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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 | ||
3c5119c0 EP |
61 | /* listeners that hard code group numbers near the top */ |
62 | #define DNOTIFY_GROUP_NUM UINT_MAX | |
63c882a0 | 63 | #define INOTIFY_GROUP_NUM (DNOTIFY_GROUP_NUM-1) |
3c5119c0 | 64 | |
90586523 EP |
65 | struct fsnotify_group; |
66 | struct fsnotify_event; | |
3be25f49 | 67 | struct fsnotify_mark_entry; |
e4aff117 | 68 | struct fsnotify_event_private_data; |
90586523 EP |
69 | |
70 | /* | |
71 | * Each group much define these ops. The fsnotify infrastructure will call | |
72 | * these operations for each relevant group. | |
73 | * | |
3be25f49 EP |
74 | * should_send_event - given a group, inode, and mask this function determines |
75 | * if the group is interested in this event. | |
90586523 EP |
76 | * handle_event - main call for a group to handle an fs event |
77 | * free_group_priv - called when a group refcnt hits 0 to clean up the private union | |
3be25f49 EP |
78 | * freeing-mark - this means that a mark has been flagged to die when everything |
79 | * finishes using it. The function is supplied with what must be a | |
80 | * valid group and inode to use to clean up. | |
90586523 EP |
81 | */ |
82 | struct fsnotify_ops { | |
3be25f49 | 83 | bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, __u32 mask); |
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. | |
99 | * anchored by fsnotify_groups and protected by either fsnotify_grp_mutex | |
100 | * or fsnotify_grp_srcu depending on write vs read. | |
101 | */ | |
102 | struct list_head group_list; | |
103 | ||
104 | /* | |
105 | * Defines all of the event types in which this group is interested. | |
106 | * This mask is a bitwise OR of the FS_* events from above. Each time | |
107 | * this mask changes for a group (if it changes) the correct functions | |
108 | * must be called to update the global structures which indicate global | |
109 | * interest in event types. | |
110 | */ | |
111 | __u32 mask; | |
112 | ||
113 | /* | |
114 | * How the refcnt is used is up to each group. When the refcnt hits 0 | |
115 | * fsnotify will clean up all of the resources associated with this group. | |
116 | * As an example, the dnotify group will always have a refcnt=1 and that | |
117 | * will never change. Inotify, on the other hand, has a group per | |
118 | * inotify_init() and the refcnt will hit 0 only when that fd has been | |
119 | * closed. | |
120 | */ | |
121 | atomic_t refcnt; /* things with interest in this group */ | |
122 | unsigned int group_num; /* simply prevents accidental group collision */ | |
123 | ||
124 | const struct fsnotify_ops *ops; /* how this group handles things */ | |
125 | ||
a2d8bc6c EP |
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 */ | |
132 | ||
3be25f49 EP |
133 | /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */ |
134 | spinlock_t mark_lock; /* protect mark_entries list */ | |
135 | atomic_t num_marks; /* 1 for each mark entry and 1 for not being | |
136 | * past the point of no return when freeing | |
137 | * a group */ | |
138 | struct list_head mark_entries; /* all inode mark entries for this group */ | |
139 | ||
140 | /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */ | |
90586523 EP |
141 | bool on_group_list; |
142 | ||
143 | /* groups can define private fields here or use the void *private */ | |
144 | union { | |
145 | void *private; | |
63c882a0 EP |
146 | #ifdef CONFIG_INOTIFY_USER |
147 | struct inotify_group_private_data { | |
148 | spinlock_t idr_lock; | |
149 | struct idr idr; | |
150 | u32 last_wd; | |
151 | struct fasync_struct *fa; /* async notification */ | |
152 | struct user_struct *user; | |
153 | } inotify_data; | |
154 | #endif | |
90586523 EP |
155 | }; |
156 | }; | |
157 | ||
a2d8bc6c EP |
158 | /* |
159 | * A single event can be queued in multiple group->notification_lists. | |
160 | * | |
161 | * each group->notification_list will point to an event_holder which in turns points | |
162 | * to the actual event that needs to be sent to userspace. | |
163 | * | |
164 | * Seemed cheaper to create a refcnt'd event and a small holder for every group | |
165 | * than create a different event for every group | |
166 | * | |
167 | */ | |
168 | struct fsnotify_event_holder { | |
169 | struct fsnotify_event *event; | |
170 | struct list_head event_list; | |
171 | }; | |
172 | ||
e4aff117 EP |
173 | /* |
174 | * Inotify needs to tack data onto an event. This struct lets us later find the | |
175 | * correct private data of the correct group. | |
176 | */ | |
177 | struct fsnotify_event_private_data { | |
178 | struct fsnotify_group *group; | |
179 | struct list_head event_list; | |
180 | }; | |
181 | ||
90586523 EP |
182 | /* |
183 | * all of the information about the original object we want to now send to | |
184 | * a group. If you want to carry more info from the accessing task to the | |
185 | * listener this structure is where you need to be adding fields. | |
186 | */ | |
