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>
19 #include <asm/atomic.h>
22 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
23 * convert between them. dnotify only needs conversion at watch creation
24 * so no perf loss there. fanotify isn't defined yet, so it can use the
25 * wholes if it needs more events.
27 #define FS_ACCESS 0x00000001 /* File was accessed */
28 #define FS_MODIFY 0x00000002 /* File was modified */
29 #define FS_ATTRIB 0x00000004 /* Metadata changed */
30 #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
31 #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
32 #define FS_OPEN 0x00000020 /* File was opened */
33 #define FS_MOVED_FROM 0x00000040 /* File was moved from X */
34 #define FS_MOVED_TO 0x00000080 /* File was moved to Y */
35 #define FS_CREATE 0x00000100 /* Subfile was created */
36 #define FS_DELETE 0x00000200 /* Subfile was deleted */
37 #define FS_DELETE_SELF 0x00000400 /* Self was deleted */
38 #define FS_MOVE_SELF 0x00000800 /* Self was moved */
40 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */
41 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
42 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */
44 #define FS_IN_ISDIR 0x40000000 /* event occurred against dir */
45 #define FS_IN_ONESHOT 0x80000000 /* only send event once */
47 #define FS_DN_RENAME 0x10000000 /* file renamed */
48 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
50 /* This inode cares about things that happen to its children. Always set for
51 * dnotify and inotify. */
52 #define FS_EVENT_ON_CHILD 0x08000000
54 /* This is a list of all events that may get sent to a parernt based on fs event
55 * happening to inodes inside that directory */
56 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
57 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
58 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
61 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
63 /* listeners that hard code group numbers near the top */
64 #define DNOTIFY_GROUP_NUM UINT_MAX
65 #define AUDIT_WATCH_GROUP_NUM (DNOTIFY_GROUP_NUM-1)
66 #define AUDIT_TREE_GROUP_NUM (AUDIT_WATCH_GROUP_NUM-1)
67 #define INOTIFY_GROUP_NUM (AUDIT_TREE_GROUP_NUM-1)
69 struct fsnotify_group
;
70 struct fsnotify_event
;
71 struct fsnotify_mark_entry
;
72 struct fsnotify_event_private_data
;
75 * Each group much define these ops. The fsnotify infrastructure will call
76 * these operations for each relevant group.
78 * should_send_event - given a group, inode, and mask this function determines
79 * if the group is interested in this event.
80 * handle_event - main call for a group to handle an fs event
81 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
82 * freeing-mark - this means that a mark has been flagged to die when everything
83 * finishes using it. The function is supplied with what must be a
84 * valid group and inode to use to clean up.
87 bool (*should_send_event
)(struct fsnotify_group
*group
, struct inode
*inode
, __u32 mask
);
88 int (*handle_event
)(struct fsnotify_group
*group
, struct fsnotify_event
*event
);
89 void (*free_group_priv
)(struct fsnotify_group
*group
);
90 void (*freeing_mark
)(struct fsnotify_mark_entry
*entry
, struct fsnotify_group
*group
);
91 void (*free_event_priv
)(struct fsnotify_event_private_data
*priv
);
95 * A group is a "thing" that wants to receive notification about filesystem
96 * events. The mask holds the subset of event types this group cares about.
97 * refcnt on a group is up to the implementor and at any moment if it goes 0
98 * everything will be cleaned up.
100 struct fsnotify_group
{
102 * global list of all groups receiving events from fsnotify.
103 * anchored by fsnotify_groups and protected by either fsnotify_grp_mutex
104 * or fsnotify_grp_srcu depending on write vs read.
106 struct list_head group_list
;
109 * Defines all of the event types in which this group is interested.
110 * This mask is a bitwise OR of the FS_* events from above. Each time
111 * this mask changes for a group (if it changes) the correct functions
112 * must be called to update the global structures which indicate global
113 * interest in event types.
118 * How the refcnt is used is up to each group. When the refcnt hits 0
119 * fsnotify will clean up all of the resources associated with this group.
120 * As an example, the dnotify group will always have a refcnt=1 and that
121 * will never change. Inotify, on the other hand, has a group per
122 * inotify_init() and the refcnt will hit 0 only when that fd has been
125 atomic_t refcnt
; /* things with interest in this group */
126 unsigned int group_num
; /* simply prevents accidental group collision */
128 const struct fsnotify_ops
*ops
; /* how this group handles things */
130 /* needed to send notification to userspace */
131 struct mutex notification_mutex
; /* protect the notification_list */
132 struct list_head notification_list
; /* list of event_holder this group needs to send to userspace */
133 wait_queue_head_t notification_waitq
; /* read() on the notification file blocks on this waitq */
134 unsigned int q_len
; /* events on the queue */
135 unsigned int max_events
; /* maximum events allowed on the list */
137 /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */
138 spinlock_t mark_lock
; /* protect mark_entries list */
139 atomic_t num_marks
; /* 1 for each mark entry and 1 for not being
140 * past the point of no return when freeing
142 struct list_head mark_entries
; /* all inode mark entries for this group */
144 /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */
147 /* groups can define private fields here or use the void *private */
150 #ifdef CONFIG_INOTIFY_USER
151 struct inotify_group_private_data
{
155 struct fasync_struct
*fa
; /* async notification */
156 struct user_struct
*user
;
163 * A single event can be queued in multiple group->notification_lists.
