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 * should_send_event - given a group, inode, and mask this function determines
88 * if the group is interested in this event.
89 * handle_event - main call for a group to handle an fs event
90 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
91 * freeing_mark - called when a mark is being destroyed for some reason. The group
92 * MUST be holding a reference on each mark and that reference must be
93 * dropped in this function. inotify uses this function to send
94 * userspace messages that marks have been removed.
97 int (*handle_event
)(struct fsnotify_group
*group
,
99 struct fsnotify_mark
*inode_mark
,
100 struct fsnotify_mark
*vfsmount_mark
,
101 u32 mask
, void *data
, int data_type
,
102 const unsigned char *file_name
, u32 cookie
);
103 void (*free_group_priv
)(struct fsnotify_group
*group
);
104 void (*freeing_mark
)(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
);
105 void (*free_event
)(struct fsnotify_event
*event
);
109 * all of the information about the original object we want to now send to
110 * a group. If you want to carry more info from the accessing task to the
111 * listener this structure is where you need to be adding fields.
113 struct fsnotify_event
{
114 struct list_head list
;
115 /* inode may ONLY be dereferenced during handle_event(). */
116 struct inode
*inode
; /* either the inode the event happened to or its parent */
117 u32 mask
; /* the type of access, bitwise OR for FS_* event types */
121 * A group is a "thing" that wants to receive notification about filesystem
122 * events. The mask holds the subset of event types this group cares about.
123 * refcnt on a group is up to the implementor and at any moment if it goes 0
124 * everything will be cleaned up.
126 struct fsnotify_group
{
128 * How the refcnt is used is up to each group. When the refcnt hits 0
129 * fsnotify will clean up all of the resources associated with this group.
130 * As an example, the dnotify group will always have a refcnt=1 and that
131 * will never change. Inotify, on the other hand, has a group per
132 * inotify_init() and the refcnt will hit 0 only when that fd has been
135 atomic_t refcnt
; /* things with interest in this group */
137 const struct fsnotify_ops
*ops
; /* how this group handles things */
139 /* needed to send notification to userspace */
140 struct mutex notification_mutex
; /* protect the notification_list */
141 struct list_head notification_list
; /* list of event_holder this group needs to send to userspace */
142 wait_queue_head_t notification_waitq
; /* read() on the notification file blocks on this waitq */
143 unsigned int q_len
; /* events on the queue */
144 unsigned int max_events
; /* maximum events allowed on the list */
146 * Valid fsnotify group priorities. Events are send in order from highest
147 * priority to lowest priority. We default to the lowest priority.
149 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
150 #define FS_PRIO_1 1 /* fanotify content based access control */
151 #define FS_PRIO_2 2 /* fanotify pre-content access */
152 unsigned int priority
;
154 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
155 struct mutex mark_mutex
; /* protect marks_list */
156 atomic_t num_marks
; /* 1 for each mark and 1 for not being
157 * past the point of no return when freeing
159 struct list_head marks_list
; /* all inode marks for this group */
161 struct fasync_struct
*fsn_fa
; /* async notification */
163 struct fsnotify_event
*overflow_event
; /* Event we queue when the
164 * notification list is too
167 /* groups can define private fields here or use the void *private */
170 #ifdef CONFIG_INOTIFY_USER
171 struct inotify_group_private_data
{
174 struct user_struct
*user
;
177 #ifdef CONFIG_FANOTIFY
178 struct fanotify_group_private_data
{
179 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
180 /* allows a group to block waiting for a userspace response */
181 spinlock_t access_lock
;
182 struct list_head access_list
;
183 wait_queue_head_t access_waitq
;
184 atomic_t bypass_perm
;
185 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
187 unsigned int max_marks
;
188 struct user_struct
*user
;
190 #endif /* CONFIG_FANOTIFY */
194 /* when calling fsnotify tell it if the data is a path or inode */
195 #define FSNOTIFY_EVENT_NONE 0
196 #define FSNOTIFY_EVENT_PATH 1
197 #define FSNOTIFY_EVENT_INODE 2
200 * Inode specific fields in an fsnotify_mark
202 struct fsnotify_inode_mark
{
203 struct inode
*inode
; /* inode this mark is associated with */
204 struct hlist_node i_list
; /* list of marks by inode->i_fsnotify_marks */
205 struct list_head free_i_list
; /* tmp list used when freeing this mark */
209 * Mount point specific fields in an fsnotify_mark
211 struct fsnotify_vfsmount_mark
{
212 struct vfsmount
*mnt
; /* vfsmount this mark is associated with */
213 struct hlist_node m_list
; /* list of marks by inode->i_fsnotify_marks */
214 struct list_head free_m_list
; /* tmp list used when freeing this mark */
218 * a mark is simply an object attached to an in core inode which allows an
219 * fsnotify listener to indicate they are either no longer interested in events
220 * of a type matching mask or only interested in those events.
