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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 | ||
49 | struct fsnotify_group; | |
50 | struct fsnotify_event; | |
3be25f49 | 51 | struct fsnotify_mark_entry; |
90586523 EP |
52 | |
53 | /* | |
54 | * Each group much define these ops. The fsnotify infrastructure will call | |
55 | * these operations for each relevant group. | |
56 | * | |
3be25f49 EP |
57 | * should_send_event - given a group, inode, and mask this function determines |
58 | * if the group is interested in this event. | |
90586523 EP |
59 | * handle_event - main call for a group to handle an fs event |
60 | * free_group_priv - called when a group refcnt hits 0 to clean up the private union | |
3be25f49 EP |
61 | * freeing-mark - this means that a mark has been flagged to die when everything |
62 | * finishes using it. The function is supplied with what must be a | |
63 | * valid group and inode to use to clean up. | |
90586523 EP |
64 | */ |
65 | struct fsnotify_ops { | |
3be25f49 | 66 | bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, __u32 mask); |
90586523 EP |
67 | int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event); |
68 | void (*free_group_priv)(struct fsnotify_group *group); | |
3be25f49 | 69 | void (*freeing_mark)(struct fsnotify_mark_entry *entry, struct fsnotify_group *group); |
90586523 EP |
70 | }; |
71 | ||
72 | /* | |
73 | * A group is a "thing" that wants to receive notification about filesystem | |
74 | * events. The mask holds the subset of event types this group cares about. | |
75 | * refcnt on a group is up to the implementor and at any moment if it goes 0 | |
76 | * everything will be cleaned up. | |
77 | */ | |
78 | struct fsnotify_group { | |
79 | /* | |
80 | * global list of all groups receiving events from fsnotify. | |
81 | * anchored by fsnotify_groups and protected by either fsnotify_grp_mutex | |
82 | * or fsnotify_grp_srcu depending on write vs read. | |
83 | */ | |
84 | struct list_head group_list; | |
85 | ||
86 | /* | |
87 | * Defines all of the event types in which this group is interested. | |
88 | * This mask is a bitwise OR of the FS_* events from above. Each time | |
89 | * this mask changes for a group (if it changes) the correct functions | |
90 | * must be called to update the global structures which indicate global | |
91 | * interest in event types. | |
92 | */ | |
93 | __u32 mask; | |
94 | ||
95 | /* | |
96 | * How the refcnt is used is up to each group. When the refcnt hits 0 | |
97 | * fsnotify will clean up all of the resources associated with this group. | |
98 | * As an example, the dnotify group will always have a refcnt=1 and that | |
99 | * will never change. Inotify, on the other hand, has a group per | |
100 | * inotify_init() and the refcnt will hit 0 only when that fd has been | |
101 | * closed. | |
102 | */ | |
103 | atomic_t refcnt; /* things with interest in this group */ | |
104 | unsigned int group_num; /* simply prevents accidental group collision */ | |
105 | ||
106 | const struct fsnotify_ops *ops; /* how this group handles things */ | |
107 | ||
3be25f49 EP |
108 | /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */ |
109 | spinlock_t mark_lock; /* protect mark_entries list */ | |
110 | atomic_t num_marks; /* 1 for each mark entry and 1 for not being | |
111 | * past the point of no return when freeing | |
112 | * a group */ | |
113 | struct list_head mark_entries; /* all inode mark entries for this group */ | |
114 | ||
115 | /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */ | |
90586523 EP |
116 | bool on_group_list; |
117 | ||
118 | /* groups can define private fields here or use the void *private */ | |
119 | union { | |
120 | void *private; | |
121 | }; | |
122 | }; | |
123 | ||
124 | /* | |
125 | * all of the information about the original object we want to now send to | |
126 | * a group. If you want to carry more info from the accessing task to the | |
127 | * listener this structure is where you need to be adding fields. | |
128 | */ | |
129 | struct fsnotify_event { | |
130 | spinlock_t lock; /* protection for the associated event_holder and private_list */ | |
131 | /* to_tell may ONLY be dereferenced during handle_event(). */ | |
132 | struct inode *to_tell; /* either the inode the event happened to or its parent */ | |
133 | /* | |
134 | * depending on the event type we should have either a path or inode | |
135 | * We hold a reference on path, but NOT on inode. Since we have the ref on | |
136 | * the path, it may be dereferenced at any point during this object's | |
137 | * lifetime. That reference is dropped when this object's refcnt hits | |
138 | * 0. If this event contains an inode instead of a path, the inode may | |
139 | * ONLY be used during handle_event(). | |
140 | */ | |
141 | union { | |
142 | struct path path; | |
143 | struct inode *inode; | |
144 | }; | |
145 | /* when calling fsnotify tell it if the data is a path or inode */ | |
146 | #define FSNOTIFY_EVENT_NONE 0 | |
147 | #define FSNOTIFY_EVENT_PATH 1 | |
148 | #define FSNOTIFY_EVENT_INODE 2 | |
