ia64/linux-2.6.18-xen.hg

view drivers/char/raw.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
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 */
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>
23 #include <asm/uaccess.h>
25 struct raw_device_data {
26 struct block_device *binding;
27 int inuse;
28 };
30 static struct class *raw_class;
31 static struct raw_device_data raw_devices[MAX_RAW_MINORS];
32 static DEFINE_MUTEX(raw_mutex);
33 static const struct file_operations raw_ctl_fops; /* forward declaration */
35 /*
36 * Open/close code for raw IO.
37 *
38 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
39 * point at the blockdev's address_space and set the file handle to use
40 * O_DIRECT.
41 *
42 * Set the device's soft blocksize to the minimum possible. This gives the
43 * finest possible alignment and has no adverse impact on performance.
44 */
45 static int raw_open(struct inode *inode, struct file *filp)
46 {
47 const int minor = iminor(inode);
48 struct block_device *bdev;
49 int err;
51 if (minor == 0) { /* It is the control device */
52 filp->f_op = &raw_ctl_fops;
53 return 0;
54 }
56 mutex_lock(&raw_mutex);
58 /*
59 * All we need to do on open is check that the device is bound.
60 */
61 bdev = raw_devices[minor].binding;
62 err = -ENODEV;
63 if (!bdev)
64 goto out;
65 igrab(bdev->bd_inode);
66 err = blkdev_get(bdev, filp->f_mode, 0);
67 if (err)
68 goto out;
69 err = bd_claim(bdev, raw_open);
70 if (err)
71 goto out1;
72 err = set_blocksize(bdev, bdev_hardsect_size(bdev));
73 if (err)
74 goto out2;
75 filp->f_flags |= O_DIRECT;
76 filp->f_mapping = bdev->bd_inode->i_mapping;
77 if (++raw_devices[minor].inuse == 1)
78 filp->f_dentry->d_inode->i_mapping =
79 bdev->bd_inode->i_mapping;
80 filp->private_data = bdev;
81 mutex_unlock(&raw_mutex);
82 return 0;
84 out2:
85 bd_release(bdev);
86 out1:
87 blkdev_put(bdev);
88 out:
89 mutex_unlock(&raw_mutex);
90 return err;
91 }
93 /*
94 * When the final fd which refers to this character-special node is closed, we
95 * make its ->mapping point back at its own i_data.
96 */
97 static int raw_release(struct inode *inode, struct file *filp)
98 {
99 const int minor= iminor(inode);
100 struct block_device *bdev;
102 mutex_lock(&raw_mutex);
103 bdev = raw_devices[minor].binding;
104 if (--raw_devices[minor].inuse == 0) {
105 /* Here inode->i_mapping == bdev->bd_inode->i_mapping */
106 inode->i_mapping = &inode->i_data;
107 inode->i_mapping->backing_dev_info = &default_backing_dev_info;
108 }
109 mutex_unlock(&raw_mutex);
111 bd_release(bdev);
112 blkdev_put(bdev);
113 return 0;
114 }
116 /*
117 * Forward ioctls to the underlying block device.
118 */
119 static int
120 raw_ioctl(struct inode *inode, struct file *filp,
121 unsigned int command, unsigned long arg)
122 {
123 struct block_device *bdev = filp->private_data;
125 return blkdev_ioctl(bdev->bd_inode, NULL, command, arg);
126 }
128 static void bind_device(struct raw_config_request *rq)
129 {
130 class_device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
131 class_device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor),
132 NULL, "raw%d", rq->raw_minor);
133 }
135 /*
136 * Deal with ioctls against the raw-device control interface, to bind
137 * and unbind other raw devices.
138 */
139 static int raw_ctl_ioctl(struct inode *inode, struct file *filp,
140 unsigned int command, unsigned long arg)
141 {
142 struct raw_config_request rq;
143 struct raw_device_data *rawdev;
144 int err = 0;
146 switch (command) {
147 case RAW_SETBIND:
148 case RAW_GETBIND:
150 /* First, find out which raw minor we want */
152 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
153 err = -EFAULT;
154 goto out;
155 }
157 if (rq.raw_minor < 0 || rq.raw_minor >= MAX_RAW_MINORS) {
158 err = -EINVAL;
159 goto out;
160 }
161 rawdev = &raw_devices[rq.raw_minor];
163 if (command == RAW_SETBIND) {
164 dev_t dev;
166 /*
167 * This is like making block devices, so demand the
168 * same capability
169 */
170 if (!capable(CAP_SYS_ADMIN)) {
171 err = -EPERM;
172 goto out;
173 }
175 /*
176 * For now, we don't need to check that the underlying
177 * block device is present or not: we can do that when
178 * the raw device is opened. Just check that the
179 * major/minor numbers make sense.
