Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * Directory notifications for Linux. | |
3 | * | |
4 | * Copyright (C) 2000,2001,2002 Stephen Rothwell | |
5 | * | |
3c5119c0 EP |
6 | * Copyright (C) 2009 Eric Paris <Red Hat Inc> |
7 | * dnotify was largly rewritten to use the new fsnotify infrastructure | |
8 | * | |
1da177e4 LT |
9 | * This program is free software; you can redistribute it and/or modify it |
10 | * under the terms of the GNU General Public License as published by the | |
11 | * Free Software Foundation; either version 2, or (at your option) any | |
12 | * later version. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, but | |
15 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | * General Public License for more details. | |
18 | */ | |
19 | #include <linux/fs.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/sched.h> | |
22 | #include <linux/dnotify.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/spinlock.h> | |
25 | #include <linux/slab.h> | |
9f3acc31 | 26 | #include <linux/fdtable.h> |
3c5119c0 | 27 | #include <linux/fsnotify_backend.h> |
1da177e4 | 28 | |
fa3536cc | 29 | int dir_notify_enable __read_mostly = 1; |
1da177e4 | 30 | |
3c5119c0 | 31 | static struct kmem_cache *dnotify_struct_cache __read_mostly; |
ef5e2b78 | 32 | static struct kmem_cache *dnotify_mark_cache __read_mostly; |
3c5119c0 | 33 | static struct fsnotify_group *dnotify_group __read_mostly; |
3c5119c0 EP |
34 | |
35 | /* | |
e61ce867 | 36 | * dnotify will attach one of these to each inode (i_fsnotify_marks) which |
3c5119c0 EP |
37 | * is being watched by dnotify. If multiple userspace applications are watching |
38 | * the same directory with dnotify their information is chained in dn | |
39 | */ | |
ef5e2b78 EP |
40 | struct dnotify_mark { |
41 | struct fsnotify_mark fsn_mark; | |
3c5119c0 EP |
42 | struct dnotify_struct *dn; |
43 | }; | |
1da177e4 | 44 | |
3c5119c0 EP |
45 | /* |
46 | * When a process starts or stops watching an inode the set of events which | |
47 | * dnotify cares about for that inode may change. This function runs the | |
48 | * list of everything receiving dnotify events about this directory and calculates | |
49 | * the set of all those events. After it updates what dnotify is interested in | |
50 | * it calls the fsnotify function so it can update the set of all events relevant | |
51 | * to this inode. | |
52 | */ | |
ef5e2b78 | 53 | static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) |
1da177e4 | 54 | { |
66d2b81b | 55 | __u32 new_mask = 0; |
1da177e4 | 56 | struct dnotify_struct *dn; |
ef5e2b78 EP |
57 | struct dnotify_mark *dn_mark = container_of(fsn_mark, |
58 | struct dnotify_mark, | |
59 | fsn_mark); | |
3c5119c0 | 60 | |
ef5e2b78 | 61 | assert_spin_locked(&fsn_mark->lock); |
1da177e4 | 62 | |
ef5e2b78 | 63 | for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next) |
3c5119c0 | 64 | new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); |
66d2b81b | 65 | if (fsn_mark->mask == new_mask) |
3c5119c0 | 66 | return; |
66d2b81b | 67 | fsn_mark->mask = new_mask; |
3c5119c0 | 68 | |
a242677b | 69 | fsnotify_recalc_mask(fsn_mark->connector); |
1da177e4 LT |
70 | } |
71 | ||
3c5119c0 EP |
72 | /* |
73 | * Mains fsnotify call where events are delivered to dnotify. | |
