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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
38DECLARE_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 */
51DEFINE_SPINLOCK(configfs_dirent_lock);
52
53static 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 BUG_ON(sd->s_dentry != dentry);
60 /* Coordinate with configfs_readdir */
61 spin_lock(&configfs_dirent_lock);
62 sd->s_dentry = NULL;
63 spin_unlock(&configfs_dirent_lock);
64 configfs_put(sd);
65 }
66 iput(inode);
67}
68
69/*
70 * We _must_ delete our dentries on last dput, as the chain-to-parent
71 * behavior is required to clear the parents of default_groups.
72 */
73static int configfs_d_delete(const struct dentry *dentry)
74{
75 return 1;
76}
77
78const struct dentry_operations configfs_dentry_ops = {
79 .d_iput = configfs_d_iput,
80 /* simple_delete_dentry() isn't exported */
81 .d_delete = configfs_d_delete,
82};
83
84#ifdef CONFIG_LOCKDEP
85
86/*
87 * Helpers to make lockdep happy with our recursive locking of default groups'
88 * inodes (see configfs_attach_group() and configfs_detach_group()).
89 * We put default groups i_mutexes in separate classes according to their depth
90 * from the youngest non-default group ancestor.
91 *
92 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
93 * groups A/B and A/C will have their inode's mutex in class
94 * default_group_class[0], and default group A/C/D will be in
95 * default_group_class[1].
96 *
97 * The lock classes are declared and assigned in inode.c, according to the
98 * s_depth value.
99 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
100 * default groups, and reset to -1 when all default groups are attached. During
101 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
102 * inode's mutex is set to default_group_class[s_depth - 1].
103 */
104
105static void configfs_init_dirent_depth(struct configfs_dirent *sd)
106{
107 sd->s_depth = -1;
108}
109
110static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
111 struct configfs_dirent *sd)
112{
113 int parent_depth = parent_sd->s_depth;
114
115 if (parent_depth >= 0)
116 sd->s_depth = parent_depth + 1;
117}
118
119static void
120configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
121{
122 /*
123 * item's i_mutex class is already setup, so s_depth is now only
124 * used to set new sub-directories s_depth, which is always done
125 * with item's i_mutex locked.
126 */
127 /*
128 * sd->s_depth == -1 iff we are a non default group.
129 * else (we are a default group) sd->s_depth > 0 (see
130 * create_dir()).
131 */
132 if (sd->s_depth == -1)
133 /*
134 * We are a non default group and we are going to create
135 * default groups.
136 */
137 sd->s_depth = 0;
138}
139
140static void
141configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
142{
143 /* We will not create default groups anymore. */
144 sd->s_depth = -1;
145}
146
147#else /* CONFIG_LOCKDEP */
148
149static void configfs_init_dirent_depth(struct configfs_dirent *sd)
150{
151}
152
153static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
154 struct configfs_dirent *sd)
155{
156}
157
158static void
159configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
160{
161}
162
163static void
164configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
165{
166}
167
168#endif /* CONFIG_LOCKDEP */
169
170/*
171 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
172 */
173static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
174 void *element, int type)
175{
176 struct configfs_dirent * sd;
177
178 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
179 if (!sd)
180 return ERR_PTR(-ENOMEM);
181
182 atomic_set(&sd->s_count, 1);
183 INIT_LIST_HEAD(&sd->s_links);
184 INIT_LIST_HEAD(&sd->s_children);
185 sd->s_element = element;
186 sd->s_type = type;
187 configfs_init_dirent_depth(sd);
188 spin_lock(&configfs_dirent_lock);
189 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
190 spin_unlock(&configfs_dirent_lock);
191 kmem_cache_free(configfs_dir_cachep, sd);
192 return ERR_PTR(-ENOENT);
193 }
194 list_add(&sd->s_sibling, &parent_sd->s_children);
195 spin_unlock(&configfs_dirent_lock);
196
197 return sd;
198}
199
200/*
201 *
202 * Return -EEXIST if there is already a configfs element with the same
203 * name for the same parent.
204 *
205 * called with parent inode's i_mutex held
206 */
207static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
208 const unsigned char *new)
209{
210 struct configfs_dirent * sd;
211
212 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
213 if (sd->s_element) {
214 const unsigned char *existing = configfs_get_name(sd);
215 if (strcmp(existing, new))
216 continue;
217 else
218 return -EEXIST;
219 }
220 }
221
222 return 0;
223}
224
225
226int configfs_make_dirent(struct configfs_dirent * parent_sd,
227 struct dentry * dentry, void * element,
228 umode_t mode, int type)
229{
230 struct configfs_dirent * sd;
231
232 sd = configfs_new_dirent(parent_sd, element, type);
233 if (IS_ERR(sd))
234 return PTR_ERR(sd);
235
236 sd->s_mode = mode;
237 sd->s_dentry = dentry;
238 if (dentry)
239 dentry->d_fsdata = configfs_get(sd);
240
241 return 0;
242}
243
244static int init_dir(struct inode * inode)
245{
246 inode->i_op = &configfs_dir_inode_operations;
247 inode->i_fop = &configfs_dir_operations;
248
249 /* directory inodes start off with i_nlink == 2 (for "." entry) */
250 inc_nlink(inode);
251 return 0;
252}
253
254static int configfs_init_file(struct inode * inode)
255{
256 inode->i_size = PAGE_SIZE;
257 inode->i_fop = &configfs_file_operations;
258 return 0;
259}
260
261static int init_symlink(struct inode * inode)
262{
263 inode->i_op = &configfs_symlink_inode_operations;
264 return 0;
265}
266
267static int create_dir(struct config_item * k, struct dentry * p,
268 struct dentry * d)
269{
270 int error;
271 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
272
273 error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
274 if (!error)
275 error = configfs_make_dirent(p->d_fsdata, d, k, mode,
276 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
277 if (!error) {
278 configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
279 error = configfs_create(d, mode, init_dir);
280 if (!error) {
281 inc_nlink(p->d_inode);
282 } else {
283 struct configfs_dirent *sd = d->d_fsdata;
284 if (sd) {
285 spin_lock(&configfs_dirent_lock);
286 list_del_init(&sd->s_sibling);
287 spin_unlock(&configfs_dirent_lock);
288 configfs_put(sd);
289 }
290 }
291 }
292 return error;
293}
294
295
296/**
297 * configfs_create_dir - create a directory for an config_item.
298 * @item: config_itemwe're creating directory for.
299 * @dentry: config_item's dentry.
300 *
301 * Note: user-created entries won't be allowed under this new directory
302 * until it is validated by configfs_dir_set_ready()
303 */
304
305static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
306{
307 struct dentry * parent;
308 int error = 0;
309
310 BUG_ON(!item);
311
312 if (item->ci_parent)
313 parent = item->ci_parent->ci_dentry;
314 else if (configfs_mount && configfs_mount->mnt_sb)
315 parent = configfs_mount->mnt_sb->s_root;
316 else
317 return -EFAULT;
318
319 error = create_dir(item,parent,dentry);
320 if (!error)
321 item->ci_dentry = dentry;
322 return error;
323}
324
325/*
326 * Allow userspace to create new entries under a new directory created with
327 * configfs_create_dir(), and under all of its chidlren directories recursively.
328 * @sd configfs_dirent of the new directory to validate
329 *
330 * Caller must hold configfs_dirent_lock.
331 */
332static void configfs_dir_set_ready(struct configfs_dirent *sd)
333{
334 struct configfs_dirent *child_sd;
335
336 sd->s_type &= ~CONFIGFS_USET_CREATING;
337 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
338 if (child_sd->s_type & CONFIGFS_USET_CREATING)
339 configfs_dir_set_ready(child_sd);
340}
341
342/*
343 * Check that a directory does not belong to a directory hierarchy being
344 * attached and not validated yet.
345 * @sd configfs_dirent of the directory to check
346 *
347 * @return non-zero iff the directory was validated
348 *
349 * Note: takes configfs_dirent_lock, so the result may change from false to true
350 * in two consecutive calls, but never from true to false.
351 */
352int configfs_dirent_is_ready(struct configfs_dirent *sd)
353{
354 int ret;
355
356 spin_lock(&configfs_dirent_lock);
357 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
358 spin_unlock(&configfs_dirent_lock);
359
360 return ret;
361}
362
363int configfs_create_link(struct configfs_symlink *sl,
364 struct dentry *parent,
365 struct dentry *dentry)
366{
367 int err = 0;
368 umode_t mode = S_IFLNK | S_IRWXUGO;
369
370 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
371 CONFIGFS_ITEM_LINK);
372 if (!err) {
373 err = configfs_create(dentry, mode, init_symlink);
374 if (err) {
375 struct configfs_dirent *sd = dentry->d_fsdata;
376 if (sd) {
377 spin_lock(&configfs_dirent_lock);
378 list_del_init(&sd->s_sibling);
379 spin_unlock(&configfs_dirent_lock);
380 configfs_put(sd);
381 }
382 }
383 }
384 return err;
385}
386
387static void remove_dir(struct dentry * d)
388{
389 struct dentry * parent = dget(d->d_parent);
390 struct configfs_dirent * sd;
391
392 sd = d->d_fsdata;
393 spin_lock(&configfs_dirent_lock);
394 list_del_init(&sd->s_sibling);
395 spin_unlock(&configfs_dirent_lock);
396 configfs_put(sd);
397 if (d->d_inode)
398 simple_rmdir(parent->d_inode,d);
399
400 pr_debug(" o %s removing done (%d)\n",d->d_name.name, d->d_count);
401
402 dput(parent);
403}
404
405/**
406 * configfs_remove_dir - remove an config_item's directory.
407 * @item: config_item we're removing.
408 *
409 * The only thing special about this is that we remove any files in
410 * the directory before we remove the directory, and we've inlined
411 * what used to be configfs_rmdir() below, instead of calling separately.
412 *
413 * Caller holds the mutex of the item's inode
414 */
415
416static void configfs_remove_dir(struct config_item * item)
417{
418 struct dentry * dentry = dget(item->ci_dentry);
419
420 if (!dentry)
421 return;
422
423 remove_dir(dentry);
424 /**
425 * Drop reference from dget() on entrance.
426 */
427 dput(dentry);
428}
429
430
431/* attaches attribute's configfs_dirent to the dentry corresponding to the
432 * attribute file
433 */
434static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
435{
436 struct configfs_attribute * attr = sd->s_element;
437 int error;
438
439 dentry->d_fsdata = configfs_get(sd);
440 sd->s_dentry = dentry;
441 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
442 configfs_init_file);
443 if (error) {
444 configfs_put(sd);
445 return error;
446 }
447
448 d_rehash(dentry);
449
450 return 0;
451}
452
453static struct dentry * configfs_lookup(struct inode *dir,
454 struct dentry *dentry,
455 struct nameidata *nd)
456{
457 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
458 struct configfs_dirent * sd;
459 int found = 0;
460 int err;
461
462 /*
463 * Fake invisibility if dir belongs to a group/default groups hierarchy
464 * being attached
465 *
466 * This forbids userspace to read/write attributes of items which may
467 * not complete their initialization, since the dentries of the
468 * attributes won't be instantiated.
469 */
470 err = -ENOENT;
471 if (!configfs_dirent_is_ready(parent_sd))
472 goto out;
473
474 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
475 if (sd->s_type & CONFIGFS_NOT_PINNED) {
476 const unsigned char * name = configfs_get_name(sd);
477
478 if (strcmp(name, dentry->d_name.name))
479 continue;
480
481 found = 1;
482 err = configfs_attach_attr(sd, dentry);
483 break;
484 }
485 }
486
487 if (!found) {
488 /*
489 * If it doesn't exist and it isn't a NOT_PINNED item,
490 * it must be negative.
491 */
492 if (dentry->d_name.len > NAME_MAX)
493 return ERR_PTR(-ENAMETOOLONG);
494 d_add(dentry, NULL);
495 return NULL;
496 }
497
498out:
499 return ERR_PTR(err);
500}
501
502/*
503 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
504 * attributes and are removed by rmdir(). We recurse, setting
505 * CONFIGFS_USET_DROPPING on all children that are candidates for
506 * default detach.
507 * If there is an error, the caller will reset the flags via
508 * configfs_detach_rollback().
509 */
510static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
511{
512 struct configfs_dirent *parent_sd = dentry->d_fsdata;
513 struct configfs_dirent *sd;
514 int ret;
515
516 /* Mark that we're trying to drop the group */
517 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
518
519 ret = -EBUSY;
520 if (!list_empty(&parent_sd->s_links))
521 goto out;
522
523 ret = 0;
524 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
525 if (!sd->s_element ||
526 (sd->s_type & CONFIGFS_NOT_PINNED))
527 continue;
528 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
529 /* Abort if racing with mkdir() */
530 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
531 if (wait_mutex)
532 *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
533 return -EAGAIN;
534 }
535
536 /*
537 * Yup, recursive. If there's a problem, blame
538 * deep nesting of default_groups
539 */
540 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
541 if (!ret)
542 continue;
543 } else
544 ret = -ENOTEMPTY;
545
546 break;
547 }
548
549out:
550 return ret;
551}
552
553/*
554 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
555 * set.
