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(&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) {
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 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
75 spin_lock(&child->d_lock);
77 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
79 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
80 spin_unlock(&child->d_lock);
83 spin_unlock(&dcache_lock);
86 /* Notify this dentry's parent about a child's events. */
87 void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
89 struct dentry *parent;
90 struct inode *p_inode;
92 bool should_update_children = false;
95 dentry = path->dentry;
97 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
100 spin_lock(&dentry->d_lock);
101 parent = dentry->d_parent;
102 p_inode = parent->d_inode;
104 if (fsnotify_inode_watches_children(p_inode)) {
105 if (p_inode->i_fsnotify_mask & mask) {
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.
117 should_update_children = true;
120 spin_unlock(&dentry->d_lock);
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;
128 fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
129 dentry->d_name.name, 0);
131 fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
132 dentry->d_name.name, 0);
136 if (unlikely(should_update_children)) {
137 __fsnotify_update_child_dentry_flags(p_inode);
141 EXPORT_SYMBOL_GPL(__fsnotify_parent);
143 static void send_to_group(struct fsnotify_group *group, struct inode *to_tell,
144 struct vfsmount *mnt, __u32 mask, void *data,
145 int data_is, u32 cookie, const char *file_name,
146 struct fsnotify_event **event)
148 if (!group->ops->should_send_event(group, to_tell, mnt, mask,
152 *event = fsnotify_create_event(to_tell, mask, data,
156 * shit, we OOM'd and now we can't tell, maybe
157 * someday someone else will want to do something
163 group->ops->handle_event(group, *event);
166 static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt)
171 return (test_mask & mnt->mnt_fsnotify_mask);
174 * This is the main call to fsnotify. The VFS calls into hook specific functions
175 * in linux/fsnotify.h. Those functions then in turn call here. Here will call
176 * out to all of the registered fsnotify_group. Those groups can then use the
177 * notification event in whatever means they feel necessary.
179 void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie)
181 struct fsnotify_group *group;
182 struct fsnotify_event *event = NULL;
183 struct vfsmount *mnt = NULL;
185 /* global tests shouldn't care about events on child only the specific event */
186 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
188 /* if no fsnotify listeners, nothing to do */
189 if (list_empty(&fsnotify_inode_groups) &&
190 list_empty(&fsnotify_vfsmount_groups))
193 /* if none of the directed listeners or vfsmount listeners care */
194 if (!(test_mask & fsnotify_inode_mask) &&
195 !(test_mask & fsnotify_vfsmount_mask))
198 if (data_is == FSNOTIFY_EVENT_PATH)
199 mnt = ((struct path *)data)->mnt;
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, mnt))
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.
212 idx = srcu_read_lock(&fsnotify_grp_srcu);
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(group, to_tell, NULL, mask, data, data_is,
218 cookie, file_name, &event);
222 if (needed_by_vfsmount(test_mask, mnt)) {
223 list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) {
224 if (test_mask & group->mask) {
225 send_to_group(group, to_tell, mnt, mask, data, data_is,
226 cookie, file_name, &event);
231 srcu_read_unlock(&fsnotify_grp_srcu, idx);
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.
237 fsnotify_put_event(event);
239 EXPORT_SYMBOL_GPL(fsnotify);
241 static __init int fsnotify_init(void)
243 return init_srcu_struct(&fsnotify_grp_srcu);
245 subsys_initcall(fsnotify_init);