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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * dir.c - Operations for configfs directories.
4 *
5 * Based on sysfs:
6 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
7 *
8 * configfs Copyright (C) 2005 Oracle. All rights reserved.
9 */
10
11#undef DEBUG
12
13#include <linux/fs.h>
14#include <linux/fsnotify.h>
15#include <linux/mount.h>
16#include <linux/module.h>
17#include <linux/slab.h>
18#include <linux/err.h>
19
20#include <linux/configfs.h>
21#include "configfs_internal.h"
22
23/*
24 * Protects mutations of configfs_dirent linkage together with proper i_mutex
25 * Also protects mutations of symlinks linkage to target configfs_dirent
26 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
27 * and configfs_dirent_lock locked, in that order.
28 * This allows one to safely traverse configfs_dirent trees and symlinks without
29 * having to lock inodes.
30 *
31 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
32 * unlocked is not reliable unless in detach_groups() called from
33 * rmdir()/unregister() and from configfs_attach_group()
34 */
35DEFINE_SPINLOCK(configfs_dirent_lock);
36
37/*
38 * All of link_obj/unlink_obj/link_group/unlink_group require that
39 * subsys->su_mutex is held.
40 * But parent configfs_subsystem is NULL when config_item is root.
41 * Use this mutex when config_item is root.
42 */
43static DEFINE_MUTEX(configfs_subsystem_mutex);
44
45static void configfs_d_iput(struct dentry * dentry,
46 struct inode * inode)
47{
48 struct configfs_dirent *sd = dentry->d_fsdata;
49
50 if (sd) {
51 /* Coordinate with configfs_readdir */
52 spin_lock(&configfs_dirent_lock);
53 /*
54 * Set sd->s_dentry to null only when this dentry is the one
55 * that is going to be killed. Otherwise configfs_d_iput may
56 * run just after configfs_lookup and set sd->s_dentry to
57 * NULL even it's still in use.
58 */
59 if (sd->s_dentry == dentry)
60 sd->s_dentry = NULL;
61
62 spin_unlock(&configfs_dirent_lock);
63 configfs_put(sd);
64 }
65 iput(inode);
66}
67
68const struct dentry_operations configfs_dentry_ops = {
69 .d_iput = configfs_d_iput,
70};
71
72#ifdef CONFIG_LOCKDEP
73
74/*
75 * Helpers to make lockdep happy with our recursive locking of default groups'
76 * inodes (see configfs_attach_group() and configfs_detach_group()).
77 * We put default groups i_mutexes in separate classes according to their depth
78 * from the youngest non-default group ancestor.
79 *
80 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
81 * groups A/B and A/C will have their inode's mutex in class
82 * default_group_class[0], and default group A/C/D will be in
83 * default_group_class[1].
84 *
85 * The lock classes are declared and assigned in inode.c, according to the
86 * s_depth value.
87 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
88 * default groups, and reset to -1 when all default groups are attached. During
89 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
90 * inode's mutex is set to default_group_class[s_depth - 1].
91 */
92
93static void configfs_init_dirent_depth(struct configfs_dirent *sd)
94{
95 sd->s_depth = -1;
96}
97
98static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
99 struct configfs_dirent *sd)
100{
101 int parent_depth = parent_sd->s_depth;
102
103 if (parent_depth >= 0)
104 sd->s_depth = parent_depth + 1;
105}
106
107static void
108configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
109{
110 /*
111 * item's i_mutex class is already setup, so s_depth is now only
112 * used to set new sub-directories s_depth, which is always done
113 * with item's i_mutex locked.
114 */
115 /*
116 * sd->s_depth == -1 iff we are a non default group.
117 * else (we are a default group) sd->s_depth > 0 (see
118 * create_dir()).
119 */
120 if (sd->s_depth == -1)
121 /*
122 * We are a non default group and we are going to create
123 * default groups.
124 */
125 sd->s_depth = 0;
126}
127
128static void
129configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
130{
131 /* We will not create default groups anymore. */
132 sd->s_depth = -1;
133}
134
135#else /* CONFIG_LOCKDEP */
136
137static void configfs_init_dirent_depth(struct configfs_dirent *sd)
138{
139}
140
141static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
142 struct configfs_dirent *sd)
143{
144}
145
146static void
147configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
148{
149}
150
151static void
152configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
153{
154}
155
156#endif /* CONFIG_LOCKDEP */
157
158static struct configfs_fragment *new_fragment(void)
159{
160 struct configfs_fragment *p;
161
162 p = kmalloc_obj(struct configfs_fragment);
163 if (p) {
164 atomic_set(&p->frag_count, 1);
165 init_rwsem(&p->frag_sem);
166 p->frag_dead = false;
167 }
168 return p;
169}
170
171void put_fragment(struct configfs_fragment *frag)
172{
173 if (frag && atomic_dec_and_test(&frag->frag_count))
174 kfree(frag);
175}
176
177struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
178{
179 if (likely(frag))
180 atomic_inc(&frag->frag_count);
181 return frag;
182}
183
184/*
185 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
186 */
187static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
188 void *element, int type,
189 struct configfs_fragment *frag)
190{
191 struct configfs_dirent * sd;
192
193 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
194 if (!sd)
195 return ERR_PTR(-ENOMEM);
196
197 atomic_set(&sd->s_count, 1);
198 INIT_LIST_HEAD(&sd->s_children);
199 sd->s_element = element;
200 sd->s_type = type;
201 configfs_init_dirent_depth(sd);
202 spin_lock(&configfs_dirent_lock);
203 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
204 spin_unlock(&configfs_dirent_lock);
205 kmem_cache_free(configfs_dir_cachep, sd);
206 return ERR_PTR(-ENOENT);
207 }
208 sd->s_frag = get_fragment(frag);
209
210 /*
211 * configfs_lookup scans only for unpinned items. s_children is
212 * partitioned so that configfs_lookup can bail out early.
213 * CONFIGFS_PINNED and CONFIGFS_NOT_PINNED are not symmetrical. readdir
214 * cursors still need to be inserted at the front of the list.
215 */
216 if (sd->s_type & CONFIGFS_PINNED)
217 list_add_tail(&sd->s_sibling, &parent_sd->s_children);
218 else
219 list_add(&sd->s_sibling, &parent_sd->s_children);
220 spin_unlock(&configfs_dirent_lock);
221
222 return sd;
223}
224
225/*
226 *
227 * Return -EEXIST if there is already a configfs element with the same
228 * name for the same parent.
229 *
230 * called with parent inode's i_mutex held
231 */
232static int configfs_dirent_exists(struct dentry *dentry)
233{
234 struct configfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
235 const unsigned char *new = dentry->d_name.name;
236 struct configfs_dirent *sd;
237
238 spin_lock(&configfs_dirent_lock);
239 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
240 if (sd->s_element) {
241 if (strcmp(configfs_get_name(sd), new) == 0) {
242 spin_unlock(&configfs_dirent_lock);
243 return -EEXIST;
244 }
245 }
246 }
247 spin_unlock(&configfs_dirent_lock);
248
249 return 0;
250}
251
252
253int configfs_make_dirent(struct configfs_dirent * parent_sd,
254 struct dentry * dentry, void * element,
255 umode_t mode, int type, struct configfs_fragment *frag)
256{
257 struct configfs_dirent * sd;
258
259 sd = configfs_new_dirent(parent_sd, element, type, frag);
260 if (IS_ERR(sd))
261 return PTR_ERR(sd);
262
263 sd->s_mode = mode;
264 sd->s_dentry = dentry;
265 if (dentry)
266 dentry->d_fsdata = configfs_get(sd);
267
268 return 0;
269}
270
271static void configfs_remove_dirent(struct dentry *dentry)
272{
273 struct configfs_dirent *sd = dentry->d_fsdata;
274
275 if (!sd)
276 return;
277 spin_lock(&configfs_dirent_lock);
278 list_del_init(&sd->s_sibling);
279 spin_unlock(&configfs_dirent_lock);
280 configfs_put(sd);
281}
282
283/**
284 * configfs_create_dir - create a directory for an config_item.
