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x86/PCI: use host bridge _CRS info on ASUS M2V-MX SE
[linux-btrfs-devel.git] / drivers / usb / core / inode.c
blob2278dad886e2e8b028b2809eb39ccba8c09dff46
1 /*****************************************************************************/
2
3 /*
4 * inode.c -- Inode/Dentry functions for the USB device file system.
5 *
6 * Copyright (C) 2000 Thomas Sailer (sailer@ife.ee.ethz.ch)
7 * Copyright (C) 2001,2002,2004 Greg Kroah-Hartman (greg@kroah.com)
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 *
23 * History:
24 * 0.1 04.01.2000 Created
25 * 0.2 10.12.2001 converted to use the vfs layer better
26 */
27
28 /*****************************************************************************/
29
30 #include <linux/module.h>
31 #include <linux/fs.h>
32 #include <linux/mount.h>
33 #include <linux/pagemap.h>
34 #include <linux/init.h>
35 #include <linux/proc_fs.h>
36 #include <linux/usb.h>
37 #include <linux/namei.h>
38 #include <linux/usbdevice_fs.h>
39 #include <linux/parser.h>
40 #include <linux/notifier.h>
41 #include <linux/seq_file.h>
42 #include <linux/usb/hcd.h>
43 #include <asm/byteorder.h>
44 #include "usb.h"
45
46 #define USBFS_DEFAULT_DEVMODE (S_IWUSR | S_IRUGO)
47 #define USBFS_DEFAULT_BUSMODE (S_IXUGO | S_IRUGO)
48 #define USBFS_DEFAULT_LISTMODE S_IRUGO
49
50 static const struct file_operations default_file_operations;
51 static struct vfsmount *usbfs_mount;
52 static int usbfs_mount_count; /* = 0 */
53 static int ignore_mount = 0;
54
55 static struct dentry *devices_usbfs_dentry;
56 static int num_buses; /* = 0 */
57
58 static uid_t devuid; /* = 0 */
59 static uid_t busuid; /* = 0 */
60 static uid_t listuid; /* = 0 */
61 static gid_t devgid; /* = 0 */
62 static gid_t busgid; /* = 0 */
63 static gid_t listgid; /* = 0 */
64 static umode_t devmode = USBFS_DEFAULT_DEVMODE;
65 static umode_t busmode = USBFS_DEFAULT_BUSMODE;
66 static umode_t listmode = USBFS_DEFAULT_LISTMODE;
67
68 static int usbfs_show_options(struct seq_file *seq, struct vfsmount *mnt)
69 {
70 if (devuid != 0)
71 seq_printf(seq, ",devuid=%u", devuid);
72 if (devgid != 0)
73 seq_printf(seq, ",devgid=%u", devgid);
74 if (devmode != USBFS_DEFAULT_DEVMODE)
75 seq_printf(seq, ",devmode=%o", devmode);
76 if (busuid != 0)
77 seq_printf(seq, ",busuid=%u", busuid);
78 if (busgid != 0)
79 seq_printf(seq, ",busgid=%u", busgid);
80 if (busmode != USBFS_DEFAULT_BUSMODE)
81 seq_printf(seq, ",busmode=%o", busmode);
82 if (listuid != 0)
83 seq_printf(seq, ",listuid=%u", listuid);
84 if (listgid != 0)
85 seq_printf(seq, ",listgid=%u", listgid);
86 if (listmode != USBFS_DEFAULT_LISTMODE)
87 seq_printf(seq, ",listmode=%o", listmode);
88
89 return 0;
90 }
91
92 enum {
93 Opt_devuid, Opt_devgid, Opt_devmode,
94 Opt_busuid, Opt_busgid, Opt_busmode,
95 Opt_listuid, Opt_listgid, Opt_listmode,
96 Opt_err,
97 };
98
99 static const match_table_t tokens = {
100 {Opt_devuid, "devuid=%u"},
101 {Opt_devgid, "devgid=%u"},
102 {Opt_devmode, "devmode=%o"},
103 {Opt_busuid, "busuid=%u"},
104 {Opt_busgid, "busgid=%u"},
105 {Opt_busmode, "busmode=%o"},
106 {Opt_listuid, "listuid=%u"},
107 {Opt_listgid, "listgid=%u"},
108 {Opt_listmode, "listmode=%o"},
109 {Opt_err, NULL}
110 };
111
112 static int parse_options(struct super_block *s, char *data)
113 {
114 char *p;
115 int option;
116
