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19#include <linux/fs.h>
20#include <linux/module.h>
21#include <linux/sched.h>
22#include <linux/dnotify.h>
23#include <linux/init.h>
24#include <linux/spinlock.h>
25#include <linux/slab.h>
26#include <linux/fdtable.h>
27#include <linux/fsnotify_backend.h>
28
29int dir_notify_enable __read_mostly = 1;
30
31static struct kmem_cache *dnotify_struct_cache __read_mostly;
32static struct kmem_cache *dnotify_mark_cache __read_mostly;
33static struct fsnotify_group *dnotify_group __read_mostly;
34static DEFINE_MUTEX(dnotify_mark_mutex);
35
36
37
38
39
40
41struct dnotify_mark {
42 struct fsnotify_mark fsn_mark;
43 struct dnotify_struct *dn;
44};
45
46
47
48
49
50
51
52
53
54static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark)
55{
56 __u32 new_mask, old_mask;
57 struct dnotify_struct *dn;
58 struct dnotify_mark *dn_mark = container_of(fsn_mark,
59 struct dnotify_mark,
60 fsn_mark);
61
62 assert_spin_locked(&fsn_mark->lock);
63
64 old_mask = fsn_mark->mask;
65 new_mask = 0;
66 for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next)
67 new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT);
68 fsnotify_set_mark_mask_locked(fsn_mark, new_mask);
69
70 if (old_mask == new_mask)
71 return;
72
73 if (fsn_mark->i.inode)
74 fsnotify_recalc_inode_mask(fsn_mark->i.inode);
75}
76
77
78
79
80
81
82
83
84
85static int dnotify_handle_event(struct fsnotify_group *group,
86 struct fsnotify_mark *inode_mark,
87 struct fsnotify_mark *vfsmount_mark,
88 struct fsnotify_event *event)
89{
90 struct dnotify_mark *dn_mark;
91 struct inode *to_tell;
92 struct dnotify_struct *dn;
93 struct dnotify_struct **prev;
94 struct fown_struct *fown;
95 __u32 test_mask = event->mask & ~FS_EVENT_ON_CHILD;
96
97 BUG_ON(vfsmount_mark);
98
99 to_tell = event->to_tell;
100
101 dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark);
102
103 spin_lock(&inode_mark->lock);
104 prev = &dn_mark->dn;
105 while ((dn = *prev) != NULL) {
106 if ((dn->dn_mask & test_mask) == 0) {
107 prev = &dn->dn_next;
108 continue;
109 }
110 fown = &dn->dn_filp->f_owner;
111 send_sigio(fown, dn->dn_fd, POLL_MSG);
112 if (dn->dn_mask & FS_DN_MULTISHOT)
113 prev = &dn->dn_next;
114 else {
115 *prev = dn->dn_next;
116 kmem_cache_free(dnotify_struct_cache, dn);
117 dnotify_recalc_inode_mask(inode_mark);
118 }
119 }
120
121 spin_unlock(&inode_mark->lock);
122
123 return 0;
124}
125
126
127
128
129
130static bool dnotify_should_send_event(struct fsnotify_group *group,
131 struct inode *inode,
132 struct fsnotify_mark *inode_mark,
133 struct fsnotify_mark *vfsmount_mark,
134 __u32 mask, void *data, int data_type)
135{
136
137 if (!S_ISDIR(inode->i_mode))
138 return false;
139
140 return true;
141}
142
143static void dnotify_free_mark(struct fsnotify_mark *fsn_mark)
144{
145 struct dnotify_mark *dn_mark = container_of(fsn_mark,
146 struct dnotify_mark,
147 fsn_mark);
148
149 BUG_ON(dn_mark->dn);
150
151 kmem_cache_free(dnotify_mark_cache, dn_mark);
152}
153
154static struct fsnotify_ops dnotify_fsnotify_ops = {
155 .handle_event = dnotify_handle_event,
156 .should_send_event = dnotify_should_send_event,
157 .free_group_priv = NULL,
158 .freeing_mark = NULL,
159 .free_event_priv = NULL,
160};
161
162
163
164
165
166
167
168
169void dnotify_flush(struct file *filp, fl_owner_t id)
170{
171 struct fsnotify_mark *fsn_mark;
172 struct dnotify_mark *dn_mark;
173 struct dnotify_struct *dn;
174 struct dnotify_struct **prev;
175 struct inode *inode;
176
177 inode = file_inode(filp);
178 if (!S_ISDIR(inode->i_mode))
179 return;
180
181 fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode);
182 if (!fsn_mark)
183 return;
184 dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
185
186 mutex_lock(&dnotify_mark_mutex);
187
188 spin_lock(&fsn_mark->lock);
189 prev = &dn_mark->dn;
190 while ((dn = *prev) != NULL) {
191 if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
192 *prev = dn->dn_next;
193 kmem_cache_free(dnotify_struct_cache, dn);
194 dnotify_recalc_inode_mask(fsn_mark);
195 break;
196 }
197 prev = &dn->dn_next;
198 }
199
200 spin_unlock(&fsn_mark->lock);
201
202
203 if (dn_mark->dn == NULL)