285 * @item: config_itemwe're creating directory for.
286 * @dentry: config_item's dentry.
287 * @frag: config_item's fragment.
288 *
289 * Note: user-created entries won't be allowed under this new directory
290 * until it is validated by configfs_dir_set_ready()
291 */
292
293static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
294 struct configfs_fragment *frag)
295{
296 int error;
297 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
298 struct dentry *p = dentry->d_parent;
299 struct inode *p_inode = d_inode(p);
300 struct inode *inode;
301
302 BUG_ON(!item);
303
304 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
305 CONFIGFS_DIR | CONFIGFS_USET_CREATING,
306 frag);
307 if (unlikely(error))
308 return error;
309
310 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
311 inode = configfs_create(dentry, mode);
312 if (IS_ERR(inode))
313 goto out_remove;
314
315 inode->i_op = &configfs_dir_inode_operations;
316 inode->i_fop = &configfs_dir_operations;
317 /* directory inodes start off with i_nlink == 2 (for "." entry) */
318 inc_nlink(inode);
319 d_make_persistent(dentry, inode);
320 inc_nlink(p_inode);
321 inode_set_mtime_to_ts(p_inode, inode_set_ctime_current(p_inode));
322 item->ci_dentry = dentry;
323 return 0;
324
325out_remove:
326 configfs_put(dentry->d_fsdata);
327 configfs_remove_dirent(dentry);
328 return PTR_ERR(inode);
329}
330
331/*
332 * Allow userspace to create new entries under a new directory created with
333 * configfs_create_dir(), and under all of its chidlren directories recursively.
334 * @sd configfs_dirent of the new directory to validate
335 *
336 * Caller must hold configfs_dirent_lock.
337 */
338static void configfs_dir_set_ready(struct configfs_dirent *sd)
339{
340 struct configfs_dirent *child_sd;
341
342 sd->s_type &= ~CONFIGFS_USET_CREATING;
343 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
344 if (child_sd->s_type & CONFIGFS_USET_CREATING)
345 configfs_dir_set_ready(child_sd);
346}
347
348/*
349 * Check that a directory does not belong to a directory hierarchy being
350 * attached and not validated yet.
351 * @sd configfs_dirent of the directory to check
352 *
353 * @return non-zero iff the directory was validated
354 *
355 * Note: takes configfs_dirent_lock, so the result may change from false to true
356 * in two consecutive calls, but never from true to false.
357 */
358int configfs_dirent_is_ready(struct configfs_dirent *sd)
359{
360 int ret;
361
362 spin_lock(&configfs_dirent_lock);
363 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
364 spin_unlock(&configfs_dirent_lock);
365
366 return ret;
367}
368
369int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,
370 struct dentry *dentry, char *body)
371{
372 int err = 0;
373 umode_t mode = S_IFLNK | S_IRWXUGO;
374 struct configfs_dirent *p = parent->d_fsdata;
375 struct inode *p_inode = d_inode(parent);
376 struct inode *inode;
377
378 err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK,
379 p->s_frag);
380 if (err)
381 return err;
382
383 inode = configfs_create(dentry, mode);
384 if (IS_ERR(inode))
385 goto out_remove;
386
387 inode->i_link = body;
388 inode->i_op = &configfs_symlink_inode_operations;
389 d_make_persistent(dentry, inode);
390 inode_set_mtime_to_ts(p_inode, inode_set_ctime_current(p_inode));
391 return 0;
392
393out_remove:
394 configfs_put(dentry->d_fsdata);
395 configfs_remove_dirent(dentry);
396 return PTR_ERR(inode);
397}
398
399/**
400 * configfs_remove_dir - remove an config_item's directory.
401 * @d: dentry we're removing.
402 *
403 * The only thing special about this is that we remove any files in
404 * the directory before we remove the directory, and we've inlined
405 * what used to be configfs_rmdir() below, instead of calling separately.
406 *
407 * Caller holds the mutex of the item's inode
408 */
409
410static void configfs_remove_dir(struct dentry *d)
411{
412 struct dentry * parent = dget(d->d_parent);
413
414 configfs_remove_dirent(d);
415
416 if (d_really_is_positive(d)) {
417 if (unlikely(simple_rmdir(d_inode(parent), d)))
418 pr_warn("remove_dir (%pd): attributes remain", d);
419 else
420 /*
421 * configfs_get_config_item() takes a hashed dentry as
422 * proof that ->s_element is still alive. Our caller
423 * is about to drop the last reference to the item and
424 * the VFS will not unhash until after we return, so
425 * unhash it here.
426 */
427 d_drop(d);
428 }
429
430 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
431
432 dput(parent);
433}
434
435static struct dentry * configfs_lookup(struct inode *dir,
436 struct dentry *dentry,
437 unsigned int flags)
438{
439 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
440 struct configfs_dirent * sd;
441 struct inode *inode = NULL;
442
443 if (dentry->d_name.len > NAME_MAX)
444 return ERR_PTR(-ENAMETOOLONG);
445
446 /*
447 * Fake invisibility if dir belongs to a group/default groups hierarchy
448 * being attached
449 *
450 * This forbids userspace to read/write attributes of items which may
451 * not complete their initialization, since the dentries of the
452 * attributes won't be instantiated.
453 */
454 if (!configfs_dirent_is_ready(parent_sd))
455 return ERR_PTR(-ENOENT);
456
457 spin_lock(&configfs_dirent_lock);
458 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
459
460 /*
461 * s_children is partitioned, see configfs_new_dirent. The first
462 * pinned item indicates we can stop scanning.
463 */
464 if (sd->s_type & CONFIGFS_PINNED)
465 break;
466
467 /*
468 * Note: CONFIGFS_PINNED and CONFIGFS_NOT_PINNED are asymmetric.
469 * there may be a readdir cursor in this list
470 */
471 if ((sd->s_type & CONFIGFS_NOT_PINNED) &&
472 !strcmp(configfs_get_name(sd), dentry->d_name.name)) {
473 const struct configfs_attribute *attr = sd->s_element;
474 umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
475
476 dentry->d_fsdata = configfs_get(sd);
477 sd->s_dentry = dentry;
478 spin_unlock(&configfs_dirent_lock);
479
480 inode = configfs_create(dentry, mode);
481 if (IS_ERR(inode)) {
482 spin_lock(&configfs_dirent_lock);
483 sd->s_dentry = NULL;
484 spin_unlock(&configfs_dirent_lock);
485 configfs_put(sd);
486 return ERR_CAST(inode);
487 }
488 if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
489 inode->i_size = 0;
490 inode->i_fop = &configfs_bin_file_operations;
491 } else {
492 inode->i_size = PAGE_SIZE;
493 inode->i_fop = &configfs_file_operations;
494 }
495 goto done;
496 }
497 }
498 spin_unlock(&configfs_dirent_lock);
499done:
500 return d_splice_alias(inode, dentry);
501}
502
503/*
504 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
505 * attributes and are removed by rmdir(). We recurse, setting
506 * CONFIGFS_USET_DROPPING on all children that are candidates for
507 * default detach.
508 * If there is an error, the caller will reset the flags via
509 * configfs_detach_rollback().
