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1 /* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * dir.c - Operations for configfs directories.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public
17 * License along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA.
20 *
21 * Based on sysfs:
22 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
23 *
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
25 */
26
27 #undef DEBUG
28
29 #include <linux/fs.h>
30 #include <linux/mount.h>
31 #include <linux/module.h>
32 #include <linux/slab.h>
33 #include <linux/err.h>
34
35 #include <linux/configfs.h>
36 #include "configfs_internal.h"
37
38 DECLARE_RWSEM(configfs_rename_sem);
39 /*
40 * Protects mutations of configfs_dirent linkage together with proper i_mutex
41 * Also protects mutations of symlinks linkage to target configfs_dirent
42 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
43 * and configfs_dirent_lock locked, in that order.
44 * This allows one to safely traverse configfs_dirent trees and symlinks without
45 * having to lock inodes.
46 *
47 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
48 * unlocked is not reliable unless in detach_groups() called from
49 * rmdir()/unregister() and from configfs_attach_group()
50 */
51 DEFINE_SPINLOCK(configfs_dirent_lock);
52
53 static void configfs_d_iput(struct dentry * dentry,
54 struct inode * inode)
55 {
56 struct configfs_dirent *sd = dentry->d_fsdata;
57
58 if (sd) {
59 /* Coordinate with configfs_readdir */
60 spin_lock(&configfs_dirent_lock);
61 /* Coordinate with configfs_attach_attr where will increase
62 * sd->s_count and update sd->s_dentry to new allocated one.
63 * Only set sd->dentry to null when this dentry is the only
64 * sd owner.
65 * If not do so, configfs_d_iput may run just after
66 * configfs_attach_attr and set sd->s_dentry to null
67 * even it's still in use.
68 */
69 if (atomic_read(&sd->s_count) <= 2)
70 sd->s_dentry = NULL;
71
72 spin_unlock(&configfs_dirent_lock);
73 configfs_put(sd);
74 }
75 iput(inode);
76 }
77
78 const struct dentry_operations configfs_dentry_ops = {
79 .d_iput = configfs_d_iput,
80 .d_delete = always_delete_dentry,
81 };
82
83 #ifdef CONFIG_LOCKDEP
84
85 /*
86 * Helpers to make lockdep happy with our recursive locking of default groups'
87 * inodes (see configfs_attach_group() and configfs_detach_group()).
88 * We put default groups i_mutexes in separate classes according to their depth
89 * from the youngest non-default group ancestor.
90 *
91 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
92 * groups A/B and A/C will have their inode's mutex in class
93 * default_group_class[0], and default group A/C/D will be in
94 * default_group_class[1].
95 *
96 * The lock classes are declared and assigned in inode.c, according to the
97 * s_depth value.
98 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
99 * default groups, and reset to -1 when all default groups are attached. During
100 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
101 * inode's mutex is set to default_group_class[s_depth - 1].
102 */
103
104 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
105 {
106 sd->s_depth = -1;
107 }
108
109 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
110 struct configfs_dirent *sd)
111 {
112 int parent_depth = parent_sd->s_depth;
113
114 if (parent_depth >= 0)
115 sd->s_depth = parent_depth + 1;
116 }
117
118 static void
119 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
120 {
121 /*
122 * item's i_mutex class is already setup, so s_depth is now only
123 * used to set new sub-directories s_depth, which is always done
124 * with item's i_mutex locked.
125 */
126 /*
127 * sd->s_depth == -1 iff we are a non default group.
128 * else (we are a default group) sd->s_depth > 0 (see
129 * create_dir()).
130 */
131 if (sd->s_depth == -1)
132 /*
133 * We are a non default group and we are going to create
134 * default groups.
135 */
136 sd->s_depth = 0;
137 }
138
139 static void
140 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
141 {
142 /* We will not create default groups anymore. */
143 sd->s_depth = -1;
144 }
145
146 #else /* CONFIG_LOCKDEP */
147
148 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
149 {
150 }
151
152 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
153 struct configfs_dirent *sd)
154 {
155 }
156
157 static void
158 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
159 {
160 }
161
162 static void
163 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
164 {
165 }
166
167 #endif /* CONFIG_LOCKDEP */
168
169 /*
170 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
171 */
172 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
173 void *element, int type)
174 {
175 struct configfs_dirent * sd;
176
177 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
178 if (!sd)
179 return ERR_PTR(-ENOMEM);
180
181 atomic_set(&sd->s_count, 1);
182 INIT_LIST_HEAD(&sd->s_links);
183 INIT_LIST_HEAD(&sd->s_children);
184 sd->s_element = element;
185 sd->s_type = type;
186 configfs_init_dirent_depth(sd);
187 spin_lock(&configfs_dirent_lock);
188 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
189 spin_unlock(&configfs_dirent_lock);
190 kmem_cache_free(configfs_dir_cachep, sd);
191 return ERR_PTR(-ENOENT);
192 }
193 list_add(&sd->s_sibling, &parent_sd->s_children);
194 spin_unlock(&configfs_dirent_lock);
195
196 return sd;
197 }
198
199 /*
200 *
201 * Return -EEXIST if there is already a configfs element with the same
202 * name for the same parent.
203 *
204 * called with parent inode's i_mutex held
205 */
206 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
207 const unsigned char *new)
208 {
209 struct configfs_dirent * sd;
210
211 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
212 if (sd->s_element) {
213 const unsigned char *existing = configfs_get_name(sd);
214 if (strcmp(existing, new))
215 continue;
216 else
217 return -EEXIST;
218 }
219 }
220
221 return 0;
222 }
223
224
225 int configfs_make_dirent(struct configfs_dirent * parent_sd,
226 struct dentry * dentry, void * element,
227 umode_t mode, int type)
228 {
229 struct configfs_dirent * sd;
230
231 sd = configfs_new_dirent(parent_sd, element, type);
232 if (IS_ERR(sd))
233 return PTR_ERR(sd);
234
235 sd->s_mode = mode;
236 sd->s_dentry = dentry;
237 if (dentry)
238 dentry->d_fsdata = configfs_get(sd);
239
240 return 0;
241 }
242
243 static void init_dir(struct inode * inode)
244 {
245 inode->i_op = &configfs_dir_inode_operations;
246 inode->i_fop = &configfs_dir_operations;
247
248 /* directory inodes start off with i_nlink == 2 (for "." entry) */
249 inc_nlink(inode);
250 }
251
252 static void configfs_init_file(struct inode * inode)
253 {
254 inode->i_size = PAGE_SIZE;
255 inode->i_fop = &configfs_file_operations;
256 }
257
258 static void configfs_init_bin_file(struct inode *inode)
259 {
260 inode->i_size = 0;
261 inode->i_fop = &configfs_bin_file_operations;
262 }
263
264 static void init_symlink(struct inode * inode)
265 {
266 inode->i_op = &configfs_symlink_inode_operations;
267 }
268
269 /**
270 * configfs_create_dir - create a directory for an config_item.
271 * @item: config_itemwe're creating directory for.
272 * @dentry: config_item's dentry.
