xref: /linux/fs/notify/fsnotify.c (revision e04e2b760ddbe3d7b283a05898c3a029085cd8cd)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
4  */
5 
6 #include <linux/dcache.h>
7 #include <linux/fs.h>
8 #include <linux/gfp.h>
9 #include <linux/init.h>
10 #include <linux/module.h>
11 #include <linux/mount.h>
12 #include <linux/srcu.h>
13 
14 #include <linux/fsnotify_backend.h>
15 #include "fsnotify.h"
16 
17 /*
18  * Clear all of the marks on an inode when it is being evicted from core
19  */
20 void __fsnotify_inode_delete(struct inode *inode)
21 {
22 	fsnotify_clear_marks_by_inode(inode);
23 }
24 EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
25 
26 void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
27 {
28 	fsnotify_clear_marks_by_mount(mnt);
29 }
30 
31 /**
32  * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
33  * @sb: superblock being unmounted.
34  *
35  * Called during unmount with no locks held, so needs to be safe against
36  * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
37  */
38 static void fsnotify_unmount_inodes(struct super_block *sb)
39 {
40 	struct inode *inode, *iput_inode = NULL;
41 
42 	spin_lock(&sb->s_inode_list_lock);
43 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
44 		/*
45 		 * We cannot __iget() an inode in state I_FREEING,
46 		 * I_WILL_FREE, or I_NEW which is fine because by that point
47 		 * the inode cannot have any associated watches.
48 		 */
49 		spin_lock(&inode->i_lock);
50 		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
51 			spin_unlock(&inode->i_lock);
52 			continue;
53 		}
54 
55 		/*
56 		 * If i_count is zero, the inode cannot have any watches and
57 		 * doing an __iget/iput with SB_ACTIVE clear would actually
58 		 * evict all inodes with zero i_count from icache which is
59 		 * unnecessarily violent and may in fact be illegal to do.
60 		 * However, we should have been called /after/ evict_inodes
61 		 * removed all zero refcount inodes, in any case.  Test to
62 		 * be sure.
63 		 */
64 		if (!atomic_read(&inode->i_count)) {
65 			spin_unlock(&inode->i_lock);
66 			continue;
67 		}
68 
69 		__iget(inode);
70 		spin_unlock(&inode->i_lock);
71 		spin_unlock(&sb->s_inode_list_lock);
72 
73 		iput(iput_inode);
74 
75 		/* for each watch, send FS_UNMOUNT and then remove it */
76 		fsnotify_inode(inode, FS_UNMOUNT);
77 
78 		fsnotify_inode_delete(inode);
79 
80 		iput_inode = inode;
81 
82 		cond_resched();
83 		spin_lock(&sb->s_inode_list_lock);
84 	}
85 	spin_unlock(&sb->s_inode_list_lock);
86 
87 	iput(iput_inode);
88 }
89 
90 void fsnotify_sb_delete(struct super_block *sb)
91 {
92 	struct fsnotify_sb_info *sbinfo = fsnotify_sb_info(sb);
93 
94 	/* Were any marks ever added to any object on this sb? */
95 	if (!sbinfo)
96 		return;
97 
98 	fsnotify_unmount_inodes(sb);
99 	fsnotify_clear_marks_by_sb(sb);
100 	/* Wait for outstanding object references from connectors */
101 	wait_var_event(fsnotify_sb_watched_objects(sb),
102 		       !atomic_long_read(fsnotify_sb_watched_objects(sb)));
103 	WARN_ON(fsnotify_sb_has_priority_watchers(sb, FSNOTIFY_PRIO_CONTENT));
104 	WARN_ON(fsnotify_sb_has_priority_watchers(sb,
105 						  FSNOTIFY_PRIO_PRE_CONTENT));
106 }
107 
108 void fsnotify_sb_free(struct super_block *sb)
109 {
110 	kfree(sb->s_fsnotify_info);
111 }
112 
113 /*
114  * Given an inode, first check if we care what happens to our children.  Inotify
115  * and dnotify both tell their parents about events.  If we care about any event
116  * on a child we run all of our children and set a dentry flag saying that the
117  * parent cares.  Thus when an event happens on a child it can quickly tell
118  * if there is a need to find a parent and send the event to the parent.