556 */
557static void configfs_detach_rollback(struct dentry *dentry)
558{
559 struct configfs_dirent *parent_sd = dentry->d_fsdata;
560 struct configfs_dirent *sd;
561
562 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
563
564 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
565 if (sd->s_type & CONFIGFS_USET_DEFAULT)
566 configfs_detach_rollback(sd->s_dentry);
567}
568
569static void detach_attrs(struct config_item * item)
570{
571 struct dentry * dentry = dget(item->ci_dentry);
572 struct configfs_dirent * parent_sd;
573 struct configfs_dirent * sd, * tmp;
574
575 if (!dentry)
576 return;
577
578 pr_debug("configfs %s: dropping attrs for dir\n",
579 dentry->d_name.name);
580
581 parent_sd = dentry->d_fsdata;
582 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
583 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
584 continue;
585 spin_lock(&configfs_dirent_lock);
586 list_del_init(&sd->s_sibling);
587 spin_unlock(&configfs_dirent_lock);
588 configfs_drop_dentry(sd, dentry);
589 configfs_put(sd);
590 }
591
592 /**
593 * Drop reference from dget() on entrance.
594 */
595 dput(dentry);
596}
597
598static int populate_attrs(struct config_item *item)
599{
600 struct config_item_type *t = item->ci_type;
601 struct configfs_attribute *attr;
602 int error = 0;
603 int i;
604
605 if (!t)
606 return -EINVAL;
607 if (t->ct_attrs) {
608 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
609 if ((error = configfs_create_file(item, attr)))
610 break;
611 }
612 }
613
614 if (error)
615 detach_attrs(item);
616
617 return error;
618}
619
620static int configfs_attach_group(struct config_item *parent_item,
621 struct config_item *item,
622 struct dentry *dentry);
623static void configfs_detach_group(struct config_item *item);
624
625static void detach_groups(struct config_group *group)
626{
627 struct dentry * dentry = dget(group->cg_item.ci_dentry);
628 struct dentry *child;
629 struct configfs_dirent *parent_sd;
630 struct configfs_dirent *sd, *tmp;
631
632 if (!dentry)
633 return;
634
635 parent_sd = dentry->d_fsdata;
636 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
637 if (!sd->s_element ||
638 !(sd->s_type & CONFIGFS_USET_DEFAULT))
639 continue;
640
641 child = sd->s_dentry;
642
643 mutex_lock(&child->d_inode->i_mutex);
644
645 configfs_detach_group(sd->s_element);
646 child->d_inode->i_flags |= S_DEAD;
647 dont_mount(child);
648
649 mutex_unlock(&child->d_inode->i_mutex);
650
651 d_delete(child);
652 dput(child);
653 }
654
655 /**
656 * Drop reference from dget() on entrance.
657 */
658 dput(dentry);
659}
660
661/*
662 * This fakes mkdir(2) on a default_groups[] entry. It
663 * creates a dentry, attachs it, and then does fixup
664 * on the sd->s_type.
665 *
666 * We could, perhaps, tweak our parent's ->mkdir for a minute and
667 * try using vfs_mkdir. Just a thought.
668 */
669static int create_default_group(struct config_group *parent_group,
670 struct config_group *group)
671{
672 int ret;
673 struct qstr name;
674 struct configfs_dirent *sd;
675 /* We trust the caller holds a reference to parent */
676 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
677
678 if (!group->cg_item.ci_name)
679 group->cg_item.ci_name = group->cg_item.ci_namebuf;
680 name.name = group->cg_item.ci_name;
681 name.len = strlen(name.name);
682 name.hash = full_name_hash(name.name, name.len);
683
684 ret = -ENOMEM;
685 child = d_alloc(parent, &name);
686 if (child) {
687 d_add(child, NULL);
688
689 ret = configfs_attach_group(&parent_group->cg_item,
690 &group->cg_item, child);
691 if (!ret) {
692 sd = child->d_fsdata;
693 sd->s_type |= CONFIGFS_USET_DEFAULT;
694 } else {
695 BUG_ON(child->d_inode);
696 d_drop(child);
697 dput(child);
698 }
699 }
700
701 return ret;
702}
703
704static int populate_groups(struct config_group *group)
705{
706 struct config_group *new_group;
707 int ret = 0;
708 int i;
709
710 if (group->default_groups) {
711 for (i = 0; group->default_groups[i]; i++) {
712 new_group = group->default_groups[i];
713
714 ret = create_default_group(group, new_group);
715 if (ret) {
716 detach_groups(group);
717 break;
718 }
719 }
720 }
721
722 return ret;
723}
724
725/*
726 * All of link_obj/unlink_obj/link_group/unlink_group require that
727 * subsys->su_mutex is held.
728 */
729
730static void unlink_obj(struct config_item *item)
731{
732 struct config_group *group;
733
734 group = item->ci_group;
735 if (group) {
736 list_del_init(&item->ci_entry);
737
738 item->ci_group = NULL;
739 item->ci_parent = NULL;
740
741 /* Drop the reference for ci_entry */
742 config_item_put(item);
743
744 /* Drop the reference for ci_parent */
745 config_group_put(group);
746 }
747}
748
749static void link_obj(struct config_item *parent_item, struct config_item *item)
750{
751 /*
752 * Parent seems redundant with group, but it makes certain
753 * traversals much nicer.
754 */
755 item->ci_parent = parent_item;
756
757 /*
758 * We hold a reference on the parent for the child's ci_parent
759 * link.
760 */
761 item->ci_group = config_group_get(to_config_group(parent_item));
762 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
763
764 /*
765 * We hold a reference on the child for ci_entry on the parent's
766 * cg_children
767 */
768 config_item_get(item);
769}
770
771static void unlink_group(struct config_group *group)
772{
773 int i;
774 struct config_group *new_group;
775
776 if (group->default_groups) {
777 for (i = 0; group->default_groups[i]; i++) {
778 new_group = group->default_groups[i];
779 unlink_group(new_group);
780 }
781 }
782
783 group->cg_subsys = NULL;
784 unlink_obj(&group->cg_item);
785}
786
787static void link_group(struct config_group *parent_group, struct config_group *group)
788{
789 int i;
790 struct config_group *new_group;
791 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
792
793 link_obj(&parent_group->cg_item, &group->cg_item);
794
795 if (parent_group->cg_subsys)
796 subsys = parent_group->cg_subsys;
797 else if (configfs_is_root(&parent_group->cg_item))
798 subsys = to_configfs_subsystem(group);
799 else
800 BUG();
801 group->cg_subsys = subsys;
802
803 if (group->default_groups) {
804 for (i = 0; group->default_groups[i]; i++) {
805 new_group = group->default_groups[i];
806 link_group(group, new_group);
807 }
808 }
809}
810
811/*
812 * The goal is that configfs_attach_item() (and
813 * configfs_attach_group()) can be called from either the VFS or this
814 * module. That is, they assume that the items have been created,
815 * the dentry allocated, and the dcache is all ready to go.
816 *
817 * If they fail, they must clean up after themselves as if they
818 * had never been called. The caller (VFS or local function) will
819 * handle cleaning up the dcache bits.
820 *
821 * configfs_detach_group() and configfs_detach_item() behave similarly on
822 * the way out. They assume that the proper semaphores are held, they
823 * clean up the configfs items, and they expect their callers will
824 * handle the dcache bits.
825 */
826static int configfs_attach_item(struct config_item *parent_item,
827 struct config_item *item,
828 struct dentry *dentry)
829{
830 int ret;
831
832 ret = configfs_create_dir(item, dentry);
833 if (!ret) {
834 ret = populate_attrs(item);
835 if (ret) {
836 /*
837 * We are going to remove an inode and its dentry but
838 * the VFS may already have hit and used them. Thus,
839 * we must lock them as rmdir() would.
840 */
841 mutex_lock(&dentry->d_inode->i_mutex);
842 configfs_remove_dir(item);
843 dentry->d_inode->i_flags |= S_DEAD;
844 dont_mount(dentry);
845 mutex_unlock(&dentry->d_inode->i_mutex);
846 d_delete(dentry);
847 }
848 }
849
850 return ret;
851}
852
853/* Caller holds the mutex of the item's inode */
854static void configfs_detach_item(struct config_item *item)
855{
856 detach_attrs(item);
857 configfs_remove_dir(item);
858}
859
860static int configfs_attach_group(struct config_item *parent_item,
861 struct config_item *item,
862 struct dentry *dentry)
863{
864 int ret;
865 struct configfs_dirent *sd;
866
867 ret = configfs_attach_item(parent_item, item, dentry);
868 if (!ret) {
869 sd = dentry->d_fsdata;
870 sd->s_type |= CONFIGFS_USET_DIR;
871
872 /*
873 * FYI, we're faking mkdir in populate_groups()
874 * We must lock the group's inode to avoid races with the VFS
875 * which can already hit the inode and try to add/remove entries
876 * under it.
877 *
878 * We must also lock the inode to remove it safely in case of
879 * error, as rmdir() would.
880 */
881 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
882 configfs_adjust_dir_dirent_depth_before_populate(sd);
883 ret = populate_groups(to_config_group(item));
884 if (ret) {
885 configfs_detach_item(item);
886 dentry->d_inode->i_flags |= S_DEAD;
887 dont_mount(dentry);
888 }
889 configfs_adjust_dir_dirent_depth_after_populate(sd);
890 mutex_unlock(&dentry->d_inode->i_mutex);
891 if (ret)
892 d_delete(dentry);
893 }
894
895 return ret;
896}
897
898/* Caller holds the mutex of the group's inode */
899static void configfs_detach_group(struct config_item *item)
900{
901 detach_groups(to_config_group(item));
902 configfs_detach_item(item);
903}
904
905/*
906 * After the item has been detached from the filesystem view, we are
907 * ready to tear it out of the hierarchy. Notify the client before
908 * we do that so they can perform any cleanup that requires
909 * navigating the hierarchy. A client does not need to provide this
910 * callback. The subsystem semaphore MUST be held by the caller, and
911 * references must be valid for both items. It also assumes the
912 * caller has validated ci_type.
913 */
914static void client_disconnect_notify(struct config_item *parent_item,
915 struct config_item *item)
916{
917 struct config_item_type *type;
918
919 type = parent_item->ci_type;
920 BUG_ON(!type);
921
922 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
923 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
924 item);
925}
926
927/*
928 * Drop the initial reference from make_item()/make_group()
929 * This function assumes that reference is held on item
930 * and that item holds a valid reference to the parent. Also, it
931 * assumes the caller has validated ci_type.
932 */
933static void client_drop_item(struct config_item *parent_item,
934 struct config_item *item)
935{
936 struct config_item_type *type;
937
938 type = parent_item->ci_type;
939 BUG_ON(!type);
940
941 /*
942 * If ->drop_item() exists, it is responsible for the
943 * config_item_put().
944 */
945 if (type->ct_group_ops && type->ct_group_ops->drop_item)
946 type->ct_group_ops->drop_item(to_config_group(parent_item),
947 item);
948 else
949 config_item_put(item);
950}
951
952#ifdef DEBUG
953static void configfs_dump_one(struct configfs_dirent *sd, int level)
954{
955 printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
956
957#define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
958 type_print(CONFIGFS_ROOT);
959 type_print(CONFIGFS_DIR);
960 type_print(CONFIGFS_ITEM_ATTR);
961 type_print(CONFIGFS_ITEM_LINK);
962 type_print(CONFIGFS_USET_DIR);
963 type_print(CONFIGFS_USET_DEFAULT);
964 type_print(CONFIGFS_USET_DROPPING);
965#undef type_print
966}
967
968static int configfs_dump(struct configfs_dirent *sd, int level)
969{
970 struct configfs_dirent *child_sd;
971 int ret = 0;
972
973 configfs_dump_one(sd, level);
974
975 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
976 return 0;
977
978 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
979 ret = configfs_dump(child_sd, level + 2);
980 if (ret)
981 break;
982 }
983
984 return ret;
985}
986#endif
987
988
989/*
990 * configfs_depend_item() and configfs_undepend_item()
991 *
992 * WARNING: Do not call these from a configfs callback!
993 *
994 * This describes these functions and their helpers.
995 *
996 * Allow another kernel system to depend on a config_item. If this
997 * happens, the item cannot go away until the dependent can live without
998 * it. The idea is to give client modules as simple an interface as
999 * possible. When a system asks them to depend on an item, they just
1000 * call configfs_depend_item(). If the item is live and the client
1001 * driver is in good shape, we'll happily do the work for them.
1002 *
1003 * Why is the locking complex? Because configfs uses the VFS to handle
1004 * all locking, but this function is called outside the normal
1005 * VFS->configfs path. So it must take VFS locks to prevent the
1006 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1007 * why you can't call these functions underneath configfs callbacks.
1008 *
1009 * Note, btw, that this can be called at *any* time, even when a configfs
1010 * subsystem isn't registered, or when configfs is loading or unloading.
1011 * Just like configfs_register_subsystem(). So we take the same
1012 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1013 * If we can find the target item in the
1014 * configfs tree, it must be part of the subsystem tree as well, so we
1015 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1016 * locking out mkdir() and rmdir(), who might be racing us.
1017 */
1018
1019/*
1020 * configfs_depend_prep()
1021 *
1022 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1023 * attributes. This is similar but not the same to configfs_detach_prep().
1024 * Note that configfs_detach_prep() expects the parent to be locked when it
1025 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1026 * do that so we can unlock it if we find nothing.
1027 *
1028 * Here we do a depth-first search of the dentry hierarchy looking for
1029 * our object.
