Commit | Line | Data |
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c82ee6d3 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
90586523 EP |
2 | /* |
3 | * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> | |
90586523 EP |
4 | */ |
5 | ||
6 | #include <linux/dcache.h> | |
7 | #include <linux/fs.h> | |
5a0e3ad6 | 8 | #include <linux/gfp.h> |
90586523 EP |
9 | #include <linux/init.h> |
10 | #include <linux/module.h> | |
7131485a | 11 | #include <linux/mount.h> |
90586523 EP |
12 | #include <linux/srcu.h> |
13 | ||
14 | #include <linux/fsnotify_backend.h> | |
15 | #include "fsnotify.h" | |
16 | ||
3be25f49 EP |
17 | /* |
18 | * Clear all of the marks on an inode when it is being evicted from core | |
19 | */ | |
20 | void __fsnotify_inode_delete(struct inode *inode) | |
21 | { | |
22 | fsnotify_clear_marks_by_inode(inode); | |
23 | } | |
24 | EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); | |
25 | ||
ca9c726e AG |
26 | void __fsnotify_vfsmount_delete(struct vfsmount *mnt) |
27 | { | |
28 | fsnotify_clear_marks_by_mount(mnt); | |
29 | } | |
30 | ||
ebb3b47e JK |
31 | /** |
32 | * fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes. | |
33 | * @sb: superblock being unmounted. | |
34 | * | |
35 | * Called during unmount with no locks held, so needs to be safe against | |
36 | * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block. | |
37 | */ | |
1e6cb723 | 38 | static void fsnotify_unmount_inodes(struct super_block *sb) |
ebb3b47e JK |
39 | { |
40 | struct inode *inode, *iput_inode = NULL; | |
41 | ||
42 | spin_lock(&sb->s_inode_list_lock); | |
43 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { | |
44 | /* | |
45 | * We cannot __iget() an inode in state I_FREEING, | |
46 | * I_WILL_FREE, or I_NEW which is fine because by that point | |
47 | * the inode cannot have any associated watches. | |
48 | */ | |
49 | spin_lock(&inode->i_lock); | |
50 | if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { | |
51 | spin_unlock(&inode->i_lock); | |
52 | continue; | |
53 | } | |
54 | ||
55 | /* | |
56 | * If i_count is zero, the inode cannot have any watches and | |
1751e8a6 | 57 | * doing an __iget/iput with SB_ACTIVE clear would actually |
ebb3b47e JK |
58 | * evict all inodes with zero i_count from icache which is |
59 | * unnecessarily violent and may in fact be illegal to do. | |
1edc8eb2 ES |
60 | * However, we should have been called /after/ evict_inodes |
61 | * removed all zero refcount inodes, in any case. Test to | |
62 | * be sure. | |
ebb3b47e JK |
63 | */ |
64 | if (!atomic_read(&inode->i_count)) { | |
65 | spin_unlock(&inode->i_lock); | |
66 | continue; | |
67 | } | |
68 | ||
69 | __iget(inode); | |
70 | spin_unlock(&inode->i_lock); | |
71 | spin_unlock(&sb->s_inode_list_lock); | |
72 | ||
73 | if (iput_inode) | |
74 | iput(iput_inode); | |
75 | ||
76 | /* for each watch, send FS_UNMOUNT and then remove it */ | |
77 | fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0); | |
78 | ||
79 | fsnotify_inode_delete(inode); | |
80 | ||
81 | iput_inode = inode; | |
82 | ||
04646aeb | 83 | cond_resched(); |
ebb3b47e JK |
84 | spin_lock(&sb->s_inode_list_lock); |
85 | } | |
86 | spin_unlock(&sb->s_inode_list_lock); | |
87 | ||
88 | if (iput_inode) | |
89 | iput(iput_inode); | |
721fb6fb JK |