119  */
120 void fsnotify_set_children_dentry_flags(struct inode *inode)
121 {
122 	struct dentry *alias;
123 
124 	if (!S_ISDIR(inode->i_mode))
125 		return;
126 
127 	spin_lock(&inode->i_lock);
128 	/* run all of the dentries associated with this inode.  Since this is a
129 	 * directory, there damn well better only be one item on this list */
130 	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
131 		struct dentry *child;
132 
133 		/* run all of the children of the original inode and fix their
134 		 * d_flags to indicate parental interest (their parent is the
135 		 * original inode) */
136 		spin_lock(&alias->d_lock);
137 		hlist_for_each_entry(child, &alias->d_children, d_sib) {
138 			if (!child->d_inode)
139 				continue;
140 
141 			spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
142 			child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
143 			spin_unlock(&child->d_lock);
144 		}
145 		spin_unlock(&alias->d_lock);
146 	}
147 	spin_unlock(&inode->i_lock);
148 }
149 
150 /*
151  * Lazily clear false positive PARENT_WATCHED flag for child whose parent had
152  * stopped watching children.
153  */
154 static void fsnotify_clear_child_dentry_flag(struct inode *pinode,
155 					     struct dentry *dentry)
156 {
157 	spin_lock(&dentry->d_lock);
158 	/*
159 	 * d_lock is a sufficient barrier to prevent observing a non-watched
160 	 * parent state from before the fsnotify_set_children_dentry_flags()
161 	 * or fsnotify_update_flags() call that had set PARENT_WATCHED.
162 	 */
163 	if (!fsnotify_inode_watches_children(pinode))
164 		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
165 	spin_unlock(&dentry->d_lock);
166 }
167 
168 /* Are inode/sb/mount interested in parent and name info with this event? */
169 static bool fsnotify_event_needs_parent(struct inode *inode, __u32 mnt_mask,
170 					__u32 mask)
171 {
172 	__u32 marks_mask = 0;
173 
174 	/* We only send parent/name to inode/sb/mount for events on non-dir */
175 	if (mask & FS_ISDIR)
176 		return false;
177 
178 	/*
179 	 * All events that are possible on child can also may be reported with
180 	 * parent/name info to inode/sb/mount.  Otherwise, a watching parent
181 	 * could result in events reported with unexpected name info to sb/mount.
182 	 */
183 	BUILD_BUG_ON(FS_EVENTS_POSS_ON_CHILD & ~FS_EVENTS_POSS_TO_PARENT);
184 
185 	/* Did either inode/sb/mount subscribe for events with parent/name? */
186 	marks_mask |= fsnotify_parent_needed_mask(inode->i_fsnotify_mask);
187 	marks_mask |= fsnotify_parent_needed_mask(inode->i_sb->s_fsnotify_mask);
188 	marks_mask |= fsnotify_parent_needed_mask(mnt_mask);
189 
190 	/* Did they subscribe for this event with parent/name info? */
191 	return mask & marks_mask;
192 }
193 
194 /* Are there any inode/mount/sb objects that are interested in this event? */
195 static inline bool fsnotify_object_watched(struct inode *inode, __u32 mnt_mask,
196 					   __u32 mask)
197 {
198 	__u32 marks_mask = inode->i_fsnotify_mask | mnt_mask |
199 			   inode->i_sb->s_fsnotify_mask;
200 
201 	return mask & marks_mask & ALL_FSNOTIFY_EVENTS;
202 }
203 
204 /*
205  * Notify this dentry's parent about a child's events with child name info
206  * if parent is watching or if inode/sb/mount are interested in events with
207  * parent and name info.
208  *
209  * Notify only the child without name info if parent is not watching and
210  * inode/sb/mount are not interested in events with parent and name info.
