blob: 7457501b95656087cfe27339b94d3bace7585782 [file] [log] [blame]
Robert Love0eeca282005-07-12 17:06:03 -04001/*
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 *
Amy Griffis2d9048e2006-06-01 13:10:59 -07008 * Kernel API added by: Amy Griffis <amy.griffis@hp.com>
9 *
Robert Love0eeca282005-07-12 17:06:03 -040010 * Copyright (C) 2005 John McCutchan
Amy Griffis2d9048e2006-06-01 13:10:59 -070011 * Copyright 2006 Hewlett-Packard Development Company, L.P.
Robert Love0eeca282005-07-12 17:06:03 -040012 *
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>
Robert Love0eeca282005-07-12 17:06:03 -040026#include <linux/spinlock.h>
27#include <linux/idr.h>
28#include <linux/slab.h>
29#include <linux/fs.h>
Al Viro914e2632006-10-18 13:55:46 -040030#include <linux/sched.h>
Robert Love0eeca282005-07-12 17:06:03 -040031#include <linux/init.h>
32#include <linux/list.h>
33#include <linux/writeback.h>
34#include <linux/inotify.h>
Robert Love0eeca282005-07-12 17:06:03 -040035
36static atomic_t inotify_cookie;
37
Robert Love0eeca282005-07-12 17:06:03 -040038/*
39 * Lock ordering:
40 *
41 * dentry->d_lock (used to keep d_move() away from dentry->d_parent)
Ingo Molnarf24075b2006-03-23 03:00:34 -080042 * iprune_mutex (synchronize shrink_icache_memory())
Robert Love0eeca282005-07-12 17:06:03 -040043 * inode_lock (protects the super_block->s_inodes list)
Ingo Molnard4f9af92006-03-23 03:00:30 -080044 * inode->inotify_mutex (protects inode->inotify_watches and watches->i_list)
Amy Griffis2d9048e2006-06-01 13:10:59 -070045 * 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.
Robert Love0eeca282005-07-12 17:06:03 -040051 */
52
53/*
Amy Griffis2d9048e2006-06-01 13:10:59 -070054 * Lifetimes of the three main data structures--inotify_handle, inode, and
Robert Love0eeca282005-07-12 17:06:03 -040055 * inotify_watch--are managed by reference count.
56 *
Amy Griffis2d9048e2006-06-01 13:10:59 -070057 * 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().
Robert Love0eeca282005-07-12 17:06:03 -040060 *
Amy Griffis2d9048e2006-06-01 13:10:59 -070061 * 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.
Robert Love0eeca282005-07-12 17:06:03 -040067 *
68 * inode: Pinned so long as the inode is associated with a watch, from
Amy Griffis2d9048e2006-06-01 13:10:59 -070069 * inotify_add_watch() to the final put_inotify_watch().
Robert Love0eeca282005-07-12 17:06:03 -040070 */
71
72/*
Amy Griffis2d9048e2006-06-01 13:10:59 -070073 * struct inotify_handle - represents an inotify instance
Robert Love0eeca282005-07-12 17:06:03 -040074 *
Ingo Molnard4f9af92006-03-23 03:00:30 -080075 * This structure is protected by the mutex 'mutex'.
Robert Love0eeca282005-07-12 17:06:03 -040076 */
Amy Griffis2d9048e2006-06-01 13:10:59 -070077struct inotify_handle {
Robert Love0eeca282005-07-12 17:06:03 -040078 struct idr idr; /* idr mapping wd -> watch */
Ingo Molnard4f9af92006-03-23 03:00:30 -080079 struct mutex mutex; /* protects this bad boy */
Robert Love0eeca282005-07-12 17:06:03 -040080 struct list_head watches; /* list of watches */
81 atomic_t count; /* reference count */
John McCutchanb9c55d22005-08-01 11:00:45 -040082 u32 last_wd; /* the last wd allocated */
Amy Griffis2d9048e2006-06-01 13:10:59 -070083 const struct inotify_operations *in_ops; /* inotify caller operations */
Robert Love0eeca282005-07-12 17:06:03 -040084};
85
Amy Griffis2d9048e2006-06-01 13:10:59 -070086static inline void get_inotify_handle(struct inotify_handle *ih)
Robert Love0eeca282005-07-12 17:06:03 -040087{
Amy Griffis2d9048e2006-06-01 13:10:59 -070088 atomic_inc(&ih->count);
Robert Love0eeca282005-07-12 17:06:03 -040089}
90
Amy Griffis2d9048e2006-06-01 13:10:59 -070091static inline void put_inotify_handle(struct inotify_handle *ih)
Robert Love0eeca282005-07-12 17:06:03 -040092{
Amy Griffis2d9048e2006-06-01 13:10:59 -070093 if (atomic_dec_and_test(&ih->count)) {
94 idr_destroy(&ih->idr);
95 kfree(ih);
Robert Love0eeca282005-07-12 17:06:03 -040096 }
97}
98
Amy Griffis2d9048e2006-06-01 13:10:59 -070099/**
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)
Robert Love0eeca282005-07-12 17:06:03 -0400104{
105 atomic_inc(&watch->count);
106}
Amy Griffis2d9048e2006-06-01 13:10:59 -0700107EXPORT_SYMBOL_GPL(get_inotify_watch);
Robert Love0eeca282005-07-12 17:06:03 -0400108
Amy Griffis2d9048e2006-06-01 13:10:59 -0700109/**
Robert Love0eeca282005-07-12 17:06:03 -0400110 * put_inotify_watch - decrements the ref count on a given watch. cleans up
Amy Griffis2d9048e2006-06-01 13:10:59 -0700111 * watch references if the count reaches zero. inotify_watch is freed by
112 * inotify callers via the destroy_watch() op.
