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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> | |
24 | #include <linux/srcu.h> | |
25 | ||
26 | #include <linux/fsnotify_backend.h> | |
27 | #include "fsnotify.h" | |
28 | ||
3be25f49 EP |
29 | /* |
30 | * Clear all of the marks on an inode when it is being evicted from core | |
31 | */ | |
32 | void __fsnotify_inode_delete(struct inode *inode) | |
33 | { | |
34 | fsnotify_clear_marks_by_inode(inode); | |
35 | } | |
36 | EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); | |
37 | ||
c28f7e56 EP |
38 | /* |
39 | * Given an inode, first check if we care what happens to our children. Inotify | |
40 | * and dnotify both tell their parents about events. If we care about any event | |
41 | * on a child we run all of our children and set a dentry flag saying that the | |
42 | * parent cares. Thus when an event happens on a child it can quickly tell if | |
43 | * if there is a need to find a parent and send the event to the parent. | |
44 | */ | |
45 | void __fsnotify_update_child_dentry_flags(struct inode *inode) | |
46 | { | |
47 | struct dentry *alias; | |
48 | int watched; | |
49 | ||
50 | if (!S_ISDIR(inode->i_mode)) | |
51 | return; | |
52 | ||
53 | /* determine if the children should tell inode about their events */ | |
54 | watched = fsnotify_inode_watches_children(inode); | |
55 | ||
56 | spin_lock(&dcache_lock); | |
57 | /* run all of the dentries associated with this inode. Since this is a | |
58 | * directory, there damn well better only be one item on this list */ | |
59 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { | |
60 | struct dentry *child; | |
61 | ||
62 | /* run all of the children of the original inode and fix their | |
63 | * d_flags to indicate parental interest (their parent is the | |
64 | * original inode) */ | |
65 | list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { | |
66 | if (!child->d_inode) | |
67 | continue; | |
68 | ||
69 | spin_lock(&child->d_lock); | |
70 | if (watched) | |
71 | child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; | |
72 | else | |
73 | child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
74 | spin_unlock(&child->d_lock); | |
75 | } | |
76 | } | |
77 | spin_unlock(&dcache_lock); | |
78 | } | |
79 | ||
80 | /* Notify this dentry's parent about a child's events. */ | |
28c60e37 | 81 | void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask) |
c28f7e56 EP |
82 | { |
83 | struct dentry *parent; | |
84 | struct inode *p_inode; | |
85 | bool send = false; | |
86 | bool should_update_children = false; | |
87 | ||
28c60e37 EP |
88 | if (file) |
89 | dentry = file->f_path.dentry; | |
90 | ||
c28f7e56 EP |
91 | if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) |
92 | return; | |
93 | ||
94 | spin_lock(&dentry->d_lock); | |
95 | parent = dentry->d_parent; | |
96 | p_inode = parent->d_inode; | |
97 | ||
98 | if (fsnotify_inode_watches_children(p_inode)) { | |
99 | if (p_inode->i_fsnotify_mask & mask) { | |
100 | dget(parent); | |
101 | send = true; | |
102 | } | |
103 | } else { | |
104 | /* | |
105 | * The parent doesn't care about events on it's children but | |
106 | * at least one child thought it did. We need to run all the | |
107 | * children and update their d_flags to let them know p_inode | |
108 | * doesn't care about them any more. | |
109 | */ | |
110 | dget(parent); | |
111 | should_update_children = true; | |
112 | } | |
113 | ||
114 | spin_unlock(&dentry->d_lock); | |
115 | ||
116 | if (send) { | |
117 | /* we are notifying a parent so come up with the new mask which | |
118 | * specifies these are events which came from a child. */ | |
119 | mask |= FS_EVENT_ON_CHILD; | |
120 | ||
28c60e37 EP |
121 | if (file) |
122 | fsnotify(p_inode, mask, file, FSNOTIFY_EVENT_FILE, | |
123 | dentry->d_name.name, 0); | |
124 | else | |
125 | fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, | |
126 | dentry->d_name.name, 0); | |
c28f7e56 EP |
127 | dput(parent); |
128 | } | |
129 | ||
130 | if (unlikely(should_update_children)) { | |
131 | __fsnotify_update_child_dentry_flags(p_inode); | |
132 | dput(parent); | |
133 | } | |
134 | } | |
135 | EXPORT_SYMBOL_GPL(__fsnotify_parent); | |
136 | ||
90586523 EP |
137 | /* |
138 | * This is the main call to fsnotify. The VFS calls into hook specific functions | |
139 | * in linux/fsnotify.h. Those functions then in turn call here. Here will call | |
140 | * out to all of the registered fsnotify_group. Those groups can then use the | |
141 | * notification event in whatever means they feel necessary. | |
142 | */ | |
47882c6f | 143 | void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie) |
90586523 EP |
144 | { |
145 | struct fsnotify_group *group; | |
146 | struct fsnotify_event *event = NULL; | |
147 | int idx; | |
e42e2773 EP |
148 | /* global tests shouldn't care about events on child only the specific event */ |
149 | __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); | |
90586523 | 150 | |
19c2a0e1 | 151 | if (list_empty(&fsnotify_inode_groups)) |
90586523 EP |
152 | return; |
153 | ||
19c2a0e1 | 154 | if (!(test_mask & fsnotify_inode_mask)) |
90586523 EP |
155 | return; |
156 | ||
e42e2773 | 157 | if (!(test_mask & to_tell->i_fsnotify_mask)) |
3be25f49 | 158 | return; |
90586523 EP |
159 | /* |
160 | * SRCU!! the groups list is very very much read only and the path is | |
161 | * very hot. The VAST majority of events are not going to need to do | |
162 | * anything other than walk the list so it's crazy to pre-allocate. | |
163 | */ | |
164 | idx = srcu_read_lock(&fsnotify_grp_srcu); | |
19c2a0e1 | 165 | list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) { |
e42e2773 | 166 | if (test_mask & group->mask) { |
8112e2d6 EP |
167 | if (!group->ops->should_send_event(group, to_tell, mask, |
168 | data, data_is)) | |
3be25f49 | 169 | continue; |
90586523 | 170 | if (!event) { |
f44aebcc EP |
171 | event = fsnotify_create_event(to_tell, mask, data, |
172 | data_is, file_name, cookie, | |
173 | GFP_KERNEL); | |
90586523 EP |
174 | /* shit, we OOM'd and now we can't tell, maybe |
175 | * someday someone else will want to do something | |
176 | * here */ | |
177 | if (!event) | |
178 | break; | |
179 | } | |
180 | group->ops->handle_event(group, event); | |
181 | } | |
182 | } | |
183 | srcu_read_unlock(&fsnotify_grp_srcu, idx); | |
184 | /* | |
185 | * fsnotify_create_event() took a reference so the event can't be cleaned | |
186 | * up while we are still trying to add it to lists, drop that one. | |
187 | */ | |
188 | if (event) | |
189 | fsnotify_put_event(event); | |
190 | } | |
191 | EXPORT_SYMBOL_GPL(fsnotify); | |
192 | ||
193 | static __init int fsnotify_init(void) | |
194 | { | |
195 | return init_srcu_struct(&fsnotify_grp_srcu); | |
196 | } | |
197 | subsys_initcall(fsnotify_init); |