summaryrefslogtreecommitdiff
path: root/include/linux/fsnotify_backend.h
blob: 4dd6143db27165dfdf70d01b6e83c3a35da8f7d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Filesystem access notification for Linux
 *
 *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
 */

#ifndef __LINUX_FSNOTIFY_BACKEND_H
#define __LINUX_FSNOTIFY_BACKEND_H

#ifdef __KERNEL__

#include <linux/idr.h> /* inotify uses this */
#include <linux/fs.h> /* struct inode */
#include <linux/list.h>
#include <linux/path.h> /* struct path */
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/atomic.h>
#include <linux/user_namespace.h>
#include <linux/refcount.h>
#include <linux/mempool.h>
#include <linux/sched/mm.h>

/*
 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
 * convert between them.  dnotify only needs conversion at watch creation
 * so no perf loss there.  fanotify isn't defined yet, so it can use the
 * wholes if it needs more events.
 */
#define FS_ACCESS		0x00000001	/* File was accessed */
#define FS_MODIFY		0x00000002	/* File was modified */
#define FS_ATTRIB		0x00000004	/* Metadata changed */
#define FS_CLOSE_WRITE		0x00000008	/* Writable file was closed */
#define FS_CLOSE_NOWRITE	0x00000010	/* Unwritable file closed */
#define FS_OPEN			0x00000020	/* File was opened */
#define FS_MOVED_FROM		0x00000040	/* File was moved from X */
#define FS_MOVED_TO		0x00000080	/* File was moved to Y */
#define FS_CREATE		0x00000100	/* Subfile was created */
#define FS_DELETE		0x00000200	/* Subfile was deleted */
#define FS_DELETE_SELF		0x00000400	/* Self was deleted */
#define FS_MOVE_SELF		0x00000800	/* Self was moved */
#define FS_OPEN_EXEC		0x00001000	/* File was opened for exec */

#define FS_UNMOUNT		0x00002000	/* inode on umount fs */
#define FS_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
#define FS_ERROR		0x00008000	/* Filesystem Error (fanotify) */

/*
 * FS_IN_IGNORED overloads FS_ERROR.  It is only used internally by inotify
 * which does not support FS_ERROR.
 */
#define FS_IN_IGNORED		0x00008000	/* last inotify event here */

#define FS_OPEN_PERM		0x00010000	/* open event in an permission hook */
#define FS_ACCESS_PERM		0x00020000	/* access event in a permissions hook */
#define FS_OPEN_EXEC_PERM	0x00040000	/* open/exec event in a permission hook */

/*
 * Set on inode mark that cares about things that happen to its children.
 * Always set for dnotify and inotify.
 * Set on inode/sb/mount marks that care about parent/name info.
 */
#define FS_EVENT_ON_CHILD	0x08000000

#define FS_RENAME		0x10000000	/* File was renamed */
#define FS_DN_MULTISHOT		0x20000000	/* dnotify multishot */
#define FS_ISDIR		0x40000000	/* event occurred against dir */

#define FS_MOVE			(FS_MOVED_FROM | FS_MOVED_TO)

/*
 * Directory entry modification events - reported only to directory
 * where entry is modified and not to a watching parent.
 * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
 * when a directory entry inside a child subdir changes.
 */
#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | FS_RENAME)

#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
				  FS_OPEN_EXEC_PERM)

/*
 * This is a list of all events that may get sent to a parent that is watching
 * with flag FS_EVENT_ON_CHILD based on fs event on a child of that directory.
 */
#define FS_EVENTS_POSS_ON_CHILD   (ALL_FSNOTIFY_PERM_EVENTS | \
				   FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
				   FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
				   FS_OPEN | FS_OPEN_EXEC)

/*
 * This is a list of all events that may get sent with the parent inode as the
 * @to_tell argument of fsnotify().
 * It may include events that can be sent to an inode/sb/mount mark, but cannot
 * be sent to a parent watching children.
 */
#define FS_EVENTS_POSS_TO_PARENT (FS_EVENTS_POSS_ON_CHILD)

