]> bbs.cooldavid.org Git - net-next-2.6.git/blame - fs/notify/fsnotify.c
fsnotify: fix ignored mask handling between inode and vfsmount marks
[net-next-2.6.git] / fs / notify / fsnotify.c
CommitLineData
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1/*
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>
5a0e3ad6 21#include <linux/gfp.h>
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22#include <linux/init.h>
23#include <linux/module.h>
7131485a 24#include <linux/mount.h>
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25#include <linux/srcu.h>
26
27#include <linux/fsnotify_backend.h>
28#include "fsnotify.h"
29
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30/*
31 * 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
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39void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
40{
41 fsnotify_clear_marks_by_mount(mnt);
42}
43
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44/*
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.
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. */
2069601b 87void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
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88{
89 struct dentry *parent;
90 struct inode *p_inode;
91 bool send = false;
92 bool should_update_children = false;
93
72acc854 94 if (!dentry)
2069601b 95 dentry = path->dentry;
28c60e37 96
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97 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
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127 if (path)
128 fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
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129 dentry->d_name.name, 0);
130 else
131 fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
132 dentry->d_name.name, 0);
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133 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
613a807f 143static int send_to_group(struct inode *to_tell, struct vfsmount *mnt,
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144 struct fsnotify_mark *inode_mark,
145 struct fsnotify_mark *vfsmount_mark,
146 __u32 mask, void *data,
613a807f 147 int data_is, u32 cookie,
3a9b16b4 148 const unsigned char *file_name,
c4ec54b4 149 struct fsnotify_event **event)
7131485a 150{
faa9560a 151 struct fsnotify_group *group = NULL;
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152 __u32 inode_test_mask = 0;
153 __u32 vfsmount_test_mask = 0;
613a807f 154
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155 if (unlikely(!inode_mark && !vfsmount_mark)) {
156 BUG();
157 return 0;
158 }
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159
160 /* clear ignored on inode modification */
161 if (mask & FS_MODIFY) {
162 if (inode_mark &&
163 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
164 inode_mark->ignored_mask = 0;
165 if (vfsmount_mark &&
166 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
167 vfsmount_mark->ignored_mask = 0;
168 }
5ba08e2e 169
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170 /* does the inode mark tell us to do something? */
171 if (inode_mark) {
faa9560a 172 group = inode_mark->group;
84e1ab4d 173 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
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174 inode_test_mask &= inode_mark->mask;
175 inode_test_mask &= ~inode_mark->ignored_mask;
176 }
613a807f 177
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178 /* does the vfsmount_mark tell us to do something? */
179 if (vfsmount_mark) {
84e1ab4d 180 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
faa9560a 181 group = vfsmount_mark->group;
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182 vfsmount_test_mask &= vfsmount_mark->mask;
183 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
184 if (inode_mark)
185 vfsmount_test_mask &= ~inode_mark->ignored_mask;
186 }
187
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188 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p"
189 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
190 " data=%p data_is=%d cookie=%d event=%p\n",
191 __func__, group, to_tell, mnt, mask, inode_mark,
192 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
193 data_is, cookie, *event);
faa9560a 194
ce8f76fb 195 if (!inode_test_mask && !vfsmount_test_mask)
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196 return 0;
197
1968f5ee 198 if (group->ops->should_send_event(group, to_tell, inode_mark,
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199 vfsmount_mark, mask, data,
200 data_is) == false)
c4ec54b4 201 return 0;
613a807f 202
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203 if (!*event) {
204 *event = fsnotify_create_event(to_tell, mask, data,
205 data_is, file_name,
206 cookie, GFP_KERNEL);
7131485a 207 if (!*event)
c4ec54b4 208 return -ENOMEM;
7131485a 209 }
ce8f76fb 210 return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event);
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211}
212
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213/*
214 * This is the main call to fsnotify. The VFS calls into hook specific functions
215 * in linux/fsnotify.h. Those functions then in turn call here. Here will call
216 * out to all of the registered fsnotify_group. Those groups can then use the
217 * notification event in whatever means they feel necessary.
