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 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode,
98 struct fsnotify_mark *inode_mark,
99 struct fsnotify_mark *vfsmount_mark,
100 __u32 mask, void *data, int data_type);
101 int (*handle_event)(struct fsnotify_group *group,
103 struct fsnotify_mark *inode_mark,
104 struct fsnotify_mark *vfsmount_mark,
105 u32 mask, void *data, int data_type,
106 const unsigned char *file_name);
107 void (*free_group_priv)(struct fsnotify_group *group);
108 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
109 void (*free_event)(struct fsnotify_event *event);
113 * all of the information about the original object we want to now send to
114 * a group. If you want to carry more info from the accessing task to the
115 * listener this structure is where you need to be adding fields.
117 struct fsnotify_event {
118 struct list_head list;
119 /* inode may ONLY be dereferenced during handle_event(). */
120 struct inode *inode; /* either the inode the event happened to or its parent */
121 u32 mask; /* the type of access, bitwise OR for FS_* event types */
125 * A group is a "thing" that wants to receive notification about filesystem
126 * events. The mask holds the subset of event types this group cares about.
127 * refcnt on a group is up to the implementor and at any moment if it goes 0
128 * everything will be cleaned up.
130 struct fsnotify_group {
132 * How the refcnt is used is up to each group. When the refcnt hits 0
133 * fsnotify will clean up all of the resources associated with this group.
134 * As an example, the dnotify group will always have a refcnt=1 and that
135 * will never change. Inotify, on the other hand, has a group per
136 * inotify_init() and the refcnt will hit 0 only when that fd has been
139 atomic_t refcnt; /* things with interest in this group */
141 const struct fsnotify_ops *ops; /* how this group handles things */
143 /* needed to send notification to userspace */
144 struct mutex notification_mutex; /* protect the notification_list */
145 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
146 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
147 unsigned int q_len; /* events on the queue */
148 unsigned int max_events; /* maximum events allowed on the list */
150 * Valid fsnotify group priorities. Events are send in order from highest
151 * priority to lowest priority. We default to the lowest priority.
153 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
154 #define FS_PRIO_1 1 /* fanotify content based access control */
155 #define FS_PRIO_2 2 /* fanotify pre-content access */
156 unsigned int priority;
158 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
159 struct mutex mark_mutex; /* protect marks_list */
160 atomic_t num_marks; /* 1 for each mark and 1 for not being
161 * past the point of no return when freeing
163 struct list_head marks_list; /* all inode marks for this group */
165 struct fasync_struct *fsn_fa; /* async notification */
167 struct fsnotify_event overflow_event; /* Event we queue when the
168 * notification list is too
171 /* groups can define private fields here or use the void *private */
174 #ifdef CONFIG_INOTIFY_USER
175 struct inotify_group_private_data {
178 struct user_struct *user;
181 #ifdef CONFIG_FANOTIFY
182 struct fanotify_group_private_data {
183 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
184 /* allows a group to block waiting for a userspace response */
185 struct mutex access_mutex;
186 struct list_head access_list;
187 wait_queue_head_t access_waitq;
188 atomic_t bypass_perm;
189 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
191 unsigned int max_marks;
192 struct user_struct *user;
194 #endif /* CONFIG_FANOTIFY */
198 /* when calling fsnotify tell it if the data is a path or inode */
199 #define FSNOTIFY_EVENT_NONE 0
200 #define FSNOTIFY_EVENT_PATH 1
201 #define FSNOTIFY_EVENT_INODE 2
204 * Inode specific fields in an fsnotify_mark
206 struct fsnotify_inode_mark {
207 struct inode *inode; /* inode this mark is associated with */
208 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */
209 struct list_head free_i_list; /* tmp list used when freeing this mark */
213 * Mount point specific fields in an fsnotify_mark
215 struct fsnotify_vfsmount_mark {
216 struct vfsmount *mnt; /* vfsmount this mark is associated with */
217 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */
218 struct list_head free_m_list; /* tmp list used when freeing this mark */
222 * a mark is simply an object attached to an in core inode which allows an
223 * fsnotify listener to indicate they are either no longer interested in events
224 * of a type matching mask or only interested in those events.
226 * these are flushed when an inode is evicted from core and may be flushed
227 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
228 * (such as dnotify) will flush these when the open fd is closed and not at
229 * inode eviction or modification.
