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0eeca283 RL |
1 | /* |
2 | * fs/inotify.c - inode-based file event notifications | |
3 | * | |
4 | * Authors: | |
5 | * John McCutchan <ttb@tentacle.dhs.org> | |
6 | * Robert Love <rml@novell.com> | |
7 | * | |
8 | * Copyright (C) 2005 John McCutchan | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify it | |
11 | * under the terms of the GNU General Public License as published by the | |
12 | * Free Software Foundation; either version 2, or (at your option) any | |
13 | * later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, but | |
16 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * General Public License for more details. | |
19 | */ | |
20 | ||
21 | #include <linux/module.h> | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/sched.h> | |
24 | #include <linux/spinlock.h> | |
25 | #include <linux/idr.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/fs.h> | |
28 | #include <linux/file.h> | |
29 | #include <linux/mount.h> | |
30 | #include <linux/namei.h> | |
31 | #include <linux/poll.h> | |
0eeca283 RL |
32 | #include <linux/init.h> |
33 | #include <linux/list.h> | |
34 | #include <linux/writeback.h> | |
35 | #include <linux/inotify.h> | |
36 | ||
37 | #include <asm/ioctls.h> | |
38 | ||
39 | static atomic_t inotify_cookie; | |
820249ba | 40 | static atomic_t inotify_watches; |
0eeca283 RL |
41 | |
42 | static kmem_cache_t *watch_cachep; | |
43 | static kmem_cache_t *event_cachep; | |
44 | ||
45 | static struct vfsmount *inotify_mnt; | |
46 | ||
0399cb08 RL |
47 | /* these are configurable via /proc/sys/fs/inotify/ */ |
48 | int inotify_max_user_instances; | |
0eeca283 RL |
49 | int inotify_max_user_watches; |
50 | int inotify_max_queued_events; | |
51 | ||
52 | /* | |
53 | * Lock ordering: | |
54 | * | |
55 | * dentry->d_lock (used to keep d_move() away from dentry->d_parent) | |
56 | * iprune_sem (synchronize shrink_icache_memory()) | |
57 | * inode_lock (protects the super_block->s_inodes list) | |
58 | * inode->inotify_sem (protects inode->inotify_watches and watches->i_list) | |
59 | * inotify_dev->sem (protects inotify_device and watches->d_list) | |
60 | */ | |
61 | ||
62 | /* | |
63 | * Lifetimes of the three main data structures--inotify_device, inode, and | |
64 | * inotify_watch--are managed by reference count. | |
65 | * | |
b680716e RL |
66 | * inotify_device: Lifetime is from inotify_init() until release. Additional |
67 | * references can bump the count via get_inotify_dev() and drop the count via | |
0eeca283 RL |
68 | * put_inotify_dev(). |
69 | * | |
70 | * inotify_watch: Lifetime is from create_watch() to destory_watch(). | |
71 | * Additional references can bump the count via get_inotify_watch() and drop | |
72 | * the count via put_inotify_watch(). | |
73 | * | |
74 | * inode: Pinned so long as the inode is associated with a watch, from | |
75 | * create_watch() to put_inotify_watch(). | |
76 | */ | |
77 | ||
78 | /* | |
b680716e | 79 | * struct inotify_device - represents an inotify instance |
0eeca283 RL |
80 | * |
81 | * This structure is protected by the semaphore 'sem'. | |
82 | */ | |
83 | struct inotify_device { | |
84 | wait_queue_head_t wq; /* wait queue for i/o */ | |
85 | struct idr idr; /* idr mapping wd -> watch */ | |
86 | struct semaphore sem; /* protects this bad boy */ | |
87 | struct list_head events; /* list of queued events */ | |
88 | struct list_head watches; /* list of watches */ | |
89 | atomic_t count; /* reference count */ | |
90 | struct user_struct *user; /* user who opened this dev */ | |
91 | unsigned int queue_size; /* size of the queue (bytes) */ | |
92 | unsigned int event_count; /* number of pending events */ | |
93 | unsigned int max_events; /* maximum number of events */ | |
b9c55d29 | 94 | u32 last_wd; /* the last wd allocated */ |
0eeca283 RL |
95 | }; |
96 | ||
97 | /* | |
98 | * struct inotify_kernel_event - An inotify event, originating from a watch and | |
99 | * queued for user-space. A list of these is attached to each instance of the | |
100 | * device. In read(), this list is walked and all events that can fit in the | |
101 | * buffer are returned. | |
102 | * | |
103 | * Protected by dev->sem of the device in which we are queued. | |
104 | */ | |
105 | struct inotify_kernel_event { | |
106 | struct inotify_event event; /* the user-space event */ | |
107 | struct list_head list; /* entry in inotify_device's list */ | |
108 | char *name; /* filename, if any */ | |
109 | }; | |
110 | ||
111 | /* | |
112 | * struct inotify_watch - represents a watch request on a specific inode | |
113 | * | |
114 | * d_list is protected by dev->sem of the associated watch->dev. | |