117 /* (re)set to defaults. */
118 devuid = 0;
119 busuid = 0;
120 listuid = 0;
121 devgid = 0;
122 busgid = 0;
123 listgid = 0;
124 devmode = USBFS_DEFAULT_DEVMODE;
125 busmode = USBFS_DEFAULT_BUSMODE;
126 listmode = USBFS_DEFAULT_LISTMODE;
127
128 while ((p = strsep(&data, ",")) != NULL) {
129 substring_t args[MAX_OPT_ARGS];
130 int token;
131 if (!*p)
132 continue;
133
134 token = match_token(p, tokens, args);
135 switch (token) {
136 case Opt_devuid:
137 if (match_int(&args[0], &option))
138 return -EINVAL;
139 devuid = option;
140 break;
141 case Opt_devgid:
142 if (match_int(&args[0], &option))
143 return -EINVAL;
144 devgid = option;
145 break;
146 case Opt_devmode:
147 if (match_octal(&args[0], &option))
148 return -EINVAL;
149 devmode = option & S_IRWXUGO;
150 break;
151 case Opt_busuid:
152 if (match_int(&args[0], &option))
153 return -EINVAL;
154 busuid = option;
155 break;
156 case Opt_busgid:
157 if (match_int(&args[0], &option))
158 return -EINVAL;
159 busgid = option;
160 break;
161 case Opt_busmode:
162 if (match_octal(&args[0], &option))
163 return -EINVAL;
164 busmode = option & S_IRWXUGO;
165 break;
166 case Opt_listuid:
167 if (match_int(&args[0], &option))
168 return -EINVAL;
169 listuid = option;
170 break;
171 case Opt_listgid:
172 if (match_int(&args[0], &option))
173 return -EINVAL;
174 listgid = option;
175 break;
176 case Opt_listmode:
177 if (match_octal(&args[0], &option))
178 return -EINVAL;
179 listmode = option & S_IRWXUGO;
180 break;
181 default:
182 printk(KERN_ERR "usbfs: unrecognised mount option "
183 "\"%s\" or missing value\n", p);
184 return -EINVAL;
185 }
186 }
187
188 return 0;
189 }
190
191 static void update_special(struct dentry *special)
192 {
193 special->d_inode->i_uid = listuid;
194 special->d_inode->i_gid = listgid;
195 special->d_inode->i_mode = S_IFREG | listmode;
196 }
197
198 static void update_dev(struct dentry *dev)
199 {
200 dev->d_inode->i_uid = devuid;
201 dev->d_inode->i_gid = devgid;
202 dev->d_inode->i_mode = S_IFREG | devmode;
203 }
204
205 static void update_bus(struct dentry *bus)
206 {
207 struct dentry *dev = NULL;
208
209 bus->d_inode->i_uid = busuid;
210 bus->d_inode->i_gid = busgid;
211 bus->d_inode->i_mode = S_IFDIR | busmode;
212
213 mutex_lock(&bus->d_inode->i_mutex);
214
215 list_for_each_entry(dev, &bus->d_subdirs, d_u.d_child)
216 if (dev->d_inode)
217 update_dev(dev);
218
219 mutex_unlock(&bus->d_inode->i_mutex);
220 }
221
222 static void update_sb(struct super_block *sb)
223 {
224 struct dentry *root = sb->s_root;
225 struct dentry *bus = NULL;
226
227 if (!root)
228 return;
229
230 mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_PARENT);
231
232 list_for_each_entry(bus, &root->d_subdirs, d_u.d_child) {
233 if (bus->d_inode) {
234 switch (S_IFMT & bus->d_inode->i_mode) {
235 case S_IFDIR:
236 update_bus(bus);
237 break;
238 case S_IFREG:
239 update_special(bus);
240 break;
241 default:
242 printk(KERN_WARNING "usbfs: Unknown node %s "
243 "mode %x found on remount!\n",
244 bus->d_name.name, bus->d_inode->i_mode);
245 break;
246 }
247 }
248 }
249
250 mutex_unlock(&root->d_inode->i_mutex);
251 }
252
253 static int remount(struct super_block *sb, int *flags, char *data)
254 {
255 /* If this is not a real mount,
256 * i.e. it's a simple_pin_fs from create_special_files,
257 * then ignore it.
