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