74 | * Find the dnotify mark on the relevant inode, run the list of dnotify structs | |
75 | * on that mark and determine which of them has expressed interest in receiving | |
76 | * events of this type. When found send the correct process and signal and | |
77 | * destroy the dnotify struct if it was not registered to receive multiple | |
78 | * events. | |
79 | */ | |
80 | static int dnotify_handle_event(struct fsnotify_group *group, | |
7053aee2 | 81 | struct inode *inode, |
3cd5eca8 | 82 | u32 mask, const void *data, int data_type, |
9385a84d JK |
83 | const unsigned char *file_name, u32 cookie, |
84 | struct fsnotify_iter_info *iter_info) | |
3c5119c0 | 85 | { |
5b0457ad | 86 | struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info); |
ef5e2b78 | 87 | struct dnotify_mark *dn_mark; |
3c5119c0 EP |
88 | struct dnotify_struct *dn; |
89 | struct dnotify_struct **prev; | |
90 | struct fown_struct *fown; | |
7053aee2 | 91 | __u32 test_mask = mask & ~FS_EVENT_ON_CHILD; |
3c5119c0 | 92 | |
83c4c4b0 JK |
93 | /* not a dir, dnotify doesn't care */ |
94 | if (!S_ISDIR(inode->i_mode)) | |
95 | return 0; | |
96 | ||
5b0457ad AG |
97 | if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info))) |
98 | return 0; | |
ce8f76fb | 99 | |
ce8f76fb | 100 | dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark); |
3c5119c0 | 101 | |
ce8f76fb | 102 | spin_lock(&inode_mark->lock); |
ef5e2b78 | 103 | prev = &dn_mark->dn; |
3c5119c0 | 104 | while ((dn = *prev) != NULL) { |
94552684 | 105 | if ((dn->dn_mask & test_mask) == 0) { |
3c5119c0 EP |
106 | prev = &dn->dn_next; |
107 | continue; | |
108 | } | |
109 | fown = &dn->dn_filp->f_owner; | |
110 | send_sigio(fown, dn->dn_fd, POLL_MSG); | |
111 | if (dn->dn_mask & FS_DN_MULTISHOT) | |
112 | prev = &dn->dn_next; | |
113 | else { | |
114 | *prev = dn->dn_next; | |
115 | kmem_cache_free(dnotify_struct_cache, dn); | |
ce8f76fb | 116 | dnotify_recalc_inode_mask(inode_mark); |
3c5119c0 EP |
117 | } |
118 | } | |
119 | ||
ce8f76fb | 120 | spin_unlock(&inode_mark->lock); |
3c5119c0 EP |
121 | |
122 | return 0; | |
123 | } | |
124 | ||
ef5e2b78 | 125 | static void dnotify_free_mark(struct fsnotify_mark *fsn_mark) |
3c5119c0 | 126 | { |
ef5e2b78 EP |
127 | struct dnotify_mark *dn_mark = container_of(fsn_mark, |
128 | struct dnotify_mark, | |
129 | fsn_mark); | |
3c5119c0 | 130 | |
ef5e2b78 | 131 | BUG_ON(dn_mark->dn); |
3c5119c0 | 132 | |
ef5e2b78 | 133 | kmem_cache_free(dnotify_mark_cache, dn_mark); |
3c5119c0 EP |
134 | } |
135 | ||
c9ea9df3 | 136 | static const struct fsnotify_ops dnotify_fsnotify_ops = { |
3c5119c0 | 137 | .handle_event = dnotify_handle_event, |
054c636e | 138 | .free_mark = dnotify_free_mark, |
3c5119c0 EP |
139 | }; |
140 | ||
141 | /* | |
142 | * Called every time a file is closed. Looks first for a dnotify mark on the | |
e61ce867 | 143 | * inode. If one is found run all of the ->dn structures attached to that |
3c5119c0 EP |
144 | * mark for one relevant to this process closing the file and remove that |
145 | * dnotify_struct. If that was the last dnotify_struct also remove the | |
e61ce867 | 146 | * fsnotify_mark. |
3c5119c0 | 147 | */ |
1da177e4 LT |
148 | void dnotify_flush(struct file *filp, fl_owner_t id) |
149 | { | |
ef5e2b78 EP |
150 | struct fsnotify_mark *fsn_mark; |