/* Events that can be reported to backends */
#define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
			     FS_EVENTS_POSS_ON_CHILD | \
			     FS_DELETE_SELF | FS_MOVE_SELF | \
			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
			     FS_ERROR)

/* Extra flags that may be reported with event or control handling of events */
#define ALL_FSNOTIFY_FLAGS  (FS_ISDIR | FS_EVENT_ON_CHILD | FS_DN_MULTISHOT)

#define ALL_FSNOTIFY_BITS   (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)

struct fsnotify_group;
struct fsnotify_event;
struct fsnotify_mark;
struct fsnotify_event_private_data;
struct fsnotify_fname;
struct fsnotify_iter_info;

struct mem_cgroup;

/*
 * Each group much define these ops.  The fsnotify infrastructure will call
 * these operations for each relevant group.
 *
 * handle_event - main call for a group to handle an fs event
 * @group:	group to notify
 * @mask:	event type and flags
 * @data:	object that event happened on
 * @data_type:	type of object for fanotify_data_XXX() accessors
 * @dir:	optional directory associated with event -
 *		if @file_name is not NULL, this is the directory that
 *		@file_name is relative to
 * @file_name:	optional file name associated with event
 * @cookie:	inotify rename cookie
 * @iter_info:	array of marks from this group that are interested in the event
 *
 * handle_inode_event - simple variant of handle_event() for groups that only
 *		have inode marks and don't have ignore mask
 * @mark:	mark to notify
 * @mask:	event type and flags
 * @inode:	inode that event happened on
 * @dir:	optional directory associated with event -
 *		if @file_name is not NULL, this is the directory that
 *		@file_name is relative to.
 *		Either @inode or @dir must be non-NULL.
 * @file_name:	optional file name associated with event
 * @cookie:	inotify rename cookie
 *
 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
 * freeing_mark - called when a mark is being destroyed for some reason.  The group
 *		MUST be holding a reference on each mark and that reference must be
 *		dropped in this function.  inotify uses this function to send
 *		userspace messages that marks have been removed.
 */
struct fsnotify_ops {
	int (*handle_event)(struct fsnotify_group *group, u32 mask,
			    const void *data, int data_type, struct inode *dir,
			    const struct qstr *file_name, u32 cookie,
			    struct fsnotify_iter_info *iter_info);
	int (*handle_inode_event)(struct fsnotify_mark *mark, u32 mask,
			    struct inode *inode, struct inode *dir,
			    const struct qstr *file_name, u32 cookie);
	void (*free_group_priv)(struct fsnotify_group *group);
	void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
	void (*free_event)(struct fsnotify_group *group, struct fsnotify_event *event);
	/* called on final put+free to free memory */
	void (*free_mark)(struct fsnotify_mark *mark);
};

/*
 * all of the information about the original object we want to now send to
 * a group.  If you want to carry more info from the accessing task to the
 * listener this structure is where you need to be adding fields.
 */
struct fsnotify_event {
	struct list_head list;
};

/*
 * fsnotify group priorities.
 * Events are sent in order from highest priority to lowest priority.
 */
enum fsnotify_group_prio {
	FSNOTIFY_PRIO_NORMAL = 0,	/* normal notifiers, no permissions */
	FSNOTIFY_PRIO_CONTENT,		/* fanotify permission events */
	FSNOTIFY_PRIO_PRE_CONTENT,	/* fanotify pre-content events */
	__FSNOTIFY_PRIO_NUM
};

/*
 * A group is a "thing" that wants to receive notification about filesystem
 * events.  The mask holds the subset of event types this group cares about.
 * refcnt on a group is up to the implementor and at any moment if it goes 0
 * everything will be cleaned up.
 */
struct fsnotify_group {
	const struct fsnotify_ops *ops;	/* how this group handles things */

