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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 /* clear the notification queue of all events */
37 fsnotify_flush_notify(group);
38
39 if (group->ops->free_group_priv)
40 group->ops->free_group_priv(group);
41
42 kfree(group);
43}
44
45/*
46 * Trying to get rid of a group. We need to first get rid of any outstanding
47 * allocations and then free the group. Remember that fsnotify_clear_marks_by_group
48 * could miss marks that are being freed by inode and those marks could still
49 * hold a reference to this group (via group->num_marks) If we get into that
50 * situtation, the fsnotify_final_destroy_group will get called when that final
51 * mark is freed.
52 */
53static void fsnotify_destroy_group(struct fsnotify_group *group)
54{
55 /* clear all inode marks for this group */
56 fsnotify_clear_marks_by_group(group);
57
58 synchronize_srcu(&fsnotify_mark_srcu);
59
60 /* past the point of no return, matches the initial value of 1 */
61 if (atomic_dec_and_test(&group->num_marks))
62 fsnotify_final_destroy_group(group);
63}
64
65/*
66 * Drop a reference to a group. Free it if it's through.
67 */
68void fsnotify_put_group(struct fsnotify_group *group)
69{
70 if (atomic_dec_and_test(&group->refcnt))
71 fsnotify_destroy_group(group);
72}
73
74/*
75 * Create a new fsnotify_group and hold a reference for the group returned.
76 */
77struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
78{
79 struct fsnotify_group *group;
80
81 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
82 if (!group)
83 return ERR_PTR(-ENOMEM);
84
85 /* set to 0 when there a no external references to this group */
86 atomic_set(&group->refcnt, 1);
87 /*
88 * hits 0 when there are no external references AND no marks for
89 * this group
90 */
91 atomic_set(&group->num_marks, 1);
92
93 mutex_init(&group->notification_mutex);
94 INIT_LIST_HEAD(&group->notification_list);
95 init_waitqueue_head(&group->notification_waitq);
96 group->max_events = UINT_MAX;
97
98 spin_lock_init(&group->mark_lock);
99 INIT_LIST_HEAD(&group->marks_list);
100
101 group->ops = ops;
102
103 return group;
104}
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}