222 * these are flushed when an inode is evicted from core and may be flushed
223 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
224 * (such as dnotify) will flush these when the open fd is closed and not at
225 * inode eviction or modification.
227 struct fsnotify_mark
{
228 __u32 mask
; /* mask this mark is for */
229 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
230 * in kernel that found and may be using this mark. */
231 atomic_t refcnt
; /* active things looking at this mark */
232 struct fsnotify_group
*group
; /* group this mark is for */
233 struct list_head g_list
; /* list of marks by group->i_fsnotify_marks */
234 spinlock_t lock
; /* protect group and inode */
236 struct fsnotify_inode_mark i
;
237 struct fsnotify_vfsmount_mark m
;
239 __u32 ignored_mask
; /* events types to ignore */
240 #define FSNOTIFY_MARK_FLAG_INODE 0x01
241 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
242 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
243 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
244 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10
245 unsigned int flags
; /* vfsmount or inode mark? */
246 struct list_head destroy_list
;
247 void (*free_mark
)(struct fsnotify_mark
*mark
); /* called on final put+free */
250 #ifdef CONFIG_FSNOTIFY
252 /* called from the vfs helpers */
254 /* main fsnotify call to send events */
255 extern int fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
256 const unsigned char *name
, u32 cookie
);
257 extern int __fsnotify_parent(struct path
*path
, struct dentry
*dentry
, __u32 mask
);
258 extern void __fsnotify_inode_delete(struct inode
*inode
);
259 extern void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
);
260 extern u32
fsnotify_get_cookie(void);
262 static inline int fsnotify_inode_watches_children(struct inode
*inode
)
264 /* FS_EVENT_ON_CHILD is set if the inode may care */
265 if (!(inode
->i_fsnotify_mask
& FS_EVENT_ON_CHILD
))
267 /* this inode might care about child events, does it care about the
268 * specific set of events that can happen on a child? */
269 return inode
->i_fsnotify_mask
& FS_EVENTS_POSS_ON_CHILD
;
273 * Update the dentry with a flag indicating the interest of its parent to receive
274 * filesystem events when those events happens to this dentry->d_inode.
276 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
278 struct dentry
*parent
;
280 assert_spin_locked(&dentry
->d_lock
);
283 * Serialisation of setting PARENT_WATCHED on the dentries is provided
284 * by d_lock. If inotify_inode_watched changes after we have taken
285 * d_lock, the following __fsnotify_update_child_dentry_flags call will
286 * find our entry, so it will spin until we complete here, and update
287 * us with the new state.