187 | struct fsnotify_event { | |
a2d8bc6c EP |
188 | /* |
189 | * If we create an event we are also likely going to need a holder | |
190 | * to link to a group. So embed one holder in the event. Means only | |
191 | * one allocation for the common case where we only have one group | |
192 | */ | |
193 | struct fsnotify_event_holder holder; | |
90586523 EP |
194 | spinlock_t lock; /* protection for the associated event_holder and private_list */ |
195 | /* to_tell may ONLY be dereferenced during handle_event(). */ | |
196 | struct inode *to_tell; /* either the inode the event happened to or its parent */ | |
197 | /* | |
198 | * depending on the event type we should have either a path or inode | |
199 | * We hold a reference on path, but NOT on inode. Since we have the ref on | |
200 | * the path, it may be dereferenced at any point during this object's | |
201 | * lifetime. That reference is dropped when this object's refcnt hits | |
202 | * 0. If this event contains an inode instead of a path, the inode may | |
203 | * ONLY be used during handle_event(). | |
204 | */ | |
205 | union { | |
206 | struct path path; | |
207 | struct inode *inode; | |
208 | }; | |
209 | /* when calling fsnotify tell it if the data is a path or inode */ | |
210 | #define FSNOTIFY_EVENT_NONE 0 | |
211 | #define FSNOTIFY_EVENT_PATH 1 | |
212 | #define FSNOTIFY_EVENT_INODE 2 | |
213 | #define FSNOTIFY_EVENT_FILE 3 | |
214 | int data_type; /* which of the above union we have */ | |
215 | atomic_t refcnt; /* how many groups still are using/need to send this event */ | |
216 | __u32 mask; /* the type of access, bitwise OR for FS_* event types */ | |
62ffe5df | 217 | |
47882c6f | 218 | u32 sync_cookie; /* used to corrolate events, namely inotify mv events */ |
62ffe5df EP |
219 | char *file_name; |
220 | size_t name_len; | |
e4aff117 EP |
221 | |
222 | struct list_head private_data_list; /* groups can store private data here */ | |
90586523 EP |
223 | }; |
224 | ||
3be25f49 EP |
225 | /* |
226 | * a mark is simply an entry attached to an in core inode which allows an | |
227 | * fsnotify listener to indicate they are either no longer interested in events | |
228 | * of a type matching mask or only interested in those events. | |
229 | * | |
230 | * these are flushed when an inode is evicted from core and may be flushed | |
231 | * when the inode is modified (as seen by fsnotify_access). Some fsnotify users | |
232 | * (such as dnotify) will flush these when the open fd is closed and not at | |
233 | * inode eviction or modification. | |
234 | */ | |
235 | struct fsnotify_mark_entry { | |
236 | __u32 mask; /* mask this mark entry is for */ | |
237 | /* we hold ref for each i_list and g_list. also one ref for each 'thing' | |
238 | * in kernel that found and may be using this mark. */ | |
239 | atomic_t refcnt; /* active things looking at this mark */ | |
240 | struct inode *inode; /* inode this entry is associated with */ | |
241 | struct fsnotify_group *group; /* group this mark entry is for */ | |
242 | struct hlist_node i_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */ | |
243 | struct list_head g_list; /* list of mark_entries by group->i_fsnotify_mark_entries */ | |
244 | spinlock_t lock; /* protect group, inode, and killme */ | |
245 | struct list_head free_i_list; /* tmp list used when freeing this mark */ | |
246 | struct list_head free_g_list; /* tmp list used when freeing this mark */ | |
247 | void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */ | |
248 | }; | |
249 | ||
90586523 EP |
250 | #ifdef CONFIG_FSNOTIFY |
251 | ||
252 | /* called from the vfs helpers */ | |
253 | ||
254 | /* main fsnotify call to send events */ | |
47882c6f EP |
255 | extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
256 | const char *name, u32 cookie); | |
c28f7e56 | 257 | extern void __fsnotify_parent(struct dentry *dentry, __u32 mask); |
3be25f49 | 258 | extern void __fsnotify_inode_delete(struct inode *inode); |
47882c6f | 259 | extern u32 fsnotify_get_cookie(void); |
90586523 | 260 | |
c28f7e56 EP |
261 | static inline int fsnotify_inode_watches_children(struct inode *inode) |
262 | { | |
263 | /* FS_EVENT_ON_CHILD is set if the inode may care */ | |
264 | if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) | |
265 | return 0; | |
266 | /* this inode might care about child events, does it care about the | |
267 | * specific set of events that can happen on a child? */ | |
268 | return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; | |
269 | } | |
270 | ||
271 | /* | |
272 | * Update the dentry with a flag indicating the interest of its parent to receive | |
273 | * filesystem events when those events happens to this dentry->d_inode. | |
274 | */ | |
275 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) | |
276 | { | |
277 | struct dentry *parent; | |
278 | ||
279 | assert_spin_locked(&dcache_lock); | |
280 | assert_spin_locked(&dentry->d_lock); | |
281 | ||
282 | parent = dentry->d_parent; | |
e6ce3066 | 283 | if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) |
