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_OPEN_PERM 0x00010000 /* open event in an permission hook */
45 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
47 #define FS_IN_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 |\
64 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
66 struct fsnotify_group;
67 struct fsnotify_event;
69 struct fsnotify_event_private_data;
72 * Each group much define these ops. The fsnotify infrastructure will call
73 * these operations for each relevant group.
75 * should_send_event - given a group, inode, and mask this function determines
76 * if the group is interested in this event.
77 * handle_event - main call for a group to handle an fs event
78 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
79 * freeing-mark - this means that a mark has been flagged to die when everything
80 * finishes using it. The function is supplied with what must be a
81 * valid group and inode to use to clean up.
84 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode,
85 struct vfsmount *mnt, __u32 mask, void *data,
87 int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event);
88 void (*free_group_priv)(struct fsnotify_group *group);
89 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
90 void (*free_event_priv)(struct fsnotify_event_private_data *priv);
94 * A group is a "thing" that wants to receive notification about filesystem
95 * events. The mask holds the subset of event types this group cares about.
96 * refcnt on a group is up to the implementor and at any moment if it goes 0
97 * everything will be cleaned up.
99 struct fsnotify_group {
101 * global list of all groups receiving events from fsnotify.
102 * anchored by fsnotify_inode_groups and protected by either fsnotify_grp_mutex
103 * or fsnotify_grp_srcu depending on write vs read.
105 struct list_head inode_group_list;
107 * same as above except anchored by fsnotify_vfsmount_groups
109 struct list_head vfsmount_group_list;
112 * Defines all of the event types in which this group is interested.
113 * This mask is a bitwise OR of the FS_* events from above. Each time
114 * this mask changes for a group (if it changes) the correct functions
115 * must be called to update the global structures which indicate global
116 * interest in event types.
121 * How the refcnt is used is up to each group. When the refcnt hits 0
122 * fsnotify will clean up all of the resources associated with this group.
123 * As an example, the dnotify group will always have a refcnt=1 and that
124 * will never change. Inotify, on the other hand, has a group per
125 * inotify_init() and the refcnt will hit 0 only when that fd has been
128 atomic_t refcnt; /* things with interest in this group */
130 const struct fsnotify_ops *ops; /* how this group handles things */
132 /* needed to send notification to userspace */
133 struct mutex notification_mutex; /* protect the notification_list */
134 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
135 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
136 unsigned int q_len; /* events on the queue */
137 unsigned int max_events; /* maximum events allowed on the list */
139 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
140 spinlock_t mark_lock; /* protect marks_list */
141 atomic_t num_marks; /* 1 for each mark and 1 for not being
142 * past the point of no return when freeing
144 struct list_head marks_list; /* all inode marks for this group */
146 unsigned int priority; /* order of this group compared to others */
147 /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */
148 bool on_inode_group_list;
149 bool on_vfsmount_group_list;
151 /* groups can define private fields here or use the void *private */
154 #ifdef CONFIG_INOTIFY_USER
155 struct inotify_group_private_data {
159 struct fasync_struct *fa; /* async notification */
160 struct user_struct *user;
167 * A single event can be queued in multiple group->notification_lists.
169 * each group->notification_list will point to an event_holder which in turns points
170 * to the actual event that needs to be sent to userspace.
172 * Seemed cheaper to create a refcnt'd event and a small holder for every group
173 * than create a different event for every group
176 struct fsnotify_event_holder {
177 struct fsnotify_event *event;
178 struct list_head event_list;
182 * Inotify needs to tack data onto an event. This struct lets us later find the
183 * correct private data of the correct group.
185 struct fsnotify_event_private_data {
186 struct fsnotify_group *group;
187 struct list_head event_list;
191 * all of the information about the original object we want to now send to
192 * a group. If you want to carry more info from the accessing task to the
193 * listener this structure is where you need to be adding fields.
195 struct fsnotify_event {
197 * If we create an event we are also likely going to need a holder
198 * to link to a group. So embed one holder in the event. Means only
199 * one allocation for the common case where we only have one group
201 struct fsnotify_event_holder holder;
202 spinlock_t lock; /* protection for the associated event_holder and private_list */
203 /* to_tell may ONLY be dereferenced during handle_event(). */
204 struct inode *to_tell; /* either the inode the event happened to or its parent */
206 * depending on the event type we should have either a path or inode
207 * We hold a reference on path, but NOT on inode. Since we have the ref on
208 * the path, it may be dereferenced at any point during this object's
209 * lifetime. That reference is dropped when this object's refcnt hits
210 * 0. If this event contains an inode instead of a path, the inode may
211 * ONLY be used during handle_event().
217 /* when calling fsnotify tell it if the data is a path or inode */
218 #define FSNOTIFY_EVENT_NONE 0
219 #define FSNOTIFY_EVENT_PATH 1
220 #define FSNOTIFY_EVENT_INODE 2
221 int data_type; /* which of the above union we have */
222 atomic_t refcnt; /* how many groups still are using/need to send this event */
223 __u32 mask; /* the type of access, bitwise OR for FS_* event types */
225 u32 sync_cookie; /* used to corrolate events, namely inotify mv events */
226 const unsigned char *file_name;
230 struct list_head private_data_list; /* groups can store private data here */
234 * Inode specific fields in an fsnotify_mark
236 struct fsnotify_inode_mark {
237 struct inode *inode; /* inode this mark is associated with */
238 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */
239 struct list_head free_i_list; /* tmp list used when freeing this mark */
243 * Mount point specific fields in an fsnotify_mark
245 struct fsnotify_vfsmount_mark {
246 struct vfsmount *mnt; /* vfsmount this mark is associated with */
247 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */
248 struct list_head free_m_list; /* tmp list used when freeing this mark */
252 * a mark is simply an object attached to an in core inode which allows an
253 * fsnotify listener to indicate they are either no longer interested in events
254 * of a type matching mask or only interested in those events.