273 *
274 * Note: user-created entries won't be allowed under this new directory
275 * until it is validated by configfs_dir_set_ready()
276 */
277
278 static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
279 {
280 int error;
281 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
282 struct dentry *p = dentry->d_parent;
283
284 BUG_ON(!item);
285
286 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
287 if (unlikely(error))
288 return error;
289
290 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
291 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
292 if (unlikely(error))
293 return error;
294
295 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
296 error = configfs_create(dentry, mode, init_dir);
297 if (!error) {
298 inc_nlink(d_inode(p));
299 item->ci_dentry = dentry;
300 } else {
301 struct configfs_dirent *sd = dentry->d_fsdata;
302 if (sd) {
303 spin_lock(&configfs_dirent_lock);
304 list_del_init(&sd->s_sibling);
305 spin_unlock(&configfs_dirent_lock);
306 configfs_put(sd);
307 }
308 }
309 return error;
310 }
311
312 /*
313 * Allow userspace to create new entries under a new directory created with
314 * configfs_create_dir(), and under all of its chidlren directories recursively.
315 * @sd configfs_dirent of the new directory to validate
316 *
317 * Caller must hold configfs_dirent_lock.
318 */
319 static void configfs_dir_set_ready(struct configfs_dirent *sd)
320 {
321 struct configfs_dirent *child_sd;
322
323 sd->s_type &= ~CONFIGFS_USET_CREATING;
324 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
325 if (child_sd->s_type & CONFIGFS_USET_CREATING)
326 configfs_dir_set_ready(child_sd);
327 }
328
329 /*
330 * Check that a directory does not belong to a directory hierarchy being
331 * attached and not validated yet.
332 * @sd configfs_dirent of the directory to check
333 *
334 * @return non-zero iff the directory was validated
335 *
336 * Note: takes configfs_dirent_lock, so the result may change from false to true
337 * in two consecutive calls, but never from true to false.
338 */
339 int configfs_dirent_is_ready(struct configfs_dirent *sd)
340 {
341 int ret;
342
343 spin_lock(&configfs_dirent_lock);
344 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
345 spin_unlock(&configfs_dirent_lock);
346
347 return ret;
348 }
349
350 int configfs_create_link(struct configfs_symlink *sl,
351 struct dentry *parent,
352 struct dentry *dentry)
353 {
354 int err = 0;
355 umode_t mode = S_IFLNK | S_IRWXUGO;
356
357 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
358 CONFIGFS_ITEM_LINK);
359 if (!err) {
360 err = configfs_create(dentry, mode, init_symlink);
361 if (err) {
362 struct configfs_dirent *sd = dentry->d_fsdata;
363 if (sd) {
364 spin_lock(&configfs_dirent_lock);
365 list_del_init(&sd->s_sibling);
366 spin_unlock(&configfs_dirent_lock);
367 configfs_put(sd);
368 }
369 }
370 }
371 return err;
372 }
373
374 static void remove_dir(struct dentry * d)
375 {
376 struct dentry * parent = dget(d->d_parent);
377 struct configfs_dirent * sd;
378
379 sd = d->d_fsdata;
380 spin_lock(&configfs_dirent_lock);
381 list_del_init(&sd->s_sibling);
382 spin_unlock(&configfs_dirent_lock);
383 configfs_put(sd);
384 if (d_really_is_positive(d))
385 simple_rmdir(d_inode(parent),d);
386
387 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
388
389 dput(parent);
390 }
391
392 /**
393 * configfs_remove_dir - remove an config_item's directory.
394 * @item: config_item we're removing.
395 *
396 * The only thing special about this is that we remove any files in
397 * the directory before we remove the directory, and we've inlined
398 * what used to be configfs_rmdir() below, instead of calling separately.
399 *
400 * Caller holds the mutex of the item's inode
401 */
402
403 static void configfs_remove_dir(struct config_item * item)
404 {
405 struct dentry * dentry = dget(item->ci_dentry);
406
407 if (!dentry)
408 return;
409
410 remove_dir(dentry);
411 /**
412 * Drop reference from dget() on entrance.
413 */
414 dput(dentry);
415 }
416
417
418 /* attaches attribute's configfs_dirent to the dentry corresponding to the
419 * attribute file
420 */
421 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
422 {
423 struct configfs_attribute * attr = sd->s_element;
424 int error;
425
426 spin_lock(&configfs_dirent_lock);
427 dentry->d_fsdata = configfs_get(sd);
428 sd->s_dentry = dentry;
429 spin_unlock(&configfs_dirent_lock);
430
431 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
432 (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) ?
433 configfs_init_bin_file :
434 configfs_init_file);
435 if (error)
436 configfs_put(sd);
437 return error;
438 }
439
440 static struct dentry * configfs_lookup(struct inode *dir,
441 struct dentry *dentry,
442 unsigned int flags)
443 {
444 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
445 struct configfs_dirent * sd;
446 int found = 0;
447 int err;
448
449 /*
450 * Fake invisibility if dir belongs to a group/default groups hierarchy
451 * being attached
452 *
453 * This forbids userspace to read/write attributes of items which may
454 * not complete their initialization, since the dentries of the
455 * attributes won't be instantiated.
456 */
457 err = -ENOENT;
458 if (!configfs_dirent_is_ready(parent_sd))
459 goto out;
460
461 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
462 if (sd->s_type & CONFIGFS_NOT_PINNED) {
463 const unsigned char * name = configfs_get_name(sd);
464
465 if (strcmp(name, dentry->d_name.name))
466 continue;
467
468 found = 1;
469 err = configfs_attach_attr(sd, dentry);
470 break;
471 }
472 }
473
474 if (!found) {
475 /*
476 * If it doesn't exist and it isn't a NOT_PINNED item,
477 * it must be negative.
478 */
479 if (dentry->d_name.len > NAME_MAX)
480 return ERR_PTR(-ENAMETOOLONG);
481 d_add(dentry, NULL);
482 return NULL;
483 }
484
485 out:
486 return ERR_PTR(err);
487 }
488
489 /*
490 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
491 * attributes and are removed by rmdir(). We recurse, setting
492 * CONFIGFS_USET_DROPPING on all children that are candidates for
493 * default detach.
494 * If there is an error, the caller will reset the flags via
495 * configfs_detach_rollback().
496 */
497 static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
498 {
499 struct configfs_dirent *parent_sd = dentry->d_fsdata;
500 struct configfs_dirent *sd;
501 int ret;
502
503 /* Mark that we're trying to drop the group */
504 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
505
506 ret = -EBUSY;
507 if (!list_empty(&parent_sd->s_links))
508 goto out;
509
510 ret = 0;
511 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
512 if (!sd->s_element ||
513 (sd->s_type & CONFIGFS_NOT_PINNED))
514 continue;
515 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
516 /* Abort if racing with mkdir() */
517 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
518 if (wait)
519 *wait= dget(sd->s_dentry);
520 return -EAGAIN;
521 }
522
523 /*
524 * Yup, recursive. If there's a problem, blame
525 * deep nesting of default_groups
526 */
527 ret = configfs_detach_prep(sd->s_dentry, wait);
528 if (!ret)
529 continue;
530 } else
531 ret = -ENOTEMPTY;
532
533 break;
534 }
535
536 out:
537 return ret;
538 }
539
540 /*
541 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
542 * set.
