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90586523 EP |
1 | /* |
2 | * Filesystem access notification for Linux | |
3 | * | |
4 | * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> | |
5 | */ | |
6 | ||
7 | #ifndef __LINUX_FSNOTIFY_BACKEND_H | |
8 | #define __LINUX_FSNOTIFY_BACKEND_H | |
9 | ||
10 | #ifdef __KERNEL__ | |
11 | ||
63c882a0 | 12 | #include <linux/idr.h> /* inotify uses this */ |
90586523 EP |
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 | ||
19 | #include <asm/atomic.h> | |
20 | ||
21 | /* | |
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. | |
26 | */ | |
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 */ | |
39 | ||
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 */ | |
43 | ||
44 | #define FS_IN_ISDIR 0x40000000 /* event occurred against dir */ | |
45 | #define FS_IN_ONESHOT 0x80000000 /* only send event once */ | |
46 | ||
47 | #define FS_DN_RENAME 0x10000000 /* file renamed */ | |
48 | #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ | |
49 | ||
c28f7e56 EP |
50 | /* This inode cares about things that happen to its children. Always set for |
51 | * dnotify and inotify. */ | |
52 | #define FS_EVENT_ON_CHILD 0x08000000 | |
53 | ||
54 | /* This is a list of all events that may get sent to a parernt based on fs event | |
55 | * happening to inodes inside that directory */ | |
56 | #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ | |
57 | FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ | |
58 | FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ | |
59 | FS_DELETE) | |
60 | ||
e9fd702a EP |
61 | #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) |
62 | ||
90586523 EP |
63 | struct fsnotify_group; |
64 | struct fsnotify_event; | |
3be25f49 | 65 | struct fsnotify_mark_entry; |
e4aff117 | 66 | struct fsnotify_event_private_data; |
90586523 EP |
67 | |
68 | /* | |
69 | * Each group much define these ops. The fsnotify infrastructure will call | |
70 | * these operations for each relevant group. | |
71 | * | |
3be25f49 EP |
72 | * should_send_event - given a group, inode, and mask this function determines |
73 | * if the group is interested in this event. | |
90586523 EP |
74 | * handle_event - main call for a group to handle an fs event |
75 | * free_group_priv - called when a group refcnt hits 0 to clean up the private union | |
3be25f49 EP |
76 | * freeing-mark - this means that a mark has been flagged to die when everything |
77 | * finishes using it. The function is supplied with what must be a | |
78 | * valid group and inode to use to clean up. | |
90586523 EP |
79 | */ |
80 | struct fsnotify_ops { | |
7b0a04fb | 81 | bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, |
3a9fb89f EP |
82 | struct vfsmount *mnt, __u32 mask, void *data, |
83 | int data_type); | |
90586523 EP |
84 | int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event); |
85 | void (*free_group_priv)(struct fsnotify_group *group); | |
3be25f49 | 86 | void (*freeing_mark)(struct fsnotify_mark_entry *entry, struct fsnotify_group *group); |
e4aff117 | 87 | void (*free_event_priv)(struct fsnotify_event_private_data *priv); |
90586523 EP |
88 | }; |
89 | ||
90 | /* | |
91 | * A group is a "thing" that wants to receive notification about filesystem | |
92 | * events. The mask holds the subset of event types this group cares about. | |
93 | * refcnt on a group is up to the implementor and at any moment if it goes 0 | |
94 | * everything will be cleaned up. | |
95 | */ | |
96 | struct fsnotify_group { | |
97 | /* | |
98 | * global list of all groups receiving events from fsnotify. | |
19c2a0e1 | 99 | * anchored by fsnotify_inode_groups and protected by either fsnotify_grp_mutex |
90586523 EP |
100 | * or fsnotify_grp_srcu depending on write vs read. |
101 | */ | |
19c2a0e1 | 102 | struct list_head inode_group_list; |
7131485a EP |
103 | /* |
104 | * same as above except anchored by fsnotify_vfsmount_groups | |
105 | */ | |
106 | struct list_head vfsmount_group_list; | |
90586523 EP |
107 | |
108 | /* | |
109 | * Defines all of the event types in which this group is interested. | |
110 | * This mask is a bitwise OR of the FS_* events from above. Each time | |
111 | * this mask changes for a group (if it changes) the correct functions | |
112 | * must be called to update the global structures which indicate global | |
113 | * interest in event types. | |
114 | */ | |
115 | __u32 mask; | |
116 | ||
117 | /* | |
118 | * How the refcnt is used is up to each group. When the refcnt hits 0 | |
119 | * fsnotify will clean up all of the resources associated with this group. | |
120 | * As an example, the dnotify group will always have a refcnt=1 and that | |
121 | * will never change. Inotify, on the other hand, has a group per | |