151 | struct dnotify_mark *dn_mark; | |
1da177e4 LT |
152 | struct dnotify_struct *dn; |
153 | struct dnotify_struct **prev; | |
154 | struct inode *inode; | |
4712e722 | 155 | bool free = false; |
1da177e4 | 156 | |
496ad9aa | 157 | inode = file_inode(filp); |
1da177e4 LT |
158 | if (!S_ISDIR(inode->i_mode)) |
159 | return; | |
3c5119c0 | 160 | |
b1362edf | 161 | fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, dnotify_group); |
ef5e2b78 | 162 | if (!fsn_mark) |
3c5119c0 | 163 | return; |
ef5e2b78 | 164 | dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); |
3c5119c0 | 165 | |
52f85729 | 166 | mutex_lock(&dnotify_group->mark_mutex); |
3c5119c0 | 167 | |
ef5e2b78 EP |
168 | spin_lock(&fsn_mark->lock); |
169 | prev = &dn_mark->dn; | |
1da177e4 LT |
170 | while ((dn = *prev) != NULL) { |
171 | if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { | |
172 | *prev = dn->dn_next; | |
3c5119c0 | 173 | kmem_cache_free(dnotify_struct_cache, dn); |
ef5e2b78 | 174 | dnotify_recalc_inode_mask(fsn_mark); |
1da177e4 LT |
175 | break; |
176 | } | |
177 | prev = &dn->dn_next; | |
178 | } | |
3c5119c0 | 179 | |
ef5e2b78 | 180 | spin_unlock(&fsn_mark->lock); |
3c5119c0 | 181 | |
52f85729 LS |
182 | /* nothing else could have found us thanks to the dnotify_groups |
183 | mark_mutex */ | |
4712e722 JK |
184 | if (dn_mark->dn == NULL) { |
185 | fsnotify_detach_mark(fsn_mark); | |
186 | free = true; | |
187 | } | |
3c5119c0 | 188 | |
52f85729 | 189 | mutex_unlock(&dnotify_group->mark_mutex); |
3c5119c0 | 190 | |
4712e722 JK |
191 | if (free) |
192 | fsnotify_free_mark(fsn_mark); | |
ef5e2b78 | 193 | fsnotify_put_mark(fsn_mark); |
3c5119c0 EP |
194 | } |
195 | ||
196 | /* this conversion is done only at watch creation */ | |
197 | static __u32 convert_arg(unsigned long arg) | |
198 | { | |
199 | __u32 new_mask = FS_EVENT_ON_CHILD; | |
200 | ||
201 | if (arg & DN_MULTISHOT) | |
202 | new_mask |= FS_DN_MULTISHOT; | |
203 | if (arg & DN_DELETE) | |
204 | new_mask |= (FS_DELETE | FS_MOVED_FROM); | |
205 | if (arg & DN_MODIFY) | |
206 | new_mask |= FS_MODIFY; | |
207 | if (arg & DN_ACCESS) | |
208 | new_mask |= FS_ACCESS; | |
209 | if (arg & DN_ATTRIB) | |
210 | new_mask |= FS_ATTRIB; | |
211 | if (arg & DN_RENAME) | |
212 | new_mask |= FS_DN_RENAME; | |
213 | if (arg & DN_CREATE) | |
214 | new_mask |= (FS_CREATE | FS_MOVED_TO); | |
215 | ||
216 | return new_mask; | |
1da177e4 LT |
217 | } |
218 | ||
3c5119c0 EP |
219 | /* |
220 | * If multiple processes watch the same inode with dnotify there is only one | |
e61ce867 | 221 | * dnotify mark in inode->i_fsnotify_marks but we chain a dnotify_struct |
3c5119c0 EP |
222 | * onto that mark. This function either attaches the new dnotify_struct onto |
223 | * that list, or it |= the mask onto an existing dnofiy_struct. | |
224 | */ | |
ef5e2b78 | 225 | static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark *dn_mark, |
3c5119c0 EP |
226 | fl_owner_t id, int fd, struct file *filp, __u32 mask) |
227 | { | |
228 | struct dnotify_struct *odn; | |
229 | ||
ef5e2b78 | 230 | odn = dn_mark->dn; |
3c5119c0 EP |
231 | while (odn != NULL) { |
232 | /* adding more events to existing dnofiy_struct? */ | |
233 | if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { | |
234 | odn->dn_fd = fd; | |
