2 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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)
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.
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.
19 #include <linux/dcache.h>
21 #include <linux/gfp.h>
22 #include <linux/init.h>
23 #include <linux/module.h>
24 #include <linux/mount.h>
25 #include <linux/srcu.h>
27 #include <linux/fsnotify_backend.h>
31 * Clear all of the marks on an inode when it is being evicted from core
33 void __fsnotify_inode_delete(struct inode *inode)
35 fsnotify_clear_marks_by_inode(inode);
37 EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
39 void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
41 fsnotify_clear_marks_by_mount(mnt);
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.
51 void __fsnotify_update_child_dentry_flags(struct inode *inode)
56 if (!S_ISDIR(inode->i_mode))
59 /* determine if the children should tell inode about their events */
60 watched = fsnotify_inode_watches_children(inode);
62 spin_lock(&inode->i_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 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
68 /* run all of the children of the original inode and fix their
69 * d_flags to indicate parental interest (their parent is the
71 spin_lock(&alias->d_lock);
72 list_for_each_entry(child, &alias->d_subdirs, d_child) {
76 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
78 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
80 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
81 spin_unlock(&child->d_lock);
83 spin_unlock(&alias->d_lock);
85 spin_unlock(&inode->i_lock);
88 /* Notify this dentry's parent about a child's events. */
89 int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
91 struct dentry *parent;
92 struct inode *p_inode;
96 dentry = path->dentry;
98 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
101 parent = dget_parent(dentry);
102 p_inode = parent->d_inode;
104 if (unlikely(!fsnotify_inode_watches_children(p_inode)))
105 __fsnotify_update_child_dentry_flags(p_inode);
106 else if (p_inode->i_fsnotify_mask & mask) {
107 /* we are notifying a parent so come up with the new mask which
108 * specifies these are events which came from a child. */
109 mask |= FS_EVENT_ON_CHILD;
112 ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
113 dentry->d_name.name, 0);
115 ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
116 dentry->d_name.name, 0);
123 EXPORT_SYMBOL_GPL(__fsnotify_parent);
125 static int send_to_group(struct inode *to_tell,
126 struct fsnotify_mark *inode_mark,
127 struct fsnotify_mark *vfsmount_mark,
128 __u32 mask, const void *data,
129 int data_is, u32 cookie,
130 const unsigned char *file_name)
132 struct fsnotify_group *group = NULL;
133 __u32 inode_test_mask = 0;
134 __u32 vfsmount_test_mask = 0;
136 if (unlikely(!inode_mark && !vfsmount_mark)) {
141 /* clear ignored on inode modification */
142 if (mask & FS_MODIFY) {
144 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
145 inode_mark->ignored_mask = 0;
147 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
148 vfsmount_mark->ignored_mask = 0;
151 /* does the inode mark tell us to do something? */
153 group = inode_mark->group;
154 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
155 inode_test_mask &= inode_mark->mask;
156 inode_test_mask &= ~inode_mark->ignored_mask;
159 /* does the vfsmount_mark tell us to do something? */
161 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
162 group = vfsmount_mark->group;
163 vfsmount_test_mask &= vfsmount_mark->mask;
164 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
166 vfsmount_test_mask &= ~inode_mark->ignored_mask;
169 pr_debug("%s: group=%p to_tell=%p mask=%x inode_mark=%p"
170 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
171 " data=%p data_is=%d cookie=%d\n",
172 __func__, group, to_tell, mask, inode_mark,
173 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
176 if (!inode_test_mask && !vfsmount_test_mask)
179 return group->ops->handle_event(group, to_tell, inode_mark,
180 vfsmount_mark, mask, data, data_is,
185 * This is the main call to fsnotify. The VFS calls into hook specific functions
186 * in linux/fsnotify.h. Those functions then in turn call here. Here will call
187 * out to all of the registered fsnotify_group. Those groups can then use the
188 * notification event in whatever means they feel necessary.
190 int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
191 const unsigned char *file_name, u32 cookie)
193 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
194 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
195 struct fsnotify_group *inode_group, *vfsmount_group;
196 struct fsnotify_mark_connector *inode_conn, *vfsmount_conn;
199 /* global tests shouldn't care about events on child only the specific event */
200 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
202 if (data_is == FSNOTIFY_EVENT_PATH)
203 mnt = real_mount(((const struct path *)data)->mnt);
208 * Optimization: srcu_read_lock() has a memory barrier which can
209 * be expensive. It protects walking the *_fsnotify_marks lists.
210 * However, if we do not walk the lists, we do not have to do
211 * SRCU because we have no references to any objects and do not
212 * need SRCU to keep them "alive".
214 if (!to_tell->i_fsnotify_marks &&
215 (!mnt || !mnt->mnt_fsnotify_marks))
218 * if this is a modify event we may need to clear the ignored masks
219 * otherwise return if neither the inode nor the vfsmount care about
220 * this type of event.
222 if (!(mask & FS_MODIFY) &&
223 !(test_mask & to_tell->i_fsnotify_mask) &&
224 !(mnt && test_mask & mnt->mnt_fsnotify_mask))
227 idx = srcu_read_lock(&fsnotify_mark_srcu);
229 if ((mask & FS_MODIFY) ||
230 (test_mask & to_tell->i_fsnotify_mask)) {
231 inode_conn = srcu_dereference(to_tell->i_fsnotify_marks,
232 &fsnotify_mark_srcu);
234 inode_node = srcu_dereference(inode_conn->list.first,
235 &fsnotify_mark_srcu);
238 if (mnt && ((mask & FS_MODIFY) ||
239 (test_mask & mnt->mnt_fsnotify_mask))) {
240 inode_conn = srcu_dereference(to_tell->i_fsnotify_marks,
241 &fsnotify_mark_srcu);
243 inode_node = srcu_dereference(inode_conn->list.first,
244 &fsnotify_mark_srcu);
245 vfsmount_conn = srcu_dereference(mnt->mnt_fsnotify_marks,
246 &fsnotify_mark_srcu);
248 vfsmount_node = srcu_dereference(
249 vfsmount_conn->list.first,
250 &fsnotify_mark_srcu);
254 * We need to merge inode & vfsmount mark lists so that inode mark
255 * ignore masks are properly reflected for mount mark notifications.
256 * That's why this traversal is so complicated...
258 while (inode_node || vfsmount_node) {
261 vfsmount_group = NULL;
262 vfsmount_mark = NULL;
265 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
266 struct fsnotify_mark, obj_list);
267 inode_group = inode_mark->group;
271 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
272 struct fsnotify_mark, obj_list);
273 vfsmount_group = vfsmount_mark->group;
276 if (inode_group && vfsmount_group) {
277 int cmp = fsnotify_compare_groups(inode_group,
282 } else if (cmp < 0) {
283 vfsmount_group = NULL;
284 vfsmount_mark = NULL;
287 ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask,
288 data, data_is, cookie, file_name);
290 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
294 inode_node = srcu_dereference(inode_node->next,
295 &fsnotify_mark_srcu);
297 vfsmount_node = srcu_dereference(vfsmount_node->next,
298 &fsnotify_mark_srcu);
302 srcu_read_unlock(&fsnotify_mark_srcu, idx);
306 EXPORT_SYMBOL_GPL(fsnotify);
308 extern struct kmem_cache *fsnotify_mark_connector_cachep;
310 static __init int fsnotify_init(void)
314 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
316 ret = init_srcu_struct(&fsnotify_mark_srcu);
318 panic("initializing fsnotify_mark_srcu");
320 fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector,
325 core_initcall(fsnotify_init);