	/*
	 * How the refcnt is used is up to each group.  When the refcnt hits 0
	 * fsnotify will clean up all of the resources associated with this group.
	 * As an example, the dnotify group will always have a refcnt=1 and that
	 * will never change.  Inotify, on the other hand, has a group per
	 * inotify_init() and the refcnt will hit 0 only when that fd has been
	 * closed.
	 */
	refcount_t refcnt;		/* things with interest in this group */

	/* needed to send notification to userspace */
	spinlock_t notification_lock;		/* protect the notification_list */
	struct list_head notification_list;	/* list of event_holder this group needs to send to userspace */
	wait_queue_head_t notification_waitq;	/* read() on the notification file blocks on this waitq */
	unsigned int q_len;			/* events on the queue */
	unsigned int max_events;		/* maximum events allowed on the list */
	enum fsnotify_group_prio priority;	/* priority for sending events */
	bool shutdown;		/* group is being shut down, don't queue more events */

#define FSNOTIFY_GROUP_USER	0x01 /* user allocated group */
#define FSNOTIFY_GROUP_DUPS	0x02 /* allow multiple marks per object */
#define FSNOTIFY_GROUP_NOFS	0x04 /* group lock is not direct reclaim safe */
	int flags;
	unsigned int owner_flags;	/* stored flags of mark_mutex owner */

	/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
	struct mutex mark_mutex;	/* protect marks_list */
	atomic_t user_waits;		/* Number of tasks waiting for user
					 * response */
	struct list_head marks_list;	/* all inode marks for this group */

	struct fasync_struct *fsn_fa;    /* async notification */

	struct fsnotify_event *overflow_event;	/* Event we queue when the
						 * notification list is too
						 * full */

	struct mem_cgroup *memcg;	/* memcg to charge allocations */

	/* groups can define private fields here or use the void *private */
	union {
		void *private;
#ifdef CONFIG_INOTIFY_USER
		struct inotify_group_private_data {
			spinlock_t	idr_lock;
			struct idr      idr;
			struct ucounts *ucounts;
		} inotify_data;
#endif
#ifdef CONFIG_FANOTIFY
		struct fanotify_group_private_data {
			/* Hash table of events for merge */
			struct hlist_head *merge_hash;
			/* allows a group to block waiting for a userspace response */
			struct list_head access_list;
			wait_queue_head_t access_waitq;
			int flags;           /* flags from fanotify_init() */
			int f_flags; /* event_f_flags from fanotify_init() */
			struct ucounts *ucounts;
			mempool_t error_events_pool;
		} fanotify_data;
#endif /* CONFIG_FANOTIFY */
	};
};

/*
 * These helpers are used to prevent deadlock when reclaiming inodes with
 * evictable marks of the same group that is allocating a new mark.
 */
static inline void fsnotify_group_lock(struct fsnotify_group *group)
{
	mutex_lock(&group->mark_mutex);
	if (group->flags & FSNOTIFY_GROUP_NOFS)
		group->owner_flags = memalloc_nofs_save();
}

static inline void fsnotify_group_unlock(struct fsnotify_group *group)
{
	if (group->flags & FSNOTIFY_GROUP_NOFS)
		memalloc_nofs_restore(group->owner_flags);
	mutex_unlock(&group->mark_mutex);
}

static inline void fsnotify_group_assert_locked(struct fsnotify_group *group)
{
	WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex));
	if (group->flags & FSNOTIFY_GROUP_NOFS)
		WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
}

/* When calling fsnotify tell it if the data is a path or inode */
enum fsnotify_data_type {
	FSNOTIFY_EVENT_NONE,
	FSNOTIFY_EVENT_PATH,
	FSNOTIFY_EVENT_INODE,
	FSNOTIFY_EVENT_DENTRY,
	FSNOTIFY_EVENT_ERROR,
};

struct fs_error_report {
	int error;
	struct inode *inode;
	struct super_block *sb;
};