c28f7e56 EP |
284 | dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; |
285 | else | |
286 | dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
287 | } | |
288 | ||
289 | /* | |
290 | * fsnotify_d_instantiate - instantiate a dentry for inode | |
291 | * Called with dcache_lock held. | |
292 | */ | |
293 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) | |
294 | { | |
295 | if (!inode) | |
296 | return; | |
297 | ||
298 | assert_spin_locked(&dcache_lock); | |
299 | ||
300 | spin_lock(&dentry->d_lock); | |
301 | __fsnotify_update_dcache_flags(dentry); | |
302 | spin_unlock(&dentry->d_lock); | |
303 | } | |
90586523 EP |
304 | |
305 | /* called from fsnotify listeners, such as fanotify or dnotify */ | |
306 | ||
307 | /* must call when a group changes its ->mask */ | |
308 | extern void fsnotify_recalc_global_mask(void); | |
309 | /* get a reference to an existing or create a new group */ | |
310 | extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, | |
311 | __u32 mask, | |
312 | const struct fsnotify_ops *ops); | |
3be25f49 EP |
313 | /* run all marks associated with this group and update group->mask */ |
314 | extern void fsnotify_recalc_group_mask(struct fsnotify_group *group); | |
90586523 EP |
315 | /* drop reference on a group from fsnotify_obtain_group */ |
316 | extern void fsnotify_put_group(struct fsnotify_group *group); | |
317 | ||
318 | /* take a reference to an event */ | |
319 | extern void fsnotify_get_event(struct fsnotify_event *event); | |
320 | extern void fsnotify_put_event(struct fsnotify_event *event); | |
e4aff117 EP |
321 | /* find private data previously attached to an event and unlink it */ |
322 | extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, | |
323 | struct fsnotify_event *event); | |
90586523 | 324 | |
a2d8bc6c | 325 | /* attach the event to the group notification queue */ |
e4aff117 EP |
326 | extern int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event, |
327 | struct fsnotify_event_private_data *priv); | |
a2d8bc6c EP |
328 | /* true if the group notification queue is empty */ |
329 | extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); | |
330 | /* return, but do not dequeue the first event on the notification queue */ | |
331 | extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); | |
e4aff117 | 332 | /* return AND dequeue the first event on the notification queue */ |
a2d8bc6c EP |
333 | extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); |
334 | ||
3be25f49 EP |
335 | /* functions used to manipulate the marks attached to inodes */ |
336 | ||
337 | /* run all marks associated with an inode and update inode->i_fsnotify_mask */ | |
338 | extern void fsnotify_recalc_inode_mask(struct inode *inode); | |
339 | extern void fsnotify_init_mark(struct fsnotify_mark_entry *entry, void (*free_mark)(struct fsnotify_mark_entry *entry)); | |
340 | /* find (and take a reference) to a mark associated with group and inode */ | |
341 | extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, struct inode *inode); | |
342 | /* attach the mark to both the group and the inode */ | |
343 | extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode); | |
344 | /* given a mark, flag it to be freed when all references are dropped */ | |
345 | extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry); | |
346 | /* run all the marks in a group, and flag them to be freed */ | |
347 | extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); | |
348 | extern void fsnotify_get_mark(struct fsnotify_mark_entry *entry); | |
349 | extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry); | |
164bc619 | 350 | extern void fsnotify_unmount_inodes(struct list_head *list); |
3be25f49 | 351 | |
90586523 EP |
352 | /* put here because inotify does some weird stuff when destroying watches */ |
353 | extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, | |
47882c6f | 354 | void *data, int data_is, const char *name, |
f44aebcc | 355 | u32 cookie, gfp_t gfp); |
62ffe5df | 356 | |
90586523 EP |
357 | #else |
358 | ||
62ffe5df | 359 | static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
47882c6f | 360 | const char *name, u32 cookie) |
90586523 | 361 | {} |
3be25f49 | 362 | |
c28f7e56 EP |
363 | static inline void __fsnotify_parent(struct dentry *dentry, __u32 mask) |
364 | {} | |
365 | ||
3be25f49 EP |
366 | static inline void __fsnotify_inode_delete(struct inode *inode) |
367 | {} | |
368 | ||
c28f7e56 EP |
369 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) |
370 | {} | |
371 | ||
372 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) | |
373 | {} | |
374 | ||
47882c6f EP |
375 | static inline u32 fsnotify_get_cookie(void) |
376 | { | |
377 | return 0; | |
378 | } | |
379 | ||
164bc619 EP |
380 | static inline void fsnotify_unmount_inodes(struct list_head *list) |
381 | {} | |
382 | ||
90586523 EP |
383 | #endif /* CONFIG_FSNOTIFY */ |
384 | ||
385 | #endif /* __KERNEL __ */ | |
386 | ||
387 | #endif /* __LINUX_FSNOTIFY_BACKEND_H */ |