90 | /* Wait for outstanding inode references from connectors */ |
91 | wait_var_event(&sb->s_fsnotify_inode_refs, | |
92 | !atomic_long_read(&sb->s_fsnotify_inode_refs)); | |
ebb3b47e JK |
93 | } |
94 | ||
1e6cb723 AG |
95 | void fsnotify_sb_delete(struct super_block *sb) |
96 | { | |
97 | fsnotify_unmount_inodes(sb); | |
98 | fsnotify_clear_marks_by_sb(sb); | |
99 | } | |
100 | ||
c28f7e56 EP |
101 | /* |
102 | * Given an inode, first check if we care what happens to our children. Inotify | |
103 | * and dnotify both tell their parents about events. If we care about any event | |
104 | * on a child we run all of our children and set a dentry flag saying that the | |
105 | * parent cares. Thus when an event happens on a child it can quickly tell if | |
106 | * if there is a need to find a parent and send the event to the parent. | |
107 | */ | |
108 | void __fsnotify_update_child_dentry_flags(struct inode *inode) | |
109 | { | |
110 | struct dentry *alias; | |
111 | int watched; | |
112 | ||
113 | if (!S_ISDIR(inode->i_mode)) | |
114 | return; | |
115 | ||
116 | /* determine if the children should tell inode about their events */ | |
117 | watched = fsnotify_inode_watches_children(inode); | |
118 | ||
873feea0 | 119 | spin_lock(&inode->i_lock); |
c28f7e56 EP |
120 | /* run all of the dentries associated with this inode. Since this is a |
121 | * directory, there damn well better only be one item on this list */ | |
946e51f2 | 122 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
c28f7e56 EP |
123 | struct dentry *child; |
124 | ||
125 | /* run all of the children of the original inode and fix their | |
126 | * d_flags to indicate parental interest (their parent is the | |
127 | * original inode) */ | |
2fd6b7f5 | 128 | spin_lock(&alias->d_lock); |
946e51f2 | 129 | list_for_each_entry(child, &alias->d_subdirs, d_child) { |
c28f7e56 EP |
130 | if (!child->d_inode) |
131 | continue; | |
132 | ||
2fd6b7f5 | 133 | spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); |
c28f7e56 EP |
134 | if (watched) |
135 | child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; | |
136 | else | |
137 | child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; | |
138 | spin_unlock(&child->d_lock); | |
139 | } | |
2fd6b7f5 | 140 | spin_unlock(&alias->d_lock); |
c28f7e56 | 141 | } |
873feea0 | 142 | spin_unlock(&inode->i_lock); |
c28f7e56 EP |
143 | } |
144 | ||
145 | /* Notify this dentry's parent about a child's events. */ | |
12c7f9dc | 146 | int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask) |
c28f7e56 EP |
147 | { |
148 | struct dentry *parent; | |
149 | struct inode *p_inode; | |
52420392 | 150 | int ret = 0; |
c28f7e56 | 151 | |
72acc854 | 152 | if (!dentry) |
2069601b | 153 | dentry = path->dentry; |
28c60e37 | 154 | |
c28f7e56 | 155 | if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) |
52420392 | 156 | return 0; |
c28f7e56 | 157 | |
4d4eb366 | 158 | parent = dget_parent(dentry); |
c28f7e56 EP |
159 | p_inode = parent->d_inode; |
160 | ||
b469e7e4 | 161 | if (unlikely(!fsnotify_inode_watches_children(p_inode))) { |
4d4eb366 | 162 | __fsnotify_update_child_dentry_flags(p_inode); |
b469e7e4 | 163 | } else if (p_inode->i_fsnotify_mask & mask & ALL_FSNOTIFY_EVENTS) { |
49d31c2f AV |
164 | struct name_snapshot name; |
165 | ||
c28f7e56 EP |
