1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Filesystem access notification for Linux
4 *
5 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
6 */
7
8#ifndef __LINUX_FSNOTIFY_BACKEND_H
9#define __LINUX_FSNOTIFY_BACKEND_H
10
11#ifdef __KERNEL__
12
13#include <linux/idr.h> /* inotify uses this */
14#include <linux/fs.h> /* struct inode */
15#include <linux/list.h>
16#include <linux/path.h> /* struct path */
17#include <linux/spinlock.h>
18#include <linux/types.h>
19#include <linux/atomic.h>
20#include <linux/user_namespace.h>
21#include <linux/refcount.h>
22#include <linux/mempool.h>
23#include <linux/sched/mm.h>
24
25/*
26 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
27 * convert between them. dnotify only needs conversion at watch creation
28 * so no perf loss there. fanotify isn't defined yet, so it can use the
29 * wholes if it needs more events.
30 */
31#define FS_ACCESS 0x00000001 /* File was accessed */
32#define FS_MODIFY 0x00000002 /* File was modified */
33#define FS_ATTRIB 0x00000004 /* Metadata changed */
34#define FS_CLOSE_WRITE 0x00000008 /* Writable file was closed */
35#define FS_CLOSE_NOWRITE 0x00000010 /* Unwritable file closed */
36#define FS_OPEN 0x00000020 /* File was opened */
37#define FS_MOVED_FROM 0x00000040 /* File was moved from X */
38#define FS_MOVED_TO 0x00000080 /* File was moved to Y */
39#define FS_CREATE 0x00000100 /* Subfile was created */
40#define FS_DELETE 0x00000200 /* Subfile was deleted */
41#define FS_DELETE_SELF 0x00000400 /* Self was deleted */
42#define FS_MOVE_SELF 0x00000800 /* Self was moved */
43#define FS_OPEN_EXEC 0x00001000 /* File was opened for exec */
44
45#define FS_UNMOUNT 0x00002000 /* inode on umount fs */
46#define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
47#define FS_ERROR 0x00008000 /* Filesystem Error (fanotify) */
48
49/*
50 * FS_IN_IGNORED overloads FS_ERROR. It is only used internally by inotify
51 * which does not support FS_ERROR.
52 */
53#define FS_IN_IGNORED 0x00008000 /* last inotify event here */
54
55#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
56#define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
57#define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */
58
59/*
60 * Set on inode mark that cares about things that happen to its children.
61 * Always set for dnotify and inotify.
62 * Set on inode/sb/mount marks that care about parent/name info.
63 */
64#define FS_EVENT_ON_CHILD 0x08000000
65
66#define FS_RENAME 0x10000000 /* File was renamed */
67#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
68#define FS_ISDIR 0x40000000 /* event occurred against dir */
69
70#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
71
72/*
73 * Directory entry modification events - reported only to directory
74 * where entry is modified and not to a watching parent.
75 * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
76 * when a directory entry inside a child subdir changes.
77 */
78#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | FS_RENAME)
79
80#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
81 FS_OPEN_EXEC_PERM)
82
83/*
84 * This is a list of all events that may get sent to a parent that is watching
85 * with flag FS_EVENT_ON_CHILD based on fs event on a child of that directory.
86 */
87#define FS_EVENTS_POSS_ON_CHILD (ALL_FSNOTIFY_PERM_EVENTS | \
88 FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
89 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
90 FS_OPEN | FS_OPEN_EXEC)
91
92/*
93 * This is a list of all events that may get sent with the parent inode as the
94 * @to_tell argument of fsnotify().
95 * It may include events that can be sent to an inode/sb/mount mark, but cannot
96 * be sent to a parent watching children.