543 */
544 static void configfs_detach_rollback(struct dentry *dentry)
545 {
546 struct configfs_dirent *parent_sd = dentry->d_fsdata;
547 struct configfs_dirent *sd;
548
549 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
550
551 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
552 if (sd->s_type & CONFIGFS_USET_DEFAULT)
553 configfs_detach_rollback(sd->s_dentry);
554 }
555
556 static void detach_attrs(struct config_item * item)
557 {
558 struct dentry * dentry = dget(item->ci_dentry);
559 struct configfs_dirent * parent_sd;
560 struct configfs_dirent * sd, * tmp;
561
562 if (!dentry)
563 return;
564
565 pr_debug("configfs %s: dropping attrs for dir\n",
566 dentry->d_name.name);
567
568 parent_sd = dentry->d_fsdata;
569 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
570 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
571 continue;
572 spin_lock(&configfs_dirent_lock);
573 list_del_init(&sd->s_sibling);
574 spin_unlock(&configfs_dirent_lock);
575 configfs_drop_dentry(sd, dentry);
576 configfs_put(sd);
577 }
578
579 /**
580 * Drop reference from dget() on entrance.
581 */
582 dput(dentry);
583 }
584
585 static int populate_attrs(struct config_item *item)
586 {
587 const struct config_item_type *t = item->ci_type;
588 struct configfs_attribute *attr;
589 struct configfs_bin_attribute *bin_attr;
590 int error = 0;
591 int i;
592
593 if (!t)
594 return -EINVAL;
595 if (t->ct_attrs) {
596 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
597 if ((error = configfs_create_file(item, attr)))
598 break;
599 }
600 }
601 if (t->ct_bin_attrs) {
602 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
603 error = configfs_create_bin_file(item, bin_attr);
604 if (error)
605 break;
606 }
607 }
608
609 if (error)
610 detach_attrs(item);
611
612 return error;
613 }
614
615 static int configfs_attach_group(struct config_item *parent_item,
616 struct config_item *item,
617 struct dentry *dentry);
618 static void configfs_detach_group(struct config_item *item);
619
620 static void detach_groups(struct config_group *group)
621 {
622 struct dentry * dentry = dget(group->cg_item.ci_dentry);
623 struct dentry *child;
624 struct configfs_dirent *parent_sd;
625 struct configfs_dirent *sd, *tmp;
626
627 if (!dentry)
628 return;
629
630 parent_sd = dentry->d_fsdata;
631 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
632 if (!sd->s_element ||
633 !(sd->s_type & CONFIGFS_USET_DEFAULT))
634 continue;
635
636 child = sd->s_dentry;
637
638 inode_lock(d_inode(child));
639
640 configfs_detach_group(sd->s_element);
641 d_inode(child)->i_flags |= S_DEAD;
642 dont_mount(child);
643
644 inode_unlock(d_inode(child));
645
646 d_delete(child);
647 dput(child);
648 }
649
650 /**
651 * Drop reference from dget() on entrance.
652 */
653 dput(dentry);
654 }
655
656 /*
657 * This fakes mkdir(2) on a default_groups[] entry. It
658 * creates a dentry, attachs it, and then does fixup
659 * on the sd->s_type.
660 *
661 * We could, perhaps, tweak our parent's ->mkdir for a minute and
662 * try using vfs_mkdir. Just a thought.
663 */
664 static int create_default_group(struct config_group *parent_group,
665 struct config_group *group)
666 {
667 int ret;
668 struct configfs_dirent *sd;
669 /* We trust the caller holds a reference to parent */
670 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
671
672 if (!group->cg_item.ci_name)
673 group->cg_item.ci_name = group->cg_item.ci_namebuf;
674
675 ret = -ENOMEM;
676 child = d_alloc_name(parent, group->cg_item.ci_name);
677 if (child) {
678 d_add(child, NULL);
679
680 ret = configfs_attach_group(&parent_group->cg_item,
681 &group->cg_item, child);
682 if (!ret) {
683 sd = child->d_fsdata;
684 sd->s_type |= CONFIGFS_USET_DEFAULT;
685 } else {
686 BUG_ON(d_inode(child));
687 d_drop(child);
688 dput(child);
689 }
690 }
691
692 return ret;
693 }
694
695 static int populate_groups(struct config_group *group)
696 {
697 struct config_group *new_group;
698 int ret = 0;
699
700 list_for_each_entry(new_group, &group->default_groups, group_entry) {
701 ret = create_default_group(group, new_group);
702 if (ret) {
703 detach_groups(group);
704 break;
705 }
706 }
707
708 return ret;
709 }
710
711 void configfs_remove_default_groups(struct config_group *group)
712 {
713 struct config_group *g, *n;
714
715 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
716 list_del(&g->group_entry);
717 config_item_put(&g->cg_item);
718 }
719 }
720 EXPORT_SYMBOL(configfs_remove_default_groups);
721
722 /*
723 * All of link_obj/unlink_obj/link_group/unlink_group require that
724 * subsys->su_mutex is held.
725 */
726
727 static void unlink_obj(struct config_item *item)
728 {
729 struct config_group *group;
730
731 group = item->ci_group;
732 if (group) {
733 list_del_init(&item->ci_entry);
734
735 item->ci_group = NULL;
736 item->ci_parent = NULL;
737
738 /* Drop the reference for ci_entry */
739 config_item_put(item);
740
741 /* Drop the reference for ci_parent */
742 config_group_put(group);
743 }
744 }
745
746 static void link_obj(struct config_item *parent_item, struct config_item *item)
747 {
748 /*
749 * Parent seems redundant with group, but it makes certain
750 * traversals much nicer.
751 */
752 item->ci_parent = parent_item;
753
754 /*
755 * We hold a reference on the parent for the child's ci_parent
756 * link.
757 */
758 item->ci_group = config_group_get(to_config_group(parent_item));
759 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
760
761 /*
762 * We hold a reference on the child for ci_entry on the parent's
763 * cg_children
764 */
765 config_item_get(item);
766 }
767
768 static void unlink_group(struct config_group *group)
769 {
770 struct config_group *new_group;
771
772 list_for_each_entry(new_group, &group->default_groups, group_entry)
773 unlink_group(new_group);
774
775 group->cg_subsys = NULL;
776 unlink_obj(&group->cg_item);
777 }
778
779 static void link_group(struct config_group *parent_group, struct config_group *group)
780 {
781 struct config_group *new_group;
782 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
783
784 link_obj(&parent_group->cg_item, &group->cg_item);
785
786 if (parent_group->cg_subsys)
787 subsys = parent_group->cg_subsys;
788 else if (configfs_is_root(&parent_group->cg_item))
789 subsys = to_configfs_subsystem(group);
790 else
791 BUG();
792 group->cg_subsys = subsys;
793
794 list_for_each_entry(new_group, &group->default_groups, group_entry)
795 link_group(group, new_group);
796 }
797
798 /*
799 * The goal is that configfs_attach_item() (and
800 * configfs_attach_group()) can be called from either the VFS or this
801 * module. That is, they assume that the items have been created,
802 * the dentry allocated, and the dcache is all ready to go.
