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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>
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>
26
27#include <linux/fsnotify_backend.h>
28#include "fsnotify.h"
29#include "../mount.h"
30
31/*
32 * Clear all of the marks on an inode when it is being evicted from core
33 */
34void __fsnotify_inode_delete(struct inode *inode)
35{
36 fsnotify_clear_marks_by_inode(inode);
37}
38EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
39
40void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
41{
42 fsnotify_clear_marks_by_mount(mnt);
43}
44
45/*
46 * Given an inode, first check if we care what happens to our children. Inotify
47 * and dnotify both tell their parents about events. If we care about any event
48 * on a child we run all of our children and set a dentry flag saying that the
49 * parent cares. Thus when an event happens on a child it can quickly tell if
50 * if there is a need to find a parent and send the event to the parent.
51 */
52void __fsnotify_update_child_dentry_flags(struct inode *inode)
53{
54 struct dentry *alias;
55 int watched;
56
57 if (!S_ISDIR(inode->i_mode))
58 return;
59
60 /* determine if the children should tell inode about their events */
61 watched = fsnotify_inode_watches_children(inode);
62
63 spin_lock(&inode->i_lock);
64 /* run all of the dentries associated with this inode. Since this is a
65 * directory, there damn well better only be one item on this list */
66 hlist_for_each_entry(alias, &inode->i_dentry, d_alias) {
67 struct dentry *child;
68
69 /* run all of the children of the original inode and fix their
70 * d_flags to indicate parental interest (their parent is the
71 * original inode) */
72 spin_lock(&alias->d_lock);
73 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
74 if (!child->d_inode)
75 continue;
76
77 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
78 if (watched)
79 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
80 else
81 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
82 spin_unlock(&child->d_lock);
83 }
84 spin_unlock(&alias->d_lock);
85 }
86 spin_unlock(&inode->i_lock);
87}
88
89/* Notify this dentry's parent about a child's events. */
90int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
91{
92 struct dentry *parent;
93 struct inode *p_inode;
94 int ret = 0;
95
96 if (!dentry)
97 dentry = path->dentry;
98
99 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
100 return 0;
101
102 parent = dget_parent(dentry);
103 p_inode = parent->d_inode;
104
105 if (unlikely(!fsnotify_inode_watches_children(p_inode)))
106 __fsnotify_update_child_dentry_flags(p_inode);
107 else if (p_inode->i_fsnotify_mask & mask) {
108 /* we are notifying a parent so come up with the new mask which
109 * specifies these are events which came from a child. */
110 mask |= FS_EVENT_ON_CHILD;
111
112 if (path)
113 ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
114 dentry->d_name.name, 0);
115 else
116 ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
117 dentry->d_name.name, 0);
118 }
119
120 dput(parent);
121
122 return ret;
123}
124EXPORT_SYMBOL_GPL(__fsnotify_parent);
125
126static int send_to_group(struct inode *to_tell,
127 struct fsnotify_mark *inode_mark,
128 struct fsnotify_mark *vfsmount_mark,
129 __u32 mask, void *data,
130 int data_is, u32 cookie,
131 const unsigned char *file_name)
132{
133 struct fsnotify_group *group = NULL;
134 __u32 inode_test_mask = 0;
135 __u32 vfsmount_test_mask = 0;
136
137 if (unlikely(!inode_mark && !vfsmount_mark)) {
138 BUG();
139 return 0;
140 }
141
142 /* clear ignored on inode modification */
143 if (mask & FS_MODIFY) {
144 if (inode_mark &&
145 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
146 inode_mark->ignored_mask = 0;
147 if (vfsmount_mark &&
148 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
149 vfsmount_mark->ignored_mask = 0;
150 }
151
152 /* does the inode mark tell us to do something? */
153 if (inode_mark) {
154 group = inode_mark->group;
155 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
156 inode_test_mask &= inode_mark->mask;
157 inode_test_mask &= ~inode_mark->ignored_mask;
158 }
159
160 /* does the vfsmount_mark tell us to do something? */
161 if (vfsmount_mark) {
162 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
163 group = vfsmount_mark->group;
164 vfsmount_test_mask &= vfsmount_mark->mask;
165 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
166 if (inode_mark)
167 vfsmount_test_mask &= ~inode_mark->ignored_mask;
168 }
169
170 pr_debug("%s: group=%p to_tell=%p mask=%x inode_mark=%p"
171 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
172 " data=%p data_is=%d cookie=%d\n",
173 __func__, group, to_tell, mask, inode_mark,
174 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
175 data_is, cookie);
176
177 if (!inode_test_mask && !vfsmount_test_mask)
178 return 0;
179
180 return group->ops->handle_event(group, to_tell, inode_mark,
181 vfsmount_mark, mask, data, data_is,
182 file_name, cookie);
183}
184
185/*
186 * This is the main call to fsnotify. The VFS calls into hook specific functions
187 * in linux/fsnotify.h. Those functions then in turn call here. Here will call
188 * out to all of the registered fsnotify_group. Those groups can then use the
189 * notification event in whatever means they feel necessary.