static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
{
	switch (data_type) {
	case FSNOTIFY_EVENT_INODE:
		return (struct inode *)data;
	case FSNOTIFY_EVENT_DENTRY:
		return d_inode(data);
	case FSNOTIFY_EVENT_PATH:
		return d_inode(((const struct path *)data)->dentry);
	case FSNOTIFY_EVENT_ERROR:
		return ((struct fs_error_report *)data)->inode;
	default:
		return NULL;
	}
}

static inline struct dentry *fsnotify_data_dentry(const void *data, int data_type)
{
	switch (data_type) {
	case FSNOTIFY_EVENT_DENTRY:
		/* Non const is needed for dget() */
		return (struct dentry *)data;
	case FSNOTIFY_EVENT_PATH:
		return ((const struct path *)data)->dentry;
	default:
		return NULL;
	}
}

static inline const struct path *fsnotify_data_path(const void *data,
						    int data_type)
{
	switch (data_type) {
	case FSNOTIFY_EVENT_PATH:
		return data;
	default:
		return NULL;
	}
}

static inline struct super_block *fsnotify_data_sb(const void *data,
						   int data_type)
{
	switch (data_type) {
	case FSNOTIFY_EVENT_INODE:
		return ((struct inode *)data)->i_sb;
	case FSNOTIFY_EVENT_DENTRY:
		return ((struct dentry *)data)->d_sb;
	case FSNOTIFY_EVENT_PATH:
		return ((const struct path *)data)->dentry->d_sb;
	case FSNOTIFY_EVENT_ERROR:
		return ((struct fs_error_report *) data)->sb;
	default:
		return NULL;
	}
}

static inline struct fs_error_report *fsnotify_data_error_report(
							const void *data,
							int data_type)
{
	switch (data_type) {
	case FSNOTIFY_EVENT_ERROR:
		return (struct fs_error_report *) data;
	default:
		return NULL;
	}
}

/*
 * Index to merged marks iterator array that correlates to a type of watch.
 * The type of watched object can be deduced from the iterator type, but not
 * the other way around, because an event can match different watched objects
 * of the same object type.
 * For example, both parent and child are watching an object of type inode.
 */
enum fsnotify_iter_type {
	FSNOTIFY_ITER_TYPE_INODE,
	FSNOTIFY_ITER_TYPE_VFSMOUNT,
	FSNOTIFY_ITER_TYPE_SB,
	FSNOTIFY_ITER_TYPE_PARENT,
	FSNOTIFY_ITER_TYPE_INODE2,
	FSNOTIFY_ITER_TYPE_COUNT
};

/* The type of object that a mark is attached to */
enum fsnotify_obj_type {
	FSNOTIFY_OBJ_TYPE_ANY = -1,
	FSNOTIFY_OBJ_TYPE_INODE,
	FSNOTIFY_OBJ_TYPE_VFSMOUNT,
	FSNOTIFY_OBJ_TYPE_SB,
	FSNOTIFY_OBJ_TYPE_COUNT,
	FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT
};

static inline bool fsnotify_valid_obj_type(unsigned int obj_type)
{
	return (obj_type < FSNOTIFY_OBJ_TYPE_COUNT);
}

struct fsnotify_iter_info {
	struct fsnotify_mark *marks[FSNOTIFY_ITER_TYPE_COUNT];
	struct fsnotify_group *current_group;
	unsigned int report_mask;
	int srcu_idx;
};

static inline bool fsnotify_iter_should_report_type(
		struct fsnotify_iter_info *iter_info, int iter_type)
{
	return (iter_info->report_mask & (1U << iter_type));
}

static inline void fsnotify_iter_set_report_type(
		struct fsnotify_iter_info *iter_info, int iter_type)
{
	iter_info->report_mask |= (1U << iter_type);
}

static inline struct fsnotify_mark *fsnotify_iter_mark(
		struct fsnotify_iter_info *iter_info, int iter_type)
{
	if (fsnotify_iter_should_report_type(iter_info, iter_type))
		return iter_info->marks[iter_type];
	return NULL;
}

static inline int fsnotify_iter_step(struct fsnotify_iter_info *iter, int type,
				     struct fsnotify_mark **markp)
{
	while (type < FSNOTIFY_ITER_TYPE_COUNT) {
		*markp = fsnotify_iter_mark(iter, type);
		if (*markp)
			break;
		type++;
	}
	return type;
}

