blob: a173551e19d79da5ae6132be9eaa24522abd4580 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/char_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/init.h>
8#include <linux/fs.h>
Andrew Mortonb446b602007-02-20 13:57:48 -08009#include <linux/kdev_t.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/slab.h>
11#include <linux/string.h>
12
13#include <linux/major.h>
14#include <linux/errno.h>
15#include <linux/module.h>
Joe Korty68eef3b2006-03-31 02:30:32 -080016#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
18#include <linux/kobject.h>
19#include <linux/kobj_map.h>
20#include <linux/cdev.h>
Jes Sorensen58383af2006-02-06 14:12:43 -080021#include <linux/mutex.h>
David Howells5da61852006-09-27 01:50:16 -070022#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
David Howells07f3f052006-09-30 20:52:18 +020024#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
David Howells5da61852006-09-27 01:50:16 -070026/*
27 * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
28 * devices
29 * - permits shared-mmap for read, write and/or exec
30 * - does not permit private mmap in NOMMU mode (can't do COW)
31 * - no readahead or I/O queue unplugging required
32 */
33struct backing_dev_info directly_mappable_cdev_bdi = {
34 .capabilities = (
35#ifdef CONFIG_MMU
36 /* permit private copies of the data to be taken */
37 BDI_CAP_MAP_COPY |
38#endif
39 /* permit direct mmap, for read, write or exec */
40 BDI_CAP_MAP_DIRECT |
41 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
42};
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044static struct kobj_map *cdev_map;
45
Jes Sorensen58383af2006-02-06 14:12:43 -080046static DEFINE_MUTEX(chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48static struct char_device_struct {
49 struct char_device_struct *next;
50 unsigned int major;
51 unsigned int baseminor;
52 int minorct;
Neil Horman7170be52006-01-14 13:20:38 -080053 char name[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 struct cdev *cdev; /* will die */
Joe Korty68eef3b2006-03-31 02:30:32 -080055} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57/* index in the above */
58static inline int major_to_index(int major)
59{
Joe Korty68eef3b2006-03-31 02:30:32 -080060 return major % CHRDEV_MAJOR_HASH_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061}
62
Joe Korty68eef3b2006-03-31 02:30:32 -080063#ifdef CONFIG_PROC_FS
Neil Horman7170be52006-01-14 13:20:38 -080064
Joe Korty68eef3b2006-03-31 02:30:32 -080065void chrdev_show(struct seq_file *f, off_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -070066{
67 struct char_device_struct *cd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
Joe Korty68eef3b2006-03-31 02:30:32 -080069 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
70 mutex_lock(&chrdevs_lock);
71 for (cd = chrdevs[offset]; cd; cd = cd->next)
72 seq_printf(f, "%3d %s\n", cd->major, cd->name);
73 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 }
Neil Horman7170be52006-01-14 13:20:38 -080075}
76
Joe Korty68eef3b2006-03-31 02:30:32 -080077#endif /* CONFIG_PROC_FS */
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
79/*
80 * Register a single major with a specified minor range.
81 *
82 * If major == 0 this functions will dynamically allocate a major and return
83 * its number.
84 *
85 * If major > 0 this function will attempt to reserve the passed range of
86 * minors and will return zero on success.
87 *
88 * Returns a -ve errno on failure.