256 * these are flushed when an inode is evicted from core and may be flushed
257 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
258 * (such as dnotify) will flush these when the open fd is closed and not at
259 * inode eviction or modification.
261 struct fsnotify_mark {
262 __u32 mask; /* mask this mark is for */
263 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
264 * in kernel that found and may be using this mark. */
265 atomic_t refcnt; /* active things looking at this mark */
266 struct fsnotify_group *group; /* group this mark is for */
267 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */
268 spinlock_t lock; /* protect group and inode */
270 struct fsnotify_inode_mark i;
271 struct fsnotify_vfsmount_mark m;
273 __u32 ignored_mask; /* events types to ignore */
274 struct list_head free_g_list; /* tmp list used when freeing this mark */
275 #define FSNOTIFY_MARK_FLAG_INODE 0x01
276 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
277 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
278 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
279 unsigned int flags; /* vfsmount or inode mark? */
280 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
283 #ifdef CONFIG_FSNOTIFY
285 /* called from the vfs helpers */
287 /* main fsnotify call to send events */
288 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
289 const unsigned char *name, u32 cookie);
290 extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
291 extern void __fsnotify_inode_delete(struct inode *inode);
292 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
293 extern u32 fsnotify_get_cookie(void);
295 static inline int fsnotify_inode_watches_children(struct inode *inode)
297 /* FS_EVENT_ON_CHILD is set if the inode may care */
298 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
300 /* this inode might care about child events, does it care about the
301 * specific set of events that can happen on a child? */
302 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
306 * Update the dentry with a flag indicating the interest of its parent to receive
307 * filesystem events when those events happens to this dentry->d_inode.
309 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
311 struct dentry *parent;
313 assert_spin_locked(&dcache_lock);
314 assert_spin_locked(&dentry->d_lock);
316 parent = dentry->d_parent;
317 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
318 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
320 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
324 * fsnotify_d_instantiate - instantiate a dentry for inode
325 * Called with dcache_lock held.
327 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
332 assert_spin_locked(&dcache_lock);
334 spin_lock(&dentry->d_lock);
335 __fsnotify_update_dcache_flags(dentry);
336 spin_unlock(&dentry->d_lock);
339 /* called from fsnotify listeners, such as fanotify or dnotify */
341 /* must call when a group changes its ->mask */
342 extern void fsnotify_recalc_global_mask(void);
343 /* get a reference to an existing or create a new group */
344 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
345 /* run all marks associated with this group and update group->mask */
346 extern void fsnotify_recalc_group_mask(struct fsnotify_group *group);
347 /* drop reference on a group from fsnotify_alloc_group */
348 extern void fsnotify_put_group(struct fsnotify_group *group);
350 /* take a reference to an event */
351 extern void fsnotify_get_event(struct fsnotify_event *event);
352 extern void fsnotify_put_event(struct fsnotify_event *event);
353 /* find private data previously attached to an event and unlink it */
354 extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group,
355 struct fsnotify_event *event);
357 /* attach the event to the group notification queue */
358 extern int fsnotify_add_notify_event(struct fsnotify_group *group,
359 struct fsnotify_event *event,
360 struct fsnotify_event_private_data *priv,
361 int (*merge)(struct list_head *,
362 struct fsnotify_event *,
365 /* true if the group notification queue is empty */
366 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
367 /* return, but do not dequeue the first event on the notification queue */
368 extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group);
369 /* return AND dequeue the first event on the notification queue */
370 extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group);
372 /* functions used to manipulate the marks attached to inodes */
374 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
375 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
376 /* run all marks associated with an inode and update inode->i_fsnotify_mask */
377 extern void fsnotify_recalc_inode_mask(struct inode *inode);
378 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
379 /* find (and take a reference) to a mark associated with group and inode */
380 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
381 /* find (and take a reference) to a mark associated with group and vfsmount */
382 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
383 /* copy the values from old into new */
384 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
385 /* set the ignored_mask of a mark */
386 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
387 /* set the mask of a mark (might pin the object into memory */
388 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
389 /* attach the mark to both the group and the inode */
390 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
391 struct inode *inode, struct vfsmount *mnt, int allow_dups);
392 /* given a mark, flag it to be freed when all references are dropped */
393 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark);
394 /* run all the marks in a group, and clear all of the vfsmount marks */
395 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
396 /* run all the marks in a group, and clear all of the inode marks */
397 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
398 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
399 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
400 /* run all the marks in a group, and flag them to be freed */
401 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
402 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
403 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
404 extern void fsnotify_unmount_inodes(struct list_head *list);
406 /* put here because inotify does some weird stuff when destroying watches */
407 extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
408 void *data, int data_is,
409 const unsigned char *name,
410 u32 cookie, gfp_t gfp);
412 /* fanotify likes to change events after they are on lists... */
413 extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event);
414 extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder,
415 struct fsnotify_event *new_event);
419 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
420 const unsigned char *name, u32 cookie)
425 static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
428 static inline void __fsnotify_inode_delete(struct inode *inode)
431 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
434 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
437 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
440 static inline u32 fsnotify_get_cookie(void)
445 static inline void fsnotify_unmount_inodes(struct list_head *list)
448 #endif /* CONFIG_FSNOTIFY */
450 #endif /* __KERNEL __ */
452 #endif /* __LINUX_FSNOTIFY_BACKEND_H */