#define FSNOTIFY_ITER_FUNCS(name, NAME) \
static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
		struct fsnotify_iter_info *iter_info) \
{ \
	return fsnotify_iter_mark(iter_info, FSNOTIFY_ITER_TYPE_##NAME); \
}

FSNOTIFY_ITER_FUNCS(inode, INODE)
FSNOTIFY_ITER_FUNCS(parent, PARENT)
FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT)
FSNOTIFY_ITER_FUNCS(sb, SB)

#define fsnotify_foreach_iter_type(type) \
	for (type = 0; type < FSNOTIFY_ITER_TYPE_COUNT; type++)
#define fsnotify_foreach_iter_mark_type(iter, mark, type) \
	for (type = 0; \
	     type = fsnotify_iter_step(iter, type, &mark), \
	     type < FSNOTIFY_ITER_TYPE_COUNT; \
	     type++)

/*
 * Inode/vfsmount/sb point to this structure which tracks all marks attached to
 * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
 * structure. We destroy this structure when there are no more marks attached
 * to it. The structure is protected by fsnotify_mark_srcu.
 */
struct fsnotify_mark_connector {
	spinlock_t lock;
	unsigned char type;	/* Type of object [lock] */
	unsigned char prio;	/* Highest priority group */
#define FSNOTIFY_CONN_FLAG_IS_WATCHED	0x01
#define FSNOTIFY_CONN_FLAG_HAS_IREF	0x02
	unsigned short flags;	/* flags [lock] */
	union {
		/* Object pointer [lock] */
		void *obj;
		/* Used listing heads to free after srcu period expires */
		struct fsnotify_mark_connector *destroy_next;
	};
	struct hlist_head list;
};

/*
 * Container for per-sb fsnotify state (sb marks and more).
 * Attached lazily on first marked object on the sb and freed when killing sb.
 */
struct fsnotify_sb_info {
	struct fsnotify_mark_connector __rcu *sb_marks;
	/*
	 * Number of inode/mount/sb objects that are being watched in this sb.
	 * Note that inodes objects are currently double-accounted.
	 *
	 * The value in watched_objects[prio] is the number of objects that are
	 * watched by groups of priority >= prio, so watched_objects[0] is the
	 * total number of watched objects in this sb.
	 */
	atomic_long_t watched_objects[__FSNOTIFY_PRIO_NUM];
};

static inline struct fsnotify_sb_info *fsnotify_sb_info(struct super_block *sb)
{
#ifdef CONFIG_FSNOTIFY
	return READ_ONCE(sb->s_fsnotify_info);
#else
	return NULL;
#endif
}

static inline atomic_long_t *fsnotify_sb_watched_objects(struct super_block *sb)
{
	return &fsnotify_sb_info(sb)->watched_objects[0];
}