166 | /* we are notifying a parent so come up with the new mask which |
167 | * specifies these are events which came from a child. */ | |
168 | mask |= FS_EVENT_ON_CHILD; | |
169 | ||
49d31c2f | 170 | take_dentry_name_snapshot(&name, dentry); |
2069601b | 171 | if (path) |
52420392 | 172 | ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, |
25b229df | 173 | &name.name, 0); |
28c60e37 | 174 | else |
52420392 | 175 | ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, |
25b229df | 176 | &name.name, 0); |
49d31c2f | 177 | release_dentry_name_snapshot(&name); |
c28f7e56 EP |
178 | } |
179 | ||
4d4eb366 | 180 | dput(parent); |
52420392 EP |
181 | |
182 | return ret; | |
c28f7e56 EP |
183 | } |
184 | EXPORT_SYMBOL_GPL(__fsnotify_parent); | |
185 | ||
fd657170 | 186 | static int send_to_group(struct inode *to_tell, |
e637835e | 187 | __u32 mask, const void *data, |
613a807f | 188 | int data_is, u32 cookie, |
e43e9c33 | 189 | const struct qstr *file_name, |
9385a84d | 190 | struct fsnotify_iter_info *iter_info) |
7131485a | 191 | { |
faa9560a | 192 | struct fsnotify_group *group = NULL; |
007d1e83 | 193 | __u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS); |
92183a42 AG |
194 | __u32 marks_mask = 0; |
195 | __u32 marks_ignored_mask = 0; | |
3dca1a74 AG |
196 | struct fsnotify_mark *mark; |
197 | int type; | |
613a807f | 198 | |
5b0457ad | 199 | if (WARN_ON(!iter_info->report_mask)) |
faa9560a | 200 | return 0; |
ce8f76fb EP |
201 | |
202 | /* clear ignored on inode modification */ | |
203 | if (mask & FS_MODIFY) { | |
3dca1a74 AG |
204 | fsnotify_foreach_obj_type(type) { |
205 | if (!fsnotify_iter_should_report_type(iter_info, type)) | |
206 | continue; | |
207 | mark = iter_info->marks[type]; | |
208 | if (mark && | |
209 | !(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) | |
210 | mark->ignored_mask = 0; | |
211 | } | |
ce8f76fb | 212 | } |
613a807f | 213 | |
3dca1a74 AG |
214 | fsnotify_foreach_obj_type(type) { |
215 | if (!fsnotify_iter_should_report_type(iter_info, type)) | |
216 | continue; | |
217 | mark = iter_info->marks[type]; | |
218 | /* does the object mark tell us to do something? */ | |
219 | if (mark) { | |
220 | group = mark->group; | |
221 | marks_mask |= mark->mask; | |
222 | marks_ignored_mask |= mark->ignored_mask; | |
223 | } | |
ce8f76fb EP |
224 | } |
225 | ||
3dca1a74 | 226 | pr_debug("%s: group=%p to_tell=%p mask=%x marks_mask=%x marks_ignored_mask=%x" |
7053aee2 | 227 | " data=%p data_is=%d cookie=%d\n", |
3dca1a74 AG |
228 | __func__, group, to_tell, mask, marks_mask, marks_ignored_mask, |
229 | data, data_is, cookie); | |
faa9560a | 230 | |
92183a42 | 231 | if (!(test_mask & marks_mask & ~marks_ignored_mask)) |
613a807f EP |
232 | return 0; |
233 | ||
5b0457ad | 234 | return group->ops->handle_event(group, to_tell, mask, data, data_is, |
9385a84d | 235 | file_name, cookie, iter_info); |
7131485a EP |
236 | } |
237 | ||
3427ce71 MS |
238 | static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp) |
239 | { | |
240 | struct fsnotify_mark_connector *conn; | |
241 | struct hlist_node *node = NULL; | |
242 | ||
243 | conn = srcu_dereference(*connp, &fsnotify_mark_srcu); | |
244 | if (conn) | |
245 | node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu); | |
246 | ||
247 | return hlist_entry_safe(node, struct fsnotify_mark, obj_list); | |