211  */
212 int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
213 		      int data_type)
214 {
215 	const struct path *path = fsnotify_data_path(data, data_type);
216 	__u32 mnt_mask = path ? real_mount(path->mnt)->mnt_fsnotify_mask : 0;
217 	struct inode *inode = d_inode(dentry);
218 	struct dentry *parent;
219 	bool parent_watched = dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED;
220 	bool parent_needed, parent_interested;
221 	__u32 p_mask;
222 	struct inode *p_inode = NULL;
223 	struct name_snapshot name;
224 	struct qstr *file_name = NULL;
225 	int ret = 0;
226 
227 	/* Optimize the likely case of nobody watching this path */
228 	if (likely(!parent_watched &&
229 		   !fsnotify_object_watched(inode, mnt_mask, mask)))
230 		return 0;
231 
232 	parent = NULL;
233 	parent_needed = fsnotify_event_needs_parent(inode, mnt_mask, mask);
234 	if (!parent_watched && !parent_needed)
235 		goto notify;
236 
237 	/* Does parent inode care about events on children? */
238 	parent = dget_parent(dentry);
239 	p_inode = parent->d_inode;
240 	p_mask = fsnotify_inode_watches_children(p_inode);
241 	if (unlikely(parent_watched && !p_mask))
242 		fsnotify_clear_child_dentry_flag(p_inode, dentry);
243 
244 	/*
245 	 * Include parent/name in notification either if some notification
246 	 * groups require parent info or the parent is interested in this event.
247 	 */
248 	parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS;
249 	if (parent_needed || parent_interested) {
250 		/* When notifying parent, child should be passed as data */
251 		WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type));
252 
253 		/* Notify both parent and child with child name info */
254 		take_dentry_name_snapshot(&name, dentry);
255 		file_name = &name.name;
256 		if (parent_interested)
257 			mask |= FS_EVENT_ON_CHILD;
258 	}
259 
260 notify:
261 	ret = fsnotify(mask, data, data_type, p_inode, file_name, inode, 0);
262 
263 	if (file_name)
264 		release_dentry_name_snapshot(&name);
265 	dput(parent);
266 
267 	return ret;
268 }
269 EXPORT_SYMBOL_GPL(__fsnotify_parent);
270 
271 static int fsnotify_handle_inode_event(struct fsnotify_group *group,
272 				       struct fsnotify_mark *inode_mark,
273 				       u32 mask, const void *data, int data_type,
274 				       struct inode *dir, const struct qstr *name,
275 				       u32 cookie)
276 {
277 	const struct path *path = fsnotify_data_path(data, data_type);
278 	struct inode *inode = fsnotify_data_inode(data, data_type);
279 	const struct fsnotify_ops *ops = group->ops;
280 
281 	if (WARN_ON_ONCE(!ops->handle_inode_event))
282 		return 0;
283 
284 	if (WARN_ON_ONCE(!inode && !dir))
285 		return 0;
286 
287 	if ((inode_mark->flags & FSNOTIFY_MARK_FLAG_EXCL_UNLINK) &&
288 	    path && d_unlinked(path->dentry))
289 		return 0;
290 
291 	/* Check interest of this mark in case event was sent with two marks */
292 	if (!(mask & inode_mark->mask & ALL_FSNOTIFY_EVENTS))
293 		return 0;
294 
295 	return ops->handle_inode_event(inode_mark, mask, inode, dir, name, cookie);
296 }
297 
298 static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
299 				 const void *data, int data_type,
300 				 struct inode *dir, const struct qstr *name,
301 				 u32 cookie, struct fsnotify_iter_info *iter_info)
302 {
303 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
304 	struct fsnotify_mark *parent_mark = fsnotify_iter_parent_mark(iter_info);
305 	int ret;
306 
307 	if (WARN_ON_ONCE(fsnotify_iter_sb_mark(iter_info)) ||
308 	    WARN_ON_ONCE(fsnotify_iter_vfsmount_mark(iter_info)))
309 		return 0;
310 
311 	/*
312 	 * For FS_RENAME, 'dir' is old dir and 'data' is new dentry.
