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-rw-r--r--fs/notify/inotify/Kconfig27
-rw-r--r--fs/notify/inotify/Makefile2
-rw-r--r--fs/notify/inotify/inotify.c913
-rw-r--r--fs/notify/inotify/inotify_user.c792
4 files changed, 1734 insertions, 0 deletions
diff --git a/fs/notify/inotify/Kconfig b/fs/notify/inotify/Kconfig
new file mode 100644
index 000000000000..446792841023
--- /dev/null
+++ b/fs/notify/inotify/Kconfig
@@ -0,0 +1,27 @@
1config INOTIFY
2 bool "Inotify file change notification support"
3 default y
4 ---help---
5 Say Y here to enable inotify support. Inotify is a file change
6 notification system and a replacement for dnotify. Inotify fixes
7 numerous shortcomings in dnotify and introduces several new features
8 including multiple file events, one-shot support, and unmount
9 notification.
10
11 For more information, see <file:Documentation/filesystems/inotify.txt>
12
13 If unsure, say Y.
14
15config INOTIFY_USER
16 bool "Inotify support for userspace"
17 depends on INOTIFY
18 default y
19 ---help---
20 Say Y here to enable inotify support for userspace, including the
21 associated system calls. Inotify allows monitoring of both files and
22 directories via a single open fd. Events are read from the file
23 descriptor, which is also select()- and poll()-able.
24
25 For more information, see <file:Documentation/filesystems/inotify.txt>
26
27 If unsure, say Y.
diff --git a/fs/notify/inotify/Makefile b/fs/notify/inotify/Makefile
new file mode 100644
index 000000000000..e290f3bb9d8d
--- /dev/null
+++ b/fs/notify/inotify/Makefile
@@ -0,0 +1,2 @@
1obj-$(CONFIG_INOTIFY) += inotify.o
2obj-$(CONFIG_INOTIFY_USER) += inotify_user.o
diff --git a/fs/notify/inotify/inotify.c b/fs/notify/inotify/inotify.c
new file mode 100644
index 000000000000..dae3f28f30d4
--- /dev/null
+++ b/fs/notify/inotify/inotify.c
@@ -0,0 +1,913 @@
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 * Kernel API added by: Amy Griffis <amy.griffis@hp.com>
9 *
10 * Copyright (C) 2005 John McCutchan
11 * Copyright 2006 Hewlett-Packard Development Company, L.P.
12 *
13 * This program is free software; you can redistribute it and/or modify it
14 * under the terms of the GNU General Public License as published by the
15 * Free Software Foundation; either version 2, or (at your option) any
16 * later version.
17 *
18 * This program is distributed in the hope that it will be useful, but
19 * WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 * General Public License for more details.
22 */
23
24#include <linux/module.h>
25#include <linux/kernel.h>
26#include <linux/spinlock.h>
27#include <linux/idr.h>
28#include <linux/slab.h>
29#include <linux/fs.h>
30#include <linux/sched.h>
31#include <linux/init.h>
32#include <linux/list.h>
33#include <linux/writeback.h>
34#include <linux/inotify.h>
35
36static atomic_t inotify_cookie;
37
38/*
39 * Lock ordering:
40 *
41 * dentry->d_lock (used to keep d_move() away from dentry->d_parent)
42 * iprune_mutex (synchronize shrink_icache_memory())
43 * inode_lock (protects the super_block->s_inodes list)
44 * inode->inotify_mutex (protects inode->inotify_watches and watches->i_list)
45 * inotify_handle->mutex (protects inotify_handle and watches->h_list)
46 *
47 * The inode->inotify_mutex and inotify_handle->mutex and held during execution
48 * of a caller's event handler. Thus, the caller must not hold any locks
49 * taken in their event handler while calling any of the published inotify
50 * interfaces.
51 */
52
53/*
54 * Lifetimes of the three main data structures--inotify_handle, inode, and
55 * inotify_watch--are managed by reference count.
56 *
57 * inotify_handle: Lifetime is from inotify_init() to inotify_destroy().
58 * Additional references can bump the count via get_inotify_handle() and drop
59 * the count via put_inotify_handle().
60 *
61 * inotify_watch: for inotify's purposes, lifetime is from inotify_add_watch()
62 * to remove_watch_no_event(). Additional references can bump the count via
63 * get_inotify_watch() and drop the count via put_inotify_watch(). The caller
64 * is reponsible for the final put after receiving IN_IGNORED, or when using
65 * IN_ONESHOT after receiving the first event. Inotify does the final put if
66 * inotify_destroy() is called.
67 *
68 * inode: Pinned so long as the inode is associated with a watch, from
69 * inotify_add_watch() to the final put_inotify_watch().
70 */
71
72/*
73 * struct inotify_handle - represents an inotify instance
74 *
75 * This structure is protected by the mutex 'mutex'.
76 */
77struct inotify_handle {
78 struct idr idr; /* idr mapping wd -> watch */
79 struct mutex mutex; /* protects this bad boy */
80 struct list_head watches; /* list of watches */
81 atomic_t count; /* reference count */
82 u32 last_wd; /* the last wd allocated */
83 const struct inotify_operations *in_ops; /* inotify caller operations */
84};
85
86static inline void get_inotify_handle(struct inotify_handle *ih)
87{
88 atomic_inc(&ih->count);
89}
90
91static inline void put_inotify_handle(struct inotify_handle *ih)
92{
93 if (atomic_dec_and_test(&ih->count)) {
94 idr_destroy(&ih->idr);
95 kfree(ih);
96 }
97}
98
99/**
100 * get_inotify_watch - grab a reference to an inotify_watch
101 * @watch: watch to grab
102 */
103void get_inotify_watch(struct inotify_watch *watch)
104{
105 atomic_inc(&watch->count);
106}
107EXPORT_SYMBOL_GPL(get_inotify_watch);
108
109int pin_inotify_watch(struct inotify_watch *watch)
110{
111 struct super_block *sb = watch->inode->i_sb;
112 spin_lock(&sb_lock);
113 if (sb->s_count >= S_BIAS) {
114 atomic_inc(&sb->s_active);
115 spin_unlock(&sb_lock);
116 atomic_inc(&watch->count);
117 return 1;
118 }
119 spin_unlock(&sb_lock);
120 return 0;
121}
122
123/**
124 * put_inotify_watch - decrements the ref count on a given watch. cleans up
125 * watch references if the count reaches zero. inotify_watch is freed by
126 * inotify callers via the destroy_watch() op.
127 * @watch: watch to release
128 */
129void put_inotify_watch(struct inotify_watch *watch)
130{
131 if (atomic_dec_and_test(&watch->count)) {
132 struct inotify_handle *ih = watch->ih;
133
134 iput(watch->inode);
135 ih->in_ops->destroy_watch(watch);
136 put_inotify_handle(ih);
137 }
138}
139EXPORT_SYMBOL_GPL(put_inotify_watch);
140
141void unpin_inotify_watch(struct inotify_watch *watch)
142{
143 struct super_block *sb = watch->inode->i_sb;
144 put_inotify_watch(watch);
145 deactivate_super(sb);
146}
147
148/*
149 * inotify_handle_get_wd - returns the next WD for use by the given handle
150 *
151 * Callers must hold ih->mutex. This function can sleep.