289 parent
= dentry
->d_parent
;
290 if (parent
->d_inode
&& fsnotify_inode_watches_children(parent
->d_inode
))
291 dentry
->d_flags
|= DCACHE_FSNOTIFY_PARENT_WATCHED
;
293 dentry
->d_flags
&= ~DCACHE_FSNOTIFY_PARENT_WATCHED
;
297 * fsnotify_d_instantiate - instantiate a dentry for inode
299 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
304 spin_lock(&dentry
->d_lock
);
305 __fsnotify_update_dcache_flags(dentry
);
306 spin_unlock(&dentry
->d_lock
);
309 /* called from fsnotify listeners, such as fanotify or dnotify */
311 /* create a new group */
312 extern struct fsnotify_group
*fsnotify_alloc_group(const struct fsnotify_ops
*ops
);
313 /* get reference to a group */
314 extern void fsnotify_get_group(struct fsnotify_group
*group
);
315 /* drop reference on a group from fsnotify_alloc_group */
316 extern void fsnotify_put_group(struct fsnotify_group
*group
);
318 extern void fsnotify_destroy_group(struct fsnotify_group
*group
);
319 /* fasync handler function */
320 extern int fsnotify_fasync(int fd
, struct file
*file
, int on
);
321 /* Free event from memory */
322 extern void fsnotify_destroy_event(struct fsnotify_group
*group
,
323 struct fsnotify_event
*event
);
324 /* attach the event to the group notification queue */
325 extern int fsnotify_add_notify_event(struct fsnotify_group
*group
,
326 struct fsnotify_event
*event
,
327 int (*merge
)(struct list_head
*,
328 struct fsnotify_event
*));
329 /* true if the group notification queue is empty */
330 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group
*group
);
331 /* return, but do not dequeue the first event on the notification queue */
332 extern struct fsnotify_event
*fsnotify_peek_notify_event(struct fsnotify_group
*group
);
333 /* return AND dequeue the first event on the notification queue */
334 extern struct fsnotify_event
*fsnotify_remove_notify_event(struct fsnotify_group
*group
);
336 /* functions used to manipulate the marks attached to inodes */
338 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
339 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount
*mnt
);
340 /* run all marks associated with an inode and update inode->i_fsnotify_mask */
341 extern void fsnotify_recalc_inode_mask(struct inode
*inode
);
342 extern void fsnotify_init_mark(struct fsnotify_mark
*mark
, void (*free_mark
)(struct fsnotify_mark
*mark
));
343 /* find (and take a reference) to a mark associated with group and inode */
344 extern struct fsnotify_mark
*fsnotify_find_inode_mark(struct fsnotify_group
*group
, struct inode
*inode
);
345 /* find (and take a reference) to a mark associated with group and vfsmount */
346 extern struct fsnotify_mark
*fsnotify_find_vfsmount_mark(struct fsnotify_group
*group
, struct vfsmount
*mnt
);
347 /* copy the values from old into new */
348 extern void fsnotify_duplicate_mark(struct fsnotify_mark
*new, struct fsnotify_mark
*old
);
349 /* set the ignored_mask of a mark */
350 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark
*mark
, __u32 mask
);
351 /* set the mask of a mark (might pin the object into memory */
352 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark
*mark
, __u32 mask
);
353 /* attach the mark to both the group and the inode */
354 extern int fsnotify_add_mark(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
,
355 struct inode
*inode
, struct vfsmount
*mnt
, int allow_dups
);
356 extern int fsnotify_add_mark_locked(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
,
357 struct inode
*inode
, struct vfsmount
*mnt
, int allow_dups
);
358 /* given a group and a mark, flag mark to be freed when all references are dropped */
359 extern void fsnotify_destroy_mark(struct fsnotify_mark
*mark
,
360 struct fsnotify_group
*group
);
361 extern void fsnotify_destroy_mark_locked(struct fsnotify_mark
*mark
,
362 struct fsnotify_group
*group
);
363 /* run all the marks in a group, and clear all of the vfsmount marks */
364 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group
*group
);
365 /* run all the marks in a group, and clear all of the inode marks */
366 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group
*group
);
367 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
368 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group
*group
, unsigned int flags
);
369 /* run all the marks in a group, and flag them to be freed */
370 extern void fsnotify_clear_marks_by_group(struct fsnotify_group
*group
);
371 extern void fsnotify_get_mark(struct fsnotify_mark
*mark
);
372 extern void fsnotify_put_mark(struct fsnotify_mark
*mark
);
373 extern void fsnotify_unmount_inodes(struct list_head
*list
);
375 /* put here because inotify does some weird stuff when destroying watches */
376 extern void fsnotify_init_event(struct fsnotify_event
*event
,
377 struct inode
*to_tell
, u32 mask
);
381 static inline int fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
382 const unsigned char *name
, u32 cookie
)
387 static inline int __fsnotify_parent(struct path
*path
, struct dentry
*dentry
, __u32 mask
)
392 static inline void __fsnotify_inode_delete(struct inode
*inode
)
395 static inline void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
)
398 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
401 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
404 static inline u32
fsnotify_get_cookie(void)
409 static inline void fsnotify_unmount_inodes(struct list_head
*list
)
412 #endif /* CONFIG_FSNOTIFY */
414 #endif /* __KERNEL __ */
416 #endif /* __LINUX_FSNOTIFY_BACKEND_H */