803 *
804 * If they fail, they must clean up after themselves as if they
805 * had never been called. The caller (VFS or local function) will
806 * handle cleaning up the dcache bits.
807 *
808 * configfs_detach_group() and configfs_detach_item() behave similarly on
809 * the way out. They assume that the proper semaphores are held, they
810 * clean up the configfs items, and they expect their callers will
811 * handle the dcache bits.
812 */
813 static int configfs_attach_item(struct config_item *parent_item,
814 struct config_item *item,
815 struct dentry *dentry)
816 {
817 int ret;
818
819 ret = configfs_create_dir(item, dentry);
820 if (!ret) {
821 ret = populate_attrs(item);
822 if (ret) {
823 /*
824 * We are going to remove an inode and its dentry but
825 * the VFS may already have hit and used them. Thus,
826 * we must lock them as rmdir() would.
827 */
828 inode_lock(d_inode(dentry));
829 configfs_remove_dir(item);
830 d_inode(dentry)->i_flags |= S_DEAD;
831 dont_mount(dentry);
832 inode_unlock(d_inode(dentry));
833 d_delete(dentry);
834 }
835 }
836
837 return ret;
838 }
839
840 /* Caller holds the mutex of the item's inode */
841 static void configfs_detach_item(struct config_item *item)
842 {
843 detach_attrs(item);
844 configfs_remove_dir(item);
845 }
846
847 static int configfs_attach_group(struct config_item *parent_item,
848 struct config_item *item,
849 struct dentry *dentry)
850 {
851 int ret;
852 struct configfs_dirent *sd;
853
854 ret = configfs_attach_item(parent_item, item, dentry);
855 if (!ret) {
856 sd = dentry->d_fsdata;
857 sd->s_type |= CONFIGFS_USET_DIR;
858
859 /*
860 * FYI, we're faking mkdir in populate_groups()
861 * We must lock the group's inode to avoid races with the VFS
862 * which can already hit the inode and try to add/remove entries
863 * under it.
864 *
865 * We must also lock the inode to remove it safely in case of
866 * error, as rmdir() would.
867 */
868 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
869 configfs_adjust_dir_dirent_depth_before_populate(sd);
870 ret = populate_groups(to_config_group(item));
871 if (ret) {
872 configfs_detach_item(item);
873 d_inode(dentry)->i_flags |= S_DEAD;
874 dont_mount(dentry);
875 }
876 configfs_adjust_dir_dirent_depth_after_populate(sd);
877 inode_unlock(d_inode(dentry));
878 if (ret)
879 d_delete(dentry);
880 }
881
882 return ret;
883 }
884
885 /* Caller holds the mutex of the group's inode */
886 static void configfs_detach_group(struct config_item *item)
887 {
888 detach_groups(to_config_group(item));
889 configfs_detach_item(item);
890 }
891
892 /*
893 * After the item has been detached from the filesystem view, we are
894 * ready to tear it out of the hierarchy. Notify the client before
895 * we do that so they can perform any cleanup that requires
896 * navigating the hierarchy. A client does not need to provide this
897 * callback. The subsystem semaphore MUST be held by the caller, and
898 * references must be valid for both items. It also assumes the
899 * caller has validated ci_type.
900 */
901 static void client_disconnect_notify(struct config_item *parent_item,
902 struct config_item *item)
903 {
904 const struct config_item_type *type;
905
906 type = parent_item->ci_type;
907 BUG_ON(!type);
908
909 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
910 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
911 item);
912 }
913
914 /*
915 * Drop the initial reference from make_item()/make_group()
916 * This function assumes that reference is held on item
917 * and that item holds a valid reference to the parent. Also, it
918 * assumes the caller has validated ci_type.
919 */
920 static void client_drop_item(struct config_item *parent_item,
921 struct config_item *item)
922 {
923 const struct config_item_type *type;
924
925 type = parent_item->ci_type;
926 BUG_ON(!type);
927
928 /*
929 * If ->drop_item() exists, it is responsible for the
930 * config_item_put().
931 */
932 if (type->ct_group_ops && type->ct_group_ops->drop_item)
933 type->ct_group_ops->drop_item(to_config_group(parent_item),
934 item);
935 else
936 config_item_put(item);
937 }
938
939 #ifdef DEBUG
940 static void configfs_dump_one(struct configfs_dirent *sd, int level)
941 {
942 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
943
944 #define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
945 type_print(CONFIGFS_ROOT);
946 type_print(CONFIGFS_DIR);
947 type_print(CONFIGFS_ITEM_ATTR);
948 type_print(CONFIGFS_ITEM_LINK);
949 type_print(CONFIGFS_USET_DIR);
950 type_print(CONFIGFS_USET_DEFAULT);
951 type_print(CONFIGFS_USET_DROPPING);
952 #undef type_print
953 }
954
955 static int configfs_dump(struct configfs_dirent *sd, int level)
956 {
957 struct configfs_dirent *child_sd;
958 int ret = 0;
959
960 configfs_dump_one(sd, level);
961
962 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
963 return 0;
964
965 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
966 ret = configfs_dump(child_sd, level + 2);
967 if (ret)
968 break;
969 }
970
971 return ret;
972 }
973 #endif
974
975
976 /*
977 * configfs_depend_item() and configfs_undepend_item()
978 *
979 * WARNING: Do not call these from a configfs callback!
980 *
981 * This describes these functions and their helpers.
982 *
983 * Allow another kernel system to depend on a config_item. If this
984 * happens, the item cannot go away until the dependent can live without
985 * it. The idea is to give client modules as simple an interface as
986 * possible. When a system asks them to depend on an item, they just
987 * call configfs_depend_item(). If the item is live and the client
988 * driver is in good shape, we'll happily do the work for them.
989 *
990 * Why is the locking complex? Because configfs uses the VFS to handle
991 * all locking, but this function is called outside the normal
992 * VFS->configfs path. So it must take VFS locks to prevent the
993 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
994 * why you can't call these functions underneath configfs callbacks.
995 *
996 * Note, btw, that this can be called at *any* time, even when a configfs
997 * subsystem isn't registered, or when configfs is loading or unloading.
998 * Just like configfs_register_subsystem(). So we take the same
999 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1000 * If we can find the target item in the
1001 * configfs tree, it must be part of the subsystem tree as well, so we
1002 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1003 * locking out mkdir() and rmdir(), who might be racing us.
1004 */
1005
1006 /*
1007 * configfs_depend_prep()
1008 *
1009 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1010 * attributes. This is similar but not the same to configfs_detach_prep().
1011 * Note that configfs_detach_prep() expects the parent to be locked when it
1012 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1013 * do that so we can unlock it if we find nothing.
1014 *
1015 * Here we do a depth-first search of the dentry hierarchy looking for
1016 * our object.
1017 * We deliberately ignore items tagged as dropping since they are virtually
1018 * dead, as well as items in the middle of attachment since they virtually
1019 * do not exist yet. This completes the locking out of racing mkdir() and
1020 * rmdir().
1021 * Note: subdirectories in the middle of attachment start with s_type =
1022 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1023 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1024 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1025 *
1026 * If the target is not found, -ENOENT is bubbled up.
1027 *
1028 * This adds a requirement that all config_items be unique!