97 */
98#define FS_EVENTS_POSS_TO_PARENT (FS_EVENTS_POSS_ON_CHILD)
99
100/* Events that can be reported to backends */
101#define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
102 FS_EVENTS_POSS_ON_CHILD | \
103 FS_DELETE_SELF | FS_MOVE_SELF | \
104 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
105 FS_ERROR)
106
107/* Extra flags that may be reported with event or control handling of events */
108#define ALL_FSNOTIFY_FLAGS (FS_ISDIR | FS_EVENT_ON_CHILD | FS_DN_MULTISHOT)
109
110#define ALL_FSNOTIFY_BITS (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
111
112struct fsnotify_group;
113struct fsnotify_event;
114struct fsnotify_mark;
115struct fsnotify_event_private_data;
116struct fsnotify_fname;
117struct fsnotify_iter_info;
118
119struct mem_cgroup;
120
121/*
122 * Each group much define these ops. The fsnotify infrastructure will call
123 * these operations for each relevant group.
124 *
125 * handle_event - main call for a group to handle an fs event
126 * @group: group to notify
127 * @mask: event type and flags
128 * @data: object that event happened on
129 * @data_type: type of object for fanotify_data_XXX() accessors
130 * @dir: optional directory associated with event -
131 * if @file_name is not NULL, this is the directory that
132 * @file_name is relative to
133 * @file_name: optional file name associated with event
134 * @cookie: inotify rename cookie
135 * @iter_info: array of marks from this group that are interested in the event
136 *
137 * handle_inode_event - simple variant of handle_event() for groups that only
138 * have inode marks and don't have ignore mask
139 * @mark: mark to notify
140 * @mask: event type and flags
141 * @inode: inode that event happened on
142 * @dir: optional directory associated with event -
143 * if @file_name is not NULL, this is the directory that
144 * @file_name is relative to.
145 * Either @inode or @dir must be non-NULL.
146 * @file_name: optional file name associated with event
147 * @cookie: inotify rename cookie
148 *
149 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
150 * freeing_mark - called when a mark is being destroyed for some reason. The group
151 * MUST be holding a reference on each mark and that reference must be
152 * dropped in this function. inotify uses this function to send
153 * userspace messages that marks have been removed.
154 */
155struct fsnotify_ops {
156 int (*handle_event)(struct fsnotify_group *group, u32 mask,
157 const void *data, int data_type, struct inode *dir,
158 const struct qstr *file_name, u32 cookie,
159 struct fsnotify_iter_info *iter_info);
160 int (*handle_inode_event)(struct fsnotify_mark *mark, u32 mask,
161 struct inode *inode, struct inode *dir,
162 const struct qstr *file_name, u32 cookie);
163 void (*free_group_priv)(struct fsnotify_group *group);
164 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
165 void (*free_event)(struct fsnotify_group *group, struct fsnotify_event *event);
166 /* called on final put+free to free memory */
167 void (*free_mark)(struct fsnotify_mark *mark);
168};
169
170/*
171 * all of the information about the original object we want to now send to
172 * a group. If you want to carry more info from the accessing task to the
173 * listener this structure is where you need to be adding fields.
174 */
175struct fsnotify_event {
176 struct list_head list;
177};
178
179/*
180 * A group is a "thing" that wants to receive notification about filesystem
181 * events. The mask holds the subset of event types this group cares about.
182 * refcnt on a group is up to the implementor and at any moment if it goes 0
183 * everything will be cleaned up.
184 */
185struct fsnotify_group {
186 const struct fsnotify_ops *ops; /* how this group handles things */
187
188 /*
189 * How the refcnt is used is up to each group. When the refcnt hits 0
190 * fsnotify will clean up all of the resources associated with this group.
191 * As an example, the dnotify group will always have a refcnt=1 and that
192 * will never change. Inotify, on the other hand, has a group per
193 * inotify_init() and the refcnt will hit 0 only when that fd has been
194 * closed.
195 */
196 refcount_t refcnt; /* things with interest in this group */
197
198 /* needed to send notification to userspace */
199 spinlock_t notification_lock; /* protect the notification_list */
200 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
201 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
202 unsigned int q_len; /* events on the queue */
203 unsigned int max_events; /* maximum events allowed on the list */
204 /*
205 * Valid fsnotify group priorities. Events are send in order from highest
206 * priority to lowest priority. We default to the lowest priority.