165 * each group->notification_list will point to an event_holder which in turns points
166 * to the actual event that needs to be sent to userspace.
168 * Seemed cheaper to create a refcnt'd event and a small holder for every group
169 * than create a different event for every group
172 struct fsnotify_event_holder
{
173 struct fsnotify_event
*event
;
174 struct list_head event_list
;
178 * Inotify needs to tack data onto an event. This struct lets us later find the
179 * correct private data of the correct group.
181 struct fsnotify_event_private_data
{
182 struct fsnotify_group
*group
;
183 struct list_head event_list
;
187 * all of the information about the original object we want to now send to
188 * a group. If you want to carry more info from the accessing task to the
189 * listener this structure is where you need to be adding fields.
191 struct fsnotify_event
{
193 * If we create an event we are also likely going to need a holder
194 * to link to a group. So embed one holder in the event. Means only
195 * one allocation for the common case where we only have one group
197 struct fsnotify_event_holder holder
;
198 spinlock_t lock
; /* protection for the associated event_holder and private_list */
199 /* to_tell may ONLY be dereferenced during handle_event(). */
200 struct inode
*to_tell
; /* either the inode the event happened to or its parent */
202 * depending on the event type we should have either a path or inode
203 * We hold a reference on path, but NOT on inode. Since we have the ref on
204 * the path, it may be dereferenced at any point during this object's
205 * lifetime. That reference is dropped when this object's refcnt hits
206 * 0. If this event contains an inode instead of a path, the inode may
207 * ONLY be used during handle_event().
213 /* when calling fsnotify tell it if the data is a path or inode */
214 #define FSNOTIFY_EVENT_NONE 0
215 #define FSNOTIFY_EVENT_PATH 1
216 #define FSNOTIFY_EVENT_INODE 2
217 #define FSNOTIFY_EVENT_FILE 3
218 int data_type
; /* which of the above union we have */
219 atomic_t refcnt
; /* how many groups still are using/need to send this event */
220 __u32 mask
; /* the type of access, bitwise OR for FS_* event types */
222 u32 sync_cookie
; /* used to corrolate events, namely inotify mv events */
226 struct list_head private_data_list
; /* groups can store private data here */
230 * a mark is simply an entry attached to an in core inode which allows an
231 * fsnotify listener to indicate they are either no longer interested in events
232 * of a type matching mask or only interested in those events.
234 * these are flushed when an inode is evicted from core and may be flushed
235 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
236 * (such as dnotify) will flush these when the open fd is closed and not at
237 * inode eviction or modification.
239 struct fsnotify_mark_entry
{
240 __u32 mask
; /* mask this mark entry is for */
241 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
242 * in kernel that found and may be using this mark. */
243 atomic_t refcnt
; /* active things looking at this mark */
244 struct inode
*inode
; /* inode this entry is associated with */
245 struct fsnotify_group
*group
; /* group this mark entry is for */
246 struct hlist_node i_list
; /* list of mark_entries by inode->i_fsnotify_mark_entries */
247 struct list_head g_list
; /* list of mark_entries by group->i_fsnotify_mark_entries */
248 spinlock_t lock
; /* protect group, inode, and killme */
249 struct list_head free_i_list
; /* tmp list used when freeing this mark */
250 struct list_head free_g_list
; /* tmp list used when freeing this mark */
251 void (*free_mark
)(struct fsnotify_mark_entry
*entry
); /* called on final put+free */
254 #ifdef CONFIG_FSNOTIFY
256 /* called from the vfs helpers */
258 /* main fsnotify call to send events */
259 extern void fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
260 const char *name
, u32 cookie
);
261 extern void __fsnotify_parent(struct dentry
*dentry
, __u32 mask
);
262 extern void __fsnotify_inode_delete(struct inode
*inode
);
263 extern u32
fsnotify_get_cookie(void);
265 static inline int fsnotify_inode_watches_children(struct inode
*inode
)
267 /* FS_EVENT_ON_CHILD is set if the inode may care */
268 if (!(inode
->i_fsnotify_mask
& FS_EVENT_ON_CHILD
))
270 /* this inode might care about child events, does it care about the
271 * specific set of events that can happen on a child? */
272 return inode
->i_fsnotify_mask
& FS_EVENTS_POSS_ON_CHILD
;
276 * Update the dentry with a flag indicating the interest of its parent to receive
277 * filesystem events when those events happens to this dentry->d_inode.