231 struct fsnotify_mark {
232 __u32 mask; /* mask this mark is for */
233 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
234 * in kernel that found and may be using this mark. */
235 atomic_t refcnt; /* active things looking at this mark */
236 struct fsnotify_group *group; /* group this mark is for */
237 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */
238 spinlock_t lock; /* protect group and inode */
240 struct fsnotify_inode_mark i;
241 struct fsnotify_vfsmount_mark m;
243 __u32 ignored_mask; /* events types to ignore */
244 #define FSNOTIFY_MARK_FLAG_INODE 0x01
245 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
246 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
247 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
248 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10
249 unsigned int flags; /* vfsmount or inode mark? */
250 struct list_head destroy_list;
251 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
254 #ifdef CONFIG_FSNOTIFY
256 /* called from the vfs helpers */
258 /* main fsnotify call to send events */
259 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
260 const unsigned char *name, u32 cookie);
261 extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
262 extern void __fsnotify_inode_delete(struct inode *inode);
263 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
264 extern u32 fsnotify_get_cookie(void);
266 static inline int fsnotify_inode_watches_children(struct inode *inode)
268 /* FS_EVENT_ON_CHILD is set if the inode may care */
269 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
271 /* this inode might care about child events, does it care about the
272 * specific set of events that can happen on a child? */
273 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
277 * Update the dentry with a flag indicating the interest of its parent to receive
278 * filesystem events when those events happens to this dentry->d_inode.
280 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
282 struct dentry *parent;
284 assert_spin_locked(&dentry->d_lock);
287 * Serialisation of setting PARENT_WATCHED on the dentries is provided
288 * by d_lock. If inotify_inode_watched changes after we have taken
289 * d_lock, the following __fsnotify_update_child_dentry_flags call will
290 * find our entry, so it will spin until we complete here, and update
291 * us with the new state.
293 parent = dentry->d_parent;
294 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
295 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
297 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
301 * fsnotify_d_instantiate - instantiate a dentry for inode
303 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
308 spin_lock(&dentry->d_lock);
309 __fsnotify_update_dcache_flags(dentry);
310 spin_unlock(&dentry->d_lock);
313 /* called from fsnotify listeners, such as fanotify or dnotify */
315 /* create a new group */
316 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
317 /* get reference to a group */
318 extern void fsnotify_get_group(struct fsnotify_group *group);
319 /* drop reference on a group from fsnotify_alloc_group */
320 extern void fsnotify_put_group(struct fsnotify_group *group);
322 extern void fsnotify_destroy_group(struct fsnotify_group *group);
323 /* fasync handler function */
324 extern int fsnotify_fasync(int fd, struct file *file, int on);
325 /* Free event from memory */
326 extern void fsnotify_destroy_event(struct fsnotify_group *group,
327 struct fsnotify_event *event);
328 /* attach the event to the group notification queue */
329 extern struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group,
330 struct fsnotify_event *event,
331 struct fsnotify_event *(*merge)(struct list_head *,
332 struct fsnotify_event *));
333 /* true if the group notification queue is empty */
334 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
335 /* return, but do not dequeue the first event on the notification queue */
336 extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group);
337 /* return AND dequeue the first event on the notification queue */
338 extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group);
340 /* functions used to manipulate the marks attached to inodes */
342 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
343 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
344 /* run all marks associated with an inode and update inode->i_fsnotify_mask */
345 extern void fsnotify_recalc_inode_mask(struct inode *inode);
346 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
347 /* find (and take a reference) to a mark associated with group and inode */
348 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
349 /* find (and take a reference) to a mark associated with group and vfsmount */
350 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
351 /* copy the values from old into new */
352 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
353 /* set the ignored_mask of a mark */
354 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
355 /* set the mask of a mark (might pin the object into memory */
356 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
357 /* attach the mark to both the group and the inode */
358 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
359 struct inode *inode, struct vfsmount *mnt, int allow_dups);
360 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
361 struct inode *inode, struct vfsmount *mnt, int allow_dups);
362 /* given a group and a mark, flag mark to be freed when all references are dropped */
363 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
364 struct fsnotify_group *group);
365 extern void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark,
366 struct fsnotify_group *group);
367 /* run all the marks in a group, and clear all of the vfsmount marks */
368 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
369 /* run all the marks in a group, and clear all of the inode marks */
370 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
371 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
372 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
373 /* run all the marks in a group, and flag them to be freed */
374 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
375 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
376 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
377 extern void fsnotify_unmount_inodes(struct list_head *list);
379 /* put here because inotify does some weird stuff when destroying watches */
380 extern void fsnotify_init_event(struct fsnotify_event *event,
381 struct inode *to_tell, u32 mask);
385 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
386 const unsigned char *name, u32 cookie)
391 static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
396 static inline void __fsnotify_inode_delete(struct inode *inode)
399 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
402 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
405 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
408 static inline u32 fsnotify_get_cookie(void)
413 static inline void fsnotify_unmount_inodes(struct list_head *list)
416 #endif /* CONFIG_FSNOTIFY */
418 #endif /* __KERNEL __ */
420 #endif /* __LINUX_FSNOTIFY_BACKEND_H */