1/* $NetBSD: layer_subr.c,v 1.39 2022/04/10 09:50:46 andvar Exp $ */ 2 3/* 4 * Copyright (c) 1999 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/* 37 * Copyright (c) 1992, 1993 38 * The Regents of the University of California. All rights reserved. 39 * 40 * This code is derived from software donated to Berkeley by 41 * Jan-Simon Pendry. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * from: Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp 68 * @(#)null_subr.c 8.7 (Berkeley) 5/14/95 69 */ 70 71#include <sys/cdefs.h> 72__KERNEL_RCSID(0, "$NetBSD: layer_subr.c,v 1.39 2022/04/10 09:50:46 andvar Exp $"); 73 74#include <sys/param.h> 75#include <sys/systm.h> 76#include <sys/proc.h> 77#include <sys/time.h> 78#include <sys/vnode.h> 79#include <sys/mount.h> 80#include <sys/namei.h> 81#include <sys/kmem.h> 82 83#include <miscfs/genfs/layer.h> 84#include <miscfs/genfs/layer_extern.h> 85 86#ifdef LAYERFS_DIAGNOSTIC 87int layerfs_debug = 1; 88#endif 89 90/* 91 * layer cache: 92 * Each cache entry holds a reference to the lower vnode 93 * along with a pointer to the alias vnode. When an 94 * entry is added the lower vnode is VREF'd. When the 95 * alias is removed the lower vnode is vrele'd. 96 */ 97 98void 99layerfs_init(void) 100{ 101 /* Nothing. */ 102} 103 104void 105layerfs_done(void) 106{ 107 /* Nothing. */ 108} 109 110/* 111 * layer_node_create: try to find an existing layerfs vnode referring to it, 112 * otherwise make a new vnode which contains a reference to the lower vnode. 113 */ 114int 115layer_node_create(struct mount *mp, struct vnode *lowervp, struct vnode **nvpp) 116{ 117 int error; 118 struct vnode *aliasvp; 119 120 error = vcache_get(mp, &lowervp, sizeof(lowervp), &aliasvp); 121 if (error) 122 return error; 123 124 /* 125 * Now that we acquired a reference on the upper vnode, release one 126 * on the lower node. The existence of the layer_node retains one 127 * reference to the lower node. 128 */ 129 vrele(lowervp); 130 KASSERT(vrefcnt(lowervp) > 0); 131 132#ifdef LAYERFS_DIAGNOSTIC 133 if (layerfs_debug) 134 vprint("layer_node_create: alias", aliasvp); 135#endif 136 *nvpp = aliasvp; 137 return 0; 138} 139 140#ifdef LAYERFS_DIAGNOSTIC 141struct vnode * 142layer_checkvp(struct vnode *vp, const char *fil, int lno) 143{ 144 struct layer_node *a = VTOLAYER(vp); 145#ifdef notyet 146 /* 147 * Can't do this check because vop_reclaim runs 148 * with a funny vop vector. 149 * 150 * WRS - no it doesnt... 151 */ 152 if (vp->v_op != layer_vnodeop_p) { 153 printf ("layer_checkvp: on non-layer-node\n"); 154#ifdef notyet 155 while (layer_checkvp_barrier) /*WAIT*/ ; 156#endif 157 panic("layer_checkvp"); 158 }; 159#endif 160 if (a->layer_lowervp == NULL) { 161 /* Should never happen */ 162 int i; u_long *p; 163 printf("vp = %p, ZERO ptr\n", vp); 164 for (p = (u_long *) a, i = 0; i < 8; i++) 165 printf(" %lx", p[i]); 166 printf("\n"); 167 /* wait for debugger */ 168 panic("layer_checkvp"); 169 } 170 if (vrefcnt(a->layer_lowervp) < 1) { 171 int i; u_long *p; 172 printf("vp = %p, unref'ed lowervp\n", vp); 173 for (p = (u_long *) a, i = 0; i < 8; i++) 174 printf(" %lx", p[i]); 175 printf("\n"); 176 /* wait for debugger */ 177 panic ("layer with unref'ed lowervp"); 178 }; 179#ifdef notnow 180 printf("layer %p/%d -> %p/%d [%s, %d]\n", 181 LAYERTOV(a), vrefcnt(LAYERTOV(a)), 182 a->layer_lowervp, vrefcnt(a->layer_lowervp), 183 fil, lno); 184#endif 185 return a->layer_lowervp; 186} 187#endif 188