190 */
191int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
192 const unsigned char *file_name, u32 cookie)
193{
194 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
195 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
196 struct fsnotify_group *inode_group, *vfsmount_group;
197 struct mount *mnt;
198 int idx, ret = 0;
199 /* global tests shouldn't care about events on child only the specific event */
200 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
201
202 if (data_is == FSNOTIFY_EVENT_PATH)
203 mnt = real_mount(((struct path *)data)->mnt);
204 else
205 mnt = NULL;
206
207 /*
208 * if this is a modify event we may need to clear the ignored masks
209 * otherwise return if neither the inode nor the vfsmount care about
210 * this type of event.
211 */
212 if (!(mask & FS_MODIFY) &&
213 !(test_mask & to_tell->i_fsnotify_mask) &&
214 !(mnt && test_mask & mnt->mnt_fsnotify_mask))
215 return 0;
216
217 idx = srcu_read_lock(&fsnotify_mark_srcu);
218
219 if ((mask & FS_MODIFY) ||
220 (test_mask & to_tell->i_fsnotify_mask))
221 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
222 &fsnotify_mark_srcu);
223
224 if (mnt && ((mask & FS_MODIFY) ||
225 (test_mask & mnt->mnt_fsnotify_mask))) {
226 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
227 &fsnotify_mark_srcu);
228 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
229 &fsnotify_mark_srcu);
230 }
231
232 while (inode_node || vfsmount_node) {
233 inode_group = vfsmount_group = NULL;
234
235 if (inode_node) {
236 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
237 struct fsnotify_mark, i.i_list);
238 inode_group = inode_mark->group;
239 }
240
241 if (vfsmount_node) {
242 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
243 struct fsnotify_mark, m.m_list);
244 vfsmount_group = vfsmount_mark->group;
245 }
246
247 if (inode_group > vfsmount_group) {
248 /* handle inode */
249 ret = send_to_group(to_tell, inode_mark, NULL, mask,
250 data, data_is, cookie, file_name);
251 /* we didn't use the vfsmount_mark */
252 vfsmount_group = NULL;
253 } else if (vfsmount_group > inode_group) {
254 ret = send_to_group(to_tell, NULL, vfsmount_mark, mask,
255 data, data_is, cookie, file_name);
256 inode_group = NULL;
257 } else {
258 ret = send_to_group(to_tell, inode_mark, vfsmount_mark,
259 mask, data, data_is, cookie,
260 file_name);
261 }
262
263 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
264 goto out;
265
266 if (inode_group)
267 inode_node = srcu_dereference(inode_node->next,
268 &fsnotify_mark_srcu);
269 if (vfsmount_group)
270 vfsmount_node = srcu_dereference(vfsmount_node->next,
271 &fsnotify_mark_srcu);
272 }
273 ret = 0;
274out:
275 srcu_read_unlock(&fsnotify_mark_srcu, idx);
276
277 return ret;
278}
279EXPORT_SYMBOL_GPL(fsnotify);
280
281static __init int fsnotify_init(void)
282{
283 int ret;
284
285 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
286
287 ret = init_srcu_struct(&fsnotify_mark_srcu);
288 if (ret)
289 panic("initializing fsnotify_mark_srcu");
290
291 return 0;
292}
293core_initcall(fsnotify_init);
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>
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>
26
27#include <linux/fsnotify_backend.h>
28#include "fsnotify.h"
29
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
39void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
40{
41 fsnotify_clear_marks_by_mount(mnt);
42}
43
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(&inode->i_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 spin_lock(&alias->d_lock);
72 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
73 if (!child->d_inode)
74 continue;
75
76 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
77 if (watched)