510 */
511static int configfs_detach_prep(struct configfs_dirent *parent_sd, struct dentry **wait)
512{
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 (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)
532 *wait= dget(sd->s_dentry);
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, wait);
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 configfs_dirent *parent_sd)
558{
559 struct configfs_dirent *sd;
560
561 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
562
563 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
564 if (sd->s_type & CONFIGFS_USET_DEFAULT)
565 configfs_detach_rollback(sd);
566}
567
568/*
569 * Find the next non-cursor. configfs_dirent_lock held by caller.
570 */
571static struct configfs_dirent *next_dirent(struct configfs_dirent *parent,
572 struct configfs_dirent *last)
573{
574 struct configfs_dirent *s;
575
576 s = list_prepare_entry(last, &parent->s_children, s_sibling);
577
578 list_for_each_entry_continue(s, &parent->s_children, s_sibling) {
579 if (s->s_element)
580 return s;
581 }
582 return NULL;
583}
584
585static void detach_attrs(struct dentry *dentry)
586{
587 struct configfs_dirent *parent_sd;
588 struct configfs_dirent *sd, *next;
589
590 pr_debug("configfs %pd: dropping attrs for dir\n", dentry);
591
592 parent_sd = dentry->d_fsdata;
593
594 spin_lock(&configfs_dirent_lock);
595 for (sd = next_dirent(parent_sd, NULL); sd; sd = next) {
596 struct dentry *child;
597
598 next = next_dirent(parent_sd, sd);
599 if (!(sd->s_type & CONFIGFS_NOT_PINNED))
600 continue;
601 list_del_init(&sd->s_sibling);
602 child = sd->s_dentry;
603 if (child) {
604 spin_lock(&child->d_lock);
605 if (simple_positive(child)) {
606 dget_dlock(child);
607 __d_drop(child);
608 spin_unlock(&child->d_lock);
609 } else {
610 spin_unlock(&child->d_lock);
611 child = NULL;
612 }
613 }
614 spin_unlock(&configfs_dirent_lock);
615 if (child) {
616 struct inode *inode = child->d_inode;
617
618 inode_lock_nested(inode, I_MUTEX_NONDIR2);
619 inode_set_ctime_current(inode);
620 drop_nlink(inode);
621 inode_unlock(inode);
622 dput(child);
623 }
624 configfs_put(sd);
625 spin_lock(&configfs_dirent_lock);
626 }
627 spin_unlock(&configfs_dirent_lock);
628}
629
630static int populate_attrs(struct config_item *item)
631{
632 const struct config_item_type *t = item->ci_type;
633 const struct configfs_group_operations *ops;
634 const struct configfs_attribute *attr;
635 const struct configfs_bin_attribute *bin_attr;
636 int error = 0;
637 int i;
638
639 if (!t)
640 return -EINVAL;
641
642 ops = t->ct_group_ops;
643
644 if (t->ct_attrs_const) {
645 for (i = 0; (attr = t->ct_attrs_const[i]) != NULL; i++) {
646 if (ops && ops->is_visible && !ops->is_visible(item, attr, i))
647 continue;
648
649 error = configfs_create_file(item, attr);
650 if (error)
651 return error;
652 }
653 }
654 if (t->ct_bin_attrs) {
655 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
656 if (ops && ops->is_bin_visible && !ops->is_bin_visible(item, bin_attr, i))
657 continue;
658
659 error = configfs_create_bin_file(item, bin_attr);
660 if (error)
661 return error;
662 }
663 }
664
665 return 0;
666}
667
668static int configfs_attach_group(struct config_item *item,
669 struct dentry *dentry,
670 struct configfs_fragment *frag);
671static void configfs_detach_group(struct dentry *dentry);
672
673static void detach_groups(struct dentry *dentry)
674{
675 struct dentry *child;
676 struct configfs_dirent *parent_sd;
677 struct configfs_dirent *sd, *next;
678
679 parent_sd = dentry->d_fsdata;
680 spin_lock(&configfs_dirent_lock);
681 for (sd = next_dirent(parent_sd, NULL); sd; sd = next) {
682 next = next_dirent(parent_sd, sd);
683 if (!(sd->s_type & CONFIGFS_USET_DEFAULT))
684 continue;
685
686 child = dget(sd->s_dentry);
687 spin_unlock(&configfs_dirent_lock);
688
689 inode_lock(d_inode(child));
690
691 configfs_detach_group(child);
692 d_inode(child)->i_flags |= S_DEAD;
693 dont_mount(child);
694
695 inode_unlock(d_inode(child));
696
697 d_delete(child);
698 dput(child);
699 spin_lock(&configfs_dirent_lock);
700 }
701 spin_unlock(&configfs_dirent_lock);
702}
703
704/*
705 * This fakes mkdir(2) on a default_groups[] entry. It
706 * creates a dentry, attachs it, and then does fixup
707 * on the sd->s_type.
708 *
709 * We could, perhaps, tweak our parent's ->mkdir for a minute and
710 * try using vfs_mkdir. Just a thought.
711 */
712static int create_default_group(struct dentry *parent,
713 struct config_group *group,
714 struct configfs_fragment *frag)
715{
716 int ret;
717 struct configfs_dirent *sd;
718 /* We trust the caller holds a reference to parent */
719 struct dentry *child;
720
721 if (!group->cg_item.ci_name)
722 group->cg_item.ci_name = group->cg_item.ci_namebuf;
723
724 ret = -ENOMEM;
725 child = d_alloc_name(parent, group->cg_item.ci_name);
726 if (child) {
727 d_add(child, NULL);
728
729 ret = configfs_attach_group(&group->cg_item, child, frag);
730 if (!ret) {
731 sd = child->d_fsdata;
732 sd->s_type |= CONFIGFS_USET_DEFAULT;
733 } else {
734 BUG_ON(d_inode(child));
735 d_drop(child);
736 }
737 dput(child);
738 }
739
740 return ret;
741}
742
743static int populate_groups(struct config_group *group,
744 struct configfs_fragment *frag)
745{
746 struct dentry *parent = group->cg_item.ci_dentry;
747 struct config_group *new_group;
748
749 list_for_each_entry(new_group, &group->default_groups, group_entry) {
750 int ret = create_default_group(parent, new_group, frag);
751 if (ret)
752 return ret;
753 }
754 return 0;
755}
756
757void configfs_remove_default_groups(struct config_group *group)
758{
759 struct config_group *g, *n;
760
761 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
762 list_del(&g->group_entry);
763 config_item_put(&g->cg_item);
764 }
765}
766EXPORT_SYMBOL(configfs_remove_default_groups);
767
768/*
769 * All of link_obj/unlink_obj/link_group/unlink_group require that
770 * subsys->su_mutex is held.
771 */
772
773static void unlink_obj(struct config_item *item)
774{
775 struct config_group *group;
776
777 group = item->ci_group;
778 if (group) {
779 list_del_init(&item->ci_entry);
780
781 item->ci_group = NULL;
782 item->ci_parent = NULL;
783
784 /* Drop the reference for ci_entry */
785 config_item_put(item);
786
787 /* Drop the reference for ci_parent */
788 config_group_put(group);
789 }
790}
791
792static void link_obj(struct config_item *parent_item, struct config_item *item)
793{
794 /*
795 * Parent seems redundant with group, but it makes certain
796 * traversals much nicer.
797 */
798 item->ci_parent = parent_item;
799
800 /*
801 * We hold a reference on the parent for the child's ci_parent
802 * link.