207 */
208 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
209 #define FS_PRIO_1 1 /* fanotify content based access control */
210 #define FS_PRIO_2 2 /* fanotify pre-content access */
211 unsigned int priority;
212 bool shutdown; /* group is being shut down, don't queue more events */
213
214#define FSNOTIFY_GROUP_USER 0x01 /* user allocated group */
215#define FSNOTIFY_GROUP_DUPS 0x02 /* allow multiple marks per object */
216#define FSNOTIFY_GROUP_NOFS 0x04 /* group lock is not direct reclaim safe */
217 int flags;
218 unsigned int owner_flags; /* stored flags of mark_mutex owner */
219
220 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
221 struct mutex mark_mutex; /* protect marks_list */
222 atomic_t user_waits; /* Number of tasks waiting for user
223 * response */
224 struct list_head marks_list; /* all inode marks for this group */
225
226 struct fasync_struct *fsn_fa; /* async notification */
227
228 struct fsnotify_event *overflow_event; /* Event we queue when the
229 * notification list is too
230 * full */
231
232 struct mem_cgroup *memcg; /* memcg to charge allocations */
233
234 /* groups can define private fields here or use the void *private */
235 union {
236 void *private;
237#ifdef CONFIG_INOTIFY_USER
238 struct inotify_group_private_data {
239 spinlock_t idr_lock;
240 struct idr idr;
241 struct ucounts *ucounts;
242 } inotify_data;
243#endif
244#ifdef CONFIG_FANOTIFY
245 struct fanotify_group_private_data {
246 /* Hash table of events for merge */
247 struct hlist_head *merge_hash;
248 /* allows a group to block waiting for a userspace response */
249 struct list_head access_list;
250 wait_queue_head_t access_waitq;
251 int flags; /* flags from fanotify_init() */
252 int f_flags; /* event_f_flags from fanotify_init() */
253 struct ucounts *ucounts;
254 mempool_t error_events_pool;
255 } fanotify_data;
256#endif /* CONFIG_FANOTIFY */
257 };
258};
259
260/*
261 * These helpers are used to prevent deadlock when reclaiming inodes with
262 * evictable marks of the same group that is allocating a new mark.
263 */
264static inline void fsnotify_group_lock(struct fsnotify_group *group)
265{
266 mutex_lock(&group->mark_mutex);
267 if (group->flags & FSNOTIFY_GROUP_NOFS)
268 group->owner_flags = memalloc_nofs_save();
269}
270
271static inline void fsnotify_group_unlock(struct fsnotify_group *group)
272{
273 if (group->flags & FSNOTIFY_GROUP_NOFS)
274 memalloc_nofs_restore(flags: group->owner_flags);
275 mutex_unlock(lock: &group->mark_mutex);
276}
277
278static inline void fsnotify_group_assert_locked(struct fsnotify_group *group)
279{
280 WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex));
281 if (group->flags & FSNOTIFY_GROUP_NOFS)
282 WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
283}
284
285/* When calling fsnotify tell it if the data is a path or inode */
286enum fsnotify_data_type {
287 FSNOTIFY_EVENT_NONE,
288 FSNOTIFY_EVENT_PATH,
289 FSNOTIFY_EVENT_INODE,
290 FSNOTIFY_EVENT_DENTRY,
291 FSNOTIFY_EVENT_ERROR,
292};
293
294struct fs_error_report {
295 int error;
296 struct inode *inode;
297 struct super_block *sb;
298};
299
300static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
301{
302 switch (data_type) {
303 case FSNOTIFY_EVENT_INODE:
304 return (struct inode *)data;
305 case FSNOTIFY_EVENT_DENTRY:
306 return d_inode(dentry: data);
307 case FSNOTIFY_EVENT_PATH:
308 return d_inode(dentry: ((const struct path *)data)->dentry);
309 case FSNOTIFY_EVENT_ERROR:
310 return ((struct fs_error_report *)data)->inode;
311 default:
312 return NULL;
313 }
314}
315
316static inline struct dentry *fsnotify_data_dentry(const void *data, int data_type)
317{
318 switch (data_type) {
319 case FSNOTIFY_EVENT_DENTRY:
320 /* Non const is needed for dget() */
321 return (struct dentry *)data;
322 case FSNOTIFY_EVENT_PATH:
323 return ((const struct path *)data)->dentry;
324 default:
325 return NULL;
326 }
327}
328
329static inline const struct path *fsnotify_data_path(const void *data,