152 */
153static int inotify_handle_get_wd(struct inotify_handle *ih,
154 struct inotify_watch *watch)
155{
156 int ret;
157
158 do {
159 if (unlikely(!idr_pre_get(&ih->idr, GFP_KERNEL)))
160 return -ENOSPC;
161 ret = idr_get_new_above(&ih->idr, watch, ih->last_wd+1, &watch->wd);
162 } while (ret == -EAGAIN);
163
164 if (likely(!ret))
165 ih->last_wd = watch->wd;
166
167 return ret;
168}
169
170/*
171 * inotify_inode_watched - returns nonzero if there are watches on this inode
172 * and zero otherwise. We call this lockless, we do not care if we race.
173 */
174static inline int inotify_inode_watched(struct inode *inode)
175{
176 return !list_empty(&inode->inotify_watches);
177}
178
179/*
180 * Get child dentry flag into synch with parent inode.
181 * Flag should always be clear for negative dentrys.
182 */
183static void set_dentry_child_flags(struct inode *inode, int watched)
184{
185 struct dentry *alias;
186
187 spin_lock(&dcache_lock);
188 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
189 struct dentry *child;
190
191 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
192 if (!child->d_inode)
193 continue;
194
195 spin_lock(&child->d_lock);
196 if (watched)
197 child->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
198 else
199 child->d_flags &=~DCACHE_INOTIFY_PARENT_WATCHED;
200 spin_unlock(&child->d_lock);
201 }
202 }
203 spin_unlock(&dcache_lock);
204}
205
206/*
207 * inotify_find_handle - find the watch associated with the given inode and
208 * handle
209 *
210 * Callers must hold inode->inotify_mutex.
211 */
212static struct inotify_watch *inode_find_handle(struct inode *inode,
213 struct inotify_handle *ih)
214{
215 struct inotify_watch *watch;
216
217 list_for_each_entry(watch, &inode->inotify_watches, i_list) {
218 if (watch->ih == ih)
219 return watch;
220 }
221
222 return NULL;
223}
224
225/*
226 * remove_watch_no_event - remove watch without the IN_IGNORED event.
227 *
228 * Callers must hold both inode->inotify_mutex and ih->mutex.
229 */
230static void remove_watch_no_event(struct inotify_watch *watch,
231 struct inotify_handle *ih)
232{
233 list_del(&watch->i_list);
234 list_del(&watch->h_list);
235
236 if (!inotify_inode_watched(watch->inode))
237 set_dentry_child_flags(watch->inode, 0);
238
239 idr_remove(&ih->idr, watch->wd);
240}
241
242/**
243 * inotify_remove_watch_locked - Remove a watch from both the handle and the
244 * inode. Sends the IN_IGNORED event signifying that the inode is no longer
245 * watched. May be invoked from a caller's event handler.
246 * @ih: inotify handle associated with watch
247 * @watch: watch to remove
248 *
249 * Callers must hold both inode->inotify_mutex and ih->mutex.
250 */
251void inotify_remove_watch_locked(struct inotify_handle *ih,
252 struct inotify_watch *watch)
253{
254 remove_watch_no_event(watch, ih);
255 ih->in_ops->handle_event(watch, watch->wd, IN_IGNORED, 0, NULL, NULL);
256}
257EXPORT_SYMBOL_GPL(inotify_remove_watch_locked);
258
259/* Kernel API for producing events */
260
261/*
262 * inotify_d_instantiate - instantiate dcache entry for inode
263 */
264void inotify_d_instantiate(struct dentry *entry, struct inode *inode)
265{
266 struct dentry *parent;
267
268 if (!inode)
269 return;
270
271 spin_lock(&entry->d_lock);
272 parent = entry->d_parent;
273 if (parent->d_inode && inotify_inode_watched(parent->d_inode))
274 entry->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
275 spin_unlock(&entry->d_lock);
276}
277
278/*
279 * inotify_d_move - dcache entry has been moved
280 */
281void inotify_d_move(struct dentry *entry)
282{
283 struct dentry *parent;
284
285 parent = entry->d_parent;
286 if (inotify_inode_watched(parent->d_inode))
287 entry->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
288 else
289 entry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED;
290}
291
292/**
293 * inotify_inode_queue_event - queue an event to all watches on this inode
294 * @inode: inode event is originating from
295 * @mask: event mask describing this event
296 * @cookie: cookie for synchronization, or zero
297 * @name: filename, if any
298 * @n_inode: inode associated with name
299 */
300void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie,
301 const char *name, struct inode *n_inode)
302{
303 struct inotify_watch *watch, *next;
304
305 if (!inotify_inode_watched(inode))
306 return;
307
308 mutex_lock(&inode->inotify_mutex);
309 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
310 u32 watch_mask = watch->mask;
311 if (watch_mask & mask) {
312 struct inotify_handle *ih= watch->ih;
313 mutex_lock(&ih->mutex);
314 if (watch_mask & IN_ONESHOT)
315 remove_watch_no_event(watch, ih);
316 ih->in_ops->handle_event(watch, watch->wd, mask, cookie,
317 name, n_inode);
318 mutex_unlock(&ih->mutex);
319 }
320 }
321 mutex_unlock(&inode->inotify_mutex);
322}
323EXPORT_SYMBOL_GPL(inotify_inode_queue_event);
324
325/**
326 * inotify_dentry_parent_queue_event - queue an event to a dentry's parent
327 * @dentry: the dentry in question, we queue against this dentry's parent
328 * @mask: event mask describing this event
329 * @cookie: cookie for synchronization, or zero
330 * @name: filename, if any
331 */
332void inotify_dentry_parent_queue_event(struct dentry *dentry, u32 mask,
333 u32 cookie, const char *name)
334{
335 struct dentry *parent;
336 struct inode *inode;
337
338 if (!(dentry->d_flags & DCACHE_INOTIFY_PARENT_WATCHED))
339 return;
340
341 spin_lock(&dentry->d_lock);
342 parent = dentry->d_parent;
343 inode = parent->d_inode;
344
345 if (inotify_inode_watched(inode)) {
346 dget(parent);
347 spin_unlock(&dentry->d_lock);
348 inotify_inode_queue_event(inode, mask, cookie, name,
349 dentry->d_inode);
350 dput(parent);
351 } else
352 spin_unlock(&dentry->d_lock);
353}
354EXPORT_SYMBOL_GPL(inotify_dentry_parent_queue_event);
355
356/**
357 * inotify_get_cookie - return a unique cookie for use in synchronizing events.
358 */
359u32 inotify_get_cookie(void)
360{
361 return atomic_inc_return(&inotify_cookie);
362}
363EXPORT_SYMBOL_GPL(inotify_get_cookie);
364
365/**
366 * inotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
367 * @list: list of inodes being unmounted (sb->s_inodes)
368 *
369 * Called with inode_lock held, protecting the unmounting super block's list
370 * of inodes, and with iprune_mutex held, keeping shrink_icache_memory() at bay.
371 * We temporarily drop inode_lock, however, and CAN block.