1029 *
1030 * This is recursive. There isn't
1031 * much on the stack, though, so folks that need this function - be careful
1032 * about your stack! Patches will be accepted to make it iterative.
1033 */
1034 static int configfs_depend_prep(struct dentry *origin,
1035 struct config_item *target)
1036 {
1037 struct configfs_dirent *child_sd, *sd;
1038 int ret = 0;
1039
1040 BUG_ON(!origin || !origin->d_fsdata);
1041 sd = origin->d_fsdata;
1042
1043 if (sd->s_element == target) /* Boo-yah */
1044 goto out;
1045
1046 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1047 if ((child_sd->s_type & CONFIGFS_DIR) &&
1048 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1049 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1050 ret = configfs_depend_prep(child_sd->s_dentry,
1051 target);
1052 if (!ret)
1053 goto out; /* Child path boo-yah */
1054 }
1055 }
1056
1057 /* We looped all our children and didn't find target */
1058 ret = -ENOENT;
1059
1060 out:
1061 return ret;
1062 }
1063
1064 static int configfs_do_depend_item(struct dentry *subsys_dentry,
1065 struct config_item *target)
1066 {
1067 struct configfs_dirent *p;
1068 int ret;
1069
1070 spin_lock(&configfs_dirent_lock);
1071 /* Scan the tree, return 0 if found */
1072 ret = configfs_depend_prep(subsys_dentry, target);
1073 if (ret)
1074 goto out_unlock_dirent_lock;
1075
1076 /*
1077 * We are sure that the item is not about to be removed by rmdir(), and
1078 * not in the middle of attachment by mkdir().
1079 */
1080 p = target->ci_dentry->d_fsdata;
1081 p->s_dependent_count += 1;
1082
1083 out_unlock_dirent_lock:
1084 spin_unlock(&configfs_dirent_lock);
1085
1086 return ret;
1087 }
1088
1089 static inline struct configfs_dirent *
1090 configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1091 struct config_item *subsys_item)
1092 {
1093 struct configfs_dirent *p;
1094 struct configfs_dirent *ret = NULL;
1095
1096 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1097 if (p->s_type & CONFIGFS_DIR &&
1098 p->s_element == subsys_item) {
1099 ret = p;
1100 break;
1101 }
1102 }
1103
1104 return ret;
1105 }
1106
1107
1108 int configfs_depend_item(struct configfs_subsystem *subsys,
1109 struct config_item *target)
1110 {
1111 int ret;
1112 struct configfs_dirent *subsys_sd;
1113 struct config_item *s_item = &subsys->su_group.cg_item;
1114 struct dentry *root;
1115
1116 /*
1117 * Pin the configfs filesystem. This means we can safely access
1118 * the root of the configfs filesystem.
1119 */
1120 root = configfs_pin_fs();
1121 if (IS_ERR(root))
1122 return PTR_ERR(root);
1123
1124 /*
1125 * Next, lock the root directory. We're going to check that the
1126 * subsystem is really registered, and so we need to lock out
1127 * configfs_[un]register_subsystem().
1128 */
1129 inode_lock(d_inode(root));
1130
1131 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1132 if (!subsys_sd) {
1133 ret = -ENOENT;
1134 goto out_unlock_fs;
1135 }
1136
1137 /* Ok, now we can trust subsys/s_item */
1138 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1139
1140 out_unlock_fs:
1141 inode_unlock(d_inode(root));
1142
1143 /*
1144 * If we succeeded, the fs is pinned via other methods. If not,
1145 * we're done with it anyway. So release_fs() is always right.
1146 */
1147 configfs_release_fs();
1148
1149 return ret;
1150 }
1151 EXPORT_SYMBOL(configfs_depend_item);
1152
1153 /*
1154 * Release the dependent linkage. This is much simpler than
1155 * configfs_depend_item() because we know that that the client driver is
1156 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1157 */
1158 void configfs_undepend_item(struct config_item *target)
1159 {
1160 struct configfs_dirent *sd;
1161
1162 /*
1163 * Since we can trust everything is pinned, we just need
1164 * configfs_dirent_lock.
1165 */
1166 spin_lock(&configfs_dirent_lock);
1167
1168 sd = target->ci_dentry->d_fsdata;
1169 BUG_ON(sd->s_dependent_count < 1);
1170
1171 sd->s_dependent_count -= 1;
1172
1173 /*
1174 * After this unlock, we cannot trust the item to stay alive!
1175 * DO NOT REFERENCE item after this unlock.
1176 */
1177 spin_unlock(&configfs_dirent_lock);
1178 }
1179 EXPORT_SYMBOL(configfs_undepend_item);
1180
1181 /*
1182 * caller_subsys is a caller's subsystem not target's. This is used to
1183 * determine if we should lock root and check subsys or not. When we are
1184 * in the same subsystem as our target there is no need to do locking as
1185 * we know that subsys is valid and is not unregistered during this function
1186 * as we are called from callback of one of his children and VFS holds a lock
1187 * on some inode. Otherwise we have to lock our root to ensure that target's
1188 * subsystem it is not unregistered during this function.
1189 */
1190 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1191 struct config_item *target)
1192 {
1193 struct configfs_subsystem *target_subsys;
1194 struct config_group *root, *parent;
1195 struct configfs_dirent *subsys_sd;
1196 int ret = -ENOENT;
1197
1198 /* Disallow this function for configfs root */
1199 if (configfs_is_root(target))
1200 return -EINVAL;
1201
1202 parent = target->ci_group;
1203 /*
1204 * This may happen when someone is trying to depend root
1205 * directory of some subsystem
1206 */
1207 if (configfs_is_root(&parent->cg_item)) {
1208 target_subsys = to_configfs_subsystem(to_config_group(target));
1209 root = parent;
1210 } else {
1211 target_subsys = parent->cg_subsys;
1212 /* Find a cofnigfs root as we may need it for locking */
1213 for (root = parent; !configfs_is_root(&root->cg_item);
1214 root = root->cg_item.ci_group)
1215 ;
1216 }
1217
1218 if (target_subsys != caller_subsys) {
1219 /*
1220 * We are in other configfs subsystem, so we have to do
1221 * additional locking to prevent other subsystem from being
1222 * unregistered
1223 */
1224 inode_lock(d_inode(root->cg_item.ci_dentry));
1225
1226 /*
1227 * As we are trying to depend item from other subsystem
1228 * we have to check if this subsystem is still registered
1229 */
1230 subsys_sd = configfs_find_subsys_dentry(
1231 root->cg_item.ci_dentry->d_fsdata,
1232 &target_subsys->su_group.cg_item);
1233 if (!subsys_sd)
1234 goto out_root_unlock;
1235 } else {
1236 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1237 }
1238
1239 /* Now we can execute core of depend item */
1240 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1241
1242 if (target_subsys != caller_subsys)
1243 out_root_unlock:
1244 /*
1245 * We were called from subsystem other than our target so we
1246 * took some locks so now it's time to release them
1247 */
1248 inode_unlock(d_inode(root->cg_item.ci_dentry));
1249
1250 return ret;
1251 }
1252 EXPORT_SYMBOL(configfs_depend_item_unlocked);
1253
1254 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1255 {
1256 int ret = 0;
1257 int module_got = 0;
1258 struct config_group *group = NULL;
1259 struct config_item *item = NULL;
1260 struct config_item *parent_item;
1261 struct configfs_subsystem *subsys;
1262 struct configfs_dirent *sd;
1263 const struct config_item_type *type;
1264 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1265 char *name;
1266
1267 sd = dentry->d_parent->d_fsdata;
1268
1269 /*
1270 * Fake invisibility if dir belongs to a group/default groups hierarchy
1271 * being attached
1272 */
1273 if (!configfs_dirent_is_ready(sd)) {
1274 ret = -ENOENT;
1275 goto out;
1276 }
1277
1278 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1279 ret = -EPERM;
1280 goto out;
1281 }
1282
1283 /* Get a working ref for the duration of this function */
1284 parent_item = configfs_get_config_item(dentry->d_parent);
1285 type = parent_item->ci_type;
1286 subsys = to_config_group(parent_item)->cg_subsys;
1287 BUG_ON(!subsys);
1288
1289 if (!type || !type->ct_group_ops ||
1290 (!type->ct_group_ops->make_group &&
1291 !type->ct_group_ops->make_item)) {
1292 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1293 goto out_put;
1294 }
1295
1296 /*
1297 * The subsystem may belong to a different module than the item
1298 * being created. We don't want to safely pin the new item but
1299 * fail to pin the subsystem it sits under.