113 * @watch: watch to release
Robert Love0eeca282005-07-12 17:06:03 -0400114 */
Amy Griffis2d9048e2006-06-01 13:10:59 -0700115void put_inotify_watch(struct inotify_watch *watch)
Robert Love0eeca282005-07-12 17:06:03 -0400116{
117 if (atomic_dec_and_test(&watch->count)) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700118 struct inotify_handle *ih = watch->ih;
119
Robert Love0eeca282005-07-12 17:06:03 -0400120 iput(watch->inode);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700121 ih->in_ops->destroy_watch(watch);
122 put_inotify_handle(ih);
Robert Love0eeca282005-07-12 17:06:03 -0400123 }
124}
Amy Griffis2d9048e2006-06-01 13:10:59 -0700125EXPORT_SYMBOL_GPL(put_inotify_watch);
Robert Love0eeca282005-07-12 17:06:03 -0400126
127/*
Amy Griffis2d9048e2006-06-01 13:10:59 -0700128 * inotify_handle_get_wd - returns the next WD for use by the given handle
Robert Love0eeca282005-07-12 17:06:03 -0400129 *
Amy Griffis2d9048e2006-06-01 13:10:59 -0700130 * Callers must hold ih->mutex. This function can sleep.
Robert Love0eeca282005-07-12 17:06:03 -0400131 */
Amy Griffis2d9048e2006-06-01 13:10:59 -0700132static int inotify_handle_get_wd(struct inotify_handle *ih,
133 struct inotify_watch *watch)
Robert Love0eeca282005-07-12 17:06:03 -0400134{
135 int ret;
136
137 do {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700138 if (unlikely(!idr_pre_get(&ih->idr, GFP_KERNEL)))
Robert Love0eeca282005-07-12 17:06:03 -0400139 return -ENOSPC;
Amy Griffis2d9048e2006-06-01 13:10:59 -0700140 ret = idr_get_new_above(&ih->idr, watch, ih->last_wd+1, &watch->wd);
Robert Love0eeca282005-07-12 17:06:03 -0400141 } while (ret == -EAGAIN);
142
Amy Griffis2d9048e2006-06-01 13:10:59 -0700143 if (likely(!ret))
144 ih->last_wd = watch->wd;
145
Robert Love0eeca282005-07-12 17:06:03 -0400146 return ret;
147}
148
149/*
Nick Pigginc32ccd82006-03-25 03:07:09 -0800150 * inotify_inode_watched - returns nonzero if there are watches on this inode
151 * and zero otherwise. We call this lockless, we do not care if we race.
152 */
153static inline int inotify_inode_watched(struct inode *inode)
154{
155 return !list_empty(&inode->inotify_watches);
156}
157
158/*
159 * Get child dentry flag into synch with parent inode.
160 * Flag should always be clear for negative dentrys.
