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authorAmy Griffis <amy.griffis@hp.com>2006-06-01 16:10:59 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2006-06-20 05:25:17 -0400
commit2d9048e201bfb67ba21f05e647b1286b8a4a5667 (patch)
tree1df2ca6780d403f3209cf445f8b0b27f45098434 /fs/inotify.c
parent90204e0b7b51e9f2a6905adca12dc331128602c7 (diff)
[PATCH] inotify (1/5): split kernel API from userspace support
The following series of patches introduces a kernel API for inotify, making it possible for kernel modules to benefit from inotify's mechanism for watching inodes. With these patches, inotify will maintain for each caller a list of watches (via an embedded struct inotify_watch), where each inotify_watch is associated with a corresponding struct inode. The caller registers an event handler and specifies for which filesystem events their event handler should be called per inotify_watch. Signed-off-by: Amy Griffis <amy.griffis@hp.com> Acked-by: Robert Love <rml@novell.com> Acked-by: John McCutchan <john@johnmccutchan.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/inotify.c')
-rw-r--r--fs/inotify.c941
1 files changed, 230 insertions, 711 deletions
diff --git a/fs/inotify.c b/fs/inotify.c
index 732ec4bd5774..a1bedf3975ca 100644
--- a/fs/inotify.c
+++ b/fs/inotify.c
@@ -5,7 +5,10 @@
5 * John McCutchan <ttb@tentacle.dhs.org> 5 * John McCutchan <ttb@tentacle.dhs.org>
6 * Robert Love <rml@novell.com> 6 * Robert Love <rml@novell.com>
7 * 7 *
8 * Kernel API added by: Amy Griffis <amy.griffis@hp.com>
9 *
8 * Copyright (C) 2005 John McCutchan 10 * Copyright (C) 2005 John McCutchan
11 * Copyright 2006 Hewlett-Packard Development Company, L.P.
9 * 12 *
10 * This program is free software; you can redistribute it and/or modify it 13 * 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 14 * under the terms of the GNU General Public License as published by the
@@ -20,35 +23,17 @@
20 23
21#include <linux/module.h> 24#include <linux/module.h>
22#include <linux/kernel.h> 25#include <linux/kernel.h>
23#include <linux/sched.h>
24#include <linux/spinlock.h> 26#include <linux/spinlock.h>
25#include <linux/idr.h> 27#include <linux/idr.h>
26#include <linux/slab.h> 28#include <linux/slab.h>
27#include <linux/fs.h> 29#include <linux/fs.h>
28#include <linux/file.h>
29#include <linux/mount.h>
30#include <linux/namei.h>
31#include <linux/poll.h>
32#include <linux/init.h> 30#include <linux/init.h>
33#include <linux/list.h> 31#include <linux/list.h>
34#include <linux/writeback.h> 32#include <linux/writeback.h>
35#include <linux/inotify.h> 33#include <linux/inotify.h>
36#include <linux/syscalls.h>
37
38#include <asm/ioctls.h>
39 34
40static atomic_t inotify_cookie; 35static atomic_t inotify_cookie;
41 36
42static kmem_cache_t *watch_cachep __read_mostly;
43static kmem_cache_t *event_cachep __read_mostly;
44
45static struct vfsmount *inotify_mnt __read_mostly;
46
47/* these are configurable via /proc/sys/fs/inotify/ */
48int inotify_max_user_instances __read_mostly;
49int inotify_max_user_watches __read_mostly;
50int inotify_max_queued_events __read_mostly;
51
52/* 37/*
53 * Lock ordering: 38 * Lock ordering:
54 * 39 *
@@ -56,327 +41,108 @@ int inotify_max_queued_events __read_mostly;
56 * iprune_mutex (synchronize shrink_icache_memory()) 41 * iprune_mutex (synchronize shrink_icache_memory())
57 * inode_lock (protects the super_block->s_inodes list) 42 * inode_lock (protects the super_block->s_inodes list)
58 * inode->inotify_mutex (protects inode->inotify_watches and watches->i_list) 43 * inode->inotify_mutex (protects inode->inotify_watches and watches->i_list)
59 * inotify_dev->mutex (protects inotify_device and watches->d_list) 44 * inotify_handle->mutex (protects inotify_handle and watches->h_list)
45 *
46 * The inode->inotify_mutex and inotify_handle->mutex and held during execution
47 * of a caller's event handler. Thus, the caller must not hold any locks
48 * taken in their event handler while calling any of the published inotify
49 * interfaces.
60 */ 50 */
61 51
62/* 52/*
63 * Lifetimes of the three main data structures--inotify_device, inode, and 53 * Lifetimes of the three main data structures--inotify_handle, inode, and
64 * inotify_watch--are managed by reference count. 54 * inotify_watch--are managed by reference count.
65 * 55 *
66 * inotify_device: Lifetime is from inotify_init() until release. Additional 56 * inotify_handle: Lifetime is from inotify_init() to inotify_destroy().
67 * references can bump the count via get_inotify_dev() and drop the count via 57 * Additional references can bump the count via get_inotify_handle() and drop
68 * put_inotify_dev(). 58 * the count via put_inotify_handle().