115 | * i_list and mask are protected by inode->inotify_sem of the associated inode. | |
116 | * dev, inode, and wd are never written to once the watch is created. | |
117 | */ | |
118 | struct inotify_watch { | |
119 | struct list_head d_list; /* entry in inotify_device's list */ | |
120 | struct list_head i_list; /* entry in inode's list */ | |
121 | atomic_t count; /* reference count */ | |
122 | struct inotify_device *dev; /* associated device */ | |
123 | struct inode *inode; /* associated inode */ | |
124 | s32 wd; /* watch descriptor */ | |
125 | u32 mask; /* event mask for this watch */ | |
126 | }; | |
127 | ||
0399cb08 RL |
128 | #ifdef CONFIG_SYSCTL |
129 | ||
130 | #include <linux/sysctl.h> | |
131 | ||
132 | static int zero; | |
133 | ||
134 | ctl_table inotify_table[] = { | |
135 | { | |
136 | .ctl_name = INOTIFY_MAX_USER_INSTANCES, | |
137 | .procname = "max_user_instances", | |
138 | .data = &inotify_max_user_instances, | |
139 | .maxlen = sizeof(int), | |
140 | .mode = 0644, | |
141 | .proc_handler = &proc_dointvec_minmax, | |
142 | .strategy = &sysctl_intvec, | |
143 | .extra1 = &zero, | |
144 | }, | |
145 | { | |
146 | .ctl_name = INOTIFY_MAX_USER_WATCHES, | |
147 | .procname = "max_user_watches", | |
148 | .data = &inotify_max_user_watches, | |
149 | .maxlen = sizeof(int), | |
150 | .mode = 0644, | |
151 | .proc_handler = &proc_dointvec_minmax, | |
152 | .strategy = &sysctl_intvec, | |
153 | .extra1 = &zero, | |
154 | }, | |
155 | { | |
156 | .ctl_name = INOTIFY_MAX_QUEUED_EVENTS, | |
157 | .procname = "max_queued_events", | |
158 | .data = &inotify_max_queued_events, | |
159 | .maxlen = sizeof(int), | |
160 | .mode = 0644, | |
161 | .proc_handler = &proc_dointvec_minmax, | |
162 | .strategy = &sysctl_intvec, | |
163 | .extra1 = &zero | |
164 | }, | |
165 | { .ctl_name = 0 } | |
166 | }; | |
167 | #endif /* CONFIG_SYSCTL */ | |
168 | ||
0eeca283 RL |
169 | static inline void get_inotify_dev(struct inotify_device *dev) |
170 | { | |
171 | atomic_inc(&dev->count); | |
172 | } | |
173 | ||
174 | static inline void put_inotify_dev(struct inotify_device *dev) | |
175 | { | |
176 | if (atomic_dec_and_test(&dev->count)) { | |
177 | atomic_dec(&dev->user->inotify_devs); | |
178 | free_uid(dev->user); | |
8d3b3591 | 179 | idr_destroy(&dev->idr); |
0eeca283 RL |
180 | kfree(dev); |
181 | } | |
182 | } | |
183 | ||
184 | static inline void get_inotify_watch(struct inotify_watch *watch) | |
185 | { | |
186 | atomic_inc(&watch->count); | |
187 | } | |
188 | ||
189 | /* | |
190 | * put_inotify_watch - decrements the ref count on a given watch. cleans up | |
191 | * the watch and its references if the count reaches zero. | |
192 | */ | |
193 | static inline void put_inotify_watch(struct inotify_watch *watch) | |
194 | { | |
195 | if (atomic_dec_and_test(&watch->count)) { | |
196 | put_inotify_dev(watch->dev); | |
197 | iput(watch->inode); | |
198 | kmem_cache_free(watch_cachep, watch); | |
199 | } | |
200 | } | |
201 | ||
202 | /* | |
203 | * kernel_event - create a new kernel event with the given parameters | |
204 | * | |
205 | * This function can sleep. | |
206 | */ | |
207 | static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie, | |
208 | const char *name) | |
209 | { | |
210 | struct inotify_kernel_event *kevent; | |
211 | ||
212 | kevent = kmem_cache_alloc(event_cachep, GFP_KERNEL); | |
213 | if (unlikely(!kevent)) | |
214 | return NULL; | |
215 | ||
216 | /* we hand this out to user-space, so zero it just in case */ | |
217 | memset(&kevent->event, 0, sizeof(struct inotify_event)); | |
218 | ||
219 | kevent->event.wd = wd; | |
220 | kevent->event.mask = mask; | |
221 | kevent->event.cookie = cookie; | |
222 | ||
223 | INIT_LIST_HEAD(&kevent->list); | |
224 | ||
225 | if (name) { | |
226 | size_t len, rem, event_size = sizeof(struct inotify_event); | |
227 | ||
228 | /* | |
229 | * We need to pad the filename so as to properly align an | |
230 | * array of inotify_event structures. Because the structure is | |
231 | * small and the common case is a small filename, we just round | |
232 | * up to the next multiple of the structure's sizeof. This is | |
233 | * simple and safe for all architectures. | |
234 | */ | |
235 | len = strlen(name) + 1; | |
236 | rem = event_size - len; | |
237 | if (len > event_size) { | |
238 | rem = event_size - (len % event_size); | |
239 | if (len % event_size == 0) | |
240 | rem = 0; | |
241 | } | |
242 | ||
243 | kevent->name = kmalloc(len + rem, GFP_KERNEL); | |
244 | if (unlikely(!kevent->name)) { | |
245 | kmem_cache_free(event_cachep, kevent); | |
246 | return NULL; | |
247 | } | |
248 | memcpy(kevent->name, name, len); | |
249 | if (rem) | |
