1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software donated to Berkeley by
8 * Jan-Simon Pendry.
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 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#ifndef FS_NULL_H
36#define FS_NULL_H
37
38#define NULLM_CACHE 0x0001
39
40struct null_mount {
41 struct mount *nullm_vfs;
42 struct vnode *nullm_lowerrootvp; /* Ref to lower root vnode */
43 uint64_t nullm_flags;
44 struct mount_upper_node upper_node;
45 struct mount_upper_node notify_node;
46};
47
48#ifdef _KERNEL
49/*
50 * A cache of vnode references
51 */
52struct null_node {
53 LIST_ENTRY(null_node) null_hash; /* Hash list */
54 struct vnode *null_lowervp; /* VREFed once */
55 struct vnode *null_vnode; /* Back pointer */
56 u_int null_flags;
57};
58
59#define NULLV_NOUNLOCK 0x0001
60#define NULLV_DROP 0x0002
61
62#define MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
63#define VTONULL(vp) ((struct null_node *)(vp)->v_data)
64#define NULLTOV(xp) ((xp)->null_vnode)
65
66int nullfs_init(struct vfsconf *vfsp);
67int nullfs_uninit(struct vfsconf *vfsp);
68int null_nodeget(struct mount *mp, struct vnode *target, struct vnode **vpp);
69struct vnode *null_hashget(struct mount *mp, struct vnode *lowervp);
70void null_hashrem(struct null_node *xp);
71int null_bypass(struct vop_generic_args *ap);
72
73#ifdef DIAGNOSTIC
74struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
75#define NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
76#else
77#define NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
78#endif
79
80extern struct vop_vector null_vnodeops;
81
82#ifdef MALLOC_DECLARE
83MALLOC_DECLARE(M_NULLFSNODE);
84#endif
85
86#ifdef NULLFS_DEBUG
87#define NULLFSDEBUG(format, args...) printf(format ,## args)
88#else
89#define NULLFSDEBUG(format, args...)
90#endif /* NULLFS_DEBUG */
91
92#endif /* _KERNEL */
93
94#endif