161 */
162static void set_dentry_child_flags(struct inode *inode, int watched)
163{
164 struct dentry *alias;
165
166 spin_lock(&dcache_lock);
167 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
168 struct dentry *child;
169
170 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
171 if (!child->d_inode) {
172 WARN_ON(child->d_flags & DCACHE_INOTIFY_PARENT_WATCHED);
173 continue;
174 }
175 spin_lock(&child->d_lock);
176 if (watched) {
177 WARN_ON(child->d_flags &
178 DCACHE_INOTIFY_PARENT_WATCHED);
179 child->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
180 } else {
181 WARN_ON(!(child->d_flags &
182 DCACHE_INOTIFY_PARENT_WATCHED));
183 child->d_flags&=~DCACHE_INOTIFY_PARENT_WATCHED;
184 }
185 spin_unlock(&child->d_lock);
186 }
187 }
188 spin_unlock(&dcache_lock);
189}
190
191/*
Amy Griffis2d9048e2006-06-01 13:10:59 -0700192 * inotify_find_handle - find the watch associated with the given inode and
193 * handle
Robert Love0eeca282005-07-12 17:06:03 -0400194 *
Ingo Molnard4f9af92006-03-23 03:00:30 -0800195 * Callers must hold inode->inotify_mutex.
Robert Love0eeca282005-07-12 17:06:03 -0400196 */
Amy Griffis2d9048e2006-06-01 13:10:59 -0700197static struct inotify_watch *inode_find_handle(struct inode *inode,
198 struct inotify_handle *ih)
Robert Love0eeca282005-07-12 17:06:03 -0400199{
200 struct inotify_watch *watch;
201
202 list_for_each_entry(watch, &inode->inotify_watches, i_list) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700203 if (watch->ih == ih)
Robert Love0eeca282005-07-12 17:06:03 -0400204 return watch;
205 }
206
207 return NULL;
208}
209
210/*
Amy Griffis3ca10062006-06-01 13:11:05 -0700211 * remove_watch_no_event - remove watch without the IN_IGNORED event.
Amy Griffis2d9048e2006-06-01 13:10:59 -0700212 *
213 * Callers must hold both inode->inotify_mutex and ih->mutex.
Robert Love0eeca282005-07-12 17:06:03 -0400214 */
215static void remove_watch_no_event(struct inotify_watch *watch,
Amy Griffis2d9048e2006-06-01 13:10:59 -0700216 struct inotify_handle *ih)
Robert Love0eeca282005-07-12 17:06:03 -0400217{
218 list_del(&watch->i_list);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700219 list_del(&watch->h_list);
Robert Love0eeca282005-07-12 17:06:03 -0400220
Nick Pigginc32ccd82006-03-25 03:07:09 -0800221 if (!inotify_inode_watched(watch->inode))
222 set_dentry_child_flags(watch->inode, 0);
223
Amy Griffis2d9048e2006-06-01 13:10:59 -0700224 idr_remove(&ih->idr, watch->wd);
Robert Love0eeca282005-07-12 17:06:03 -0400225}
226
Amy Griffis3ca10062006-06-01 13:11:05 -0700227/**
228 * inotify_remove_watch_locked - Remove a watch from both the handle and the
229 * inode. Sends the IN_IGNORED event signifying that the inode is no longer
230 * watched. May be invoked from a caller's event handler.
231 * @ih: inotify handle associated with watch
232 * @watch: watch to remove
Robert Love0eeca282005-07-12 17:06:03 -0400233 *
Amy Griffis2d9048e2006-06-01 13:10:59 -0700234 * Callers must hold both inode->inotify_mutex and ih->mutex.