/*
 * A mark is simply an object attached to an in core inode which allows an
 * fsnotify listener to indicate they are either no longer interested in events
 * of a type matching mask or only interested in those events.
 *
 * These are flushed when an inode is evicted from core and may be flushed
 * when the inode is modified (as seen by fsnotify_access).  Some fsnotify
 * users (such as dnotify) will flush these when the open fd is closed and not
 * at inode eviction or modification.
 *
 * Text in brackets is showing the lock(s) protecting modifications of a
 * particular entry. obj_lock means either inode->i_lock or
 * mnt->mnt_root->d_lock depending on the mark type.
 */
struct fsnotify_mark {
	/* Mask this mark is for [mark->lock, group->mark_mutex] */
	__u32 mask;
	/* We hold one for presence in g_list. Also one ref for each 'thing'
	 * in kernel that found and may be using this mark. */
	refcount_t refcnt;
	/* Group this mark is for. Set on mark creation, stable until last ref
	 * is dropped */
	struct fsnotify_group *group;
	/* List of marks by group->marks_list. Also reused for queueing
	 * mark into destroy_list when it's waiting for the end of SRCU period
	 * before it can be freed. [group->mark_mutex] */
	struct list_head g_list;
	/* Protects inode / mnt pointers, flags, masks */
	spinlock_t lock;
	/* List of marks for inode / vfsmount [connector->lock, mark ref] */
	struct hlist_node obj_list;
	/* Head of list of marks for an object [mark ref] */
	struct fsnotify_mark_connector *connector;
	/* Events types and flags to ignore [mark->lock, group->mark_mutex] */
	__u32 ignore_mask;
	/* General fsnotify mark flags */
#define FSNOTIFY_MARK_FLAG_ALIVE		0x0001
#define FSNOTIFY_MARK_FLAG_ATTACHED		0x0002
	/* inotify mark flags */
#define FSNOTIFY_MARK_FLAG_EXCL_UNLINK		0x0010
#define FSNOTIFY_MARK_FLAG_IN_ONESHOT		0x0020
	/* fanotify mark flags */
#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY	0x0100
#define FSNOTIFY_MARK_FLAG_NO_IREF		0x0200
#define FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS	0x0400
#define FSNOTIFY_MARK_FLAG_HAS_FSID		0x0800
#define FSNOTIFY_MARK_FLAG_WEAK_FSID		0x1000
	unsigned int flags;		/* flags [mark->lock] */
};

#ifdef CONFIG_FSNOTIFY

/* called from the vfs helpers */

/* main fsnotify call to send events */
extern int fsnotify(__u32 mask, const void *data, int data_type,
		    struct inode *dir, const struct qstr *name,
		    struct inode *inode, u32 cookie);
extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
			   int data_type);
extern void __fsnotify_inode_delete(struct inode *inode);
extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
extern void fsnotify_sb_delete(struct super_block *sb);
extern void fsnotify_sb_free(struct super_block *sb);
extern u32 fsnotify_get_cookie(void);

static inline __u32 fsnotify_parent_needed_mask(__u32 mask)
{
	/* FS_EVENT_ON_CHILD is set on marks that want parent/name info */
	if (!(mask & FS_EVENT_ON_CHILD))
		return 0;
	/*
	 * This object might be watched by a mark that cares about parent/name
	 * info, does it care about the specific set of events that can be
	 * reported with parent/name info?
	 */
	return mask & FS_EVENTS_POSS_TO_PARENT;
}

static inline int fsnotify_inode_watches_children(struct inode *inode)
{
	/* FS_EVENT_ON_CHILD is set if the inode may care */
	if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
		return 0;
	/* this inode might care about child events, does it care about the
	 * specific set of events that can happen on a child? */
	return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
}

/*
 * Update the dentry with a flag indicating the interest of its parent to receive
 * filesystem events when those events happens to this dentry->d_inode.
 */
static inline void fsnotify_update_flags(struct dentry *dentry)
{
	assert_spin_locked(&dentry->d_lock);

	/*
	 * Serialisation of setting PARENT_WATCHED on the dentries is provided
	 * by d_lock. If inotify_inode_watched changes after we have taken
	 * d_lock, the following __fsnotify_update_child_dentry_flags call will
	 * find our entry, so it will spin until we complete here, and update
	 * us with the new state.
	 */
	if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
		dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
	else
		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
}

/* called from fsnotify listeners, such as fanotify or dnotify */

/* create a new group */
extern struct fsnotify_group *fsnotify_alloc_group(
				const struct fsnotify_ops *ops,
				int flags);
/* get reference to a group */
extern void fsnotify_get_group(struct fsnotify_group *group);
/* drop reference on a group from fsnotify_alloc_group */
extern void fsnotify_put_group(struct fsnotify_group *group);
/* group destruction begins, stop queuing new events */
extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
/* destroy group */
extern void fsnotify_destroy_group(struct fsnotify_group *group);
/* fasync handler function */
extern int fsnotify_fasync(int fd, struct file *file, int on);
/* Free event from memory */
extern void fsnotify_destroy_event(struct fsnotify_group *group,
				   struct fsnotify_event *event);
/* attach the event to the group notification queue */
extern int fsnotify_insert_event(struct fsnotify_group *group,
				 struct fsnotify_event *event,
				 int (*merge)(struct fsnotify_group *,
					      struct fsnotify_event *),
				 void (*insert)(struct fsnotify_group *,
						struct fsnotify_event *));

