2 * Filesystem access notification for Linux
4 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
7 #ifndef __LINUX_FSNOTIFY_BACKEND_H
8 #define __LINUX_FSNOTIFY_BACKEND_H
12 #include <linux/idr.h> /* inotify uses this */
13 #include <linux/fs.h> /* struct inode */
14 #include <linux/list.h>
15 #include <linux/path.h> /* struct path */
16 #include <linux/spinlock.h>
17 #include <linux/types.h>
18 #include <linux/atomic.h>
21 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
22 * convert between them. dnotify only needs conversion at watch creation
23 * so no perf loss there. fanotify isn't defined yet, so it can use the
24 * wholes if it needs more events.
26 #define FS_ACCESS 0x00000001 /* File was accessed */
27 #define FS_MODIFY 0x00000002 /* File was modified */
28 #define FS_ATTRIB 0x00000004 /* Metadata changed */
29 #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
30 #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
31 #define FS_OPEN 0x00000020 /* File was opened */
32 #define FS_MOVED_FROM 0x00000040 /* File was moved from X */
33 #define FS_MOVED_TO 0x00000080 /* File was moved to Y */
34 #define FS_CREATE 0x00000100 /* Subfile was created */
35 #define FS_DELETE 0x00000200 /* Subfile was deleted */
36 #define FS_DELETE_SELF 0x00000400 /* Self was deleted */
37 #define FS_MOVE_SELF 0x00000800 /* Self was moved */
39 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */
40 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
41 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */
43 #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
44 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
46 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
47 #define FS_ISDIR 0x40000000 /* event occurred against dir */
48 #define FS_IN_ONESHOT 0x80000000 /* only send event once */
50 #define FS_DN_RENAME 0x10000000 /* file renamed */
51 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
53 /* This inode cares about things that happen to its children. Always set for
54 * dnotify and inotify. */
55 #define FS_EVENT_ON_CHILD 0x08000000
57 /* This is a list of all events that may get sent to a parernt based on fs event
58 * happening to inodes inside that directory */
59 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
60 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
61 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
62 FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)
64 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
66 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
68 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
69 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
70 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
71 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
72 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
73 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
74 FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
75 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
77 struct fsnotify_group
;
78 struct fsnotify_event
;
80 struct fsnotify_event_private_data
;
81 struct fsnotify_fname
;
84 * Each group much define these ops. The fsnotify infrastructure will call
85 * these operations for each relevant group.
87 * handle_event - main call for a group to handle an fs event
88 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
89 * freeing_mark - called when a mark is being destroyed for some reason. The group
90 * MUST be holding a reference on each mark and that reference must be
91 * dropped in this function. inotify uses this function to send
92 * userspace messages that marks have been removed.
95 int (*handle_event
)(struct fsnotify_group
*group
,
97 struct fsnotify_mark
*inode_mark
,
98 struct fsnotify_mark
*vfsmount_mark
,
99 u32 mask
, void *data
, int data_type
,
100 const unsigned char *file_name
, u32 cookie
);
101 void (*free_group_priv
)(struct fsnotify_group
*group
);
102 void (*freeing_mark
)(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
);
103 void (*free_event
)(struct fsnotify_event
*event
);
107 * all of the information about the original object we want to now send to
108 * a group. If you want to carry more info from the accessing task to the
109 * listener this structure is where you need to be adding fields.
111 struct fsnotify_event
{
112 struct list_head list
;
113 /* inode may ONLY be dereferenced during handle_event(). */
114 struct inode
*inode
; /* either the inode the event happened to or its parent */
115 u32 mask
; /* the type of access, bitwise OR for FS_* event types */
119 * A group is a "thing" that wants to receive notification about filesystem
120 * events. The mask holds the subset of event types this group cares about.
121 * refcnt on a group is up to the implementor and at any moment if it goes 0
122 * everything will be cleaned up.
124 struct fsnotify_group
{
126 * How the refcnt is used is up to each group. When the refcnt hits 0
127 * fsnotify will clean up all of the resources associated with this group.
128 * As an example, the dnotify group will always have a refcnt=1 and that
129 * will never change. Inotify, on the other hand, has a group per
130 * inotify_init() and the refcnt will hit 0 only when that fd has been
133 atomic_t refcnt
; /* things with interest in this group */
135 const struct fsnotify_ops
*ops
; /* how this group handles things */
137 /* needed to send notification to userspace */
138 struct mutex notification_mutex
; /* protect the notification_list */
139 struct list_head notification_list
; /* list of event_holder this group needs to send to userspace */
140 wait_queue_head_t notification_waitq
; /* read() on the notification file blocks on this waitq */
141 unsigned int q_len
; /* events on the queue */
142 unsigned int max_events
; /* maximum events allowed on the list */
144 * Valid fsnotify group priorities. Events are send in order from highest
145 * priority to lowest priority. We default to the lowest priority.