Robert Love0eeca282005-07-12 17:06:03 -0400235 */
Amy Griffis3ca10062006-06-01 13:11:05 -0700236void inotify_remove_watch_locked(struct inotify_handle *ih,
237 struct inotify_watch *watch)
Robert Love0eeca282005-07-12 17:06:03 -0400238{
Amy Griffis2d9048e2006-06-01 13:10:59 -0700239 remove_watch_no_event(watch, ih);
Amy Griffis7c297722006-06-01 13:11:01 -0700240 ih->in_ops->handle_event(watch, watch->wd, IN_IGNORED, 0, NULL, NULL);
Robert Love0eeca282005-07-12 17:06:03 -0400241}
Amy Griffis3ca10062006-06-01 13:11:05 -0700242EXPORT_SYMBOL_GPL(inotify_remove_watch_locked);
Robert Love0eeca282005-07-12 17:06:03 -0400243
Amy Griffis2d9048e2006-06-01 13:10:59 -0700244/* Kernel API for producing events */
Nick Pigginc32ccd82006-03-25 03:07:09 -0800245
Robert Love0eeca282005-07-12 17:06:03 -0400246/*
Nick Pigginc32ccd82006-03-25 03:07:09 -0800247 * inotify_d_instantiate - instantiate dcache entry for inode
Robert Love0eeca282005-07-12 17:06:03 -0400248 */
Nick Pigginc32ccd82006-03-25 03:07:09 -0800249void inotify_d_instantiate(struct dentry *entry, struct inode *inode)
Robert Love0eeca282005-07-12 17:06:03 -0400250{
Nick Pigginc32ccd82006-03-25 03:07:09 -0800251 struct dentry *parent;
252
253 if (!inode)
254 return;
255
256 WARN_ON(entry->d_flags & DCACHE_INOTIFY_PARENT_WATCHED);
257 spin_lock(&entry->d_lock);
258 parent = entry->d_parent;
Arnd Bergmann091e8812006-04-10 22:54:31 -0700259 if (parent->d_inode && inotify_inode_watched(parent->d_inode))
Nick Pigginc32ccd82006-03-25 03:07:09 -0800260 entry->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
261 spin_unlock(&entry->d_lock);
Robert Love0eeca282005-07-12 17:06:03 -0400262}
263
Nick Pigginc32ccd82006-03-25 03:07:09 -0800264/*
265 * inotify_d_move - dcache entry has been moved
266 */
267void inotify_d_move(struct dentry *entry)
268{
269 struct dentry *parent;
270
271 parent = entry->d_parent;
272 if (inotify_inode_watched(parent->d_inode))
273 entry->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
274 else
275 entry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED;
276}
Robert Love0eeca282005-07-12 17:06:03 -0400277
278/**
279 * inotify_inode_queue_event - queue an event to all watches on this inode
280 * @inode: inode event is originating from
281 * @mask: event mask describing this event
282 * @cookie: cookie for synchronization, or zero
283 * @name: filename, if any
Amy Griffis7c297722006-06-01 13:11:01 -0700284 * @n_inode: inode associated with name
Robert Love0eeca282005-07-12 17:06:03 -0400285 */
286void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie,
Amy Griffis7c297722006-06-01 13:11:01 -0700287 const char *name, struct inode *n_inode)
Robert Love0eeca282005-07-12 17:06:03 -0400288{
289 struct inotify_watch *watch, *next;
290
291 if (!inotify_inode_watched(inode))
292 return;
293
Ingo Molnard4f9af92006-03-23 03:00:30 -0800294 mutex_lock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400295 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
296 u32 watch_mask = watch->mask;
297 if (watch_mask & mask) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700298 struct inotify_handle *ih= watch->ih;
299 mutex_lock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400300 if (watch_mask & IN_ONESHOT)
Amy Griffis2d9048e2006-06-01 13:10:59 -0700301 remove_watch_no_event(watch, ih);
Amy Griffis7c297722006-06-01 13:11:01 -0700302 ih->in_ops->handle_event(watch, watch->wd, mask, cookie,
303 name, n_inode);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700304 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400305 }
306 }
Ingo Molnard4f9af92006-03-23 03:00:30 -0800307 mutex_unlock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400308}
309EXPORT_SYMBOL_GPL(inotify_inode_queue_event);
310
311/**
312 * inotify_dentry_parent_queue_event - queue an event to a dentry's parent
313 * @dentry: the dentry in question, we queue against this dentry's parent
314 * @mask: event mask describing this event
315 * @cookie: cookie for synchronization, or zero
316 * @name: filename, if any
317 */
318void inotify_dentry_parent_queue_event(struct dentry *dentry, u32 mask,
319 u32 cookie, const char *name)
320{
321 struct dentry *parent;
322 struct inode *inode;
323
Nick Pigginc32ccd82006-03-25 03:07:09 -0800324 if (!(dentry->d_flags & DCACHE_INOTIFY_PARENT_WATCHED))
John McCutchan820249b2005-09-06 15:16:38 -0700325 return;
326
Robert Love0eeca282005-07-12 17:06:03 -0400327 spin_lock(&dentry->d_lock);
328 parent = dentry->d_parent;
329 inode = parent->d_inode;
330
331 if (inotify_inode_watched(inode)) {
332 dget(parent);
333 spin_unlock(&dentry->d_lock);
Amy Griffis7c297722006-06-01 13:11:01 -0700334 inotify_inode_queue_event(inode, mask, cookie, name,
335 dentry->d_inode);
Robert Love0eeca282005-07-12 17:06:03 -0400336 dput(parent);
337 } else
338 spin_unlock(&dentry->d_lock);
339}
340EXPORT_SYMBOL_GPL(inotify_dentry_parent_queue_event);
341
342/**
343 * inotify_get_cookie - return a unique cookie for use in synchronizing events.