78 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
79 else
80 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
81 spin_unlock(&child->d_lock);
82 }
83 spin_unlock(&alias->d_lock);
84 }
85 spin_unlock(&inode->i_lock);
86}
87
88/* Notify this dentry's parent about a child's events. */
89int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
90{
91 struct dentry *parent;
92 struct inode *p_inode;
93 int ret = 0;
94
95 if (!dentry)
96 dentry = path->dentry;
97
98 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
99 return 0;
100
101 parent = dget_parent(dentry);
102 p_inode = parent->d_inode;
103
104 if (unlikely(!fsnotify_inode_watches_children(p_inode)))
105 __fsnotify_update_child_dentry_flags(p_inode);
106 else if (p_inode->i_fsnotify_mask & mask) {
107 /* we are notifying a parent so come up with the new mask which
108 * specifies these are events which came from a child. */
109 mask |= FS_EVENT_ON_CHILD;
110
111 if (path)
112 ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
113 dentry->d_name.name, 0);
114 else
115 ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
116 dentry->d_name.name, 0);
117 }
118
119 dput(parent);
120
121 return ret;
122}
123EXPORT_SYMBOL_GPL(__fsnotify_parent);
124
125static int send_to_group(struct inode *to_tell, struct vfsmount *mnt,
126 struct fsnotify_mark *inode_mark,
127 struct fsnotify_mark *vfsmount_mark,
128 __u32 mask, void *data,
129 int data_is, u32 cookie,
130 const unsigned char *file_name,
131 struct fsnotify_event **event)
132{
133 struct fsnotify_group *group = NULL;
134 __u32 inode_test_mask = 0;
135 __u32 vfsmount_test_mask = 0;
136
137 if (unlikely(!inode_mark && !vfsmount_mark)) {
138 BUG();
139 return 0;
140 }
141
142 /* clear ignored on inode modification */
143 if (mask & FS_MODIFY) {
144 if (inode_mark &&
145 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
146 inode_mark->ignored_mask = 0;
147 if (vfsmount_mark &&
148 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
149 vfsmount_mark->ignored_mask = 0;
150 }
151
152 /* does the inode mark tell us to do something? */
153 if (inode_mark) {
154 group = inode_mark->group;
155 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
156 inode_test_mask &= inode_mark->mask;
157 inode_test_mask &= ~inode_mark->ignored_mask;
158 }
159
160 /* does the vfsmount_mark tell us to do something? */
161 if (vfsmount_mark) {
162 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
163 group = vfsmount_mark->group;
164 vfsmount_test_mask &= vfsmount_mark->mask;
165 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
166 if (inode_mark)
167 vfsmount_test_mask &= ~inode_mark->ignored_mask;
168 }
169
170 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p"
171 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
172 " data=%p data_is=%d cookie=%d event=%p\n",
173 __func__, group, to_tell, mnt, mask, inode_mark,
174 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
175 data_is, cookie, *event);
176
177 if (!inode_test_mask && !vfsmount_test_mask)
178 return 0;
179
180 if (group->ops->should_send_event(group, to_tell, inode_mark,
181 vfsmount_mark, mask, data,
182 data_is) == false)
183 return 0;
184
185 if (!*event) {
186 *event = fsnotify_create_event(to_tell, mask, data,
187 data_is, file_name,
188 cookie, GFP_KERNEL);
189 if (!*event)
190 return -ENOMEM;
191 }
192 return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event);
193}
194
195/*
196 * This is the main call to fsnotify. The VFS calls into hook specific functions
197 * in linux/fsnotify.h. Those functions then in turn call here. Here will call
198 * out to all of the registered fsnotify_group. Those groups can then use the
199 * notification event in whatever means they feel necessary.
