1/* $NetBSD: overlay_vnops.c,v 1.21 2014/11/10 18:46:33 maxv Exp $ */
2
3/*
4 * Copyright (c) 1999, 2000 National Aeronautics & Space Administration
5 * All rights reserved.
6 *
7 * This software was written by William Studenmund of the
8 * Numerical Aerospace Simulation Facility, NASA Ames Research Center.
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 National Aeronautics & Space Administration
19 * nor the names of its contributors may be used to endorse or promote
20 * products derived from this software without specific prior written
21 * permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
27 * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
28 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * POSSIBILITY OF SUCH DAMAGE.
34 */
35/*
36 * Copyright (c) 1992, 1993
37 * The Regents of the University of California. All rights reserved.
38 *
39 * This code is derived from software contributed to Berkeley by
40 * John Heidemann of the UCLA Ficus project.
41 *
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions
44 * are met:
45 * 1. Redistributions of source code must retain the above copyright
46 * notice, this list of conditions and the following disclaimer.
47 * 2. Redistributions in binary form must reproduce the above copyright
48 * notice, this list of conditions and the following disclaimer in the
49 * documentation and/or other materials provided with the distribution.
50 * 3. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
53 *
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
65 *
66 * @(#)null_vnops.c 8.6 (Berkeley) 5/27/95
67 *
68 * Ancestors:
69 * @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92
70 * $Id: overlay_vnops.c,v 1.21 2014/11/10 18:46:33 maxv Exp $
71 * ...and...
72 * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
73 */
74
75/*
76 * Overlay Layer
77 *
78 * (See mount_overlay(8) for more information.)
79 *
80 * The overlay layer has two purposes. First, it serves as a demonstration
81 * of layering by providing a layer which really does nothing (the null
82 * layer makes the underlying files appear elsewhere in the file hierarchy).
83 * Second, the overlay layer can serve as a prototype layer. Since it
84 * provides all necessary layer framework, new file system layers can be
85 * created very easily by starting with an overlay layer.
86 *
87 * The remainder of this comment examines the overlay layer as a basis
88 * for constructing new layers.
89 *
90 *
91 * INSTANTIATING NEW OVERLAY LAYERS
92 *
93 * New overlay layers are created with mount_overlay(8).
94 * mount_overlay(8) takes two arguments, an ignored string
95 * and the pathname which the overlay will mount over. After
96 * the overlay layer is put into place, all access to the mount
97 * point path will proceed through the overlay layer.
98 *
99 *
100 * OPERATION OF AN OVERLAY LAYER
101 *
102 * The operation of an overlay layer is identical to that of a null
103 * layer. See the null layer (and layerfs) documentation for more info.
104 *
105 *
106 * CREATING OTHER FILE SYSTEM LAYERS
107 *
108 * One of the easiest ways to construct new file system layers is to make
109 * a copy of either the null layer or the overlay layer, rename all files
110 * and variables, and then begin modifying the copy. sed(1) can be used to
111 * easily rename all variables.
112 *
113 * The choice between using a null and an overlay layer depends on
114 * the desirability of retaining access to the underlying filestore.
115 * For instance, the umap filesystem presents both a uid-translated and an
116 * untranslated view of the underlying files, and so it is based off of
117 * the null layer. However a layer implementing Access Control Lists
118 * might prefer to block access to the underlying filestore, for which
119 * the overlay layer is a better basis.
120 *
121 *
122 * INVOKING OPERATIONS ON LOWER LAYERS
123 *
124 * See the null layer documentation.
125 *
126 */
127
128#include <sys/cdefs.h>
129__KERNEL_RCSID(0, "$NetBSD: overlay_vnops.c,v 1.21 2014/11/10 18:46:33 maxv Exp $");
130
131#include <sys/param.h>
132#include <sys/systm.h>
133#include <sys/proc.h>
134#include <sys/time.h>
135#include <sys/vnode.h>
136#include <sys/mount.h>
137#include <sys/namei.h>
138#include <sys/buf.h>
139#include <miscfs/genfs/genfs.h>
140#include <miscfs/overlay/overlay.h>
141#include <miscfs/genfs/layer_extern.h>
142
143/*
144 * Global vfs data structures
145 */
146int (**overlay_vnodeop_p)(void *);
147const struct vnodeopv_entry_desc overlay_vnodeop_entries[] = {
148 { &vop_default_desc, layer_bypass },
149
150 { &vop_lookup_desc, layer_lookup },
151 { &vop_setattr_desc, layer_setattr },
152 { &vop_getattr_desc, layer_getattr },
153 { &vop_access_desc, layer_access },
154 { &vop_fsync_desc, layer_fsync },
155 { &vop_inactive_desc, layer_inactive },
156 { &vop_reclaim_desc, layer_reclaim },
157 { &vop_lock_desc, layer_lock },
158 { &vop_print_desc, layer_print },
159 { &vop_remove_desc, layer_remove },
160 { &vop_rename_desc, layer_rename },
161 { &vop_revoke_desc, layer_revoke },
162 { &vop_rmdir_desc, layer_rmdir },
163
164 { &vop_open_desc, layer_open }, /* mount option handling */
165
166 { &vop_bmap_desc, layer_bmap },
167 { &vop_getpages_desc, layer_getpages },
168 { &vop_putpages_desc, layer_putpages },
169
170 { NULL, NULL }
171};
172const struct vnodeopv_desc overlay_vnodeop_opv_desc =
173 { &overlay_vnodeop_p, overlay_vnodeop_entries };
174