122 | * inotify_init() and the refcnt will hit 0 only when that fd has been | |
123 | * closed. | |
124 | */ | |
125 | atomic_t refcnt; /* things with interest in this group */ | |
90586523 EP |
126 | |
127 | const struct fsnotify_ops *ops; /* how this group handles things */ | |
128 | ||
a2d8bc6c EP |
129 | /* needed to send notification to userspace */ |
130 | struct mutex notification_mutex; /* protect the notification_list */ | |
131 | struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ | |
132 | wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ | |
133 | unsigned int q_len; /* events on the queue */ | |
134 | unsigned int max_events; /* maximum events allowed on the list */ | |
135 | ||
3be25f49 EP |
136 | /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */ |
137 | spinlock_t mark_lock; /* protect mark_entries list */ | |
138 | atomic_t num_marks; /* 1 for each mark entry and 1 for not being | |
139 | * past the point of no return when freeing | |
140 | * a group */ | |
141 | struct list_head mark_entries; /* all inode mark entries for this group */ | |
142 | ||
143 | /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */ | |
19c2a0e1 | 144 | bool on_inode_group_list; |
7131485a | 145 | bool on_vfsmount_group_list; |
90586523 EP |
146 | |
147 | /* groups can define private fields here or use the void *private */ | |
148 | union { | |
149 | void *private; | |
63c882a0 EP |
150 | #ifdef CONFIG_INOTIFY_USER |
151 | struct inotify_group_private_data { | |
152 | spinlock_t idr_lock; | |
153 | struct idr idr; | |
154 | u32 last_wd; | |
155 | struct fasync_struct *fa; /* async notification */ | |
156 | struct user_struct *user; | |
157 | } inotify_data; | |
158 | #endif | |
90586523 EP |
159 | }; |
160 | }; | |
161 | ||
a2d8bc6c EP |
162 | /* |
163 | * A single event can be queued in multiple group->notification_lists. | |
164 | * | |
165 | * each group->notification_list will point to an event_holder which in turns points | |
166 | * to the actual event that needs to be sent to userspace. | |
167 | * | |
168 | * Seemed cheaper to create a refcnt'd event and a small holder for every group | |
169 | * than create a different event for every group | |
170 | * | |
171 | */ | |
172 | struct fsnotify_event_holder { | |
173 | struct fsnotify_event *event; | |
174 | struct list_head event_list; | |
175 | }; | |
176 | ||
e4aff117 EP |
177 | /* |
178 | * Inotify needs to tack data onto an event. This struct lets us later find the | |
179 | * correct private data of the correct group. | |
180 | */ | |
181 | struct fsnotify_event_private_data { | |
182 | struct fsnotify_group *group; | |
183 | struct list_head event_list; | |
184 | }; | |
185 | ||
90586523 EP |
186 | /* |
187 | * all of the information about the original object we want to now send to | |
188 | * a group. If you want to carry more info from the accessing task to the | |
189 | * listener this structure is where you need to be adding fields. | |
190 | */ | |
191 | struct fsnotify_event { | |
a2d8bc6c EP |
192 | /* |
193 | * If we create an event we are also likely going to need a holder | |
194 | * to link to a group. So embed one holder in the event. Means only | |
195 | * one allocation for the common case where we only have one group | |
196 | */ | |
197 | struct fsnotify_event_holder holder; | |
90586523 EP |
198 | spinlock_t lock; /* protection for the associated event_holder and private_list */ |
199 | /* to_tell may ONLY be dereferenced during handle_event(). */ | |
200 | struct inode *to_tell; /* either the inode the event happened to or its parent */ | |
201 | /* | |
202 | * depending on the event type we should have either a path or inode | |
203 | * We hold a reference on path, but NOT on inode. Since we have the ref on | |
204 | * the path, it may be dereferenced at any point during this object's | |
205 | * lifetime. That reference is dropped when this object's refcnt hits | |
206 | * 0. If this event contains an inode instead of a path, the inode may | |
207 | * ONLY be used during handle_event(). | |
208 | */ | |
209 | union { | |
210 | struct path path; | |
211 | struct inode *inode; | |
212 | }; | |
213 | /* when calling fsnotify tell it if the data is a path or inode */ | |
214 | #define FSNOTIFY_EVENT_NONE 0 | |
215 | #define FSNOTIFY_EVENT_PATH 1 | |
216 | #define FSNOTIFY_EVENT_INODE 2 | |
90586523 EP |
217 | int data_type; /* which of the above union we have */ |
218 | atomic_t refcnt; /* how many groups still are using/need to send this event */ | |
219 | __u32 mask; /* the type of access, bitwise OR for FS_* event types */ | |
62ffe5df | 220 | |
47882c6f | 221 | u32 sync_cookie; /* used to corrolate events, namely inotify mv events */ |
62ffe5df EP |
222 | char *file_name; |
223 | size_t name_len; | |
e4aff117 EP |
224 | |