250 | memset(kevent->name + len, 0, rem); | |
251 | kevent->event.len = len + rem; | |
252 | } else { | |
253 | kevent->event.len = 0; | |
254 | kevent->name = NULL; | |
255 | } | |
256 | ||
257 | return kevent; | |
258 | } | |
259 | ||
260 | /* | |
261 | * inotify_dev_get_event - return the next event in the given dev's queue | |
262 | * | |
263 | * Caller must hold dev->sem. | |
264 | */ | |
265 | static inline struct inotify_kernel_event * | |
266 | inotify_dev_get_event(struct inotify_device *dev) | |
267 | { | |
268 | return list_entry(dev->events.next, struct inotify_kernel_event, list); | |
269 | } | |
270 | ||
271 | /* | |
272 | * inotify_dev_queue_event - add a new event to the given device | |
273 | * | |
274 | * Caller must hold dev->sem. Can sleep (calls kernel_event()). | |
275 | */ | |
276 | static void inotify_dev_queue_event(struct inotify_device *dev, | |
277 | struct inotify_watch *watch, u32 mask, | |
278 | u32 cookie, const char *name) | |
279 | { | |
280 | struct inotify_kernel_event *kevent, *last; | |
281 | ||
282 | /* coalescing: drop this event if it is a dupe of the previous */ | |
283 | last = inotify_dev_get_event(dev); | |
284 | if (last && last->event.mask == mask && last->event.wd == watch->wd && | |
285 | last->event.cookie == cookie) { | |
286 | const char *lastname = last->name; | |
287 | ||
288 | if (!name && !lastname) | |
289 | return; | |
290 | if (name && lastname && !strcmp(lastname, name)) | |
291 | return; | |
292 | } | |
293 | ||
294 | /* the queue overflowed and we already sent the Q_OVERFLOW event */ | |
295 | if (unlikely(dev->event_count > dev->max_events)) | |
296 | return; | |
297 | ||
298 | /* if the queue overflows, we need to notify user space */ | |
299 | if (unlikely(dev->event_count == dev->max_events)) | |
300 | kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL); | |
301 | else | |
302 | kevent = kernel_event(watch->wd, mask, cookie, name); | |
303 | ||
304 | if (unlikely(!kevent)) | |
305 | return; | |
306 | ||
307 | /* queue the event and wake up anyone waiting */ | |
308 | dev->event_count++; | |
309 | dev->queue_size += sizeof(struct inotify_event) + kevent->event.len; | |
310 | list_add_tail(&kevent->list, &dev->events); | |
311 | wake_up_interruptible(&dev->wq); | |
312 | } | |
313 | ||
314 | /* | |
315 | * remove_kevent - cleans up and ultimately frees the given kevent | |
316 | * | |
317 | * Caller must hold dev->sem. | |
318 | */ | |
319 | static void remove_kevent(struct inotify_device *dev, | |
320 | struct inotify_kernel_event *kevent) | |
321 | { | |
322 | list_del(&kevent->list); | |
323 | ||
324 | dev->event_count--; | |
325 | dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len; | |
326 | ||
327 | kfree(kevent->name); | |
328 | kmem_cache_free(event_cachep, kevent); | |
329 | } | |
330 | ||
331 | /* | |
332 | * inotify_dev_event_dequeue - destroy an event on the given device | |
333 | * | |
334 | * Caller must hold dev->sem. | |
335 | */ | |
336 | static void inotify_dev_event_dequeue(struct inotify_device *dev) | |
337 | { | |
338 | if (!list_empty(&dev->events)) { | |
339 | struct inotify_kernel_event *kevent; | |
340 | kevent = inotify_dev_get_event(dev); | |
341 | remove_kevent(dev, kevent); | |
342 | } | |
343 | } | |
344 | ||
345 | /* | |
346 | * inotify_dev_get_wd - returns the next WD for use by the given dev | |
347 | * | |
348 | * Callers must hold dev->sem. This function can sleep. | |
349 | */ | |
350 | static int inotify_dev_get_wd(struct inotify_device *dev, | |
351 | struct inotify_watch *watch) | |
352 | { | |
353 | int ret; | |
354 | ||
355 | do { | |
356 | if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL))) | |
357 | return -ENOSPC; | |
7c657f2f | 358 | ret = idr_get_new_above(&dev->idr, watch, dev->last_wd+1, &watch->wd); |
0eeca283 RL |
359 | } while (ret == -EAGAIN); |
360 | ||
361 | return ret; | |
362 | } | |
363 | ||
364 | /* | |
365 | * find_inode - resolve a user-given path to a specific inode and return a nd | |
366 | */ | |
8140a500 JM |
367 | static int find_inode(const char __user *dirname, struct nameidata *nd, |
368 | unsigned flags) | |
0eeca283 RL |
369 | { |
370 | int error; | |
371 | ||
8140a500 | 372 | error = __user_walk(dirname, flags, nd); |
0eeca283 RL |
373 | if (error) |
374 | return error; | |
375 | /* you can only watch an inode if you have read permissions on it */ | |
e4543edd | 376 | error = vfs_permission(nd, MAY_READ); |
0eeca283 | 377 | if (error) |
b680716e | 378 | path_release(nd); |
0eeca283 RL |
379 | return error; |
380 | } | |
381 | ||
382 | /* | |
383 | * create_watch - creates a watch on the given device. | |
384 | * | |
