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/fs.h>
20#include <linux/init.h>
21#include <linux/kernel.h>
22#include <linux/module.h>
23#include <linux/mount.h>
24#include <linux/mutex.h>
25#include <linux/spinlock.h>
26
27#include <linux/atomic.h>
28
29#include <linux/fsnotify_backend.h>
30#include "fsnotify.h"
31
32void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
33{
34	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
35}
36
37/*
38 * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
39 * any notifier is interested in hearing for this mount point
40 */
41void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
42{
43	struct mount *m = real_mount(mnt);
44
45	spin_lock(&mnt->mnt_root->d_lock);
46	m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
47	spin_unlock(&mnt->mnt_root->d_lock);
48}
49
50void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
51{
52	struct vfsmount *mnt = mark->mnt;
53	struct mount *m = real_mount(mnt);
54
55	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
56	assert_spin_locked(&mark->lock);
57
58	spin_lock(&mnt->mnt_root->d_lock);
59
60	hlist_del_init_rcu(&mark->obj_list);
61	mark->mnt = NULL;
62
63	m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
64	spin_unlock(&mnt->mnt_root->d_lock);
65}
66
67/*
68 * given a group and vfsmount, find the mark associated with that combination.
69 * if found take a reference to that mark and return it, else return NULL
70 */
71struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group,
72						  struct vfsmount *mnt)
73{
74	struct mount *m = real_mount(mnt);
75	struct fsnotify_mark *mark;
76
77	spin_lock(&mnt->mnt_root->d_lock);
78	mark = fsnotify_find_mark(&m->mnt_fsnotify_marks, group);
79	spin_unlock(&mnt->mnt_root->d_lock);
80
81	return mark;
82}
83
84/*
85 * Attach an initialized mark to a given group and vfsmount.
86 * These marks may be used for the fsnotify backend to determine which
87 * event types should be delivered to which groups.
88 */
89int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
90			       struct fsnotify_group *group, struct vfsmount *mnt,
91			       int allow_dups)
92{
93	struct mount *m = real_mount(mnt);
94	int ret;
95
96	mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
97
98	BUG_ON(!mutex_is_locked(&group->mark_mutex));
99	assert_spin_locked(&mark->lock);
100
101	spin_lock(&mnt->mnt_root->d_lock);
102	mark->mnt = mnt;
103	ret = fsnotify_add_mark_list(&m->mnt_fsnotify_marks, mark, allow_dups);
104	m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
105	spin_unlock(&mnt->mnt_root->d_lock);
106
107	return ret;
108}
109