1/*	$NetBSD: vfs_hooks.c,v 1.5 2008/11/19 18:36:07 ad Exp $	*/
2
3/*-
4 * Copyright (c) 2005 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Julio M. Merino Vidal.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * VFS hooks.
34 */
35
36#include <sys/cdefs.h>
37__KERNEL_RCSID(0, "$NetBSD: vfs_hooks.c,v 1.5 2008/11/19 18:36:07 ad Exp $");
38
39#include <sys/param.h>
40#include <sys/queue.h>
41#include <sys/mount.h>
42#include <sys/mutex.h>
43
44LIST_HEAD(vfs_hooks_head, vfs_hooks) vfs_hooks_head =
45    LIST_HEAD_INITIALIZER(vfs_hooks_head);
46
47kmutex_t vfs_hooks_lock;
48
49void
50vfs_hooks_init(void)
51{
52
53	mutex_init(&vfs_hooks_lock, MUTEX_DEFAULT, IPL_NONE);
54}
55
56int
57vfs_hooks_attach(struct vfs_hooks *vfs_hooks)
58{
59
60	mutex_enter(&vfs_hooks_lock);
61	LIST_INSERT_HEAD(&vfs_hooks_head, vfs_hooks, vfs_hooks_list);
62	mutex_exit(&vfs_hooks_lock);
63
64	return (0);
65}
66
67int
68vfs_hooks_detach(struct vfs_hooks *vfs_hooks)
69{
70	struct vfs_hooks *hp;
71	int ret = 0;
72
73	mutex_enter(&vfs_hooks_lock);
74        LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) {
75                if (hp == vfs_hooks) {
76                        LIST_REMOVE(hp, vfs_hooks_list);
77                        break;
78                }
79        }
80        if (hp == NULL)
81       		ret = ESRCH;
82	mutex_exit(&vfs_hooks_lock);
83
84	return (ret);
85}
86
87/*
88 * Macro to be used in one of the vfs_hooks_* function for hooks that
89 * return an error code.  Calls will stop as soon as one of the hooks
90 * fails.
91 */
92#define VFS_HOOKS_W_ERROR(func, fargs, hook, hargs)			\
93int									\
94func fargs								\
95{									\
96	int error;							\
97	struct vfs_hooks *hp;						\
98 									\
99	error = EJUSTRETURN;						\
100 									\
101	mutex_enter(&vfs_hooks_lock);					\
102        LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) {		\
103		if (hp-> hook != NULL) {				\
104			error = hp-> hook hargs;			\
105			if (error != 0)					\
106				break;					\
107		}							\
108	}								\
109	mutex_exit(&vfs_hooks_lock);					\
110 									\
111	return error;							\
112}
113
114/*
115 * Macro to be used in one of the vfs_hooks_* function for hooks that
116 * do not return any error code.  All hooks will be executed
117 * unconditionally.
118 */
119#define VFS_HOOKS_WO_ERROR(func, fargs, hook, hargs)			\
120void									\
121func fargs								\
122{									\
123	struct vfs_hooks *hp;						\
124 									\
125	mutex_enter(&vfs_hooks_lock);					\
126        LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) {		\
127		if (hp-> hook != NULL)					\
128			hp-> hook hargs;				\
129	}								\
130	mutex_exit(&vfs_hooks_lock);					\
131}
132
133/*
134 * Routines to iterate over VFS hooks lists and execute them.
135 */
136
137VFS_HOOKS_WO_ERROR(vfs_hooks_unmount, (struct mount *mp), vh_unmount, (mp));
138VFS_HOOKS_W_ERROR(vfs_hooks_reexport, (struct mount *mp, const char *path, void *data), vh_reexport, (mp, path, data));
139