blob: 63fc294a469268d06d9ae1cc9f3d19f3ba95f695 [file] [log] [blame]
Eric Paris90586522009-05-21 17:01:20 -04001/*
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
Arun Sharma60063492011-07-26 16:09:06 -070029#include <linux/atomic.h>
Eric Paris90586522009-05-21 17:01:20 -040030
Eric Paris3be25f42009-05-21 17:01:26 -040031/*
Eric Paris90586522009-05-21 17:01:20 -040032 * Final freeing of a group
33 */
Eric Paris3be25f42009-05-21 17:01:26 -040034void fsnotify_final_destroy_group(struct fsnotify_group *group)
Eric Paris90586522009-05-21 17:01:20 -040035{
Eric Parisa2d8bc62009-05-21 17:01:37 -040036 /* clear the notification queue of all events */
37 fsnotify_flush_notify(group);
38
Eric Paris90586522009-05-21 17:01:20 -040039 if (group->ops->free_group_priv)
40 group->ops->free_group_priv(group);
41
42 kfree(group);
43}
44
45/*
Eric Paris3be25f42009-05-21 17:01:26 -040046 * 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{
Eric Parise61ce862009-12-17 21:24:24 -050055 /* clear all inode marks for this group */
Eric Paris3be25f42009-05-21 17:01:26 -040056 fsnotify_clear_marks_by_group(group);
57
Eric Paris75c1be42010-07-28 10:18:38 -040058 synchronize_srcu(&fsnotify_mark_srcu);
59
Eric Paris3be25f42009-05-21 17:01:26 -040060 /* 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/*
Eric Paris90586522009-05-21 17:01:20 -040066 * Drop a reference to a group. Free it if it's through.
67 */
68void fsnotify_put_group(struct fsnotify_group *group)
69{
Eric Paris02436662010-07-28 10:18:39 -040070 if (atomic_dec_and_test(&group->refcnt))
71 fsnotify_destroy_group(group);
Eric Paris90586522009-05-21 17:01:20 -040072}
73
74/*
Eric Parisffab8342009-12-17 21:24:22 -050075 * Create a new fsnotify_group and hold a reference for the group returned.
Eric Paris90586522009-05-21 17:01:20 -040076 */
Eric Paris0d2e2a12009-12-17 21:24:22 -050077struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
Eric Paris90586522009-05-21 17:01:20 -040078{
Eric Paris74be0cc2009-12-17 21:24:22 -050079 struct fsnotify_group *group;
Eric Paris90586522009-05-21 17:01:20 -040080
Eric Parisf0553af2009-12-17 20:12:06 -050081 group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
Eric Paris90586522009-05-21 17:01:20 -040082 if (!group)
83 return ERR_PTR(-ENOMEM);
84
Eric Paris36fddeb2009-12-17 21:24:23 -050085 /* set to 0 when there a no external references to this group */
Eric Paris90586522009-05-21 17:01:20 -040086 atomic_set(&group->refcnt, 1);
Eric Paris36fddeb2009-12-17 21:24:23 -050087 /*
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
Eric Parisa2d8bc62009-05-21 17:01:37 -040093 mutex_init(&group->notification_mutex);
94 INIT_LIST_HEAD(&group->notification_list);
95 init_waitqueue_head(&group->notification_waitq);
Eric Parisa2d8bc62009-05-21 17:01:37 -040096 group->max_events = UINT_MAX;
97
Eric Paris3be25f42009-05-21 17:01:26 -040098 spin_lock_init(&group->mark_lock);
Eric Parise61ce862009-12-17 21:24:24 -050099 INIT_LIST_HEAD(&group->marks_list);
Eric Paris3be25f42009-05-21 17:01:26 -0400100
Eric Paris90586522009-05-21 17:01:20 -0400101 group->ops = ops;
102
Eric Paris90586522009-05-21 17:01:20 -0400103 return group;
104}