803 */
804 item->ci_group = config_group_get(to_config_group(parent_item));
805 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
806
807 /*
808 * We hold a reference on the child for ci_entry on the parent's
809 * cg_children
810 */
811 config_item_get(item);
812}
813
814static void unlink_group(struct config_group *group)
815{
816 struct config_group *new_group;
817
818 list_for_each_entry(new_group, &group->default_groups, group_entry)
819 unlink_group(new_group);
820
821 group->cg_subsys = NULL;
822 unlink_obj(&group->cg_item);
823}
824
825static void link_group(struct config_group *parent_group, struct config_group *group)
826{
827 struct config_group *new_group;
828 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
829
830 link_obj(&parent_group->cg_item, &group->cg_item);
831
832 if (parent_group->cg_subsys)
833 subsys = parent_group->cg_subsys;
834 else if (configfs_is_root(&parent_group->cg_item))
835 subsys = to_configfs_subsystem(group);
836 else
837 BUG();
838 group->cg_subsys = subsys;
839
840 list_for_each_entry(new_group, &group->default_groups, group_entry)
841 link_group(group, new_group);
842}
843
844/* Caller holds the mutex of the item's inode */
845static void configfs_detach_item(struct dentry *dentry)
846{
847 detach_attrs(dentry);
848 configfs_remove_dir(dentry);
849}
850
851/*
852 * The goal is that configfs_attach_item() (and
853 * configfs_attach_group()) can be called from either the VFS or this
854 * module. That is, they assume that the items have been created,
855 * the dentry allocated, and the dcache is all ready to go.
856 *
857 * If they fail, they must clean up after themselves as if they
858 * had never been called. The caller (VFS or local function) will
859 * handle cleaning up the dcache bits.
860 *
861 * configfs_detach_group() and configfs_detach_item() behave similarly on
862 * the way out. They assume that the proper semaphores are held, they
863 * clean up the configfs items, and they expect their callers will
864 * handle the dcache bits.
865 */
866static int configfs_attach_item(struct config_item *item,
867 struct dentry *dentry,
868 struct configfs_fragment *frag)
869{
870 int ret;
871
872 ret = configfs_create_dir(item, dentry, frag);
873 if (!ret) {
874 ret = populate_attrs(item);
875 if (ret) {
876 /*
877 * We are going to remove an inode and its dentry but
878 * the VFS may already have hit and used them. Thus,
879 * we must lock them as rmdir() would.
880 */
881 inode_lock(d_inode(dentry));
882 configfs_detach_item(dentry);
883 d_inode(dentry)->i_flags |= S_DEAD;
884 dont_mount(dentry);
885 inode_unlock(d_inode(dentry));
886 d_delete(dentry);
887 }
888 }
889
890 return ret;
891}
892
893/* Caller holds the mutex of the group's inode */
894static void configfs_detach_group(struct dentry *dentry)
895{
896 detach_groups(dentry);
897 configfs_detach_item(dentry);
898}
899
900static int configfs_attach_group(struct config_item *item,
901 struct dentry *dentry,
902 struct configfs_fragment *frag)
903{
904 int ret;
905 struct configfs_dirent *sd;
906
907 ret = configfs_attach_item(item, dentry, frag);
908 if (!ret) {
909 sd = dentry->d_fsdata;
910 sd->s_type |= CONFIGFS_USET_DIR;
911
912 /*
913 * FYI, we're faking mkdir in populate_groups()
914 * We must lock the group's inode to avoid races with the VFS
915 * which can already hit the inode and try to add/remove entries
916 * under it.
917 *
918 * We must also lock the inode to remove it safely in case of
919 * error, as rmdir() would.
920 */
921 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
922 configfs_adjust_dir_dirent_depth_before_populate(sd);
923 ret = populate_groups(to_config_group(item), frag);
924 if (ret) {
925 configfs_detach_group(dentry);
926 d_inode(dentry)->i_flags |= S_DEAD;
927 dont_mount(dentry);
928 }
929 configfs_adjust_dir_dirent_depth_after_populate(sd);
930 inode_unlock(d_inode(dentry));
931 if (ret)
932 d_delete(dentry);
933 }
934
935 return ret;
936}
937
938/*
939 * After the item has been detached from the filesystem view, we are
940 * ready to tear it out of the hierarchy. Notify the client before
941 * we do that so they can perform any cleanup that requires
942 * navigating the hierarchy. A client does not need to provide this
943 * callback. The subsystem semaphore MUST be held by the caller, and
944 * references must be valid for both items. It also assumes the
945 * caller has validated ci_type.
946 */
947static void client_disconnect_notify(struct config_item *parent_item,
948 struct config_item *item)
949{
950 const struct config_item_type *type;
951
952 type = parent_item->ci_type;
953 BUG_ON(!type);
954
955 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
956 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
957 item);
958}
959
960/*
961 * Drop the initial reference from make_item()/make_group()
962 * This function assumes that reference is held on item
963 * and that item holds a valid reference to the parent. Also, it
964 * assumes the caller has validated ci_type.
965 */
966static void client_drop_item(struct config_item *parent_item,
967 struct config_item *item)
968{
969 const struct config_item_type *type;
970
971 type = parent_item->ci_type;
972 BUG_ON(!type);
973
974 /*
975 * If ->drop_item() exists, it is responsible for the
976 * config_item_put().
977 */
978 if (type->ct_group_ops && type->ct_group_ops->drop_item)
979 type->ct_group_ops->drop_item(to_config_group(parent_item),
980 item);
981 else
982 config_item_put(item);
983}
984
985#ifdef DEBUG
986static void configfs_dump_one(struct configfs_dirent *sd, int level)
987{
988 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
989
990#define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type)
991 type_print(CONFIGFS_ROOT);
992 type_print(CONFIGFS_DIR);
993 type_print(CONFIGFS_ITEM_ATTR);
994 type_print(CONFIGFS_ITEM_LINK);
995 type_print(CONFIGFS_USET_DIR);
996 type_print(CONFIGFS_USET_DEFAULT);
997 type_print(CONFIGFS_USET_DROPPING);
998#undef type_print
999}
1000
1001static int configfs_dump(struct configfs_dirent *sd, int level)
1002{
1003 struct configfs_dirent *child_sd;
1004 int ret = 0;
1005
1006 configfs_dump_one(sd, level);
1007
1008 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
1009 return 0;
1010
1011 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1012 ret = configfs_dump(child_sd, level + 2);
1013 if (ret)
1014 break;
1015 }
1016
1017 return ret;
1018}
1019#endif
1020
1021
1022/*
1023 * configfs_depend_item() and configfs_undepend_item()
1024 *
1025 * WARNING: Do not call these from a configfs callback!
1026 *
1027 * This describes these functions and their helpers.
1028 *
1029 * Allow another kernel system to depend on a config_item. If this
1030 * happens, the item cannot go away until the dependent can live without
1031 * it. The idea is to give client modules as simple an interface as
1032 * possible. When a system asks them to depend on an item, they just
1033 * call configfs_depend_item(). If the item is live and the client
1034 * driver is in good shape, we'll happily do the work for them.
1035 *
1036 * Why is the locking complex? Because configfs uses the VFS to handle
1037 * all locking, but this function is called outside the normal
1038 * VFS->configfs path. So it must take VFS locks to prevent the
1039 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1040 * why you can't call these functions underneath configfs callbacks.
1041 *
1042 * Note, btw, that this can be called at *any* time, even when a configfs
1043 * subsystem isn't registered, or when configfs is loading or unloading.
1044 * Just like configfs_register_subsystem(). So we take the same
1045 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1046 * If we can find the target item in the
1047 * configfs tree, it must be part of the subsystem tree as well, so we
1048 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1049 * locking out mkdir() and rmdir(), who might be racing us.
