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Eric Paris90586522009-05-21 17:01:20 -04001/*
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090021#include <linux/gfp.h>
Eric Paris90586522009-05-21 17:01:20 -040022#include <linux/init.h>
23#include <linux/module.h>
Eric Paris71314852009-12-17 21:24:23 -050024#include <linux/mount.h>
Eric Paris90586522009-05-21 17:01:20 -040025#include <linux/srcu.h>
26
27#include <linux/fsnotify_backend.h>
28#include "fsnotify.h"
29
30/*
Eric Paris3be25f42009-05-21 17:01:26 -040031 * Clear all of the marks on an inode when it is being evicted from core
32 */
33void __fsnotify_inode_delete(struct inode *inode)
34{
35 fsnotify_clear_marks_by_inode(inode);
36}
37EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
38
Andreas Gruenbacherca9c7262009-12-17 21:24:27 -050039void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
40{
41 fsnotify_clear_marks_by_mount(mnt);
42}
43
Eric Paris3be25f42009-05-21 17:01:26 -040044/*
Eric Parisc28f7e52009-05-21 17:01:29 -040045 * 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 */
51void __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. */
Andreas Gruenbacher72acc852009-12-17 21:24:24 -050087void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
Eric Parisc28f7e52009-05-21 17:01:29 -040088{
89 struct dentry *parent;
90 struct inode *p_inode;
91 bool send = false;
92 bool should_update_children = false;
93
Andreas Gruenbacher72acc852009-12-17 21:24:24 -050094 if (!dentry)
95 dentry = path->dentry;
Eric Paris28c60e32009-12-17 21:24:21 -050096
Eric Parisc28f7e52009-05-21 17:01:29 -040097 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
Andreas Gruenbacher72acc852009-12-17 21:24:24 -0500127 if (path)
128 fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
Eric Paris28c60e32009-12-17 21:24:21 -0500129 dentry->d_name.name, 0);
130 else
131 fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
132 dentry->d_name.name, 0);
Eric Parisc28f7e52009-05-21 17:01:29 -0400133 dput(parent);
134 }
135
136 if (unlikely(should_update_children)) {
137 __fsnotify_update_child_dentry_flags(p_inode);
138 dput(parent);
139 }
140}
141EXPORT_SYMBOL_GPL(__fsnotify_parent);
142
Eric Parise8983862009-12-17 21:24:33 -0500143void __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) {
Eric Parisc9083702009-12-17 21:24:33 -0500151 if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
152 mark->ignored_mask = 0;
Eric Parise8983862009-12-17 21:24:33 -0500153 }
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) {
Eric Parisc9083702009-12-17 21:24:33 -0500164 if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
165 mark->ignored_mask = 0;
Eric Parise8983862009-12-17 21:24:33 -0500166 }
167 spin_unlock(&mnt->mnt_root->d_lock);
168 }
169 }
170}
171
Eric Parisc4ec54b2009-12-17 21:24:34 -0500172static 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)
Eric Paris71314852009-12-17 21:24:23 -0500176{
Eric Paris5ba08e22010-07-28 10:18:37 -0400177 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_is=%d"
178 " cookie=%d event=%p\n", __func__, group, to_tell, mnt,
179 mask, data, data_is, cookie, *event);
180
Eric Paris3a9fb892009-12-17 21:24:23 -0500181 if (!group->ops->should_send_event(group, to_tell, mnt, mask,
Eric Paris71314852009-12-17 21:24:23 -0500182 data, data_is))
Eric Parisc4ec54b2009-12-17 21:24:34 -0500183 return 0;
Eric Paris71314852009-12-17 21:24:23 -0500184 if (!*event) {
185 *event = fsnotify_create_event(to_tell, mask, data,
186 data_is, file_name,
187 cookie, GFP_KERNEL);
Eric Paris71314852009-12-17 21:24:23 -0500188 if (!*event)
Eric Parisc4ec54b2009-12-17 21:24:34 -0500189 return -ENOMEM;
Eric Paris71314852009-12-17 21:24:23 -0500190 }
Eric Parisc4ec54b2009-12-17 21:24:34 -0500191 return group->ops->handle_event(group, *event);
Eric Paris71314852009-12-17 21:24:23 -0500192}
193
Eric Paris3a9fb892009-12-17 21:24:23 -0500194static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt)
Eric Paris71314852009-12-17 21:24:23 -0500195{
Eric Paris3a9fb892009-12-17 21:24:23 -0500196 if (!mnt)
Eric Paris71314852009-12-17 21:24:23 -0500197 return false;
198
Andreas Gruenbacher2504c5d2009-12-17 21:24:27 -0500199 return (test_mask & mnt->mnt_fsnotify_mask);
Eric Paris71314852009-12-17 21:24:23 -0500200}
Eric Parise8983862009-12-17 21:24:33 -0500201
Eric Parisc28f7e52009-05-21 17:01:29 -0400202/*
Eric Paris90586522009-05-21 17:01:20 -0400203 * This is the main call to fsnotify. The VFS calls into hook specific functions
204 * in linux/fsnotify.h. Those functions then in turn call here. Here will call
205 * out to all of the registered fsnotify_group. Those groups can then use the
206 * notification event in whatever means they feel necessary.