258 */
259 if (ignore_mount)
260 return 0;
261
262 if (parse_options(sb, data)) {
263 printk(KERN_WARNING "usbfs: mount parameter error.\n");
264 return -EINVAL;
265 }
266
267 if (usbfs_mount && usbfs_mount->mnt_sb)
268 update_sb(usbfs_mount->mnt_sb);
269
270 return 0;
271 }
272
273 static struct inode *usbfs_get_inode (struct super_block *sb, int mode, dev_t dev)
274 {
275 struct inode *inode = new_inode(sb);
276
277 if (inode) {
278 inode->i_ino = get_next_ino();
279 inode->i_mode = mode;
280 inode->i_uid = current_fsuid();
281 inode->i_gid = current_fsgid();
282 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
283 switch (mode & S_IFMT) {
284 default:
285 init_special_inode(inode, mode, dev);
286 break;
287 case S_IFREG:
288 inode->i_fop = &default_file_operations;
289 break;
290 case S_IFDIR:
291 inode->i_op = &simple_dir_inode_operations;
292 inode->i_fop = &simple_dir_operations;
293
294 /* directory inodes start off with i_nlink == 2 (for "." entry) */
295 inc_nlink(inode);
296 break;
297 }
298 }
299 return inode;
300 }
301
302 /* SMP-safe */
303 static int usbfs_mknod (struct inode *dir, struct dentry *dentry, int mode,
304 dev_t dev)
305 {
306 struct inode *inode = usbfs_get_inode(dir->i_sb, mode, dev);
307 int error = -EPERM;
308
309 if (dentry->d_inode)
310 return -EEXIST;
311
312 if (inode) {
313 d_instantiate(dentry, inode);
314 dget(dentry);
315 error = 0;
316 }
317 return error;
318 }
319
320 static int usbfs_mkdir (struct inode *dir, struct dentry *dentry, int mode)
321 {
322 int res;
323
324 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
325 res = usbfs_mknod (dir, dentry, mode, 0);
326 if (!res)
327 inc_nlink(dir);
328 return res;
329 }
330
331 static int usbfs_create (struct inode *dir, struct dentry *dentry, int mode)
332 {
333 mode = (mode & S_IALLUGO) | S_IFREG;
334 return usbfs_mknod (dir, dentry, mode, 0);
335 }
336
337 static inline int usbfs_positive (struct dentry *dentry)
338 {
339 return dentry->d_inode && !d_unhashed(dentry);
340 }
341
342 static int usbfs_empty (struct dentry *dentry)
343 {
344 struct list_head *list;
345
346 spin_lock(&dentry->d_lock);
347 list_for_each(list, &dentry->d_subdirs) {
348 struct dentry *de = list_entry(list, struct dentry, d_u.d_child);
349
350 spin_lock_nested(&de->d_lock, DENTRY_D_LOCK_NESTED);
351 if (usbfs_positive(de)) {
352 spin_unlock(&de->d_lock);
353 spin_unlock(&dentry->d_lock);
354 return 0;
355 }
356 spin_unlock(&de->d_lock);
357 }
358 spin_unlock(&dentry->d_lock);
359 return 1;
360 }
361
362 static int usbfs_unlink (struct inode *dir, struct dentry *dentry)
363 {
364 struct inode *inode = dentry->d_inode;
365 mutex_lock(&inode->i_mutex);
366 drop_nlink(dentry->d_inode);
367 dput(dentry);
368 mutex_unlock(&inode->i_mutex);
369 d_delete(dentry);
370 return 0;
371 }
372
373 static int usbfs_rmdir(struct inode *dir, struct dentry *dentry)
374 {
375 int error = -ENOTEMPTY;
376 struct inode * inode = dentry->d_inode;
377
378 mutex_lock(&inode->i_mutex);
379 dentry_unhash(dentry);
380 if (usbfs_empty(dentry)) {