1300 */
1301 if (!subsys->su_group.cg_item.ci_type) {
1302 ret = -EINVAL;
1303 goto out_put;
1304 }
1305 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1306 if (!try_module_get(subsys_owner)) {
1307 ret = -EINVAL;
1308 goto out_put;
1309 }
1310
1311 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1312 if (!name) {
1313 ret = -ENOMEM;
1314 goto out_subsys_put;
1315 }
1316
1317 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1318
1319 mutex_lock(&subsys->su_mutex);
1320 if (type->ct_group_ops->make_group) {
1321 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1322 if (!group)
1323 group = ERR_PTR(-ENOMEM);
1324 if (!IS_ERR(group)) {
1325 link_group(to_config_group(parent_item), group);
1326 item = &group->cg_item;
1327 } else
1328 ret = PTR_ERR(group);
1329 } else {
1330 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1331 if (!item)
1332 item = ERR_PTR(-ENOMEM);
1333 if (!IS_ERR(item))
1334 link_obj(parent_item, item);
1335 else
1336 ret = PTR_ERR(item);
1337 }
1338 mutex_unlock(&subsys->su_mutex);
1339
1340 kfree(name);
1341 if (ret) {
1342 /*
1343 * If ret != 0, then link_obj() was never called.
1344 * There are no extra references to clean up.
1345 */
1346 goto out_subsys_put;
1347 }
1348
1349 /*
1350 * link_obj() has been called (via link_group() for groups).
1351 * From here on out, errors must clean that up.
1352 */
1353
1354 type = item->ci_type;
1355 if (!type) {
1356 ret = -EINVAL;
1357 goto out_unlink;
1358 }
1359
1360 new_item_owner = type->ct_owner;
1361 if (!try_module_get(new_item_owner)) {
1362 ret = -EINVAL;
1363 goto out_unlink;
1364 }
1365
1366 /*
1367 * I hate doing it this way, but if there is
1368 * an error, module_put() probably should
1369 * happen after any cleanup.
1370 */
1371 module_got = 1;
1372
1373 /*
1374 * Make racing rmdir() fail if it did not tag parent with
1375 * CONFIGFS_USET_DROPPING
1376 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1377 * fail and let rmdir() terminate correctly
1378 */
1379 spin_lock(&configfs_dirent_lock);
1380 /* This will make configfs_detach_prep() fail */
1381 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1382 spin_unlock(&configfs_dirent_lock);
1383
1384 if (group)
1385 ret = configfs_attach_group(parent_item, item, dentry);
1386 else
1387 ret = configfs_attach_item(parent_item, item, dentry);
1388
1389 spin_lock(&configfs_dirent_lock);
1390 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1391 if (!ret)
1392 configfs_dir_set_ready(dentry->d_fsdata);
1393 spin_unlock(&configfs_dirent_lock);
1394
1395 out_unlink:
1396 if (ret) {
1397 /* Tear down everything we built up */
1398 mutex_lock(&subsys->su_mutex);
1399
1400 client_disconnect_notify(parent_item, item);
1401 if (group)
1402 unlink_group(group);
1403 else
1404 unlink_obj(item);
1405 client_drop_item(parent_item, item);
1406
1407 mutex_unlock(&subsys->su_mutex);
1408
1409 if (module_got)
1410 module_put(new_item_owner);
1411 }
1412
1413 out_subsys_put:
1414 if (ret)
1415 module_put(subsys_owner);
1416
1417 out_put:
1418 /*
1419 * link_obj()/link_group() took a reference from child->parent,
1420 * so the parent is safely pinned. We can drop our working
1421 * reference.
1422 */
1423 config_item_put(parent_item);
1424
1425 out:
1426 return ret;
1427 }
1428
1429 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1430 {
1431 struct config_item *parent_item;
1432 struct config_item *item;
1433 struct configfs_subsystem *subsys;
1434 struct configfs_dirent *sd;
1435 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1436 int ret;
1437
1438 sd = dentry->d_fsdata;
1439 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1440 return -EPERM;
1441
1442 /* Get a working ref until we have the child */
1443 parent_item = configfs_get_config_item(dentry->d_parent);
1444 subsys = to_config_group(parent_item)->cg_subsys;
1445 BUG_ON(!subsys);
1446
1447 if (!parent_item->ci_type) {
1448 config_item_put(parent_item);
1449 return -EINVAL;
1450 }
1451
1452 /* configfs_mkdir() shouldn't have allowed this */
1453 BUG_ON(!subsys->su_group.cg_item.ci_type);
1454 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1455
1456 /*
1457 * Ensure that no racing symlink() will make detach_prep() fail while
1458 * the new link is temporarily attached
1459 */
1460 do {
1461 struct dentry *wait;
1462
1463 mutex_lock(&configfs_symlink_mutex);
1464 spin_lock(&configfs_dirent_lock);
1465 /*
1466 * Here's where we check for dependents. We're protected by
1467 * configfs_dirent_lock.
1468 * If no dependent, atomically tag the item as dropping.
