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/srcu.h>
26 #include <linux/fsnotify_backend.h>
30 * Clear all of the marks on an inode when it is being evicted from core
32 void __fsnotify_inode_delete(struct inode *inode)
34 fsnotify_clear_marks_by_inode(inode);
36 EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
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.
45 void __fsnotify_update_child_dentry_flags(struct inode *inode)
50 if (!S_ISDIR(inode->i_mode))
53 /* determine if the children should tell inode about their events */
54 watched = fsnotify_inode_watches_children(inode);
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) {
62 /* run all of the children of the original inode and fix their
63 * d_flags to indicate parental interest (their parent is the
65 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
69 spin_lock(&child->d_lock);
71 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
73 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
74 spin_unlock(&child->d_lock);
77 spin_unlock(&dcache_lock);
80 /* Notify this dentry's parent about a child's events. */
81 void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
83 struct dentry *parent;
84 struct inode *p_inode;
86 bool should_update_children = false;
89 dentry = file->f_path.dentry;
91 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
94 spin_lock(&dentry->d_lock);
95 parent = dentry->d_parent;
96 p_inode = parent->d_inode;
98 if (fsnotify_inode_watches_children(p_inode)) {
99 if (p_inode->i_fsnotify_mask & mask) {
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.
111 should_update_children = true;
114 spin_unlock(&dentry->d_lock);
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;
122 fsnotify(p_inode, mask, file, FSNOTIFY_EVENT_FILE,
123 dentry->d_name.name, 0);
125 fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
126 dentry->d_name.name, 0);
130 if (unlikely(should_update_children)) {
131 __fsnotify_update_child_dentry_flags(p_inode);
135 EXPORT_SYMBOL_GPL(__fsnotify_parent);
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.
143 void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie)
145 struct fsnotify_group *group;
146 struct fsnotify_event *event = NULL;
148 /* global tests shouldn't care about events on child only the specific event */
149 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
151 if (list_empty(&fsnotify_groups))
154 if (!(test_mask & fsnotify_mask))
157 if (!(test_mask & to_tell->i_fsnotify_mask))
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.
164 idx = srcu_read_lock(&fsnotify_grp_srcu);
165 list_for_each_entry_rcu(group, &fsnotify_groups, group_list) {
166 if (test_mask & group->mask) {
167 if (!group->ops->should_send_event(group, to_tell, mask,
171 event = fsnotify_create_event(to_tell, mask, data,
172 data_is, file_name, cookie,
174 /* shit, we OOM'd and now we can't tell, maybe
175 * someday someone else will want to do something
180 group->ops->handle_event(group, event);
183 srcu_read_unlock(&fsnotify_grp_srcu, idx);
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.
189 fsnotify_put_event(event);
191 EXPORT_SYMBOL_GPL(fsnotify);
193 static __init int fsnotify_init(void)
195 return init_srcu_struct(&fsnotify_grp_srcu);
197 subsys_initcall(fsnotify_init);