69 * 59 *
70 * inotify_watch: Lifetime is from create_watch() to destory_watch(). 60 * inotify_watch: for inotify's purposes, lifetime is from inotify_add_watch()
71 * Additional references can bump the count via get_inotify_watch() and drop 61 * to remove_watch_no_event(). Additional references can bump the count via
72 * the count via put_inotify_watch(). 62 * get_inotify_watch() and drop the count via put_inotify_watch(). The caller
63 * is reponsible for the final put after receiving IN_IGNORED, or when using
64 * IN_ONESHOT after receiving the first event. Inotify does the final put if
65 * inotify_destroy() is called.
73 * 66 *
74 * inode: Pinned so long as the inode is associated with a watch, from 67 * inode: Pinned so long as the inode is associated with a watch, from
75 * create_watch() to put_inotify_watch(). 68 * inotify_add_watch() to the final put_inotify_watch().
76 */ 69 */
77 70
78/* 71/*
79 * struct inotify_device - represents an inotify instance 72 * struct inotify_handle - represents an inotify instance
80 * 73 *
81 * This structure is protected by the mutex 'mutex'. 74 * This structure is protected by the mutex 'mutex'.
82 */ 75 */
83struct inotify_device { 76struct inotify_handle {
84 wait_queue_head_t wq; /* wait queue for i/o */
85 struct idr idr; /* idr mapping wd -> watch */ 77 struct idr idr; /* idr mapping wd -> watch */
86 struct mutex mutex; /* protects this bad boy */ 78 struct mutex mutex; /* protects this bad boy */
87 struct list_head events; /* list of queued events */
88 struct list_head watches; /* list of watches */ 79 struct list_head watches; /* list of watches */
89 atomic_t count; /* reference count */ 80 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 */
94 u32 last_wd; /* the last wd allocated */ 81 u32 last_wd; /* the last wd allocated */
82 const struct inotify_operations *in_ops; /* inotify caller operations */
95}; 83};
96 84
97/* 85static inline void get_inotify_handle(struct inotify_handle *ih)
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->mutex of the device in which we are queued.
104 */
105struct 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->mutex of the associated watch->dev.
115 * i_list and mask are protected by inode->inotify_mutex of the associated inode.
116 * dev, inode, and wd are never written to once the watch is created.
117 */
118struct 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
128#ifdef CONFIG_SYSCTL
129
130#include <linux/sysctl.h>
131
132static int zero;
133
134ctl_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
169static inline void get_inotify_dev(struct inotify_device *dev)
170{ 86{
171 atomic_inc(&dev->count); 87 atomic_inc(&ih->count);
172} 88}
173 89
174static inline void put_inotify_dev(struct inotify_device *dev) 90static inline void put_inotify_handle(struct inotify_handle *ih)
175{ 91{
176 if (atomic_dec_and_test(&dev->count)) { 92 if (atomic_dec_and_test(&ih->count)) {
177 atomic_dec(&dev->user->inotify_devs); 93 idr_destroy(&ih->idr);
178 free_uid(dev->user); 94 kfree(ih);
179 idr_destroy(&dev->idr);
180 kfree(dev);
181 } 95 }
182} 96}
183 97
184static inline void get_inotify_watch(struct inotify_watch *watch) 98/**
99 * get_inotify_watch - grab a reference to an inotify_watch
100 * @watch: watch to grab
101 */
102void get_inotify_watch(struct inotify_watch *watch)
185{ 103{
186 atomic_inc(&watch->count); 104 atomic_inc(&watch->count);
187} 105}
106EXPORT_SYMBOL_GPL(get_inotify_watch);
188 107
189/* 108/**
190 * put_inotify_watch - decrements the ref count on a given watch. cleans up 109 * put_inotify_watch - decrements the ref count on a given watch. cleans up
191 * the watch and its references if the count reaches zero. 110 * watch references if the count reaches zero. inotify_watch is freed by
111 * inotify callers via the destroy_watch() op.
112 * @watch: watch to release
192 */ 113 */
193static inline void put_inotify_watch(struct inotify_watch *watch) 114void put_inotify_watch(struct inotify_watch *watch)
194{ 115{
195 if (atomic_dec_and_test(&watch->count)) { 116 if (atomic_dec_and_test(&watch->count)) {
196 put_inotify_dev(watch->dev); 117 struct inotify_handle *ih = watch->ih;
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 */
207static 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->mutex.
264 */
265static inline struct inotify_kernel_event *
266inotify_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->mutex. Can sleep (calls kernel_event()).
275 */
276static 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->mutex.
318 */
319static void remove_kevent(struct inotify_device *dev,
320 struct inotify_kernel_event *kevent)
321{
322 list_del(&kevent->list);
323 118
324 dev->event_count--; 119 iput(watch->inode);
325 dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len; 120 ih->in_ops->destroy_watch(watch);
326 121 put_inotify_handle(ih);
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->mutex.
