| 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 | */ |
| 146 | int (**overlay_vnodeop_p)(void *); |
| 147 | const 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 | }; |
| 172 | const struct vnodeopv_desc overlay_vnodeop_opv_desc = |
| 173 | { &overlay_vnodeop_p, overlay_vnodeop_entries }; |
| 174 | |