372 */
373void inotify_unmount_inodes(struct list_head *list)
374{
375 struct inode *inode, *next_i, *need_iput = NULL;
376
377 list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
378 struct inotify_watch *watch, *next_w;
379 struct inode *need_iput_tmp;
380 struct list_head *watches;
381
382 /*
383 * If i_count is zero, the inode cannot have any watches and
384 * doing an __iget/iput with MS_ACTIVE clear would actually
385 * evict all inodes with zero i_count from icache which is
386 * unnecessarily violent and may in fact be illegal to do.
387 */
388 if (!atomic_read(&inode->i_count))
389 continue;
390
391 /*
392 * We cannot __iget() an inode in state I_CLEAR, I_FREEING, or
393 * I_WILL_FREE which is fine because by that point the inode
394 * cannot have any associated watches.
395 */
396 if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))
397 continue;
398
399 need_iput_tmp = need_iput;
400 need_iput = NULL;
401 /* In case inotify_remove_watch_locked() drops a reference. */
402 if (inode != need_iput_tmp)
403 __iget(inode);
404 else
405 need_iput_tmp = NULL;
406 /* In case the dropping of a reference would nuke next_i. */
407 if ((&next_i->i_sb_list != list) &&
408 atomic_read(&next_i->i_count) &&
409 !(next_i->i_state & (I_CLEAR | I_FREEING |
410 I_WILL_FREE))) {
411 __iget(next_i);
412 need_iput = next_i;
413 }
414
415 /*
416 * We can safely drop inode_lock here because we hold
417 * references on both inode and next_i. Also no new inodes
418 * will be added since the umount has begun. Finally,
419 * iprune_mutex keeps shrink_icache_memory() away.
420 */
421 spin_unlock(&inode_lock);
422
423 if (need_iput_tmp)
424 iput(need_iput_tmp);
425
426 /* for each watch, send IN_UNMOUNT and then remove it */
427 mutex_lock(&inode->inotify_mutex);
428 watches = &inode->inotify_watches;
429 list_for_each_entry_safe(watch, next_w, watches, i_list) {
430 struct inotify_handle *ih= watch->ih;
431 get_inotify_watch(watch);
432 mutex_lock(&ih->mutex);
433 ih->in_ops->handle_event(watch, watch->wd, IN_UNMOUNT, 0,
434 NULL, NULL);
435 inotify_remove_watch_locked(ih, watch);
436 mutex_unlock(&ih->mutex);
437 put_inotify_watch(watch);
438 }
439 mutex_unlock(&inode->inotify_mutex);
440 iput(inode);
441
442 spin_lock(&inode_lock);
443 }
444}
445EXPORT_SYMBOL_GPL(inotify_unmount_inodes);
446
447/**
448 * inotify_inode_is_dead - an inode has been deleted, cleanup any watches
449 * @inode: inode that is about to be removed
450 */
451void inotify_inode_is_dead(struct inode *inode)
452{
453 struct inotify_watch *watch, *next;
454
455 mutex_lock(&inode->inotify_mutex);
456 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
457 struct inotify_handle *ih = watch->ih;
458 mutex_lock(&ih->mutex);
459 inotify_remove_watch_locked(ih, watch);
460 mutex_unlock(&ih->mutex);
461 }
462 mutex_unlock(&inode->inotify_mutex);
463}
464EXPORT_SYMBOL_GPL(inotify_inode_is_dead);
465
466/* Kernel Consumer API */
467
468/**
469 * inotify_init - allocate and initialize an inotify instance
470 * @ops: caller's inotify operations
471 */
472struct inotify_handle *inotify_init(const struct inotify_operations *ops)
473{
474 struct inotify_handle *ih;
475
476 ih = kmalloc(sizeof(struct inotify_handle), GFP_KERNEL);
477 if (unlikely(!ih))
478 return ERR_PTR(-ENOMEM);
479
480 idr_init(&ih->idr);
481 INIT_LIST_HEAD(&ih->watches);
482 mutex_init(&ih->mutex);
483 ih->last_wd = 0;
484 ih->in_ops = ops;
485 atomic_set(&ih->count, 0);
486 get_inotify_handle(ih);
487
488 return ih;
489}
490EXPORT_SYMBOL_GPL(inotify_init);
491
492/**
493 * inotify_init_watch - initialize an inotify watch
494 * @watch: watch to initialize
495 */
496void inotify_init_watch(struct inotify_watch *watch)
497{
498 INIT_LIST_HEAD(&watch->h_list);
499 INIT_LIST_HEAD(&watch->i_list);
500 atomic_set(&watch->count, 0);
501 get_inotify_watch(watch); /* initial get */
502}
503EXPORT_SYMBOL_GPL(inotify_init_watch);
504
505/*
506 * Watch removals suck violently. To kick the watch out we need (in this
507 * order) inode->inotify_mutex and ih->mutex. That's fine if we have
508 * a hold on inode; however, for all other cases we need to make damn sure
509 * we don't race with umount. We can *NOT* just grab a reference to a
510 * watch - inotify_unmount_inodes() will happily sail past it and we'll end
511 * with reference to inode potentially outliving its superblock. Ideally
512 * we just want to grab an active reference to superblock if we can; that
513 * will make sure we won't go into inotify_umount_inodes() until we are
514 * done. Cleanup is just deactivate_super(). However, that leaves a messy
515 * case - what if we *are* racing with umount() and active references to
516 * superblock can't be acquired anymore? We can bump ->s_count, grab
517 * ->s_umount, which will almost certainly wait until the superblock is shut
518 * down and the watch in question is pining for fjords. That's fine, but
519 * there is a problem - we might have hit the window between ->s_active
520 * getting to 0 / ->s_count - below S_BIAS (i.e. the moment when superblock
521 * is past the point of no return and is heading for shutdown) and the
522 * moment when deactivate_super() acquires ->s_umount. We could just do
523 * drop_super() yield() and retry, but that's rather antisocial and this
524 * stuff is luser-triggerable. OTOH, having grabbed ->s_umount and having
525 * found that we'd got there first (i.e. that ->s_root is non-NULL) we know
526 * that we won't race with inotify_umount_inodes(). So we could grab a
527 * reference to watch and do the rest as above, just with drop_super() instead
528 * of deactivate_super(), right? Wrong. We had to drop ih->mutex before we
529 * could grab ->s_umount. So the watch could've been gone already.
530 *
531 * That still can be dealt with - we need to save watch->wd, do idr_find()
532 * and compare its result with our pointer. If they match, we either have
533 * the damn thing still alive or we'd lost not one but two races at once,
534 * the watch had been killed and a new one got created with the same ->wd
535 * at the same address. That couldn't have happened in inotify_destroy(),
536 * but inotify_rm_wd() could run into that. Still, "new one got created"
537 * is not a problem - we have every right to kill it or leave it alone,
538 * whatever's more convenient.
539 *
540 * So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
541 * "grab it and kill it" check. If it's been our original watch, we are
542 * fine, if it's a newcomer - nevermind, just pretend that we'd won the
543 * race and kill the fscker anyway; we are safe since we know that its
544 * superblock won't be going away.
545 *
546 * And yes, this is far beyond mere "not very pretty"; so's the entire
547 * concept of inotify to start with.