89 */
90static struct char_device_struct *
91__register_chrdev_region(unsigned int major, unsigned int baseminor,
92 int minorct, const char *name)
93{
94 struct char_device_struct *cd, **cp;
95 int ret = 0;
96 int i;
97
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080098 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 if (cd == NULL)
100 return ERR_PTR(-ENOMEM);
101
Jes Sorensen58383af2006-02-06 14:12:43 -0800102 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103
104 /* temporary */
105 if (major == 0) {
106 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
107 if (chrdevs[i] == NULL)
108 break;
109 }
110
111 if (i == 0) {
112 ret = -EBUSY;
113 goto out;
114 }
115 major = i;
116 ret = major;
117 }
118
119 cd->major = major;
120 cd->baseminor = baseminor;
121 cd->minorct = minorct;
Cyrill Gorcunov8c401882009-01-06 14:41:08 -0800122 strlcpy(cd->name, name, sizeof(cd->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
124 i = major_to_index(major);
125
126 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
127 if ((*cp)->major > major ||
Amos Waterland01d553d2006-09-29 02:00:08 -0700128 ((*cp)->major == major &&
129 (((*cp)->baseminor >= baseminor) ||
130 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 break;
Amos Waterland01d553d2006-09-29 02:00:08 -0700132
133 /* Check for overlapping minor ranges. */
134 if (*cp && (*cp)->major == major) {
135 int old_min = (*cp)->baseminor;
136 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
137 int new_min = baseminor;
138 int new_max = baseminor + minorct - 1;
139
140 /* New driver overlaps from the left. */
141 if (new_max >= old_min && new_max <= old_max) {
142 ret = -EBUSY;
143 goto out;
144 }
145
146 /* New driver overlaps from the right. */
147 if (new_min <= old_max && new_min >= old_min) {
148 ret = -EBUSY;
149 goto out;
150 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 }
Amos Waterland01d553d2006-09-29 02:00:08 -0700152
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 cd->next = *cp;
154 *cp = cd;
Jes Sorensen58383af2006-02-06 14:12:43 -0800155 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 return cd;
157out:
Jes Sorensen58383af2006-02-06 14:12:43 -0800158 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 kfree(cd);
160 return ERR_PTR(ret);
161}
162
163static struct char_device_struct *
164__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
165{
166 struct char_device_struct *cd = NULL, **cp;
167 int i = major_to_index(major);
168
Jes Sorensen58383af2006-02-06 14:12:43 -0800169 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
171 if ((*cp)->major == major &&
172 (*cp)->baseminor == baseminor &&
173 (*cp)->minorct == minorct)
174 break;
175 if (*cp) {
176 cd = *cp;
177 *cp = cd->next;
178 }
Jes Sorensen58383af2006-02-06 14:12:43 -0800179 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 return cd;
181}
182
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700183/**
184 * register_chrdev_region() - register a range of device numbers
185 * @from: the first in the desired range of device numbers; must include
186 * the major number.
187 * @count: the number of consecutive device numbers required
188 * @name: the name of the device or driver.
189 *
190 * Return value is zero on success, a negative error code on failure.
191 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192int register_chrdev_region(dev_t from, unsigned count, const char *name)
193{
194 struct char_device_struct *cd;
195 dev_t to = from + count;
196 dev_t n, next;
197
198 for (n = from; n < to; n = next) {
199 next = MKDEV(MAJOR(n)+1, 0);
200 if (next > to)
201 next = to;
202 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
203 next - n, name);
204 if (IS_ERR(cd))
205 goto fail;
206 }
207 return 0;
208fail:
209 to = n;
210 for (n = from; n < to; n = next) {
211 next = MKDEV(MAJOR(n)+1, 0);
212 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
213 }
214 return PTR_ERR(cd);
215}
216
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700217/**
218 * alloc_chrdev_region() - register a range of char device numbers
219 * @dev: output parameter for first assigned number
220 * @baseminor: first of the requested range of minor numbers
221 * @count: the number of minor numbers required
222 * @name: the name of the associated device or driver
223 *
224 * Allocates a range of char device numbers. The major number will be
225 * chosen dynamically, and returned (along with the first minor number)
226 * in @dev. Returns zero or a negative error code.
227 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
229 const char *name)
230{
231 struct char_device_struct *cd;
232 cd = __register_chrdev_region(0, baseminor, count, name);
233 if (IS_ERR(cd))
234 return PTR_ERR(cd);
235 *dev = MKDEV(cd->major, cd->baseminor);
236 return 0;
237}
238
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700239/**
240 * register_chrdev() - Register a major number for character devices.
241 * @major: major device number or 0 for dynamic allocation
242 * @name: name of this range of devices
243 * @fops: file operations associated with this devices
244 *
245 * If @major == 0 this functions will dynamically allocate a major and return
246 * its number.
247 *
248 * If @major > 0 this function will attempt to reserve a device with the given
249 * major number and will return zero on success.
250 *
251 * Returns a -ve errno on failure.
252 *
253 * The name of this device has nothing to do with the name of the device in
254 * /dev. It only helps to keep track of the different owners of devices. If
255 * your module name has only one type of devices it's ok to use e.g. the name
256 * of the module here.
257 *
258 * This function registers a range of 256 minor numbers. The first minor number
259 * is 0.
