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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 | ||
12 | #include <linux/fs.h> /* struct inode */ | |
13 | #include <linux/list.h> | |
14 | #include <linux/path.h> /* struct path */ | |
15 | #include <linux/spinlock.h> | |
16 | #include <linux/types.h> | |
17 | ||
18 | #include <asm/atomic.h> | |
19 | ||
20 | /* | |
21 | * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily | |
22 | * convert between them. dnotify only needs conversion at watch creation | |
23 | * so no perf loss there. fanotify isn't defined yet, so it can use the | |
24 | * wholes if it needs more events. | |
25 | */ | |
26 | #define FS_ACCESS 0x00000001 /* File was accessed */ | |
27 | #define FS_MODIFY 0x00000002 /* File was modified */ | |
28 | #define FS_ATTRIB 0x00000004 /* Metadata changed */ | |
29 | #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */ | |
30 | #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */ | |
31 | #define FS_OPEN 0x00000020 /* File was opened */ | |
32 | #define FS_MOVED_FROM 0x00000040 /* File was moved from X */ | |
33 | #define FS_MOVED_TO 0x00000080 /* File was moved to Y */ | |
34 | #define FS_CREATE 0x00000100 /* Subfile was created */ | |
35 | #define FS_DELETE 0x00000200 /* Subfile was deleted */ | |
36 | #define FS_DELETE_SELF 0x00000400 /* Self was deleted */ | |
37 | #define FS_MOVE_SELF 0x00000800 /* Self was moved */ | |
38 | ||
39 | #define FS_UNMOUNT 0x00002000 /* inode on umount fs */ | |
40 | #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */ | |
41 | #define FS_IN_IGNORED 0x00008000 /* last inotify event here */ | |
42 | ||
43 | #define FS_IN_ISDIR 0x40000000 /* event occurred against dir */ | |
44 | #define FS_IN_ONESHOT 0x80000000 /* only send event once */ | |
45 | ||
46 | #define FS_DN_RENAME 0x10000000 /* file renamed */ | |
47 | #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ | |
48 | ||
c28f7e56 EP |
49 | /* This inode cares about things that happen to its children. Always set for |
50 | * dnotify and inotify. */ | |
51 | #define FS_EVENT_ON_CHILD 0x08000000 | |
52 | ||
53 | /* This is a list of all events that may get sent to a parernt based on fs event | |
54 | * happening to inodes inside that directory */ | |
55 | #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ | |
56 | FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ | |
57 | FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ | |
58 | FS_DELETE) | |
59 | ||
3c5119c0 EP |
60 | /* listeners that hard code group numbers near the top */ |
61 | #define DNOTIFY_GROUP_NUM UINT_MAX | |
62 | ||
90586523 EP |
63 | struct fsnotify_group; |
64 | struct fsnotify_event; | |
3be25f49 | 65 | struct fsnotify_mark_entry; |
90586523 EP |
66 | |
67 | /* | |
68 | * Each group much define these ops. The fsnotify infrastructure will call | |
69 | * these operations for each relevant group. | |
70 | * | |
3be25f49 EP |
71 | * should_send_event - given a group, inode, and mask this function determines |
72 | * if the group is interested in this event. | |
90586523 EP |
73 | * handle_event - main call for a group to handle an fs event |
74 | * free_group_priv - called when a group refcnt hits 0 to clean up the private union | |
3be25f49 EP |
75 | * freeing-mark - this means that a mark has been flagged to die when everything |
76 | * finishes using it. The function is supplied with what must be a | |
77 | * valid group and inode to use to clean up. | |
90586523 EP |
78 | */ |
79 | struct fsnotify_ops { | |
3be25f49 | 80 | bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, __u32 mask); |
90586523 EP |
81 | int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event); |
82 | void (*free_group_priv)(struct fsnotify_group *group); | |
3be25f49 | 83 | void (*freeing_mark)(struct fsnotify_mark_entry *entry, struct fsnotify_group *group); |
90586523 EP |
84 | }; |
85 | ||
86 | /* | |
87 | * A group is a "thing" that wants to receive notification about filesystem | |
88 | * events. The mask holds the subset of event types this group cares about. | |
89 | * refcnt on a group is up to the implementor and at any moment if it goes 0 | |
90 | * everything will be cleaned up. | |
91 | */ | |
92 | struct fsnotify_group { | |
93 | /* | |
94 | * global list of all groups receiving events from fsnotify. | |