344 */
345u32 inotify_get_cookie(void)
346{
347 return atomic_inc_return(&inotify_cookie);
348}
349EXPORT_SYMBOL_GPL(inotify_get_cookie);
350
351/**
352 * inotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
353 * @list: list of inodes being unmounted (sb->s_inodes)
354 *
355 * Called with inode_lock held, protecting the unmounting super block's list
Ingo Molnarf24075b2006-03-23 03:00:34 -0800356 * of inodes, and with iprune_mutex held, keeping shrink_icache_memory() at bay.
Robert Love0eeca282005-07-12 17:06:03 -0400357 * We temporarily drop inode_lock, however, and CAN block.
358 */
359void inotify_unmount_inodes(struct list_head *list)
360{
361 struct inode *inode, *next_i, *need_iput = NULL;
362
363 list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
364 struct inotify_watch *watch, *next_w;
365 struct inode *need_iput_tmp;
366 struct list_head *watches;
367
368 /*
369 * If i_count is zero, the inode cannot have any watches and
370 * doing an __iget/iput with MS_ACTIVE clear would actually
371 * evict all inodes with zero i_count from icache which is
372 * unnecessarily violent and may in fact be illegal to do.
373 */
374 if (!atomic_read(&inode->i_count))
375 continue;
376
377 /*
378 * We cannot __iget() an inode in state I_CLEAR, I_FREEING, or
379 * I_WILL_FREE which is fine because by that point the inode
380 * cannot have any associated watches.
381 */
382 if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))
383 continue;
384
385 need_iput_tmp = need_iput;
386 need_iput = NULL;
Amy Griffis3ca10062006-06-01 13:11:05 -0700387 /* In case inotify_remove_watch_locked() drops a reference. */
Robert Love0eeca282005-07-12 17:06:03 -0400388 if (inode != need_iput_tmp)
389 __iget(inode);
390 else
391 need_iput_tmp = NULL;
392 /* In case the dropping of a reference would nuke next_i. */
393 if ((&next_i->i_sb_list != list) &&
394 atomic_read(&next_i->i_count) &&
395 !(next_i->i_state & (I_CLEAR | I_FREEING |
396 I_WILL_FREE))) {
397 __iget(next_i);
398 need_iput = next_i;
399 }
400
401 /*
402 * We can safely drop inode_lock here because we hold
403 * references on both inode and next_i. Also no new inodes
404 * will be added since the umount has begun. Finally,
Ingo Molnarf24075b2006-03-23 03:00:34 -0800405 * iprune_mutex keeps shrink_icache_memory() away.
Robert Love0eeca282005-07-12 17:06:03 -0400406 */
407 spin_unlock(&inode_lock);
408
409 if (need_iput_tmp)
410 iput(need_iput_tmp);
411
412 /* for each watch, send IN_UNMOUNT and then remove it */
Ingo Molnard4f9af92006-03-23 03:00:30 -0800413 mutex_lock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400414 watches = &inode->inotify_watches;
415 list_for_each_entry_safe(watch, next_w, watches, i_list) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700416 struct inotify_handle *ih= watch->ih;
417 mutex_lock(&ih->mutex);
418 ih->in_ops->handle_event(watch, watch->wd, IN_UNMOUNT, 0,
Amy Griffis7c297722006-06-01 13:11:01 -0700419 NULL, NULL);
Amy Griffis3ca10062006-06-01 13:11:05 -0700420 inotify_remove_watch_locked(ih, watch);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700421 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400422 }
Ingo Molnard4f9af92006-03-23 03:00:30 -0800423 mutex_unlock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400424 iput(inode);
