Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 21 | #include <linux/mutex.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 22 | |
| 23 | #include <asm/uaccess.h> |
| 24 | |
| 25 | struct raw_device_data { |
| 26 | struct block_device *binding; |
| 27 | int inuse; |
| 28 | }; |
| 29 | |
gregkh@suse.de | ca8eca6 | 2005-03-23 09:53:09 -0800 | [diff] [blame] | 30 | static struct class *raw_class; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | static struct raw_device_data raw_devices[MAX_RAW_MINORS]; |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 32 | static DEFINE_MUTEX(raw_mutex); |
Arjan van de Ven | 62322d2 | 2006-07-03 00:24:21 -0700 | [diff] [blame] | 33 | static const struct file_operations raw_ctl_fops; /* forward declaration */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | |
| 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; |
| 50 | |
| 51 | if (minor == 0) { /* It is the control device */ |
| 52 | filp->f_op = &raw_ctl_fops; |
| 53 | return 0; |
| 54 | } |
| 55 | |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 56 | mutex_lock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | |
| 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) |
Josef Sipek | a7113a9 | 2006-12-08 02:36:55 -0800 | [diff] [blame^] | 78 | filp->f_path.dentry->d_inode->i_mapping = |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 79 | bdev->bd_inode->i_mapping; |
| 80 | filp->private_data = bdev; |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 81 | mutex_unlock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | return 0; |
| 83 | |
| 84 | out2: |
| 85 | bd_release(bdev); |
| 86 | out1: |
| 87 | blkdev_put(bdev); |
| 88 | out: |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 89 | mutex_unlock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | return err; |
| 91 | } |
| 92 | |
| 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; |
| 101 | |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 102 | mutex_lock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 109 | mutex_unlock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | |
| 111 | bd_release(bdev); |
| 112 | blkdev_put(bdev); |
| 113 | return 0; |
| 114 | } |
| 115 | |
| 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; |
| 124 | |
Stephen Tweedie | e72022e | 2005-05-18 11:22:31 -0400 | [diff] [blame] | 125 | return blkdev_ioctl(bdev->bd_inode, NULL, command, arg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | } |
| 127 | |
| 128 | static void bind_device(struct raw_config_request *rq) |
| 129 | { |
Greg Kroah-Hartman | 38ca6c3 | 2006-08-07 22:19:37 -0700 | [diff] [blame] | 130 | device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor)); |
| 131 | device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), |
| 132 | "raw%d", rq->raw_minor); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | } |
| 134 | |
| 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; |
| 145 | |
| 146 | switch (command) { |
| 147 | case RAW_SETBIND: |
| 148 | case RAW_GETBIND: |
| 149 | |
| 150 | /* First, find out which raw minor we want */ |
| 151 | |
| 152 | if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) { |
| 153 | err = -EFAULT; |
| 154 | goto out; |
| 155 | } |
| 156 | |
| 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]; |
| 162 | |
| 163 | if (command == RAW_SETBIND) { |
| 164 | dev_t dev; |
| 165 | |
| 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 | } |
| 174 | |
| 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 | */ |
| 181 | |
| 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 | } |
| 189 | |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 190 | mutex_lock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | if (rawdev->inuse) { |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 192 | mutex_unlock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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; |
Greg Kroah-Hartman | 38ca6c3 | 2006-08-07 22:19:37 -0700 | [diff] [blame] | 203 | device_destroy(raw_class, |
gregkh@suse.de | ca8eca6 | 2005-03-23 09:53:09 -0800 | [diff] [blame] | 204 | MKDEV(RAW_MAJOR, rq.raw_minor)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 214 | mutex_unlock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 215 | } else { |
| 216 | struct block_device *bdev; |
| 217 | |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 218 | mutex_lock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |
Arjan van de Ven | 8ed965d | 2006-03-23 03:00:21 -0800 | [diff] [blame] | 226 | mutex_unlock(&raw_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |
| 240 | |
Arjan van de Ven | 62322d2 | 2006-07-03 00:24:21 -0700 | [diff] [blame] | 241 | static const struct file_operations raw_fops = { |
Badari Pulavarty | 543ade1 | 2006-09-30 23:28:48 -0700 | [diff] [blame] | 242 | .read = do_sync_read, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 243 | .aio_read = generic_file_aio_read, |
Badari Pulavarty | 543ade1 | 2006-09-30 23:28:48 -0700 | [diff] [blame] | 244 | .write = do_sync_write, |
Badari Pulavarty | 027445c | 2006-09-30 23:28:46 -0700 | [diff] [blame] | 245 | .aio_write = generic_file_aio_write_nolock, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | .open = raw_open, |
| 247 | .release= raw_release, |
| 248 | .ioctl = raw_ioctl, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 249 | .owner = THIS_MODULE, |
| 250 | }; |
| 251 | |
Arjan van de Ven | 62322d2 | 2006-07-03 00:24:21 -0700 | [diff] [blame] | 252 | static const struct file_operations raw_ctl_fops = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 253 | .ioctl = raw_ctl_ioctl, |
| 254 | .open = raw_open, |
| 255 | .owner = THIS_MODULE, |
| 256 | }; |
| 257 | |
| 258 | static struct cdev raw_cdev = { |
| 259 | .kobj = {.name = "raw", }, |
| 260 | .owner = THIS_MODULE, |
| 261 | }; |
| 262 | |
| 263 | static int __init raw_init(void) |
| 264 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 265 | dev_t dev = MKDEV(RAW_MAJOR, 0); |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 266 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 268 | ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw"); |
| 269 | if (ret) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 270 | goto error; |
| 271 | |
| 272 | cdev_init(&raw_cdev, &raw_fops); |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 273 | ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS); |
| 274 | if (ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | kobject_put(&raw_cdev.kobj); |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 276 | goto error_region; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 277 | } |
| 278 | |
gregkh@suse.de | ca8eca6 | 2005-03-23 09:53:09 -0800 | [diff] [blame] | 279 | raw_class = class_create(THIS_MODULE, "raw"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 280 | if (IS_ERR(raw_class)) { |
| 281 | printk(KERN_ERR "Error creating raw class.\n"); |
| 282 | cdev_del(&raw_cdev); |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 283 | ret = PTR_ERR(raw_class); |
| 284 | goto error_region; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 285 | } |
Greg Kroah-Hartman | 38ca6c3 | 2006-08-07 22:19:37 -0700 | [diff] [blame] | 286 | device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), "rawctl"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 287 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 288 | return 0; |
| 289 | |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 290 | error_region: |
| 291 | unregister_chrdev_region(dev, MAX_RAW_MINORS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 292 | error: |
Rolf Eike Beer | 3e26a42 | 2006-09-29 02:00:46 -0700 | [diff] [blame] | 293 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 294 | } |
| 295 | |
| 296 | static void __exit raw_exit(void) |
| 297 | { |
Greg Kroah-Hartman | 38ca6c3 | 2006-08-07 22:19:37 -0700 | [diff] [blame] | 298 | device_destroy(raw_class, MKDEV(RAW_MAJOR, 0)); |
gregkh@suse.de | ca8eca6 | 2005-03-23 09:53:09 -0800 | [diff] [blame] | 299 | class_destroy(raw_class); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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"); |