95 | * anchored by fsnotify_groups and protected by either fsnotify_grp_mutex | |
96 | * or fsnotify_grp_srcu depending on write vs read. | |
97 | */ | |
98 | struct list_head group_list; | |
99 | ||
100 | /* | |
101 | * Defines all of the event types in which this group is interested. | |
102 | * This mask is a bitwise OR of the FS_* events from above. Each time | |
103 | * this mask changes for a group (if it changes) the correct functions | |
104 | * must be called to update the global structures which indicate global | |
105 | * interest in event types. | |
106 | */ | |
107 | __u32 mask; | |
108 | ||
109 | /* | |
110 | * How the refcnt is used is up to each group. When the refcnt hits 0 | |
111 | * fsnotify will clean up all of the resources associated with this group. | |
112 | * As an example, the dnotify group will always have a refcnt=1 and that | |
113 | * will never change. Inotify, on the other hand, has a group per | |
114 | * inotify_init() and the refcnt will hit 0 only when that fd has been | |
115 | * closed. | |
116 | */ | |
117 | atomic_t refcnt; /* things with interest in this group */ | |
118 | unsigned int group_num; /* simply prevents accidental group collision */ | |
119 | ||
120 | const struct fsnotify_ops *ops; /* how this group handles things */ | |
121 | ||
a2d8bc6c EP |
122 | /* needed to send notification to userspace */ |
123 | struct mutex notification_mutex; /* protect the notification_list */ | |
124 | struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ | |
125 | wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ | |
126 | unsigned int q_len; /* events on the queue */ | |
127 | unsigned int max_events; /* maximum events allowed on the list */ | |
128 | ||
3be25f49 EP |
129 | /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */ |
130 | spinlock_t mark_lock; /* protect mark_entries list */ | |
131 | atomic_t num_marks; /* 1 for each mark entry and 1 for not being | |
132 | * past the point of no return when freeing | |
133 | * a group */ | |
134 | struct list_head mark_entries; /* all inode mark entries for this group */ | |
135 | ||
136 | /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */ | |
90586523 EP |
137 | bool on_group_list; |
138 | ||
139 | /* groups can define private fields here or use the void *private */ | |
140 | union { | |
141 | void *private; | |
142 | }; | |
143 | }; | |
144 | ||
a2d8bc6c EP |
145 | /* |
146 | * A single event can be queued in multiple group->notification_lists. | |
147 | * | |
148 | * each group->notification_list will point to an event_holder which in turns points | |
149 | * to the actual event that needs to be sent to userspace. | |
150 | * | |
151 | * Seemed cheaper to create a refcnt'd event and a small holder for every group | |
152 | * than create a different event for every group | |
153 | * | |
154 | */ | |
155 | struct fsnotify_event_holder { | |
156 | struct fsnotify_event *event; | |
157 | struct list_head event_list; | |
158 | }; | |
159 | ||
90586523 EP |
160 | /* |
161 | * all of the information about the original object we want to now send to | |
162 | * a group. If you want to carry more info from the accessing task to the | |
163 | * listener this structure is where you need to be adding fields. | |
164 | */ | |
165 | struct fsnotify_event { | |
a2d8bc6c EP |
166 | /* |
167 | * If we create an event we are also likely going to need a holder | |
168 | * to link to a group. So embed one holder in the event. Means only | |
169 | * one allocation for the common case where we only have one group | |
170 | */ | |
171 | struct fsnotify_event_holder holder; | |
90586523 EP |
172 | spinlock_t lock; /* protection for the associated event_holder and private_list */ |
173 | /* to_tell may ONLY be dereferenced during handle_event(). */ | |
174 | struct inode *to_tell; /* either the inode the event happened to or its parent */ | |
175 | /* | |
176 | * depending on the event type we should have either a path or inode | |
177 | * We hold a reference on path, but NOT on inode. Since we have the ref on | |
178 | * the path, it may be dereferenced at any point during this object's | |
179 | * lifetime. That reference is dropped when this object's refcnt hits | |
180 | * 0. If this event contains an inode instead of a path, the inode may | |