425
426 spin_lock(&inode_lock);
427 }
428}
429EXPORT_SYMBOL_GPL(inotify_unmount_inodes);
430
431/**
432 * inotify_inode_is_dead - an inode has been deleted, cleanup any watches
433 * @inode: inode that is about to be removed
434 */
435void inotify_inode_is_dead(struct inode *inode)
436{
437 struct inotify_watch *watch, *next;
438
Ingo Molnard4f9af92006-03-23 03:00:30 -0800439 mutex_lock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400440 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700441 struct inotify_handle *ih = watch->ih;
442 mutex_lock(&ih->mutex);
Amy Griffis3ca10062006-06-01 13:11:05 -0700443 inotify_remove_watch_locked(ih, watch);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700444 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400445 }
Ingo Molnard4f9af92006-03-23 03:00:30 -0800446 mutex_unlock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400447}
448EXPORT_SYMBOL_GPL(inotify_inode_is_dead);
449
Amy Griffis2d9048e2006-06-01 13:10:59 -0700450/* Kernel Consumer API */
Robert Love0eeca282005-07-12 17:06:03 -0400451
Amy Griffis2d9048e2006-06-01 13:10:59 -0700452/**
453 * inotify_init - allocate and initialize an inotify instance
454 * @ops: caller's inotify operations
455 */
456struct inotify_handle *inotify_init(const struct inotify_operations *ops)
Robert Love0eeca282005-07-12 17:06:03 -0400457{
Amy Griffis2d9048e2006-06-01 13:10:59 -0700458 struct inotify_handle *ih;
Robert Love0eeca282005-07-12 17:06:03 -0400459
Amy Griffis2d9048e2006-06-01 13:10:59 -0700460 ih = kmalloc(sizeof(struct inotify_handle), GFP_KERNEL);
461 if (unlikely(!ih))
462 return ERR_PTR(-ENOMEM);
Robert Love0eeca282005-07-12 17:06:03 -0400463
Amy Griffis2d9048e2006-06-01 13:10:59 -0700464 idr_init(&ih->idr);
465 INIT_LIST_HEAD(&ih->watches);
466 mutex_init(&ih->mutex);
467 ih->last_wd = 0;
468 ih->in_ops = ops;
469 atomic_set(&ih->count, 0);
470 get_inotify_handle(ih);
471
472 return ih;
Robert Love0eeca282005-07-12 17:06:03 -0400473}
Amy Griffis2d9048e2006-06-01 13:10:59 -0700474EXPORT_SYMBOL_GPL(inotify_init);
Robert Love0eeca282005-07-12 17:06:03 -0400475
Amy Griffis2d9048e2006-06-01 13:10:59 -0700476/**
Amy Griffisa9dc9712006-06-01 13:11:03 -0700477 * inotify_init_watch - initialize an inotify watch
478 * @watch: watch to initialize
479 */
480void inotify_init_watch(struct inotify_watch *watch)
481{
482 INIT_LIST_HEAD(&watch->h_list);
483 INIT_LIST_HEAD(&watch->i_list);
484 atomic_set(&watch->count, 0);
485 get_inotify_watch(watch); /* initial get */
486}
487EXPORT_SYMBOL_GPL(inotify_init_watch);
488
489/**
Amy Griffis2d9048e2006-06-01 13:10:59 -0700490 * inotify_destroy - clean up and destroy an inotify instance
491 * @ih: inotify handle
492 */
493void inotify_destroy(struct inotify_handle *ih)
Robert Love0eeca282005-07-12 17:06:03 -0400494{
Robert Love0eeca282005-07-12 17:06:03 -0400495 /*
Amy Griffis2d9048e2006-06-01 13:10:59 -0700496 * Destroy all of the watches for this handle. Unfortunately, not very
Robert Love0eeca282005-07-12 17:06:03 -0400497 * pretty. We cannot do a simple iteration over the list, because we
498 * do not know the inode until we iterate to the watch. But we need to
Amy Griffis2d9048e2006-06-01 13:10:59 -0700499 * hold inode->inotify_mutex before ih->mutex. The following works.