147 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
148 #define FS_PRIO_1 1 /* fanotify content based access control */
149 #define FS_PRIO_2 2 /* fanotify pre-content access */
150 unsigned int priority
;
152 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
153 struct mutex mark_mutex
; /* protect marks_list */
154 atomic_t num_marks
; /* 1 for each mark and 1 for not being
155 * past the point of no return when freeing
157 struct list_head marks_list
; /* all inode marks for this group */
159 struct fasync_struct
*fsn_fa
; /* async notification */
161 struct fsnotify_event
*overflow_event
; /* Event we queue when the
162 * notification list is too
165 /* groups can define private fields here or use the void *private */
168 #ifdef CONFIG_INOTIFY_USER
169 struct inotify_group_private_data
{
172 struct user_struct
*user
;
175 #ifdef CONFIG_FANOTIFY
176 struct fanotify_group_private_data
{
177 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
178 /* allows a group to block waiting for a userspace response */
179 spinlock_t access_lock
;
180 struct list_head access_list
;
181 wait_queue_head_t access_waitq
;
182 atomic_t bypass_perm
;
183 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
185 unsigned int max_marks
;
186 struct user_struct
*user
;
188 #endif /* CONFIG_FANOTIFY */
192 /* when calling fsnotify tell it if the data is a path or inode */
193 #define FSNOTIFY_EVENT_NONE 0
194 #define FSNOTIFY_EVENT_PATH 1
195 #define FSNOTIFY_EVENT_INODE 2
198 * A mark is simply an object attached to an in core inode which allows an
199 * fsnotify listener to indicate they are either no longer interested in events
200 * of a type matching mask or only interested in those events.
202 * These are flushed when an inode is evicted from core and may be flushed
203 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
204 * users (such as dnotify) will flush these when the open fd is closed and not
205 * at inode eviction or modification.
207 * Text in brackets is showing the lock(s) protecting modifications of a
208 * particular entry. obj_lock means either inode->i_lock or
209 * mnt->mnt_root->d_lock depending on the mark type.
211 struct fsnotify_mark
{
212 /* Mask this mark is for [mark->lock, group->mark_mutex] */
214 /* We hold one for presence in g_list. Also one ref for each 'thing'
215 * in kernel that found and may be using this mark. */
217 /* Group this mark is for. Set on mark creation, stable until last ref
219 struct fsnotify_group
*group
;
220 /* List of marks by group->i_fsnotify_marks. Also reused for queueing
221 * mark into destroy_list when it's waiting for the end of SRCU period
222 * before it can be freed. [group->mark_mutex] */
223 struct list_head g_list
;
224 /* Protects inode / mnt pointers, flags, masks */
226 /* List of marks for inode / vfsmount [obj_lock] */
227 struct hlist_node obj_list
;
228 union { /* Object pointer [mark->lock, group->mark_mutex] */
229 struct inode
*inode
; /* inode this mark is associated with */
230 struct vfsmount
*mnt
; /* vfsmount this mark is associated with */
232 /* Events types to ignore [mark->lock, group->mark_mutex] */
234 #define FSNOTIFY_MARK_FLAG_INODE 0x01
235 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
236 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
237 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
238 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10
239 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x20
240 unsigned int flags
; /* flags [mark->lock] */
241 void (*free_mark
)(struct fsnotify_mark
*mark
); /* called on final put+free */
244 #ifdef CONFIG_FSNOTIFY
246 /* called from the vfs helpers */
248 /* main fsnotify call to send events */
249 extern int fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
250 const unsigned char *name
, u32 cookie
);
251 extern int __fsnotify_parent(struct path
*path
, struct dentry
*dentry
, __u32 mask
);
252 extern void __fsnotify_inode_delete(struct inode
*inode
);
253 extern void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
);
254 extern u32
fsnotify_get_cookie(void);
256 static inline int fsnotify_inode_watches_children(struct inode
*inode
)
258 /* FS_EVENT_ON_CHILD is set if the inode may care */
259 if (!(inode
->i_fsnotify_mask
& FS_EVENT_ON_CHILD
))
261 /* this inode might care about child events, does it care about the
262 * specific set of events that can happen on a child? */
263 return inode
->i_fsnotify_mask
& FS_EVENTS_POSS_ON_CHILD
;
267 * Update the dentry with a flag indicating the interest of its parent to receive
268 * filesystem events when those events happens to this dentry->d_inode.
270 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
272 struct dentry
*parent
;
274 assert_spin_locked(&dentry
->d_lock
);
277 * Serialisation of setting PARENT_WATCHED on the dentries is provided
278 * by d_lock. If inotify_inode_watched changes after we have taken
279 * d_lock, the following __fsnotify_update_child_dentry_flags call will
280 * find our entry, so it will spin until we complete here, and update
281 * us with the new state.