181 | * ONLY be used during handle_event(). | |
182 | */ | |
183 | union { | |
184 | struct path path; | |
185 | struct inode *inode; | |
186 | }; | |
187 | /* when calling fsnotify tell it if the data is a path or inode */ | |
188 | #define FSNOTIFY_EVENT_NONE 0 | |
189 | #define FSNOTIFY_EVENT_PATH 1 | |
190 | #define FSNOTIFY_EVENT_INODE 2 | |
191 | #define FSNOTIFY_EVENT_FILE 3 | |
192 | int data_type; /* which of the above union we have */ | |
193 | atomic_t refcnt; /* how many groups still are using/need to send this event */ | |
194 | __u32 mask; /* the type of access, bitwise OR for FS_* event types */ | |
62ffe5df | 195 | |
47882c6f | 196 | u32 sync_cookie; /* used to corrolate events, namely inotify mv events */ |
62ffe5df EP |
197 | char *file_name; |
198 | size_t name_len; | |
90586523 EP |
199 | }; |
200 | ||
3be25f49 EP |
201 | /* |
202 | * a mark is simply an entry attached to an in core inode which allows an | |
203 | * fsnotify listener to indicate they are either no longer interested in events | |
204 | * of a type matching mask or only interested in those events. | |
205 | * | |
206 | * these are flushed when an inode is evicted from core and may be flushed | |
207 | * when the inode is modified (as seen by fsnotify_access). Some fsnotify users | |
208 | * (such as dnotify) will flush these when the open fd is closed and not at | |
209 | * inode eviction or modification. | |
210 | */ | |
211 | struct fsnotify_mark_entry { | |
212 | __u32 mask; /* mask this mark entry is for */ | |
213 | /* we hold ref for each i_list and g_list. also one ref for each 'thing' | |
214 | * in kernel that found and may be using this mark. */ | |
215 | atomic_t refcnt; /* active things looking at this mark */ | |
216 | struct inode *inode; /* inode this entry is associated with */ | |
217 | struct fsnotify_group *group; /* group this mark entry is for */ | |
218 | struct hlist_node i_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */ | |
219 | struct list_head g_list; /* list of mark_entries by group->i_fsnotify_mark_entries */ | |
220 | spinlock_t lock; /* protect group, inode, and killme */ | |
221 | struct list_head free_i_list; /* tmp list used when freeing this mark */ | |
222 | struct list_head free_g_list; /* tmp list used when freeing this mark */ | |
223 | void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */ | |
224 | }; | |
225 | ||
90586523 EP |
226 | #ifdef CONFIG_FSNOTIFY |
227 | ||
228 | /* called from the vfs helpers */ | |
229 | ||
230 | /* main fsnotify call to send events */ | |
47882c6f EP |
231 | extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
232 | const char *name, u32 cookie); | |
c28f7e56 | 233 | extern void __fsnotify_parent(struct dentry *dentry, __u32 mask); |
3be25f49 | 234 | extern void __fsnotify_inode_delete(struct inode *inode); |
47882c6f | 235 | extern u32 fsnotify_get_cookie(void); |
90586523 | 236 | |
c28f7e56 EP |
237 | static inline int fsnotify_inode_watches_children(struct inode *inode) |
238 | { | |
239 | /* FS_EVENT_ON_CHILD is set if the inode may care */ | |
240 | if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) | |
241 | return 0; | |
242 | /* this inode might care about child events, does it care about the | |
243 | * specific set of events that can happen on a child? */ | |
244 | return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; | |
245 | } | |
246 | ||
247 | /* | |
248 | * Update the dentry with a flag indicating the interest of its parent to receive | |
249 | * filesystem events when those events happens to this dentry->d_inode. | |
250 | */ | |
251 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) | |
252 | { | |
253 | struct dentry *parent; | |
254 | ||
255 | assert_spin_locked(&dcache_lock); | |
256 | assert_spin_locked(&dentry->d_lock); | |
257 | ||
258 | parent = dentry->d_parent; | |
259 | if (fsnotify_inode_watches_children(parent->d_inode)) | |
260 | dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; | |
261 | else | |
262 | dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
263 | } | |
264 | ||
265 | /* | |
266 | * fsnotify_d_instantiate - instantiate a dentry for inode | |
267 | * Called with dcache_lock held. | |
268 | */ | |
269 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) | |
270 | { | |