330 int data_type)
331{
332 switch (data_type) {
333 case FSNOTIFY_EVENT_PATH:
334 return data;
335 default:
336 return NULL;
337 }
338}
339
340static inline struct super_block *fsnotify_data_sb(const void *data,
341 int data_type)
342{
343 switch (data_type) {
344 case FSNOTIFY_EVENT_INODE:
345 return ((struct inode *)data)->i_sb;
346 case FSNOTIFY_EVENT_DENTRY:
347 return ((struct dentry *)data)->d_sb;
348 case FSNOTIFY_EVENT_PATH:
349 return ((const struct path *)data)->dentry->d_sb;
350 case FSNOTIFY_EVENT_ERROR:
351 return ((struct fs_error_report *) data)->sb;
352 default:
353 return NULL;
354 }
355}
356
357static inline struct fs_error_report *fsnotify_data_error_report(
358 const void *data,
359 int data_type)
360{
361 switch (data_type) {
362 case FSNOTIFY_EVENT_ERROR:
363 return (struct fs_error_report *) data;
364 default:
365 return NULL;
366 }
367}
368
369/*
370 * Index to merged marks iterator array that correlates to a type of watch.
371 * The type of watched object can be deduced from the iterator type, but not
372 * the other way around, because an event can match different watched objects
373 * of the same object type.
374 * For example, both parent and child are watching an object of type inode.
375 */
376enum fsnotify_iter_type {
377 FSNOTIFY_ITER_TYPE_INODE,
378 FSNOTIFY_ITER_TYPE_VFSMOUNT,
379 FSNOTIFY_ITER_TYPE_SB,
380 FSNOTIFY_ITER_TYPE_PARENT,
381 FSNOTIFY_ITER_TYPE_INODE2,
382 FSNOTIFY_ITER_TYPE_COUNT
383};
384
385/* The type of object that a mark is attached to */
386enum fsnotify_obj_type {
387 FSNOTIFY_OBJ_TYPE_ANY = -1,
388 FSNOTIFY_OBJ_TYPE_INODE,
389 FSNOTIFY_OBJ_TYPE_VFSMOUNT,
390 FSNOTIFY_OBJ_TYPE_SB,
391 FSNOTIFY_OBJ_TYPE_COUNT,
392 FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT
393};
394
395static inline bool fsnotify_valid_obj_type(unsigned int obj_type)
396{
397 return (obj_type < FSNOTIFY_OBJ_TYPE_COUNT);
398}
399
400struct fsnotify_iter_info {
401 struct fsnotify_mark *marks[FSNOTIFY_ITER_TYPE_COUNT];
402 struct fsnotify_group *current_group;
403 unsigned int report_mask;
404 int srcu_idx;
405};
406
407static inline bool fsnotify_iter_should_report_type(
408 struct fsnotify_iter_info *iter_info, int iter_type)
409{
410 return (iter_info->report_mask & (1U << iter_type));
411}
412
413static inline void fsnotify_iter_set_report_type(
414 struct fsnotify_iter_info *iter_info, int iter_type)
415{
416 iter_info->report_mask |= (1U << iter_type);
417}
418
419static inline struct fsnotify_mark *fsnotify_iter_mark(
420 struct fsnotify_iter_info *iter_info, int iter_type)
421{
422 if (fsnotify_iter_should_report_type(iter_info, iter_type))
423 return iter_info->marks[iter_type];
424 return NULL;
425}
426
427static inline int fsnotify_iter_step(struct fsnotify_iter_info *iter, int type,
428 struct fsnotify_mark **markp)
429{
430 while (type < FSNOTIFY_ITER_TYPE_COUNT) {
431 *markp = fsnotify_iter_mark(iter_info: iter, iter_type: type);
432 if (*markp)
433 break;
434 type++;
435 }
436 return type;
437}
438
439#define FSNOTIFY_ITER_FUNCS(name, NAME) \
440static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
441 struct fsnotify_iter_info *iter_info) \
442{ \
443 return fsnotify_iter_mark(iter_info, FSNOTIFY_ITER_TYPE_##NAME); \
444}
445
446FSNOTIFY_ITER_FUNCS(inode, INODE)
447FSNOTIFY_ITER_FUNCS(parent, PARENT)
448FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT)
449FSNOTIFY_ITER_FUNCS(sb, SB)
450
451#define fsnotify_foreach_iter_type(type) \
452 for (type = 0; type < FSNOTIFY_ITER_TYPE_COUNT; type++)
453#define fsnotify_foreach_iter_mark_type(iter, mark, type) \
454 for (type = 0; \
455 type = fsnotify_iter_step(iter, type, &mark), \
456 type < FSNOTIFY_ITER_TYPE_COUNT; \
457 type++)
458
459/*
460 * fsnotify_connp_t is what we embed in objects which connector can be attached
461 * to. fsnotify_connp_t * is how we refer from connector back to object.
462 */
463struct fsnotify_mark_connector;