207 */
Eric Parisc4ec54b2009-12-17 21:24:34 -0500208int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
209 const unsigned char *file_name, u32 cookie)
Eric Paris90586522009-05-21 17:01:20 -0400210{
211 struct fsnotify_group *group;
212 struct fsnotify_event *event = NULL;
Eric Paris3a9fb892009-12-17 21:24:23 -0500213 struct vfsmount *mnt = NULL;
Eric Parisc4ec54b2009-12-17 21:24:34 -0500214 int idx, ret = 0;
Eric Parise42e2772009-06-11 11:09:47 -0400215 /* global tests shouldn't care about events on child only the specific event */
216 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
Eric Paris90586522009-05-21 17:01:20 -0400217
Eric Paris71314852009-12-17 21:24:23 -0500218 /* if no fsnotify listeners, nothing to do */
219 if (list_empty(&fsnotify_inode_groups) &&
220 list_empty(&fsnotify_vfsmount_groups))
Eric Parisc4ec54b2009-12-17 21:24:34 -0500221 return 0;
Eric Paris71314852009-12-17 21:24:23 -0500222
Eric Parise8983862009-12-17 21:24:33 -0500223 if (mask & FS_MODIFY)
224 __fsnotify_flush_ignored_mask(to_tell, data, data_is);
225
Eric Paris71314852009-12-17 21:24:23 -0500226 /* if none of the directed listeners or vfsmount listeners care */
227 if (!(test_mask & fsnotify_inode_mask) &&
228 !(test_mask & fsnotify_vfsmount_mask))
Eric Parisc4ec54b2009-12-17 21:24:34 -0500229 return 0;
Eric Paris71314852009-12-17 21:24:23 -0500230
Eric Paris3a9fb892009-12-17 21:24:23 -0500231 if (data_is == FSNOTIFY_EVENT_PATH)
232 mnt = ((struct path *)data)->mnt;
Eric Paris3a9fb892009-12-17 21:24:23 -0500233
Eric Paris71314852009-12-17 21:24:23 -0500234 /* if this inode's directed listeners don't care and nothing on the vfsmount
235 * listeners list cares, nothing to do */
236 if (!(test_mask & to_tell->i_fsnotify_mask) &&
Eric Paris3a9fb892009-12-17 21:24:23 -0500237 !needed_by_vfsmount(test_mask, mnt))
Eric Parisc4ec54b2009-12-17 21:24:34 -0500238 return 0;
Eric Paris90586522009-05-21 17:01:20 -0400239
Eric Paris90586522009-05-21 17:01:20 -0400240 /*
241 * SRCU!! the groups list is very very much read only and the path is
242 * very hot. The VAST majority of events are not going to need to do
243 * anything other than walk the list so it's crazy to pre-allocate.
244 */
245 idx = srcu_read_lock(&fsnotify_grp_srcu);
Eric Paris71314852009-12-17 21:24:23 -0500246
247 if (test_mask & to_tell->i_fsnotify_mask) {
248 list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) {
249 if (test_mask & group->mask) {
Eric Parisc4ec54b2009-12-17 21:24:34 -0500250 ret = send_to_group(group, to_tell, NULL, mask, data, data_is,
251 cookie, file_name, &event);
252 if (ret)
253 goto out;
Eric Paris90586522009-05-21 17:01:20 -0400254 }
Eric Paris90586522009-05-21 17:01:20 -0400255 }
256 }
Eric Paris3a9fb892009-12-17 21:24:23 -0500257 if (needed_by_vfsmount(test_mask, mnt)) {
Eric Paris71314852009-12-17 21:24:23 -0500258 list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) {
259 if (test_mask & group->mask) {
Eric Parisc4ec54b2009-12-17 21:24:34 -0500260 ret = send_to_group(group, to_tell, mnt, mask, data, data_is,
261 cookie, file_name, &event);
262 if (ret)
263 goto out;
Eric Paris71314852009-12-17 21:24:23 -0500264 }
265 }
266 }
Eric Parisc4ec54b2009-12-17 21:24:34 -0500267out:
Eric Paris90586522009-05-21 17:01:20 -0400268 srcu_read_unlock(&fsnotify_grp_srcu, idx);
269 /*
270 * fsnotify_create_event() took a reference so the event can't be cleaned
271 * up while we are still trying to add it to lists, drop that one.
272 */
273 if (event)
274 fsnotify_put_event(event);
Eric Parisc4ec54b2009-12-17 21:24:34 -0500275
Jean-Christophe Dubois98b5c102010-03-23 08:08:09 +0100276 return ret;
Eric Paris90586522009-05-21 17:01:20 -0400277}
278EXPORT_SYMBOL_GPL(fsnotify);
279
280static __init int fsnotify_init(void)
281{
Eric Paris20dee622010-07-28 10:18:37 -0400282 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
283
Eric Paris90586522009-05-21 17:01:20 -0400284 return init_srcu_struct(&fsnotify_grp_srcu);
285}
286subsys_initcall(fsnotify_init);