548 */
549
550/**
551 * pin_to_kill - pin the watch down for removal
552 * @ih: inotify handle
553 * @watch: watch to kill
554 *
555 * Called with ih->mutex held, drops it. Possible return values:
556 * 0 - nothing to do, it has died
557 * 1 - remove it, drop the reference and deactivate_super()
558 * 2 - remove it, drop the reference and drop_super(); we tried hard to avoid
559 * that variant, since it involved a lot of PITA, but that's the best that
560 * could've been done.
561 */
562static int pin_to_kill(struct inotify_handle *ih, struct inotify_watch *watch)
563{
564 struct super_block *sb = watch->inode->i_sb;
565 s32 wd = watch->wd;
566
567 spin_lock(&sb_lock);
568 if (sb->s_count >= S_BIAS) {
569 atomic_inc(&sb->s_active);
570 spin_unlock(&sb_lock);
571 get_inotify_watch(watch);
572 mutex_unlock(&ih->mutex);
573 return 1; /* the best outcome */
574 }
575 sb->s_count++;
576 spin_unlock(&sb_lock);
577 mutex_unlock(&ih->mutex); /* can't grab ->s_umount under it */
578 down_read(&sb->s_umount);
579 if (likely(!sb->s_root)) {
580 /* fs is already shut down; the watch is dead */
581 drop_super(sb);
582 return 0;
583 }
584 /* raced with the final deactivate_super() */
585 mutex_lock(&ih->mutex);
586 if (idr_find(&ih->idr, wd) != watch || watch->inode->i_sb != sb) {
587 /* the watch is dead */
588 mutex_unlock(&ih->mutex);
589 drop_super(sb);
590 return 0;
591 }
592 /* still alive or freed and reused with the same sb and wd; kill */
593 get_inotify_watch(watch);
594 mutex_unlock(&ih->mutex);
595 return 2;
596}
597
598static void unpin_and_kill(struct inotify_watch *watch, int how)
599{
600 struct super_block *sb = watch->inode->i_sb;
601 put_inotify_watch(watch);
602 switch (how) {
603 case 1:
604 deactivate_super(sb);
605 break;
606 case 2:
607 drop_super(sb);
608 }
609}
610
611/**
612 * inotify_destroy - clean up and destroy an inotify instance
613 * @ih: inotify handle
614 */
615void inotify_destroy(struct inotify_handle *ih)
616{
617 /*
618 * Destroy all of the watches for this handle. Unfortunately, not very
619 * pretty. We cannot do a simple iteration over the list, because we
620 * do not know the inode until we iterate to the watch. But we need to
621 * hold inode->inotify_mutex before ih->mutex. The following works.
622 *
623 * AV: it had to become even uglier to start working ;-/
624 */
625 while (1) {
626 struct inotify_watch *watch;
627 struct list_head *watches;
628 struct super_block *sb;
629 struct inode *inode;
630 int how;
631
632 mutex_lock(&ih->mutex);
633 watches = &ih->watches;
634 if (list_empty(watches)) {
635 mutex_unlock(&ih->mutex);
636 break;
637 }
638 watch = list_first_entry(watches, struct inotify_watch, h_list);
639 sb = watch->inode->i_sb;
640 how = pin_to_kill(ih, watch);
641 if (!how)
642 continue;
643
644 inode = watch->inode;
645 mutex_lock(&inode->inotify_mutex);
646 mutex_lock(&ih->mutex);
647
648 /* make sure we didn't race with another list removal */
649 if (likely(idr_find(&ih->idr, watch->wd))) {
650 remove_watch_no_event(watch, ih);
651 put_inotify_watch(watch);
652 }
653
654 mutex_unlock(&ih->mutex);
655 mutex_unlock(&inode->inotify_mutex);
656 unpin_and_kill(watch, how);
657 }
658
659 /* free this handle: the put matching the get in inotify_init() */
660 put_inotify_handle(ih);
661}
662EXPORT_SYMBOL_GPL(inotify_destroy);
663
664/**
665 * inotify_find_watch - find an existing watch for an (ih,inode) pair
666 * @ih: inotify handle
667 * @inode: inode to watch
668 * @watchp: pointer to existing inotify_watch
669 *
670 * Caller must pin given inode (via nameidata).
671 */
672s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode,
673 struct inotify_watch **watchp)
674{
675 struct inotify_watch *old;
676 int ret = -ENOENT;
677
678 mutex_lock(&inode->inotify_mutex);
679 mutex_lock(&ih->mutex);
680
681 old = inode_find_handle(inode, ih);
682 if (unlikely(old)) {
683 get_inotify_watch(old); /* caller must put watch */
684 *watchp = old;
685 ret = old->wd;
686 }
687
688 mutex_unlock(&ih->mutex);
689 mutex_unlock(&inode->inotify_mutex);
690
691 return ret;
692}
693EXPORT_SYMBOL_GPL(inotify_find_watch);
694
695/**
696 * inotify_find_update_watch - find and update the mask of an existing watch
697 * @ih: inotify handle
698 * @inode: inode's watch to update
699 * @mask: mask of events to watch
700 *
701 * Caller must pin given inode (via nameidata).
702 */
703s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode,
704 u32 mask)
705{
706 struct inotify_watch *old;
707 int mask_add = 0;
708 int ret;
709
710 if (mask & IN_MASK_ADD)
711 mask_add = 1;
712
713 /* don't allow invalid bits: we don't want flags set */
714 mask &= IN_ALL_EVENTS | IN_ONESHOT;
715 if (unlikely(!mask))
716 return -EINVAL;
717
718 mutex_lock(&inode->inotify_mutex);
719 mutex_lock(&ih->mutex);
720
721 /*
722 * Handle the case of re-adding a watch on an (inode,ih) pair that we
723 * are already watching. We just update the mask and return its wd.
724 */
725 old = inode_find_handle(inode, ih);
726 if (unlikely(!old)) {
727 ret = -ENOENT;
728 goto out;
729 }
730
731 if (mask_add)
732 old->mask |= mask;
733 else
734 old->mask = mask;
735 ret = old->wd;
736out:
737 mutex_unlock(&ih->mutex);
738 mutex_unlock(&inode->inotify_mutex);
739 return ret;
740}
741EXPORT_SYMBOL_GPL(inotify_find_update_watch);
742
743/**
744 * inotify_add_watch - add a watch to an inotify instance
745 * @ih: inotify handle
746 * @watch: caller allocated watch structure
747 * @inode: inode to watch
748 * @mask: mask of events to watch
749 *
750 * Caller must pin given inode (via nameidata).
751 * Caller must ensure it only calls inotify_add_watch() once per watch.
752 * Calls inotify_handle_get_wd() so may sleep.