1030 * We deliberately ignore items tagged as dropping since they are virtually
1031 * dead, as well as items in the middle of attachment since they virtually
1032 * do not exist yet. This completes the locking out of racing mkdir() and
1033 * rmdir().
1034 * Note: subdirectories in the middle of attachment start with s_type =
1035 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1036 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1037 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1038 *
1039 * If the target is not found, -ENOENT is bubbled up.
1040 *
1041 * This adds a requirement that all config_items be unique!
1042 *
1043 * This is recursive. There isn't
1044 * much on the stack, though, so folks that need this function - be careful
1045 * about your stack! Patches will be accepted to make it iterative.
1046 */
1047static int configfs_depend_prep(struct dentry *origin,
1048 struct config_item *target)
1049{
1050 struct configfs_dirent *child_sd, *sd = origin->d_fsdata;
1051 int ret = 0;
1052
1053 BUG_ON(!origin || !sd);
1054
1055 if (sd->s_element == target) /* Boo-yah */
1056 goto out;
1057
1058 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1059 if ((child_sd->s_type & CONFIGFS_DIR) &&
1060 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1061 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1062 ret = configfs_depend_prep(child_sd->s_dentry,
1063 target);
1064 if (!ret)
1065 goto out; /* Child path boo-yah */
1066 }
1067 }
1068
1069 /* We looped all our children and didn't find target */
1070 ret = -ENOENT;
1071
1072out:
1073 return ret;
1074}
1075
1076int configfs_depend_item(struct configfs_subsystem *subsys,
1077 struct config_item *target)
1078{
1079 int ret;
1080 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1081 struct config_item *s_item = &subsys->su_group.cg_item;
1082
1083 /*
1084 * Pin the configfs filesystem. This means we can safely access
1085 * the root of the configfs filesystem.
1086 */
1087 ret = configfs_pin_fs();
1088 if (ret)
1089 return ret;
1090
1091 /*
1092 * Next, lock the root directory. We're going to check that the
1093 * subsystem is really registered, and so we need to lock out
1094 * configfs_[un]register_subsystem().
1095 */
1096 mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1097
1098 root_sd = configfs_sb->s_root->d_fsdata;
1099
1100 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1101 if (p->s_type & CONFIGFS_DIR) {
1102 if (p->s_element == s_item) {
1103 subsys_sd = p;
1104 break;
1105 }
1106 }
1107 }
1108
1109 if (!subsys_sd) {
1110 ret = -ENOENT;
1111 goto out_unlock_fs;
1112 }
1113
1114 /* Ok, now we can trust subsys/s_item */
1115
1116 spin_lock(&configfs_dirent_lock);
1117 /* Scan the tree, return 0 if found */
1118 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1119 if (ret)
1120 goto out_unlock_dirent_lock;
1121
1122 /*
1123 * We are sure that the item is not about to be removed by rmdir(), and
1124 * not in the middle of attachment by mkdir().
1125 */
1126 p = target->ci_dentry->d_fsdata;
1127 p->s_dependent_count += 1;
1128
1129out_unlock_dirent_lock:
1130 spin_unlock(&configfs_dirent_lock);
1131out_unlock_fs:
1132 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1133
1134 /*
1135 * If we succeeded, the fs is pinned via other methods. If not,
1136 * we're done with it anyway. So release_fs() is always right.
1137 */
1138 configfs_release_fs();
1139
1140 return ret;
1141}
1142EXPORT_SYMBOL(configfs_depend_item);
1143
1144/*
1145 * Release the dependent linkage. This is much simpler than
1146 * configfs_depend_item() because we know that that the client driver is
1147 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1148 */
1149void configfs_undepend_item(struct configfs_subsystem *subsys,
1150 struct config_item *target)
1151{
1152 struct configfs_dirent *sd;
1153
1154 /*
1155 * Since we can trust everything is pinned, we just need
1156 * configfs_dirent_lock.
1157 */
1158 spin_lock(&configfs_dirent_lock);
1159
1160 sd = target->ci_dentry->d_fsdata;
1161 BUG_ON(sd->s_dependent_count < 1);
1162
1163 sd->s_dependent_count -= 1;
1164
1165 /*
1166 * After this unlock, we cannot trust the item to stay alive!
1167 * DO NOT REFERENCE item after this unlock.
1168 */
1169 spin_unlock(&configfs_dirent_lock);
1170}
1171EXPORT_SYMBOL(configfs_undepend_item);
1172
1173static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1174{
1175 int ret = 0;
1176 int module_got = 0;
1177 struct config_group *group = NULL;
1178 struct config_item *item = NULL;
1179 struct config_item *parent_item;
1180 struct configfs_subsystem *subsys;
1181 struct configfs_dirent *sd;
1182 struct config_item_type *type;
1183 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1184 char *name;
1185
1186 if (dentry->d_parent == configfs_sb->s_root) {
1187 ret = -EPERM;
1188 goto out;
1189 }
1190
1191 sd = dentry->d_parent->d_fsdata;
1192
1193 /*
1194 * Fake invisibility if dir belongs to a group/default groups hierarchy
1195 * being attached
1196 */
1197 if (!configfs_dirent_is_ready(sd)) {
1198 ret = -ENOENT;
1199 goto out;
1200 }
1201
1202 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1203 ret = -EPERM;
1204 goto out;
1205 }
1206
1207 /* Get a working ref for the duration of this function */
1208 parent_item = configfs_get_config_item(dentry->d_parent);
1209 type = parent_item->ci_type;
1210 subsys = to_config_group(parent_item)->cg_subsys;
1211 BUG_ON(!subsys);
1212
1213 if (!type || !type->ct_group_ops ||
1214 (!type->ct_group_ops->make_group &&
1215 !type->ct_group_ops->make_item)) {
1216 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1217 goto out_put;
1218 }
1219
1220 /*
1221 * The subsystem may belong to a different module than the item
1222 * being created. We don't want to safely pin the new item but
1223 * fail to pin the subsystem it sits under.
1224 */
1225 if (!subsys->su_group.cg_item.ci_type) {
1226 ret = -EINVAL;
1227 goto out_put;
1228 }
1229 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1230 if (!try_module_get(subsys_owner)) {
1231 ret = -EINVAL;
1232 goto out_put;
1233 }
1234
1235 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1236 if (!name) {
1237 ret = -ENOMEM;
1238 goto out_subsys_put;
1239 }
1240
1241 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1242
1243 mutex_lock(&subsys->su_mutex);
1244 if (type->ct_group_ops->make_group) {
1245 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1246 if (!group)
1247 group = ERR_PTR(-ENOMEM);
1248 if (!IS_ERR(group)) {
1249 link_group(to_config_group(parent_item), group);
1250 item = &group->cg_item;
1251 } else
1252 ret = PTR_ERR(group);
1253 } else {
1254 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1255 if (!item)
1256 item = ERR_PTR(-ENOMEM);
1257 if (!IS_ERR(item))
1258 link_obj(parent_item, item);
1259 else
1260 ret = PTR_ERR(item);
1261 }
1262 mutex_unlock(&subsys->su_mutex);
1263
1264 kfree(name);
1265 if (ret) {
1266 /*
1267 * If ret != 0, then link_obj() was never called.
1268 * There are no extra references to clean up.
1269 */
1270 goto out_subsys_put;
1271 }
1272
1273 /*
1274 * link_obj() has been called (via link_group() for groups).
1275 * From here on out, errors must clean that up.
1276 */
1277
1278 type = item->ci_type;
1279 if (!type) {
1280 ret = -EINVAL;
1281 goto out_unlink;
1282 }
1283
1284 new_item_owner = type->ct_owner;
1285 if (!try_module_get(new_item_owner)) {
1286 ret = -EINVAL;
1287 goto out_unlink;
1288 }
1289
1290 /*
1291 * I hate doing it this way, but if there is
1292 * an error, module_put() probably should
1293 * happen after any cleanup.
1294 */
1295 module_got = 1;
1296
1297 /*
1298 * Make racing rmdir() fail if it did not tag parent with
1299 * CONFIGFS_USET_DROPPING
1300 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1301 * fail and let rmdir() terminate correctly
1302 */
1303 spin_lock(&configfs_dirent_lock);
1304 /* This will make configfs_detach_prep() fail */
1305 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1306 spin_unlock(&configfs_dirent_lock);
1307
1308 if (group)
1309 ret = configfs_attach_group(parent_item, item, dentry);
1310 else
1311 ret = configfs_attach_item(parent_item, item, dentry);
1312
1313 spin_lock(&configfs_dirent_lock);
1314 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1315 if (!ret)
1316 configfs_dir_set_ready(dentry->d_fsdata);
1317 spin_unlock(&configfs_dirent_lock);
1318
1319out_unlink:
1320 if (ret) {
1321 /* Tear down everything we built up */
1322 mutex_lock(&subsys->su_mutex);
1323
1324 client_disconnect_notify(parent_item, item);
1325 if (group)
1326 unlink_group(group);
1327 else
1328 unlink_obj(item);
1329 client_drop_item(parent_item, item);
1330
1331 mutex_unlock(&subsys->su_mutex);
1332
1333 if (module_got)
1334 module_put(new_item_owner);
1335 }
1336
1337out_subsys_put:
1338 if (ret)
1339 module_put(subsys_owner);
1340
1341out_put:
1342 /*
1343 * link_obj()/link_group() took a reference from child->parent,
1344 * so the parent is safely pinned. We can drop our working
1345 * reference.
1346 */
1347 config_item_put(parent_item);
1348
1349out:
1350 return ret;
1351}
1352
1353static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1354{
1355 struct config_item *parent_item;
1356 struct config_item *item;
1357 struct configfs_subsystem *subsys;
1358 struct configfs_dirent *sd;
1359 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1360 int ret;
1361
1362 if (dentry->d_parent == configfs_sb->s_root)
1363 return -EPERM;
1364
1365 sd = dentry->d_fsdata;
1366 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1367 return -EPERM;
1368
1369 /* Get a working ref until we have the child */
1370 parent_item = configfs_get_config_item(dentry->d_parent);
1371 subsys = to_config_group(parent_item)->cg_subsys;
1372 BUG_ON(!subsys);
1373
1374 if (!parent_item->ci_type) {
1375 config_item_put(parent_item);
1376 return -EINVAL;
1377 }
1378
1379 /* configfs_mkdir() shouldn't have allowed this */
1380 BUG_ON(!subsys->su_group.cg_item.ci_type);
1381 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1382
1383 /*
1384 * Ensure that no racing symlink() will make detach_prep() fail while
1385 * the new link is temporarily attached
1386 */
1387 do {
1388 struct mutex *wait_mutex;
1389
1390 mutex_lock(&configfs_symlink_mutex);
1391 spin_lock(&configfs_dirent_lock);
1392 /*
1393 * Here's where we check for dependents. We're protected by
1394 * configfs_dirent_lock.
1395 * If no dependent, atomically tag the item as dropping.