Robert Love0eeca282005-07-12 17:06:03 -0400500 */
501 while (1) {
502 struct inotify_watch *watch;
503 struct list_head *watches;
504 struct inode *inode;
505
Amy Griffis2d9048e2006-06-01 13:10:59 -0700506 mutex_lock(&ih->mutex);
507 watches = &ih->watches;
Robert Love0eeca282005-07-12 17:06:03 -0400508 if (list_empty(watches)) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700509 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400510 break;
511 }
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700512 watch = list_first_entry(watches, struct inotify_watch, h_list);
Robert Love0eeca282005-07-12 17:06:03 -0400513 get_inotify_watch(watch);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700514 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400515
516 inode = watch->inode;
Ingo Molnard4f9af92006-03-23 03:00:30 -0800517 mutex_lock(&inode->inotify_mutex);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700518 mutex_lock(&ih->mutex);
Amy Griffis66055a42006-05-20 15:00:06 -0700519
520 /* make sure we didn't race with another list removal */
Amy Griffis2d9048e2006-06-01 13:10:59 -0700521 if (likely(idr_find(&ih->idr, watch->wd))) {
522 remove_watch_no_event(watch, ih);
523 put_inotify_watch(watch);
524 }
Amy Griffis66055a42006-05-20 15:00:06 -0700525
Amy Griffis2d9048e2006-06-01 13:10:59 -0700526 mutex_unlock(&ih->mutex);
Ingo Molnard4f9af92006-03-23 03:00:30 -0800527 mutex_unlock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400528 put_inotify_watch(watch);
529 }
530
Amy Griffis2d9048e2006-06-01 13:10:59 -0700531 /* free this handle: the put matching the get in inotify_init() */
532 put_inotify_handle(ih);
Robert Love0eeca282005-07-12 17:06:03 -0400533}
Amy Griffis2d9048e2006-06-01 13:10:59 -0700534EXPORT_SYMBOL_GPL(inotify_destroy);
Robert Love0eeca282005-07-12 17:06:03 -0400535
Amy Griffis2d9048e2006-06-01 13:10:59 -0700536/**
Amy Griffisa9dc9712006-06-01 13:11:03 -0700537 * inotify_find_watch - find an existing watch for an (ih,inode) pair
538 * @ih: inotify handle
539 * @inode: inode to watch
540 * @watchp: pointer to existing inotify_watch
541 *
542 * Caller must pin given inode (via nameidata).
543 */
544s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode,
545 struct inotify_watch **watchp)
546{
547 struct inotify_watch *old;
548 int ret = -ENOENT;
549
550 mutex_lock(&inode->inotify_mutex);
551 mutex_lock(&ih->mutex);
552
553 old = inode_find_handle(inode, ih);
554 if (unlikely(old)) {
555 get_inotify_watch(old); /* caller must put watch */
556 *watchp = old;
557 ret = old->wd;
558 }
559
560 mutex_unlock(&ih->mutex);
561 mutex_unlock(&inode->inotify_mutex);
562
563 return ret;
564}
565EXPORT_SYMBOL_GPL(inotify_find_watch);
566
567/**
Amy Griffis2d9048e2006-06-01 13:10:59 -0700568 * inotify_find_update_watch - find and update the mask of an existing watch
569 * @ih: inotify handle
570 * @inode: inode's watch to update
571 * @mask: mask of events to watch
572 *
573 * Caller must pin given inode (via nameidata).
574 */
575s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode,
576 u32 mask)
577{
578 struct inotify_watch *old;
579 int mask_add = 0;
580 int ret;
581
582 if (mask & IN_MASK_ADD)
583 mask_add = 1;
584
585 /* don't allow invalid bits: we don't want flags set */
586 mask &= IN_ALL_EVENTS | IN_ONESHOT;
587 if (unlikely(!mask))
588 return -EINVAL;
589
590 mutex_lock(&inode->inotify_mutex);
591 mutex_lock(&ih->mutex);
592
593 /*
594 * Handle the case of re-adding a watch on an (inode,ih) pair that we
595 * are already watching. We just update the mask and return its wd.
596 */
597 old = inode_find_handle(inode, ih);
598 if (unlikely(!old)) {
599 ret = -ENOENT;
600 goto out;
601 }
602
603 if (mask_add)
604 old->mask |= mask;
605 else
606 old->mask = mask;
607 ret = old->wd;
608out:
609 mutex_unlock(&ih->mutex);
610 mutex_unlock(&inode->inotify_mutex);
611 return ret;
612}
613EXPORT_SYMBOL_GPL(inotify_find_update_watch);
614
615/**
616 * inotify_add_watch - add a watch to an inotify instance
617 * @ih: inotify handle
618 * @watch: caller allocated watch structure
619 * @inode: inode to watch
620 * @mask: mask of events to watch
621 *
622 * Caller must pin given inode (via nameidata).
623 * Caller must ensure it only calls inotify_add_watch() once per watch.
624 * Calls inotify_handle_get_wd() so may sleep.
625 */
626s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch,
627 struct inode *inode, u32 mask)
628{
629 int ret = 0;
630
631 /* don't allow invalid bits: we don't want flags set */
632 mask &= IN_ALL_EVENTS | IN_ONESHOT;
633 if (unlikely(!mask))
634 return -EINVAL;
635 watch->mask = mask;
636
637 mutex_lock(&inode->inotify_mutex);
638 mutex_lock(&ih->mutex);
639
640 /* Initialize a new watch */
641 ret = inotify_handle_get_wd(ih, watch);
642 if (unlikely(ret))
643 goto out;
644 ret = watch->wd;
645
Amy Griffis2d9048e2006-06-01 13:10:59 -0700646 /* save a reference to handle and bump the count to make it official */
647 get_inotify_handle(ih);
648 watch->ih = ih;
649
650 /*
651 * Save a reference to the inode and bump the ref count to make it
652 * official. We hold a reference to nameidata, which makes this safe.