static inline int fsnotify_add_event(struct fsnotify_group *group,
				     struct fsnotify_event *event,
				     int (*merge)(struct fsnotify_group *,
						  struct fsnotify_event *))
{
	return fsnotify_insert_event(group, event, merge, NULL);
}

/* Queue overflow event to a notification group */
static inline void fsnotify_queue_overflow(struct fsnotify_group *group)
{
	fsnotify_add_event(group, group->overflow_event, NULL);
}

static inline bool fsnotify_is_overflow_event(u32 mask)
{
	return mask & FS_Q_OVERFLOW;
}

static inline bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
{
	assert_spin_locked(&group->notification_lock);

	return list_empty(&group->notification_list);
}

extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
/* return, but do not dequeue the first event on the notification queue */
extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
/* return AND dequeue the first event on the notification queue */
extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
/* Remove event queued in the notification list */
extern void fsnotify_remove_queued_event(struct fsnotify_group *group,
					 struct fsnotify_event *event);

/* functions used to manipulate the marks attached to inodes */

/*
 * Canonical "ignore mask" including event flags.
 *
 * Note the subtle semantic difference from the legacy ->ignored_mask.
 * ->ignored_mask traditionally only meant which events should be ignored,
 * while ->ignore_mask also includes flags regarding the type of objects on
 * which events should be ignored.
 */
static inline __u32 fsnotify_ignore_mask(struct fsnotify_mark *mark)
{
	__u32 ignore_mask = mark->ignore_mask;

	/* The event flags in ignore mask take effect */
	if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
		return ignore_mask;

	/*
	 * Legacy behavior:
	 * - Always ignore events on dir
	 * - Ignore events on child if parent is watching children
	 */
	ignore_mask |= FS_ISDIR;
	ignore_mask &= ~FS_EVENT_ON_CHILD;
	ignore_mask |= mark->mask & FS_EVENT_ON_CHILD;

	return ignore_mask;
}

/* Legacy ignored_mask - only event types to ignore */
static inline __u32 fsnotify_ignored_events(struct fsnotify_mark *mark)
{
	return mark->ignore_mask & ALL_FSNOTIFY_EVENTS;
}

/*
 * Check if mask (or ignore mask) should be applied depending if victim is a
 * directory and whether it is reported to a watching parent.
 */
static inline bool fsnotify_mask_applicable(__u32 mask, bool is_dir,
					    int iter_type)
{
	/* Should mask be applied to a directory? */
	if (is_dir && !(mask & FS_ISDIR))
		return false;

	/* Should mask be applied to a child? */
	if (iter_type == FSNOTIFY_ITER_TYPE_PARENT &&
	    !(mask & FS_EVENT_ON_CHILD))
		return false;

	return true;
}

/*
 * Effective ignore mask taking into account if event victim is a
 * directory and whether it is reported to a watching parent.
 */
static inline __u32 fsnotify_effective_ignore_mask(struct fsnotify_mark *mark,
						   bool is_dir, int iter_type)
{
	__u32 ignore_mask = fsnotify_ignored_events(mark);

	if (!ignore_mask)
		return 0;

	/* For non-dir and non-child, no need to consult the event flags */
	if (!is_dir && iter_type != FSNOTIFY_ITER_TYPE_PARENT)
		return ignore_mask;

	ignore_mask = fsnotify_ignore_mask(mark);
	if (!fsnotify_mask_applicable(ignore_mask, is_dir, iter_type))
		return 0;

	return ignore_mask & ALL_FSNOTIFY_EVENTS;
}

/* Get mask for calculating object interest taking ignore mask into account */
static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark)
{
	__u32 mask = mark->mask;

	if (!fsnotify_ignored_events(mark))
		return mask;