464typedef struct fsnotify_mark_connector __rcu *fsnotify_connp_t;
465
466/*
467 * Inode/vfsmount/sb point to this structure which tracks all marks attached to
468 * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
469 * structure. We destroy this structure when there are no more marks attached
470 * to it. The structure is protected by fsnotify_mark_srcu.
471 */
472struct fsnotify_mark_connector {
473 spinlock_t lock;
474 unsigned short type; /* Type of object [lock] */
475#define FSNOTIFY_CONN_FLAG_HAS_IREF 0x02
476 unsigned short flags; /* flags [lock] */
477 union {
478 /* Object pointer [lock] */
479 fsnotify_connp_t *obj;
480 /* Used listing heads to free after srcu period expires */
481 struct fsnotify_mark_connector *destroy_next;
482 };
483 struct hlist_head list;
484};
485
486/*
487 * A mark is simply an object attached to an in core inode which allows an
488 * fsnotify listener to indicate they are either no longer interested in events
489 * of a type matching mask or only interested in those events.
490 *
491 * These are flushed when an inode is evicted from core and may be flushed
492 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
493 * users (such as dnotify) will flush these when the open fd is closed and not
494 * at inode eviction or modification.
495 *
496 * Text in brackets is showing the lock(s) protecting modifications of a
497 * particular entry. obj_lock means either inode->i_lock or
498 * mnt->mnt_root->d_lock depending on the mark type.
499 */
500struct fsnotify_mark {
501 /* Mask this mark is for [mark->lock, group->mark_mutex] */
502 __u32 mask;
503 /* We hold one for presence in g_list. Also one ref for each 'thing'
504 * in kernel that found and may be using this mark. */
505 refcount_t refcnt;
506 /* Group this mark is for. Set on mark creation, stable until last ref
507 * is dropped */
508 struct fsnotify_group *group;
509 /* List of marks by group->marks_list. Also reused for queueing
510 * mark into destroy_list when it's waiting for the end of SRCU period
511 * before it can be freed. [group->mark_mutex] */
512 struct list_head g_list;
513 /* Protects inode / mnt pointers, flags, masks */
514 spinlock_t lock;
515 /* List of marks for inode / vfsmount [connector->lock, mark ref] */
516 struct hlist_node obj_list;
517 /* Head of list of marks for an object [mark ref] */
518 struct fsnotify_mark_connector *connector;
519 /* Events types and flags to ignore [mark->lock, group->mark_mutex] */
520 __u32 ignore_mask;
521 /* General fsnotify mark flags */
522#define FSNOTIFY_MARK_FLAG_ALIVE 0x0001
523#define FSNOTIFY_MARK_FLAG_ATTACHED 0x0002
524 /* inotify mark flags */
525#define FSNOTIFY_MARK_FLAG_EXCL_UNLINK 0x0010
526#define FSNOTIFY_MARK_FLAG_IN_ONESHOT 0x0020
527 /* fanotify mark flags */
528#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x0100
529#define FSNOTIFY_MARK_FLAG_NO_IREF 0x0200
530#define FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS 0x0400
531#define FSNOTIFY_MARK_FLAG_HAS_FSID 0x0800
532#define FSNOTIFY_MARK_FLAG_WEAK_FSID 0x1000
533 unsigned int flags; /* flags [mark->lock] */
534};
535
536#ifdef CONFIG_FSNOTIFY
537
538/* called from the vfs helpers */
539
540/* main fsnotify call to send events */
541extern int fsnotify(__u32 mask, const void *data, int data_type,
542 struct inode *dir, const struct qstr *name,
543 struct inode *inode, u32 cookie);
544extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
545 int data_type);
546extern void __fsnotify_inode_delete(struct inode *inode);
547extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
548extern void fsnotify_sb_delete(struct super_block *sb);
549extern u32 fsnotify_get_cookie(void);
550
551static inline __u32 fsnotify_parent_needed_mask(__u32 mask)
552{
553 /* FS_EVENT_ON_CHILD is set on marks that want parent/name info */
554 if (!(mask & FS_EVENT_ON_CHILD))
555 return 0;
556 /*
557 * This object might be watched by a mark that cares about parent/name
