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90586523 EP |
1 | /* |
2 | * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2, or (at your option) | |
7 | * any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; see the file COPYING. If not, write to | |
16 | * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
17 | */ | |
18 | ||
19 | #include <linux/list.h> | |
20 | #include <linux/mutex.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/srcu.h> | |
23 | #include <linux/rculist.h> | |
24 | #include <linux/wait.h> | |
fe9d3fa6 | 25 | #include <linux/module.h> |
90586523 EP |
26 | |
27 | #include <linux/fsnotify_backend.h> | |
28 | #include "fsnotify.h" | |
29 | ||
60063497 | 30 | #include <linux/atomic.h> |
90586523 | 31 | |
90586523 EP |
32 | /* |
33 | * Final freeing of a group | |
34 | */ | |
cafbaae8 | 35 | static void fsnotify_final_destroy_group(struct fsnotify_group *group) |
90586523 EP |
36 | { |
37 | if (group->ops->free_group_priv) | |
38 | group->ops->free_group_priv(group); | |
39 | ||
40 | kfree(group); | |
41 | } | |
42 | ||
12703dbf JK |
43 | /* |
44 | * Stop queueing new events for this group. Once this function returns | |
45 | * fsnotify_add_event() will not add any new events to the group's queue. | |
46 | */ | |
47 | void fsnotify_group_stop_queueing(struct fsnotify_group *group) | |
48 | { | |
c21dbe20 | 49 | spin_lock(&group->notification_lock); |
12703dbf | 50 | group->shutdown = true; |
c21dbe20 | 51 | spin_unlock(&group->notification_lock); |
12703dbf JK |
52 | } |
53 | ||
3be25f49 | 54 | /* |
23e964c2 LS |
55 | * Trying to get rid of a group. Remove all marks, flush all events and release |
56 | * the group reference. | |
57 | * Note that another thread calling fsnotify_clear_marks_by_group() may still | |
58 | * hold a ref to the group. | |
3be25f49 | 59 | */ |
d8153d4d | 60 | void fsnotify_destroy_group(struct fsnotify_group *group) |
3be25f49 | 61 | { |
12703dbf JK |
62 | /* |
63 | * Stop queueing new events. The code below is careful enough to not | |
64 | * require this but fanotify needs to stop queuing events even before | |
65 | * fsnotify_destroy_group() is called and this makes the other callers | |
66 | * of fsnotify_destroy_group() to see the same behavior. | |
67 | */ | |
68 | fsnotify_group_stop_queueing(group); | |
69 | ||
f09b04a0 | 70 | /* Clear all marks for this group and queue them for destruction */ |
2e37c6ca JK |
71 | fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_ALL_TYPES); |
72 | ||
73 | /* | |
74 | * Some marks can still be pinned when waiting for response from | |
75 | * userspace. Wait for those now. fsnotify_prepare_user_wait() will | |
76 | * not succeed now so this wait is race-free. | |
77 | */ | |
78 | wait_event(group->notification_waitq, !atomic_read(&group->user_waits)); | |
3be25f49 | 79 | |
35e48176 | 80 | /* |
f09b04a0 JK |
81 | * Wait until all marks get really destroyed. We could actually destroy |
82 | * them ourselves instead of waiting for worker to do it, however that | |
83 | * would be racy as worker can already be processing some marks before | |
84 | * we even entered fsnotify_destroy_group(). | |
35e48176 | 85 | */ |
f09b04a0 | 86 | fsnotify_wait_marks_destroyed(); |
75c1be48 | 87 | |
35e48176 JK |
88 | /* |
89 | * Since we have waited for fsnotify_mark_srcu in | |
90 | * fsnotify_mark_destroy_list() there can be no outstanding event | |
91 | * notification against this group. So clearing the notification queue | |
92 | * of all events is reliable now. | |
93 | */ | |
23e964c2 LS |
94 | fsnotify_flush_notify(group); |
95 | ||
ff57cd58 JK |
96 | /* |
97 | * Destroy overflow event (we cannot use fsnotify_destroy_event() as | |
98 | * that deliberately ignores overflow events. | |
99 | */ | |
100 | if (group->overflow_event) | |
101 | group->ops->free_event(group->overflow_event); | |
102 | ||
23e964c2 | 103 | fsnotify_put_group(group); |
3be25f49 EP |
104 | } |
105 | ||
98612952 LS |
106 | /* |
107 | * Get reference to a group. | |
108 | */ | |
109 | void fsnotify_get_group(struct fsnotify_group *group) | |
110 | { | |
111 | atomic_inc(&group->refcnt); | |
112 | } | |
fe9d3fa6 | 113 | EXPORT_SYMBOL_GPL(fsnotify_get_group); |
98612952 | 114 | |
90586523 EP |
115 | /* |
116 | * Drop a reference to a group. Free it if it's through. | |
117 | */ | |
118 | void fsnotify_put_group(struct fsnotify_group *group) | |
119 | { | |
02436668 | 120 | if (atomic_dec_and_test(&group->refcnt)) |
23e964c2 | 121 | fsnotify_final_destroy_group(group); |
90586523 | 122 | } |
fe9d3fa6 | 123 | EXPORT_SYMBOL_GPL(fsnotify_put_group); |
90586523 | 124 | |
90586523 | 125 | /* |
ffab8340 | 126 | * Create a new fsnotify_group and hold a reference for the group returned. |
90586523 | 127 | */ |
0d2e2a1d | 128 | struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) |
90586523 | 129 | { |
74be0cc8 | 130 | struct fsnotify_group *group; |
90586523 | 131 | |
f0553af0 | 132 | group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); |
90586523 EP |
133 | if (!group) |
134 | return ERR_PTR(-ENOMEM); | |
135 | ||
36fddeba | 136 | /* set to 0 when there a no external references to this group */ |
90586523 | 137 | atomic_set(&group->refcnt, 1); |
23e964c2 | 138 | atomic_set(&group->num_marks, 0); |
abc77577 | 139 | atomic_set(&group->user_waits, 0); |
36fddeba | 140 | |
c21dbe20 | 141 | spin_lock_init(&group->notification_lock); |
a2d8bc6c EP |
142 | INIT_LIST_HEAD(&group->notification_list); |
143 | init_waitqueue_head(&group->notification_waitq); | |
a2d8bc6c EP |
144 | group->max_events = UINT_MAX; |
145 | ||
986ab098 | 146 | mutex_init(&group->mark_mutex); |
e61ce867 | 147 | INIT_LIST_HEAD(&group->marks_list); |
3be25f49 | 148 | |
90586523 EP |
149 | group->ops = ops; |
150 | ||
90586523 EP |
151 | return group; |
152 | } | |
fe9d3fa6 | 153 | EXPORT_SYMBOL_GPL(fsnotify_alloc_group); |
0a6b6bd5 EP |
154 | |
155 | int fsnotify_fasync(int fd, struct file *file, int on) | |
156 | { | |
157 | struct fsnotify_group *group = file->private_data; | |
158 | ||
159 | return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO; | |
160 | } |