204 fsnotify_destroy_mark(fsn_mark, dnotify_group);
205
206 mutex_unlock(&dnotify_mark_mutex);
207
208 fsnotify_put_mark(fsn_mark);
209}
210
211
212static __u32 convert_arg(unsigned long arg)
213{
214 __u32 new_mask = FS_EVENT_ON_CHILD;
215
216 if (arg & DN_MULTISHOT)
217 new_mask |= FS_DN_MULTISHOT;
218 if (arg & DN_DELETE)
219 new_mask |= (FS_DELETE | FS_MOVED_FROM);
220 if (arg & DN_MODIFY)
221 new_mask |= FS_MODIFY;
222 if (arg & DN_ACCESS)
223 new_mask |= FS_ACCESS;
224 if (arg & DN_ATTRIB)
225 new_mask |= FS_ATTRIB;
226 if (arg & DN_RENAME)
227 new_mask |= FS_DN_RENAME;
228 if (arg & DN_CREATE)
229 new_mask |= (FS_CREATE | FS_MOVED_TO);
230
231 return new_mask;
232}
233
234
235
236
237
238
239
240static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark *dn_mark,
241 fl_owner_t id, int fd, struct file *filp, __u32 mask)
242{
243 struct dnotify_struct *odn;
244
245 odn = dn_mark->dn;
246 while (odn != NULL) {
247
248 if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
249 odn->dn_fd = fd;
250 odn->dn_mask |= mask;
251 return -EEXIST;
252 }
253 odn = odn->dn_next;
254 }
255
256 dn->dn_mask = mask;
257 dn->dn_fd = fd;
258 dn->dn_filp = filp;
259 dn->dn_owner = id;
260 dn->dn_next = dn_mark->dn;
261 dn_mark->dn = dn;
262
263 return 0;
264}
265
266
267
268
269
270
271int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
272{
273 struct dnotify_mark *new_dn_mark, *dn_mark;
274 struct fsnotify_mark *new_fsn_mark, *fsn_mark;
275 struct dnotify_struct *dn;
276 struct inode *inode;
277 fl_owner_t id = current->files;
278 struct file *f;
279 int destroy = 0, error = 0;
280 __u32 mask;
281
282
283 new_fsn_mark = NULL;
284 dn = NULL;
285
286 if (!dir_notify_enable) {
287 error = -EINVAL;
288 goto out_err;
289 }
290
291
292 if ((arg & ~DN_MULTISHOT) == 0) {
293 dnotify_flush(filp, id);
294 error = 0;
295 goto out_err;
296 }
297
298
299 inode = file_inode(filp);
300 if (!S_ISDIR(inode->i_mode)) {
301 error = -ENOTDIR;
302 goto out_err;
303 }
304
305
306 dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL);
307 if (!dn) {
308 error = -ENOMEM;
309 goto out_err;
310 }
311
312
313 new_dn_mark = kmem_cache_alloc(dnotify_mark_cache, GFP_KERNEL);
314 if (!new_dn_mark) {
315 error = -ENOMEM;
316 goto out_err;
317 }
318
319
320 mask = convert_arg(arg);
321
322
323 new_fsn_mark = &new_dn_mark->fsn_mark;
324 fsnotify_init_mark(new_fsn_mark, dnotify_free_mark);
325 new_fsn_mark->mask = mask;
326 new_dn_mark->dn = NULL;
327
328
329 mutex_lock(&dnotify_mark_mutex);
330
331
332 fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode);
333 if (fsn_mark) {
334 dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
335 spin_lock(&fsn_mark->lock);
336 } else {
337 fsnotify_add_mark(new_fsn_mark, dnotify_group, inode, NULL, 0);
338 spin_lock(&new_fsn_mark->lock);
339 fsn_mark = new_fsn_mark;
340 dn_mark = new_dn_mark;
341
342 new_fsn_mark = NULL;
343 }
344
345 rcu_read_lock();
346 f = fcheck(fd);
347 rcu_read_unlock();
348
349
350
351
352
353
354 if (f != filp) {
355
356
357
358
359
360
361 if (dn_mark == new_dn_mark)
362 destroy = 1;
363 goto out;
364 }
365
366 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
367 if (error) {
368
369 if (dn_mark == new_dn_mark)
370 destroy = 1;
371 goto out;
372 }
373
374 error = attach_dn(dn, dn_mark, id, fd, filp, mask);
375
376 if (!error)
377 dn = NULL;
378
379
380 else if (error == -EEXIST)
381 error = 0;
382
383 dnotify_recalc_inode_mask(fsn_mark);
384out:
385 spin_unlock(&fsn_mark->lock);
386
387 if (destroy)
388 fsnotify_destroy_mark(fsn_mark, dnotify_group);
389
390 mutex_unlock(&dnotify_mark_mutex);
391 fsnotify_put_mark(fsn_mark);
392out_err:
393 if (new_fsn_mark)
394 fsnotify_put_mark(new_fsn_mark);
395 if (dn)
396 kmem_cache_free(dnotify_struct_cache, dn);
397 return error;
398}
399
400static int __init dnotify_init(void)
401{
402 dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
403 dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC);
404
405 dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops);
406 if (IS_ERR(dnotify_group))
407 panic("unable to allocate fsnotify group for dnotify\n");
408 return 0;
409}
410
411module_init(dnotify_init)
412