753 */
754s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch,
755 struct inode *inode, u32 mask)
756{
757 int ret = 0;
758 int newly_watched;
759
760 /* don't allow invalid bits: we don't want flags set */
761 mask &= IN_ALL_EVENTS | IN_ONESHOT;
762 if (unlikely(!mask))
763 return -EINVAL;
764 watch->mask = mask;
765
766 mutex_lock(&inode->inotify_mutex);
767 mutex_lock(&ih->mutex);
768
769 /* Initialize a new watch */
770 ret = inotify_handle_get_wd(ih, watch);
771 if (unlikely(ret))
772 goto out;
773 ret = watch->wd;
774
775 /* save a reference to handle and bump the count to make it official */
776 get_inotify_handle(ih);
777 watch->ih = ih;
778
779 /*
780 * Save a reference to the inode and bump the ref count to make it
781 * official. We hold a reference to nameidata, which makes this safe.
782 */
783 watch->inode = igrab(inode);
784
785 /* Add the watch to the handle's and the inode's list */
786 newly_watched = !inotify_inode_watched(inode);
787 list_add(&watch->h_list, &ih->watches);
788 list_add(&watch->i_list, &inode->inotify_watches);
789 /*
790 * Set child flags _after_ adding the watch, so there is no race
791 * windows where newly instantiated children could miss their parent's
792 * watched flag.
793 */
794 if (newly_watched)
795 set_dentry_child_flags(inode, 1);
796
797out:
798 mutex_unlock(&ih->mutex);
799 mutex_unlock(&inode->inotify_mutex);
800 return ret;
801}
802EXPORT_SYMBOL_GPL(inotify_add_watch);
803
804/**
805 * inotify_clone_watch - put the watch next to existing one
806 * @old: already installed watch
807 * @new: new watch
808 *
809 * Caller must hold the inotify_mutex of inode we are dealing with;
810 * it is expected to remove the old watch before unlocking the inode.
811 */
812s32 inotify_clone_watch(struct inotify_watch *old, struct inotify_watch *new)
813{
814 struct inotify_handle *ih = old->ih;
815 int ret = 0;
816
817 new->mask = old->mask;
818 new->ih = ih;
819
820 mutex_lock(&ih->mutex);
821
822 /* Initialize a new watch */
823 ret = inotify_handle_get_wd(ih, new);
824 if (unlikely(ret))
825 goto out;
826 ret = new->wd;
827
828 get_inotify_handle(ih);
829
830 new->inode = igrab(old->inode);
831
832 list_add(&new->h_list, &ih->watches);
833 list_add(&new->i_list, &old->inode->inotify_watches);
834out:
835 mutex_unlock(&ih->mutex);
836 return ret;
837}
838
839void inotify_evict_watch(struct inotify_watch *watch)
840{
841 get_inotify_watch(watch);
842 mutex_lock(&watch->ih->mutex);
843 inotify_remove_watch_locked(watch->ih, watch);
844 mutex_unlock(&watch->ih->mutex);
845}
846
847/**
848 * inotify_rm_wd - remove a watch from an inotify instance
849 * @ih: inotify handle
850 * @wd: watch descriptor to remove
851 *
852 * Can sleep.
853 */
854int inotify_rm_wd(struct inotify_handle *ih, u32 wd)
855{
856 struct inotify_watch *watch;
857 struct super_block *sb;
858 struct inode *inode;
859 int how;
860
861 mutex_lock(&ih->mutex);
862 watch = idr_find(&ih->idr, wd);
863 if (unlikely(!watch)) {
864 mutex_unlock(&ih->mutex);
865 return -EINVAL;
866 }
867 sb = watch->inode->i_sb;
868 how = pin_to_kill(ih, watch);
869 if (!how)
870 return 0;
871
872 inode = watch->inode;
873
874 mutex_lock(&inode->inotify_mutex);
875 mutex_lock(&ih->mutex);
876
877 /* make sure that we did not race */
878 if (likely(idr_find(&ih->idr, wd) == watch))
879 inotify_remove_watch_locked(ih, watch);
880
881 mutex_unlock(&ih->mutex);
882 mutex_unlock(&inode->inotify_mutex);
883 unpin_and_kill(watch, how);
884
885 return 0;
886}
887EXPORT_SYMBOL_GPL(inotify_rm_wd);
888
889/**
890 * inotify_rm_watch - remove a watch from an inotify instance
891 * @ih: inotify handle
892 * @watch: watch to remove
893 *
894 * Can sleep.
895 */
896int inotify_rm_watch(struct inotify_handle *ih,
897 struct inotify_watch *watch)
898{
899 return inotify_rm_wd(ih, watch->wd);
900}
901EXPORT_SYMBOL_GPL(inotify_rm_watch);
902
903/*
904 * inotify_setup - core initialization function
905 */
906static int __init inotify_setup(void)
907{
908 atomic_set(&inotify_cookie, 0);
909
910 return 0;
911}
912
913module_init(inotify_setup);
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
new file mode 100644
index 000000000000..bed766e435b5
--- /dev/null
+++ b/fs/notify/inotify/inotify_user.c
@@ -0,0 +1,792 @@
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 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2, or (at your option) any
14 * later version.
15 *
16 * This program is distributed in the hope that it will be useful, but
17 * WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * General Public License for more details.
20 */
21
22#include <linux/kernel.h>
23#include <linux/sched.h>
24#include <linux/slab.h>
25#include <linux/fs.h>
26#include <linux/file.h>
27#include <linux/mount.h>
28#include <linux/namei.h>
29#include <linux/poll.h>
30#include <linux/init.h>
31#include <linux/list.h>
32#include <linux/inotify.h>
33#include <linux/syscalls.h>
34#include <linux/magic.h>
35
36#include <asm/ioctls.h>
37
38static struct kmem_cache *watch_cachep __read_mostly;
39static struct kmem_cache *event_cachep __read_mostly;
40
41static struct vfsmount *inotify_mnt __read_mostly;
42
43/* these are configurable via /proc/sys/fs/inotify/ */
44static int inotify_max_user_instances __read_mostly;
45static int inotify_max_user_watches __read_mostly;
46static int inotify_max_queued_events __read_mostly;
47
48/*
49 * Lock ordering:
50 *
51 * inotify_dev->up_mutex (ensures we don't re-add the same watch)
52 * inode->inotify_mutex (protects inode's watch list)
53 * inotify_handle->mutex (protects inotify_handle's watch list)
54 * inotify_dev->ev_mutex (protects device's event queue)
55 */
56
57/*
58 * Lifetimes of the main data structures:
59 *
60 * inotify_device: Lifetime is managed by reference count, from
61 * sys_inotify_init() until release. Additional references can bump the count
62 * via get_inotify_dev() and drop the count via put_inotify_dev().
63 *
64 * inotify_user_watch: Lifetime is from create_watch() to the receipt of an
65 * IN_IGNORED event from inotify, or when using IN_ONESHOT, to receipt of the
66 * first event, or to inotify_destroy().
67 */
68
69/*
70 * struct inotify_device - represents an inotify instance
71 *
72 * This structure is protected by the mutex 'mutex'.
73 */
74struct inotify_device {
75 wait_queue_head_t wq; /* wait queue for i/o */
76 struct mutex ev_mutex; /* protects event queue */
77 struct mutex up_mutex; /* synchronizes watch updates */
78 struct list_head events; /* list of queued events */
79 struct user_struct *user; /* user who opened this dev */
80 struct inotify_handle *ih; /* inotify handle */
81 struct fasync_struct *fa; /* async notification */
82 atomic_t count; /* reference count */
83 unsigned int queue_size; /* size of the queue (bytes) */
84 unsigned int event_count; /* number of pending events */
85 unsigned int max_events; /* maximum number of events */
86};
87
88/*
89 * struct inotify_kernel_event - An inotify event, originating from a watch and
90 * queued for user-space. A list of these is attached to each instance of the
91 * device. In read(), this list is walked and all events that can fit in the
92 * buffer are returned.