1050 */
1051
1052/*
1053 * configfs_depend_prep()
1054 *
1055 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1056 * attributes. This is similar but not the same to configfs_detach_prep().
1057 * Note that configfs_detach_prep() expects the parent to be locked when it
1058 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1059 * do that so we can unlock it if we find nothing.
1060 *
1061 * Here we do a depth-first search of the dentry hierarchy looking for
1062 * our object.
1063 * We deliberately ignore items tagged as dropping since they are virtually
1064 * dead, as well as items in the middle of attachment since they virtually
1065 * do not exist yet. This completes the locking out of racing mkdir() and
1066 * rmdir().
1067 * Note: subdirectories in the middle of attachment start with s_type =
1068 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1069 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1070 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1071 *
1072 * If the target is not found, -ENOENT is bubbled up.
1073 *
1074 * This adds a requirement that all config_items be unique!
1075 *
1076 * This is recursive. There isn't
1077 * much on the stack, though, so folks that need this function - be careful
1078 * about your stack! Patches will be accepted to make it iterative.
1079 */
1080static int configfs_depend_prep(struct configfs_dirent *sd,
1081 struct config_item *target)
1082{
1083 struct configfs_dirent *child_sd;
1084 int ret = 0;
1085
1086 if (sd->s_element == target) /* Boo-yah */
1087 goto out;
1088
1089 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1090 if ((child_sd->s_type & CONFIGFS_DIR) &&
1091 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1092 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1093 ret = configfs_depend_prep(child_sd, target);
1094 if (!ret)
1095 goto out; /* Child path boo-yah */
1096 }
1097 }
1098
1099 /* We looped all our children and didn't find target */
1100 ret = -ENOENT;
1101
1102out:
1103 return ret;
1104}
1105
1106static int configfs_do_depend_item(struct configfs_dirent *subsys_sd,
1107 struct config_item *target)
1108{
1109 struct configfs_dirent *p;
1110 int ret;
1111
1112 spin_lock(&configfs_dirent_lock);
1113 /* Scan the tree, return 0 if found */
1114 ret = configfs_depend_prep(subsys_sd, target);
1115 if (ret)
1116 goto out_unlock_dirent_lock;
1117
1118 /*
1119 * We are sure that the item is not about to be removed by rmdir(), and
1120 * not in the middle of attachment by mkdir().
1121 */
1122 p = target->ci_dentry->d_fsdata;
1123 p->s_dependent_count += 1;
1124
1125out_unlock_dirent_lock:
1126 spin_unlock(&configfs_dirent_lock);
1127
1128 return ret;
1129}
1130
1131static inline struct configfs_dirent *
1132configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1133 struct config_item *subsys_item)
1134{
1135 struct configfs_dirent *p;
1136 struct configfs_dirent *ret = NULL;
1137
1138 spin_lock(&configfs_dirent_lock);
1139 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1140 if (p->s_type & CONFIGFS_DIR &&
1141 p->s_element == subsys_item) {
1142 ret = p;
1143 break;
1144 }
1145 }
1146 spin_unlock(&configfs_dirent_lock);
1147
1148 return ret;
1149}
1150
1151
1152int configfs_depend_item(struct configfs_subsystem *subsys,
1153 struct config_item *target)
1154{
1155 int ret;
1156 struct configfs_dirent *subsys_sd;
1157 struct config_item *s_item = &subsys->su_group.cg_item;
1158 struct dentry *root;
1159
1160 /*
1161 * Pin the configfs filesystem. This means we can safely access
1162 * the root of the configfs filesystem.
1163 */
1164 root = configfs_pin_fs();
1165 if (IS_ERR(root))
1166 return PTR_ERR(root);
1167
1168 /*
1169 * Next, lock the root directory. We're going to check that the
1170 * subsystem is really registered, and so we need to lock out
1171 * configfs_[un]register_subsystem().
1172 */
1173 inode_lock(d_inode(root));
1174
1175 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1176 if (!subsys_sd) {
1177 ret = -ENOENT;
1178 goto out_unlock_fs;
1179 }
1180
1181 /* Ok, now we can trust subsys/s_item */
1182 ret = configfs_do_depend_item(subsys_sd, target);
1183
1184out_unlock_fs:
1185 inode_unlock(d_inode(root));
1186
1187 /*
1188 * If we succeeded, the fs is pinned via other methods. If not,
1189 * we're done with it anyway. So release_fs() is always right.
1190 */
1191 configfs_release_fs();
1192
1193 return ret;
1194}
1195EXPORT_SYMBOL(configfs_depend_item);
1196
1197/*
1198 * Release the dependent linkage. This is much simpler than
1199 * configfs_depend_item() because we know that the client driver is
1200 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1201 */
1202void configfs_undepend_item(struct config_item *target)
1203{
1204 struct configfs_dirent *sd;
1205
1206 /*
1207 * Since we can trust everything is pinned, we just need
1208 * configfs_dirent_lock.
1209 */
1210 spin_lock(&configfs_dirent_lock);
1211
1212 sd = target->ci_dentry->d_fsdata;
1213 BUG_ON(sd->s_dependent_count < 1);
1214
1215 sd->s_dependent_count -= 1;
1216
1217 /*
1218 * After this unlock, we cannot trust the item to stay alive!
1219 * DO NOT REFERENCE item after this unlock.
1220 */
1221 spin_unlock(&configfs_dirent_lock);
1222}
1223EXPORT_SYMBOL(configfs_undepend_item);
1224
1225/*
1226 * caller_subsys is a caller's subsystem not target's. This is used to
1227 * determine if we should lock root and check subsys or not. When we are
1228 * in the same subsystem as our target there is no need to do locking as
1229 * we know that subsys is valid and is not unregistered during this function
1230 * as we are called from callback of one of his children and VFS holds a lock
1231 * on some inode. Otherwise we have to lock our root to ensure that target's
1232 * subsystem it is not unregistered during this function.