385 | * Callers must hold dev->sem. Calls inotify_dev_get_wd() so may sleep. | |
386 | * Both 'dev' and 'inode' (by way of nameidata) need to be pinned. | |
387 | */ | |
388 | static struct inotify_watch *create_watch(struct inotify_device *dev, | |
389 | u32 mask, struct inode *inode) | |
390 | { | |
391 | struct inotify_watch *watch; | |
392 | int ret; | |
393 | ||
b680716e RL |
394 | if (atomic_read(&dev->user->inotify_watches) >= |
395 | inotify_max_user_watches) | |
0eeca283 RL |
396 | return ERR_PTR(-ENOSPC); |
397 | ||
398 | watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL); | |
399 | if (unlikely(!watch)) | |
400 | return ERR_PTR(-ENOMEM); | |
401 | ||
402 | ret = inotify_dev_get_wd(dev, watch); | |
403 | if (unlikely(ret)) { | |
404 | kmem_cache_free(watch_cachep, watch); | |
405 | return ERR_PTR(ret); | |
406 | } | |
407 | ||
0bf955ce | 408 | dev->last_wd = watch->wd; |
0eeca283 RL |
409 | watch->mask = mask; |
410 | atomic_set(&watch->count, 0); | |
411 | INIT_LIST_HEAD(&watch->d_list); | |
412 | INIT_LIST_HEAD(&watch->i_list); | |
413 | ||
414 | /* save a reference to device and bump the count to make it official */ | |
415 | get_inotify_dev(dev); | |
416 | watch->dev = dev; | |
417 | ||
418 | /* | |
419 | * Save a reference to the inode and bump the ref count to make it | |
420 | * official. We hold a reference to nameidata, which makes this safe. | |
421 | */ | |
422 | watch->inode = igrab(inode); | |
423 | ||
424 | /* bump our own count, corresponding to our entry in dev->watches */ | |
425 | get_inotify_watch(watch); | |
426 | ||
427 | atomic_inc(&dev->user->inotify_watches); | |
820249ba | 428 | atomic_inc(&inotify_watches); |
0eeca283 RL |
429 | |
430 | return watch; | |
431 | } | |
432 | ||
433 | /* | |
434 | * inotify_find_dev - find the watch associated with the given inode and dev | |
435 | * | |
436 | * Callers must hold inode->inotify_sem. | |
437 | */ | |
438 | static struct inotify_watch *inode_find_dev(struct inode *inode, | |
439 | struct inotify_device *dev) | |
440 | { | |
441 | struct inotify_watch *watch; | |
442 | ||
443 | list_for_each_entry(watch, &inode->inotify_watches, i_list) { | |
444 | if (watch->dev == dev) | |
445 | return watch; | |
446 | } | |
447 | ||
448 | return NULL; | |
449 | } | |
450 | ||
451 | /* | |
452 | * remove_watch_no_event - remove_watch() without the IN_IGNORED event. | |
453 | */ | |
454 | static void remove_watch_no_event(struct inotify_watch *watch, | |
455 | struct inotify_device *dev) | |
456 | { | |
457 | list_del(&watch->i_list); | |
458 | list_del(&watch->d_list); | |
459 | ||
460 | atomic_dec(&dev->user->inotify_watches); | |
820249ba | 461 | atomic_dec(&inotify_watches); |
0eeca283 RL |
462 | idr_remove(&dev->idr, watch->wd); |
463 | put_inotify_watch(watch); | |
464 | } | |
465 | ||
466 | /* | |
467 | * remove_watch - Remove a watch from both the device and the inode. Sends | |
468 | * the IN_IGNORED event to the given device signifying that the inode is no | |
469 | * longer watched. | |
470 | * | |
471 | * Callers must hold both inode->inotify_sem and dev->sem. We drop a | |
472 | * reference to the inode before returning. | |
473 | * | |
474 | * The inode is not iput() so as to remain atomic. If the inode needs to be | |
475 | * iput(), the call returns one. Otherwise, it returns zero. | |
476 | */ | |
477 | static void remove_watch(struct inotify_watch *watch,struct inotify_device *dev) | |
478 | { | |
479 | inotify_dev_queue_event(dev, watch, IN_IGNORED, 0, NULL); | |
480 | remove_watch_no_event(watch, dev); | |
481 | } | |
482 | ||
483 | /* | |
484 | * inotify_inode_watched - returns nonzero if there are watches on this inode | |
485 | * and zero otherwise. We call this lockless, we do not care if we race. | |
486 | */ | |
487 | static inline int inotify_inode_watched(struct inode *inode) | |
488 | { | |
489 | return !list_empty(&inode->inotify_watches); | |
490 | } | |
491 | ||
492 | /* Kernel API */ | |
493 | ||
494 | /** | |
495 | * inotify_inode_queue_event - queue an event to all watches on this inode | |
496 | * @inode: inode event is originating from | |
497 | * @mask: event mask describing this event | |
498 | * @cookie: cookie for synchronization, or zero | |
499 | * @name: filename, if any | |
500 | */ | |
501 | void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie, | |
502 | const char *name) | |
503 | { | |
504 | struct inotify_watch *watch, *next; | |
505 | ||
506 | if (!inotify_inode_watched(inode)) | |
507 | return; | |
508 | ||
509 | down(&inode->inotify_sem); | |
510 | list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) { | |
511 | u32 watch_mask = watch->mask; | |
512 | if (watch_mask & mask) { | |