1396 */
1397 ret = sd->s_dependent_count ? -EBUSY : 0;
1398 if (!ret) {
1399 ret = configfs_detach_prep(dentry, &wait_mutex);
1400 if (ret)
1401 configfs_detach_rollback(dentry);
1402 }
1403 spin_unlock(&configfs_dirent_lock);
1404 mutex_unlock(&configfs_symlink_mutex);
1405
1406 if (ret) {
1407 if (ret != -EAGAIN) {
1408 config_item_put(parent_item);
1409 return ret;
1410 }
1411
1412 /* Wait until the racing operation terminates */
1413 mutex_lock(wait_mutex);
1414 mutex_unlock(wait_mutex);
1415 }
1416 } while (ret == -EAGAIN);
1417
1418 /* Get a working ref for the duration of this function */
1419 item = configfs_get_config_item(dentry);
1420
1421 /* Drop reference from above, item already holds one. */
1422 config_item_put(parent_item);
1423
1424 if (item->ci_type)
1425 dead_item_owner = item->ci_type->ct_owner;
1426
1427 if (sd->s_type & CONFIGFS_USET_DIR) {
1428 configfs_detach_group(item);
1429
1430 mutex_lock(&subsys->su_mutex);
1431 client_disconnect_notify(parent_item, item);
1432 unlink_group(to_config_group(item));
1433 } else {
1434 configfs_detach_item(item);
1435
1436 mutex_lock(&subsys->su_mutex);
1437 client_disconnect_notify(parent_item, item);
1438 unlink_obj(item);
1439 }
1440
1441 client_drop_item(parent_item, item);
1442 mutex_unlock(&subsys->su_mutex);
1443
1444 /* Drop our reference from above */
1445 config_item_put(item);
1446
1447 module_put(dead_item_owner);
1448 module_put(subsys_owner);
1449
1450 return 0;
1451}
1452
1453const struct inode_operations configfs_dir_inode_operations = {
1454 .mkdir = configfs_mkdir,
1455 .rmdir = configfs_rmdir,
1456 .symlink = configfs_symlink,
1457 .unlink = configfs_unlink,
1458 .lookup = configfs_lookup,
1459 .setattr = configfs_setattr,
1460};
1461
1462#if 0
1463int configfs_rename_dir(struct config_item * item, const char *new_name)
1464{
1465 int error = 0;
1466 struct dentry * new_dentry, * parent;
1467
1468 if (!strcmp(config_item_name(item), new_name))
1469 return -EINVAL;
1470
1471 if (!item->parent)
1472 return -EINVAL;
1473
1474 down_write(&configfs_rename_sem);
1475 parent = item->parent->dentry;
1476
1477 mutex_lock(&parent->d_inode->i_mutex);
1478
1479 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1480 if (!IS_ERR(new_dentry)) {
1481 if (!new_dentry->d_inode) {
1482 error = config_item_set_name(item, "%s", new_name);
1483 if (!error) {
1484 d_add(new_dentry, NULL);
1485 d_move(item->dentry, new_dentry);
1486 }
1487 else
1488 d_delete(new_dentry);
1489 } else
1490 error = -EEXIST;
1491 dput(new_dentry);
1492 }
1493 mutex_unlock(&parent->d_inode->i_mutex);
1494 up_write(&configfs_rename_sem);
1495
1496 return error;
1497}
1498#endif
1499
1500static int configfs_dir_open(struct inode *inode, struct file *file)
1501{
1502 struct dentry * dentry = file->f_path.dentry;
1503 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1504 int err;
1505
1506 mutex_lock(&dentry->d_inode->i_mutex);
1507 /*
1508 * Fake invisibility if dir belongs to a group/default groups hierarchy
1509 * being attached
1510 */
1511 err = -ENOENT;
1512 if (configfs_dirent_is_ready(parent_sd)) {
1513 file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1514 if (IS_ERR(file->private_data))
1515 err = PTR_ERR(file->private_data);
1516 else
1517 err = 0;
1518 }
1519 mutex_unlock(&dentry->d_inode->i_mutex);
1520
1521 return err;
1522}
1523
1524static int configfs_dir_close(struct inode *inode, struct file *file)
1525{
1526 struct dentry * dentry = file->f_path.dentry;
1527 struct configfs_dirent * cursor = file->private_data;
1528
1529 mutex_lock(&dentry->d_inode->i_mutex);
1530 spin_lock(&configfs_dirent_lock);
1531 list_del_init(&cursor->s_sibling);
1532 spin_unlock(&configfs_dirent_lock);
1533 mutex_unlock(&dentry->d_inode->i_mutex);
1534
1535 release_configfs_dirent(cursor);
1536
1537 return 0;
1538}
1539
1540/* Relationship between s_mode and the DT_xxx types */
1541static inline unsigned char dt_type(struct configfs_dirent *sd)
1542{
1543 return (sd->s_mode >> 12) & 15;
1544}
1545
1546static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1547{
1548 struct dentry *dentry = filp->f_path.dentry;
1549 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1550 struct configfs_dirent *cursor = filp->private_data;
1551 struct list_head *p, *q = &cursor->s_sibling;
1552 ino_t ino = 0;
1553 int i = filp->f_pos;
1554
1555 switch (i) {
1556 case 0:
1557 ino = dentry->d_inode->i_ino;
1558 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1559 break;
1560 filp->f_pos++;
1561 i++;
1562 /* fallthrough */
1563 case 1:
1564 ino = parent_ino(dentry);
1565 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1566 break;
1567 filp->f_pos++;
1568 i++;
1569 /* fallthrough */
1570 default:
1571 if (filp->f_pos == 2) {
1572 spin_lock(&configfs_dirent_lock);
1573 list_move(q, &parent_sd->s_children);
1574 spin_unlock(&configfs_dirent_lock);
1575 }
1576 for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
1577 struct configfs_dirent *next;
1578 const char * name;
1579 int len;
1580 struct inode *inode = NULL;
1581
1582 next = list_entry(p, struct configfs_dirent,
1583 s_sibling);
1584 if (!next->s_element)
1585 continue;
1586
1587 name = configfs_get_name(next);
1588 len = strlen(name);
1589
1590 /*
1591 * We'll have a dentry and an inode for
1592 * PINNED items and for open attribute
1593 * files. We lock here to prevent a race
1594 * with configfs_d_iput() clearing
1595 * s_dentry before calling iput().
1596 *
1597 * Why do we go to the trouble? If
1598 * someone has an attribute file open,
1599 * the inode number should match until
1600 * they close it. Beyond that, we don't
1601 * care.
1602 */
1603 spin_lock(&configfs_dirent_lock);
1604 dentry = next->s_dentry;
1605 if (dentry)
1606 inode = dentry->d_inode;
1607 if (inode)
1608 ino = inode->i_ino;
1609 spin_unlock(&configfs_dirent_lock);
1610 if (!inode)
1611 ino = iunique(configfs_sb, 2);
1612
1613 if (filldir(dirent, name, len, filp->f_pos, ino,
1614 dt_type(next)) < 0)
1615 return 0;
1616
1617 spin_lock(&configfs_dirent_lock);
1618 list_move(q, p);
1619 spin_unlock(&configfs_dirent_lock);
1620 p = q;
1621 filp->f_pos++;
1622 }
1623 }
1624 return 0;
1625}
1626
1627static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
1628{
1629 struct dentry * dentry = file->f_path.dentry;
1630
1631 mutex_lock(&dentry->d_inode->i_mutex);
1632 switch (origin) {
1633 case 1:
1634 offset += file->f_pos;
1635 case 0:
1636 if (offset >= 0)
1637 break;
1638 default:
1639 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1640 return -EINVAL;
1641 }
1642 if (offset != file->f_pos) {
1643 file->f_pos = offset;
1644 if (file->f_pos >= 2) {
1645 struct configfs_dirent *sd = dentry->d_fsdata;
1646 struct configfs_dirent *cursor = file->private_data;
1647 struct list_head *p;
1648 loff_t n = file->f_pos - 2;
1649
1650 spin_lock(&configfs_dirent_lock);
1651 list_del(&cursor->s_sibling);
1652 p = sd->s_children.next;
1653 while (n && p != &sd->s_children) {
1654 struct configfs_dirent *next;
1655 next = list_entry(p, struct configfs_dirent,
1656 s_sibling);
1657 if (next->s_element)
1658 n--;
1659 p = p->next;
1660 }
1661 list_add_tail(&cursor->s_sibling, p);
1662 spin_unlock(&configfs_dirent_lock);
1663 }
1664 }
1665 mutex_unlock(&dentry->d_inode->i_mutex);
1666 return offset;
1667}
1668
1669const struct file_operations configfs_dir_operations = {
1670 .open = configfs_dir_open,
1671 .release = configfs_dir_close,
1672 .llseek = configfs_dir_lseek,
1673 .read = generic_read_dir,
1674 .readdir = configfs_readdir,
1675};
1676
1677int configfs_register_subsystem(struct configfs_subsystem *subsys)
1678{
1679 int err;
1680 struct config_group *group = &subsys->su_group;
1681 struct qstr name;
1682 struct dentry *dentry;
1683 struct configfs_dirent *sd;
1684
1685 err = configfs_pin_fs();
1686 if (err)
1687 return err;
1688
1689 if (!group->cg_item.ci_name)
1690 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1691
1692 sd = configfs_sb->s_root->d_fsdata;
1693 link_group(to_config_group(sd->s_element), group);
1694
1695 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1696 I_MUTEX_PARENT);
1697
1698 name.name = group->cg_item.ci_name;
1699 name.len = strlen(name.name);
1700 name.hash = full_name_hash(name.name, name.len);
1701
1702 err = -ENOMEM;
1703 dentry = d_alloc(configfs_sb->s_root, &name);
1704 if (dentry) {
1705 d_add(dentry, NULL);
1706
1707 err = configfs_attach_group(sd->s_element, &group->cg_item,
1708 dentry);
1709 if (err) {
1710 BUG_ON(dentry->d_inode);
1711 d_drop(dentry);
1712 dput(dentry);
1713 } else {
1714 spin_lock(&configfs_dirent_lock);
1715 configfs_dir_set_ready(dentry->d_fsdata);
1716 spin_unlock(&configfs_dirent_lock);
1717 }
1718 }
1719
1720 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1721
1722 if (err) {
1723 unlink_group(group);
1724 configfs_release_fs();
1725 }
1726
1727 return err;
1728}
1729
1730void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1731{
1732 struct config_group *group = &subsys->su_group;
1733 struct dentry *dentry = group->cg_item.ci_dentry;
1734
1735 if (dentry->d_parent != configfs_sb->s_root) {
1736 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1737 return;
1738 }
1739
1740 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1741 I_MUTEX_PARENT);
1742 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1743 mutex_lock(&configfs_symlink_mutex);
1744 spin_lock(&configfs_dirent_lock);
1745 if (configfs_detach_prep(dentry, NULL)) {
1746 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1747 }
1748 spin_unlock(&configfs_dirent_lock);
1749 mutex_unlock(&configfs_symlink_mutex);
1750 configfs_detach_group(&group->cg_item);
1751 dentry->d_inode->i_flags |= S_DEAD;
1752 dont_mount(dentry);
1753 mutex_unlock(&dentry->d_inode->i_mutex);
1754
1755 d_delete(dentry);
1756
1757 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1758
1759 dput(dentry);
1760
1761 unlink_group(group);
1762 configfs_release_fs();
1763}
1764
1765EXPORT_SYMBOL(configfs_register_subsystem);
1766EXPORT_SYMBOL(configfs_unregister_subsystem);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* -*- mode: c; c-basic-offset: 8; -*-
3 * vim: noexpandtab sw=8 ts=8 sts=0:
4 *
5 * dir.c - Operations for configfs directories.
6 *
7 * Based on sysfs:
8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
9 *
10 * configfs Copyright (C) 2005 Oracle. All rights reserved.
11 */
12
13#undef DEBUG
14
15#include <linux/fs.h>
16#include <linux/fsnotify.h>
17#include <linux/mount.h>
18#include <linux/module.h>
19#include <linux/slab.h>
20#include <linux/err.h>
21
22#include <linux/configfs.h>
23#include "configfs_internal.h"
24
25/*
26 * Protects mutations of configfs_dirent linkage together with proper i_mutex
27 * Also protects mutations of symlinks linkage to target configfs_dirent
28 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
29 * and configfs_dirent_lock locked, in that order.
30 * This allows one to safely traverse configfs_dirent trees and symlinks without
31 * having to lock inodes.
32 *
33 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
34 * unlocked is not reliable unless in detach_groups() called from
35 * rmdir()/unregister() and from configfs_attach_group()
36 */
37DEFINE_SPINLOCK(configfs_dirent_lock);
38
39static void configfs_d_iput(struct dentry * dentry,
40 struct inode * inode)
41{
42 struct configfs_dirent *sd = dentry->d_fsdata;
43
44 if (sd) {
45 /* Coordinate with configfs_readdir */
46 spin_lock(&configfs_dirent_lock);
47 /*
48 * Set sd->s_dentry to null only when this dentry is the one
49 * that is going to be killed. Otherwise configfs_d_iput may
50 * run just after configfs_attach_attr and set sd->s_dentry to
51 * NULL even it's still in use.
52 */
53 if (sd->s_dentry == dentry)
54 sd->s_dentry = NULL;
55
56 spin_unlock(&configfs_dirent_lock);
57 configfs_put(sd);
58 }
59 iput(inode);
60}
61
62const struct dentry_operations configfs_dentry_ops = {
63 .d_iput = configfs_d_iput,
64 .d_delete = always_delete_dentry,
65};
66
67#ifdef CONFIG_LOCKDEP
68
69/*
70 * Helpers to make lockdep happy with our recursive locking of default groups'
71 * inodes (see configfs_attach_group() and configfs_detach_group()).
72 * We put default groups i_mutexes in separate classes according to their depth
73 * from the youngest non-default group ancestor.
74 *
75 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
76 * groups A/B and A/C will have their inode's mutex in class
77 * default_group_class[0], and default group A/C/D will be in
78 * default_group_class[1].
79 *
80 * The lock classes are declared and assigned in inode.c, according to the
81 * s_depth value.
82 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
83 * default groups, and reset to -1 when all default groups are attached. During
84 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
85 * inode's mutex is set to default_group_class[s_depth - 1].
86 */
87
88static void configfs_init_dirent_depth(struct configfs_dirent *sd)
89{
90 sd->s_depth = -1;
91}
92
93static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
94 struct configfs_dirent *sd)
95{
96 int parent_depth = parent_sd->s_depth;
97
98 if (parent_depth >= 0)
99 sd->s_depth = parent_depth + 1;
100}
101
102static void
103configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
104{
105 /*
106 * item's i_mutex class is already setup, so s_depth is now only
107 * used to set new sub-directories s_depth, which is always done
108 * with item's i_mutex locked.
109 */
110 /*
111 * sd->s_depth == -1 iff we are a non default group.
112 * else (we are a default group) sd->s_depth > 0 (see
113 * create_dir()).
114 */
115 if (sd->s_depth == -1)
116 /*
117 * We are a non default group and we are going to create
118 * default groups.