1233 */
1234int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1235 struct config_item *target)
1236{
1237 struct configfs_subsystem *target_subsys;
1238 struct config_group *root, *parent;
1239 struct configfs_dirent *subsys_sd;
1240 int ret = -ENOENT;
1241
1242 /* Disallow this function for configfs root */
1243 if (configfs_is_root(target))
1244 return -EINVAL;
1245
1246 parent = target->ci_group;
1247 /*
1248 * This may happen when someone is trying to depend root
1249 * directory of some subsystem
1250 */
1251 if (configfs_is_root(&parent->cg_item)) {
1252 target_subsys = to_configfs_subsystem(to_config_group(target));
1253 root = parent;
1254 } else {
1255 target_subsys = parent->cg_subsys;
1256 /* Find a cofnigfs root as we may need it for locking */
1257 for (root = parent; !configfs_is_root(&root->cg_item);
1258 root = root->cg_item.ci_group)
1259 ;
1260 }
1261
1262 if (target_subsys != caller_subsys) {
1263 /*
1264 * We are in other configfs subsystem, so we have to do
1265 * additional locking to prevent other subsystem from being
1266 * unregistered
1267 */
1268 inode_lock(d_inode(root->cg_item.ci_dentry));
1269
1270 /*
1271 * As we are trying to depend item from other subsystem
1272 * we have to check if this subsystem is still registered
1273 */
1274 subsys_sd = configfs_find_subsys_dentry(
1275 root->cg_item.ci_dentry->d_fsdata,
1276 &target_subsys->su_group.cg_item);
1277 if (!subsys_sd)
1278 goto out_root_unlock;
1279 } else {
1280 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1281 }
1282
1283 /* Now we can execute core of depend item */
1284 ret = configfs_do_depend_item(subsys_sd, target);
1285
1286 if (target_subsys != caller_subsys)
1287out_root_unlock:
1288 /*
1289 * We were called from subsystem other than our target so we
1290 * took some locks so now it's time to release them
1291 */
1292 inode_unlock(d_inode(root->cg_item.ci_dentry));
1293
1294 return ret;
1295}
1296EXPORT_SYMBOL(configfs_depend_item_unlocked);
1297
1298static struct dentry *configfs_mkdir(const struct mnt_idmap *idmap, struct inode *dir,
1299 struct dentry *dentry, umode_t mode)
1300{
1301 int ret = 0;
1302 int module_got = 0;
1303 struct config_group *group = NULL;
1304 struct config_item *item = NULL;
1305 struct config_item *parent_item;
1306 struct configfs_subsystem *subsys;
1307 struct configfs_dirent *sd;
1308 const struct config_item_type *type;
1309 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1310 struct configfs_fragment *frag;
1311 struct name_snapshot n;
1312 const char *name;
1313
1314 take_dentry_name_snapshot(&n, dentry);
1315 name = n.name.name;
1316
1317 sd = dentry->d_parent->d_fsdata;
1318
1319 /*
1320 * Fake invisibility if dir belongs to a group/default groups hierarchy
1321 * being attached
1322 */
1323 if (!configfs_dirent_is_ready(sd)) {
1324 ret = -ENOENT;
1325 goto out;
1326 }
1327
1328 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1329 ret = -EPERM;
1330 goto out;
1331 }
1332
1333 frag = new_fragment();
1334 if (!frag) {
1335 ret = -ENOMEM;
1336 goto out;
1337 }
1338
1339 /* Get a working ref for the duration of this function */
1340 parent_item = configfs_get_config_item(dentry->d_parent);
1341 type = parent_item->ci_type;
1342 subsys = to_config_group(parent_item)->cg_subsys;
1343 BUG_ON(!subsys);
1344
1345 if (!type || !type->ct_group_ops ||
1346 (!type->ct_group_ops->make_group &&
1347 !type->ct_group_ops->make_item)) {
1348 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1349 goto out_put;
1350 }
1351
1352 /*
1353 * The subsystem may belong to a different module than the item
1354 * being created. We don't want to safely pin the new item but
1355 * fail to pin the subsystem it sits under.
1356 */
1357 if (!subsys->su_group.cg_item.ci_type) {
1358 ret = -EINVAL;
1359 goto out_put;
1360 }
1361 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1362 if (!try_module_get(subsys_owner)) {
1363 ret = -EINVAL;
1364 goto out_put;
1365 }
1366
1367 mutex_lock(&subsys->su_mutex);
1368 if (type->ct_group_ops->make_group) {
1369 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1370 if (!group)
1371 group = ERR_PTR(-ENOMEM);
1372 if (!IS_ERR(group)) {
1373 link_group(to_config_group(parent_item), group);
1374 item = &group->cg_item;
1375 } else
1376 ret = PTR_ERR(group);
1377 } else {
1378 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1379 if (!item)
1380 item = ERR_PTR(-ENOMEM);
1381 if (!IS_ERR(item))
1382 link_obj(parent_item, item);
1383 else
1384 ret = PTR_ERR(item);
1385 }
1386 mutex_unlock(&subsys->su_mutex);
1387
1388 if (ret) {
1389 /*
1390 * If ret != 0, then link_obj() was never called.
1391 * There are no extra references to clean up.
1392 */
1393 goto out_subsys_put;
1394 }
1395
1396 /*
1397 * link_obj() has been called (via link_group() for groups).
1398 * From here on out, errors must clean that up.
1399 */
1400
1401 type = item->ci_type;
1402 if (!type) {
1403 ret = -EINVAL;
1404 goto out_unlink;
1405 }
1406
1407 new_item_owner = type->ct_owner;
1408 if (!try_module_get(new_item_owner)) {
1409 ret = -EINVAL;
1410 goto out_unlink;
1411 }
1412
1413 /*
1414 * I hate doing it this way, but if there is
1415 * an error, module_put() probably should
1416 * happen after any cleanup.
1417 */
1418 module_got = 1;
1419
1420 /*
1421 * Make racing rmdir() fail if it did not tag parent with
1422 * CONFIGFS_USET_DROPPING
1423 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1424 * fail and let rmdir() terminate correctly
1425 */
1426 spin_lock(&configfs_dirent_lock);
1427 /* This will make configfs_detach_prep() fail */
1428 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1429 spin_unlock(&configfs_dirent_lock);
1430
1431 if (group)
1432 ret = configfs_attach_group(item, dentry, frag);
1433 else
1434 ret = configfs_attach_item(item, dentry, frag);
1435
1436 spin_lock(&configfs_dirent_lock);
1437 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1438 if (!ret)
1439 configfs_dir_set_ready(dentry->d_fsdata);
1440 spin_unlock(&configfs_dirent_lock);
1441
1442out_unlink:
1443 if (ret) {
1444 /* Tear down everything we built up */
1445 mutex_lock(&subsys->su_mutex);
1446
1447 client_disconnect_notify(parent_item, item);
1448 if (group)
1449 unlink_group(group);
1450 else
1451 unlink_obj(item);
1452 client_drop_item(parent_item, item);
1453
1454 mutex_unlock(&subsys->su_mutex);
1455
1456 if (module_got)
1457 module_put(new_item_owner);
1458 }
1459
1460out_subsys_put:
1461 if (ret)
1462 module_put(subsys_owner);
1463
1464out_put:
1465 /*
1466 * link_obj()/link_group() took a reference from child->parent,
1467 * so the parent is safely pinned. We can drop our working
1468 * reference.
1469 */
1470 config_item_put(parent_item);
1471 put_fragment(frag);
1472
1473out:
1474 release_dentry_name_snapshot(&n);
1475 return ERR_PTR(ret);
1476}
1477
1478static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1479{
1480 struct config_item *parent_item;
1481 struct config_item *item;
1482 struct configfs_subsystem *subsys;
1483 struct configfs_dirent *sd;
1484 struct configfs_fragment *frag;
1485 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1486 int ret;
1487
1488 sd = dentry->d_fsdata;
1489 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1490 return -EPERM;
1491
1492 /* Get a working ref until we have the child */
1493 parent_item = configfs_get_config_item(dentry->d_parent);
1494 subsys = to_config_group(parent_item)->cg_subsys;
1495 BUG_ON(!subsys);
1496
1497 if (!parent_item->ci_type) {
1498 config_item_put(parent_item);
1499 return -EINVAL;
1500 }
1501
1502 /* configfs_mkdir() shouldn't have allowed this */
1503 BUG_ON(!subsys->su_group.cg_item.ci_type);
1504 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1505
1506 /*
1507 * Ensure that no racing symlink() will make detach_prep() fail while
1508 * the new link is temporarily attached
1509 */
1510 do {
1511 struct dentry *wait;
1512
1513 mutex_lock(&configfs_symlink_mutex);
1514 spin_lock(&configfs_dirent_lock);
1515 /*
1516 * Here's where we check for dependents. We're protected by
1517 * configfs_dirent_lock.
1518 * If no dependent, atomically tag the item as dropping.
