tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 */
34static void 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 * Stop queueing new events for this group. Once this function returns
44 * fsnotify_add_event() will not add any new events to the group's queue.
45 */
46void fsnotify_group_stop_queueing(struct fsnotify_group *group)
47{
48 spin_lock(&group->notification_lock);
49 group->shutdown = true;
50 spin_unlock(&group->notification_lock);
51}
52
53/*
54 * Trying to get rid of a group. Remove all marks, flush all events and release
55 * the group reference.
56 * Note that another thread calling fsnotify_clear_marks_by_group() may still
57 * hold a ref to the group.
58 */
59void fsnotify_destroy_group(struct fsnotify_group *group)
60{
61 /*
62 * Stop queueing new events. The code below is careful enough to not
63 * require this but fanotify needs to stop queuing events even before
64 * fsnotify_destroy_group() is called and this makes the other callers
65 * of fsnotify_destroy_group() to see the same behavior.
66 */
67 fsnotify_group_stop_queueing(group);
68
69 /* clear all inode marks for this group, attach them to destroy_list */
70 fsnotify_detach_group_marks(group);
71
72 /*
73 * Wait for fsnotify_mark_srcu period to end and free all marks in
74 * destroy_list
75 */
76 fsnotify_mark_destroy_list();
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 atomic_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 (atomic_dec_and_test(&group->refcnt))
110 fsnotify_final_destroy_group(group);
111}
112
113/*
114 * Create a new fsnotify_group and hold a reference for the group returned.
115 */
116struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
117{
118 struct fsnotify_group *group;
119
120 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
121 if (!group)
122 return ERR_PTR(-ENOMEM);
123
124 /* set to 0 when there a no external references to this group */
125 atomic_set(&group->refcnt, 1);
126 atomic_set(&group->num_marks, 0);
127
128 spin_lock_init(&group->notification_lock);
129 INIT_LIST_HEAD(&group->notification_list);
130 init_waitqueue_head(&group->notification_waitq);
131 group->max_events = UINT_MAX;
132
133 mutex_init(&group->mark_mutex);
134 INIT_LIST_HEAD(&group->marks_list);
135
136 group->ops = ops;
137
138 return group;
139}
140
141int fsnotify_fasync(int fd, struct file *file, int on)
142{
143 struct fsnotify_group *group = file->private_data;
144
145 return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
146}