1 /* $NetBSD: layer_subr.c,v 1.36 2014/05/25 13:51:25 hannken 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 1.36 2014/05/25 13:51:25 hannken 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 #include <sys/malloc.h> 83 84 #include <miscfs/genfs/layer.h> 85 #include <miscfs/genfs/layer_extern.h> 86 87 #ifdef LAYERFS_DIAGNOSTIC 88 int layerfs_debug = 1; 89 #endif 90 91 /* 92 * layer cache: 93 * Each cache entry holds a reference to the lower vnode 94 * along with a pointer to the alias vnode. When an 95 * entry is added the lower vnode is VREF'd. When the 96 * alias is removed the lower vnode is vrele'd. 97 */ 98 99 void 100 layerfs_init(void) 101 { 102 /* Nothing. */ 103 } 104 105 void 106 layerfs_done(void) 107 { 108 /* Nothing. */ 109 } 110 111 /* 112 * layer_node_create: try to find an existing layerfs vnode refering to it, 113 * otherwise make a new vnode which contains a reference to the lower vnode. 114 */ 115 int 116 layer_node_create(struct mount *mp, struct vnode *lowervp, struct vnode **nvpp) 117 { 118 int error; 119 struct vnode *aliasvp; 120 121 error = vcache_get(mp, &lowervp, sizeof(lowervp), &aliasvp); 122 if (error) 123 return error; 124 125 /* 126 * Now that we acquired a reference on the upper vnode, release one 127 * on the lower node. The existence of the layer_node retains one 128 * reference to the lower node. 129 */ 130 vrele(lowervp); 131 KASSERT(lowervp->v_usecount > 0); 132 133 #ifdef LAYERFS_DIAGNOSTIC 134 if (layerfs_debug) 135 vprint("layer_node_create: alias", aliasvp); 136 #endif 137 *nvpp = aliasvp; 138 return 0; 139 } 140 141 #ifdef LAYERFS_DIAGNOSTIC 142 struct vnode * 143 layer_checkvp(struct vnode *vp, const char *fil, int lno) 144 { 145 struct layer_node *a = VTOLAYER(vp); 146 #ifdef notyet 147 /* 148 * Can't do this check because vop_reclaim runs 149 * with a funny vop vector. 150 * 151 * WRS - no it doesnt... 152 */ 153 if (vp->v_op != layer_vnodeop_p) { 154 printf ("layer_checkvp: on non-layer-node\n"); 155 #ifdef notyet 156 while (layer_checkvp_barrier) /*WAIT*/ ; 157 #endif 158 panic("layer_checkvp"); 159 }; 160 #endif 161 if (a->layer_lowervp == NULL) { 162 /* Should never happen */ 163 int i; u_long *p; 164 printf("vp = %p, ZERO ptr\n", vp); 165 for (p = (u_long *) a, i = 0; i < 8; i++) 166 printf(" %lx", p[i]); 167 printf("\n"); 168 /* wait for debugger */ 169 panic("layer_checkvp"); 170 } 171 if (a->layer_lowervp->v_usecount < 1) { 172 int i; u_long *p; 173 printf("vp = %p, unref'ed lowervp\n", vp); 174 for (p = (u_long *) a, i = 0; i < 8; i++) 175 printf(" %lx", p[i]); 176 printf("\n"); 177 /* wait for debugger */ 178 panic ("layer with unref'ed lowervp"); 179 }; 180 #ifdef notnow 181 printf("layer %p/%d -> %p/%d [%s, %d]\n", 182 LAYERTOV(a), LAYERTOV(a)->v_usecount, 183 a->layer_lowervp, a->layer_lowervp->v_usecount, 184 fil, lno); 185 #endif 186 return a->layer_lowervp; 187 } 188 #endif 189