225 | struct list_head private_data_list; /* groups can store private data here */ | |
90586523 EP |
226 | }; |
227 | ||
2823e04d EP |
228 | /* |
229 | * Inode specific fields in an fsnotify_mark_entry | |
230 | */ | |
231 | struct fsnotify_inode_mark { | |
232 | struct inode *inode; /* inode this entry is associated with */ | |
233 | struct hlist_node i_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */ | |
234 | struct list_head free_i_list; /* tmp list used when freeing this mark */ | |
235 | }; | |
236 | ||
4136510d EP |
237 | /* |
238 | * Mount point specific fields in an fsnotify_mark_entry | |
239 | */ | |
240 | struct fsnotify_vfsmount_mark { | |
241 | struct vfsmount *mnt; /* inode this entry is associated with */ | |
242 | struct hlist_node m_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */ | |
243 | struct list_head free_m_list; /* tmp list used when freeing this mark */ | |
244 | }; | |
245 | ||
3be25f49 EP |
246 | /* |
247 | * a mark is simply an entry attached to an in core inode which allows an | |
248 | * fsnotify listener to indicate they are either no longer interested in events | |
249 | * of a type matching mask or only interested in those events. | |
250 | * | |
251 | * these are flushed when an inode is evicted from core and may be flushed | |
252 | * when the inode is modified (as seen by fsnotify_access). Some fsnotify users | |
253 | * (such as dnotify) will flush these when the open fd is closed and not at | |
254 | * inode eviction or modification. | |
255 | */ | |
256 | struct fsnotify_mark_entry { | |
257 | __u32 mask; /* mask this mark entry is for */ | |
258 | /* we hold ref for each i_list and g_list. also one ref for each 'thing' | |
259 | * in kernel that found and may be using this mark. */ | |
260 | atomic_t refcnt; /* active things looking at this mark */ | |
3be25f49 | 261 | struct fsnotify_group *group; /* group this mark entry is for */ |
3be25f49 | 262 | struct list_head g_list; /* list of mark_entries by group->i_fsnotify_mark_entries */ |
2823e04d EP |
263 | spinlock_t lock; /* protect group and inode */ |
264 | union { | |
265 | struct fsnotify_inode_mark i; | |
4136510d | 266 | struct fsnotify_vfsmount_mark m; |
2823e04d | 267 | }; |
3be25f49 | 268 | struct list_head free_g_list; /* tmp list used when freeing this mark */ |
098cf2fc EP |
269 | #define FSNOTIFY_MARK_FLAG_INODE 0x01 |
270 | #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 | |
271 | unsigned int flags; /* vfsmount or inode mark? */ | |
3be25f49 EP |
272 | void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */ |
273 | }; | |
274 | ||
90586523 EP |
275 | #ifdef CONFIG_FSNOTIFY |
276 | ||
277 | /* called from the vfs helpers */ | |
278 | ||
279 | /* main fsnotify call to send events */ | |
47882c6f EP |
280 | extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
281 | const char *name, u32 cookie); | |
72acc854 | 282 | extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); |
3be25f49 | 283 | extern void __fsnotify_inode_delete(struct inode *inode); |
47882c6f | 284 | extern u32 fsnotify_get_cookie(void); |
90586523 | 285 | |
c28f7e56 EP |
286 | static inline int fsnotify_inode_watches_children(struct inode *inode) |
287 | { | |
288 | /* FS_EVENT_ON_CHILD is set if the inode may care */ | |
289 | if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) | |
290 | return 0; | |
291 | /* this inode might care about child events, does it care about the | |
292 | * specific set of events that can happen on a child? */ | |
293 | return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; | |
294 | } | |
295 | ||
296 | /* | |
297 | * Update the dentry with a flag indicating the interest of its parent to receive | |
298 | * filesystem events when those events happens to this dentry->d_inode. | |
299 | */ | |
300 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) | |
301 | { | |
302 | struct dentry *parent; | |
303 | ||
304 | assert_spin_locked(&dcache_lock); | |
305 | assert_spin_locked(&dentry->d_lock); | |
306 | ||
307 | parent = dentry->d_parent; | |
e6ce3066 | 308 | if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) |
c28f7e56 EP |
309 | dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; |
310 | else | |
311 | dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
312 | } | |
313 | ||
314 | /* | |
315 | * fsnotify_d_instantiate - instantiate a dentry for inode | |
316 | * Called with dcache_lock held. | |
317 | */ | |
318 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) | |
319 | { | |
320 | if (!inode) | |
321 | return; | |
322 | ||
323 | assert_spin_locked(&dcache_lock); | |
324 | ||
325 | spin_lock(&dentry->d_lock); | |
326 | __fsnotify_update_dcache_flags(dentry); | |
327 | spin_unlock(&dentry->d_lock); | |
328 | } | |
90586523 EP |
329 | |