381 dont_mount(dentry);
382 drop_nlink(dentry->d_inode);
383 drop_nlink(dentry->d_inode);
384 dput(dentry);
385 inode->i_flags |= S_DEAD;
386 drop_nlink(dir);
387 error = 0;
388 }
389 mutex_unlock(&inode->i_mutex);
390 if (!error)
391 d_delete(dentry);
392 return error;
393 }
394
395
396 /* default file operations */
397 static ssize_t default_read_file (struct file *file, char __user *buf,
398 size_t count, loff_t *ppos)
399 {
400 return 0;
401 }
402
403 static ssize_t default_write_file (struct file *file, const char __user *buf,
404 size_t count, loff_t *ppos)
405 {
406 return count;
407 }
408
409 static loff_t default_file_lseek (struct file *file, loff_t offset, int orig)
410 {
411 loff_t retval = -EINVAL;
412
413 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
414 switch(orig) {
415 case 0:
416 if (offset > 0) {
417 file->f_pos = offset;
418 retval = file->f_pos;
419 }
420 break;
421 case 1:
422 if ((offset + file->f_pos) > 0) {
423 file->f_pos += offset;
424 retval = file->f_pos;
425 }
426 break;
427 default:
428 break;
429 }
430 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
431 return retval;
432 }
433
434 static int default_open (struct inode *inode, struct file *file)
435 {
436 if (inode->i_private)
437 file->private_data = inode->i_private;
438
439 return 0;
440 }
441
442 static const struct file_operations default_file_operations = {
443 .read = default_read_file,
444 .write = default_write_file,
445 .open = default_open,
446 .llseek = default_file_lseek,
447 };
448
449 static const struct super_operations usbfs_ops = {
450 .statfs = simple_statfs,
451 .drop_inode = generic_delete_inode,
452 .remount_fs = remount,
453 .show_options = usbfs_show_options,
454 };
455
456 static int usbfs_fill_super(struct super_block *sb, void *data, int silent)
457 {
458 struct inode *inode;
459 struct dentry *root;
460
461 sb->s_blocksize = PAGE_CACHE_SIZE;
462 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
463 sb->s_magic = USBDEVICE_SUPER_MAGIC;
464 sb->s_op = &usbfs_ops;
465 sb->s_time_gran = 1;
466 inode = usbfs_get_inode(sb, S_IFDIR | 0755, 0);
467
468 if (!inode) {
469 dbg("%s: could not get inode!",__func__);
470 return -ENOMEM;
471 }
472
473 root = d_alloc_root(inode);
474 if (!root) {
475 dbg("%s: could not get root dentry!",__func__);
476 iput(inode);
477 return -ENOMEM;
478 }
479 sb->s_root = root;
480 return 0;
481 }
482
483 /*
484 * fs_create_by_name - create a file, given a name
485 * @name: name of file
486 * @mode: type of file
487 * @parent: dentry of directory to create it in
488 * @dentry: resulting dentry of file
489 *
490 * This function handles both regular files and directories.
491 */
492 static int fs_create_by_name (const char *name, mode_t mode,
493 struct dentry *parent, struct dentry **dentry)
494 {
495 int error = 0;
496
497 /* If the parent is not specified, we create it in the root.
498 * We need the root dentry to do this, which is in the super
499 * block. A pointer to that is in the struct vfsmount that we
500 * have around.