180 */
182 dev = MKDEV(rq.block_major, rq.block_minor);
183 if ((rq.block_major == 0 && rq.block_minor != 0) ||
184 MAJOR(dev) != rq.block_major ||
185 MINOR(dev) != rq.block_minor) {
186 err = -EINVAL;
187 goto out;
188 }
190 mutex_lock(&raw_mutex);
191 if (rawdev->inuse) {
192 mutex_unlock(&raw_mutex);
193 err = -EBUSY;
194 goto out;
195 }
196 if (rawdev->binding) {
197 bdput(rawdev->binding);
198 module_put(THIS_MODULE);
199 }
200 if (rq.block_major == 0 && rq.block_minor == 0) {
201 /* unbind */
202 rawdev->binding = NULL;
203 class_device_destroy(raw_class,
204 MKDEV(RAW_MAJOR, rq.raw_minor));
205 } else {
206 rawdev->binding = bdget(dev);
207 if (rawdev->binding == NULL)
208 err = -ENOMEM;
209 else {
210 __module_get(THIS_MODULE);
211 bind_device(&rq);
212 }
213 }
214 mutex_unlock(&raw_mutex);
215 } else {
216 struct block_device *bdev;
218 mutex_lock(&raw_mutex);
219 bdev = rawdev->binding;
220 if (bdev) {
221 rq.block_major = MAJOR(bdev->bd_dev);
222 rq.block_minor = MINOR(bdev->bd_dev);
223 } else {
224 rq.block_major = rq.block_minor = 0;
225 }
226 mutex_unlock(&raw_mutex);
227 if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
228 err = -EFAULT;
229 goto out;
230 }
231 }
232 break;
233 default:
234 err = -EINVAL;
235 break;
236 }
237 out:
238 return err;
239 }
241 static ssize_t raw_file_write(struct file *file, const char __user *buf,
242 size_t count, loff_t *ppos)
243 {
244 struct iovec local_iov = {
245 .iov_base = (char __user *)buf,
246 .iov_len = count
247 };
249 return generic_file_write_nolock(file, &local_iov, 1, ppos);
250 }
252 static ssize_t raw_file_aio_write(struct kiocb *iocb, const char __user *buf,
253 size_t count, loff_t pos)
254 {
255 struct iovec local_iov = {
256 .iov_base = (char __user *)buf,
257 .iov_len = count
258 };
260 return generic_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
261 }
264 static const struct file_operations raw_fops = {
265 .read = generic_file_read,
266 .aio_read = generic_file_aio_read,
267 .write = raw_file_write,
268 .aio_write = raw_file_aio_write,
269 .open = raw_open,
270 .release= raw_release,
271 .ioctl = raw_ioctl,
272 .readv = generic_file_readv,
273 .writev = generic_file_writev,
274 .owner = THIS_MODULE,
275 };
277 static const struct file_operations raw_ctl_fops = {
278 .ioctl = raw_ctl_ioctl,
279 .open = raw_open,
280 .owner = THIS_MODULE,
281 };
283 static struct cdev raw_cdev = {
284 .kobj = {.name = "raw", },
285 .owner = THIS_MODULE,
286 };
288 static int __init raw_init(void)
289 {
290 dev_t dev = MKDEV(RAW_MAJOR, 0);
292 if (register_chrdev_region(dev, MAX_RAW_MINORS, "raw"))
293 goto error;
295 cdev_init(&raw_cdev, &raw_fops);
296 if (cdev_add(&raw_cdev, dev, MAX_RAW_MINORS)) {
297 kobject_put(&raw_cdev.kobj);
298 unregister_chrdev_region(dev, MAX_RAW_MINORS);
299 goto error;
300 }
302 raw_class = class_create(THIS_MODULE, "raw");
303 if (IS_ERR(raw_class)) {
304 printk(KERN_ERR "Error creating raw class.\n");
305 cdev_del(&raw_cdev);
306 unregister_chrdev_region(dev, MAX_RAW_MINORS);
307 goto error;
308 }
309 class_device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
311 return 0;
313 error:
314 printk(KERN_ERR "error register raw device\n");
315 return 1;
316 }
318 static void __exit raw_exit(void)
319 {
320 class_device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
321 class_destroy(raw_class);
322 cdev_del(&raw_cdev);
323 unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
324 }
326 module_init(raw_init);
327 module_exit(raw_exit);
328 MODULE_LICENSE("GPL");