260 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261int register_chrdev(unsigned int major, const char *name,
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800262 const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263{
264 struct char_device_struct *cd;
265 struct cdev *cdev;
266 char *s;
267 int err = -ENOMEM;
268
269 cd = __register_chrdev_region(major, 0, 256, name);
270 if (IS_ERR(cd))
271 return PTR_ERR(cd);
272
273 cdev = cdev_alloc();
274 if (!cdev)
275 goto out2;
276
277 cdev->owner = fops->owner;
278 cdev->ops = fops;
279 kobject_set_name(&cdev->kobj, "%s", name);
280 for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
281 *s = '!';
282
283 err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
284 if (err)
285 goto out;
286
287 cd->cdev = cdev;
288
289 return major ? 0 : cd->major;
290out:
291 kobject_put(&cdev->kobj);
292out2:
293 kfree(__unregister_chrdev_region(cd->major, 0, 256));
294 return err;
295}
296
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700297/**
298 * unregister_chrdev_region() - return a range of device numbers
299 * @from: the first in the range of numbers to unregister
300 * @count: the number of device numbers to unregister
301 *
302 * This function will unregister a range of @count device numbers,
303 * starting with @from. The caller should normally be the one who
304 * allocated those numbers in the first place...
305 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306void unregister_chrdev_region(dev_t from, unsigned count)
307{
308 dev_t to = from + count;
309 dev_t n, next;
310
311 for (n = from; n < to; n = next) {
312 next = MKDEV(MAJOR(n)+1, 0);
313 if (next > to)
314 next = to;
315 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
316 }
317}
318
Akinobu Mitae53252d2007-07-19 01:47:51 -0700319void unregister_chrdev(unsigned int major, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320{
321 struct char_device_struct *cd;
322 cd = __unregister_chrdev_region(major, 0, 256);
323 if (cd && cd->cdev)
324 cdev_del(cd->cdev);
325 kfree(cd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326}
327
328static DEFINE_SPINLOCK(cdev_lock);
329
330static struct kobject *cdev_get(struct cdev *p)
331{
332 struct module *owner = p->owner;
333 struct kobject *kobj;
334
335 if (owner && !try_module_get(owner))
336 return NULL;
337 kobj = kobject_get(&p->kobj);
338 if (!kobj)
339 module_put(owner);
340 return kobj;
341}
342
343void cdev_put(struct cdev *p)
344{
345 if (p) {
Brian King7da68442005-07-12 13:58:30 -0700346 struct module *owner = p->owner;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 kobject_put(&p->kobj);
Brian King7da68442005-07-12 13:58:30 -0700348 module_put(owner);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 }
350}
351
352/*
353 * Called every time a character special file is opened
354 */
Denis Cheng922f9cf2008-02-08 04:22:00 -0800355static int chrdev_open(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356{
357 struct cdev *p;
358 struct cdev *new = NULL;
359 int ret = 0;
360
361 spin_lock(&cdev_lock);
362 p = inode->i_cdev;
363 if (!p) {
364 struct kobject *kobj;
365 int idx;
366 spin_unlock(&cdev_lock);
367 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
368 if (!kobj)
369 return -ENXIO;
370 new = container_of(kobj, struct cdev, kobj);
371 spin_lock(&cdev_lock);
Jonathan Corbeta30427d2008-05-18 15:39:11 -0600372 /* Check i_cdev again in case somebody beat us to it while
373 we dropped the lock. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 p = inode->i_cdev;
375 if (!p) {
376 inode->i_cdev = p = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 list_add(&inode->i_devices, &p->list);
378 new = NULL;
379 } else if (!cdev_get(p))
380 ret = -ENXIO;
381 } else if (!cdev_get(p))
382 ret = -ENXIO;
383 spin_unlock(&cdev_lock);
384 cdev_put(new);
385 if (ret)
386 return ret;
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200387
388 ret = -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 filp->f_op = fops_get(p->ops);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200390 if (!filp->f_op)
391 goto out_cdev_put;
392
393 if (filp->f_op->open) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 ret = filp->f_op->open(inode,filp);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200395 if (ret)
396 goto out_cdev_put;
397 }
398
399 return 0;
400
401 out_cdev_put:
402 cdev_put(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 return ret;
404}
405
Theodore Ts'o9fd57462009-05-21 16:01:00 -0400406int cdev_index(struct inode *inode)
407{
408 int idx;
409 struct kobject *kobj;
410
411 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
412 if (!kobj)
413 return -1;
414 kobject_put(kobj);
415 return idx;
416}
417
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418void cd_forget(struct inode *inode)
419{
420 spin_lock(&cdev_lock);
421 list_del_init(&inode->i_devices);
422 inode->i_cdev = NULL;
423 spin_unlock(&cdev_lock);
424}
425
Adrian Bunk75c96f82005-05-05 16:16:09 -0700426static void cdev_purge(struct cdev *cdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427{
428 spin_lock(&cdev_lock);
429 while (!list_empty(&cdev->list)) {
430 struct inode *inode;
431 inode = container_of(cdev->list.next, struct inode, i_devices);
432 list_del_init(&inode->i_devices);
433 inode->i_cdev = NULL;
434 }
435 spin_unlock(&cdev_lock);
436}
437
438/*
439 * Dummy default file-operations: the only thing this does
440 * is contain the open that then fills in the correct operations
441 * depending on the special file...