235 | odn->dn_mask |= mask; | |
236 | return -EEXIST; | |
237 | } | |
238 | odn = odn->dn_next; | |
239 | } | |
240 | ||
241 | dn->dn_mask = mask; | |
242 | dn->dn_fd = fd; | |
243 | dn->dn_filp = filp; | |
244 | dn->dn_owner = id; | |
ef5e2b78 EP |
245 | dn->dn_next = dn_mark->dn; |
246 | dn_mark->dn = dn; | |
3c5119c0 EP |
247 | |
248 | return 0; | |
249 | } | |
250 | ||
251 | /* | |
252 | * When a process calls fcntl to attach a dnotify watch to a directory it ends | |
253 | * up here. Allocate both a mark for fsnotify to add and a dnotify_struct to be | |
254 | * attached to the fsnotify_mark. | |
255 | */ | |
1da177e4 LT |
256 | int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) |
257 | { | |
ef5e2b78 EP |
258 | struct dnotify_mark *new_dn_mark, *dn_mark; |
259 | struct fsnotify_mark *new_fsn_mark, *fsn_mark; | |
1da177e4 | 260 | struct dnotify_struct *dn; |
1da177e4 LT |
261 | struct inode *inode; |
262 | fl_owner_t id = current->files; | |
214b7049 | 263 | struct file *f; |
3c5119c0 EP |
264 | int destroy = 0, error = 0; |
265 | __u32 mask; | |
266 | ||
267 | /* we use these to tell if we need to kfree */ | |
ef5e2b78 | 268 | new_fsn_mark = NULL; |
3c5119c0 | 269 | dn = NULL; |
1da177e4 | 270 | |
3c5119c0 EP |
271 | if (!dir_notify_enable) { |
272 | error = -EINVAL; | |
273 | goto out_err; | |
274 | } | |
275 | ||
276 | /* a 0 mask means we are explicitly removing the watch */ | |
1da177e4 LT |
277 | if ((arg & ~DN_MULTISHOT) == 0) { |
278 | dnotify_flush(filp, id); | |
3c5119c0 EP |
279 | error = 0; |
280 | goto out_err; | |
1da177e4 | 281 | } |
3c5119c0 EP |
282 | |
283 | /* dnotify only works on directories */ | |
496ad9aa | 284 | inode = file_inode(filp); |
3c5119c0 EP |
285 | if (!S_ISDIR(inode->i_mode)) { |
286 | error = -ENOTDIR; | |
287 | goto out_err; | |
1da177e4 LT |
288 | } |
289 | ||
3c5119c0 EP |
290 | /* expect most fcntl to add new rather than augment old */ |
291 | dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL); | |
292 | if (!dn) { | |
293 | error = -ENOMEM; | |
294 | goto out_err; | |
295 | } | |
214b7049 | 296 | |
3c5119c0 | 297 | /* new fsnotify mark, we expect most fcntl calls to add a new mark */ |
ef5e2b78 EP |
298 | new_dn_mark = kmem_cache_alloc(dnotify_mark_cache, GFP_KERNEL); |
299 | if (!new_dn_mark) { | |
3c5119c0 EP |
300 | error = -ENOMEM; |
301 | goto out_err; | |
302 | } | |
1da177e4 | 303 | |
3c5119c0 EP |
304 | /* convert the userspace DN_* "arg" to the internal FS_* defines in fsnotify */ |
305 | mask = convert_arg(arg); | |
1da177e4 | 306 | |
ef5e2b78 EP |
307 | /* set up the new_fsn_mark and new_dn_mark */ |
308 | new_fsn_mark = &new_dn_mark->fsn_mark; | |
054c636e | 309 | fsnotify_init_mark(new_fsn_mark, dnotify_group); |
ef5e2b78 EP |
310 | new_fsn_mark->mask = mask; |
311 | new_dn_mark->dn = NULL; | |
1da177e4 | 312 | |
3c5119c0 | 313 | /* this is needed to prevent the fcntl/close race described below */ |
52f85729 | 314 | mutex_lock(&dnotify_group->mark_mutex); |
1da177e4 | 315 | |
ef5e2b78 | 316 | /* add the new_fsn_mark or find an old one. */ |
b1362edf | 317 | fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, dnotify_group); |
ef5e2b78 EP |
318 | if (fsn_mark) { |
319 | dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); | |
320 | spin_lock(&fsn_mark->lock); | |