271 | if (!inode) | |
272 | return; | |
273 | ||
274 | assert_spin_locked(&dcache_lock); | |
275 | ||
276 | spin_lock(&dentry->d_lock); | |
277 | __fsnotify_update_dcache_flags(dentry); | |
278 | spin_unlock(&dentry->d_lock); | |
279 | } | |
90586523 EP |
280 | |
281 | /* called from fsnotify listeners, such as fanotify or dnotify */ | |
282 | ||
283 | /* must call when a group changes its ->mask */ | |
284 | extern void fsnotify_recalc_global_mask(void); | |
285 | /* get a reference to an existing or create a new group */ | |
286 | extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, | |
287 | __u32 mask, | |
288 | const struct fsnotify_ops *ops); | |
3be25f49 EP |
289 | /* run all marks associated with this group and update group->mask */ |
290 | extern void fsnotify_recalc_group_mask(struct fsnotify_group *group); | |
90586523 EP |
291 | /* drop reference on a group from fsnotify_obtain_group */ |
292 | extern void fsnotify_put_group(struct fsnotify_group *group); | |
293 | ||
294 | /* take a reference to an event */ | |
295 | extern void fsnotify_get_event(struct fsnotify_event *event); | |
296 | extern void fsnotify_put_event(struct fsnotify_event *event); | |
297 | /* find private data previously attached to an event */ | |
298 | extern struct fsnotify_event_private_data *fsnotify_get_priv_from_event(struct fsnotify_group *group, | |
299 | struct fsnotify_event *event); | |
300 | ||
a2d8bc6c EP |
301 | /* attach the event to the group notification queue */ |
302 | extern int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event); | |
303 | /* true if the group notification queue is empty */ | |
304 | extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); | |
305 | /* return, but do not dequeue the first event on the notification queue */ | |
306 | extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); | |
307 | /* reutnr AND dequeue the first event on the notification queue */ | |
308 | extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); | |
309 | ||
3be25f49 EP |
310 | /* functions used to manipulate the marks attached to inodes */ |
311 | ||
312 | /* run all marks associated with an inode and update inode->i_fsnotify_mask */ | |
313 | extern void fsnotify_recalc_inode_mask(struct inode *inode); | |
314 | extern void fsnotify_init_mark(struct fsnotify_mark_entry *entry, void (*free_mark)(struct fsnotify_mark_entry *entry)); | |
315 | /* find (and take a reference) to a mark associated with group and inode */ | |
316 | extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, struct inode *inode); | |
317 | /* attach the mark to both the group and the inode */ | |
318 | extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode); | |
319 | /* given a mark, flag it to be freed when all references are dropped */ | |
320 | extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry); | |
321 | /* run all the marks in a group, and flag them to be freed */ | |
322 | extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); | |
323 | extern void fsnotify_get_mark(struct fsnotify_mark_entry *entry); | |
324 | extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry); | |
325 | ||
90586523 EP |
326 | /* put here because inotify does some weird stuff when destroying watches */ |
327 | extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, | |
47882c6f EP |
328 | void *data, int data_is, const char *name, |
329 | u32 cookie); | |
62ffe5df | 330 | |
90586523 EP |
331 | #else |
332 | ||
62ffe5df | 333 | static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
47882c6f | 334 | const char *name, u32 cookie) |
90586523 | 335 | {} |
3be25f49 | 336 | |
c28f7e56 EP |
337 | static inline void __fsnotify_parent(struct dentry *dentry, __u32 mask) |
338 | {} | |
339 | ||
3be25f49 EP |
340 | static inline void __fsnotify_inode_delete(struct inode *inode) |
341 | {} | |
342 | ||
c28f7e56 EP |
343 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) |
344 | {} | |
345 | ||
346 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) | |
347 | {} | |
348 | ||
47882c6f EP |
349 | static inline u32 fsnotify_get_cookie(void) |
350 | { | |
351 | return 0; | |
352 | } | |
353 | ||
90586523 EP |
354 | #endif /* CONFIG_FSNOTIFY */ |
355 | ||
356 | #endif /* __KERNEL __ */ | |
357 | ||
358 | #endif /* __LINUX_FSNOTIFY_BACKEND_H */ |