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1/*
2 * fs/inotify_user.c - inotify support for userspace
3 *
4 * Authors:
5 * John McCutchan <ttb@tentacle.dhs.org>
6 * Robert Love <rml@novell.com>
7 *
8 * Copyright (C) 2005 John McCutchan
9 * Copyright 2006 Hewlett-Packard Development Company, L.P.
10 *
11 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
12 * inotify was largely rewriten to make use of the fsnotify infrastructure
13 *
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License as published by the
16 * Free Software Foundation; either version 2, or (at your option) any
17 * later version.
18 *
19 * This program is distributed in the hope that it will be useful, but
20 * WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * General Public License for more details.
23 */
24
25#include <linux/dcache.h> /* d_unlinked */
26#include <linux/fs.h> /* struct inode */
27#include <linux/fsnotify_backend.h>
28#include <linux/inotify.h>
29#include <linux/path.h> /* struct path */
30#include <linux/slab.h> /* kmem_* */
31#include <linux/types.h>
32#include <linux/sched.h>
33
34#include "inotify.h"
35
36/*
37 * Check if 2 events contain the same information. We do not compare private data
38 * but at this moment that isn't a problem for any know fsnotify listeners.
39 */
40static bool event_compare(struct fsnotify_event *old, struct fsnotify_event *new)
41{
42 if ((old->mask == new->mask) &&
43 (old->to_tell == new->to_tell) &&
44 (old->data_type == new->data_type) &&
45 (old->name_len == new->name_len)) {
46 switch (old->data_type) {
47 case (FSNOTIFY_EVENT_INODE):
48 /* remember, after old was put on the wait_q we aren't
49 * allowed to look at the inode any more, only thing
50 * left to check was if the file_name is the same */
51 if (!old->name_len ||
52 !strcmp(old->file_name, new->file_name))
53 return true;
54 break;
55 case (FSNOTIFY_EVENT_PATH):
56 if ((old->path.mnt == new->path.mnt) &&
57 (old->path.dentry == new->path.dentry))
58 return true;
59 break;
60 case (FSNOTIFY_EVENT_NONE):
61 if (old->mask & FS_Q_OVERFLOW)
62 return true;
63 else if (old->mask & FS_IN_IGNORED)
64 return false;
65 return true;
66 };
67 }
68 return false;
69}
70
71static struct fsnotify_event *inotify_merge(struct list_head *list,
72 struct fsnotify_event *event)
73{
74 struct fsnotify_event_holder *last_holder;
75 struct fsnotify_event *last_event;
76
77 /* and the list better be locked by something too */
78 spin_lock(&event->lock);
79
80 last_holder = list_entry(list->prev, struct fsnotify_event_holder, event_list);
81 last_event = last_holder->event;
82 if (event_compare(last_event, event))
83 fsnotify_get_event(last_event);
84 else
85 last_event = NULL;
86
87 spin_unlock(&event->lock);
88
89 return last_event;
90}
91
92static int inotify_handle_event(struct fsnotify_group *group,
93 struct fsnotify_mark *inode_mark,
94 struct fsnotify_mark *vfsmount_mark,
95 struct fsnotify_event *event)
96{
97 struct inotify_inode_mark *i_mark;
98 struct inode *to_tell;
99 struct inotify_event_private_data *event_priv;
100 struct fsnotify_event_private_data *fsn_event_priv;
101 struct fsnotify_event *added_event;
102 int wd, ret = 0;
103
104 BUG_ON(vfsmount_mark);
105
106 pr_debug("%s: group=%p event=%p to_tell=%p mask=%x\n", __func__, group,
107 event, event->to_tell, event->mask);
108
109 to_tell = event->to_tell;
110
111 i_mark = container_of(inode_mark, struct inotify_inode_mark,
112 fsn_mark);
113 wd = i_mark->wd;
114
115 event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
116 if (unlikely(!event_priv))
117 return -ENOMEM;
118
119 fsn_event_priv = &event_priv->fsnotify_event_priv_data;
120
121 fsn_event_priv->group = group;
122 event_priv->wd = wd;
123
124 added_event = fsnotify_add_notify_event(group, event, fsn_event_priv, inotify_merge);
125 if (added_event) {
126 inotify_free_event_priv(fsn_event_priv);
127 if (!IS_ERR(added_event))
128 fsnotify_put_event(added_event);
129 else
130 ret = PTR_ERR(added_event);
131 }
132
133 if (inode_mark->mask & IN_ONESHOT)
134 fsnotify_destroy_mark(inode_mark);
135
136 return ret;
137}
138
139static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
140{
141 inotify_ignored_and_remove_idr(fsn_mark, group);
142}
143
144static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode,
145 struct fsnotify_mark *inode_mark,
146 struct fsnotify_mark *vfsmount_mark,
147 __u32 mask, void *data, int data_type)
148{
149 if ((inode_mark->mask & FS_EXCL_UNLINK) &&
150 (data_type == FSNOTIFY_EVENT_PATH)) {
151 struct path *path = data;
152
153 if (d_unlinked(path->dentry))
154 return false;
155 }
156
157 return true;
158}
159
160/*
161 * This is NEVER supposed to be called. Inotify marks should either have been
162 * removed from the idr when the watch was removed or in the
163 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
164 * torn down. This is only called if the idr is about to be freed but there
165 * are still marks in it.
166 */
167static int idr_callback(int id, void *p, void *data)
168{
169 struct fsnotify_mark *fsn_mark;
170 struct inotify_inode_mark *i_mark;
171 static bool warned = false;
172
173 if (warned)
174 return 0;
175
176 warned = true;
177 fsn_mark = p;
178 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
179
180 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
181 "idr. Probably leaking memory\n", id, p, data);
182
183 /*
184 * I'm taking the liberty of assuming that the mark in question is a
185 * valid address and I'm dereferencing it. This might help to figure
186 * out why we got here and the panic is no worse than the original
187 * BUG() that was here.
188 */
189 if (fsn_mark)
190 printk(KERN_WARNING "fsn_mark->group=%p inode=%p wd=%d\n",
191 fsn_mark->group, fsn_mark->i.inode, i_mark->wd);
192 return 0;
193}
194
195static void inotify_free_group_priv(struct fsnotify_group *group)
196{
197 /* ideally the idr is empty and we won't hit the BUG in the callback */
198 idr_for_each(&group->inotify_data.idr, idr_callback, group);
199 idr_remove_all(&group->inotify_data.idr);
200 idr_destroy(&group->inotify_data.idr);
201 atomic_dec(&group->inotify_data.user->inotify_devs);
202 free_uid(group->inotify_data.user);
203}
204
205void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
206{
207 struct inotify_event_private_data *event_priv;
208
209
210 event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
211 fsnotify_event_priv_data);
212
213 kmem_cache_free(event_priv_cachep, event_priv);
214}
215
216const struct fsnotify_ops inotify_fsnotify_ops = {
217 .handle_event = inotify_handle_event,
218 .should_send_event = inotify_should_send_event,
219 .free_group_priv = inotify_free_group_priv,
220 .free_event_priv = inotify_free_event_priv,
221 .freeing_mark = inotify_freeing_mark,
222};