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90586523 EP |
1 | /* |
2 | * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2, or (at your option) | |
7 | * any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; see the file COPYING. If not, write to | |
16 | * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
17 | */ | |
18 | ||
19 | #include <linux/dcache.h> | |
20 | #include <linux/fs.h> | |
5a0e3ad6 | 21 | #include <linux/gfp.h> |
90586523 EP |
22 | #include <linux/init.h> |
23 | #include <linux/module.h> | |
7131485a | 24 | #include <linux/mount.h> |
90586523 EP |
25 | #include <linux/srcu.h> |
26 | ||
27 | #include <linux/fsnotify_backend.h> | |
28 | #include "fsnotify.h" | |
29 | ||
3be25f49 EP |
30 | /* |
31 | * Clear all of the marks on an inode when it is being evicted from core | |
32 | */ | |
33 | void __fsnotify_inode_delete(struct inode *inode) | |
34 | { | |
35 | fsnotify_clear_marks_by_inode(inode); | |
36 | } | |
37 | EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); | |
38 | ||
c28f7e56 EP |
39 | /* |
40 | * Given an inode, first check if we care what happens to our children. Inotify | |
41 | * and dnotify both tell their parents about events. If we care about any event | |
42 | * on a child we run all of our children and set a dentry flag saying that the | |
43 | * parent cares. Thus when an event happens on a child it can quickly tell if | |
44 | * if there is a need to find a parent and send the event to the parent. | |
45 | */ | |
46 | void __fsnotify_update_child_dentry_flags(struct inode *inode) | |
47 | { | |
48 | struct dentry *alias; | |
49 | int watched; | |
50 | ||
51 | if (!S_ISDIR(inode->i_mode)) | |
52 | return; | |
53 | ||
54 | /* determine if the children should tell inode about their events */ | |
55 | watched = fsnotify_inode_watches_children(inode); | |
56 | ||
57 | spin_lock(&dcache_lock); | |
58 | /* run all of the dentries associated with this inode. Since this is a | |
59 | * directory, there damn well better only be one item on this list */ | |
60 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { | |
61 | struct dentry *child; | |
62 | ||
63 | /* run all of the children of the original inode and fix their | |
64 | * d_flags to indicate parental interest (their parent is the | |
65 | * original inode) */ | |
66 | list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { | |
67 | if (!child->d_inode) | |
68 | continue; | |
69 | ||
70 | spin_lock(&child->d_lock); | |
71 | if (watched) | |
72 | child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; | |
73 | else | |
74 | child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
75 | spin_unlock(&child->d_lock); | |
76 | } | |
77 | } | |
78 | spin_unlock(&dcache_lock); | |
79 | } | |
80 | ||
81 | /* Notify this dentry's parent about a child's events. */ | |
28c60e37 | 82 | void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask) |
c28f7e56 EP |
83 | { |
84 | struct dentry *parent; | |
85 | struct inode *p_inode; | |
86 | bool send = false; | |
87 | bool should_update_children = false; | |
88 | ||
28c60e37 EP |
89 | if (file) |
90 | dentry = file->f_path.dentry; | |
91 | ||
c28f7e56 EP |
92 | if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) |
93 | return; | |
94 | ||
95 | spin_lock(&dentry->d_lock); | |
96 | parent = dentry->d_parent; | |
97 | p_inode = parent->d_inode; | |
98 | ||
99 | if (fsnotify_inode_watches_children(p_inode)) { | |
100 | if (p_inode->i_fsnotify_mask & mask) { | |
101 | dget(parent); | |
102 | send = true; | |
103 | } | |
104 | } else { | |
105 | /* | |
106 | * The parent doesn't care about events on it's children but | |
107 | * at least one child thought it did. We need to run all the | |
108 | * children and update their d_flags to let them know p_inode | |
109 | * doesn't care about them any more. | |
110 | */ | |
111 | dget(parent); | |
112 | should_update_children = true; | |
113 | } | |
114 | ||
115 | spin_unlock(&dentry->d_lock); | |
116 | ||
117 | if (send) { | |
118 | /* we are notifying a parent so come up with the new mask which | |
119 | * specifies these are events which came from a child. */ | |
120 | mask |= FS_EVENT_ON_CHILD; | |
121 | ||
28c60e37 EP |
122 | if (file) |
123 | fsnotify(p_inode, mask, file, FSNOTIFY_EVENT_FILE, | |
124 | dentry->d_name.name, 0); | |
125 | else | |
126 | fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, | |
127 | dentry->d_name.name, 0); | |
c28f7e56 EP |
128 | dput(parent); |
129 | } | |
130 | ||
131 | if (unlikely(should_update_children)) { | |