335 */
336static 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 } 122 }
343} 123}
124EXPORT_SYMBOL_GPL(put_inotify_watch);
344 125
345/* 126/*
346 * inotify_dev_get_wd - returns the next WD for use by the given dev 127 * inotify_handle_get_wd - returns the next WD for use by the given handle
347 * 128 *
348 * Callers must hold dev->mutex. This function can sleep. 129 * Callers must hold ih->mutex. This function can sleep.
349 */ 130 */
350static int inotify_dev_get_wd(struct inotify_device *dev, 131static int inotify_handle_get_wd(struct inotify_handle *ih,
351 struct inotify_watch *watch) 132 struct inotify_watch *watch)
352{ 133{
353 int ret; 134 int ret;
354 135
355 do { 136 do {
356 if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL))) 137 if (unlikely(!idr_pre_get(&ih->idr, GFP_KERNEL)))
357 return -ENOSPC; 138 return -ENOSPC;
358 ret = idr_get_new_above(&dev->idr, watch, dev->last_wd+1, &watch->wd); 139 ret = idr_get_new_above(&ih->idr, watch, ih->last_wd+1, &watch->wd);
359 } while (ret == -EAGAIN); 140 } while (ret == -EAGAIN);
360 141
361 return ret; 142 if (likely(!ret))
362} 143 ih->last_wd = watch->wd;
363 144
364/* 145 return ret;
365 * find_inode - resolve a user-given path to a specific inode and return a nd
366 */
367static int find_inode(const char __user *dirname, struct nameidata *nd,
368 unsigned flags)
369{
370 int error;
371
372 error = __user_walk(dirname, flags, nd);
373 if (error)
374 return error;
375 /* you can only watch an inode if you have read permissions on it */
376 error = vfs_permission(nd, MAY_READ);
377 if (error)
378 path_release(nd);
379 return error;
380} 146}
381 147
382/* 148/*
@@ -422,67 +188,18 @@ static void set_dentry_child_flags(struct inode *inode, int watched)
422} 188}
423 189
424/* 190/*
425 * create_watch - creates a watch on the given device. 191 * inotify_find_handle - find the watch associated with the given inode and
426 * 192 * handle
427 * Callers must hold dev->mutex. Calls inotify_dev_get_wd() so may sleep.
428 * Both 'dev' and 'inode' (by way of nameidata) need to be pinned.
429 */
430static struct inotify_watch *create_watch(struct inotify_device *dev,
431 u32 mask, struct inode *inode)
432{
433 struct inotify_watch *watch;
434 int ret;
435
436 if (atomic_read(&dev->user->inotify_watches) >=
437 inotify_max_user_watches)
438 return ERR_PTR(-ENOSPC);
439
440 watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL);
441 if (unlikely(!watch))
442 return ERR_PTR(-ENOMEM);
443
444 ret = inotify_dev_get_wd(dev, watch);
445 if (unlikely(ret)) {
446 kmem_cache_free(watch_cachep, watch);
447 return ERR_PTR(ret);
448 }
449
450 dev->last_wd = watch->wd;
451 watch->mask = mask;
452 atomic_set(&watch->count, 0);
453 INIT_LIST_HEAD(&watch->d_list);
454 INIT_LIST_HEAD(&watch->i_list);
455
456 /* save a reference to device and bump the count to make it official */
457 get_inotify_dev(dev);
458 watch->dev = dev;
459
460 /*
461 * Save a reference to the inode and bump the ref count to make it
462 * official. We hold a reference to nameidata, which makes this safe.
463 */
464 watch->inode = igrab(inode);
465
466 /* bump our own count, corresponding to our entry in dev->watches */
467 get_inotify_watch(watch);
468
469 atomic_inc(&dev->user->inotify_watches);
470
471 return watch;
472}
473
474/*
475 * inotify_find_dev - find the watch associated with the given inode and dev
476 * 193 *
477 * Callers must hold inode->inotify_mutex. 194 * Callers must hold inode->inotify_mutex.
478 */ 195 */
479static struct inotify_watch *inode_find_dev(struct inode *inode, 196static struct inotify_watch *inode_find_handle(struct inode *inode,
480 struct inotify_device *dev) 197 struct inotify_handle *ih)
481{ 198{
482 struct inotify_watch *watch; 199 struct inotify_watch *watch;
483 200
484 list_for_each_entry(watch, &inode->inotify_watches, i_list) { 201 list_for_each_entry(watch, &inode->inotify_watches, i_list) {
485 if (watch->dev == dev) 202 if (watch->ih == ih)
486 return watch; 203 return watch;
487 } 204 }
488 205
@@ -491,39 +208,34 @@ static struct inotify_watch *inode_find_dev(struct inode *inode,
491 208
492/* 209/*
493 * remove_watch_no_event - remove_watch() without the IN_IGNORED event. 210 * remove_watch_no_event - remove_watch() without the IN_IGNORED event.
211 *
212 * Callers must hold both inode->inotify_mutex and ih->mutex.