513 | struct inotify_device *dev = watch->dev; | |
514 | get_inotify_watch(watch); | |
515 | down(&dev->sem); | |
516 | inotify_dev_queue_event(dev, watch, mask, cookie, name); | |
517 | if (watch_mask & IN_ONESHOT) | |
518 | remove_watch_no_event(watch, dev); | |
519 | up(&dev->sem); | |
520 | put_inotify_watch(watch); | |
521 | } | |
522 | } | |
523 | up(&inode->inotify_sem); | |
524 | } | |
525 | EXPORT_SYMBOL_GPL(inotify_inode_queue_event); | |
526 | ||
527 | /** | |
528 | * inotify_dentry_parent_queue_event - queue an event to a dentry's parent | |
529 | * @dentry: the dentry in question, we queue against this dentry's parent | |
530 | * @mask: event mask describing this event | |
531 | * @cookie: cookie for synchronization, or zero | |
532 | * @name: filename, if any | |
533 | */ | |
534 | void inotify_dentry_parent_queue_event(struct dentry *dentry, u32 mask, | |
535 | u32 cookie, const char *name) | |
536 | { | |
537 | struct dentry *parent; | |
538 | struct inode *inode; | |
539 | ||
820249ba JM |
540 | if (!atomic_read (&inotify_watches)) |
541 | return; | |
542 | ||
0eeca283 RL |
543 | spin_lock(&dentry->d_lock); |
544 | parent = dentry->d_parent; | |
545 | inode = parent->d_inode; | |
546 | ||
547 | if (inotify_inode_watched(inode)) { | |
548 | dget(parent); | |
549 | spin_unlock(&dentry->d_lock); | |
550 | inotify_inode_queue_event(inode, mask, cookie, name); | |
551 | dput(parent); | |
552 | } else | |
553 | spin_unlock(&dentry->d_lock); | |
554 | } | |
555 | EXPORT_SYMBOL_GPL(inotify_dentry_parent_queue_event); | |
556 | ||
557 | /** | |
558 | * inotify_get_cookie - return a unique cookie for use in synchronizing events. | |
559 | */ | |
560 | u32 inotify_get_cookie(void) | |
561 | { | |
562 | return atomic_inc_return(&inotify_cookie); | |
563 | } | |
564 | EXPORT_SYMBOL_GPL(inotify_get_cookie); | |
565 | ||
566 | /** | |
567 | * inotify_unmount_inodes - an sb is unmounting. handle any watched inodes. | |
568 | * @list: list of inodes being unmounted (sb->s_inodes) | |
569 | * | |
570 | * Called with inode_lock held, protecting the unmounting super block's list | |
571 | * of inodes, and with iprune_sem held, keeping shrink_icache_memory() at bay. | |
572 | * We temporarily drop inode_lock, however, and CAN block. | |
573 | */ | |
574 | void inotify_unmount_inodes(struct list_head *list) | |
575 | { | |
576 | struct inode *inode, *next_i, *need_iput = NULL; | |
577 | ||
578 | list_for_each_entry_safe(inode, next_i, list, i_sb_list) { | |
579 | struct inotify_watch *watch, *next_w; | |
580 | struct inode *need_iput_tmp; | |
581 | struct list_head *watches; | |
582 | ||
583 | /* | |
584 | * If i_count is zero, the inode cannot have any watches and | |
585 | * doing an __iget/iput with MS_ACTIVE clear would actually | |
586 | * evict all inodes with zero i_count from icache which is | |
587 | * unnecessarily violent and may in fact be illegal to do. | |
588 | */ | |
589 | if (!atomic_read(&inode->i_count)) | |
590 | continue; | |
591 | ||
592 | /* | |
593 | * We cannot __iget() an inode in state I_CLEAR, I_FREEING, or | |
594 | * I_WILL_FREE which is fine because by that point the inode | |
595 | * cannot have any associated watches. | |
596 | */ | |
597 | if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE)) | |
598 | continue; | |
599 | ||
600 | need_iput_tmp = need_iput; | |
601 | need_iput = NULL; | |
602 | /* In case the remove_watch() drops a reference. */ | |
603 | if (inode != need_iput_tmp) | |
604 | __iget(inode); | |
605 | else | |
606 | need_iput_tmp = NULL; | |
607 | /* In case the dropping of a reference would nuke next_i. */ | |
608 | if ((&next_i->i_sb_list != list) && | |
609 | atomic_read(&next_i->i_count) && | |
610 | !(next_i->i_state & (I_CLEAR | I_FREEING | | |
611 | I_WILL_FREE))) { | |
612 | __iget(next_i); | |
613 | need_iput = next_i; | |
614 | } | |
615 | ||
616 | /* | |
617 | * We can safely drop inode_lock here because we hold | |
618 | * references on both inode and next_i. Also no new inodes | |
619 | * will be added since the umount has begun. Finally, | |
620 | * iprune_sem keeps shrink_icache_memory() away. | |
621 | */ | |
622 | spin_unlock(&inode_lock); | |
623 | ||
624 | if (need_iput_tmp) | |
625 | iput(need_iput_tmp); | |
626 | ||
627 | /* for each watch, send IN_UNMOUNT and then remove it */ | |
628 | down(&inode->inotify_sem); | |
629 | watches = &inode->inotify_watches; | |
630 | list_for_each_entry_safe(watch, next_w, watches, i_list) { | |
631 | struct inotify_device *dev = watch->dev; | |
632 | down(&dev->sem); | |
633 | inotify_dev_queue_event(dev, watch, IN_UNMOUNT,0,NULL); | |
634 | remove_watch(watch, dev); | |
635 | up(&dev->sem); | |
636 | } | |