558 * info, does it care about the specific set of events that can be
559 * reported with parent/name info?
560 */
561 return mask & FS_EVENTS_POSS_TO_PARENT;
562}
563
564static inline int fsnotify_inode_watches_children(struct inode *inode)
565{
566 /* FS_EVENT_ON_CHILD is set if the inode may care */
567 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
568 return 0;
569 /* this inode might care about child events, does it care about the
570 * specific set of events that can happen on a child? */
571 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
572}
573
574/*
575 * Update the dentry with a flag indicating the interest of its parent to receive
576 * filesystem events when those events happens to this dentry->d_inode.
577 */
578static inline void fsnotify_update_flags(struct dentry *dentry)
579{
580 assert_spin_locked(&dentry->d_lock);
581
582 /*
583 * Serialisation of setting PARENT_WATCHED on the dentries is provided
584 * by d_lock. If inotify_inode_watched changes after we have taken
585 * d_lock, the following __fsnotify_update_child_dentry_flags call will
586 * find our entry, so it will spin until we complete here, and update
587 * us with the new state.
588 */
589 if (fsnotify_inode_watches_children(inode: dentry->d_parent->d_inode))
590 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
591 else
592 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
593}
594
595/* called from fsnotify listeners, such as fanotify or dnotify */
596
597/* create a new group */
598extern struct fsnotify_group *fsnotify_alloc_group(
599 const struct fsnotify_ops *ops,
600 int flags);
601/* get reference to a group */
602extern void fsnotify_get_group(struct fsnotify_group *group);
603/* drop reference on a group from fsnotify_alloc_group */
604extern void fsnotify_put_group(struct fsnotify_group *group);
605/* group destruction begins, stop queuing new events */
606extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
607/* destroy group */
608extern void fsnotify_destroy_group(struct fsnotify_group *group);
609/* fasync handler function */
610extern int fsnotify_fasync(int fd, struct file *file, int on);
611/* Free event from memory */
612extern void fsnotify_destroy_event(struct fsnotify_group *group,
613 struct fsnotify_event *event);
614/* attach the event to the group notification queue */
615extern int fsnotify_insert_event(struct fsnotify_group *group,
616 struct fsnotify_event *event,
617 int (*merge)(struct fsnotify_group *,
618 struct fsnotify_event *),
619 void (*insert)(struct fsnotify_group *,
620 struct fsnotify_event *));
621
622static inline int fsnotify_add_event(struct fsnotify_group *group,
623 struct fsnotify_event *event,
624 int (*merge)(struct fsnotify_group *,
625 struct fsnotify_event *))
626{
627 return fsnotify_insert_event(group, event, merge, NULL);
628}
629
630/* Queue overflow event to a notification group */
631static inline void fsnotify_queue_overflow(struct fsnotify_group *group)
632{
633 fsnotify_add_event(group, event: group->overflow_event, NULL);
634}
635
636static inline bool fsnotify_is_overflow_event(u32 mask)
637{
638 return mask & FS_Q_OVERFLOW;
639}
640
641static inline bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
642{
643 assert_spin_locked(&group->notification_lock);
644
645 return list_empty(head: &group->notification_list);
646}
647
648extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
649/* return, but do not dequeue the first event on the notification queue */
650extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
651/* return AND dequeue the first event on the notification queue */
652extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
653/* Remove event queued in the notification list */
654extern void fsnotify_remove_queued_event(struct fsnotify_group *group,
655 struct fsnotify_event *event);
656
657/* functions used to manipulate the marks attached to inodes */
658
659/*
660 * Canonical "ignore mask" including event flags.