119 */
120 sd->s_depth = 0;
121}
122
123static void
124configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
125{
126 /* We will not create default groups anymore. */
127 sd->s_depth = -1;
128}
129
130#else /* CONFIG_LOCKDEP */
131
132static void configfs_init_dirent_depth(struct configfs_dirent *sd)
133{
134}
135
136static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
137 struct configfs_dirent *sd)
138{
139}
140
141static void
142configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
143{
144}
145
146static void
147configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
148{
149}
150
151#endif /* CONFIG_LOCKDEP */
152
153static struct configfs_fragment *new_fragment(void)
154{
155 struct configfs_fragment *p;
156
157 p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);
158 if (p) {
159 atomic_set(&p->frag_count, 1);
160 init_rwsem(&p->frag_sem);
161 p->frag_dead = false;
162 }
163 return p;
164}
165
166void put_fragment(struct configfs_fragment *frag)
167{
168 if (frag && atomic_dec_and_test(&frag->frag_count))
169 kfree(frag);
170}
171
172struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
173{
174 if (likely(frag))
175 atomic_inc(&frag->frag_count);
176 return frag;
177}
178
179/*
180 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
181 */
182static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
183 void *element, int type,
184 struct configfs_fragment *frag)
185{
186 struct configfs_dirent * sd;
187
188 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
189 if (!sd)
190 return ERR_PTR(-ENOMEM);
191
192 atomic_set(&sd->s_count, 1);
193 INIT_LIST_HEAD(&sd->s_children);
194 sd->s_element = element;
195 sd->s_type = type;
196 configfs_init_dirent_depth(sd);
197 spin_lock(&configfs_dirent_lock);
198 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
199 spin_unlock(&configfs_dirent_lock);
200 kmem_cache_free(configfs_dir_cachep, sd);
201 return ERR_PTR(-ENOENT);
202 }
203 sd->s_frag = get_fragment(frag);
204 list_add(&sd->s_sibling, &parent_sd->s_children);
205 spin_unlock(&configfs_dirent_lock);
206
207 return sd;
208}
209
210/*
211 *
212 * Return -EEXIST if there is already a configfs element with the same
213 * name for the same parent.
214 *
215 * called with parent inode's i_mutex held
216 */
217static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
218 const unsigned char *new)
219{
220 struct configfs_dirent * sd;
221
222 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
223 if (sd->s_element) {
224 const unsigned char *existing = configfs_get_name(sd);
225 if (strcmp(existing, new))
226 continue;
227 else
228 return -EEXIST;
229 }
230 }
231
232 return 0;
233}
234
235
236int configfs_make_dirent(struct configfs_dirent * parent_sd,
237 struct dentry * dentry, void * element,
238 umode_t mode, int type, struct configfs_fragment *frag)
239{
240 struct configfs_dirent * sd;
241
242 sd = configfs_new_dirent(parent_sd, element, type, frag);
243 if (IS_ERR(sd))
244 return PTR_ERR(sd);
245
246 sd->s_mode = mode;
247 sd->s_dentry = dentry;
248 if (dentry)
249 dentry->d_fsdata = configfs_get(sd);
250
251 return 0;
252}
253
254static void configfs_remove_dirent(struct dentry *dentry)
255{
256 struct configfs_dirent *sd = dentry->d_fsdata;
257
258 if (!sd)
259 return;
260 spin_lock(&configfs_dirent_lock);
261 list_del_init(&sd->s_sibling);
262 spin_unlock(&configfs_dirent_lock);
263 configfs_put(sd);
264}
265
266/**
267 * configfs_create_dir - create a directory for an config_item.
268 * @item: config_itemwe're creating directory for.
269 * @dentry: config_item's dentry.
270 *
271 * Note: user-created entries won't be allowed under this new directory
272 * until it is validated by configfs_dir_set_ready()
273 */
274
275static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
276 struct configfs_fragment *frag)
277{
278 int error;
279 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
280 struct dentry *p = dentry->d_parent;
281 struct inode *inode;
282
283 BUG_ON(!item);
284
285 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
286 if (unlikely(error))
287 return error;
288
289 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
290 CONFIGFS_DIR | CONFIGFS_USET_CREATING,
291 frag);
292 if (unlikely(error))
293 return error;
294
295 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
296 inode = configfs_create(dentry, mode);
297 if (IS_ERR(inode))
298 goto out_remove;
299
300 inode->i_op = &configfs_dir_inode_operations;
301 inode->i_fop = &configfs_dir_operations;
302 /* directory inodes start off with i_nlink == 2 (for "." entry) */
303 inc_nlink(inode);
304 d_instantiate(dentry, inode);
305 /* already hashed */
306 dget(dentry); /* pin directory dentries in core */
307 inc_nlink(d_inode(p));
308 item->ci_dentry = dentry;
309 return 0;
310
311out_remove:
312 configfs_remove_dirent(dentry);
313 return PTR_ERR(inode);
314}
315
316/*
317 * Allow userspace to create new entries under a new directory created with
318 * configfs_create_dir(), and under all of its chidlren directories recursively.
319 * @sd configfs_dirent of the new directory to validate
320 *
321 * Caller must hold configfs_dirent_lock.
322 */
323static void configfs_dir_set_ready(struct configfs_dirent *sd)
324{
325 struct configfs_dirent *child_sd;
326
327 sd->s_type &= ~CONFIGFS_USET_CREATING;
328 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
329 if (child_sd->s_type & CONFIGFS_USET_CREATING)
330 configfs_dir_set_ready(child_sd);
331}
332
333/*
334 * Check that a directory does not belong to a directory hierarchy being
335 * attached and not validated yet.
336 * @sd configfs_dirent of the directory to check
337 *
338 * @return non-zero iff the directory was validated
339 *
340 * Note: takes configfs_dirent_lock, so the result may change from false to true
341 * in two consecutive calls, but never from true to false.
342 */
343int configfs_dirent_is_ready(struct configfs_dirent *sd)
344{
345 int ret;
346
347 spin_lock(&configfs_dirent_lock);
348 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
349 spin_unlock(&configfs_dirent_lock);
350
351 return ret;
352}
353
354int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,
355 struct dentry *dentry, char *body)
356{
357 int err = 0;
358 umode_t mode = S_IFLNK | S_IRWXUGO;
359 struct configfs_dirent *p = parent->d_fsdata;
360 struct inode *inode;
361
362 err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK,
363 p->s_frag);
364 if (err)
365 return err;
366
367 inode = configfs_create(dentry, mode);
368 if (IS_ERR(inode))
369 goto out_remove;
370
371 inode->i_link = body;
372 inode->i_op = &configfs_symlink_inode_operations;
373 d_instantiate(dentry, inode);
374 dget(dentry); /* pin link dentries in core */
375 return 0;
376
377out_remove:
378 configfs_remove_dirent(dentry);
379 return PTR_ERR(inode);
380}
381
382static void remove_dir(struct dentry * d)
383{
384 struct dentry * parent = dget(d->d_parent);
385
386 configfs_remove_dirent(d);
387
388 if (d_really_is_positive(d))
389 simple_rmdir(d_inode(parent),d);
390
391 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
392
393 dput(parent);
394}
395
396/**
397 * configfs_remove_dir - remove an config_item's directory.
398 * @item: config_item we're removing.
399 *
400 * The only thing special about this is that we remove any files in
401 * the directory before we remove the directory, and we've inlined
402 * what used to be configfs_rmdir() below, instead of calling separately.
403 *
404 * Caller holds the mutex of the item's inode
405 */
406
407static void configfs_remove_dir(struct config_item * item)
408{
409 struct dentry * dentry = dget(item->ci_dentry);
410
411 if (!dentry)
412 return;
413
414 remove_dir(dentry);
415 /**
416 * Drop reference from dget() on entrance.
417 */
418 dput(dentry);
419}
420
421
422/* attaches attribute's configfs_dirent to the dentry corresponding to the
423 * attribute file
424 */
425static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
426{
427 struct configfs_attribute * attr = sd->s_element;
428 struct inode *inode;
429
430 spin_lock(&configfs_dirent_lock);
431 dentry->d_fsdata = configfs_get(sd);
432 sd->s_dentry = dentry;
433 spin_unlock(&configfs_dirent_lock);
434
435 inode = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG);
436 if (IS_ERR(inode)) {
437 configfs_put(sd);
438 return PTR_ERR(inode);
439 }
440 if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
441 inode->i_size = 0;
442 inode->i_fop = &configfs_bin_file_operations;
443 } else {
444 inode->i_size = PAGE_SIZE;
445 inode->i_fop = &configfs_file_operations;
446 }
447 d_add(dentry, inode);
448 return 0;
449}
450
451static struct dentry * configfs_lookup(struct inode *dir,
452 struct dentry *dentry,
453 unsigned int flags)
454{
455 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
456 struct configfs_dirent * sd;
457 int found = 0;
458 int err;
459
460 /*
461 * Fake invisibility if dir belongs to a group/default groups hierarchy
462 * being attached
463 *
464 * This forbids userspace to read/write attributes of items which may
465 * not complete their initialization, since the dentries of the
466 * attributes won't be instantiated.
467 */
468 err = -ENOENT;
469 if (!configfs_dirent_is_ready(parent_sd))
470 goto out;
471
472 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
473 if (sd->s_type & CONFIGFS_NOT_PINNED) {
474 const unsigned char * name = configfs_get_name(sd);
475
476 if (strcmp(name, dentry->d_name.name))
477 continue;
478
479 found = 1;
480 err = configfs_attach_attr(sd, dentry);
481 break;
482 }
483 }
484
485 if (!found) {
486 /*
487 * If it doesn't exist and it isn't a NOT_PINNED item,
488 * it must be negative.
489 */
490 if (dentry->d_name.len > NAME_MAX)
491 return ERR_PTR(-ENAMETOOLONG);
492 d_add(dentry, NULL);
493 return NULL;
494 }
495
496out:
497 return ERR_PTR(err);
498}
499
500/*
501 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
502 * attributes and are removed by rmdir(). We recurse, setting
503 * CONFIGFS_USET_DROPPING on all children that are candidates for
504 * default detach.
505 * If there is an error, the caller will reset the flags via
506 * configfs_detach_rollback().
507 */
508static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
509{
510 struct configfs_dirent *parent_sd = dentry->d_fsdata;
511 struct configfs_dirent *sd;
512 int ret;
513
514 /* Mark that we're trying to drop the group */
515 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
516
517 ret = -EBUSY;
518 if (parent_sd->s_links)
519 goto out;
520
521 ret = 0;
522 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
523 if (!sd->s_element ||
524 (sd->s_type & CONFIGFS_NOT_PINNED))
525 continue;
526 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
527 /* Abort if racing with mkdir() */
528 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
529 if (wait)
530 *wait= dget(sd->s_dentry);
531 return -EAGAIN;
532 }
533
534 /*
535 * Yup, recursive. If there's a problem, blame
536 * deep nesting of default_groups
537 */
538 ret = configfs_detach_prep(sd->s_dentry, wait);
539 if (!ret)
540 continue;
541 } else
542 ret = -ENOTEMPTY;
543
544 break;
545 }
546
547out:
548 return ret;
549}
550
551/*
552 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
553 * set.
554 */
555static void configfs_detach_rollback(struct dentry *dentry)
556{
557 struct configfs_dirent *parent_sd = dentry->d_fsdata;
558 struct configfs_dirent *sd;
559
560 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
561
562 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
563 if (sd->s_type & CONFIGFS_USET_DEFAULT)
564 configfs_detach_rollback(sd->s_dentry);
565}
566
567static void detach_attrs(struct config_item * item)
568{
569 struct dentry * dentry = dget(item->ci_dentry);
570 struct configfs_dirent * parent_sd;
571 struct configfs_dirent * sd, * tmp;
572
573 if (!dentry)
574 return;
575
576 pr_debug("configfs %s: dropping attrs for dir\n",
577 dentry->d_name.name);
578
579 parent_sd = dentry->d_fsdata;
580 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
581 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
582 continue;
583 spin_lock(&configfs_dirent_lock);
584 list_del_init(&sd->s_sibling);
585 spin_unlock(&configfs_dirent_lock);
586 configfs_drop_dentry(sd, dentry);
587 configfs_put(sd);
588 }
589
590 /**
591 * Drop reference from dget() on entrance.
592 */
593 dput(dentry);
594}
595
596static int populate_attrs(struct config_item *item)
597{
598 const struct config_item_type *t = item->ci_type;
599 struct configfs_attribute *attr;
600 struct configfs_bin_attribute *bin_attr;
601 int error = 0;
602 int i;
603
604 if (!t)
605 return -EINVAL;
606 if (t->ct_attrs) {
607 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
608 if ((error = configfs_create_file(item, attr)))
609 break;
610 }
611 }
612 if (t->ct_bin_attrs) {
613 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
614 error = configfs_create_bin_file(item, bin_attr);
615 if (error)
616 break;
617 }
618 }
619
620 if (error)
621 detach_attrs(item);
622
623 return error;
624}
625
626static int configfs_attach_group(struct config_item *parent_item,
627 struct config_item *item,
628 struct dentry *dentry,
629 struct configfs_fragment *frag);
630static void configfs_detach_group(struct config_item *item);
631
632static void detach_groups(struct config_group *group)
633{
634 struct dentry * dentry = dget(group->cg_item.ci_dentry);
635 struct dentry *child;
636 struct configfs_dirent *parent_sd;
637 struct configfs_dirent *sd, *tmp;
638
639 if (!dentry)
640 return;
641
642 parent_sd = dentry->d_fsdata;
643 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
644 if (!sd->s_element ||
645 !(sd->s_type & CONFIGFS_USET_DEFAULT))
646 continue;
647
648 child = sd->s_dentry;
649
650 inode_lock(d_inode(child));
651
652 configfs_detach_group(sd->s_element);
653 d_inode(child)->i_flags |= S_DEAD;
654 dont_mount(child);
655
656 inode_unlock(d_inode(child));
657
658 d_delete(child);
659 dput(child);
660 }
661
662 /**
663 * Drop reference from dget() on entrance.
