Loading...
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>
25
26#include <linux/fsnotify_backend.h>
27#include "fsnotify.h"
28
29#include <linux/atomic.h>
30
31/*
32 * Final freeing of a group
33 */
34void fsnotify_final_destroy_group(struct fsnotify_group *group)
35{
36 if (group->ops->free_group_priv)
37 group->ops->free_group_priv(group);
38
39 kfree(group);
40}
41
42/*
43 * Trying to get rid of a group. Remove all marks, flush all events and release
44 * the group reference.
45 * Note that another thread calling fsnotify_clear_marks_by_group() may still
46 * hold a ref to the group.
47 */
48void fsnotify_destroy_group(struct fsnotify_group *group)
49{
50 /* clear all inode marks for this group */
51 fsnotify_clear_marks_by_group(group);
52
53 synchronize_srcu(&fsnotify_mark_srcu);
54
55 /* clear the notification queue of all events */
56 fsnotify_flush_notify(group);
57
58 /*
59 * Destroy overflow event (we cannot use fsnotify_destroy_event() as
60 * that deliberately ignores overflow events.
61 */
62 if (group->overflow_event)
63 group->ops->free_event(group->overflow_event);
64
65 fsnotify_put_group(group);
66}
67
68/*
69 * Get reference to a group.
70 */
71void fsnotify_get_group(struct fsnotify_group *group)
72{
73 atomic_inc(&group->refcnt);
74}
75
76/*
77 * Drop a reference to a group. Free it if it's through.
78 */
79void fsnotify_put_group(struct fsnotify_group *group)
80{
81 if (atomic_dec_and_test(&group->refcnt))
82 fsnotify_final_destroy_group(group);
83}
84
85/*
86 * Create a new fsnotify_group and hold a reference for the group returned.
87 */
88struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
89{
90 struct fsnotify_group *group;
91
92 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
93 if (!group)
94 return ERR_PTR(-ENOMEM);
95
96 /* set to 0 when there a no external references to this group */
97 atomic_set(&group->refcnt, 1);
98 atomic_set(&group->num_marks, 0);
99
100 mutex_init(&group->notification_mutex);
101 INIT_LIST_HEAD(&group->notification_list);
102 init_waitqueue_head(&group->notification_waitq);
103 group->max_events = UINT_MAX;
104
105 mutex_init(&group->mark_mutex);
106 INIT_LIST_HEAD(&group->marks_list);
107
108 group->ops = ops;
109
110 return group;
111}
112
113int fsnotify_fasync(int fd, struct file *file, int on)
114{
115 struct fsnotify_group *group = file->private_data;
116
117 return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
118}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
4 */
5
6#include <linux/list.h>
7#include <linux/mutex.h>
8#include <linux/slab.h>
9#include <linux/srcu.h>
10#include <linux/rculist.h>
11#include <linux/wait.h>
12#include <linux/memcontrol.h>
13
14#include <linux/fsnotify_backend.h>
15#include "fsnotify.h"
16
17#include <linux/atomic.h>
18
19/*
20 * Final freeing of a group
21 */
22static void fsnotify_final_destroy_group(struct fsnotify_group *group)
23{
24 if (group->ops->free_group_priv)
25 group->ops->free_group_priv(group);
26
27 mem_cgroup_put(group->memcg);
28 mutex_destroy(&group->mark_mutex);
29
30 kfree(group);
31}
32
33/*
34 * Stop queueing new events for this group. Once this function returns
35 * fsnotify_add_event() will not add any new events to the group's queue.
36 */
37void fsnotify_group_stop_queueing(struct fsnotify_group *group)
38{
39 spin_lock(&group->notification_lock);
40 group->shutdown = true;
41 spin_unlock(&group->notification_lock);
42}
43
44/*
45 * Trying to get rid of a group. Remove all marks, flush all events and release
46 * the group reference.
47 * Note that another thread calling fsnotify_clear_marks_by_group() may still
48 * hold a ref to the group.
49 */
50void fsnotify_destroy_group(struct fsnotify_group *group)
51{
52 /*
53 * Stop queueing new events. The code below is careful enough to not
54 * require this but fanotify needs to stop queuing events even before
55 * fsnotify_destroy_group() is called and this makes the other callers
56 * of fsnotify_destroy_group() to see the same behavior.
57 */
58 fsnotify_group_stop_queueing(group);
59
60 /* Clear all marks for this group and queue them for destruction */
61 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_ALL_TYPES_MASK);
62
63 /*
64 * Some marks can still be pinned when waiting for response from
65 * userspace. Wait for those now. fsnotify_prepare_user_wait() will
66 * not succeed now so this wait is race-free.
67 */
68 wait_event(group->notification_waitq, !atomic_read(&group->user_waits));
69
70 /*
71 * Wait until all marks get really destroyed. We could actually destroy
72 * them ourselves instead of waiting for worker to do it, however that
73 * would be racy as worker can already be processing some marks before
74 * we even entered fsnotify_destroy_group().
75 */
76 fsnotify_wait_marks_destroyed();
77
78 /*
79 * Since we have waited for fsnotify_mark_srcu in
80 * fsnotify_mark_destroy_list() there can be no outstanding event
81 * notification against this group. So clearing the notification queue
82 * of all events is reliable now.
83 */
84 fsnotify_flush_notify(group);
85
86 /*
87 * Destroy overflow event (we cannot use fsnotify_destroy_event() as
88 * that deliberately ignores overflow events.
89 */
90 if (group->overflow_event)
91 group->ops->free_event(group->overflow_event);
92
93 fsnotify_put_group(group);
94}
95
96/*
97 * Get reference to a group.
98 */
99void fsnotify_get_group(struct fsnotify_group *group)
100{
101 refcount_inc(&group->refcnt);
102}
103
104/*
105 * Drop a reference to a group. Free it if it's through.
106 */
107void fsnotify_put_group(struct fsnotify_group *group)
108{
109 if (refcount_dec_and_test(&group->refcnt))
110 fsnotify_final_destroy_group(group);
111}
112EXPORT_SYMBOL_GPL(fsnotify_put_group);
113
114/*
115 * Create a new fsnotify_group and hold a reference for the group returned.
116 */
117struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
118{
119 struct fsnotify_group *group;
120
121 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
122 if (!group)
123 return ERR_PTR(-ENOMEM);
124
125 /* set to 0 when there a no external references to this group */
126 refcount_set(&group->refcnt, 1);
127 atomic_set(&group->num_marks, 0);
128 atomic_set(&group->user_waits, 0);
129
130 spin_lock_init(&group->notification_lock);
131 INIT_LIST_HEAD(&group->notification_list);
132 init_waitqueue_head(&group->notification_waitq);
133 group->max_events = UINT_MAX;
134
135 mutex_init(&group->mark_mutex);
136 INIT_LIST_HEAD(&group->marks_list);
137
138 group->ops = ops;
139
140 return group;
141}
142EXPORT_SYMBOL_GPL(fsnotify_alloc_group);
143
144int fsnotify_fasync(int fd, struct file *file, int on)
145{
146 struct fsnotify_group *group = file->private_data;
147
148 return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
149}