248 | } | |
249 | ||
250 | static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark) | |
251 | { | |
252 | struct hlist_node *node = NULL; | |
253 | ||
254 | if (mark) | |
255 | node = srcu_dereference(mark->obj_list.next, | |
256 | &fsnotify_mark_srcu); | |
257 | ||
258 | return hlist_entry_safe(node, struct fsnotify_mark, obj_list); | |
259 | } | |
260 | ||
d9a6f30b AG |
261 | /* |
262 | * iter_info is a multi head priority queue of marks. | |
263 | * Pick a subset of marks from queue heads, all with the | |
264 | * same group and set the report_mask for selected subset. | |
265 | * Returns the report_mask of the selected subset. | |
266 | */ | |
267 | static unsigned int fsnotify_iter_select_report_types( | |
268 | struct fsnotify_iter_info *iter_info) | |
269 | { | |
47d9c7cc AG |
270 | struct fsnotify_group *max_prio_group = NULL; |
271 | struct fsnotify_mark *mark; | |
272 | int type; | |
273 | ||
274 | /* Choose max prio group among groups of all queue heads */ | |
275 | fsnotify_foreach_obj_type(type) { | |
276 | mark = iter_info->marks[type]; | |
277 | if (mark && | |
278 | fsnotify_compare_groups(max_prio_group, mark->group) > 0) | |
279 | max_prio_group = mark->group; | |
280 | } | |
d9a6f30b | 281 | |
47d9c7cc | 282 | if (!max_prio_group) |
d9a6f30b AG |
283 | return 0; |
284 | ||
47d9c7cc | 285 | /* Set the report mask for marks from same group as max prio group */ |
d9a6f30b | 286 | iter_info->report_mask = 0; |
47d9c7cc AG |
287 | fsnotify_foreach_obj_type(type) { |
288 | mark = iter_info->marks[type]; | |
289 | if (mark && | |
290 | fsnotify_compare_groups(max_prio_group, mark->group) == 0) | |
291 | fsnotify_iter_set_report_type(iter_info, type); | |
292 | } | |
d9a6f30b AG |
293 | |
294 | return iter_info->report_mask; | |
295 | } | |
296 | ||
297 | /* | |
298 | * Pop from iter_info multi head queue, the marks that were iterated in the | |
299 | * current iteration step. | |
300 | */ | |
301 | static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info) | |
302 | { | |
47d9c7cc | 303 | int type; |
d9a6f30b | 304 | |
47d9c7cc AG |
305 | fsnotify_foreach_obj_type(type) { |
306 | if (fsnotify_iter_should_report_type(iter_info, type)) | |
307 | iter_info->marks[type] = | |
308 | fsnotify_next_mark(iter_info->marks[type]); | |
309 | } | |
d9a6f30b AG |
310 | } |
311 | ||
90586523 EP |
312 | /* |
313 | * This is the main call to fsnotify. The VFS calls into hook specific functions | |
314 | * in linux/fsnotify.h. Those functions then in turn call here. Here will call | |
315 | * out to all of the registered fsnotify_group. Those groups can then use the | |
316 | * notification event in whatever means they feel necessary. | |
317 | */ | |
e637835e | 318 | int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, |
25b229df | 319 | const struct qstr *file_name, u32 cookie) |
90586523 | 320 | { |
3427ce71 | 321 | struct fsnotify_iter_info iter_info = {}; |
45a9fb37 | 322 | struct super_block *sb = to_tell->i_sb; |
60f7ed8c | 323 | struct mount *mnt = NULL; |
45a9fb37 | 324 | __u32 mnt_or_sb_mask = sb->s_fsnotify_mask; |
9385a84d | 325 | int ret = 0; |
007d1e83 | 326 | __u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS); |
90586523 | 327 | |
60f7ed8c | 328 | if (data_is == FSNOTIFY_EVENT_PATH) { |