1469 */
1470 ret = sd->s_dependent_count ? -EBUSY : 0;
1471 if (!ret) {
1472 ret = configfs_detach_prep(dentry, &wait);
1473 if (ret)
1474 configfs_detach_rollback(dentry);
1475 }
1476 spin_unlock(&configfs_dirent_lock);
1477 mutex_unlock(&configfs_symlink_mutex);
1478
1479 if (ret) {
1480 if (ret != -EAGAIN) {
1481 config_item_put(parent_item);
1482 return ret;
1483 }
1484
1485 /* Wait until the racing operation terminates */
1486 inode_lock(d_inode(wait));
1487 inode_unlock(d_inode(wait));
1488 dput(wait);
1489 }
1490 } while (ret == -EAGAIN);
1491
1492 /* Get a working ref for the duration of this function */
1493 item = configfs_get_config_item(dentry);
1494
1495 /* Drop reference from above, item already holds one. */
1496 config_item_put(parent_item);
1497
1498 if (item->ci_type)
1499 dead_item_owner = item->ci_type->ct_owner;
1500
1501 if (sd->s_type & CONFIGFS_USET_DIR) {
1502 configfs_detach_group(item);
1503
1504 mutex_lock(&subsys->su_mutex);
1505 client_disconnect_notify(parent_item, item);
1506 unlink_group(to_config_group(item));
1507 } else {
1508 configfs_detach_item(item);
1509
1510 mutex_lock(&subsys->su_mutex);
1511 client_disconnect_notify(parent_item, item);
1512 unlink_obj(item);
1513 }
1514
1515 client_drop_item(parent_item, item);
1516 mutex_unlock(&subsys->su_mutex);
1517
1518 /* Drop our reference from above */
1519 config_item_put(item);
1520
1521 module_put(dead_item_owner);
1522 module_put(subsys_owner);
1523
1524 return 0;
1525 }
1526
1527 const struct inode_operations configfs_dir_inode_operations = {
1528 .mkdir = configfs_mkdir,
1529 .rmdir = configfs_rmdir,
1530 .symlink = configfs_symlink,
1531 .unlink = configfs_unlink,
1532 .lookup = configfs_lookup,
1533 .setattr = configfs_setattr,
1534 };
1535
1536 const struct inode_operations configfs_root_inode_operations = {
1537 .lookup = configfs_lookup,
1538 .setattr = configfs_setattr,
1539 };
1540
1541 #if 0
1542 int configfs_rename_dir(struct config_item * item, const char *new_name)
1543 {
1544 int error = 0;
1545 struct dentry * new_dentry, * parent;
1546
1547 if (!strcmp(config_item_name(item), new_name))
1548 return -EINVAL;
1549
1550 if (!item->parent)
1551 return -EINVAL;
1552
1553 down_write(&configfs_rename_sem);
1554 parent = item->parent->dentry;
1555
1556 inode_lock(d_inode(parent));
1557
1558 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1559 if (!IS_ERR(new_dentry)) {
1560 if (d_really_is_negative(new_dentry)) {
1561 error = config_item_set_name(item, "%s", new_name);
1562 if (!error) {
1563 d_add(new_dentry, NULL);
1564 d_move(item->dentry, new_dentry);
1565 }
1566 else
1567 d_delete(new_dentry);
1568 } else
1569 error = -EEXIST;
1570 dput(new_dentry);
1571 }
1572 inode_unlock(d_inode(parent));
1573 up_write(&configfs_rename_sem);
1574
1575 return error;
1576 }
1577 #endif
1578
1579 static int configfs_dir_open(struct inode *inode, struct file *file)
1580 {
1581 struct dentry * dentry = file->f_path.dentry;
1582 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1583 int err;
1584
1585 inode_lock(d_inode(dentry));
1586 /*
1587 * Fake invisibility if dir belongs to a group/default groups hierarchy
1588 * being attached
1589 */
1590 err = -ENOENT;
1591 if (configfs_dirent_is_ready(parent_sd)) {
1592 file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1593 if (IS_ERR(file->private_data))
1594 err = PTR_ERR(file->private_data);
1595 else
1596 err = 0;
1597 }
1598 inode_unlock(d_inode(dentry));
1599
1600 return err;
1601 }
1602
1603 static int configfs_dir_close(struct inode *inode, struct file *file)
1604 {
1605 struct dentry * dentry = file->f_path.dentry;
1606 struct configfs_dirent * cursor = file->private_data;
1607
1608 inode_lock(d_inode(dentry));
1609 spin_lock(&configfs_dirent_lock);
1610 list_del_init(&cursor->s_sibling);
1611 spin_unlock(&configfs_dirent_lock);
1612 inode_unlock(d_inode(dentry));
1613
1614 release_configfs_dirent(cursor);
1615
1616 return 0;
1617 }
1618
1619 /* Relationship between s_mode and the DT_xxx types */
1620 static inline unsigned char dt_type(struct configfs_dirent *sd)
1621 {
1622 return (sd->s_mode >> 12) & 15;
1623 }
1624
1625 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1626 {
1627 struct dentry *dentry = file->f_path.dentry;
1628 struct super_block *sb = dentry->d_sb;
1629 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1630 struct configfs_dirent *cursor = file->private_data;
1631 struct list_head *p, *q = &cursor->s_sibling;
1632 ino_t ino = 0;
1633
1634 if (!dir_emit_dots(file, ctx))
1635 return 0;
1636 spin_lock(&configfs_dirent_lock);
1637 if (ctx->pos == 2)
1638 list_move(q, &parent_sd->s_children);
1639 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1640 struct configfs_dirent *next;
1641 const char *name;
1642 int len;
1643 struct inode *inode = NULL;
1644
1645 next = list_entry(p, struct configfs_dirent, s_sibling);
1646 if (!next->s_element)
1647 continue;
1648
1649 /*
1650 * We'll have a dentry and an inode for
1651 * PINNED items and for open attribute
1652 * files. We lock here to prevent a race
1653 * with configfs_d_iput() clearing
1654 * s_dentry before calling iput().
1655 *
1656 * Why do we go to the trouble? If
1657 * someone has an attribute file open,
1658 * the inode number should match until
1659 * they close it. Beyond that, we don't
1660 * care.
1661 */
1662 dentry = next->s_dentry;
1663 if (dentry)
1664 inode = d_inode(dentry);
1665 if (inode)
1666 ino = inode->i_ino;
1667 spin_unlock(&configfs_dirent_lock);
1668 if (!inode)
1669 ino = iunique(sb, 2);
1670
1671 name = configfs_get_name(next);
1672 len = strlen(name);
1673
1674 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1675 return 0;
1676
1677 spin_lock(&configfs_dirent_lock);
1678 list_move(q, p);
1679 p = q;
1680 ctx->pos++;
1681 }
1682 spin_unlock(&configfs_dirent_lock);
1683 return 0;
1684 }
1685
1686 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1687 {
1688 struct dentry * dentry = file->f_path.dentry;
1689
1690 switch (whence) {
1691 case 1:
1692 offset += file->f_pos;
1693 /* fall through */
1694 case 0:
1695 if (offset >= 0)
1696 break;
1697 /* fall through */
1698 default:
1699 return -EINVAL;
1700 }
1701 if (offset != file->f_pos) {
1702 file->f_pos = offset;
1703 if (file->f_pos >= 2) {
1704 struct configfs_dirent *sd = dentry->d_fsdata;
1705 struct configfs_dirent *cursor = file->private_data;
1706 struct list_head *p;
1707 loff_t n = file->f_pos - 2;
1708
1709 spin_lock(&configfs_dirent_lock);
1710 list_del(&cursor->s_sibling);
1711 p = sd->s_children.next;
1712 while (n && p != &sd->s_children) {
1713 struct configfs_dirent *next;
1714 next = list_entry(p, struct configfs_dirent,
1715 s_sibling);
1716 if (next->s_element)
1717 n--;
1718 p = p->next;
1719 }
1720 list_add_tail(&cursor->s_sibling, p);
1721 spin_unlock(&configfs_dirent_lock);
1722 }
1723 }
1724 return offset;
1725 }
1726
1727 const struct file_operations configfs_dir_operations = {
1728 .open = configfs_dir_open,
1729 .release = configfs_dir_close,
1730 .llseek = configfs_dir_lseek,
1731 .read = generic_read_dir,
1732 .iterate_shared = configfs_readdir,
1733 };
1734
1735 /**
1736 * configfs_register_group - creates a parent-child relation between two groups
1737 * @parent_group: parent group
1738 * @group: child group
1739 *
1740 * link groups, creates dentry for the child and attaches it to the
1741 * parent dentry.