93 *
94 * Protected by dev->ev_mutex of the device in which we are queued.
95 */
96struct inotify_kernel_event {
97 struct inotify_event event; /* the user-space event */
98 struct list_head list; /* entry in inotify_device's list */
99 char *name; /* filename, if any */
100};
101
102/*
103 * struct inotify_user_watch - our version of an inotify_watch, we add
104 * a reference to the associated inotify_device.
105 */
106struct inotify_user_watch {
107 struct inotify_device *dev; /* associated device */
108 struct inotify_watch wdata; /* inotify watch data */
109};
110
111#ifdef CONFIG_SYSCTL
112
113#include <linux/sysctl.h>
114
115static int zero;
116
117ctl_table inotify_table[] = {
118 {
119 .ctl_name = INOTIFY_MAX_USER_INSTANCES,
120 .procname = "max_user_instances",
121 .data = &inotify_max_user_instances,
122 .maxlen = sizeof(int),
123 .mode = 0644,
124 .proc_handler = &proc_dointvec_minmax,
125 .strategy = &sysctl_intvec,
126 .extra1 = &zero,
127 },
128 {
129 .ctl_name = INOTIFY_MAX_USER_WATCHES,
130 .procname = "max_user_watches",
131 .data = &inotify_max_user_watches,
132 .maxlen = sizeof(int),
133 .mode = 0644,
134 .proc_handler = &proc_dointvec_minmax,
135 .strategy = &sysctl_intvec,
136 .extra1 = &zero,
137 },
138 {
139 .ctl_name = INOTIFY_MAX_QUEUED_EVENTS,
140 .procname = "max_queued_events",
141 .data = &inotify_max_queued_events,
142 .maxlen = sizeof(int),
143 .mode = 0644,
144 .proc_handler = &proc_dointvec_minmax,
145 .strategy = &sysctl_intvec,
146 .extra1 = &zero
147 },
148 { .ctl_name = 0 }
149};
150#endif /* CONFIG_SYSCTL */
151
152static inline void get_inotify_dev(struct inotify_device *dev)
153{
154 atomic_inc(&dev->count);
155}
156
157static inline void put_inotify_dev(struct inotify_device *dev)
158{
159 if (atomic_dec_and_test(&dev->count)) {
160 atomic_dec(&dev->user->inotify_devs);
161 free_uid(dev->user);
162 kfree(dev);
163 }
164}
165
166/*
167 * free_inotify_user_watch - cleans up the watch and its references
168 */
169static void free_inotify_user_watch(struct inotify_watch *w)
170{
171 struct inotify_user_watch *watch;
172 struct inotify_device *dev;
173
174 watch = container_of(w, struct inotify_user_watch, wdata);
175 dev = watch->dev;
176
177 atomic_dec(&dev->user->inotify_watches);
178 put_inotify_dev(dev);
179 kmem_cache_free(watch_cachep, watch);
180}
181
182/*
183 * kernel_event - create a new kernel event with the given parameters
184 *
185 * This function can sleep.
186 */
187static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie,
188 const char *name)
189{
190 struct inotify_kernel_event *kevent;
191
192 kevent = kmem_cache_alloc(event_cachep, GFP_NOFS);
193 if (unlikely(!kevent))
194 return NULL;
195
196 /* we hand this out to user-space, so zero it just in case */
197 memset(&kevent->event, 0, sizeof(struct inotify_event));
198
199 kevent->event.wd = wd;
200 kevent->event.mask = mask;
201 kevent->event.cookie = cookie;
202
203 INIT_LIST_HEAD(&kevent->list);
204
205 if (name) {
206 size_t len, rem, event_size = sizeof(struct inotify_event);
207
208 /*
209 * We need to pad the filename so as to properly align an
210 * array of inotify_event structures. Because the structure is
211 * small and the common case is a small filename, we just round
212 * up to the next multiple of the structure's sizeof. This is
213 * simple and safe for all architectures.
214 */
215 len = strlen(name) + 1;
216 rem = event_size - len;
217 if (len > event_size) {
218 rem = event_size - (len % event_size);
219 if (len % event_size == 0)
220 rem = 0;
221 }
222
223 kevent->name = kmalloc(len + rem, GFP_KERNEL);
224 if (unlikely(!kevent->name)) {
225 kmem_cache_free(event_cachep, kevent);
226 return NULL;
227 }
228 memcpy(kevent->name, name, len);
229 if (rem)
230 memset(kevent->name + len, 0, rem);
231 kevent->event.len = len + rem;
232 } else {
233 kevent->event.len = 0;
234 kevent->name = NULL;
235 }
236
237 return kevent;
238}
239
240/*
241 * inotify_dev_get_event - return the next event in the given dev's queue
242 *
243 * Caller must hold dev->ev_mutex.
244 */
245static inline struct inotify_kernel_event *
246inotify_dev_get_event(struct inotify_device *dev)
247{
248 return list_entry(dev->events.next, struct inotify_kernel_event, list);
249}
250
251/*
252 * inotify_dev_get_last_event - return the last event in the given dev's queue
253 *
254 * Caller must hold dev->ev_mutex.
255 */
256static inline struct inotify_kernel_event *
257inotify_dev_get_last_event(struct inotify_device *dev)
258{
259 if (list_empty(&dev->events))
260 return NULL;
261 return list_entry(dev->events.prev, struct inotify_kernel_event, list);
262}
263
264/*
265 * inotify_dev_queue_event - event handler registered with core inotify, adds
266 * a new event to the given device
267 *
268 * Can sleep (calls kernel_event()).
269 */
270static void inotify_dev_queue_event(struct inotify_watch *w, u32 wd, u32 mask,
271 u32 cookie, const char *name,
272 struct inode *ignored)
273{
274 struct inotify_user_watch *watch;
275 struct inotify_device *dev;
276 struct inotify_kernel_event *kevent, *last;
277
278 watch = container_of(w, struct inotify_user_watch, wdata);
279 dev = watch->dev;
280
281 mutex_lock(&dev->ev_mutex);
282
283 /* we can safely put the watch as we don't reference it while
284 * generating the event
285 */
286 if (mask & IN_IGNORED || w->mask & IN_ONESHOT)
287 put_inotify_watch(w); /* final put */
288
289 /* coalescing: drop this event if it is a dupe of the previous */
290 last = inotify_dev_get_last_event(dev);
291 if (last && last->event.mask == mask && last->event.wd == wd &&
292 last->event.cookie == cookie) {
293 const char *lastname = last->name;
294
295 if (!name && !lastname)
296 goto out;
297 if (name && lastname && !strcmp(lastname, name))
298 goto out;
299 }
300
301 /* the queue overflowed and we already sent the Q_OVERFLOW event */
302 if (unlikely(dev->event_count > dev->max_events))
303 goto out;
304
305 /* if the queue overflows, we need to notify user space */
306 if (unlikely(dev->event_count == dev->max_events))
307 kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL);
308 else
309 kevent = kernel_event(wd, mask, cookie, name);
310
311 if (unlikely(!kevent))
312 goto out;
313
314 /* queue the event and wake up anyone waiting */
315 dev->event_count++;
316 dev->queue_size += sizeof(struct inotify_event) + kevent->event.len;
317 list_add_tail(&kevent->list, &dev->events);
318 wake_up_interruptible(&dev->wq);
319 kill_fasync(&dev->fa, SIGIO, POLL_IN);
320
321out:
322 mutex_unlock(&dev->ev_mutex);
323}
324
325/*
326 * remove_kevent - cleans up the given kevent
327 *
328 * Caller must hold dev->ev_mutex.
