299#ifdef CONFIG_COMPAT
300 .compat_ioctl = raw_ctl_compat_ioctl,
301#endif
55929332
AB
302 .open = raw_open,
303 .owner = THIS_MODULE,
cb3b9cf8 304 .llseek = noop_llseek,
1da177e4
LT
305};
306
7e7654a9 307static struct cdev raw_cdev;
1da177e4 308
2c9ede55 309static char *raw_devnode(struct device *dev, umode_t *mode)
6fd46933
KS
310{
311 return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
312}
313
1da177e4
LT
314static int __init raw_init(void)
315{
1da177e4 316 dev_t dev = MKDEV(RAW_MAJOR, 0);
3e26a423 317 int ret;
1da177e4 318
0078bff5
JK
319 if (max_raw_minors < 1 || max_raw_minors > 65536) {
320 printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
321 " between 1 and 65536), using %d\n", MAX_RAW_MINORS);
322 max_raw_minors = MAX_RAW_MINORS;
323 }
324
8e03bd65 325 raw_devices = vzalloc(sizeof(struct raw_device_data) * max_raw_minors);
0078bff5
JK
326 if (!raw_devices) {
327 printk(KERN_ERR "Not enough memory for raw device structures\n");
328 ret = -ENOMEM;
329 goto error;
330 }
0078bff5
JK
331
332 ret = register_chrdev_region(dev, max_raw_minors, "raw");
3e26a423 333 if (ret)
1da177e4
LT
334 goto error;
335
336 cdev_init(&raw_cdev, &raw_fops);
0078bff5 337 ret = cdev_add(&raw_cdev, dev, max_raw_minors);
3e26a423 338 if (ret) {
3e26a423 339 goto error_region;
1da177e4
LT
340 }
341
ca8eca68 342 raw_class = class_create(THIS_MODULE, "raw");
1da177e4
LT
343 if (IS_ERR(raw_class)) {
344 printk(KERN_ERR "Error creating raw class.\n");
345 cdev_del(&raw_cdev);
3e26a423
REB
346 ret = PTR_ERR(raw_class);
347 goto error_region;
1da177e4 348 }
e454cea2 349 raw_class->devnode = raw_devnode;
03457cd4 350 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
1da177e4 351
1da177e4
LT
352 return 0;
353
3e26a423 354error_region:
0078bff5 355 unregister_chrdev_region(dev, max_raw_minors);
1da177e4 356error:
0078bff5 357 vfree(raw_devices);
3e26a423 358 return ret;
1da177e4
LT
359}
360
361static void __exit raw_exit(void)
362{
38ca6c34 363 device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68 364 class_destroy(raw_class);
1da177e4 365 cdev_del(&raw_cdev);
0078bff5 366 unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);
1da177e4
LT
367}
368
369module_init(raw_init);
370module_exit(raw_exit);
371MODULE_LICENSE("GPL");
This page took 1.060532 seconds and 5 git commands to generate.