494 */ 213 */
495static void remove_watch_no_event(struct inotify_watch *watch, 214static void remove_watch_no_event(struct inotify_watch *watch,
496 struct inotify_device *dev) 215 struct inotify_handle *ih)
497{ 216{
498 list_del(&watch->i_list); 217 list_del(&watch->i_list);
499 list_del(&watch->d_list); 218 list_del(&watch->h_list);
500 219
501 if (!inotify_inode_watched(watch->inode)) 220 if (!inotify_inode_watched(watch->inode))
502 set_dentry_child_flags(watch->inode, 0); 221 set_dentry_child_flags(watch->inode, 0);
503 222
504 atomic_dec(&dev->user->inotify_watches); 223 idr_remove(&ih->idr, watch->wd);
505 idr_remove(&dev->idr, watch->wd);
506 put_inotify_watch(watch);
507} 224}
508 225
509/* 226/*
510 * remove_watch - Remove a watch from both the device and the inode. Sends 227 * remove_watch - Remove a watch from both the handle and the inode. Sends
511 * the IN_IGNORED event to the given device signifying that the inode is no 228 * the IN_IGNORED event signifying that the inode is no longer watched.
512 * longer watched.
513 *
514 * Callers must hold both inode->inotify_mutex and dev->mutex. We drop a
515 * reference to the inode before returning.
516 * 229 *
517 * The inode is not iput() so as to remain atomic. If the inode needs to be 230 * Callers must hold both inode->inotify_mutex and ih->mutex.
518 * iput(), the call returns one. Otherwise, it returns zero.
519 */ 231 */
520static void remove_watch(struct inotify_watch *watch,struct inotify_device *dev) 232static void remove_watch(struct inotify_watch *watch, struct inotify_handle *ih)
521{ 233{
522 inotify_dev_queue_event(dev, watch, IN_IGNORED, 0, NULL); 234 remove_watch_no_event(watch, ih);
523 remove_watch_no_event(watch, dev); 235 ih->in_ops->handle_event(watch, watch->wd, IN_IGNORED, 0, NULL);
524} 236}
525 237
526/* Kernel API */ 238/* Kernel API for producing events */
527 239
528/* 240/*
529 * inotify_d_instantiate - instantiate dcache entry for inode 241 * inotify_d_instantiate - instantiate dcache entry for inode
@@ -576,14 +288,12 @@ void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie,
576 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) { 288 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
577 u32 watch_mask = watch->mask; 289 u32 watch_mask = watch->mask;
578 if (watch_mask & mask) { 290 if (watch_mask & mask) {
579 struct inotify_device *dev = watch->dev; 291 struct inotify_handle *ih= watch->ih;
580 get_inotify_watch(watch); 292 mutex_lock(&ih->mutex);
581 mutex_lock(&dev->mutex);
582 inotify_dev_queue_event(dev, watch, mask, cookie, name);
583 if (watch_mask & IN_ONESHOT) 293 if (watch_mask & IN_ONESHOT)
584 remove_watch_no_event(watch, dev); 294 remove_watch_no_event(watch, ih);
585 mutex_unlock(&dev->mutex); 295 ih->in_ops->handle_event(watch, watch->wd, mask, cookie, name);
586 put_inotify_watch(watch); 296 mutex_unlock(&ih->mutex);
587 } 297 }
588 } 298 }
589 mutex_unlock(&inode->inotify_mutex); 299 mutex_unlock(&inode->inotify_mutex);
@@ -694,11 +404,12 @@ void inotify_unmount_inodes(struct list_head *list)
694 mutex_lock(&inode->inotify_mutex); 404 mutex_lock(&inode->inotify_mutex);
695 watches = &inode->inotify_watches; 405 watches = &inode->inotify_watches;
696 list_for_each_entry_safe(watch, next_w, watches, i_list) { 406 list_for_each_entry_safe(watch, next_w, watches, i_list) {
697 struct inotify_device *dev = watch->dev; 407 struct inotify_handle *ih= watch->ih;
698 mutex_lock(&dev->mutex); 408 mutex_lock(&ih->mutex);
699 inotify_dev_queue_event(dev, watch, IN_UNMOUNT,0,NULL); 409 ih->in_ops->handle_event(watch, watch->wd, IN_UNMOUNT, 0,
700 remove_watch(watch, dev); 410 NULL);
701 mutex_unlock(&dev->mutex); 411 remove_watch(watch, ih);
412 mutex_unlock(&ih->mutex);
702 } 413 }
703 mutex_unlock(&inode->inotify_mutex); 414 mutex_unlock(&inode->inotify_mutex);
704 iput(inode); 415 iput(inode);
@@ -718,432 +429,240 @@ void inotify_inode_is_dead(struct inode *inode)
718 429
719 mutex_lock(&inode->inotify_mutex); 430 mutex_lock(&inode->inotify_mutex);