329 */
330static void remove_kevent(struct inotify_device *dev,
331 struct inotify_kernel_event *kevent)
332{
333 list_del(&kevent->list);
334
335 dev->event_count--;
336 dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len;
337}
338
339/*
340 * free_kevent - frees the given kevent.
341 */
342static void free_kevent(struct inotify_kernel_event *kevent)
343{
344 kfree(kevent->name);
345 kmem_cache_free(event_cachep, kevent);
346}
347
348/*
349 * inotify_dev_event_dequeue - destroy an event on the given device
350 *
351 * Caller must hold dev->ev_mutex.
352 */
353static void inotify_dev_event_dequeue(struct inotify_device *dev)
354{
355 if (!list_empty(&dev->events)) {
356 struct inotify_kernel_event *kevent;
357 kevent = inotify_dev_get_event(dev);
358 remove_kevent(dev, kevent);
359 free_kevent(kevent);
360 }
361}
362
363/*
364 * find_inode - resolve a user-given path to a specific inode
365 */
366static int find_inode(const char __user *dirname, struct path *path,
367 unsigned flags)
368{
369 int error;
370
371 error = user_path_at(AT_FDCWD, dirname, flags, path);
372 if (error)
373 return error;
374 /* you can only watch an inode if you have read permissions on it */
375 error = inode_permission(path->dentry->d_inode, MAY_READ);
376 if (error)
377 path_put(path);
378 return error;
379}
380
381/*
382 * create_watch - creates a watch on the given device.
383 *
384 * Callers must hold dev->up_mutex.
385 */
386static int create_watch(struct inotify_device *dev, struct inode *inode,
387 u32 mask)
388{
389 struct inotify_user_watch *watch;
390 int ret;
391
392 if (atomic_read(&dev->user->inotify_watches) >=
393 inotify_max_user_watches)
394 return -ENOSPC;
395
396 watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL);
397 if (unlikely(!watch))
398 return -ENOMEM;
399
400 /* save a reference to device and bump the count to make it official */
401 get_inotify_dev(dev);
402 watch->dev = dev;
403
404 atomic_inc(&dev->user->inotify_watches);
405
406 inotify_init_watch(&watch->wdata);
407 ret = inotify_add_watch(dev->ih, &watch->wdata, inode, mask);
408 if (ret < 0)
409 free_inotify_user_watch(&watch->wdata);
410
411 return ret;
412}
413
414/* Device Interface */
415
416static unsigned int inotify_poll(struct file *file, poll_table *wait)
417{
418 struct inotify_device *dev = file->private_data;
419 int ret = 0;
420
421 poll_wait(file, &dev->wq, wait);
422 mutex_lock(&dev->ev_mutex);
423 if (!list_empty(&dev->events))
424 ret = POLLIN | POLLRDNORM;
425 mutex_unlock(&dev->ev_mutex);
426
427 return ret;
428}
429
430/*
431 * Get an inotify_kernel_event if one exists and is small
432 * enough to fit in "count". Return an error pointer if
433 * not large enough.
434 *
435 * Called with the device ev_mutex held.
436 */
437static struct inotify_kernel_event *get_one_event(struct inotify_device *dev,
438 size_t count)
439{
440 size_t event_size = sizeof(struct inotify_event);
441 struct inotify_kernel_event *kevent;
442
443 if (list_empty(&dev->events))
444 return NULL;
445
446 kevent = inotify_dev_get_event(dev);
447 if (kevent->name)
448 event_size += kevent->event.len;
449
450 if (event_size > count)
451 return ERR_PTR(-EINVAL);
452
453 remove_kevent(dev, kevent);
454 return kevent;
455}
456
457/*
458 * Copy an event to user space, returning how much we copied.
459 *
460 * We already checked that the event size is smaller than the
461 * buffer we had in "get_one_event()" above.
462 */
463static ssize_t copy_event_to_user(struct inotify_kernel_event *kevent,
464 char __user *buf)
465{
466 size_t event_size = sizeof(struct inotify_event);
467
468 if (copy_to_user(buf, &kevent->event, event_size))
469 return -EFAULT;
470
471 if (kevent->name) {
472 buf += event_size;
473
474 if (copy_to_user(buf, kevent->name, kevent->event.len))
475 return -EFAULT;
476
477 event_size += kevent->event.len;
478 }
479 return event_size;
480}
481
482static ssize_t inotify_read(struct file *file, char __user *buf,
483 size_t count, loff_t *pos)
484{
485 struct inotify_device *dev;
486 char __user *start;
487 int ret;
488 DEFINE_WAIT(wait);
489
490 start = buf;
491 dev = file->private_data;
492
493 while (1) {
494 struct inotify_kernel_event *kevent;
495
496 prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE);
497
498 mutex_lock(&dev->ev_mutex);
499 kevent = get_one_event(dev, count);
500 mutex_unlock(&dev->ev_mutex);
501
502 if (kevent) {
503 ret = PTR_ERR(kevent);
504 if (IS_ERR(kevent))
505 break;
506 ret = copy_event_to_user(kevent, buf);
507 free_kevent(kevent);
508 if (ret < 0)
509 break;
510 buf += ret;
511 count -= ret;
512 continue;
513 }
514
515 ret = -EAGAIN;
516 if (file->f_flags & O_NONBLOCK)
517 break;
518 ret = -EINTR;
519 if (signal_pending(current))
520 break;
521
522 if (start != buf)
523 break;
524
525 schedule();
526 }
527
528 finish_wait(&dev->wq, &wait);
529 if (start != buf && ret != -EFAULT)
530 ret = buf - start;
531 return ret;
532}
533
534static int inotify_fasync(int fd, struct file *file, int on)
535{
536 struct inotify_device *dev = file->private_data;
537
538 return fasync_helper(fd, file, on, &dev->fa) >= 0 ? 0 : -EIO;
539}
540
541static int inotify_release(struct inode *ignored, struct file *file)
542{
543 struct inotify_device *dev = file->private_data;
544
545 inotify_destroy(dev->ih);
546
547 /* destroy all of the events on this device */
548 mutex_lock(&dev->ev_mutex);
549 while (!list_empty(&dev->events))
550 inotify_dev_event_dequeue(dev);
551 mutex_unlock(&dev->ev_mutex);
552
553 /* free this device: the put matching the get in inotify_init() */
554 put_inotify_dev(dev);
555
556 return 0;
557}
558
559static long inotify_ioctl(struct file *file, unsigned int cmd,
560 unsigned long arg)
561{
562 struct inotify_device *dev;
563 void __user *p;
564 int ret = -ENOTTY;
565