279 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
281 struct dentry
*parent
;
283 assert_spin_locked(&dcache_lock
);
284 assert_spin_locked(&dentry
->d_lock
);
286 parent
= dentry
->d_parent
;
287 if (parent
->d_inode
&& fsnotify_inode_watches_children(parent
->d_inode
))
288 dentry
->d_flags
|= DCACHE_FSNOTIFY_PARENT_WATCHED
;
290 dentry
->d_flags
&= ~DCACHE_FSNOTIFY_PARENT_WATCHED
;
294 * fsnotify_d_instantiate - instantiate a dentry for inode
295 * Called with dcache_lock held.
297 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
302 assert_spin_locked(&dcache_lock
);
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 /* must call when a group changes its ->mask */
312 extern void fsnotify_recalc_global_mask(void);
313 /* get a reference to an existing or create a new group */
314 extern struct fsnotify_group
*fsnotify_obtain_group(unsigned int group_num
,
316 const struct fsnotify_ops
*ops
);
317 /* run all marks associated with this group and update group->mask */
318 extern void fsnotify_recalc_group_mask(struct fsnotify_group
*group
);
319 /* drop reference on a group from fsnotify_obtain_group */
320 extern void fsnotify_put_group(struct fsnotify_group
*group
);
322 /* take a reference to an event */
323 extern void fsnotify_get_event(struct fsnotify_event
*event
);
324 extern void fsnotify_put_event(struct fsnotify_event
*event
);
325 /* find private data previously attached to an event and unlink it */
326 extern struct fsnotify_event_private_data
*fsnotify_remove_priv_from_event(struct fsnotify_group
*group
,
327 struct fsnotify_event
*event
);
329 /* attach the event to the group notification queue */
330 extern int fsnotify_add_notify_event(struct fsnotify_group
*group
, struct fsnotify_event
*event
,
331 struct fsnotify_event_private_data
*priv
);
332 /* true if the group notification queue is empty */
333 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group
*group
);
334 /* return, but do not dequeue the first event on the notification queue */
335 extern struct fsnotify_event
*fsnotify_peek_notify_event(struct fsnotify_group
*group
);
336 /* return AND dequeue the first event on the notification queue */
337 extern struct fsnotify_event
*fsnotify_remove_notify_event(struct fsnotify_group
*group
);
339 /* functions used to manipulate the marks attached to inodes */
341 /* run all marks associated with an inode and update inode->i_fsnotify_mask */
342 extern void fsnotify_recalc_inode_mask(struct inode
*inode
);
343 extern void fsnotify_init_mark(struct fsnotify_mark_entry
*entry
, void (*free_mark
)(struct fsnotify_mark_entry
*entry
));
344 /* find (and take a reference) to a mark associated with group and inode */
345 extern struct fsnotify_mark_entry
*fsnotify_find_mark_entry(struct fsnotify_group
*group
, struct inode
*inode
);
346 /* copy the values from old into new */
347 extern void fsnotify_duplicate_mark(struct fsnotify_mark_entry
*new, struct fsnotify_mark_entry
*old
);
348 /* attach the mark to both the group and the inode */
349 extern int fsnotify_add_mark(struct fsnotify_mark_entry
*entry
, struct fsnotify_group
*group
, struct inode
*inode
, int allow_dups
);
350 /* given a mark, flag it to be freed when all references are dropped */
351 extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry
*entry
);
352 /* run all the marks in a group, and flag them to be freed */
353 extern void fsnotify_clear_marks_by_group(struct fsnotify_group
*group
);
354 extern void fsnotify_get_mark(struct fsnotify_mark_entry
*entry
);
355 extern void fsnotify_put_mark(struct fsnotify_mark_entry
*entry
);
356 extern void fsnotify_unmount_inodes(struct list_head
*list
);
358 /* put here because inotify does some weird stuff when destroying watches */
359 extern struct fsnotify_event
*fsnotify_create_event(struct inode
*to_tell
, __u32 mask
,
360 void *data
, int data_is
, const char *name
,
361 u32 cookie
, gfp_t gfp
);
365 static inline void fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
366 const char *name
, u32 cookie
)
369 static inline void __fsnotify_parent(struct dentry
*dentry
, __u32 mask
)
372 static inline void __fsnotify_inode_delete(struct inode
*inode
)
375 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
378 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
381 static inline u32
fsnotify_get_cookie(void)
386 static inline void fsnotify_unmount_inodes(struct list_head
*list
)
389 #endif /* CONFIG_FSNOTIFY */
391 #endif /* __KERNEL __ */
393 #endif /* __LINUX_FSNOTIFY_BACKEND_H */