720 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) { 431 list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
721 struct inotify_device *dev = watch->dev; 432 struct inotify_handle *ih = watch->ih;
722 mutex_lock(&dev->mutex); 433 mutex_lock(&ih->mutex);
723 remove_watch(watch, dev); 434 remove_watch(watch, ih);
724 mutex_unlock(&dev->mutex); 435 mutex_unlock(&ih->mutex);
725 } 436 }
726 mutex_unlock(&inode->inotify_mutex); 437 mutex_unlock(&inode->inotify_mutex);
727} 438}
728EXPORT_SYMBOL_GPL(inotify_inode_is_dead); 439EXPORT_SYMBOL_GPL(inotify_inode_is_dead);
729 440
730/* Device Interface */ 441/* Kernel Consumer API */
731
732static unsigned int inotify_poll(struct file *file, poll_table *wait)
733{
734 struct inotify_device *dev = file->private_data;
735 int ret = 0;
736
737 poll_wait(file, &dev->wq, wait);
738 mutex_lock(&dev->mutex);
739 if (!list_empty(&dev->events))
740 ret = POLLIN | POLLRDNORM;
741 mutex_unlock(&dev->mutex);
742
743 return ret;
744}
745 442
746static ssize_t inotify_read(struct file *file, char __user *buf, 443/**
747 size_t count, loff_t *pos) 444 * inotify_init - allocate and initialize an inotify instance
445 * @ops: caller's inotify operations
446 */
447struct inotify_handle *inotify_init(const struct inotify_operations *ops)
748{ 448{
749 size_t event_size = sizeof (struct inotify_event); 449 struct inotify_handle *ih;
750 struct inotify_device *dev;
751 char __user *start;
752 int ret;
753 DEFINE_WAIT(wait);
754
755 start = buf;
756 dev = file->private_data;
757
758 while (1) {
759 int events;
760
761 prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE);
762 450
763 mutex_lock(&dev->mutex); 451 ih = kmalloc(sizeof(struct inotify_handle), GFP_KERNEL);
764 events = !list_empty(&dev->events); 452 if (unlikely(!ih))
765 mutex_unlock(&dev->mutex); 453 return ERR_PTR(-ENOMEM);
766 if (events) {
767 ret = 0;
768 break;
769 }
770
771 if (file->f_flags & O_NONBLOCK) {
772 ret = -EAGAIN;
773 break;
774 }
775
776 if (signal_pending(current)) {
777 ret = -EINTR;
778 break;
779 }
780
781 schedule();
782 }
783
784 finish_wait(&dev->wq, &wait);
785 if (ret)
786 return ret;
787
788 mutex_lock(&dev->mutex);
789 while (1) {
790 struct inotify_kernel_event *kevent;
791
792 ret = buf - start;
793 if (list_empty(&dev->events))
794 break;
795
796 kevent = inotify_dev_get_event(dev);
797 if (event_size + kevent->event.len > count)
798 break;
799
800 if (copy_to_user(buf, &kevent->event, event_size)) {
801 ret = -EFAULT;
802 break;
803 }
804 buf += event_size;
805 count -= event_size;
806
807 if (kevent->name) {
808 if (copy_to_user(buf, kevent->name, kevent->event.len)){
809 ret = -EFAULT;
810 break;
811 }
812 buf += kevent->event.len;
813 count -= kevent->event.len;
814 }
815 454
816 remove_kevent(dev, kevent); 455 idr_init(&ih->idr);
817 } 456 INIT_LIST_HEAD(&ih->watches);
818 mutex_unlock(&dev->mutex); 457 mutex_init(&ih->mutex);
458 ih->last_wd = 0;
459 ih->in_ops = ops;
460 atomic_set(&ih->count, 0);
461 get_inotify_handle(ih);
819 462
820 return ret; 463 return ih;
821} 464}
465EXPORT_SYMBOL_GPL(inotify_init);
822 466
823static int inotify_release(struct inode *ignored, struct file *file) 467/**
468 * inotify_destroy - clean up and destroy an inotify instance
469 * @ih: inotify handle
470 */
471void inotify_destroy(struct inotify_handle *ih)
824{ 472{
825 struct inotify_device *dev = file->private_data;
826
827 /* 473 /*
828 * Destroy all of the watches on this device. Unfortunately, not very 474 * Destroy all of the watches for this handle. Unfortunately, not very
829 * pretty. We cannot do a simple iteration over the list, because we 475 * pretty. We cannot do a simple iteration over the list, because we
830 * do not know the inode until we iterate to the watch. But we need to 476 * do not know the inode until we iterate to the watch. But we need to
831 * hold inode->inotify_mutex before dev->mutex. The following works. 477 * hold inode->inotify_mutex before ih->mutex. The following works.
