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>
19 #include <linux/user_namespace.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_OPEN_PERM 0x00010000 /* open event in an permission hook */
45 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
47 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
48 #define FS_ISDIR 0x40000000 /* event occurred against dir */
49 #define FS_IN_ONESHOT 0x80000000 /* only send event once */
51 #define FS_DN_RENAME 0x10000000 /* file renamed */
52 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
54 /* This inode cares about things that happen to its children. Always set for
55 * dnotify and inotify. */
56 #define FS_EVENT_ON_CHILD 0x08000000
58 /* This is a list of all events that may get sent to a parernt based on fs event
59 * happening to inodes inside that directory */
60 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
61 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
62 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
63 FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)
65 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
67 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
69 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
70 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
71 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
72 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
73 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
74 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
75 FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
76 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
78 struct fsnotify_group;
79 struct fsnotify_event;
81 struct fsnotify_event_private_data;
82 struct fsnotify_fname;
83 struct fsnotify_iter_info;
86 * Each group much define these ops. The fsnotify infrastructure will call
87 * these operations for each relevant group.
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, const void *data, int data_type,
102 const unsigned char *file_name, u32 cookie,
103 struct fsnotify_iter_info *iter_info);
104 void (*free_group_priv)(struct fsnotify_group *group);
105 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
106 void (*free_event)(struct fsnotify_event *event);
110 * all of the information about the original object we want to now send to
111 * a group. If you want to carry more info from the accessing task to the
112 * listener this structure is where you need to be adding fields.
114 struct fsnotify_event {
115 struct list_head list;
116 /* inode may ONLY be dereferenced during handle_event(). */
117 struct inode *inode; /* either the inode the event happened to or its parent */
118 u32 mask; /* the type of access, bitwise OR for FS_* event types */
122 * A group is a "thing" that wants to receive notification about filesystem
123 * events. The mask holds the subset of event types this group cares about.
124 * refcnt on a group is up to the implementor and at any moment if it goes 0
125 * everything will be cleaned up.
127 struct fsnotify_group {
129 * How the refcnt is used is up to each group. When the refcnt hits 0
130 * fsnotify will clean up all of the resources associated with this group.
131 * As an example, the dnotify group will always have a refcnt=1 and that
132 * will never change. Inotify, on the other hand, has a group per
133 * inotify_init() and the refcnt will hit 0 only when that fd has been
136 atomic_t refcnt; /* things with interest in this group */
138 const struct fsnotify_ops *ops; /* how this group handles things */
140 /* needed to send notification to userspace */
141 spinlock_t notification_lock; /* protect the notification_list */
142 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
143 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
144 unsigned int q_len; /* events on the queue */
145 unsigned int max_events; /* maximum events allowed on the list */
147 * Valid fsnotify group priorities. Events are send in order from highest
148 * priority to lowest priority. We default to the lowest priority.
150 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
151 #define FS_PRIO_1 1 /* fanotify content based access control */
152 #define FS_PRIO_2 2 /* fanotify pre-content access */
153 unsigned int priority;
154 bool shutdown; /* group is being shut down, don't queue more events */
156 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
157 struct mutex mark_mutex; /* protect marks_list */
158 atomic_t num_marks; /* 1 for each mark and 1 for not being
159 * past the point of no return when freeing
161 struct list_head marks_list; /* all inode marks for this group */
163 struct fasync_struct *fsn_fa; /* async notification */
165 struct fsnotify_event *overflow_event; /* Event we queue when the
166 * notification list is too
168 atomic_t user_waits; /* Number of tasks waiting for user
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 ucounts *ucounts;
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 list_head access_list;
186 wait_queue_head_t access_waitq;
187 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
189 unsigned int max_marks;
190 struct user_struct *user;
192 #endif /* CONFIG_FANOTIFY */
196 /* when calling fsnotify tell it if the data is a path or inode */
197 #define FSNOTIFY_EVENT_NONE 0
198 #define FSNOTIFY_EVENT_PATH 1
199 #define FSNOTIFY_EVENT_INODE 2
202 * Inode / vfsmount point to this structure which tracks all marks attached to
203 * the inode / vfsmount. The reference to inode / vfsmount is held by this
204 * structure. We destroy this structure when there are no more marks attached
205 * to it. The structure is protected by fsnotify_mark_srcu.
207 struct fsnotify_mark_connector {
209 #define FSNOTIFY_OBJ_TYPE_INODE 0x01
210 #define FSNOTIFY_OBJ_TYPE_VFSMOUNT 0x02
211 unsigned int flags; /* Type of object [lock] */
212 union { /* Object pointer [lock] */
214 struct vfsmount *mnt;
217 struct hlist_head list;
218 /* Used listing heads to free after srcu period expires */
219 struct fsnotify_mark_connector *destroy_next;
224 * A mark is simply an object attached to an in core inode which allows an
225 * fsnotify listener to indicate they are either no longer interested in events
226 * of a type matching mask or only interested in those events.
228 * These are flushed when an inode is evicted from core and may be flushed
229 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
230 * users (such as dnotify) will flush these when the open fd is closed and not
231 * at inode eviction or modification.
233 * Text in brackets is showing the lock(s) protecting modifications of a
234 * particular entry. obj_lock means either inode->i_lock or
235 * mnt->mnt_root->d_lock depending on the mark type.
