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_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
48 #define FS_IN_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 |\
65 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
67 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
68 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
69 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
70 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
71 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
72 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
73 FS_IN_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
74 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
76 struct fsnotify_group;
77 struct fsnotify_event;
79 struct fsnotify_event_private_data;
82 * Each group much define these ops. The fsnotify infrastructure will call
83 * these operations for each relevant group.
85 * should_send_event - given a group, inode, and mask this function determines
86 * if the group is interested in this event.
87 * handle_event - main call for a group to handle an fs event
88 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
89 * freeing-mark - this means that a mark has been flagged to die when everything
90 * finishes using it. The function is supplied with what must be a
91 * valid group and inode to use to clean up.
94 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode,
95 struct vfsmount *mnt, __u32 mask, void *data,
97 int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event);
98 void (*free_group_priv)(struct fsnotify_group *group);
99 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
100 void (*free_event_priv)(struct fsnotify_event_private_data *priv);
104 * A group is a "thing" that wants to receive notification about filesystem
105 * events. The mask holds the subset of event types this group cares about.
106 * refcnt on a group is up to the implementor and at any moment if it goes 0
107 * everything will be cleaned up.
109 struct fsnotify_group {
111 * global list of all groups receiving events from fsnotify.
112 * anchored by fsnotify_inode_groups and protected by either fsnotify_grp_mutex
113 * or fsnotify_grp_srcu depending on write vs read.
115 struct list_head inode_group_list;
117 * same as above except anchored by fsnotify_vfsmount_groups
119 struct list_head vfsmount_group_list;
122 * Defines all of the event types in which this group is interested.
123 * This mask is a bitwise OR of the FS_* events from above. Each time
124 * this mask changes for a group (if it changes) the correct functions
125 * must be called to update the global structures which indicate global
126 * interest in event types.
131 * How the refcnt is used is up to each group. When the refcnt hits 0
132 * fsnotify will clean up all of the resources associated with this group.
133 * As an example, the dnotify group will always have a refcnt=1 and that
134 * will never change. Inotify, on the other hand, has a group per
135 * inotify_init() and the refcnt will hit 0 only when that fd has been
138 atomic_t refcnt; /* things with interest in this group */
140 const struct fsnotify_ops *ops; /* how this group handles things */
142 /* needed to send notification to userspace */
143 struct mutex notification_mutex; /* protect the notification_list */
144 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
145 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
146 unsigned int q_len; /* events on the queue */
147 unsigned int max_events; /* maximum events allowed on the list */
149 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
150 spinlock_t mark_lock; /* protect marks_list */
151 atomic_t num_marks; /* 1 for each mark and 1 for not being
152 * past the point of no return when freeing
154 struct list_head marks_list; /* all inode marks for this group */
156 /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */
157 bool on_inode_group_list;
158 bool on_vfsmount_group_list;
160 /* groups can define private fields here or use the void *private */
163 #ifdef CONFIG_INOTIFY_USER
164 struct inotify_group_private_data {
168 struct fasync_struct *fa; /* async notification */
169 struct user_struct *user;
172 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
173 struct fanotify_group_private_data {
174 /* allows a group to block waiting for a userspace response */
175 struct mutex access_mutex;
176 struct list_head access_list;
177 wait_queue_head_t access_waitq;
184 * A single event can be queued in multiple group->notification_lists.
186 * each group->notification_list will point to an event_holder which in turns points
187 * to the actual event that needs to be sent to userspace.
189 * Seemed cheaper to create a refcnt'd event and a small holder for every group
190 * than create a different event for every group
193 struct fsnotify_event_holder {
194 struct fsnotify_event *event;
195 struct list_head event_list;
199 * Inotify needs to tack data onto an event. This struct lets us later find the
200 * correct private data of the correct group.
202 struct fsnotify_event_private_data {
203 struct fsnotify_group *group;
204 struct list_head event_list;
208 * all of the information about the original object we want to now send to
209 * a group. If you want to carry more info from the accessing task to the
210 * listener this structure is where you need to be adding fields.
212 struct fsnotify_event {
214 * If we create an event we are also likely going to need a holder
215 * to link to a group. So embed one holder in the event. Means only
216 * one allocation for the common case where we only have one group
218 struct fsnotify_event_holder holder;
219 spinlock_t lock; /* protection for the associated event_holder and private_list */
220 /* to_tell may ONLY be dereferenced during handle_event(). */
221 struct inode *to_tell; /* either the inode the event happened to or its parent */
223 * depending on the event type we should have either a path or inode
224 * We hold a reference on path, but NOT on inode. Since we have the ref on
225 * the path, it may be dereferenced at any point during this object's
226 * lifetime. That reference is dropped when this object's refcnt hits
227 * 0. If this event contains an inode instead of a path, the inode may
228 * ONLY be used during handle_event().
234 /* when calling fsnotify tell it if the data is a path or inode */
235 #define FSNOTIFY_EVENT_NONE 0
236 #define FSNOTIFY_EVENT_PATH 1
237 #define FSNOTIFY_EVENT_INODE 2
238 int data_type; /* which of the above union we have */
239 atomic_t refcnt; /* how many groups still are using/need to send this event */
240 __u32 mask; /* the type of access, bitwise OR for FS_* event types */
242 u32 sync_cookie; /* used to corrolate events, namely inotify mv events */
243 const unsigned char *file_name;
247 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
248 __u32 response; /* userspace answer to question */
249 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
251 struct list_head private_data_list; /* groups can store private data here */
255 * Inode specific fields in an fsnotify_mark
257 struct fsnotify_inode_mark {
258 struct inode *inode; /* inode this mark is associated with */
259 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */
260 struct list_head free_i_list; /* tmp list used when freeing this mark */
264 * Mount point specific fields in an fsnotify_mark
266 struct fsnotify_vfsmount_mark {
267 struct vfsmount *mnt; /* vfsmount this mark is associated with */
268 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */
269 struct list_head free_m_list; /* tmp list used when freeing this mark */
273 * a mark is simply an object attached to an in core inode which allows an
274 * fsnotify listener to indicate they are either no longer interested in events
275 * of a type matching mask or only interested in those events.