664 */
665 dput(dentry);
666}
667
668/*
669 * This fakes mkdir(2) on a default_groups[] entry. It
670 * creates a dentry, attachs it, and then does fixup
671 * on the sd->s_type.
672 *
673 * We could, perhaps, tweak our parent's ->mkdir for a minute and
674 * try using vfs_mkdir. Just a thought.
675 */
676static int create_default_group(struct config_group *parent_group,
677 struct config_group *group,
678 struct configfs_fragment *frag)
679{
680 int ret;
681 struct configfs_dirent *sd;
682 /* We trust the caller holds a reference to parent */
683 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
684
685 if (!group->cg_item.ci_name)
686 group->cg_item.ci_name = group->cg_item.ci_namebuf;
687
688 ret = -ENOMEM;
689 child = d_alloc_name(parent, group->cg_item.ci_name);
690 if (child) {
691 d_add(child, NULL);
692
693 ret = configfs_attach_group(&parent_group->cg_item,
694 &group->cg_item, child, frag);
695 if (!ret) {
696 sd = child->d_fsdata;
697 sd->s_type |= CONFIGFS_USET_DEFAULT;
698 } else {
699 BUG_ON(d_inode(child));
700 d_drop(child);
701 dput(child);
702 }
703 }
704
705 return ret;
706}
707
708static int populate_groups(struct config_group *group,
709 struct configfs_fragment *frag)
710{
711 struct config_group *new_group;
712 int ret = 0;
713
714 list_for_each_entry(new_group, &group->default_groups, group_entry) {
715 ret = create_default_group(group, new_group, frag);
716 if (ret) {
717 detach_groups(group);
718 break;
719 }
720 }
721
722 return ret;
723}
724
725void configfs_remove_default_groups(struct config_group *group)
726{
727 struct config_group *g, *n;
728
729 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
730 list_del(&g->group_entry);
731 config_item_put(&g->cg_item);
732 }
733}
734EXPORT_SYMBOL(configfs_remove_default_groups);
735
736/*
737 * All of link_obj/unlink_obj/link_group/unlink_group require that
738 * subsys->su_mutex is held.
739 */
740
741static void unlink_obj(struct config_item *item)
742{
743 struct config_group *group;
744
745 group = item->ci_group;
746 if (group) {
747 list_del_init(&item->ci_entry);
748
749 item->ci_group = NULL;
750 item->ci_parent = NULL;
751
752 /* Drop the reference for ci_entry */
753 config_item_put(item);
754
755 /* Drop the reference for ci_parent */
756 config_group_put(group);
757 }
758}
759
760static void link_obj(struct config_item *parent_item, struct config_item *item)
761{
762 /*
763 * Parent seems redundant with group, but it makes certain
764 * traversals much nicer.
765 */
766 item->ci_parent = parent_item;
767
768 /*
769 * We hold a reference on the parent for the child's ci_parent
770 * link.
771 */
772 item->ci_group = config_group_get(to_config_group(parent_item));
773 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
774
775 /*
776 * We hold a reference on the child for ci_entry on the parent's
777 * cg_children
778 */
779 config_item_get(item);
780}
781
782static void unlink_group(struct config_group *group)
783{
784 struct config_group *new_group;
785
786 list_for_each_entry(new_group, &group->default_groups, group_entry)
787 unlink_group(new_group);
788
789 group->cg_subsys = NULL;
790 unlink_obj(&group->cg_item);
791}
792
793static void link_group(struct config_group *parent_group, struct config_group *group)
794{
795 struct config_group *new_group;
796 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
797
798 link_obj(&parent_group->cg_item, &group->cg_item);
799
800 if (parent_group->cg_subsys)
801 subsys = parent_group->cg_subsys;
802 else if (configfs_is_root(&parent_group->cg_item))
803 subsys = to_configfs_subsystem(group);
804 else
805 BUG();
806 group->cg_subsys = subsys;
807
808 list_for_each_entry(new_group, &group->default_groups, group_entry)
809 link_group(group, new_group);
810}
811
812/*
813 * The goal is that configfs_attach_item() (and
814 * configfs_attach_group()) can be called from either the VFS or this
815 * module. That is, they assume that the items have been created,
816 * the dentry allocated, and the dcache is all ready to go.
817 *
818 * If they fail, they must clean up after themselves as if they
819 * had never been called. The caller (VFS or local function) will
820 * handle cleaning up the dcache bits.
821 *
822 * configfs_detach_group() and configfs_detach_item() behave similarly on
823 * the way out. They assume that the proper semaphores are held, they
824 * clean up the configfs items, and they expect their callers will
825 * handle the dcache bits.
826 */
827static int configfs_attach_item(struct config_item *parent_item,
828 struct config_item *item,
829 struct dentry *dentry,
830 struct configfs_fragment *frag)
831{
832 int ret;
833
834 ret = configfs_create_dir(item, dentry, frag);
835 if (!ret) {
836 ret = populate_attrs(item);
837 if (ret) {
838 /*
839 * We are going to remove an inode and its dentry but
840 * the VFS may already have hit and used them. Thus,
841 * we must lock them as rmdir() would.
842 */
843 inode_lock(d_inode(dentry));
844 configfs_remove_dir(item);
845 d_inode(dentry)->i_flags |= S_DEAD;
846 dont_mount(dentry);
847 inode_unlock(d_inode(dentry));
848 d_delete(dentry);
849 }
850 }
851
852 return ret;
853}
854
855/* Caller holds the mutex of the item's inode */
856static void configfs_detach_item(struct config_item *item)
857{
858 detach_attrs(item);
859 configfs_remove_dir(item);
860}
861
862static int configfs_attach_group(struct config_item *parent_item,
863 struct config_item *item,
864 struct dentry *dentry,
865 struct configfs_fragment *frag)
866{
867 int ret;
868 struct configfs_dirent *sd;
869
870 ret = configfs_attach_item(parent_item, item, dentry, frag);
871 if (!ret) {
872 sd = dentry->d_fsdata;
873 sd->s_type |= CONFIGFS_USET_DIR;
874
875 /*
876 * FYI, we're faking mkdir in populate_groups()
877 * We must lock the group's inode to avoid races with the VFS
878 * which can already hit the inode and try to add/remove entries
879 * under it.
880 *
881 * We must also lock the inode to remove it safely in case of
882 * error, as rmdir() would.
883 */
884 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
885 configfs_adjust_dir_dirent_depth_before_populate(sd);
886 ret = populate_groups(to_config_group(item), frag);
887 if (ret) {
888 configfs_detach_item(item);
889 d_inode(dentry)->i_flags |= S_DEAD;
890 dont_mount(dentry);
891 }
892 configfs_adjust_dir_dirent_depth_after_populate(sd);
893 inode_unlock(d_inode(dentry));
894 if (ret)
895 d_delete(dentry);
896 }
897
898 return ret;
899}
900
901/* Caller holds the mutex of the group's inode */
902static void configfs_detach_group(struct config_item *item)
903{
904 detach_groups(to_config_group(item));
905 configfs_detach_item(item);
906}
907
908/*
909 * After the item has been detached from the filesystem view, we are
910 * ready to tear it out of the hierarchy. Notify the client before
911 * we do that so they can perform any cleanup that requires
912 * navigating the hierarchy. A client does not need to provide this
913 * callback. The subsystem semaphore MUST be held by the caller, and
914 * references must be valid for both items. It also assumes the
915 * caller has validated ci_type.
916 */
917static void client_disconnect_notify(struct config_item *parent_item,
918 struct config_item *item)
919{
920 const struct config_item_type *type;
921
922 type = parent_item->ci_type;
923 BUG_ON(!type);
924
925 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
926 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
927 item);
928}
929
930/*
931 * Drop the initial reference from make_item()/make_group()
932 * This function assumes that reference is held on item
933 * and that item holds a valid reference to the parent. Also, it
934 * assumes the caller has validated ci_type.
935 */
936static void client_drop_item(struct config_item *parent_item,
937 struct config_item *item)
938{
939 const struct config_item_type *type;
940
941 type = parent_item->ci_type;
942 BUG_ON(!type);
943
944 /*
945 * If ->drop_item() exists, it is responsible for the
946 * config_item_put().
947 */
948 if (type->ct_group_ops && type->ct_group_ops->drop_item)
949 type->ct_group_ops->drop_item(to_config_group(parent_item),
950 item);
951 else
952 config_item_put(item);
953}
954
955#ifdef DEBUG
956static void configfs_dump_one(struct configfs_dirent *sd, int level)
957{
958 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
959
960#define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
961 type_print(CONFIGFS_ROOT);
962 type_print(CONFIGFS_DIR);
963 type_print(CONFIGFS_ITEM_ATTR);
964 type_print(CONFIGFS_ITEM_LINK);
965 type_print(CONFIGFS_USET_DIR);
966 type_print(CONFIGFS_USET_DEFAULT);
967 type_print(CONFIGFS_USET_DROPPING);
968#undef type_print
969}
970
971static int configfs_dump(struct configfs_dirent *sd, int level)
972{
973 struct configfs_dirent *child_sd;
974 int ret = 0;
975
976 configfs_dump_one(sd, level);
977
978 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
979 return 0;
980
981 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
982 ret = configfs_dump(child_sd, level + 2);
983 if (ret)
984 break;
985 }
986
987 return ret;
988}
989#endif
990
991
992/*
993 * configfs_depend_item() and configfs_undepend_item()
994 *
995 * WARNING: Do not call these from a configfs callback!
996 *
997 * This describes these functions and their helpers.
998 *
999 * Allow another kernel system to depend on a config_item. If this
1000 * happens, the item cannot go away until the dependent can live without
1001 * it. The idea is to give client modules as simple an interface as
1002 * possible. When a system asks them to depend on an item, they just
1003 * call configfs_depend_item(). If the item is live and the client
1004 * driver is in good shape, we'll happily do the work for them.
1005 *
1006 * Why is the locking complex? Because configfs uses the VFS to handle
1007 * all locking, but this function is called outside the normal
1008 * VFS->configfs path. So it must take VFS locks to prevent the
1009 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1010 * why you can't call these functions underneath configfs callbacks.
1011 *
1012 * Note, btw, that this can be called at *any* time, even when a configfs
1013 * subsystem isn't registered, or when configfs is loading or unloading.
1014 * Just like configfs_register_subsystem(). So we take the same
1015 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1016 * If we can find the target item in the
1017 * configfs tree, it must be part of the subsystem tree as well, so we
1018 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1019 * locking out mkdir() and rmdir(), who might be racing us.
1020 */
1021
1022/*
1023 * configfs_depend_prep()
1024 *
1025 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1026 * attributes. This is similar but not the same to configfs_detach_prep().
1027 * Note that configfs_detach_prep() expects the parent to be locked when it
1028 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1029 * do that so we can unlock it if we find nothing.
1030 *
1031 * Here we do a depth-first search of the dentry hierarchy looking for
1032 * our object.
1033 * We deliberately ignore items tagged as dropping since they are virtually
1034 * dead, as well as items in the middle of attachment since they virtually
1035 * do not exist yet. This completes the locking out of racing mkdir() and
1036 * rmdir().
1037 * Note: subdirectories in the middle of attachment start with s_type =
1038 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1039 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1040 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1041 *
1042 * If the target is not found, -ENOENT is bubbled up.
1043 *
1044 * This adds a requirement that all config_items be unique!
1045 *
1046 * This is recursive. There isn't
1047 * much on the stack, though, so folks that need this function - be careful
1048 * about your stack! Patches will be accepted to make it iterative.
1049 */
1050static int configfs_depend_prep(struct dentry *origin,
1051 struct config_item *target)
1052{
1053 struct configfs_dirent *child_sd, *sd;
1054 int ret = 0;
1055
1056 BUG_ON(!origin || !origin->d_fsdata);
1057 sd = origin->d_fsdata;
1058
1059 if (sd->s_element == target) /* Boo-yah */
1060 goto out;
1061
1062 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1063 if ((child_sd->s_type & CONFIGFS_DIR) &&
1064 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1065 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1066 ret = configfs_depend_prep(child_sd->s_dentry,
1067 target);
1068 if (!ret)
1069 goto out; /* Child path boo-yah */
1070 }
1071 }
1072
1073 /* We looped all our children and didn't find target */
1074 ret = -ENOENT;
1075
1076out:
1077 return ret;
1078}
1079
1080static int configfs_do_depend_item(struct dentry *subsys_dentry,
1081 struct config_item *target)
1082{
1083 struct configfs_dirent *p;
1084 int ret;
1085
1086 spin_lock(&configfs_dirent_lock);
1087 /* Scan the tree, return 0 if found */
1088 ret = configfs_depend_prep(subsys_dentry, target);
1089 if (ret)
1090 goto out_unlock_dirent_lock;
1091
1092 /*
1093 * We are sure that the item is not about to be removed by rmdir(), and
1094 * not in the middle of attachment by mkdir().