313 	 * The only ->handle_inode_event() backend that supports FS_RENAME is
314 	 * dnotify, where it means file was renamed within same parent.
315 	 */
316 	if (mask & FS_RENAME) {
317 		struct dentry *moved = fsnotify_data_dentry(data, data_type);
318 
319 		if (dir != moved->d_parent->d_inode)
320 			return 0;
321 	}
322 
323 	if (parent_mark) {
324 		ret = fsnotify_handle_inode_event(group, parent_mark, mask,
325 						  data, data_type, dir, name, 0);
326 		if (ret)
327 			return ret;
328 	}
329 
330 	if (!inode_mark)
331 		return 0;
332 
333 	if (mask & FS_EVENT_ON_CHILD) {
334 		/*
335 		 * Some events can be sent on both parent dir and child marks
336 		 * (e.g. FS_ATTRIB).  If both parent dir and child are
337 		 * watching, report the event once to parent dir with name (if
338 		 * interested) and once to child without name (if interested).
339 		 * The child watcher is expecting an event without a file name
340 		 * and without the FS_EVENT_ON_CHILD flag.
341 		 */
342 		mask &= ~FS_EVENT_ON_CHILD;
343 		dir = NULL;
344 		name = NULL;
345 	}
346 
347 	return fsnotify_handle_inode_event(group, inode_mark, mask, data, data_type,
348 					   dir, name, cookie);
349 }
350 
351 static int send_to_group(__u32 mask, const void *data, int data_type,
352 			 struct inode *dir, const struct qstr *file_name,
353 			 u32 cookie, struct fsnotify_iter_info *iter_info)
354 {
355 	struct fsnotify_group *group = NULL;
356 	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
357 	__u32 marks_mask = 0;
358 	__u32 marks_ignore_mask = 0;
359 	bool is_dir = mask & FS_ISDIR;
360 	struct fsnotify_mark *mark;
361 	int type;
362 
363 	if (!iter_info->report_mask)
364 		return 0;
365 
366 	/* clear ignored on inode modification */
367 	if (mask & FS_MODIFY) {
368 		fsnotify_foreach_iter_mark_type(iter_info, mark, type) {
369 			if (!(mark->flags &
370 			      FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
371 				mark->ignore_mask = 0;
372 		}
373 	}
374 
375 	/* Are any of the group marks interested in this event? */
376 	fsnotify_foreach_iter_mark_type(iter_info, mark, type) {
377 		group = mark->group;
378 		marks_mask |= mark->mask;
379 		marks_ignore_mask |=
380 			fsnotify_effective_ignore_mask(mark, is_dir, type);
381 	}
382 
383 	pr_debug("%s: group=%p mask=%x marks_mask=%x marks_ignore_mask=%x data=%p data_type=%d dir=%p cookie=%d\n",
384 		 __func__, group, mask, marks_mask, marks_ignore_mask,
385 		 data, data_type, dir, cookie);
386 
387 	if (!(test_mask & marks_mask & ~marks_ignore_mask))
388 		return 0;
389 
390 	if (group->ops->handle_event) {
391 		return group->ops->handle_event(group, mask, data, data_type, dir,
392 						file_name, cookie, iter_info);
393 	}
394 
395 	return fsnotify_handle_event(group, mask, data, data_type, dir,
396 				     file_name, cookie, iter_info);
397 }
398 
399 static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)
400 {
401 	struct fsnotify_mark_connector *conn;
402 	struct hlist_node *node = NULL;
403 
404 	conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
405 	if (conn)
406 		node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu);
407 
408 	return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
409 }
410 
411 static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark)
412 {
413 	struct hlist_node *node = NULL;
414 
415 	if (mark)
416 		node = srcu_dereference(mark->obj_list.next,
417 					&fsnotify_mark_srcu);
418 
419 	return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
420 }
421 
422 /*
423  * iter_info is a multi head priority queue of marks.
424  * Pick a subset of marks from queue heads, all with the same group
425  * and set the report_mask to a subset of the selected marks.