832 */ 478 */
833 while (1) { 479 while (1) {
834 struct inotify_watch *watch; 480 struct inotify_watch *watch;
835 struct list_head *watches; 481 struct list_head *watches;
836 struct inode *inode; 482 struct inode *inode;
837 483
838 mutex_lock(&dev->mutex); 484 mutex_lock(&ih->mutex);
839 watches = &dev->watches; 485 watches = &ih->watches;
840 if (list_empty(watches)) { 486 if (list_empty(watches)) {
841 mutex_unlock(&dev->mutex); 487 mutex_unlock(&ih->mutex);
842 break; 488 break;
843 } 489 }
844 watch = list_entry(watches->next, struct inotify_watch, d_list); 490 watch = list_entry(watches->next, struct inotify_watch, h_list);
845 get_inotify_watch(watch); 491 get_inotify_watch(watch);
846 mutex_unlock(&dev->mutex); 492 mutex_unlock(&ih->mutex);
847 493
848 inode = watch->inode; 494 inode = watch->inode;
849 mutex_lock(&inode->inotify_mutex); 495 mutex_lock(&inode->inotify_mutex);
850 mutex_lock(&dev->mutex); 496 mutex_lock(&ih->mutex);
851 497
852 /* make sure we didn't race with another list removal */ 498 /* make sure we didn't race with another list removal */
853 if (likely(idr_find(&dev->idr, watch->wd))) 499 if (likely(idr_find(&ih->idr, watch->wd))) {
854 remove_watch_no_event(watch, dev); 500 remove_watch_no_event(watch, ih);
501 put_inotify_watch(watch);
502 }
855 503
856 mutex_unlock(&dev->mutex); 504 mutex_unlock(&ih->mutex);
857 mutex_unlock(&inode->inotify_mutex); 505 mutex_unlock(&inode->inotify_mutex);
858 put_inotify_watch(watch); 506 put_inotify_watch(watch);
859 } 507 }
860 508
861 /* destroy all of the events on this device */ 509 /* free this handle: the put matching the get in inotify_init() */
862 mutex_lock(&dev->mutex); 510 put_inotify_handle(ih);
863 while (!list_empty(&dev->events))
864 inotify_dev_event_dequeue(dev);
865 mutex_unlock(&dev->mutex);
866
867 /* free this device: the put matching the get in inotify_init() */
868 put_inotify_dev(dev);
869
870 return 0;
871} 511}
512EXPORT_SYMBOL_GPL(inotify_destroy);
872 513
873/* 514/**
874 * inotify_ignore - remove a given wd from this inotify instance. 515 * inotify_find_update_watch - find and update the mask of an existing watch
516 * @ih: inotify handle
517 * @inode: inode's watch to update
518 * @mask: mask of events to watch
875 * 519 *
876 * Can sleep. 520 * Caller must pin given inode (via nameidata).
877 */ 521 */
878static int inotify_ignore(struct inotify_device *dev, s32 wd) 522s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode,
523 u32 mask)
879{ 524{
880 struct inotify_watch *watch; 525 struct inotify_watch *old;
881 struct inode *inode; 526 int mask_add = 0;
527 int ret;
882 528
883 mutex_lock(&dev->mutex); 529 if (mask & IN_MASK_ADD)
884 watch = idr_find(&dev->idr, wd); 530 mask_add = 1;
885 if (unlikely(!watch)) { 531
886 mutex_unlock(&dev->mutex); 532 /* don't allow invalid bits: we don't want flags set */
533 mask &= IN_ALL_EVENTS | IN_ONESHOT;
534 if (unlikely(!mask))
887 return -EINVAL; 535 return -EINVAL;
888 }
889 get_inotify_watch(watch);
890 inode = watch->inode;
891 mutex_unlock(&dev->mutex);
892 536
893 mutex_lock(&inode->inotify_mutex); 537 mutex_lock(&inode->inotify_mutex);
894 mutex_lock(&dev->mutex); 538 mutex_lock(&ih->mutex);
895
896 /* make sure that we did not race */
897 if (likely(idr_find(&dev->idr, wd) == watch))
898 remove_watch(watch, dev);
899
900 mutex_unlock(&dev->mutex);
901 mutex_unlock(&inode->inotify_mutex);
902 put_inotify_watch(watch);
903
904 return 0;
905}
906
907static long inotify_ioctl(struct file *file, unsigned int cmd,
908 unsigned long arg)
909{
910 struct inotify_device *dev;
911 void __user *p;
912 int ret = -ENOTTY;
913 539
914 dev = file->private_data; 540 /*
915 p = (void __user *) arg; 541 * Handle the case of re-adding a watch on an (inode,ih) pair that we
916 542 * are already watching. We just update the mask and return its wd.