1095 */
1096 p = target->ci_dentry->d_fsdata;
1097 p->s_dependent_count += 1;
1098
1099out_unlock_dirent_lock:
1100 spin_unlock(&configfs_dirent_lock);
1101
1102 return ret;
1103}
1104
1105static inline struct configfs_dirent *
1106configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1107 struct config_item *subsys_item)
1108{
1109 struct configfs_dirent *p;
1110 struct configfs_dirent *ret = NULL;
1111
1112 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1113 if (p->s_type & CONFIGFS_DIR &&
1114 p->s_element == subsys_item) {
1115 ret = p;
1116 break;
1117 }
1118 }
1119
1120 return ret;
1121}
1122
1123
1124int configfs_depend_item(struct configfs_subsystem *subsys,
1125 struct config_item *target)
1126{
1127 int ret;
1128 struct configfs_dirent *subsys_sd;
1129 struct config_item *s_item = &subsys->su_group.cg_item;
1130 struct dentry *root;
1131
1132 /*
1133 * Pin the configfs filesystem. This means we can safely access
1134 * the root of the configfs filesystem.
1135 */
1136 root = configfs_pin_fs();
1137 if (IS_ERR(root))
1138 return PTR_ERR(root);
1139
1140 /*
1141 * Next, lock the root directory. We're going to check that the
1142 * subsystem is really registered, and so we need to lock out
1143 * configfs_[un]register_subsystem().
1144 */
1145 inode_lock(d_inode(root));
1146
1147 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1148 if (!subsys_sd) {
1149 ret = -ENOENT;
1150 goto out_unlock_fs;
1151 }
1152
1153 /* Ok, now we can trust subsys/s_item */
1154 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1155
1156out_unlock_fs:
1157 inode_unlock(d_inode(root));
1158
1159 /*
1160 * If we succeeded, the fs is pinned via other methods. If not,
1161 * we're done with it anyway. So release_fs() is always right.
1162 */
1163 configfs_release_fs();
1164
1165 return ret;
1166}
1167EXPORT_SYMBOL(configfs_depend_item);
1168
1169/*
1170 * Release the dependent linkage. This is much simpler than
1171 * configfs_depend_item() because we know that that the client driver is
1172 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1173 */
1174void configfs_undepend_item(struct config_item *target)
1175{
1176 struct configfs_dirent *sd;
1177
1178 /*
1179 * Since we can trust everything is pinned, we just need
1180 * configfs_dirent_lock.
1181 */
1182 spin_lock(&configfs_dirent_lock);
1183
1184 sd = target->ci_dentry->d_fsdata;
1185 BUG_ON(sd->s_dependent_count < 1);
1186
1187 sd->s_dependent_count -= 1;
1188
1189 /*
1190 * After this unlock, we cannot trust the item to stay alive!
1191 * DO NOT REFERENCE item after this unlock.
1192 */
1193 spin_unlock(&configfs_dirent_lock);
1194}
1195EXPORT_SYMBOL(configfs_undepend_item);
1196
1197/*
1198 * caller_subsys is a caller's subsystem not target's. This is used to
1199 * determine if we should lock root and check subsys or not. When we are
1200 * in the same subsystem as our target there is no need to do locking as
1201 * we know that subsys is valid and is not unregistered during this function
1202 * as we are called from callback of one of his children and VFS holds a lock
1203 * on some inode. Otherwise we have to lock our root to ensure that target's
1204 * subsystem it is not unregistered during this function.
1205 */
1206int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1207 struct config_item *target)
1208{
1209 struct configfs_subsystem *target_subsys;
1210 struct config_group *root, *parent;
1211 struct configfs_dirent *subsys_sd;
1212 int ret = -ENOENT;
1213
1214 /* Disallow this function for configfs root */
1215 if (configfs_is_root(target))
1216 return -EINVAL;
1217
1218 parent = target->ci_group;
1219 /*
1220 * This may happen when someone is trying to depend root
1221 * directory of some subsystem
1222 */
1223 if (configfs_is_root(&parent->cg_item)) {
1224 target_subsys = to_configfs_subsystem(to_config_group(target));
1225 root = parent;
1226 } else {
1227 target_subsys = parent->cg_subsys;
1228 /* Find a cofnigfs root as we may need it for locking */
1229 for (root = parent; !configfs_is_root(&root->cg_item);
1230 root = root->cg_item.ci_group)
1231 ;
1232 }
1233
1234 if (target_subsys != caller_subsys) {
1235 /*
1236 * We are in other configfs subsystem, so we have to do
1237 * additional locking to prevent other subsystem from being
1238 * unregistered
1239 */
1240 inode_lock(d_inode(root->cg_item.ci_dentry));
1241
1242 /*
1243 * As we are trying to depend item from other subsystem
1244 * we have to check if this subsystem is still registered
1245 */
1246 subsys_sd = configfs_find_subsys_dentry(
1247 root->cg_item.ci_dentry->d_fsdata,
1248 &target_subsys->su_group.cg_item);
1249 if (!subsys_sd)
1250 goto out_root_unlock;
1251 } else {
1252 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1253 }
1254
1255 /* Now we can execute core of depend item */
1256 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1257
1258 if (target_subsys != caller_subsys)
1259out_root_unlock:
1260 /*
1261 * We were called from subsystem other than our target so we
1262 * took some locks so now it's time to release them
1263 */
1264 inode_unlock(d_inode(root->cg_item.ci_dentry));
1265
1266 return ret;
1267}
1268EXPORT_SYMBOL(configfs_depend_item_unlocked);
1269
1270static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1271{
1272 int ret = 0;
1273 int module_got = 0;
1274 struct config_group *group = NULL;
1275 struct config_item *item = NULL;
1276 struct config_item *parent_item;
1277 struct configfs_subsystem *subsys;
1278 struct configfs_dirent *sd;
1279 const struct config_item_type *type;
1280 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1281 struct configfs_fragment *frag;
1282 char *name;
1283
1284 sd = dentry->d_parent->d_fsdata;
1285
1286 /*
1287 * Fake invisibility if dir belongs to a group/default groups hierarchy
1288 * being attached
1289 */
1290 if (!configfs_dirent_is_ready(sd)) {
1291 ret = -ENOENT;
1292 goto out;
1293 }
1294
1295 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1296 ret = -EPERM;
1297 goto out;
1298 }
1299
1300 frag = new_fragment();
1301 if (!frag) {
1302 ret = -ENOMEM;
1303 goto out;
1304 }
1305
1306 /* Get a working ref for the duration of this function */
1307 parent_item = configfs_get_config_item(dentry->d_parent);
1308 type = parent_item->ci_type;
1309 subsys = to_config_group(parent_item)->cg_subsys;
1310 BUG_ON(!subsys);
1311
1312 if (!type || !type->ct_group_ops ||
1313 (!type->ct_group_ops->make_group &&
1314 !type->ct_group_ops->make_item)) {
1315 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1316 goto out_put;
1317 }
1318
1319 /*
1320 * The subsystem may belong to a different module than the item
1321 * being created. We don't want to safely pin the new item but
1322 * fail to pin the subsystem it sits under.
1323 */
1324 if (!subsys->su_group.cg_item.ci_type) {
1325 ret = -EINVAL;
1326 goto out_put;
1327 }
1328 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1329 if (!try_module_get(subsys_owner)) {
1330 ret = -EINVAL;
1331 goto out_put;
1332 }
1333
1334 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1335 if (!name) {
1336 ret = -ENOMEM;
1337 goto out_subsys_put;
1338 }
1339
1340 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1341
1342 mutex_lock(&subsys->su_mutex);
1343 if (type->ct_group_ops->make_group) {
1344 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1345 if (!group)
1346 group = ERR_PTR(-ENOMEM);
1347 if (!IS_ERR(group)) {
1348 link_group(to_config_group(parent_item), group);
1349 item = &group->cg_item;
1350 } else
1351 ret = PTR_ERR(group);
1352 } else {
1353 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1354 if (!item)
1355 item = ERR_PTR(-ENOMEM);
1356 if (!IS_ERR(item))
1357 link_obj(parent_item, item);
1358 else
1359 ret = PTR_ERR(item);
1360 }
1361 mutex_unlock(&subsys->su_mutex);
1362
1363 kfree(name);
1364 if (ret) {
1365 /*
1366 * If ret != 0, then link_obj() was never called.
1367 * There are no extra references to clean up.
1368 */
1369 goto out_subsys_put;
1370 }
1371
1372 /*
1373 * link_obj() has been called (via link_group() for groups).
1374 * From here on out, errors must clean that up.
1375 */
1376
1377 type = item->ci_type;
1378 if (!type) {
1379 ret = -EINVAL;
1380 goto out_unlink;
1381 }
1382
1383 new_item_owner = type->ct_owner;
1384 if (!try_module_get(new_item_owner)) {
1385 ret = -EINVAL;
1386 goto out_unlink;
1387 }
1388
1389 /*
1390 * I hate doing it this way, but if there is
1391 * an error, module_put() probably should
1392 * happen after any cleanup.
1393 */
1394 module_got = 1;
1395
1396 /*
1397 * Make racing rmdir() fail if it did not tag parent with
1398 * CONFIGFS_USET_DROPPING
1399 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1400 * fail and let rmdir() terminate correctly
1401 */
1402 spin_lock(&configfs_dirent_lock);
1403 /* This will make configfs_detach_prep() fail */
1404 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1405 spin_unlock(&configfs_dirent_lock);
1406
1407 if (group)
1408 ret = configfs_attach_group(parent_item, item, dentry, frag);
1409 else
1410 ret = configfs_attach_item(parent_item, item, dentry, frag);
1411
1412 spin_lock(&configfs_dirent_lock);
1413 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1414 if (!ret)
1415 configfs_dir_set_ready(dentry->d_fsdata);
1416 spin_unlock(&configfs_dirent_lock);
1417
1418out_unlink:
1419 if (ret) {
1420 /* Tear down everything we built up */
1421 mutex_lock(&subsys->su_mutex);
1422
1423 client_disconnect_notify(parent_item, item);
1424 if (group)
1425 unlink_group(group);
1426 else
1427 unlink_obj(item);
1428 client_drop_item(parent_item, item);
1429
1430 mutex_unlock(&subsys->su_mutex);
1431
1432 if (module_got)
1433 module_put(new_item_owner);
1434 }
1435
1436out_subsys_put:
1437 if (ret)
1438 module_put(subsys_owner);
1439
1440out_put:
1441 /*
1442 * link_obj()/link_group() took a reference from child->parent,
1443 * so the parent is safely pinned. We can drop our working
1444 * reference.
1445 */
1446 config_item_put(parent_item);
1447 put_fragment(frag);
1448
1449out:
1450 return ret;
1451}
1452
1453static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1454{
1455 struct config_item *parent_item;
1456 struct config_item *item;
1457 struct configfs_subsystem *subsys;
1458 struct configfs_dirent *sd;
1459 struct configfs_fragment *frag;
1460 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1461 int ret;
1462
1463 sd = dentry->d_fsdata;
1464 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1465 return -EPERM;
1466
1467 /* Get a working ref until we have the child */
1468 parent_item = configfs_get_config_item(dentry->d_parent);
1469 subsys = to_config_group(parent_item)->cg_subsys;
1470 BUG_ON(!subsys);
1471
1472 if (!parent_item->ci_type) {
1473 config_item_put(parent_item);
1474 return -EINVAL;
1475 }
1476
1477 /* configfs_mkdir() shouldn't have allowed this */
1478 BUG_ON(!subsys->su_group.cg_item.ci_type);
1479 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1480
1481 /*
1482 * Ensure that no racing symlink() will make detach_prep() fail while
1483 * the new link is temporarily attached
1484 */
1485 do {
1486 struct dentry *wait;
1487
1488 mutex_lock(&configfs_symlink_mutex);
1489 spin_lock(&configfs_dirent_lock);
1490 /*
1491 * Here's where we check for dependents. We're protected by
1492 * configfs_dirent_lock.
1493 * If no dependent, atomically tag the item as dropping.
