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 fsnotify_mark
*inode_mark
,
96 struct fsnotify_mark
*vfsmount_mark
,
97 __u32 mask
, void *data
, int data_type
);
98 int (*handle_event
)(struct fsnotify_group
*group
,
99 struct fsnotify_mark
*inode_mark
,
100 struct fsnotify_mark
*vfsmount_mark
,
101 struct fsnotify_event
*event
);
102 void (*free_group_priv
)(struct fsnotify_group
*group
);
103 void (*freeing_mark
)(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
);
104 void (*free_event_priv
)(struct fsnotify_event_private_data
*priv
);
108 * A group is a "thing" that wants to receive notification about filesystem
109 * events. The mask holds the subset of event types this group cares about.
110 * refcnt on a group is up to the implementor and at any moment if it goes 0
111 * everything will be cleaned up.
113 struct fsnotify_group
{
115 * How the refcnt is used is up to each group. When the refcnt hits 0
116 * fsnotify will clean up all of the resources associated with this group.
117 * As an example, the dnotify group will always have a refcnt=1 and that
118 * will never change. Inotify, on the other hand, has a group per
119 * inotify_init() and the refcnt will hit 0 only when that fd has been
122 atomic_t refcnt
; /* things with interest in this group */
124 const struct fsnotify_ops
*ops
; /* how this group handles things */
126 /* needed to send notification to userspace */
127 struct mutex notification_mutex
; /* protect the notification_list */
128 struct list_head notification_list
; /* list of event_holder this group needs to send to userspace */
129 wait_queue_head_t notification_waitq
; /* read() on the notification file blocks on this waitq */
130 unsigned int q_len
; /* events on the queue */
131 unsigned int max_events
; /* maximum events allowed on the list */
133 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
134 spinlock_t mark_lock
; /* protect marks_list */
135 atomic_t num_marks
; /* 1 for each mark and 1 for not being
136 * past the point of no return when freeing
138 struct list_head marks_list
; /* all inode marks for this group */
140 /* groups can define private fields here or use the void *private */
143 #ifdef CONFIG_INOTIFY_USER
144 struct inotify_group_private_data
{
148 struct fasync_struct
*fa
; /* async notification */
149 struct user_struct
*user
;
152 #ifdef CONFIG_FANOTIFY
153 struct fanotify_group_private_data
{
154 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
155 /* allows a group to block waiting for a userspace response */
156 struct mutex access_mutex
;
157 struct list_head access_list
;
158 wait_queue_head_t access_waitq
;
159 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
162 #endif /* CONFIG_FANOTIFY */
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 file or inode
207 * We hold a reference on file, but NOT on inode. Since we have the ref on
208 * the file, 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 file, 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_FILE 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 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
231 __u32 response
; /* userspace answer to question */
232 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
234 struct list_head private_data_list
; /* groups can store private data here */
238 * Inode specific fields in an fsnotify_mark
240 struct fsnotify_inode_mark
{
241 struct inode
*inode
; /* inode this mark is associated with */
242 struct hlist_node i_list
; /* list of marks by inode->i_fsnotify_marks */
243 struct list_head free_i_list
; /* tmp list used when freeing this mark */
247 * Mount point specific fields in an fsnotify_mark
249 struct fsnotify_vfsmount_mark
{
250 struct vfsmount
*mnt
; /* vfsmount this mark is associated with */
251 struct hlist_node m_list
; /* list of marks by inode->i_fsnotify_marks */
252 struct list_head free_m_list
; /* tmp list used when freeing this mark */
256 * a mark is simply an object attached to an in core inode which allows an
257 * fsnotify listener to indicate they are either no longer interested in events
258 * of a type matching mask or only interested in those events.
260 * these are flushed when an inode is evicted from core and may be flushed
261 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
262 * (such as dnotify) will flush these when the open fd is closed and not at
263 * inode eviction or modification.