e637835e | 329 | mnt = real_mount(((const struct path *)data)->mnt); |
45a9fb37 | 330 | mnt_or_sb_mask |= mnt->mnt_fsnotify_mask; |
60f7ed8c | 331 | } |
b469e7e4 AG |
332 | /* An event "on child" is not intended for a mount/sb mark */ |
333 | if (mask & FS_EVENT_ON_CHILD) | |
334 | mnt_or_sb_mask = 0; | |
613a807f | 335 | |
7c49b861 DH |
336 | /* |
337 | * Optimization: srcu_read_lock() has a memory barrier which can | |
338 | * be expensive. It protects walking the *_fsnotify_marks lists. | |
339 | * However, if we do not walk the lists, we do not have to do | |
340 | * SRCU because we have no references to any objects and do not | |
341 | * need SRCU to keep them "alive". | |
342 | */ | |
45a9fb37 AG |
343 | if (!to_tell->i_fsnotify_marks && !sb->s_fsnotify_marks && |
344 | (!mnt || !mnt->mnt_fsnotify_marks)) | |
7c49b861 | 345 | return 0; |
613a807f EP |
346 | /* |
347 | * if this is a modify event we may need to clear the ignored masks | |
60f7ed8c | 348 | * otherwise return if neither the inode nor the vfsmount/sb care about |
613a807f EP |
349 | * this type of event. |
350 | */ | |
351 | if (!(mask & FS_MODIFY) && | |
60f7ed8c | 352 | !(test_mask & (to_tell->i_fsnotify_mask | mnt_or_sb_mask))) |
613a807f | 353 | return 0; |
3a9fb89f | 354 | |
9385a84d | 355 | iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu); |
7131485a | 356 | |
9bdda4e9 AG |
357 | iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] = |
358 | fsnotify_first_mark(&to_tell->i_fsnotify_marks); | |
45a9fb37 AG |
359 | iter_info.marks[FSNOTIFY_OBJ_TYPE_SB] = |
360 | fsnotify_first_mark(&sb->s_fsnotify_marks); | |
9bdda4e9 | 361 | if (mnt) { |
47d9c7cc | 362 | iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] = |
3427ce71 | 363 | fsnotify_first_mark(&mnt->mnt_fsnotify_marks); |
90586523 | 364 | } |
75c1be48 | 365 | |
8edc6e16 | 366 | /* |
60f7ed8c AG |
367 | * We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark |
368 | * ignore masks are properly reflected for mount/sb mark notifications. | |
8edc6e16 JK |
369 | * That's why this traversal is so complicated... |
370 | */ | |
d9a6f30b | 371 | while (fsnotify_iter_select_report_types(&iter_info)) { |
5b0457ad | 372 | ret = send_to_group(to_tell, mask, data, data_is, cookie, |
e43e9c33 | 373 | file_name, &iter_info); |
613a807f | 374 | |
ff8bcbd0 EP |
375 | if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS)) |
376 | goto out; | |
377 | ||
d9a6f30b | 378 | fsnotify_iter_next(&iter_info); |
7131485a | 379 | } |
ff8bcbd0 EP |
380 | ret = 0; |
381 | out: | |
9385a84d | 382 | srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx); |
c4ec54b4 | 383 | |
98b5c10d | 384 | return ret; |
90586523 EP |
385 | } |
386 | EXPORT_SYMBOL_GPL(fsnotify); | |
387 | ||
388 | static __init int fsnotify_init(void) | |
389 | { | |
75c1be48 EP |
390 | int ret; |
391 | ||
66917a31 | 392 | BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 25); |
20dee624 | 393 | |
75c1be48 EP |
394 | ret = init_srcu_struct(&fsnotify_mark_srcu); |
395 | if (ret) | |
396 | panic("initializing fsnotify_mark_srcu"); | |
397 | ||
9dd813c1 JK |
398 | fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector, |
399 | SLAB_PANIC); | |
400 | ||
75c1be48 | 401 | return 0; |
90586523 | 402 | } |
75c1be48 | 403 | core_initcall(fsnotify_init); |