917 switch (cmd) { 543 */
918 case FIONREAD: 544 old = inode_find_handle(inode, ih);
919 ret = put_user(dev->queue_size, (int __user *) p); 545 if (unlikely(!old)) {
920 break; 546 ret = -ENOENT;
921 } 547 goto out;
922
923 return ret;
924}
925
926static const struct file_operations inotify_fops = {
927 .poll = inotify_poll,
928 .read = inotify_read,
929 .release = inotify_release,
930 .unlocked_ioctl = inotify_ioctl,
931 .compat_ioctl = inotify_ioctl,
932};
933
934asmlinkage long sys_inotify_init(void)
935{
936 struct inotify_device *dev;
937 struct user_struct *user;
938 struct file *filp;
939 int fd, ret;
940
941 fd = get_unused_fd();
942 if (fd < 0)
943 return fd;
944
945 filp = get_empty_filp();
946 if (!filp) {
947 ret = -ENFILE;
948 goto out_put_fd;
949 }
950
951 user = get_uid(current->user);
952 if (unlikely(atomic_read(&user->inotify_devs) >=
953 inotify_max_user_instances)) {
954 ret = -EMFILE;
955 goto out_free_uid;
956 }
957
958 dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL);
959 if (unlikely(!dev)) {
960 ret = -ENOMEM;
961 goto out_free_uid;
962 } 548 }
963 549
964 filp->f_op = &inotify_fops; 550 if (mask_add)
965 filp->f_vfsmnt = mntget(inotify_mnt); 551 old->mask |= mask;
966 filp->f_dentry = dget(inotify_mnt->mnt_root); 552 else
967 filp->f_mapping = filp->f_dentry->d_inode->i_mapping; 553 old->mask = mask;
968 filp->f_mode = FMODE_READ; 554 ret = old->wd;
969 filp->f_flags = O_RDONLY; 555out:
970 filp->private_data = dev; 556 mutex_unlock(&ih->mutex);
971 557 mutex_unlock(&inode->inotify_mutex);
972 idr_init(&dev->idr);
973 INIT_LIST_HEAD(&dev->events);
974 INIT_LIST_HEAD(&dev->watches);
975 init_waitqueue_head(&dev->wq);
976 mutex_init(&dev->mutex);
977 dev->event_count = 0;
978 dev->queue_size = 0;
979 dev->max_events = inotify_max_queued_events;
980 dev->user = user;
981 dev->last_wd = 0;
982 atomic_set(&dev->count, 0);
983
984 get_inotify_dev(dev);
985 atomic_inc(&user->inotify_devs);
986 fd_install(fd, filp);
987
988 return fd;
989out_free_uid:
990 free_uid(user);
991 put_filp(filp);
992out_put_fd:
993 put_unused_fd(fd);
994 return ret; 558 return ret;
995} 559}
560EXPORT_SYMBOL_GPL(inotify_find_update_watch);
996 561
997asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask) 562/**
563 * inotify_add_watch - add a watch to an inotify instance
564 * @ih: inotify handle
565 * @watch: caller allocated watch structure
566 * @inode: inode to watch
567 * @mask: mask of events to watch
568 *
569 * Caller must pin given inode (via nameidata).
570 * Caller must ensure it only calls inotify_add_watch() once per watch.
571 * Calls inotify_handle_get_wd() so may sleep.
572 */
573s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch,
574 struct inode *inode, u32 mask)
998{ 575{
999 struct inotify_watch *watch, *old; 576 int ret = 0;
1000 struct inode *inode;
1001 struct inotify_device *dev;
1002 struct nameidata nd;
1003 struct file *filp;
1004 int ret, fput_needed;
1005 int mask_add = 0;
1006 unsigned flags = 0;
1007
1008 filp = fget_light(fd, &fput_needed);
1009 if (unlikely(!filp))
1010 return -EBADF;
1011 577
1012 /* verify that this is indeed an inotify instance */ 578 /* don't allow invalid bits: we don't want flags set */
1013 if (unlikely(filp->f_op != &inotify_fops)) { 579 mask &= IN_ALL_EVENTS | IN_ONESHOT;
1014 ret = -EINVAL; 580 if (unlikely(!mask))
1015 goto fput_and_out; 581 return -EINVAL;
1016 } 582 watch->mask = mask;
1017 583
1018 if (!(mask & IN_DONT_FOLLOW)) 584 mutex_lock(&inode->inotify_mutex);
1019 flags |= LOOKUP_FOLLOW; 585 mutex_lock(&ih->mutex);
1020 if (mask & IN_ONLYDIR)
1021 flags |= LOOKUP_DIRECTORY;
1022 586
1023 ret = find_inode(path, &nd, flags); 587 /* Initialize a new watch */
588 ret = inotify_handle_get_wd(ih, watch);
1024 if (unlikely(ret)) 589 if (unlikely(ret))
1025 goto fput_and_out; 590 goto out;
1026 591 ret = watch->wd;
1027 /* inode held in place by reference to nd; dev by fget on fd */
1028 inode = nd.dentry->d_inode;
1029 dev = filp->private_data;
1030
1031 mutex_lock(&inode->inotify_mutex);
1032 mutex_lock(&dev->mutex);
1033 592
1034 if (mask & IN_MASK_ADD) 593 atomic_set(&watch->count, 0);
1035 mask_add = 1; 594 INIT_LIST_HEAD(&watch->h_list);
595 INIT_LIST_HEAD(&watch->i_list);
1036 596
1037 /* don't let user-space set invalid bits: we don't want flags set */ 597 /* save a reference to handle and bump the count to make it official */
1038 mask &= IN_ALL_EVENTS | IN_ONESHOT; 598 get_inotify_handle(ih);
1039 if (unlikely(!mask)) { 599 watch->ih = ih;
1040 ret = -EINVAL;
1041 goto out;
1042 }
1043 600
1044 /* 601 /*
1045 * Handle the case of re-adding a watch on an (inode,dev) pair that we 602 * Save a reference to the inode and bump the ref count to make it
1046 * are already watching. We just update the mask and return its wd. 603 * official. We hold a reference to nameidata, which makes this safe.