501 */
502 if (!parent ) {
503 if (usbfs_mount && usbfs_mount->mnt_sb) {
504 parent = usbfs_mount->mnt_sb->s_root;
505 }
506 }
507
508 if (!parent) {
509 dbg("Ah! can not find a parent!");
510 return -EFAULT;
511 }
512
513 *dentry = NULL;
514 mutex_lock(&parent->d_inode->i_mutex);
515 *dentry = lookup_one_len(name, parent, strlen(name));
516 if (!IS_ERR(*dentry)) {
517 if ((mode & S_IFMT) == S_IFDIR)
518 error = usbfs_mkdir (parent->d_inode, *dentry, mode);
519 else
520 error = usbfs_create (parent->d_inode, *dentry, mode);
521 } else
522 error = PTR_ERR(*dentry);
523 mutex_unlock(&parent->d_inode->i_mutex);
524
525 return error;
526 }
527
528 static struct dentry *fs_create_file (const char *name, mode_t mode,
529 struct dentry *parent, void *data,
530 const struct file_operations *fops,
531 uid_t uid, gid_t gid)
532 {
533 struct dentry *dentry;
534 int error;
535
536 dbg("creating file '%s'",name);
537
538 error = fs_create_by_name (name, mode, parent, &dentry);
539 if (error) {
540 dentry = NULL;
541 } else {
542 if (dentry->d_inode) {
543 if (data)
544 dentry->d_inode->i_private = data;
545 if (fops)
546 dentry->d_inode->i_fop = fops;
547 dentry->d_inode->i_uid = uid;
548 dentry->d_inode->i_gid = gid;
549 }
550 }
551
552 return dentry;
553 }
554
555 static void fs_remove_file (struct dentry *dentry)
556 {
557 struct dentry *parent = dentry->d_parent;
558
559 if (!parent || !parent->d_inode)
560 return;
561
562 mutex_lock_nested(&parent->d_inode->i_mutex, I_MUTEX_PARENT);
563 if (usbfs_positive(dentry)) {
564 if (dentry->d_inode) {
565 if (S_ISDIR(dentry->d_inode->i_mode))
566 usbfs_rmdir(parent->d_inode, dentry);
567 else
568 usbfs_unlink(parent->d_inode, dentry);
569 dput(dentry);
570 }
571 }
572 mutex_unlock(&parent->d_inode->i_mutex);
573 }
574
575 /* --------------------------------------------------------------------- */
576
577 static struct dentry *usb_mount(struct file_system_type *fs_type,
578 int flags, const char *dev_name, void *data)
579 {
580 return mount_single(fs_type, flags, data, usbfs_fill_super);
581 }
582
583 static struct file_system_type usb_fs_type = {
584 .owner = THIS_MODULE,
585 .name = "usbfs",
586 .mount = usb_mount,
587 .kill_sb = kill_litter_super,
588 };
589
590 /* --------------------------------------------------------------------- */
591
592 static int create_special_files (void)
593 {
594 struct dentry *parent;
595 int retval;
596
597 /* the simple_pin_fs calls will call remount with no options
598 * without this flag that would overwrite the real mount options (if any)
599 */
600 ignore_mount = 1;
601
602 /* create the devices special file */
603 retval = simple_pin_fs(&usb_fs_type, &usbfs_mount, &usbfs_mount_count);
604 if (retval) {
605 printk(KERN_ERR "Unable to get usbfs mount\n");
606 goto exit;
607 }
608
609 ignore_mount = 0;
610
611 parent = usbfs_mount->mnt_sb->s_root;
612 devices_usbfs_dentry = fs_create_file ("devices",
613 listmode | S_IFREG, parent,
614 NULL, &usbfs_devices_fops,
615 listuid, listgid);
616 if (devices_usbfs_dentry == NULL) {
617 printk(KERN_ERR "Unable to create devices usbfs file\n");
618 retval = -ENODEV;
619 goto error_clean_mounts;
620 }
621
622 goto exit;
623
624 error_clean_mounts:
625 simple_release_fs(&usbfs_mount, &usbfs_mount_count);
626 exit:
627 return retval;
628 }
629
630 static void remove_special_files (void)
631 {
632 if (devices_usbfs_dentry)
633 fs_remove_file (devices_usbfs_dentry);
634 devices_usbfs_dentry = NULL;