653 */
654 watch->inode = igrab(inode);
655
Amy Griffis2d9048e2006-06-01 13:10:59 -0700656 if (!inotify_inode_watched(inode))
657 set_dentry_child_flags(inode, 1);
658
659 /* Add the watch to the handle's and the inode's list */
660 list_add(&watch->h_list, &ih->watches);
661 list_add(&watch->i_list, &inode->inotify_watches);
662out:
663 mutex_unlock(&ih->mutex);
664 mutex_unlock(&inode->inotify_mutex);
665 return ret;
666}
667EXPORT_SYMBOL_GPL(inotify_add_watch);
668
669/**
670 * inotify_rm_wd - remove a watch from an inotify instance
671 * @ih: inotify handle
672 * @wd: watch descriptor to remove
Robert Love0eeca282005-07-12 17:06:03 -0400673 *
674 * Can sleep.
675 */
Amy Griffis2d9048e2006-06-01 13:10:59 -0700676int inotify_rm_wd(struct inotify_handle *ih, u32 wd)
Robert Love0eeca282005-07-12 17:06:03 -0400677{
678 struct inotify_watch *watch;
679 struct inode *inode;
680
Amy Griffis2d9048e2006-06-01 13:10:59 -0700681 mutex_lock(&ih->mutex);
682 watch = idr_find(&ih->idr, wd);
Robert Love0eeca282005-07-12 17:06:03 -0400683 if (unlikely(!watch)) {
Amy Griffis2d9048e2006-06-01 13:10:59 -0700684 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400685 return -EINVAL;
686 }
687 get_inotify_watch(watch);
688 inode = watch->inode;
Amy Griffis2d9048e2006-06-01 13:10:59 -0700689 mutex_unlock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400690
Ingo Molnard4f9af92006-03-23 03:00:30 -0800691 mutex_lock(&inode->inotify_mutex);
Amy Griffis2d9048e2006-06-01 13:10:59 -0700692 mutex_lock(&ih->mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400693
694 /* make sure that we did not race */
Amy Griffis2d9048e2006-06-01 13:10:59 -0700695 if (likely(idr_find(&ih->idr, wd) == watch))
Amy Griffis3ca10062006-06-01 13:11:05 -0700696 inotify_remove_watch_locked(ih, watch);
Robert Love0eeca282005-07-12 17:06:03 -0400697
Amy Griffis2d9048e2006-06-01 13:10:59 -0700698 mutex_unlock(&ih->mutex);
Ingo Molnard4f9af92006-03-23 03:00:30 -0800699 mutex_unlock(&inode->inotify_mutex);
Robert Love0eeca282005-07-12 17:06:03 -0400700 put_inotify_watch(watch);
701
702 return 0;
703}
Amy Griffis2d9048e2006-06-01 13:10:59 -0700704EXPORT_SYMBOL_GPL(inotify_rm_wd);
Robert Love0eeca282005-07-12 17:06:03 -0400705
Amy Griffisa9dc9712006-06-01 13:11:03 -0700706/**
707 * inotify_rm_watch - remove a watch from an inotify instance
708 * @ih: inotify handle
709 * @watch: watch to remove
710 *
711 * Can sleep.
712 */
713int inotify_rm_watch(struct inotify_handle *ih,
714 struct inotify_watch *watch)
715{
716 return inotify_rm_wd(ih, watch->wd);
717}
718EXPORT_SYMBOL_GPL(inotify_rm_watch);
719
Robert Love0eeca282005-07-12 17:06:03 -0400720/*
Amy Griffis2d9048e2006-06-01 13:10:59 -0700721 * inotify_setup - core initialization function
Robert Love0eeca282005-07-12 17:06:03 -0400722 */
Robert Loveb6807162005-07-25 15:07:13 -0400723static int __init inotify_setup(void)
Robert Love0eeca282005-07-12 17:06:03 -0400724{
Robert Love0eeca282005-07-12 17:06:03 -0400725 atomic_set(&inotify_cookie, 0);
726
Robert Love0eeca282005-07-12 17:06:03 -0400727 return 0;
728}
729
Robert Loveb6807162005-07-25 15:07:13 -0400730module_init(inotify_setup);