637 | up(&inode->inotify_sem); | |
638 | iput(inode); | |
639 | ||
640 | spin_lock(&inode_lock); | |
641 | } | |
642 | } | |
643 | EXPORT_SYMBOL_GPL(inotify_unmount_inodes); | |
644 | ||
645 | /** | |
646 | * inotify_inode_is_dead - an inode has been deleted, cleanup any watches | |
647 | * @inode: inode that is about to be removed | |
648 | */ | |
649 | void inotify_inode_is_dead(struct inode *inode) | |
650 | { | |
651 | struct inotify_watch *watch, *next; | |
652 | ||
653 | down(&inode->inotify_sem); | |
654 | list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) { | |
655 | struct inotify_device *dev = watch->dev; | |
656 | down(&dev->sem); | |
657 | remove_watch(watch, dev); | |
658 | up(&dev->sem); | |
659 | } | |
660 | up(&inode->inotify_sem); | |
661 | } | |
662 | EXPORT_SYMBOL_GPL(inotify_inode_is_dead); | |
663 | ||
664 | /* Device Interface */ | |
665 | ||
666 | static unsigned int inotify_poll(struct file *file, poll_table *wait) | |
667 | { | |
668 | struct inotify_device *dev = file->private_data; | |
669 | int ret = 0; | |
670 | ||
671 | poll_wait(file, &dev->wq, wait); | |
672 | down(&dev->sem); | |
673 | if (!list_empty(&dev->events)) | |
674 | ret = POLLIN | POLLRDNORM; | |
675 | up(&dev->sem); | |
676 | ||
677 | return ret; | |
678 | } | |
679 | ||
680 | static ssize_t inotify_read(struct file *file, char __user *buf, | |
681 | size_t count, loff_t *pos) | |
682 | { | |
683 | size_t event_size = sizeof (struct inotify_event); | |
684 | struct inotify_device *dev; | |
685 | char __user *start; | |
686 | int ret; | |
687 | DEFINE_WAIT(wait); | |
688 | ||
689 | start = buf; | |
690 | dev = file->private_data; | |
691 | ||
692 | while (1) { | |
693 | int events; | |
694 | ||
695 | prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE); | |
696 | ||
697 | down(&dev->sem); | |
698 | events = !list_empty(&dev->events); | |
699 | up(&dev->sem); | |
700 | if (events) { | |
701 | ret = 0; | |
702 | break; | |
703 | } | |
704 | ||
705 | if (file->f_flags & O_NONBLOCK) { | |
706 | ret = -EAGAIN; | |
707 | break; | |
708 | } | |
709 | ||
710 | if (signal_pending(current)) { | |
711 | ret = -EINTR; | |
712 | break; | |
713 | } | |
714 | ||
715 | schedule(); | |
716 | } | |
717 | ||
718 | finish_wait(&dev->wq, &wait); | |
719 | if (ret) | |
720 | return ret; | |
721 | ||
722 | down(&dev->sem); | |
723 | while (1) { | |
724 | struct inotify_kernel_event *kevent; | |
725 | ||
726 | ret = buf - start; | |
727 | if (list_empty(&dev->events)) | |
728 | break; | |
729 | ||
730 | kevent = inotify_dev_get_event(dev); | |
731 | if (event_size + kevent->event.len > count) | |
732 | break; | |
733 | ||
734 | if (copy_to_user(buf, &kevent->event, event_size)) { | |
735 | ret = -EFAULT; | |
736 | break; | |
737 | } | |
738 | buf += event_size; | |
739 | count -= event_size; | |
740 | ||
741 | if (kevent->name) { | |
742 | if (copy_to_user(buf, kevent->name, kevent->event.len)){ | |
743 | ret = -EFAULT; | |
744 | break; | |
745 | } | |
746 | buf += kevent->event.len; | |
747 | count -= kevent->event.len; | |
748 | } | |
749 | ||
750 | remove_kevent(dev, kevent); | |
751 | } | |
752 | up(&dev->sem); | |
753 | ||
754 | return ret; | |
755 | } | |
756 | ||
757 | static int inotify_release(struct inode *ignored, struct file *file) | |
758 | { | |
759 | struct inotify_device *dev = file->private_data; | |
760 | ||
761 | /* | |
762 | * Destroy all of the watches on this device. Unfortunately, not very | |
763 | * pretty. We cannot do a simple iteration over the list, because we | |
764 | * do not know the inode until we iterate to the watch. But we need to | |
765 | * hold inode->inotify_sem before dev->sem. The following works. | |
766 | */ | |
767 | while (1) { | |
768 | struct inotify_watch *watch; | |
769 | struct list_head *watches; | |
770 | struct inode *inode; | |
771 | ||
772 | down(&dev->sem); | |
773 | watches = &dev->watches; | |
774 | if (list_empty(watches)) { | |
775 | up(&dev->sem); | |
776 | break; | |
777 | } | |
778 | watch = list_entry(watches->next, struct inotify_watch, d_list); | |
779 | get_inotify_watch(watch); | |
780 | up(&dev->sem); | |
781 | ||
782 | inode = watch->inode; | |
783 | down(&inode->inotify_sem); | |
784 | down(&dev->sem); | |
785 | remove_watch_no_event(watch, dev); | |
786 | up(&dev->sem); | |
787 | up(&inode->inotify_sem); | |
788 | put_inotify_watch(watch); | |
789 | } | |
790 | ||
791 | /* destroy all of the events on this device */ | |
792 | down(&dev->sem); | |
793 | while (!list_empty(&dev->events)) | |
794 | inotify_dev_event_dequeue(dev); | |
795 | up(&dev->sem); | |
796 | ||
b680716e | 797 | /* free this device: the put matching the get in inotify_init() */ |