661 *
662 * Note the subtle semantic difference from the legacy ->ignored_mask.
663 * ->ignored_mask traditionally only meant which events should be ignored,
664 * while ->ignore_mask also includes flags regarding the type of objects on
665 * which events should be ignored.
666 */
667static inline __u32 fsnotify_ignore_mask(struct fsnotify_mark *mark)
668{
669 __u32 ignore_mask = mark->ignore_mask;
670
671 /* The event flags in ignore mask take effect */
672 if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
673 return ignore_mask;
674
675 /*
676 * Legacy behavior:
677 * - Always ignore events on dir
678 * - Ignore events on child if parent is watching children
679 */
680 ignore_mask |= FS_ISDIR;
681 ignore_mask &= ~FS_EVENT_ON_CHILD;
682 ignore_mask |= mark->mask & FS_EVENT_ON_CHILD;
683
684 return ignore_mask;
685}
686
687/* Legacy ignored_mask - only event types to ignore */
688static inline __u32 fsnotify_ignored_events(struct fsnotify_mark *mark)
689{
690 return mark->ignore_mask & ALL_FSNOTIFY_EVENTS;
691}
692
693/*
694 * Check if mask (or ignore mask) should be applied depending if victim is a
695 * directory and whether it is reported to a watching parent.
696 */
697static inline bool fsnotify_mask_applicable(__u32 mask, bool is_dir,
698 int iter_type)
699{
700 /* Should mask be applied to a directory? */
701 if (is_dir && !(mask & FS_ISDIR))
702 return false;
703
704 /* Should mask be applied to a child? */
705 if (iter_type == FSNOTIFY_ITER_TYPE_PARENT &&
706 !(mask & FS_EVENT_ON_CHILD))
707 return false;
708
709 return true;
710}
711
712/*
713 * Effective ignore mask taking into account if event victim is a
714 * directory and whether it is reported to a watching parent.
715 */
716static inline __u32 fsnotify_effective_ignore_mask(struct fsnotify_mark *mark,
717 bool is_dir, int iter_type)
718{
719 __u32 ignore_mask = fsnotify_ignored_events(mark);
720
721 if (!ignore_mask)
722 return 0;
723
724 /* For non-dir and non-child, no need to consult the event flags */
725 if (!is_dir && iter_type != FSNOTIFY_ITER_TYPE_PARENT)
726 return ignore_mask;
727
728 ignore_mask = fsnotify_ignore_mask(mark);
729 if (!fsnotify_mask_applicable(mask: ignore_mask, is_dir, iter_type))
730 return 0;
731
732 return ignore_mask & ALL_FSNOTIFY_EVENTS;
733}
734
735/* Get mask for calculating object interest taking ignore mask into account */
736static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark)
737{
738 __u32 mask = mark->mask;
739
740 if (!fsnotify_ignored_events(mark))
741 return mask;
742
743 /* Interest in FS_MODIFY may be needed for clearing ignore mask */
744 if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
745 mask |= FS_MODIFY;
746
747 /*
748 * If mark is interested in ignoring events on children, the object must
749 * show interest in those events for fsnotify_parent() to notice it.
