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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 | ||
ca9c726e AG |
39 | void __fsnotify_vfsmount_delete(struct vfsmount *mnt) |
40 | { | |
41 | fsnotify_clear_marks_by_mount(mnt); | |
42 | } | |
43 | ||
c28f7e56 EP |
44 | /* |
45 | * Given an inode, first check if we care what happens to our children. Inotify | |
46 | * and dnotify both tell their parents about events. If we care about any event | |
47 | * on a child we run all of our children and set a dentry flag saying that the | |
48 | * parent cares. Thus when an event happens on a child it can quickly tell if | |
49 | * if there is a need to find a parent and send the event to the parent. | |
50 | */ | |
51 | void __fsnotify_update_child_dentry_flags(struct inode *inode) | |
52 | { | |
53 | struct dentry *alias; | |
54 | int watched; | |
55 | ||
56 | if (!S_ISDIR(inode->i_mode)) | |
57 | return; | |
58 | ||
59 | /* determine if the children should tell inode about their events */ | |
60 | watched = fsnotify_inode_watches_children(inode); | |
61 | ||
62 | spin_lock(&dcache_lock); | |
63 | /* run all of the dentries associated with this inode. Since this is a | |
64 | * directory, there damn well better only be one item on this list */ | |
65 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { | |
66 | struct dentry *child; | |
67 | ||
68 | /* run all of the children of the original inode and fix their | |
69 | * d_flags to indicate parental interest (their parent is the | |
70 | * original inode) */ | |
71 | list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { | |
72 | if (!child->d_inode) | |
73 | continue; | |
74 | ||
75 | spin_lock(&child->d_lock); | |
76 | if (watched) | |
77 | child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; | |
78 | else | |
79 | child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
80 | spin_unlock(&child->d_lock); | |
81 | } | |
82 | } | |
83 | spin_unlock(&dcache_lock); | |
84 | } | |
85 | ||
86 | /* Notify this dentry's parent about a child's events. */ | |
72acc854 | 87 | void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) |
c28f7e56 EP |
88 | { |
89 | struct dentry *parent; | |
90 | struct inode *p_inode; | |
91 | bool send = false; | |
92 | bool should_update_children = false; | |
93 | ||
72acc854 AG |
94 | if (!dentry) |
95 | dentry = path->dentry; | |
28c60e37 | 96 | |
c28f7e56 EP |
97 | if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) |
98 | return; | |
99 | ||
100 | spin_lock(&dentry->d_lock); | |
101 | parent = dentry->d_parent; | |
102 | p_inode = parent->d_inode; | |
103 | ||
104 | if (fsnotify_inode_watches_children(p_inode)) { | |
105 | if (p_inode->i_fsnotify_mask & mask) { | |
106 | dget(parent); | |
107 | send = true; | |
108 | } | |
109 | } else { | |
110 | /* | |
111 | * The parent doesn't care about events on it's children but | |
112 | * at least one child thought it did. We need to run all the | |
113 | * children and update their d_flags to let them know p_inode | |
114 | * doesn't care about them any more. | |
115 | */ | |
116 | dget(parent); | |
117 | should_update_children = true; | |
118 | } | |
119 | ||
120 | spin_unlock(&dentry->d_lock); | |
121 | ||
122 | if (send) { | |
123 | /* we are notifying a parent so come up with the new mask which | |
124 | * specifies these are events which came from a child. */ | |
125 | mask |= FS_EVENT_ON_CHILD; | |
126 | ||
72acc854 AG |
127 | if (path) |
128 | fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, | |
28c60e37 EP |
129 | dentry->d_name.name, 0); |
130 | else | |
131 | fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, | |
132 | dentry->d_name.name, 0); | |
c28f7e56 EP |
133 | dput(parent); |
134 | } | |
135 | ||
136 | if (unlikely(should_update_children)) { | |
137 | __fsnotify_update_child_dentry_flags(p_inode); | |
138 | dput(parent); | |
139 | } | |
140 | } | |
141 | EXPORT_SYMBOL_GPL(__fsnotify_parent); | |
142 | ||
e8983861 EP |
143 | void __fsnotify_flush_ignored_mask(struct inode *inode, void *data, int data_is) |
144 | { | |
145 | struct fsnotify_mark *mark; | |
146 | struct hlist_node *node; | |
147 | ||
148 | if (!hlist_empty(&inode->i_fsnotify_marks)) { | |
149 | spin_lock(&inode->i_lock); | |
150 | hlist_for_each_entry(mark, node, &inode->i_fsnotify_marks, i.i_list) { | |
c908370f EP |
151 | if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) |
152 | mark->ignored_mask = 0; | |
e8983861 EP |
153 | } |
154 | spin_unlock(&inode->i_lock); | |
155 | } | |
156 | ||
157 | if (data_is == FSNOTIFY_EVENT_PATH) { | |
158 | struct vfsmount *mnt; | |
159 | ||
160 | mnt = ((struct path *)data)->mnt; | |
161 | if (mnt && !hlist_empty(&mnt->mnt_fsnotify_marks)) { | |
162 | spin_lock(&mnt->mnt_root->d_lock); | |
163 | hlist_for_each_entry(mark, node, &mnt->mnt_fsnotify_marks, m.m_list) { | |
c908370f EP |
164 | if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) |