426  * Returns false if there are no more groups to iterate.
427  */
428 static bool fsnotify_iter_select_report_types(
429 		struct fsnotify_iter_info *iter_info)
430 {
431 	struct fsnotify_group *max_prio_group = NULL;
432 	struct fsnotify_mark *mark;
433 	int type;
434 
435 	/* Choose max prio group among groups of all queue heads */
436 	fsnotify_foreach_iter_type(type) {
437 		mark = iter_info->marks[type];
438 		if (mark &&
439 		    fsnotify_compare_groups(max_prio_group, mark->group) > 0)
440 			max_prio_group = mark->group;
441 	}
442 
443 	if (!max_prio_group)
444 		return false;
445 
446 	/* Set the report mask for marks from same group as max prio group */
447 	iter_info->current_group = max_prio_group;
448 	iter_info->report_mask = 0;
449 	fsnotify_foreach_iter_type(type) {
450 		mark = iter_info->marks[type];
451 		if (mark && mark->group == iter_info->current_group) {
452 			/*
453 			 * FSNOTIFY_ITER_TYPE_PARENT indicates that this inode
454 			 * is watching children and interested in this event,
455 			 * which is an event possible on child.
456 			 * But is *this mark* watching children?
457 			 */
458 			if (type == FSNOTIFY_ITER_TYPE_PARENT &&
459 			    !(mark->mask & FS_EVENT_ON_CHILD) &&
460 			    !(fsnotify_ignore_mask(mark) & FS_EVENT_ON_CHILD))
461 				continue;
462 
463 			fsnotify_iter_set_report_type(iter_info, type);
464 		}
465 	}
466 
467 	return true;
468 }
469 
470 /*
471  * Pop from iter_info multi head queue, the marks that belong to the group of
472  * current iteration step.
473  */
474 static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
475 {
476 	struct fsnotify_mark *mark;
477 	int type;
478 
479 	/*
480 	 * We cannot use fsnotify_foreach_iter_mark_type() here because we
481 	 * may need to advance a mark of type X that belongs to current_group
482 	 * but was not selected for reporting.
483 	 */
484 	fsnotify_foreach_iter_type(type) {
485 		mark = iter_info->marks[type];
486 		if (mark && mark->group == iter_info->current_group)
487 			iter_info->marks[type] =
488 				fsnotify_next_mark(iter_info->marks[type]);
489 	}
490 }
491 
492 /*
493  * fsnotify - This is the main call to fsnotify.
494  *
495  * The VFS calls into hook specific functions in linux/fsnotify.h.
496  * Those functions then in turn call here.  Here will call out to all of the
497  * registered fsnotify_group.  Those groups can then use the notification event
498  * in whatever means they feel necessary.
499  *
500  * @mask:	event type and flags
501  * @data:	object that event happened on
502  * @data_type:	type of object for fanotify_data_XXX() accessors
503  * @dir:	optional directory associated with event -
504  *		if @file_name is not NULL, this is the directory that
505  *		@file_name is relative to
506  * @file_name:	optional file name associated with event
507  * @inode:	optional inode associated with event -
508  *		If @dir and @inode are both non-NULL, event may be
509  *		reported to both.
510  * @cookie:	inotify rename cookie
511  */
512 int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
513 	     const struct qstr *file_name, struct inode *inode, u32 cookie)
514 {
515 	const struct path *path = fsnotify_data_path(data, data_type);
516 	struct super_block *sb = fsnotify_data_sb(data, data_type);
517 	struct fsnotify_sb_info *sbinfo = fsnotify_sb_info(sb);
518 	struct fsnotify_iter_info iter_info = {};
519 	struct mount *mnt = NULL;
520 	struct inode *inode2 = NULL;
521 	struct dentry *moved;
522 	int inode2_type;
523 	int ret = 0;
524 	__u32 test_mask, marks_mask;
525 
526 	if (path)
527 		mnt = real_mount(path->mnt);
528 
529 	if (!inode) {
530 		/* Dirent event - report on TYPE_INODE to dir */
531 		inode = dir;
532 		/* For FS_RENAME, inode is old_dir and inode2 is new_dir */
533 		if (mask & FS_RENAME) {
534 			moved = fsnotify_data_dentry(data, data_type);
535 			inode2 = moved->d_parent->d_inode;
536 			inode2_type = FSNOTIFY_ITER_TYPE_INODE2;
537 		}
538 	} else if (mask & FS_EVENT_ON_CHILD) {
539 		/*
540 		 * Event on child - report on TYPE_PARENT to dir if it is
541 		 * watching children and on TYPE_INODE to child.