283 parent
= dentry
->d_parent
;
284 if (parent
->d_inode
&& fsnotify_inode_watches_children(parent
->d_inode
))
285 dentry
->d_flags
|= DCACHE_FSNOTIFY_PARENT_WATCHED
;
287 dentry
->d_flags
&= ~DCACHE_FSNOTIFY_PARENT_WATCHED
;
291 * fsnotify_d_instantiate - instantiate a dentry for inode
293 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
)
295 __fsnotify_update_dcache_flags(dentry
);
298 /* called from fsnotify listeners, such as fanotify or dnotify */
300 /* create a new group */
301 extern struct fsnotify_group
*fsnotify_alloc_group(const struct fsnotify_ops
*ops
);
302 /* get reference to a group */
303 extern void fsnotify_get_group(struct fsnotify_group
*group
);
304 /* drop reference on a group from fsnotify_alloc_group */
305 extern void fsnotify_put_group(struct fsnotify_group
*group
);
307 extern void fsnotify_destroy_group(struct fsnotify_group
*group
);
308 /* fasync handler function */
309 extern int fsnotify_fasync(int fd
, struct file
*file
, int on
);
310 /* Free event from memory */
311 extern void fsnotify_destroy_event(struct fsnotify_group
*group
,
312 struct fsnotify_event
*event
);
313 /* attach the event to the group notification queue */
314 extern int fsnotify_add_event(struct fsnotify_group
*group
,
315 struct fsnotify_event
*event
,
316 int (*merge
)(struct list_head
*,
317 struct fsnotify_event
*));
318 /* Remove passed event from groups notification queue */
319 extern void fsnotify_remove_event(struct fsnotify_group
*group
, struct fsnotify_event
*event
);
320 /* true if the group notification queue is empty */
321 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group
*group
);
322 /* return, but do not dequeue the first event on the notification queue */
323 extern struct fsnotify_event
*fsnotify_peek_first_event(struct fsnotify_group
*group
);
324 /* return AND dequeue the first event on the notification queue */
325 extern struct fsnotify_event
*fsnotify_remove_first_event(struct fsnotify_group
*group
);
327 /* functions used to manipulate the marks attached to inodes */
329 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
330 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount
*mnt
);
331 /* run all marks associated with an inode and update inode->i_fsnotify_mask */
332 extern void fsnotify_recalc_inode_mask(struct inode
*inode
);
333 extern void fsnotify_init_mark(struct fsnotify_mark
*mark
, void (*free_mark
)(struct fsnotify_mark
*mark
));
334 /* find (and take a reference) to a mark associated with group and inode */
335 extern struct fsnotify_mark
*fsnotify_find_inode_mark(struct fsnotify_group
*group
, struct inode
*inode
);
336 /* find (and take a reference) to a mark associated with group and vfsmount */
337 extern struct fsnotify_mark
*fsnotify_find_vfsmount_mark(struct fsnotify_group
*group
, struct vfsmount
*mnt
);
338 /* copy the values from old into new */
339 extern void fsnotify_duplicate_mark(struct fsnotify_mark
*new, struct fsnotify_mark
*old
);
340 /* set the ignored_mask of a mark */
341 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark
*mark
, __u32 mask
);
342 /* set the mask of a mark (might pin the object into memory */
343 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark
*mark
, __u32 mask
);
344 /* attach the mark to both the group and the inode */
345 extern int fsnotify_add_mark(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
,
346 struct inode
*inode
, struct vfsmount
*mnt
, int allow_dups
);
347 extern int fsnotify_add_mark_locked(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
,
348 struct inode
*inode
, struct vfsmount
*mnt
, int allow_dups
);
349 /* given a group and a mark, flag mark to be freed when all references are dropped */
350 extern void fsnotify_destroy_mark(struct fsnotify_mark
*mark
,
351 struct fsnotify_group
*group
);
352 /* detach mark from inode / mount list, group list, drop inode reference */
353 extern void fsnotify_detach_mark(struct fsnotify_mark
*mark
);
355 extern void fsnotify_free_mark(struct fsnotify_mark
*mark
);
356 /* run all the marks in a group, and clear all of the vfsmount marks */
357 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group
*group
);
358 /* run all the marks in a group, and clear all of the inode marks */
359 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group
*group
);
360 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
361 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group
*group
, unsigned int flags
);
362 extern void fsnotify_get_mark(struct fsnotify_mark
*mark
);
363 extern void fsnotify_put_mark(struct fsnotify_mark
*mark
);
364 extern void fsnotify_unmount_inodes(struct super_block
*sb
);
366 /* put here because inotify does some weird stuff when destroying watches */
367 extern void fsnotify_init_event(struct fsnotify_event
*event
,
368 struct inode
*to_tell
, u32 mask
);
372 static inline int fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
373 const unsigned char *name
, u32 cookie
)
378 static inline int __fsnotify_parent(struct path
*path
, struct dentry
*dentry
, __u32 mask
)
383 static inline void __fsnotify_inode_delete(struct inode
*inode
)
386 static inline void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
)
389 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
392 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
)
395 static inline u32
fsnotify_get_cookie(void)
400 static inline void fsnotify_unmount_inodes(struct super_block
*sb
)
403 #endif /* CONFIG_FSNOTIFY */
405 #endif /* __KERNEL __ */
407 #endif /* __LINUX_FSNOTIFY_BACKEND_H */