237 struct fsnotify_mark {
238 /* Mask this mark is for [mark->lock, group->mark_mutex] */
240 /* We hold one for presence in g_list. Also one ref for each 'thing'
241 * in kernel that found and may be using this mark. */
243 /* Group this mark is for. Set on mark creation, stable until last ref
245 struct fsnotify_group *group;
246 /* List of marks by group->i_fsnotify_marks. Also reused for queueing
247 * mark into destroy_list when it's waiting for the end of SRCU period
248 * before it can be freed. [group->mark_mutex] */
249 struct list_head g_list;
250 /* Protects inode / mnt pointers, flags, masks */
252 /* List of marks for inode / vfsmount [connector->lock, mark ref] */
253 struct hlist_node obj_list;
254 /* Head of list of marks for an object [mark ref] */
255 struct fsnotify_mark_connector *connector;
256 /* Events types to ignore [mark->lock, group->mark_mutex] */
258 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x01
259 #define FSNOTIFY_MARK_FLAG_ALIVE 0x02
260 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x04
261 unsigned int flags; /* flags [mark->lock] */
262 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
265 #ifdef CONFIG_FSNOTIFY
267 /* called from the vfs helpers */
269 /* main fsnotify call to send events */
270 extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
271 const unsigned char *name, u32 cookie);
272 extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask);
273 extern void __fsnotify_inode_delete(struct inode *inode);
274 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
275 extern u32 fsnotify_get_cookie(void);
277 static inline int fsnotify_inode_watches_children(struct inode *inode)
279 /* FS_EVENT_ON_CHILD is set if the inode may care */
280 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
282 /* this inode might care about child events, does it care about the
283 * specific set of events that can happen on a child? */
284 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
288 * Update the dentry with a flag indicating the interest of its parent to receive
289 * filesystem events when those events happens to this dentry->d_inode.
291 static inline void fsnotify_update_flags(struct dentry *dentry)
293 assert_spin_locked(&dentry->d_lock);
296 * Serialisation of setting PARENT_WATCHED on the dentries is provided
297 * by d_lock. If inotify_inode_watched changes after we have taken
298 * d_lock, the following __fsnotify_update_child_dentry_flags call will
299 * find our entry, so it will spin until we complete here, and update
300 * us with the new state.
302 if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
303 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
305 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
308 /* called from fsnotify listeners, such as fanotify or dnotify */
310 /* create a new group */
311 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
312 /* get reference to a group */
313 extern void fsnotify_get_group(struct fsnotify_group *group);
314 /* drop reference on a group from fsnotify_alloc_group */
315 extern void fsnotify_put_group(struct fsnotify_group *group);
316 /* group destruction begins, stop queuing new events */
317 extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
319 extern void fsnotify_destroy_group(struct fsnotify_group *group);
320 /* fasync handler function */
321 extern int fsnotify_fasync(int fd, struct file *file, int on);
322 /* Free event from memory */
323 extern void fsnotify_destroy_event(struct fsnotify_group *group,
324 struct fsnotify_event *event);
325 /* attach the event to the group notification queue */
326 extern int fsnotify_add_event(struct fsnotify_group *group,
327 struct fsnotify_event *event,
328 int (*merge)(struct list_head *,
329 struct fsnotify_event *));
330 /* true if the group notification queue is empty */
331 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
332 /* return, but do not dequeue the first event on the notification queue */
333 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
334 /* return AND dequeue the first event on the notification queue */
335 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
337 /* functions used to manipulate the marks attached to inodes */
339 /* Calculate mask of events for a list of marks */
340 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
341 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
342 /* find (and take a reference) to a mark associated with group and inode */
343 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
344 /* find (and take a reference) to a mark associated with group and vfsmount */
345 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
346 /* attach the mark to both the group and the inode */
347 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
348 struct inode *inode, struct vfsmount *mnt, int allow_dups);
349 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
350 struct inode *inode, struct vfsmount *mnt, int allow_dups);
351 /* given a group and a mark, flag mark to be freed when all references are dropped */
352 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
353 struct fsnotify_group *group);
354 /* detach mark from inode / mount list, group list, drop inode reference */
355 extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
357 extern void fsnotify_free_mark(struct fsnotify_mark *mark);
358 /* run all the marks in a group, and clear all of the vfsmount marks */
359 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
360 /* run all the marks in a group, and clear all of the inode marks */
361 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
362 /* run all the marks in a group, and clear all of the marks attached to given object type */
363 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
364 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
365 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
366 extern void fsnotify_unmount_inodes(struct super_block *sb);
367 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
368 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
370 /* put here because inotify does some weird stuff when destroying watches */
371 extern void fsnotify_init_event(struct fsnotify_event *event,
372 struct inode *to_tell, u32 mask);
376 static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
377 const unsigned char *name, u32 cookie)
382 static inline int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
387 static inline void __fsnotify_inode_delete(struct inode *inode)
390 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
393 static inline void fsnotify_update_flags(struct dentry *dentry)
396 static inline u32 fsnotify_get_cookie(void)
401 static inline void fsnotify_unmount_inodes(struct super_block *sb)
404 #endif /* CONFIG_FSNOTIFY */
406 #endif /* __KERNEL __ */
408 #endif /* __LINUX_FSNOTIFY_BACKEND_H */