149 | #define FSNOTIFY_EVENT_FILE 3 | |
150 | int data_type; /* which of the above union we have */ | |
151 | atomic_t refcnt; /* how many groups still are using/need to send this event */ | |
152 | __u32 mask; /* the type of access, bitwise OR for FS_* event types */ | |
153 | }; | |
154 | ||
3be25f49 EP |
155 | /* |
156 | * a mark is simply an entry attached to an in core inode which allows an | |
157 | * fsnotify listener to indicate they are either no longer interested in events | |
158 | * of a type matching mask or only interested in those events. | |
159 | * | |
160 | * these are flushed when an inode is evicted from core and may be flushed | |
161 | * when the inode is modified (as seen by fsnotify_access). Some fsnotify users | |
162 | * (such as dnotify) will flush these when the open fd is closed and not at | |
163 | * inode eviction or modification. | |
164 | */ | |
165 | struct fsnotify_mark_entry { | |
166 | __u32 mask; /* mask this mark entry is for */ | |
167 | /* we hold ref for each i_list and g_list. also one ref for each 'thing' | |
168 | * in kernel that found and may be using this mark. */ | |
169 | atomic_t refcnt; /* active things looking at this mark */ | |
170 | struct inode *inode; /* inode this entry is associated with */ | |
171 | struct fsnotify_group *group; /* group this mark entry is for */ | |
172 | struct hlist_node i_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */ | |
173 | struct list_head g_list; /* list of mark_entries by group->i_fsnotify_mark_entries */ | |
174 | spinlock_t lock; /* protect group, inode, and killme */ | |
175 | struct list_head free_i_list; /* tmp list used when freeing this mark */ | |
176 | struct list_head free_g_list; /* tmp list used when freeing this mark */ | |
177 | void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */ | |
178 | }; | |
179 | ||
90586523 EP |
180 | #ifdef CONFIG_FSNOTIFY |
181 | ||
182 | /* called from the vfs helpers */ | |
183 | ||
184 | /* main fsnotify call to send events */ | |
185 | extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is); | |
3be25f49 | 186 | extern void __fsnotify_inode_delete(struct inode *inode); |
90586523 EP |
187 | |
188 | ||
189 | /* called from fsnotify listeners, such as fanotify or dnotify */ | |
190 | ||
191 | /* must call when a group changes its ->mask */ | |
192 | extern void fsnotify_recalc_global_mask(void); | |
193 | /* get a reference to an existing or create a new group */ | |
194 | extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, | |
195 | __u32 mask, | |
196 | const struct fsnotify_ops *ops); | |
3be25f49 EP |
197 | /* run all marks associated with this group and update group->mask */ |
198 | extern void fsnotify_recalc_group_mask(struct fsnotify_group *group); | |
90586523 EP |
199 | /* drop reference on a group from fsnotify_obtain_group */ |
200 | extern void fsnotify_put_group(struct fsnotify_group *group); | |
201 | ||
202 | /* take a reference to an event */ | |
203 | extern void fsnotify_get_event(struct fsnotify_event *event); | |
204 | extern void fsnotify_put_event(struct fsnotify_event *event); | |
205 | /* find private data previously attached to an event */ | |
206 | extern struct fsnotify_event_private_data *fsnotify_get_priv_from_event(struct fsnotify_group *group, | |
207 | struct fsnotify_event *event); | |
208 | ||
3be25f49 EP |
209 | /* functions used to manipulate the marks attached to inodes */ |
210 | ||
211 | /* run all marks associated with an inode and update inode->i_fsnotify_mask */ | |
212 | extern void fsnotify_recalc_inode_mask(struct inode *inode); | |
213 | extern void fsnotify_init_mark(struct fsnotify_mark_entry *entry, void (*free_mark)(struct fsnotify_mark_entry *entry)); | |
214 | /* find (and take a reference) to a mark associated with group and inode */ | |
215 | extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, struct inode *inode); | |
216 | /* attach the mark to both the group and the inode */ | |
217 | extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode); | |
218 | /* given a mark, flag it to be freed when all references are dropped */ | |
219 | extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry); | |
220 | /* run all the marks in a group, and flag them to be freed */ | |
221 | extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); | |
222 | extern void fsnotify_get_mark(struct fsnotify_mark_entry *entry); | |
223 | extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry); | |
224 | ||
90586523 EP |
225 | /* put here because inotify does some weird stuff when destroying watches */ |
226 | extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, | |
227 | void *data, int data_is); | |
228 | #else | |
229 | ||
230 | static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is) | |
231 | {} | |
3be25f49 EP |
232 | |
233 | static inline void __fsnotify_inode_delete(struct inode *inode) | |
234 | {} | |
235 | ||
90586523 EP |
236 | #endif /* CONFIG_FSNOTIFY */ |
237 | ||
238 | #endif /* __KERNEL __ */ | |
239 | ||
240 | #endif /* __LINUX_FSNOTIFY_BACKEND_H */ |