3c5119c0 | 321 | } else { |
b3a00660 JK |
322 | error = fsnotify_add_mark_locked(new_fsn_mark, inode, NULL, 0); |
323 | if (error) { | |
324 | mutex_unlock(&dnotify_group->mark_mutex); | |
325 | goto out_err; | |
326 | } | |
ef5e2b78 EP |
327 | spin_lock(&new_fsn_mark->lock); |
328 | fsn_mark = new_fsn_mark; | |
329 | dn_mark = new_dn_mark; | |
330 | /* we used new_fsn_mark, so don't free it */ | |
331 | new_fsn_mark = NULL; | |
3c5119c0 | 332 | } |
1da177e4 | 333 | |
3c5119c0 EP |
334 | rcu_read_lock(); |
335 | f = fcheck(fd); | |
336 | rcu_read_unlock(); | |
1da177e4 | 337 | |
3c5119c0 EP |
338 | /* if (f != filp) means that we lost a race and another task/thread |
339 | * actually closed the fd we are still playing with before we grabbed | |
52f85729 LS |
340 | * the dnotify_groups mark_mutex and fsn_mark->lock. Since closing the |
341 | * fd is the only time we clean up the marks we need to get our mark | |
342 | * off the list. */ | |
3c5119c0 EP |
343 | if (f != filp) { |
344 | /* if we added ourselves, shoot ourselves, it's possible that | |
ef5e2b78 | 345 | * the flush actually did shoot this fsn_mark. That's fine too |
3c5119c0 | 346 | * since multiple calls to destroy_mark is perfectly safe, if |
ef5e2b78 | 347 | * we found a dn_mark already attached to the inode, just sod |
3c5119c0 EP |
348 | * off silently as the flush at close time dealt with it. |
349 | */ | |
ef5e2b78 | 350 | if (dn_mark == new_dn_mark) |
3c5119c0 | 351 | destroy = 1; |
b3a00660 | 352 | error = 0; |
3c5119c0 EP |
353 | goto out; |
354 | } | |
1da177e4 | 355 | |
e0b93edd | 356 | __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); |
3c5119c0 | 357 | |
ef5e2b78 EP |
358 | error = attach_dn(dn, dn_mark, id, fd, filp, mask); |
359 | /* !error means that we attached the dn to the dn_mark, so don't free it */ | |
3c5119c0 EP |
360 | if (!error) |
361 | dn = NULL; | |
362 | /* -EEXIST means that we didn't add this new dn and used an old one. | |
363 | * that isn't an error (and the unused dn should be freed) */ | |
364 | else if (error == -EEXIST) | |
365 | error = 0; | |
366 | ||
ef5e2b78 | 367 | dnotify_recalc_inode_mask(fsn_mark); |
3c5119c0 | 368 | out: |
ef5e2b78 | 369 | spin_unlock(&fsn_mark->lock); |
3c5119c0 EP |
370 | |
371 | if (destroy) | |
4712e722 | 372 | fsnotify_detach_mark(fsn_mark); |
52f85729 | 373 | mutex_unlock(&dnotify_group->mark_mutex); |
4712e722 JK |
374 | if (destroy) |
375 | fsnotify_free_mark(fsn_mark); | |
ef5e2b78 | 376 | fsnotify_put_mark(fsn_mark); |
3c5119c0 | 377 | out_err: |
ef5e2b78 EP |
378 | if (new_fsn_mark) |
379 | fsnotify_put_mark(new_fsn_mark); | |
3c5119c0 EP |
380 | if (dn) |
381 | kmem_cache_free(dnotify_struct_cache, dn); | |
382 | return error; | |
1da177e4 | 383 | } |
1da177e4 LT |
384 | |
385 | static int __init dnotify_init(void) | |
386 | { | |
3c5119c0 | 387 | dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC); |
ef5e2b78 | 388 | dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC); |
3c5119c0 | 389 | |
0d2e2a1d | 390 | dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops); |
3c5119c0 EP |
391 | if (IS_ERR(dnotify_group)) |
392 | panic("unable to allocate fsnotify group for dnotify\n"); | |
1da177e4 LT |
393 | return 0; |
394 | } | |
395 | ||
396 | module_init(dnotify_init) |