635 simple_release_fs(&usbfs_mount, &usbfs_mount_count);
636 }
637
638 void usbfs_update_special (void)
639 {
640 struct inode *inode;
641
642 if (devices_usbfs_dentry) {
643 inode = devices_usbfs_dentry->d_inode;
644 if (inode)
645 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
646 }
647 }
648
649 static void usbfs_add_bus(struct usb_bus *bus)
650 {
651 struct dentry *parent;
652 char name[8];
653 int retval;
654
655 /* create the special files if this is the first bus added */
656 if (num_buses == 0) {
657 retval = create_special_files();
658 if (retval)
659 return;
660 }
661 ++num_buses;
662
663 sprintf (name, "%03d", bus->busnum);
664
665 parent = usbfs_mount->mnt_sb->s_root;
666 bus->usbfs_dentry = fs_create_file (name, busmode | S_IFDIR, parent,
667 bus, NULL, busuid, busgid);
668 if (bus->usbfs_dentry == NULL) {
669 printk(KERN_ERR "Error creating usbfs bus entry\n");
670 return;
671 }
672 }
673
674 static void usbfs_remove_bus(struct usb_bus *bus)
675 {
676 if (bus->usbfs_dentry) {
677 fs_remove_file (bus->usbfs_dentry);
678 bus->usbfs_dentry = NULL;
679 }
680
681 --num_buses;
682 if (num_buses <= 0) {
683 remove_special_files();
684 num_buses = 0;
685 }
686 }
687
688 static void usbfs_add_device(struct usb_device *dev)
689 {
690 char name[8];
691 int i;
692 int i_size;
693
694 sprintf (name, "%03d", dev->devnum);
695 dev->usbfs_dentry = fs_create_file (name, devmode | S_IFREG,
696 dev->bus->usbfs_dentry, dev,
697 &usbdev_file_operations,
698 devuid, devgid);
699 if (dev->usbfs_dentry == NULL) {
700 printk(KERN_ERR "Error creating usbfs device entry\n");
701 return;
702 }
703
704 /* Set the size of the device's file to be
705 * equal to the size of the device descriptors. */
706 i_size = sizeof (struct usb_device_descriptor);
707 for (i = 0; i < dev->descriptor.bNumConfigurations; ++i) {
708 struct usb_config_descriptor *config =
709 (struct usb_config_descriptor *)dev->rawdescriptors[i];
710 i_size += le16_to_cpu(config->wTotalLength);
711 }
712 if (dev->usbfs_dentry->d_inode)
713 dev->usbfs_dentry->d_inode->i_size = i_size;
714 }
715
716 static void usbfs_remove_device(struct usb_device *dev)
717 {
718 if (dev->usbfs_dentry) {
719 fs_remove_file (dev->usbfs_dentry);
720 dev->usbfs_dentry = NULL;
721 }
722 }
723
724 static int usbfs_notify(struct notifier_block *self, unsigned long action, void *dev)
725 {
726 switch (action) {
727 case USB_DEVICE_ADD:
728 usbfs_add_device(dev);
729 break;
730 case USB_DEVICE_REMOVE:
731 usbfs_remove_device(dev);
732 break;
733 case USB_BUS_ADD:
734 usbfs_add_bus(dev);
735 break;
736 case USB_BUS_REMOVE:
737 usbfs_remove_bus(dev);
738 }
739
740 usbfs_update_special();
741 usbfs_conn_disc_event();
742 return NOTIFY_OK;
743 }
744
745 static struct notifier_block usbfs_nb = {
746 .notifier_call = usbfs_notify,
747 };
748
749 /* --------------------------------------------------------------------- */
750
751 static struct proc_dir_entry *usbdir = NULL;
752
753 int __init usbfs_init(void)
754 {
755 int retval;
756
757 retval = register_filesystem(&usb_fs_type);
758 if (retval)
759 return retval;
760
761 usb_register_notify(&usbfs_nb);
762
763 /* create mount point for usbfs */
764 usbdir = proc_mkdir("bus/usb", NULL);
765
766 return 0;
767 }
768
769 void usbfs_cleanup(void)
770 {
771 usb_unregister_notify(&usbfs_nb);
772 unregister_filesystem(&usb_fs_type);
773 if (usbdir)
774 remove_proc_entry("bus/usb", NULL);
775 }
776
Linux Btrfs Development