0eeca283 RL |
798 | put_inotify_dev(dev); |
799 | ||
800 | return 0; | |
801 | } | |
802 | ||
803 | /* | |
b680716e | 804 | * inotify_ignore - remove a given wd from this inotify instance. |
0eeca283 RL |
805 | * |
806 | * Can sleep. | |
807 | */ | |
808 | static int inotify_ignore(struct inotify_device *dev, s32 wd) | |
809 | { | |
810 | struct inotify_watch *watch; | |
811 | struct inode *inode; | |
812 | ||
813 | down(&dev->sem); | |
814 | watch = idr_find(&dev->idr, wd); | |
815 | if (unlikely(!watch)) { | |
816 | up(&dev->sem); | |
817 | return -EINVAL; | |
818 | } | |
819 | get_inotify_watch(watch); | |
820 | inode = watch->inode; | |
821 | up(&dev->sem); | |
822 | ||
823 | down(&inode->inotify_sem); | |
824 | down(&dev->sem); | |
825 | ||
826 | /* make sure that we did not race */ | |
827 | watch = idr_find(&dev->idr, wd); | |
828 | if (likely(watch)) | |
829 | remove_watch(watch, dev); | |
830 | ||
831 | up(&dev->sem); | |
832 | up(&inode->inotify_sem); | |
833 | put_inotify_watch(watch); | |
834 | ||
835 | return 0; | |
836 | } | |
837 | ||
838 | static long inotify_ioctl(struct file *file, unsigned int cmd, | |
839 | unsigned long arg) | |
840 | { | |
841 | struct inotify_device *dev; | |
842 | void __user *p; | |
843 | int ret = -ENOTTY; | |
844 | ||
845 | dev = file->private_data; | |
846 | p = (void __user *) arg; | |
847 | ||
848 | switch (cmd) { | |
849 | case FIONREAD: | |
850 | ret = put_user(dev->queue_size, (int __user *) p); | |
851 | break; | |
852 | } | |
853 | ||
854 | return ret; | |
855 | } | |
856 | ||
857 | static struct file_operations inotify_fops = { | |
858 | .poll = inotify_poll, | |
859 | .read = inotify_read, | |
860 | .release = inotify_release, | |
861 | .unlocked_ioctl = inotify_ioctl, | |
862 | .compat_ioctl = inotify_ioctl, | |
863 | }; | |
864 | ||
865 | asmlinkage long sys_inotify_init(void) | |
866 | { | |
867 | struct inotify_device *dev; | |
868 | struct user_struct *user; | |
b680716e RL |
869 | struct file *filp; |
870 | int fd, ret; | |
0eeca283 RL |
871 | |
872 | fd = get_unused_fd(); | |
b680716e RL |
873 | if (fd < 0) |
874 | return fd; | |
0eeca283 RL |
875 | |
876 | filp = get_empty_filp(); | |
877 | if (!filp) { | |
0eeca283 | 878 | ret = -ENFILE; |
5eb22cbc | 879 | goto out_put_fd; |
0eeca283 | 880 | } |
0eeca283 RL |
881 | |
882 | user = get_uid(current->user); | |
b680716e RL |
883 | if (unlikely(atomic_read(&user->inotify_devs) >= |
884 | inotify_max_user_instances)) { | |
0eeca283 | 885 | ret = -EMFILE; |
5eb22cbc | 886 | goto out_free_uid; |
0eeca283 RL |
887 | } |
888 | ||
889 | dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL); | |
890 | if (unlikely(!dev)) { | |
891 | ret = -ENOMEM; | |
5eb22cbc | 892 | goto out_free_uid; |
0eeca283 RL |
893 | } |
894 | ||
b680716e RL |
895 | filp->f_op = &inotify_fops; |
896 | filp->f_vfsmnt = mntget(inotify_mnt); | |
897 | filp->f_dentry = dget(inotify_mnt->mnt_root); | |
898 | filp->f_mapping = filp->f_dentry->d_inode->i_mapping; | |
899 | filp->f_mode = FMODE_READ; | |
900 | filp->f_flags = O_RDONLY; | |
901 | filp->private_data = dev; | |
902 | ||
0eeca283 RL |
903 | idr_init(&dev->idr); |
904 | INIT_LIST_HEAD(&dev->events); | |
905 | INIT_LIST_HEAD(&dev->watches); | |
906 | init_waitqueue_head(&dev->wq); | |
907 | sema_init(&dev->sem, 1); | |
908 | dev->event_count = 0; | |
909 | dev->queue_size = 0; | |
910 | dev->max_events = inotify_max_queued_events; | |
911 | dev->user = user; | |
b9c55d29 | 912 | dev->last_wd = 0; |
0eeca283 RL |
913 | atomic_set(&dev->count, 0); |
914 | ||
915 | get_inotify_dev(dev); | |
916 | atomic_inc(&user->inotify_devs); | |
b680716e | 917 | fd_install(fd, filp); |
0eeca283 | 918 | |
0eeca283 | 919 | return fd; |
5eb22cbc | 920 | out_free_uid: |
0eeca283 | 921 | free_uid(user); |
5eb22cbc RL |
922 | put_filp(filp); |
923 | out_put_fd: | |
924 | put_unused_fd(fd); | |
0eeca283 RL |
925 | return ret; |
926 | } | |
927 | ||
b680716e | 928 | asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask) |
0eeca283 RL |
929 | { |
930 | struct inotify_watch *watch, *old; | |
931 | struct inode *inode; | |
932 | struct inotify_device *dev; | |
933 | struct nameidata nd; | |
934 | struct file *filp; | |
33ea2f52 | 935 | int ret, fput_needed; |
7ea6040b | 936 | int mask_add = 0; |
8140a500 | 937 | unsigned flags = 0; |
0eeca283 | 938 | |
33ea2f52 RL |
939 | filp = fget_light(fd, &fput_needed); |
940 | if (unlikely(!filp)) | |
0eeca283 RL |
941 | return -EBADF; |
942 | ||
783bc29b RL |
943 | /* verify that this is indeed an inotify instance */ |
944 | if (unlikely(filp->f_op != &inotify_fops)) { | |
945 | ret = -EINVAL; | |
946 | goto fput_and_out; | |
947 | } | |
948 | ||