750 */
751 return mask | mark->ignore_mask;
752}
753
754/* Get mask of events for a list of marks */
755extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn);
756/* Calculate mask of events for a list of marks */
757extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
758extern void fsnotify_init_mark(struct fsnotify_mark *mark,
759 struct fsnotify_group *group);
760/* Find mark belonging to given group in the list of marks */
761extern struct fsnotify_mark *fsnotify_find_mark(fsnotify_connp_t *connp,
762 struct fsnotify_group *group);
763/* attach the mark to the object */
764extern int fsnotify_add_mark(struct fsnotify_mark *mark,
765 fsnotify_connp_t *connp, unsigned int obj_type,
766 int add_flags);
767extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
768 fsnotify_connp_t *connp,
769 unsigned int obj_type, int add_flags);
770
771/* attach the mark to the inode */
772static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
773 struct inode *inode,
774 int add_flags)
775{
776 return fsnotify_add_mark(mark, connp: &inode->i_fsnotify_marks,
777 obj_type: FSNOTIFY_OBJ_TYPE_INODE, add_flags);
778}
779static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark,
780 struct inode *inode,
781 int add_flags)
782{
783 return fsnotify_add_mark_locked(mark, connp: &inode->i_fsnotify_marks,
784 obj_type: FSNOTIFY_OBJ_TYPE_INODE, add_flags);
785}
786
787/* given a group and a mark, flag mark to be freed when all references are dropped */
788extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
789 struct fsnotify_group *group);
790/* detach mark from inode / mount list, group list, drop inode reference */
791extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
792/* free mark */
793extern void fsnotify_free_mark(struct fsnotify_mark *mark);
794/* Wait until all marks queued for destruction are destroyed */
795extern void fsnotify_wait_marks_destroyed(void);
796/* Clear all of the marks of a group attached to a given object type */
797extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group,
798 unsigned int obj_type);
799/* run all the marks in a group, and clear all of the vfsmount marks */
800static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
801{
802 fsnotify_clear_marks_by_group(group, obj_type: FSNOTIFY_OBJ_TYPE_VFSMOUNT);
803}
804/* run all the marks in a group, and clear all of the inode marks */
805static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
806{
807 fsnotify_clear_marks_by_group(group, obj_type: FSNOTIFY_OBJ_TYPE_INODE);
808}
809/* run all the marks in a group, and clear all of the sn marks */
810static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group *group)
811{
812 fsnotify_clear_marks_by_group(group, obj_type: FSNOTIFY_OBJ_TYPE_SB);
813}
814extern void fsnotify_get_mark(struct fsnotify_mark *mark);
815extern void fsnotify_put_mark(struct fsnotify_mark *mark);
816extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
817extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
818
819static inline void fsnotify_init_event(struct fsnotify_event *event)
820{
821 INIT_LIST_HEAD(list: &event->list);
822}
823
824#else
825
826static inline int fsnotify(__u32 mask, const void *data, int data_type,
827 struct inode *dir, const struct qstr *name,
828 struct inode *inode, u32 cookie)
829{
830 return 0;
831}
832
833static inline int __fsnotify_parent(struct dentry *dentry, __u32 mask,
834 const void *data, int data_type)
835{
836 return 0;
837}
838
839static inline void __fsnotify_inode_delete(struct inode *inode)
840{}
841
842static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
843{}
844
845static inline void fsnotify_sb_delete(struct super_block *sb)
846{}
847
848static inline void fsnotify_update_flags(struct dentry *dentry)
849{}
850
851static inline u32 fsnotify_get_cookie(void)
852{
853 return 0;
854}
855
856static inline void fsnotify_unmount_inodes(struct super_block *sb)
857{}
858
859#endif /* CONFIG_FSNOTIFY */
860
861#endif /* __KERNEL __ */
862
863#endif /* __LINUX_FSNOTIFY_BACKEND_H */
864

source code of linux/include/linux/fsnotify_backend.h