1519 */
1520 ret = sd->s_dependent_count ? -EBUSY : 0;
1521 if (!ret) {
1522 ret = configfs_detach_prep(sd, &wait);
1523 if (ret)
1524 configfs_detach_rollback(sd);
1525 }
1526 spin_unlock(&configfs_dirent_lock);
1527 mutex_unlock(&configfs_symlink_mutex);
1528
1529 if (ret) {
1530 if (ret != -EAGAIN) {
1531 config_item_put(parent_item);
1532 return ret;
1533 }
1534
1535 /* Wait until the racing operation terminates */
1536 inode_lock(d_inode(wait));
1537 inode_unlock(d_inode(wait));
1538 dput(wait);
1539 }
1540 } while (ret == -EAGAIN);
1541
1542 frag = sd->s_frag;
1543 if (down_write_killable(&frag->frag_sem)) {
1544 spin_lock(&configfs_dirent_lock);
1545 configfs_detach_rollback(sd);
1546 spin_unlock(&configfs_dirent_lock);
1547 config_item_put(parent_item);
1548 return -EINTR;
1549 }
1550 frag->frag_dead = true;
1551 up_write(&frag->frag_sem);
1552
1553 /* Get a working ref for the duration of this function */
1554 item = configfs_get_config_item(dentry);
1555
1556 /* Drop reference from above, item already holds one. */
1557 config_item_put(parent_item);
1558
1559 if (item->ci_type)
1560 dead_item_owner = item->ci_type->ct_owner;
1561
1562 if (sd->s_type & CONFIGFS_USET_DIR) {
1563 configfs_detach_group(dentry);
1564
1565 mutex_lock(&subsys->su_mutex);
1566 client_disconnect_notify(parent_item, item);
1567 unlink_group(to_config_group(item));
1568 } else {
1569 configfs_detach_item(dentry);
1570
1571 mutex_lock(&subsys->su_mutex);
1572 client_disconnect_notify(parent_item, item);
1573 unlink_obj(item);
1574 }
1575
1576 client_drop_item(parent_item, item);
1577 mutex_unlock(&subsys->su_mutex);
1578
1579 /* Drop our reference from above */
1580 config_item_put(item);
1581
1582 module_put(dead_item_owner);
1583 module_put(subsys_owner);
1584
1585 return 0;
1586}
1587
1588const struct inode_operations configfs_dir_inode_operations = {
1589 .mkdir = configfs_mkdir,
1590 .rmdir = configfs_rmdir,
1591 .symlink = configfs_symlink,
1592 .unlink = configfs_unlink,
1593 .lookup = configfs_lookup,
1594 .setattr = configfs_setattr,
1595};
1596
1597const struct inode_operations configfs_root_inode_operations = {
1598 .lookup = configfs_lookup,
1599 .setattr = configfs_setattr,
1600};
1601
1602static int configfs_dir_open(struct inode *inode, struct file *file)
1603{
1604 struct dentry * dentry = file->f_path.dentry;
1605 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1606 int err;
1607
1608 inode_lock(d_inode(dentry));
1609 /*
1610 * Fake invisibility if dir belongs to a group/default groups hierarchy
1611 * being attached
1612 */
1613 err = -ENOENT;
1614 if (configfs_dirent_is_ready(parent_sd)) {
1615 file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
1616 err = PTR_ERR_OR_ZERO(file->private_data);
1617 }
1618 inode_unlock(d_inode(dentry));
1619
1620 return err;
1621}
1622
1623static int configfs_dir_close(struct inode *inode, struct file *file)
1624{
1625 struct dentry * dentry = file->f_path.dentry;
1626 struct configfs_dirent * cursor = file->private_data;
1627
1628 inode_lock(d_inode(dentry));
1629 spin_lock(&configfs_dirent_lock);
1630 list_del_init(&cursor->s_sibling);
1631 spin_unlock(&configfs_dirent_lock);
1632 inode_unlock(d_inode(dentry));
1633
1634 release_configfs_dirent(cursor);
1635
1636 return 0;
1637}
1638
1639static int configfs_readdir(struct file *file, struct dir_context *ctx)
1640{
1641 struct dentry *dentry = file->f_path.dentry;
1642 struct super_block *sb = dentry->d_sb;
1643 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1644 struct configfs_dirent *cursor = file->private_data;
1645 struct list_head *p, *q = &cursor->s_sibling;
1646 ino_t ino = 0;
1647
1648 if (!dir_emit_dots(file, ctx))
1649 return 0;
1650 spin_lock(&configfs_dirent_lock);
1651 if (ctx->pos == 2)
1652 list_move(q, &parent_sd->s_children);
1653 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1654 struct configfs_dirent *next;
1655 const char *name;
1656 int len;
1657 struct inode *inode = NULL;
1658
1659 next = list_entry(p, struct configfs_dirent, s_sibling);
1660 if (!next->s_element)
1661 continue;
1662
1663 /*
1664 * We'll have a dentry and an inode for
1665 * PINNED items and for open attribute
1666 * files. We lock here to prevent a race
1667 * with configfs_d_iput() clearing
1668 * s_dentry before calling iput().
1669 *
1670 * Why do we go to the trouble? If
1671 * someone has an attribute file open,
1672 * the inode number should match until
1673 * they close it. Beyond that, we don't
1674 * care.
1675 */
1676 dentry = next->s_dentry;
1677 if (dentry)
1678 inode = d_inode(dentry);
1679 if (inode)
1680 ino = inode->i_ino;
1681 spin_unlock(&configfs_dirent_lock);
1682 if (!inode)
1683 ino = iunique(sb, 2);
1684
1685 name = configfs_get_name(next);
1686 len = strlen(name);
1687
1688 if (!dir_emit(ctx, name, len, ino,
1689 fs_umode_to_dtype(next->s_mode)))
1690 return 0;
1691
1692 spin_lock(&configfs_dirent_lock);
1693 list_move(q, p);
1694 p = q;
1695 ctx->pos++;
1696 }
1697 spin_unlock(&configfs_dirent_lock);
1698 return 0;
1699}
1700
1701static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1702{
1703 struct dentry * dentry = file->f_path.dentry;
1704
1705 switch (whence) {
1706 case 1:
1707 offset += file->f_pos;
1708 fallthrough;
1709 case 0:
1710 if (offset >= 0)
1711 break;
1712 fallthrough;
1713 default:
1714 return -EINVAL;
1715 }
1716 if (offset != file->f_pos) {
1717 file->f_pos = offset;
1718 if (file->f_pos >= 2) {
1719 struct configfs_dirent *sd = dentry->d_fsdata;
1720 struct configfs_dirent *cursor = file->private_data;
1721 struct list_head *p;
1722 loff_t n = file->f_pos - 2;
1723
1724 spin_lock(&configfs_dirent_lock);
1725 list_del(&cursor->s_sibling);
1726 p = sd->s_children.next;
1727 while (n && p != &sd->s_children) {
1728 struct configfs_dirent *next;
1729 next = list_entry(p, struct configfs_dirent,
1730 s_sibling);
1731 if (next->s_element)
1732 n--;
1733 p = p->next;
1734 }
1735 list_add_tail(&cursor->s_sibling, p);
1736 spin_unlock(&configfs_dirent_lock);
1737 }
1738 }
1739 return offset;
1740}
1741
1742const struct file_operations configfs_dir_operations = {
1743 .open = configfs_dir_open,
1744 .release = configfs_dir_close,
1745 .llseek = configfs_dir_lseek,
1746 .read = generic_read_dir,
1747 .iterate_shared = configfs_readdir,
1748};
1749
1750/**
1751 * configfs_register_group - creates a parent-child relation between two groups
1752 * @parent_group: parent group
1753 * @group: child group
1754 *
1755 * link groups, creates dentry for the child and attaches it to the
1756 * parent dentry.