1494 */
1495 ret = sd->s_dependent_count ? -EBUSY : 0;
1496 if (!ret) {
1497 ret = configfs_detach_prep(dentry, &wait);
1498 if (ret)
1499 configfs_detach_rollback(dentry);
1500 }
1501 spin_unlock(&configfs_dirent_lock);
1502 mutex_unlock(&configfs_symlink_mutex);
1503
1504 if (ret) {
1505 if (ret != -EAGAIN) {
1506 config_item_put(parent_item);
1507 return ret;
1508 }
1509
1510 /* Wait until the racing operation terminates */
1511 inode_lock(d_inode(wait));
1512 inode_unlock(d_inode(wait));
1513 dput(wait);
1514 }
1515 } while (ret == -EAGAIN);
1516
1517 frag = sd->s_frag;
1518 if (down_write_killable(&frag->frag_sem)) {
1519 spin_lock(&configfs_dirent_lock);
1520 configfs_detach_rollback(dentry);
1521 spin_unlock(&configfs_dirent_lock);
1522 return -EINTR;
1523 }
1524 frag->frag_dead = true;
1525 up_write(&frag->frag_sem);
1526
1527 /* Get a working ref for the duration of this function */
1528 item = configfs_get_config_item(dentry);
1529
1530 /* Drop reference from above, item already holds one. */
1531 config_item_put(parent_item);
1532
1533 if (item->ci_type)
1534 dead_item_owner = item->ci_type->ct_owner;
1535
1536 if (sd->s_type & CONFIGFS_USET_DIR) {
1537 configfs_detach_group(item);
1538
1539 mutex_lock(&subsys->su_mutex);
1540 client_disconnect_notify(parent_item, item);
1541 unlink_group(to_config_group(item));
1542 } else {
1543 configfs_detach_item(item);
1544
1545 mutex_lock(&subsys->su_mutex);
1546 client_disconnect_notify(parent_item, item);
1547 unlink_obj(item);
1548 }
1549
1550 client_drop_item(parent_item, item);
1551 mutex_unlock(&subsys->su_mutex);
1552
1553 /* Drop our reference from above */
1554 config_item_put(item);
1555
1556 module_put(dead_item_owner);
1557 module_put(subsys_owner);
1558
1559 return 0;
1560}
1561
1562const struct inode_operations configfs_dir_inode_operations = {
1563 .mkdir = configfs_mkdir,
1564 .rmdir = configfs_rmdir,
1565 .symlink = configfs_symlink,
1566 .unlink = configfs_unlink,
1567 .lookup = configfs_lookup,
1568 .setattr = configfs_setattr,
1569};
1570
1571const struct inode_operations configfs_root_inode_operations = {
1572 .lookup = configfs_lookup,
1573 .setattr = configfs_setattr,
1574};
1575
1576static int configfs_dir_open(struct inode *inode, struct file *file)
1577{
1578 struct dentry * dentry = file->f_path.dentry;
1579 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1580 int err;
1581
1582 inode_lock(d_inode(dentry));
1583 /*
1584 * Fake invisibility if dir belongs to a group/default groups hierarchy
1585 * being attached
1586 */
1587 err = -ENOENT;
1588 if (configfs_dirent_is_ready(parent_sd)) {
1589 file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
1590 if (IS_ERR(file->private_data))
1591 err = PTR_ERR(file->private_data);
1592 else
1593 err = 0;
1594 }
1595 inode_unlock(d_inode(dentry));
1596
1597 return err;
1598}
1599
1600static int configfs_dir_close(struct inode *inode, struct file *file)
1601{
1602 struct dentry * dentry = file->f_path.dentry;
1603 struct configfs_dirent * cursor = file->private_data;
1604
1605 inode_lock(d_inode(dentry));
1606 spin_lock(&configfs_dirent_lock);
1607 list_del_init(&cursor->s_sibling);
1608 spin_unlock(&configfs_dirent_lock);
1609 inode_unlock(d_inode(dentry));
1610
1611 release_configfs_dirent(cursor);
1612
1613 return 0;
1614}
1615
1616/* Relationship between s_mode and the DT_xxx types */
1617static inline unsigned char dt_type(struct configfs_dirent *sd)
1618{
1619 return (sd->s_mode >> 12) & 15;
1620}
1621
1622static int configfs_readdir(struct file *file, struct dir_context *ctx)
1623{
1624 struct dentry *dentry = file->f_path.dentry;
1625 struct super_block *sb = dentry->d_sb;
1626 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1627 struct configfs_dirent *cursor = file->private_data;
1628 struct list_head *p, *q = &cursor->s_sibling;
1629 ino_t ino = 0;
1630
1631 if (!dir_emit_dots(file, ctx))
1632 return 0;
1633 spin_lock(&configfs_dirent_lock);
1634 if (ctx->pos == 2)
1635 list_move(q, &parent_sd->s_children);
1636 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1637 struct configfs_dirent *next;
1638 const char *name;
1639 int len;
1640 struct inode *inode = NULL;
1641
1642 next = list_entry(p, struct configfs_dirent, s_sibling);
1643 if (!next->s_element)
1644 continue;
1645
1646 /*
1647 * We'll have a dentry and an inode for
1648 * PINNED items and for open attribute
1649 * files. We lock here to prevent a race
1650 * with configfs_d_iput() clearing
1651 * s_dentry before calling iput().
1652 *
1653 * Why do we go to the trouble? If
1654 * someone has an attribute file open,
1655 * the inode number should match until
1656 * they close it. Beyond that, we don't
1657 * care.
1658 */
1659 dentry = next->s_dentry;
1660 if (dentry)
1661 inode = d_inode(dentry);
1662 if (inode)
1663 ino = inode->i_ino;
1664 spin_unlock(&configfs_dirent_lock);
1665 if (!inode)
1666 ino = iunique(sb, 2);
1667
1668 name = configfs_get_name(next);
1669 len = strlen(name);
1670
1671 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1672 return 0;
1673
1674 spin_lock(&configfs_dirent_lock);
1675 list_move(q, p);
1676 p = q;
1677 ctx->pos++;
1678 }
1679 spin_unlock(&configfs_dirent_lock);
1680 return 0;
1681}
1682
1683static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1684{
1685 struct dentry * dentry = file->f_path.dentry;
1686
1687 switch (whence) {
1688 case 1:
1689 offset += file->f_pos;
1690 /* fall through */
1691 case 0:
1692 if (offset >= 0)
1693 break;
1694 /* fall through */
1695 default:
1696 return -EINVAL;
1697 }
1698 if (offset != file->f_pos) {
1699 file->f_pos = offset;
1700 if (file->f_pos >= 2) {
1701 struct configfs_dirent *sd = dentry->d_fsdata;
1702 struct configfs_dirent *cursor = file->private_data;
1703 struct list_head *p;
1704 loff_t n = file->f_pos - 2;
1705
1706 spin_lock(&configfs_dirent_lock);
1707 list_del(&cursor->s_sibling);
1708 p = sd->s_children.next;
1709 while (n && p != &sd->s_children) {
1710 struct configfs_dirent *next;
1711 next = list_entry(p, struct configfs_dirent,
1712 s_sibling);
1713 if (next->s_element)
1714 n--;
1715 p = p->next;
1716 }
1717 list_add_tail(&cursor->s_sibling, p);
1718 spin_unlock(&configfs_dirent_lock);
1719 }
1720 }
1721 return offset;
1722}
1723
1724const struct file_operations configfs_dir_operations = {
1725 .open = configfs_dir_open,
1726 .release = configfs_dir_close,
1727 .llseek = configfs_dir_lseek,
1728 .read = generic_read_dir,
1729 .iterate_shared = configfs_readdir,
1730};
1731
1732/**
1733 * configfs_register_group - creates a parent-child relation between two groups
1734 * @parent_group: parent group
1735 * @group: child group
1736 *
1737 * link groups, creates dentry for the child and attaches it to the
1738 * parent dentry.
1739 *
1740 * Return: 0 on success, negative errno code on error
1741 */
1742int configfs_register_group(struct config_group *parent_group,
1743 struct config_group *group)
1744{
1745 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1746 struct dentry *parent;
1747 struct configfs_fragment *frag;
1748 int ret;
1749
1750 frag = new_fragment();
1751 if (!frag)
1752 return -ENOMEM;
1753
1754 mutex_lock(&subsys->su_mutex);
1755 link_group(parent_group, group);
1756 mutex_unlock(&subsys->su_mutex);
1757
1758 parent = parent_group->cg_item.ci_dentry;
1759
1760 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1761 ret = create_default_group(parent_group, group, frag);
1762 if (ret)
1763 goto err_out;
1764
1765 spin_lock(&configfs_dirent_lock);
1766 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1767 spin_unlock(&configfs_dirent_lock);
1768 inode_unlock(d_inode(parent));
1769 put_fragment(frag);
1770 return 0;
1771err_out:
1772 inode_unlock(d_inode(parent));
1773 mutex_lock(&subsys->su_mutex);
1774 unlink_group(group);
1775 mutex_unlock(&subsys->su_mutex);
1776 put_fragment(frag);
1777 return ret;
1778}
1779EXPORT_SYMBOL(configfs_register_group);
1780
1781/**
1782 * configfs_unregister_group() - unregisters a child group from its parent
1783 * @group: parent group to be unregistered
1784 *
1785 * Undoes configfs_register_group()
1786 */
1787void configfs_unregister_group(struct config_group *group)
1788{
1789 struct configfs_subsystem *subsys = group->cg_subsys;
1790 struct dentry *dentry = group->cg_item.ci_dentry;
1791 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1792 struct configfs_dirent *sd = dentry->d_fsdata;
1793 struct configfs_fragment *frag = sd->s_frag;
1794
1795 down_write(&frag->frag_sem);
1796 frag->frag_dead = true;
1797 up_write(&frag->frag_sem);
1798
1799 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1800 spin_lock(&configfs_dirent_lock);
1801 configfs_detach_prep(dentry, NULL);
1802 spin_unlock(&configfs_dirent_lock);
1803
1804 configfs_detach_group(&group->cg_item);
1805 d_inode(dentry)->i_flags |= S_DEAD;
1806 dont_mount(dentry);
1807 fsnotify_rmdir(d_inode(parent), dentry);
1808 d_delete(dentry);
1809 inode_unlock(d_inode(parent));
1810
1811 dput(dentry);
1812
1813 mutex_lock(&subsys->su_mutex);
1814 unlink_group(group);
1815 mutex_unlock(&subsys->su_mutex);
1816}
1817EXPORT_SYMBOL(configfs_unregister_group);
1818
1819/**
1820 * configfs_register_default_group() - allocates and registers a child group
1821 * @parent_group: parent group
1822 * @name: child group name
1823 * @item_type: child item type description
1824 *
1825 * boilerplate to allocate and register a child group with its parent. We need
1826 * kzalloc'ed memory because child's default_group is initially empty.
1827 *
1828 * Return: allocated config group or ERR_PTR() on error
1829 */
1830struct config_group *
1831configfs_register_default_group(struct config_group *parent_group,
1832 const char *name,
1833 const struct config_item_type *item_type)
1834{
1835 int ret;
1836 struct config_group *group;
1837
1838 group = kzalloc(sizeof(*group), GFP_KERNEL);
1839 if (!group)
1840 return ERR_PTR(-ENOMEM);
1841 config_group_init_type_name(group, name, item_type);
1842
1843 ret = configfs_register_group(parent_group, group);
1844 if (ret) {
1845 kfree(group);
1846 return ERR_PTR(ret);
1847 }
1848 return group;
1849}
1850EXPORT_SYMBOL(configfs_register_default_group);
1851
1852/**
1853 * configfs_unregister_default_group() - unregisters and frees a child group
1854 * @group: the group to act on
1855 */
1856void configfs_unregister_default_group(struct config_group *group)
1857{
1858 configfs_unregister_group(group);
1859 kfree(group);
1860}
1861EXPORT_SYMBOL(configfs_unregister_default_group);
1862
1863int configfs_register_subsystem(struct configfs_subsystem *subsys)
1864{
1865 int err;
1866 struct config_group *group = &subsys->su_group;
1867 struct dentry *dentry;
1868 struct dentry *root;
1869 struct configfs_dirent *sd;
1870 struct configfs_fragment *frag;
1871
1872 frag = new_fragment();
1873 if (!frag)
1874 return -ENOMEM;
1875
1876 root = configfs_pin_fs();
1877 if (IS_ERR(root)) {
1878 put_fragment(frag);
1879 return PTR_ERR(root);
1880 }
1881
1882 if (!group->cg_item.ci_name)
1883 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1884
1885 sd = root->d_fsdata;
1886 link_group(to_config_group(sd->s_element), group);
1887
1888 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1889
1890 err = -ENOMEM;
1891 dentry = d_alloc_name(root, group->cg_item.ci_name);
1892 if (dentry) {
1893 d_add(dentry, NULL);
1894
1895 err = configfs_attach_group(sd->s_element, &group->cg_item,
1896 dentry, frag);
1897 if (err) {
1898 BUG_ON(d_inode(dentry));
1899 d_drop(dentry);
1900 dput(dentry);
1901 } else {
1902 spin_lock(&configfs_dirent_lock);
1903 configfs_dir_set_ready(dentry->d_fsdata);
1904 spin_unlock(&configfs_dirent_lock);
1905 }
1906 }
1907
1908 inode_unlock(d_inode(root));
1909
1910 if (err) {
1911 unlink_group(group);
1912 configfs_release_fs();
1913 }
1914 put_fragment(frag);
1915
1916 return err;
1917}
1918
1919void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1920{
1921 struct config_group *group = &subsys->su_group;
1922 struct dentry *dentry = group->cg_item.ci_dentry;
1923 struct dentry *root = dentry->d_sb->s_root;
1924 struct configfs_dirent *sd = dentry->d_fsdata;
1925 struct configfs_fragment *frag = sd->s_frag;
1926
1927 if (dentry->d_parent != root) {
1928 pr_err("Tried to unregister non-subsystem!\n");
1929 return;
1930 }
1931
1932 down_write(&frag->frag_sem);
1933 frag->frag_dead = true;
1934 up_write(&frag->frag_sem);
1935
1936 inode_lock_nested(d_inode(root),
1937 I_MUTEX_PARENT);
1938 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1939 mutex_lock(&configfs_symlink_mutex);
1940 spin_lock(&configfs_dirent_lock);
1941 if (configfs_detach_prep(dentry, NULL)) {
1942 pr_err("Tried to unregister non-empty subsystem!\n");
1943 }
1944 spin_unlock(&configfs_dirent_lock);
1945 mutex_unlock(&configfs_symlink_mutex);
1946 configfs_detach_group(&group->cg_item);
1947 d_inode(dentry)->i_flags |= S_DEAD;
1948 dont_mount(dentry);
1949 fsnotify_rmdir(d_inode(root), dentry);
1950 inode_unlock(d_inode(dentry));
1951
1952 d_delete(dentry);
1953
1954 inode_unlock(d_inode(root));
1955
1956 dput(dentry);
1957
1958 unlink_group(group);
1959 configfs_release_fs();
1960}
1961
1962EXPORT_SYMBOL(configfs_register_subsystem);
1963EXPORT_SYMBOL(configfs_unregister_subsystem);