218 */
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219int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
220 const unsigned char *file_name, u32 cookie)
90586523 221{
84e1ab4d 222 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
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223 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
224 struct fsnotify_group *inode_group, *vfsmount_group;
90586523 225 struct fsnotify_event *event = NULL;
613a807f 226 struct vfsmount *mnt;
c4ec54b4 227 int idx, ret = 0;
5f3f259f 228 bool used_inode, used_vfsmount;
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229 /* global tests shouldn't care about events on child only the specific event */
230 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
90586523 231
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232 if (data_is == FSNOTIFY_EVENT_PATH)
233 mnt = ((struct path *)data)->mnt;
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234 else
235 mnt = NULL;
236
237 /*
238 * if this is a modify event we may need to clear the ignored masks
239 * otherwise return if neither the inode nor the vfsmount care about
240 * this type of event.
241 */
242 if (!(mask & FS_MODIFY) &&
243 !(test_mask & to_tell->i_fsnotify_mask) &&
244 !(mnt && test_mask & mnt->mnt_fsnotify_mask))
245 return 0;
3a9fb89f 246
75c1be48 247 idx = srcu_read_lock(&fsnotify_mark_srcu);
7131485a 248
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249 if ((mask & FS_MODIFY) ||
250 (test_mask & to_tell->i_fsnotify_mask))
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251 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
252 &fsnotify_mark_srcu);
613a807f 253
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254 if (mnt && ((mask & FS_MODIFY) ||
255 (test_mask & mnt->mnt_fsnotify_mask))) {
256 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
257 &fsnotify_mark_srcu);
258 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
259 &fsnotify_mark_srcu);
90586523 260 }
75c1be48 261
613a807f 262 while (inode_node || vfsmount_node) {
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263 used_inode = used_vfsmount = false;
264
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265 if (inode_node) {
266 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
267 struct fsnotify_mark, i.i_list);
268 inode_group = inode_mark->group;
269 } else
270 inode_group = (void *)-1;
271
272 if (vfsmount_node) {
273 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
274 struct fsnotify_mark, m.m_list);
275 vfsmount_group = vfsmount_mark->group;
276 } else
277 vfsmount_group = (void *)-1;
278
279 if (inode_group < vfsmount_group) {
280 /* handle inode */
ce8f76fb 281 send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
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282 data_is, cookie, file_name, &event);
283 used_inode = true;
284 } else if (vfsmount_group < inode_group) {
ce8f76fb 285 send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
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286 data_is, cookie, file_name, &event);
287 used_vfsmount = true;
288 } else {
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289 send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
290 mask, data, data_is, cookie, file_name,
291 &event);
613a807f 292 used_vfsmount = true;
613a807f 293 used_inode = true;
7131485a 294 }
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295
296 if (used_inode)
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297 inode_node = srcu_dereference(inode_node->next,
298 &fsnotify_mark_srcu);
613a807f 299 if (used_vfsmount)
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300 vfsmount_node = srcu_dereference(vfsmount_node->next,
301 &fsnotify_mark_srcu);
7131485a 302 }
613a807f 303
75c1be48 304 srcu_read_unlock(&fsnotify_mark_srcu, idx);
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305 /*
306 * fsnotify_create_event() took a reference so the event can't be cleaned
307 * up while we are still trying to add it to lists, drop that one.
308 */
309 if (event)
310 fsnotify_put_event(event);
c4ec54b4 311
98b5c10d 312 return ret;
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313}
314EXPORT_SYMBOL_GPL(fsnotify);
315
316static __init int fsnotify_init(void)
317{
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318 int ret;
319
20dee624
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320 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
321
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322 ret = init_srcu_struct(&fsnotify_mark_srcu);
323 if (ret)
324 panic("initializing fsnotify_mark_srcu");
325
326 return 0;
90586523 327}
75c1be48 328core_initcall(fsnotify_init);