330 | /* called from fsnotify listeners, such as fanotify or dnotify */ | |
331 | ||
332 | /* must call when a group changes its ->mask */ | |
333 | extern void fsnotify_recalc_global_mask(void); | |
334 | /* get a reference to an existing or create a new group */ | |
0d2e2a1d | 335 | extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); |
3be25f49 EP |
336 | /* run all marks associated with this group and update group->mask */ |
337 | extern void fsnotify_recalc_group_mask(struct fsnotify_group *group); | |
ffab8340 | 338 | /* drop reference on a group from fsnotify_alloc_group */ |
90586523 EP |
339 | extern void fsnotify_put_group(struct fsnotify_group *group); |
340 | ||
341 | /* take a reference to an event */ | |
342 | extern void fsnotify_get_event(struct fsnotify_event *event); | |
343 | extern void fsnotify_put_event(struct fsnotify_event *event); | |
e4aff117 EP |
344 | /* find private data previously attached to an event and unlink it */ |
345 | extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, | |
346 | struct fsnotify_event *event); | |
90586523 | 347 | |
a2d8bc6c | 348 | /* attach the event to the group notification queue */ |
74766bbf EP |
349 | extern int fsnotify_add_notify_event(struct fsnotify_group *group, |
350 | struct fsnotify_event *event, | |
351 | struct fsnotify_event_private_data *priv, | |
352 | int (*merge)(struct list_head *, struct fsnotify_event *)); | |
a2d8bc6c EP |
353 | /* true if the group notification queue is empty */ |
354 | extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); | |
355 | /* return, but do not dequeue the first event on the notification queue */ | |
356 | extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); | |
e4aff117 | 357 | /* return AND dequeue the first event on the notification queue */ |
a2d8bc6c EP |
358 | extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); |
359 | ||
3be25f49 EP |
360 | /* functions used to manipulate the marks attached to inodes */ |
361 | ||
362 | /* run all marks associated with an inode and update inode->i_fsnotify_mask */ | |
363 | extern void fsnotify_recalc_inode_mask(struct inode *inode); | |
364 | extern void fsnotify_init_mark(struct fsnotify_mark_entry *entry, void (*free_mark)(struct fsnotify_mark_entry *entry)); | |
365 | /* find (and take a reference) to a mark associated with group and inode */ | |
366 | extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, struct inode *inode); | |
9e1c7432 EP |
367 | /* copy the values from old into new */ |
368 | extern void fsnotify_duplicate_mark(struct fsnotify_mark_entry *new, struct fsnotify_mark_entry *old); | |
3be25f49 | 369 | /* attach the mark to both the group and the inode */ |
40554c3d | 370 | extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode, int allow_dups); |
3be25f49 EP |
371 | /* given a mark, flag it to be freed when all references are dropped */ |
372 | extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry); | |
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_entry *entry); | |
376 | extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry); | |
164bc619 | 377 | extern void fsnotify_unmount_inodes(struct list_head *list); |
3be25f49 | 378 | |
90586523 EP |
379 | /* put here because inotify does some weird stuff when destroying watches */ |
380 | extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, | |
47882c6f | 381 | void *data, int data_is, const char *name, |
f44aebcc | 382 | u32 cookie, gfp_t gfp); |
62ffe5df | 383 | |
b4e4e140 EP |
384 | /* fanotify likes to change events after they are on lists... */ |
385 | extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event); | |
1201a536 EP |
386 | extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder, |
387 | struct fsnotify_event *new_event); | |
b4e4e140 | 388 | |
90586523 EP |
389 | #else |
390 | ||
62ffe5df | 391 | static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
47882c6f | 392 | const char *name, u32 cookie) |
90586523 | 393 | {} |
3be25f49 | 394 | |
72acc854 | 395 | static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) |
c28f7e56 EP |
396 | {} |
397 | ||
3be25f49 EP |
398 | static inline void __fsnotify_inode_delete(struct inode *inode) |
399 | {} | |
400 | ||
c28f7e56 EP |
401 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) |
402 | {} | |
403 | ||
404 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) | |
405 | {} | |
406 | ||
47882c6f EP |
407 | static inline u32 fsnotify_get_cookie(void) |
408 | { | |
409 | return 0; | |
410 | } | |
411 | ||
164bc619 EP |
412 | static inline void fsnotify_unmount_inodes(struct list_head *list) |
413 | {} | |
414 | ||
90586523 EP |
415 | #endif /* CONFIG_FSNOTIFY */ |
416 | ||
417 | #endif /* __KERNEL __ */ | |
418 | ||
419 | #endif /* __LINUX_FSNOTIFY_BACKEND_H */ |