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/fs.h> /* struct inode */
26 #include <linux/fsnotify_backend.h>
27 #include <linux/inotify.h>
28 #include <linux/path.h> /* struct path */
29 #include <linux/slab.h> /* kmem_* */
30 #include <linux/types.h>
31
32 #include "inotify.h"
33
34 static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
35 {
36 struct fsnotify_mark_entry *entry;
37 struct inotify_inode_mark_entry *ientry;
38 struct inode *to_tell;
39 struct inotify_event_private_data *event_priv;
40 struct fsnotify_event_private_data *fsn_event_priv;
41 int wd, ret;
42
43 to_tell = event->to_tell;
44
45 spin_lock(&to_tell->i_lock);
46 entry = fsnotify_find_mark_entry(group, to_tell);
47 spin_unlock(&to_tell->i_lock);
48 /* race with watch removal? We already passes should_send */
49 if (unlikely(!entry))
50 return 0;
51 ientry = container_of(entry, struct inotify_inode_mark_entry,
52 fsn_entry);
53 wd = ientry->wd;
54
55 event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
56 if (unlikely(!event_priv))
57 return -ENOMEM;
58
59 fsn_event_priv = &event_priv->fsnotify_event_priv_data;
60
61 fsn_event_priv->group = group;
62 event_priv->wd = wd;
63
64 ret = fsnotify_add_notify_event(group, event, fsn_event_priv);
65 if (ret) {
66 inotify_free_event_priv(fsn_event_priv);
67 /* EEXIST says we tail matched, EOVERFLOW isn't something
68 * to report up the stack. */
69 if ((ret == -EEXIST) ||
70 (ret == -EOVERFLOW))
71 ret = 0;
72 }
73
74 /*
75 * If we hold the entry until after the event is on the queue
76 * IN_IGNORED won't be able to pass this event in the queue
77 */
78 fsnotify_put_mark(entry);
79
80 return ret;
81 }
82
83 static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
84 {
85 inotify_ignored_and_remove_idr(entry, group);
86 }
87
88 static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
89 {
90 struct fsnotify_mark_entry *entry;
91 bool send;
92
93 spin_lock(&inode->i_lock);
94 entry = fsnotify_find_mark_entry(group, inode);
95 spin_unlock(&inode->i_lock);
96 if (!entry)
97 return false;
98
99 mask = (mask & ~FS_EVENT_ON_CHILD);
100 send = (entry->mask & mask);
101
102 /* find took a reference */
103 fsnotify_put_mark(entry);
104
105 return send;
106 }
107
108 /*
109 * This is NEVER supposed to be called. Inotify marks should either have been
110 * removed from the idr when the watch was removed or in the
111 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
112 * torn down. This is only called if the idr is about to be freed but there
113 * are still marks in it.
114 */
115 static int idr_callback(int id, void *p, void *data)
116 {
117 struct fsnotify_mark_entry *entry;
118 struct inotify_inode_mark_entry *ientry;
119 static bool warned = false;
120
121 if (warned)
122 return 0;
123
124 warned = true;
125 entry = p;
126 ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
127
128 WARN(1, "inotify closing but id=%d for entry=%p in group=%p still in "
129 "idr. Probably leaking memory\n", id, p, data);
130
131 /*
132 * I'm taking the liberty of assuming that the mark in question is a
133 * valid address and I'm dereferencing it. This might help to figure
134 * out why we got here and the panic is no worse than the original
135 * BUG() that was here.
136 */
137 if (entry)
138 printk(KERN_WARNING "entry->group=%p inode=%p wd=%d\n",
139 entry->group, entry->inode, ientry->wd);
140 return 0;
141 }
142
143 static void inotify_free_group_priv(struct fsnotify_group *group)
144 {
145 /* ideally the idr is empty and we won't hit the BUG in teh callback */
146 idr_for_each(&group->inotify_data.idr, idr_callback, group);
147 idr_remove_all(&group->inotify_data.idr);
148 idr_destroy(&group->inotify_data.idr);
149 }
150
151 void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
152 {
153 struct inotify_event_private_data *event_priv;
154
155
156 event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
157 fsnotify_event_priv_data);
158
159 kmem_cache_free(event_priv_cachep, event_priv);
160 }
161
162 const struct fsnotify_ops inotify_fsnotify_ops = {
163 .handle_event = inotify_handle_event,
164 .should_send_event = inotify_should_send_event,
165 .free_group_priv = inotify_free_group_priv,
166 .free_event_priv = inotify_free_event_priv,
167 .freeing_mark = inotify_freeing_mark,
168 };
169
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