1742 *
1743 * Return: 0 on success, negative errno code on error
1744 */
1745 int configfs_register_group(struct config_group *parent_group,
1746 struct config_group *group)
1747 {
1748 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1749 struct dentry *parent;
1750 int ret;
1751
1752 mutex_lock(&subsys->su_mutex);
1753 link_group(parent_group, group);
1754 mutex_unlock(&subsys->su_mutex);
1755
1756 parent = parent_group->cg_item.ci_dentry;
1757
1758 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1759 ret = create_default_group(parent_group, group);
1760 if (!ret) {
1761 spin_lock(&configfs_dirent_lock);
1762 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1763 spin_unlock(&configfs_dirent_lock);
1764 }
1765 inode_unlock(d_inode(parent));
1766 return ret;
1767 }
1768 EXPORT_SYMBOL(configfs_register_group);
1769
1770 /**
1771 * configfs_unregister_group() - unregisters a child group from its parent
1772 * @group: parent group to be unregistered
1773 *
1774 * Undoes configfs_register_group()
1775 */
1776 void configfs_unregister_group(struct config_group *group)
1777 {
1778 struct configfs_subsystem *subsys = group->cg_subsys;
1779 struct dentry *dentry = group->cg_item.ci_dentry;
1780 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1781
1782 mutex_lock(&subsys->su_mutex);
1783 if (!group->cg_item.ci_parent->ci_group) {
1784 /*
1785 * The parent has already been unlinked and detached
1786 * due to a rmdir.
1787 */
1788 goto unlink_group;
1789 }
1790 mutex_unlock(&subsys->su_mutex);
1791
1792 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1793 spin_lock(&configfs_dirent_lock);
1794 configfs_detach_prep(dentry, NULL);
1795 spin_unlock(&configfs_dirent_lock);
1796
1797 configfs_detach_group(&group->cg_item);
1798 d_inode(dentry)->i_flags |= S_DEAD;
1799 dont_mount(dentry);
1800 d_delete(dentry);
1801 inode_unlock(d_inode(parent));
1802
1803 dput(dentry);
1804
1805 mutex_lock(&subsys->su_mutex);
1806 unlink_group:
1807 unlink_group(group);
1808 mutex_unlock(&subsys->su_mutex);
1809 }
1810 EXPORT_SYMBOL(configfs_unregister_group);
1811
1812 /**
1813 * configfs_register_default_group() - allocates and registers a child group
1814 * @parent_group: parent group
1815 * @name: child group name
1816 * @item_type: child item type description
1817 *
1818 * boilerplate to allocate and register a child group with its parent. We need
1819 * kzalloc'ed memory because child's default_group is initially empty.
1820 *
1821 * Return: allocated config group or ERR_PTR() on error
1822 */
1823 struct config_group *
1824 configfs_register_default_group(struct config_group *parent_group,
1825 const char *name,
1826 const struct config_item_type *item_type)
1827 {
1828 int ret;
1829 struct config_group *group;
1830
1831 group = kzalloc(sizeof(*group), GFP_KERNEL);
1832 if (!group)
1833 return ERR_PTR(-ENOMEM);
1834 config_group_init_type_name(group, name, item_type);
1835
1836 ret = configfs_register_group(parent_group, group);
1837 if (ret) {
1838 kfree(group);
1839 return ERR_PTR(ret);
1840 }
1841 return group;
1842 }
1843 EXPORT_SYMBOL(configfs_register_default_group);
1844
1845 /**
1846 * configfs_unregister_default_group() - unregisters and frees a child group
1847 * @group: the group to act on
1848 */
1849 void configfs_unregister_default_group(struct config_group *group)
1850 {
1851 configfs_unregister_group(group);
1852 kfree(group);
1853 }
1854 EXPORT_SYMBOL(configfs_unregister_default_group);
1855
1856 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1857 {
1858 int err;
1859 struct config_group *group = &subsys->su_group;
1860 struct dentry *dentry;
1861 struct dentry *root;
1862 struct configfs_dirent *sd;
1863
1864 root = configfs_pin_fs();
1865 if (IS_ERR(root))
1866 return PTR_ERR(root);
1867
1868 if (!group->cg_item.ci_name)
1869 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1870
1871 sd = root->d_fsdata;
1872 link_group(to_config_group(sd->s_element), group);
1873
1874 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1875
1876 err = -ENOMEM;
1877 dentry = d_alloc_name(root, group->cg_item.ci_name);
1878 if (dentry) {
1879 d_add(dentry, NULL);
1880
1881 err = configfs_attach_group(sd->s_element, &group->cg_item,
1882 dentry);
1883 if (err) {
1884 BUG_ON(d_inode(dentry));
1885 d_drop(dentry);
1886 dput(dentry);
1887 } else {
1888 spin_lock(&configfs_dirent_lock);
1889 configfs_dir_set_ready(dentry->d_fsdata);
1890 spin_unlock(&configfs_dirent_lock);
1891 }
1892 }
1893
1894 inode_unlock(d_inode(root));
1895
1896 if (err) {
1897 unlink_group(group);
1898 configfs_release_fs();
1899 }
1900
1901 return err;
1902 }
1903
1904 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1905 {
1906 struct config_group *group = &subsys->su_group;
1907 struct dentry *dentry = group->cg_item.ci_dentry;
1908 struct dentry *root = dentry->d_sb->s_root;
1909
1910 if (dentry->d_parent != root) {
1911 pr_err("Tried to unregister non-subsystem!\n");
1912 return;
1913 }
1914
1915 inode_lock_nested(d_inode(root),
1916 I_MUTEX_PARENT);
1917 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1918 mutex_lock(&configfs_symlink_mutex);
1919 spin_lock(&configfs_dirent_lock);
1920 if (configfs_detach_prep(dentry, NULL)) {
1921 pr_err("Tried to unregister non-empty subsystem!\n");
1922 }
1923 spin_unlock(&configfs_dirent_lock);
1924 mutex_unlock(&configfs_symlink_mutex);
1925 configfs_detach_group(&group->cg_item);
1926 d_inode(dentry)->i_flags |= S_DEAD;
1927 dont_mount(dentry);
1928 inode_unlock(d_inode(dentry));
1929
1930 d_delete(dentry);
1931
1932 inode_unlock(d_inode(root));
1933
1934 dput(dentry);
1935
1936 unlink_group(group);
1937 configfs_release_fs();
1938 }
1939
1940 EXPORT_SYMBOL(configfs_register_subsystem);
1941 EXPORT_SYMBOL(configfs_unregister_subsystem);