200 */
201int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
202 const unsigned char *file_name, u32 cookie)
203{
204 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
205 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
206 struct fsnotify_group *inode_group, *vfsmount_group;
207 struct fsnotify_event *event = NULL;
208 struct vfsmount *mnt;
209 int idx, ret = 0;
210 /* global tests shouldn't care about events on child only the specific event */
211 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
212
213 if (data_is == FSNOTIFY_EVENT_PATH)
214 mnt = ((struct path *)data)->mnt;
215 else
216 mnt = NULL;
217
218 /*
219 * if this is a modify event we may need to clear the ignored masks
220 * otherwise return if neither the inode nor the vfsmount care about
221 * this type of event.
222 */
223 if (!(mask & FS_MODIFY) &&
224 !(test_mask & to_tell->i_fsnotify_mask) &&
225 !(mnt && test_mask & mnt->mnt_fsnotify_mask))
226 return 0;
227
228 idx = srcu_read_lock(&fsnotify_mark_srcu);
229
230 if ((mask & FS_MODIFY) ||
231 (test_mask & to_tell->i_fsnotify_mask))
232 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
233 &fsnotify_mark_srcu);
234
235 if (mnt && ((mask & FS_MODIFY) ||
236 (test_mask & mnt->mnt_fsnotify_mask))) {
237 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
238 &fsnotify_mark_srcu);
239 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
240 &fsnotify_mark_srcu);
241 }
242
243 while (inode_node || vfsmount_node) {
244 inode_group = vfsmount_group = NULL;
245
246 if (inode_node) {
247 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
248 struct fsnotify_mark, i.i_list);
249 inode_group = inode_mark->group;
250 }
251
252 if (vfsmount_node) {
253 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
254 struct fsnotify_mark, m.m_list);
255 vfsmount_group = vfsmount_mark->group;
256 }
257
258 if (inode_group > vfsmount_group) {
259 /* handle inode */
260 ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
261 data_is, cookie, file_name, &event);
262 /* we didn't use the vfsmount_mark */
263 vfsmount_group = NULL;
264 } else if (vfsmount_group > inode_group) {
265 ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
266 data_is, cookie, file_name, &event);
267 inode_group = NULL;
268 } else {
269 ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
270 mask, data, data_is, cookie, file_name,
271 &event);
272 }
273
274 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
275 goto out;
276
277 if (inode_group)
278 inode_node = srcu_dereference(inode_node->next,
279 &fsnotify_mark_srcu);
280 if (vfsmount_group)
281 vfsmount_node = srcu_dereference(vfsmount_node->next,
282 &fsnotify_mark_srcu);
283 }
284 ret = 0;
285out:
286 srcu_read_unlock(&fsnotify_mark_srcu, idx);
287 /*
288 * fsnotify_create_event() took a reference so the event can't be cleaned
289 * up while we are still trying to add it to lists, drop that one.
290 */
291 if (event)
292 fsnotify_put_event(event);
293
294 return ret;
295}
296EXPORT_SYMBOL_GPL(fsnotify);
297
298static __init int fsnotify_init(void)
299{
300 int ret;
301
302 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
303
304 ret = init_srcu_struct(&fsnotify_mark_srcu);
305 if (ret)
306 panic("initializing fsnotify_mark_srcu");
307
308 return 0;
309}
310core_initcall(fsnotify_init);