442 */
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800443const struct file_operations def_chr_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 .open = chrdev_open,
445};
446
447static struct kobject *exact_match(dev_t dev, int *part, void *data)
448{
449 struct cdev *p = data;
450 return &p->kobj;
451}
452
453static int exact_lock(dev_t dev, void *data)
454{
455 struct cdev *p = data;
456 return cdev_get(p) ? 0 : -1;
457}
458
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700459/**
460 * cdev_add() - add a char device to the system
461 * @p: the cdev structure for the device
462 * @dev: the first device number for which this device is responsible
463 * @count: the number of consecutive minor numbers corresponding to this
464 * device
465 *
466 * cdev_add() adds the device represented by @p to the system, making it
467 * live immediately. A negative error code is returned on failure.
468 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469int cdev_add(struct cdev *p, dev_t dev, unsigned count)
470{
471 p->dev = dev;
472 p->count = count;
473 return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
474}
475
476static void cdev_unmap(dev_t dev, unsigned count)
477{
478 kobj_unmap(cdev_map, dev, count);
479}
480
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700481/**
482 * cdev_del() - remove a cdev from the system
483 * @p: the cdev structure to be removed
484 *
485 * cdev_del() removes @p from the system, possibly freeing the structure
486 * itself.
487 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488void cdev_del(struct cdev *p)
489{
490 cdev_unmap(p->dev, p->count);
491 kobject_put(&p->kobj);
492}
493
494
495static void cdev_default_release(struct kobject *kobj)
496{
497 struct cdev *p = container_of(kobj, struct cdev, kobj);
498 cdev_purge(p);
499}
500
501static void cdev_dynamic_release(struct kobject *kobj)
502{
503 struct cdev *p = container_of(kobj, struct cdev, kobj);
504 cdev_purge(p);
505 kfree(p);
506}
507
508static struct kobj_type ktype_cdev_default = {
509 .release = cdev_default_release,
510};
511
512static struct kobj_type ktype_cdev_dynamic = {
513 .release = cdev_dynamic_release,
514};
515
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700516/**
517 * cdev_alloc() - allocate a cdev structure
518 *
519 * Allocates and returns a cdev structure, or NULL on failure.
520 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521struct cdev *cdev_alloc(void)
522{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800523 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 if (p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 INIT_LIST_HEAD(&p->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700526 kobject_init(&p->kobj, &ktype_cdev_dynamic);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 }
528 return p;
529}
530
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700531/**
532 * cdev_init() - initialize a cdev structure
533 * @cdev: the structure to initialize
534 * @fops: the file_operations for this device
535 *
536 * Initializes @cdev, remembering @fops, making it ready to add to the
537 * system with cdev_add().
538 */
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800539void cdev_init(struct cdev *cdev, const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540{
541 memset(cdev, 0, sizeof *cdev);
542 INIT_LIST_HEAD(&cdev->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700543 kobject_init(&cdev->kobj, &ktype_cdev_default);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 cdev->ops = fops;
545}
546
547static struct kobject *base_probe(dev_t dev, int *part, void *data)
548{
549 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
550 /* Make old-style 2.4 aliases work */
551 request_module("char-major-%d", MAJOR(dev));
552 return NULL;
553}
554
555void __init chrdev_init(void)
556{
557 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700558 bdi_init(&directly_mappable_cdev_bdi);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559}
560
561
562/* Let modules do char dev stuff */
563EXPORT_SYMBOL(register_chrdev_region);
564EXPORT_SYMBOL(unregister_chrdev_region);
565EXPORT_SYMBOL(alloc_chrdev_region);
566EXPORT_SYMBOL(cdev_init);
567EXPORT_SYMBOL(cdev_alloc);
568EXPORT_SYMBOL(cdev_del);
569EXPORT_SYMBOL(cdev_add);
Theodore Ts'o9fd57462009-05-21 16:01:00 -0400570EXPORT_SYMBOL(cdev_index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571EXPORT_SYMBOL(register_chrdev);
572EXPORT_SYMBOL(unregister_chrdev);
David Howells5da61852006-09-27 01:50:16 -0700573EXPORT_SYMBOL(directly_mappable_cdev_bdi);