8140a500 JM |
949 | if (!(mask & IN_DONT_FOLLOW)) |
950 | flags |= LOOKUP_FOLLOW; | |
951 | if (mask & IN_ONLYDIR) | |
952 | flags |= LOOKUP_DIRECTORY; | |
953 | ||
954 | ret = find_inode(path, &nd, flags); | |
b680716e | 955 | if (unlikely(ret)) |
0eeca283 RL |
956 | goto fput_and_out; |
957 | ||
b680716e | 958 | /* inode held in place by reference to nd; dev by fget on fd */ |
0eeca283 | 959 | inode = nd.dentry->d_inode; |
b680716e | 960 | dev = filp->private_data; |
0eeca283 RL |
961 | |
962 | down(&inode->inotify_sem); | |
963 | down(&dev->sem); | |
964 | ||
7ea6040b JM |
965 | if (mask & IN_MASK_ADD) |
966 | mask_add = 1; | |
967 | ||
0eeca283 RL |
968 | /* don't let user-space set invalid bits: we don't want flags set */ |
969 | mask &= IN_ALL_EVENTS; | |
b680716e | 970 | if (unlikely(!mask)) { |
0eeca283 RL |
971 | ret = -EINVAL; |
972 | goto out; | |
973 | } | |
974 | ||
975 | /* | |
976 | * Handle the case of re-adding a watch on an (inode,dev) pair that we | |
977 | * are already watching. We just update the mask and return its wd. | |
978 | */ | |
979 | old = inode_find_dev(inode, dev); | |
980 | if (unlikely(old)) { | |
7ea6040b JM |
981 | if (mask_add) |
982 | old->mask |= mask; | |
983 | else | |
984 | old->mask = mask; | |
0eeca283 RL |
985 | ret = old->wd; |
986 | goto out; | |
987 | } | |
988 | ||
989 | watch = create_watch(dev, mask, inode); | |
990 | if (unlikely(IS_ERR(watch))) { | |
991 | ret = PTR_ERR(watch); | |
992 | goto out; | |
993 | } | |
994 | ||
995 | /* Add the watch to the device's and the inode's list */ | |
996 | list_add(&watch->d_list, &dev->watches); | |
997 | list_add(&watch->i_list, &inode->inotify_watches); | |
998 | ret = watch->wd; | |
999 | out: | |
0eeca283 RL |
1000 | up(&dev->sem); |
1001 | up(&inode->inotify_sem); | |
5eb22cbc | 1002 | path_release(&nd); |
0eeca283 | 1003 | fput_and_out: |
33ea2f52 | 1004 | fput_light(filp, fput_needed); |
0eeca283 RL |
1005 | return ret; |
1006 | } | |
1007 | ||
1008 | asmlinkage long sys_inotify_rm_watch(int fd, u32 wd) | |
1009 | { | |
1010 | struct file *filp; | |
1011 | struct inotify_device *dev; | |
33ea2f52 | 1012 | int ret, fput_needed; |
0eeca283 | 1013 | |
33ea2f52 RL |
1014 | filp = fget_light(fd, &fput_needed); |
1015 | if (unlikely(!filp)) | |
0eeca283 | 1016 | return -EBADF; |
783bc29b RL |
1017 | |
1018 | /* verify that this is indeed an inotify instance */ | |
1019 | if (unlikely(filp->f_op != &inotify_fops)) { | |
1020 | ret = -EINVAL; | |
1021 | goto out; | |
1022 | } | |
1023 | ||
0eeca283 | 1024 | dev = filp->private_data; |
9a556e89 | 1025 | ret = inotify_ignore(dev, wd); |
9a556e89 | 1026 | |
783bc29b RL |
1027 | out: |
1028 | fput_light(filp, fput_needed); | |
0eeca283 RL |
1029 | return ret; |
1030 | } | |
1031 | ||
1032 | static struct super_block * | |
1033 | inotify_get_sb(struct file_system_type *fs_type, int flags, | |
1034 | const char *dev_name, void *data) | |
1035 | { | |
1036 | return get_sb_pseudo(fs_type, "inotify", NULL, 0xBAD1DEA); | |
1037 | } | |
1038 | ||
1039 | static struct file_system_type inotify_fs_type = { | |
1040 | .name = "inotifyfs", | |
1041 | .get_sb = inotify_get_sb, | |
1042 | .kill_sb = kill_anon_super, | |
1043 | }; | |
1044 | ||
1045 | /* | |
b680716e | 1046 | * inotify_setup - Our initialization function. Note that we cannnot return |
0eeca283 RL |
1047 | * error because we have compiled-in VFS hooks. So an (unlikely) failure here |
1048 | * must result in panic(). | |
1049 | */ | |
b680716e | 1050 | static int __init inotify_setup(void) |
0eeca283 | 1051 | { |
e5ca844a RL |
1052 | int ret; |
1053 | ||
1054 | ret = register_filesystem(&inotify_fs_type); | |
1055 | if (unlikely(ret)) | |
1056 | panic("inotify: register_filesystem returned %d!\n", ret); | |
1057 | ||
0eeca283 | 1058 | inotify_mnt = kern_mount(&inotify_fs_type); |
89373de7 | 1059 | if (IS_ERR(inotify_mnt)) |
e5ca844a | 1060 | panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt)); |
0eeca283 | 1061 | |
1b2ccf0c RL |
1062 | inotify_max_queued_events = 16384; |
1063 | inotify_max_user_instances = 128; | |
0eeca283 RL |
1064 | inotify_max_user_watches = 8192; |
1065 | ||
1066 | atomic_set(&inotify_cookie, 0); | |
820249ba | 1067 | atomic_set(&inotify_watches, 0); |
0eeca283 RL |
1068 | |
1069 | watch_cachep = kmem_cache_create("inotify_watch_cache", | |
1070 | sizeof(struct inotify_watch), | |
1071 | 0, SLAB_PANIC, NULL, NULL); | |
1072 | event_cachep = kmem_cache_create("inotify_event_cache", | |
1073 | sizeof(struct inotify_kernel_event), | |
1074 | 0, SLAB_PANIC, NULL, NULL); | |
1075 | ||
0eeca283 RL |
1076 | return 0; |
1077 | } | |
1078 | ||
b680716e | 1079 | module_init(inotify_setup); |