265 struct fsnotify_mark
{
266 __u32 mask
; /* mask this mark is for */
267 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
268 * in kernel that found and may be using this mark. */
269 atomic_t refcnt
; /* active things looking at this mark */
270 struct fsnotify_group
*group
; /* group this mark is for */
271 struct list_head g_list
; /* list of marks by group->i_fsnotify_marks */
272 spinlock_t lock
; /* protect group and inode */
274 struct fsnotify_inode_mark i
;
275 struct fsnotify_vfsmount_mark m
;
277 __u32 ignored_mask
; /* events types to ignore */
278 struct list_head free_g_list
; /* tmp list used when freeing this mark */
279 #define FSNOTIFY_MARK_FLAG_INODE 0x01
280 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
281 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
282 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
283 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10
284 unsigned int flags
; /* vfsmount or inode mark? */
285 struct list_head destroy_list
;
286 void (*free_mark
)(struct fsnotify_mark
*mark
); /* called on final put+free */
289 #ifdef CONFIG_FSNOTIFY
291 /* called from the vfs helpers */
293 /* main fsnotify call to send events */
294 extern int fsnotify(struct inode
*to_tell
, __u32 mask
, void *data
, int data_is
,
295 const unsigned char *name
, u32 cookie
);
296 extern void __fsnotify_parent(struct file
*file
, struct dentry
*dentry
, __u32 mask
);
297 extern void __fsnotify_inode_delete(struct inode
*inode
);
298 extern void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
);
299 extern u32
fsnotify_get_cookie(void);
301 static inline int fsnotify_inode_watches_children(struct inode
*inode
)
303 /* FS_EVENT_ON_CHILD is set if the inode may care */
304 if (!(inode
->i_fsnotify_mask
& FS_EVENT_ON_CHILD
))
306 /* this inode might care about child events, does it care about the
307 * specific set of events that can happen on a child? */
308 return inode
->i_fsnotify_mask
& FS_EVENTS_POSS_ON_CHILD
;
312 * Update the dentry with a flag indicating the interest of its parent to receive
313 * filesystem events when those events happens to this dentry->d_inode.
315 static inline void __fsnotify_update_dcache_flags(struct dentry
*dentry
)
317 struct dentry
*parent
;
319 assert_spin_locked(&dcache_lock
);
320 assert_spin_locked(&dentry
->d_lock
);
322 parent
= dentry
->d_parent
;
323 if (parent
->d_inode
&& fsnotify_inode_watches_children(parent
->d_inode
))
324 dentry
->d_flags
|= DCACHE_FSNOTIFY_PARENT_WATCHED
;
326 dentry
->d_flags
&= ~DCACHE_FSNOTIFY_PARENT_WATCHED
;
330 * fsnotify_d_instantiate - instantiate a dentry for inode
331 * Called with dcache_lock held.
333 static inline void __fsnotify_d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
338 assert_spin_locked(&dcache_lock
);
340 spin_lock(&dentry
->d_lock
);
341 __fsnotify_update_dcache_flags(dentry
);
342 spin_unlock(&dentry
->d_lock
);
345 /* called from fsnotify listeners, such as fanotify or dnotify */
347 /* get a reference to an existing or create a new group */
348 extern struct fsnotify_group
*fsnotify_alloc_group(const struct fsnotify_ops
*ops
);
349 /* drop reference on a group from fsnotify_alloc_group */
350 extern void fsnotify_put_group(struct fsnotify_group
*group
);
352 /* take a reference to an event */
353 extern void fsnotify_get_event(struct fsnotify_event
*event
);
354 extern void fsnotify_put_event(struct fsnotify_event
*event
);
355 /* find private data previously attached to an event and unlink it */
356 extern struct fsnotify_event_private_data
*fsnotify_remove_priv_from_event(struct fsnotify_group
*group
,
357 struct fsnotify_event
*event
);
359 /* attach the event to the group notification queue */
360 extern struct fsnotify_event
*fsnotify_add_notify_event(struct fsnotify_group
*group
,
361 struct fsnotify_event
*event
,
362 struct fsnotify_event_private_data
*priv
,
363 struct fsnotify_event
*(*merge
)(struct list_head
*,
364 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 file
*file
, 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 */