1757 *
1758 * Return: 0 on success, negative errno code on error
1759 */
1760int configfs_register_group(struct config_group *parent_group,
1761 struct config_group *group)
1762{
1763 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1764 struct dentry *parent;
1765 struct configfs_fragment *frag;
1766 int ret;
1767
1768 frag = new_fragment();
1769 if (!frag)
1770 return -ENOMEM;
1771
1772 mutex_lock(&subsys->su_mutex);
1773 link_group(parent_group, group);
1774 mutex_unlock(&subsys->su_mutex);
1775
1776 parent = parent_group->cg_item.ci_dentry;
1777
1778 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1779 ret = create_default_group(parent, group, frag);
1780 if (ret)
1781 goto err_out;
1782
1783 spin_lock(&configfs_dirent_lock);
1784 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1785 spin_unlock(&configfs_dirent_lock);
1786 inode_unlock(d_inode(parent));
1787 put_fragment(frag);
1788 return 0;
1789err_out:
1790 inode_unlock(d_inode(parent));
1791 mutex_lock(&subsys->su_mutex);
1792 unlink_group(group);
1793 mutex_unlock(&subsys->su_mutex);
1794 put_fragment(frag);
1795 return ret;
1796}
1797EXPORT_SYMBOL(configfs_register_group);
1798
1799/**
1800 * configfs_unregister_group() - unregisters a child group from its parent
1801 * @group: parent group to be unregistered
1802 *
1803 * Undoes configfs_register_group()
1804 */
1805void configfs_unregister_group(struct config_group *group)
1806{
1807 struct configfs_subsystem *subsys = group->cg_subsys;
1808 struct dentry *dentry = dget(group->cg_item.ci_dentry);
1809 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1810 struct configfs_dirent *sd = dentry->d_fsdata;
1811 struct configfs_fragment *frag = sd->s_frag;
1812
1813 down_write(&frag->frag_sem);
1814 frag->frag_dead = true;
1815 up_write(&frag->frag_sem);
1816
1817 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1818 spin_lock(&configfs_dirent_lock);
1819 configfs_detach_prep(sd, NULL);
1820 spin_unlock(&configfs_dirent_lock);
1821
1822 configfs_detach_group(dentry);
1823 d_inode(dentry)->i_flags |= S_DEAD;
1824 dont_mount(dentry);
1825 d_drop(dentry);
1826 fsnotify_rmdir(d_inode(parent), dentry);
1827 inode_unlock(d_inode(parent));
1828
1829 dput(dentry);
1830
1831 mutex_lock(&subsys->su_mutex);
1832 unlink_group(group);
1833 mutex_unlock(&subsys->su_mutex);
1834}
1835EXPORT_SYMBOL(configfs_unregister_group);
1836
1837/**
1838 * configfs_register_default_group() - allocates and registers a child group
1839 * @parent_group: parent group
1840 * @name: child group name
1841 * @item_type: child item type description
1842 *
1843 * boilerplate to allocate and register a child group with its parent. We need
1844 * kzalloc'ed memory because child's default_group is initially empty.
1845 *
1846 * Return: allocated config group or ERR_PTR() on error
1847 */
1848struct config_group *
1849configfs_register_default_group(struct config_group *parent_group,
1850 const char *name,
1851 const struct config_item_type *item_type)
1852{
1853 int ret;
1854 struct config_group *group;
1855
1856 group = kzalloc_obj(*group);
1857 if (!group)
1858 return ERR_PTR(-ENOMEM);
1859 config_group_init_type_name(group, name, item_type);
1860
1861 ret = configfs_register_group(parent_group, group);
1862 if (ret) {
1863 kfree(group);
1864 return ERR_PTR(ret);
1865 }
1866 return group;
1867}
1868EXPORT_SYMBOL(configfs_register_default_group);
1869
1870/**
1871 * configfs_unregister_default_group() - unregisters and frees a child group
1872 * @group: the group to act on
1873 */
1874void configfs_unregister_default_group(struct config_group *group)
1875{
1876 configfs_unregister_group(group);
1877 kfree(group);
1878}
1879EXPORT_SYMBOL(configfs_unregister_default_group);
1880
1881int configfs_register_subsystem(struct configfs_subsystem *subsys)
1882{
1883 int err;
1884 struct config_group *group = &subsys->su_group;
1885 struct dentry *dentry;
1886 struct dentry *root;
1887 struct configfs_dirent *sd;
1888 struct configfs_fragment *frag;
1889
1890 frag = new_fragment();
1891 if (!frag)
1892 return -ENOMEM;
1893
1894 root = configfs_pin_fs();
1895 if (IS_ERR(root)) {
1896 put_fragment(frag);
1897 return PTR_ERR(root);
1898 }
1899
1900 if (!group->cg_item.ci_name)
1901 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1902
1903 sd = root->d_fsdata;
1904 mutex_lock(&configfs_subsystem_mutex);
1905 link_group(to_config_group(sd->s_element), group);
1906 mutex_unlock(&configfs_subsystem_mutex);
1907
1908 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1909
1910 err = -ENOMEM;
1911 dentry = d_alloc_name(root, group->cg_item.ci_name);
1912 if (dentry) {
1913 d_add(dentry, NULL);
1914
1915 err = configfs_dirent_exists(dentry);
1916 if (!err)
1917 err = configfs_attach_group(&group->cg_item,
1918 dentry, frag);
1919 if (err) {
1920 BUG_ON(d_inode(dentry));
1921 d_drop(dentry);
1922 } else {
1923 spin_lock(&configfs_dirent_lock);
1924 configfs_dir_set_ready(dentry->d_fsdata);
1925 spin_unlock(&configfs_dirent_lock);
1926 }
1927 dput(dentry);
1928 }
1929
1930 inode_unlock(d_inode(root));
1931
1932 if (err) {
1933 mutex_lock(&configfs_subsystem_mutex);
1934 unlink_group(group);
1935 mutex_unlock(&configfs_subsystem_mutex);
1936 configfs_release_fs();
1937 }
1938 put_fragment(frag);
1939
1940 return err;
1941}
1942
1943void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1944{
1945 struct config_group *group = &subsys->su_group;
1946 struct dentry *dentry = dget(group->cg_item.ci_dentry);
1947 struct dentry *root = dentry->d_sb->s_root;
1948 struct configfs_dirent *sd = dentry->d_fsdata;
1949 struct configfs_fragment *frag = sd->s_frag;
1950
1951 if (dentry->d_parent != root) {
1952 pr_err("Tried to unregister non-subsystem!\n");
1953 return;
1954 }
1955
1956 down_write(&frag->frag_sem);
1957 frag->frag_dead = true;
1958 up_write(&frag->frag_sem);
1959
1960 inode_lock_nested(d_inode(root),
1961 I_MUTEX_PARENT);
1962 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1963 mutex_lock(&configfs_symlink_mutex);
1964 spin_lock(&configfs_dirent_lock);
1965 if (configfs_detach_prep(sd, NULL)) {
1966 pr_err("Tried to unregister non-empty subsystem!\n");
1967 }
1968 spin_unlock(&configfs_dirent_lock);
1969 mutex_unlock(&configfs_symlink_mutex);
1970 configfs_detach_group(dentry);
1971 d_inode(dentry)->i_flags |= S_DEAD;
1972 dont_mount(dentry);
1973 inode_unlock(d_inode(dentry));
1974
1975 d_drop(dentry);
1976 fsnotify_rmdir(d_inode(root), dentry);
1977
1978 inode_unlock(d_inode(root));
1979
1980 dput(dentry);
1981
1982 mutex_lock(&configfs_subsystem_mutex);
1983 unlink_group(group);
1984 mutex_unlock(&configfs_subsystem_mutex);
1985 configfs_release_fs();
1986}
1987
1988EXPORT_SYMBOL(configfs_register_subsystem);
1989EXPORT_SYMBOL(configfs_unregister_subsystem);