165 | mark->ignored_mask = 0; | |
e8983861 EP |
166 | } |
167 | spin_unlock(&mnt->mnt_root->d_lock); | |
168 | } | |
169 | } | |
170 | } | |
171 | ||
c4ec54b4 EP |
172 | static int send_to_group(struct fsnotify_group *group, struct inode *to_tell, |
173 | struct vfsmount *mnt, __u32 mask, void *data, | |
174 | int data_is, u32 cookie, const unsigned char *file_name, | |
175 | struct fsnotify_event **event) | |
7131485a | 176 | { |
3a9fb89f | 177 | if (!group->ops->should_send_event(group, to_tell, mnt, mask, |
7131485a | 178 | data, data_is)) |
c4ec54b4 | 179 | return 0; |
7131485a EP |
180 | if (!*event) { |
181 | *event = fsnotify_create_event(to_tell, mask, data, | |
182 | data_is, file_name, | |
183 | cookie, GFP_KERNEL); | |
7131485a | 184 | if (!*event) |
c4ec54b4 | 185 | return -ENOMEM; |
7131485a | 186 | } |
c4ec54b4 | 187 | return group->ops->handle_event(group, *event); |
7131485a EP |
188 | } |
189 | ||
3a9fb89f | 190 | static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt) |
7131485a | 191 | { |
3a9fb89f | 192 | if (!mnt) |
7131485a EP |
193 | return false; |
194 | ||
2504c5d6 | 195 | return (test_mask & mnt->mnt_fsnotify_mask); |
7131485a | 196 | } |
e8983861 | 197 | |
90586523 EP |
198 | /* |
199 | * This is the main call to fsnotify. The VFS calls into hook specific functions | |
200 | * in linux/fsnotify.h. Those functions then in turn call here. Here will call | |
201 | * out to all of the registered fsnotify_group. Those groups can then use the | |
202 | * notification event in whatever means they feel necessary. | |
203 | */ | |
c4ec54b4 EP |
204 | int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
205 | const unsigned char *file_name, u32 cookie) | |
90586523 EP |
206 | { |
207 | struct fsnotify_group *group; | |
208 | struct fsnotify_event *event = NULL; | |
3a9fb89f | 209 | struct vfsmount *mnt = NULL; |
c4ec54b4 | 210 | int idx, ret = 0; |
e42e2773 EP |
211 | /* global tests shouldn't care about events on child only the specific event */ |
212 | __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); | |
90586523 | 213 | |
7131485a EP |
214 | /* if no fsnotify listeners, nothing to do */ |
215 | if (list_empty(&fsnotify_inode_groups) && | |
216 | list_empty(&fsnotify_vfsmount_groups)) | |
c4ec54b4 | 217 | return 0; |
7131485a | 218 | |
e8983861 EP |
219 | if (mask & FS_MODIFY) |
220 | __fsnotify_flush_ignored_mask(to_tell, data, data_is); | |
221 | ||
7131485a EP |
222 | /* if none of the directed listeners or vfsmount listeners care */ |
223 | if (!(test_mask & fsnotify_inode_mask) && | |
224 | !(test_mask & fsnotify_vfsmount_mask)) | |
c4ec54b4 | 225 | return 0; |
7131485a | 226 | |
3a9fb89f EP |
227 | if (data_is == FSNOTIFY_EVENT_PATH) |
228 | mnt = ((struct path *)data)->mnt; | |
3a9fb89f | 229 | |
7131485a EP |
230 | /* if this inode's directed listeners don't care and nothing on the vfsmount |
231 | * listeners list cares, nothing to do */ | |
232 | if (!(test_mask & to_tell->i_fsnotify_mask) && | |
3a9fb89f | 233 | !needed_by_vfsmount(test_mask, mnt)) |
c4ec54b4 | 234 | return 0; |
90586523 | 235 | |
90586523 EP |
236 | /* |
237 | * SRCU!! the groups list is very very much read only and the path is | |
238 | * very hot. The VAST majority of events are not going to need to do | |
239 | * anything other than walk the list so it's crazy to pre-allocate. | |
240 | */ | |
241 | idx = srcu_read_lock(&fsnotify_grp_srcu); | |
7131485a EP |
242 | |
243 | if (test_mask & to_tell->i_fsnotify_mask) { | |
244 | list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) { | |
245 | if (test_mask & group->mask) { | |
c4ec54b4 EP |
246 | ret = send_to_group(group, to_tell, NULL, mask, data, data_is, |
247 | cookie, file_name, &event); | |
248 | if (ret) | |
249 | goto out; | |
90586523 | 250 | } |
90586523 EP |
251 | } |
252 | } | |
3a9fb89f | 253 | if (needed_by_vfsmount(test_mask, mnt)) { |
7131485a EP |
254 | list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) { |
255 | if (test_mask & group->mask) { | |
c4ec54b4 EP |
256 | ret = send_to_group(group, to_tell, mnt, mask, data, data_is, |
257 | cookie, file_name, &event); | |
258 | if (ret) | |
259 | goto out; | |
7131485a EP |
260 | } |
261 | } | |
262 | } | |
c4ec54b4 | 263 | out: |
90586523 EP |
264 | srcu_read_unlock(&fsnotify_grp_srcu, idx); |
265 | /* | |
266 | * fsnotify_create_event() took a reference so the event can't be cleaned | |
267 | * up while we are still trying to add it to lists, drop that one. | |
268 | */ | |
269 | if (event) | |
270 | fsnotify_put_event(event); | |
c4ec54b4 | 271 | |
98b5c10d | 272 | return ret; |
90586523 EP |
273 | } |
274 | EXPORT_SYMBOL_GPL(fsnotify); | |
275 | ||
276 | static __init int fsnotify_init(void) | |
277 | { | |
20dee624 EP |
278 | BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); |
279 | ||
90586523 EP |
280 | return init_srcu_struct(&fsnotify_grp_srcu); |
281 | } | |
282 | subsys_initcall(fsnotify_init); |