	/* Interest in FS_MODIFY may be needed for clearing ignore mask */
	if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
		mask |= FS_MODIFY;

	/*
	 * If mark is interested in ignoring events on children, the object must
	 * show interest in those events for fsnotify_parent() to notice it.
	 */
	return mask | mark->ignore_mask;
}

/* Get mask of events for a list of marks */
extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn);
/* Calculate mask of events for a list of marks */
extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
extern void fsnotify_init_mark(struct fsnotify_mark *mark,
			       struct fsnotify_group *group);
/* Find mark belonging to given group in the list of marks */
struct fsnotify_mark *fsnotify_find_mark(void *obj, unsigned int obj_type,
					 struct fsnotify_group *group);
/* attach the mark to the object */
int fsnotify_add_mark(struct fsnotify_mark *mark, void *obj,
		      unsigned int obj_type, int add_flags);
int fsnotify_add_mark_locked(struct fsnotify_mark *mark, void *obj,
			     unsigned int obj_type, int add_flags);

/* attach the mark to the inode */
static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
					  struct inode *inode,
					  int add_flags)
{
	return fsnotify_add_mark(mark, inode, FSNOTIFY_OBJ_TYPE_INODE,
				 add_flags);
}
static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark,
						 struct inode *inode,
						 int add_flags)
{
	return fsnotify_add_mark_locked(mark, inode, FSNOTIFY_OBJ_TYPE_INODE,
					add_flags);
}

static inline struct fsnotify_mark *fsnotify_find_inode_mark(
						struct inode *inode,
						struct fsnotify_group *group)
{
	return fsnotify_find_mark(inode, FSNOTIFY_OBJ_TYPE_INODE, group);
}

/* given a group and a mark, flag mark to be freed when all references are dropped */
extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
				  struct fsnotify_group *group);
/* detach mark from inode / mount list, group list, drop inode reference */
extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
/* free mark */
extern void fsnotify_free_mark(struct fsnotify_mark *mark);
/* Wait until all marks queued for destruction are destroyed */
extern void fsnotify_wait_marks_destroyed(void);
/* Clear all of the marks of a group attached to a given object type */
extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group,
					  unsigned int obj_type);
/* run all the marks in a group, and clear all of the vfsmount marks */
static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
{
	fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT);
}
/* run all the marks in a group, and clear all of the inode marks */
static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
{
	fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_INODE);
}
/* run all the marks in a group, and clear all of the sn marks */
static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group *group)
{
	fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_SB);
}
extern void fsnotify_get_mark(struct fsnotify_mark *mark);
extern void fsnotify_put_mark(struct fsnotify_mark *mark);
extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);

static inline void fsnotify_init_event(struct fsnotify_event *event)
{
	INIT_LIST_HEAD(&event->list);
}

#else

static inline int fsnotify(__u32 mask, const void *data, int data_type,
			   struct inode *dir, const struct qstr *name,
			   struct inode *inode, u32 cookie)
{
	return 0;
}

static inline int __fsnotify_parent(struct dentry *dentry, __u32 mask,
				  const void *data, int data_type)
{
	return 0;
}

static inline void __fsnotify_inode_delete(struct inode *inode)
{}

static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
{}

static inline void fsnotify_sb_delete(struct super_block *sb)
{}

static inline void fsnotify_sb_free(struct super_block *sb)
{}

static inline void fsnotify_update_flags(struct dentry *dentry)
{}

static inline u32 fsnotify_get_cookie(void)
{
	return 0;
}

static inline void fsnotify_unmount_inodes(struct super_block *sb)
{}

#endif	/* CONFIG_FSNOTIFY */

#endif	/* __KERNEL __ */

#endif	/* __LINUX_FSNOTIFY_BACKEND_H */