132 | __fsnotify_update_child_dentry_flags(p_inode); | |
133 | dput(parent); | |
134 | } | |
135 | } | |
136 | EXPORT_SYMBOL_GPL(__fsnotify_parent); | |
137 | ||
7131485a EP |
138 | static void send_to_group(__u32 mask, |
139 | struct fsnotify_group *group, | |
140 | void *data, int data_is, const char *file_name, | |
141 | u32 cookie, struct fsnotify_event **event, | |
142 | struct inode *to_tell) | |
143 | { | |
144 | if (!group->ops->should_send_event(group, to_tell, mask, | |
145 | data, data_is)) | |
146 | return; | |
147 | if (!*event) { | |
148 | *event = fsnotify_create_event(to_tell, mask, data, | |
149 | data_is, file_name, | |
150 | cookie, GFP_KERNEL); | |
151 | /* | |
152 | * shit, we OOM'd and now we can't tell, maybe | |
153 | * someday someone else will want to do something | |
154 | * here | |
155 | */ | |
156 | if (!*event) | |
157 | return; | |
158 | } | |
159 | group->ops->handle_event(group, *event); | |
160 | } | |
161 | ||
162 | static bool needed_by_vfsmount(__u32 test_mask, void *data, int data_is) | |
163 | { | |
164 | struct path *path; | |
165 | ||
166 | if (data_is == FSNOTIFY_EVENT_PATH) | |
167 | path = (struct path *)data; | |
168 | else if (data_is == FSNOTIFY_EVENT_FILE) | |
169 | path = &((struct file *)data)->f_path; | |
170 | else | |
171 | return false; | |
172 | ||
173 | /* hook in this when mnt->mnt_fsnotify_mask is defined */ | |
174 | /* return (test_mask & path->mnt->mnt_fsnotify_mask); */ | |
175 | return false; | |
176 | } | |
90586523 EP |
177 | /* |
178 | * This is the main call to fsnotify. The VFS calls into hook specific functions | |
179 | * in linux/fsnotify.h. Those functions then in turn call here. Here will call | |
180 | * out to all of the registered fsnotify_group. Those groups can then use the | |
181 | * notification event in whatever means they feel necessary. | |
182 | */ | |
47882c6f | 183 | void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie) |
90586523 EP |
184 | { |
185 | struct fsnotify_group *group; | |
186 | struct fsnotify_event *event = NULL; | |
187 | int idx; | |
e42e2773 EP |
188 | /* global tests shouldn't care about events on child only the specific event */ |
189 | __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); | |
90586523 | 190 | |
7131485a EP |
191 | /* if no fsnotify listeners, nothing to do */ |
192 | if (list_empty(&fsnotify_inode_groups) && | |
193 | list_empty(&fsnotify_vfsmount_groups)) | |
194 | return; | |
195 | ||
196 | /* if none of the directed listeners or vfsmount listeners care */ | |
197 | if (!(test_mask & fsnotify_inode_mask) && | |
198 | !(test_mask & fsnotify_vfsmount_mask)) | |
199 | return; | |
200 | ||
201 | /* if this inode's directed listeners don't care and nothing on the vfsmount | |
202 | * listeners list cares, nothing to do */ | |
203 | if (!(test_mask & to_tell->i_fsnotify_mask) && | |
204 | !needed_by_vfsmount(test_mask, data, data_is)) | |
205 | return; | |
90586523 | 206 | |
90586523 EP |
207 | /* |
208 | * SRCU!! the groups list is very very much read only and the path is | |
209 | * very hot. The VAST majority of events are not going to need to do | |
210 | * anything other than walk the list so it's crazy to pre-allocate. | |
211 | */ | |
212 | idx = srcu_read_lock(&fsnotify_grp_srcu); | |
7131485a EP |
213 | |
214 | if (test_mask & to_tell->i_fsnotify_mask) { | |
215 | list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) { | |
216 | if (test_mask & group->mask) { | |
217 | send_to_group(mask, group, data, data_is, | |
218 | file_name, cookie, &event, to_tell); | |
90586523 | 219 | } |
90586523 EP |
220 | } |
221 | } | |
7131485a EP |
222 | if (needed_by_vfsmount(test_mask, data, data_is)) { |
223 | list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) { | |
224 | if (test_mask & group->mask) { | |
225 | send_to_group(mask, group, data, data_is, | |
226 | file_name, cookie, &event, to_tell); | |
227 | } | |
228 | } | |
229 | } | |
230 | ||
90586523 EP |
231 | srcu_read_unlock(&fsnotify_grp_srcu, idx); |
232 | /* | |
233 | * fsnotify_create_event() took a reference so the event can't be cleaned | |
234 | * up while we are still trying to add it to lists, drop that one. | |
235 | */ | |
236 | if (event) | |
237 | fsnotify_put_event(event); | |
238 | } | |
239 | EXPORT_SYMBOL_GPL(fsnotify); | |
240 | ||
241 | static __init int fsnotify_init(void) | |
242 | { | |
243 | return init_srcu_struct(&fsnotify_grp_srcu); | |
244 | } | |
245 | subsys_initcall(fsnotify_init); |