542 		 */
543 		inode2 = dir;
544 		inode2_type = FSNOTIFY_ITER_TYPE_PARENT;
545 	}
546 
547 	/*
548 	 * Optimization: srcu_read_lock() has a memory barrier which can
549 	 * be expensive.  It protects walking the *_fsnotify_marks lists.
550 	 * However, if we do not walk the lists, we do not have to do
551 	 * SRCU because we have no references to any objects and do not
552 	 * need SRCU to keep them "alive".
553 	 */
554 	if ((!sbinfo || !sbinfo->sb_marks) &&
555 	    (!mnt || !mnt->mnt_fsnotify_marks) &&
556 	    (!inode || !inode->i_fsnotify_marks) &&
557 	    (!inode2 || !inode2->i_fsnotify_marks))
558 		return 0;
559 
560 	marks_mask = sb->s_fsnotify_mask;
561 	if (mnt)
562 		marks_mask |= mnt->mnt_fsnotify_mask;
563 	if (inode)
564 		marks_mask |= inode->i_fsnotify_mask;
565 	if (inode2)
566 		marks_mask |= inode2->i_fsnotify_mask;
567 
568 
569 	/*
570 	 * If this is a modify event we may need to clear some ignore masks.
571 	 * In that case, the object with ignore masks will have the FS_MODIFY
572 	 * event in its mask.
573 	 * Otherwise, return if none of the marks care about this type of event.
574 	 */
575 	test_mask = (mask & ALL_FSNOTIFY_EVENTS);
576 	if (!(test_mask & marks_mask))
577 		return 0;
578 
579 	iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
580 
581 	if (sbinfo) {
582 		iter_info.marks[FSNOTIFY_ITER_TYPE_SB] =
583 			fsnotify_first_mark(&sbinfo->sb_marks);
584 	}
585 	if (mnt) {
586 		iter_info.marks[FSNOTIFY_ITER_TYPE_VFSMOUNT] =
587 			fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
588 	}
589 	if (inode) {
590 		iter_info.marks[FSNOTIFY_ITER_TYPE_INODE] =
591 			fsnotify_first_mark(&inode->i_fsnotify_marks);
592 	}
593 	if (inode2) {
594 		iter_info.marks[inode2_type] =
595 			fsnotify_first_mark(&inode2->i_fsnotify_marks);
596 	}
597 
598 	/*
599 	 * We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark
600 	 * ignore masks are properly reflected for mount/sb mark notifications.
601 	 * That's why this traversal is so complicated...
602 	 */
603 	while (fsnotify_iter_select_report_types(&iter_info)) {
604 		ret = send_to_group(mask, data, data_type, dir, file_name,
605 				    cookie, &iter_info);
606 
607 		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
608 			goto out;
609 
610 		fsnotify_iter_next(&iter_info);
611 	}
612 	ret = 0;
613 out:
614 	srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx);
615 
616 	return ret;
617 }
618 EXPORT_SYMBOL_GPL(fsnotify);
619 
620 static __init int fsnotify_init(void)
621 {
622 	int ret;
623 
624 	BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 23);
625 
626 	ret = init_srcu_struct(&fsnotify_mark_srcu);
627 	if (ret)
628 		panic("initializing fsnotify_mark_srcu");
629 
630 	fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector,
631 						    SLAB_PANIC);
632 
633 	return 0;
634 }
635 core_initcall(fsnotify_init);
636