277 * these are flushed when an inode is evicted from core and may be flushed
278 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
279 * (such as dnotify) will flush these when the open fd is closed and not at
280 * inode eviction or modification.
282 struct fsnotify_mark {
283 __u32 mask; /* mask this mark is for */
284 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
285 * in kernel that found and may be using this mark. */
286 atomic_t refcnt; /* active things looking at this mark */
287 struct fsnotify_group *group; /* group this mark is for */
288 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */
289 spinlock_t lock; /* protect group and inode */
291 struct fsnotify_inode_mark i;
292 struct fsnotify_vfsmount_mark m;
294 __u32 ignored_mask; /* events types to ignore */
295 struct list_head free_g_list; /* tmp list used when freeing this mark */
296 #define FSNOTIFY_MARK_FLAG_INODE 0x01
297 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
298 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
299 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
300 unsigned int flags; /* vfsmount or inode mark? */
301 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
304 #ifdef CONFIG_FSNOTIFY
306 /* called from the vfs helpers */
308 /* main fsnotify call to send events */
309 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
310 const unsigned char *name, u32 cookie);
311 extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
312 extern void __fsnotify_inode_delete(struct inode *inode);
313 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
314 extern u32 fsnotify_get_cookie(void);
316 static inline int fsnotify_inode_watches_children(struct inode *inode)
318 /* FS_EVENT_ON_CHILD is set if the inode may care */
319 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
321 /* this inode might care about child events, does it care about the
322 * specific set of events that can happen on a child? */
323 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
327 * Update the dentry with a flag indicating the interest of its parent to receive
328 * filesystem events when those events happens to this dentry->d_inode.
330 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
332 struct dentry *parent;
334 assert_spin_locked(&dcache_lock);
335 assert_spin_locked(&dentry->d_lock);
337 parent = dentry->d_parent;
338 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
339 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
341 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
345 * fsnotify_d_instantiate - instantiate a dentry for inode
346 * Called with dcache_lock held.
348 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
353 assert_spin_locked(&dcache_lock);
355 spin_lock(&dentry->d_lock);
356 __fsnotify_update_dcache_flags(dentry);
357 spin_unlock(&dentry->d_lock);
360 /* called from fsnotify listeners, such as fanotify or dnotify */
362 /* must call when a group changes its ->mask */
363 extern void fsnotify_recalc_global_mask(void);
364 /* get a reference to an existing or create a new group */
365 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
366 /* run all marks associated with this group and update group->mask */
367 extern void fsnotify_recalc_group_mask(struct fsnotify_group *group);
368 /* drop reference on a group from fsnotify_alloc_group */
369 extern void fsnotify_put_group(struct fsnotify_group *group);
371 /* take a reference to an event */
372 extern void fsnotify_get_event(struct fsnotify_event *event);
373 extern void fsnotify_put_event(struct fsnotify_event *event);
374 /* find private data previously attached to an event and unlink it */
375 extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group,
376 struct fsnotify_event *event);
378 /* attach the event to the group notification queue */
379 extern int fsnotify_add_notify_event(struct fsnotify_group *group,
380 struct fsnotify_event *event,
381 struct fsnotify_event_private_data *priv,
382 int (*merge)(struct list_head *,
383 struct fsnotify_event *,
386 /* true if the group notification queue is empty */
387 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
388 /* return, but do not dequeue the first event on the notification queue */
389 extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group);
390 /* return AND dequeue the first event on the notification queue */
391 extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group);
393 /* functions used to manipulate the marks attached to inodes */
395 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
396 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
397 /* run all marks associated with an inode and update inode->i_fsnotify_mask */
398 extern void fsnotify_recalc_inode_mask(struct inode *inode);
399 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
400 /* find (and take a reference) to a mark associated with group and inode */
401 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
402 /* find (and take a reference) to a mark associated with group and vfsmount */
403 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
404 /* copy the values from old into new */
405 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
406 /* set the ignored_mask of a mark */
407 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
408 /* set the mask of a mark (might pin the object into memory */
409 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
410 /* attach the mark to both the group and the inode */
411 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
412 struct inode *inode, struct vfsmount *mnt, int allow_dups);
413 /* given a mark, flag it to be freed when all references are dropped */
414 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark);
415 /* run all the marks in a group, and clear all of the vfsmount marks */
416 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
417 /* run all the marks in a group, and clear all of the inode marks */
418 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
419 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
420 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
421 /* run all the marks in a group, and flag them to be freed */
422 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
423 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
424 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
425 extern void fsnotify_unmount_inodes(struct list_head *list);
427 /* put here because inotify does some weird stuff when destroying watches */
428 extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
429 void *data, int data_is,
430 const unsigned char *name,
431 u32 cookie, gfp_t gfp);
433 /* fanotify likes to change events after they are on lists... */
434 extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event);
435 extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder,
436 struct fsnotify_event *new_event);
440 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
441 const unsigned char *name, u32 cookie)
446 static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
449 static inline void __fsnotify_inode_delete(struct inode *inode)
452 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
455 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
458 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
461 static inline u32 fsnotify_get_cookie(void)
466 static inline void fsnotify_unmount_inodes(struct list_head *list)
469 #endif /* CONFIG_FSNOTIFY */
471 #endif /* __KERNEL __ */
473 #endif /* __LINUX_FSNOTIFY_BACKEND_H */