1047 */ 604 */
1048 old = inode_find_dev(inode, dev); 605 watch->inode = igrab(inode);
1049 if (unlikely(old)) {
1050 if (mask_add)
1051 old->mask |= mask;
1052 else
1053 old->mask = mask;
1054 ret = old->wd;
1055 goto out;
1056 }
1057 606
1058 watch = create_watch(dev, mask, inode); 607 get_inotify_watch(watch); /* initial get */
1059 if (unlikely(IS_ERR(watch))) {
1060 ret = PTR_ERR(watch);
1061 goto out;
1062 }
1063 608
1064 if (!inotify_inode_watched(inode)) 609 if (!inotify_inode_watched(inode))
1065 set_dentry_child_flags(inode, 1); 610 set_dentry_child_flags(inode, 1);
1066 611
1067 /* Add the watch to the device's and the inode's list */ 612 /* Add the watch to the handle's and the inode's list */
1068 list_add(&watch->d_list, &dev->watches); 613 list_add(&watch->h_list, &ih->watches);
1069 list_add(&watch->i_list, &inode->inotify_watches); 614 list_add(&watch->i_list, &inode->inotify_watches);
1070 ret = watch->wd;
1071out: 615out:
1072 mutex_unlock(&dev->mutex); 616 mutex_unlock(&ih->mutex);
1073 mutex_unlock(&inode->inotify_mutex); 617 mutex_unlock(&inode->inotify_mutex);
1074 path_release(&nd);
1075fput_and_out:
1076 fput_light(filp, fput_needed);
1077 return ret; 618 return ret;
1078} 619}
620EXPORT_SYMBOL_GPL(inotify_add_watch);
1079 621
1080asmlinkage long sys_inotify_rm_watch(int fd, u32 wd) 622/**
623 * inotify_rm_wd - remove a watch from an inotify instance
624 * @ih: inotify handle
625 * @wd: watch descriptor to remove
626 *
627 * Can sleep.
628 */
629int inotify_rm_wd(struct inotify_handle *ih, u32 wd)
1081{ 630{
1082 struct file *filp; 631 struct inotify_watch *watch;
1083 struct inotify_device *dev; 632 struct inode *inode;
1084 int ret, fput_needed;
1085
1086 filp = fget_light(fd, &fput_needed);
1087 if (unlikely(!filp))
1088 return -EBADF;
1089 633
1090 /* verify that this is indeed an inotify instance */ 634 mutex_lock(&ih->mutex);
1091 if (unlikely(filp->f_op != &inotify_fops)) { 635 watch = idr_find(&ih->idr, wd);
1092 ret = -EINVAL; 636 if (unlikely(!watch)) {
1093 goto out; 637 mutex_unlock(&ih->mutex);
638 return -EINVAL;
1094 } 639 }
640 get_inotify_watch(watch);
641 inode = watch->inode;
642 mutex_unlock(&ih->mutex);
1095 643
1096 dev = filp->private_data; 644 mutex_lock(&inode->inotify_mutex);
1097 ret = inotify_ignore(dev, wd); 645 mutex_lock(&ih->mutex);
1098 646
1099out: 647 /* make sure that we did not race */
1100 fput_light(filp, fput_needed); 648 if (likely(idr_find(&ih->idr, wd) == watch))
1101 return ret; 649 remove_watch(watch, ih);
1102}
1103 650
1104static struct super_block * 651 mutex_unlock(&ih->mutex);
1105inotify_get_sb(struct file_system_type *fs_type, int flags, 652 mutex_unlock(&inode->inotify_mutex);
1106 const char *dev_name, void *data) 653 put_inotify_watch(watch);
1107{
1108 return get_sb_pseudo(fs_type, "inotify", NULL, 0xBAD1DEA);
1109}
1110 654
1111static struct file_system_type inotify_fs_type = { 655 return 0;
1112 .name = "inotifyfs", 656}
1113 .get_sb = inotify_get_sb, 657EXPORT_SYMBOL_GPL(inotify_rm_wd);
1114 .kill_sb = kill_anon_super,
1115};
1116 658
1117/* 659/*
1118 * inotify_setup - Our initialization function. Note that we cannnot return 660 * inotify_setup - core initialization function
1119 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
1120 * must result in panic().
1121 */ 661 */
1122static int __init inotify_setup(void) 662static int __init inotify_setup(void)
1123{ 663{
1124 int ret;
1125
1126 ret = register_filesystem(&inotify_fs_type);
1127 if (unlikely(ret))
1128 panic("inotify: register_filesystem returned %d!\n", ret);
1129
1130 inotify_mnt = kern_mount(&inotify_fs_type);
1131 if (IS_ERR(inotify_mnt))
1132 panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt));
1133
1134 inotify_max_queued_events = 16384;
1135 inotify_max_user_instances = 128;
1136 inotify_max_user_watches = 8192;
1137
1138 atomic_set(&inotify_cookie, 0); 664 atomic_set(&inotify_cookie, 0);
1139 665
1140 watch_cachep = kmem_cache_create("inotify_watch_cache",
1141 sizeof(struct inotify_watch),
1142 0, SLAB_PANIC, NULL, NULL);
1143 event_cachep = kmem_cache_create("inotify_event_cache",
1144 sizeof(struct inotify_kernel_event),
1145 0, SLAB_PANIC, NULL, NULL);
1146
1147 return 0; 666 return 0;
1148} 667}
1149 668
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-01 05:42:57 -0400