566 dev = file->private_data;
567 p = (void __user *) arg;
568
569 switch (cmd) {
570 case FIONREAD:
571 ret = put_user(dev->queue_size, (int __user *) p);
572 break;
573 }
574
575 return ret;
576}
577
578static const struct file_operations inotify_fops = {
579 .poll = inotify_poll,
580 .read = inotify_read,
581 .fasync = inotify_fasync,
582 .release = inotify_release,
583 .unlocked_ioctl = inotify_ioctl,
584 .compat_ioctl = inotify_ioctl,
585};
586
587static const struct inotify_operations inotify_user_ops = {
588 .handle_event = inotify_dev_queue_event,
589 .destroy_watch = free_inotify_user_watch,
590};
591
592SYSCALL_DEFINE1(inotify_init1, int, flags)
593{
594 struct inotify_device *dev;
595 struct inotify_handle *ih;
596 struct user_struct *user;
597 struct file *filp;
598 int fd, ret;
599
600 /* Check the IN_* constants for consistency. */
601 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
602 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
603
604 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
605 return -EINVAL;
606
607 fd = get_unused_fd_flags(flags & O_CLOEXEC);
608 if (fd < 0)
609 return fd;
610
611 filp = get_empty_filp();
612 if (!filp) {
613 ret = -ENFILE;
614 goto out_put_fd;
615 }
616
617 user = get_current_user();
618 if (unlikely(atomic_read(&user->inotify_devs) >=
619 inotify_max_user_instances)) {
620 ret = -EMFILE;
621 goto out_free_uid;
622 }
623
624 dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL);
625 if (unlikely(!dev)) {
626 ret = -ENOMEM;
627 goto out_free_uid;
628 }
629
630 ih = inotify_init(&inotify_user_ops);
631 if (IS_ERR(ih)) {
632 ret = PTR_ERR(ih);
633 goto out_free_dev;
634 }
635 dev->ih = ih;
636 dev->fa = NULL;
637
638 filp->f_op = &inotify_fops;
639 filp->f_path.mnt = mntget(inotify_mnt);
640 filp->f_path.dentry = dget(inotify_mnt->mnt_root);
641 filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping;
642 filp->f_mode = FMODE_READ;
643 filp->f_flags = O_RDONLY | (flags & O_NONBLOCK);
644 filp->private_data = dev;
645
646 INIT_LIST_HEAD(&dev->events);
647 init_waitqueue_head(&dev->wq);
648 mutex_init(&dev->ev_mutex);
649 mutex_init(&dev->up_mutex);
650 dev->event_count = 0;
651 dev->queue_size = 0;
652 dev->max_events = inotify_max_queued_events;
653 dev->user = user;
654 atomic_set(&dev->count, 0);
655
656 get_inotify_dev(dev);
657 atomic_inc(&user->inotify_devs);
658 fd_install(fd, filp);
659
660 return fd;
661out_free_dev:
662 kfree(dev);
663out_free_uid:
664 free_uid(user);
665 put_filp(filp);
666out_put_fd:
667 put_unused_fd(fd);
668 return ret;
669}
670
671SYSCALL_DEFINE0(inotify_init)
672{
673 return sys_inotify_init1(0);
674}
675
676SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
677 u32, mask)
678{
679 struct inode *inode;
680 struct inotify_device *dev;
681 struct path path;
682 struct file *filp;
683 int ret, fput_needed;
684 unsigned flags = 0;
685
686 filp = fget_light(fd, &fput_needed);
687 if (unlikely(!filp))
688 return -EBADF;
689
690 /* verify that this is indeed an inotify instance */
691 if (unlikely(filp->f_op != &inotify_fops)) {
692 ret = -EINVAL;
693 goto fput_and_out;
694 }
695
696 if (!(mask & IN_DONT_FOLLOW))
697 flags |= LOOKUP_FOLLOW;
698 if (mask & IN_ONLYDIR)
699 flags |= LOOKUP_DIRECTORY;
700
701 ret = find_inode(pathname, &path, flags);
702 if (unlikely(ret))
703 goto fput_and_out;
704
705 /* inode held in place by reference to path; dev by fget on fd */
706 inode = path.dentry->d_inode;
707 dev = filp->private_data;
708
709 mutex_lock(&dev->up_mutex);
710 ret = inotify_find_update_watch(dev->ih, inode, mask);
711 if (ret == -ENOENT)
712 ret = create_watch(dev, inode, mask);
713 mutex_unlock(&dev->up_mutex);
714
715 path_put(&path);
716fput_and_out:
717 fput_light(filp, fput_needed);
718 return ret;
719}
720
721SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
722{
723 struct file *filp;
724 struct inotify_device *dev;
725 int ret, fput_needed;
726
727 filp = fget_light(fd, &fput_needed);
728 if (unlikely(!filp))
729 return -EBADF;
730
731 /* verify that this is indeed an inotify instance */
732 if (unlikely(filp->f_op != &inotify_fops)) {
733 ret = -EINVAL;
734 goto out;
735 }
736
737 dev = filp->private_data;
738
739 /* we free our watch data when we get IN_IGNORED */
740 ret = inotify_rm_wd(dev->ih, wd);
741
742out:
743 fput_light(filp, fput_needed);
744 return ret;
745}
746
747static int
748inotify_get_sb(struct file_system_type *fs_type, int flags,
749 const char *dev_name, void *data, struct vfsmount *mnt)
750{
751 return get_sb_pseudo(fs_type, "inotify", NULL,
752 INOTIFYFS_SUPER_MAGIC, mnt);
753}
754
755static struct file_system_type inotify_fs_type = {
756 .name = "inotifyfs",
757 .get_sb = inotify_get_sb,
758 .kill_sb = kill_anon_super,
759};
760
761/*
762 * inotify_user_setup - Our initialization function. Note that we cannnot return
763 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
764 * must result in panic().
765 */
766static int __init inotify_user_setup(void)
767{
768 int ret;
769
770 ret = register_filesystem(&inotify_fs_type);
771 if (unlikely(ret))
772 panic("inotify: register_filesystem returned %d!\n", ret);
773
774 inotify_mnt = kern_mount(&inotify_fs_type);
775 if (IS_ERR(inotify_mnt))
776 panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt));
777
778 inotify_max_queued_events = 16384;
779 inotify_max_user_instances = 128;
780 inotify_max_user_watches = 8192;
781
782 watch_cachep = kmem_cache_create("inotify_watch_cache",
783 sizeof(struct inotify_user_watch),
784 0, SLAB_PANIC, NULL);
785 event_cachep = kmem_cache_create("inotify_event_cache",
786 sizeof(struct inotify_kernel_event),
787 0, SLAB_PANIC, NULL);
788
789 return 0;
790}
791
792module_init(inotify_user_setup);
generated by cgit v1.2.2 (git 2.25.0) at 2024-10-02 18:42:03 -0400