| 1 | /* |
| 2 | * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. |
| 3 | * |
| 4 | * @APPLE_LICENSE_HEADER_START@ |
| 5 | * |
| 6 | * The contents of this file constitute Original Code as defined in and |
| 7 | * are subject to the Apple Public Source License Version 1.1 (the |
| 8 | * "License"). You may not use this file except in compliance with the |
| 9 | * License. Please obtain a copy of the License at |
| 10 | * http://www.apple.com/publicsource and read it before using this file. |
| 11 | * |
| 12 | * This Original Code and all software distributed under the License are |
| 13 | * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
| 14 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 15 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
| 16 | * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the |
| 17 | * License for the specific language governing rights and limitations |
| 18 | * under the License. |
| 19 | * |
| 20 | * @APPLE_LICENSE_HEADER_END@ |
| 21 | */ |
| 22 | /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */ |
| 23 | /* |
| 24 | * Copyright (c) 1992, 1993 |
| 25 | * The Regents of the University of California. All rights reserved. |
| 26 | * |
| 27 | * This code is derived from software donated to Berkeley by |
| 28 | * Jan-Simon Pendry. |
| 29 | * |
| 30 | * Redistribution and use in source and binary forms, with or without |
| 31 | * modification, are permitted provided that the following conditions |
| 32 | * are met: |
| 33 | * 1. Redistributions of source code must retain the above copyright |
| 34 | * notice, this list of conditions and the following disclaimer. |
| 35 | * 2. Redistributions in binary form must reproduce the above copyright |
| 36 | * notice, this list of conditions and the following disclaimer in the |
| 37 | * documentation and/or other materials provided with the distribution. |
| 38 | * 3. All advertising materials mentioning features or use of this software |
| 39 | * must display the following acknowledgement: |
| 40 | * This product includes software developed by the University of |
| 41 | * California, Berkeley and its contributors. |
| 42 | * 4. Neither the name of the University nor the names of its contributors |
| 43 | * may be used to endorse or promote products derived from this software |
| 44 | * without specific prior written permission. |
| 45 | * |
| 46 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 47 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 48 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 49 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 50 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 51 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 52 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 53 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 54 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 55 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 56 | * SUCH DAMAGE. |
| 57 | * |
| 58 | * @(#)null_subr.c 8.7 (Berkeley) 5/14/95 |
| 59 | * |
| 60 | * null_subr.c 8.4 (Berkeley) 1/21/94 |
| 61 | */ |
| 62 | |
| 63 | #include <sys/param.h> |
| 64 | #include <sys/systm.h> |
| 65 | #include <sys/proc.h> |
| 66 | #include <sys/time.h> |
| 67 | #include <sys/types.h> |
| 68 | #include <sys/vnode.h> |
| 69 | #include <sys/mount_internal.h> |
| 70 | #include <sys/namei.h> |
| 71 | #include <sys/malloc.h> |
| 72 | #include <sys/ubc.h> |
| 73 | #include <miscfs/nullfs/null.h> |
| 74 | |
| 75 | #define LOG2_SIZEVNODE 7 /* log2(sizeof struct vnode) */ |
| 76 | #define NNULLNODECACHE 16 |
| 77 | |
| 78 | /* |
| 79 | * Null layer cache: |
| 80 | * Each cache entry holds a reference to the lower vnode |
| 81 | * along with a pointer to the alias vnode. When an |
| 82 | * entry is added the lower vnode is vnode_get'd. When the |
| 83 | * alias is removed the lower vnode is vnode_put'd. |
| 84 | */ |
| 85 | |
| 86 | #define NULL_NHASH(vp) \ |
| 87 | (&null_node_hashtbl[(((u_long)vp)>>LOG2_SIZEVNODE) & null_node_hash]) |
| 88 | LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl; |
| 89 | u_long null_node_hash; |
| 90 | |
| 91 | /* |
| 92 | * Initialise cache headers |
| 93 | */ |
| 94 | nullfs_init() |
| 95 | { |
| 96 | |
| 97 | #ifdef NULLFS_DIAGNOSTIC |
| 98 | printf("nullfs_init\n"); /* printed during system boot */ |
| 99 | #endif |
| 100 | null_node_hashtbl = hashinit(NNULLNODECACHE, M_CACHE, &null_node_hash); |
| 101 | } |
| 102 | |
| 103 | /* |
| 104 | * Return a vnode_get'ed alias for lower vnode if already exists, else 0. |
| 105 | */ |
| 106 | static struct vnode * |
| 107 | null_node_find(mp, lowervp) |
| 108 | struct mount *mp; |
| 109 | struct vnode *lowervp; |
| 110 | { |
| 111 | struct proc *p = curproc; /* XXX */ |
| 112 | struct null_node_hashhead *hd; |
| 113 | struct null_node *a; |
| 114 | struct vnode *vp; |
| 115 | |
| 116 | /* |
| 117 | * Find hash base, and then search the (two-way) linked |
| 118 | * list looking for a null_node structure which is referencing |
| 119 | * the lower vnode. If found, the increment the null_node |
| 120 | * reference count (but NOT the lower vnode's vnode_get counter). |
| 121 | */ |
| 122 | hd = NULL_NHASH(lowervp); |
| 123 | loop: |
| 124 | for (a = hd->lh_first; a != 0; a = a->null_hash.le_next) { |
| 125 | if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) { |
| 126 | vp = NULLTOV(a); |
| 127 | |
| 128 | if (vnode_get(vp)) { |
| 129 | printf ("null_node_find: vget failed.\n"); |
| 130 | goto loop; |
| 131 | }; |
| 132 | return (vp); |
| 133 | } |
| 134 | } |
| 135 | |
| 136 | return NULL; |
| 137 | } |
| 138 | |
| 139 | |
| 140 | /* |
| 141 | * Make a new null_node node. |
| 142 | * Vp is the alias vnode, lofsvp is the lower vnode. |
| 143 | * Maintain a reference to (lowervp). |
| 144 | */ |
| 145 | static int |
| 146 | null_node_alloc(mp, lowervp, vpp) |
| 147 | struct mount *mp; |
| 148 | struct vnode *lowervp; |
| 149 | struct vnode **vpp; |
| 150 | { |
| 151 | struct null_node_hashhead *hd; |
| 152 | struct null_node *xp; |
| 153 | struct vnode *othervp, *vp; |
| 154 | int error; |
| 155 | |
| 156 | MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK); |
| 157 | if (error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp)) { |
| 158 | FREE(xp, M_TEMP); |
| 159 | return (error); |
| 160 | } |
| 161 | vp = *vpp; |
| 162 | |
| 163 | vp->v_type = lowervp->v_type; |
| 164 | xp->null_vnode = vp; |
| 165 | vp->v_data = xp; |
| 166 | xp->null_lowervp = lowervp; |
| 167 | /* |
| 168 | * Before we insert our new node onto the hash chains, |
| 169 | * check to see if someone else has beaten us to it. |
| 170 | */ |
| 171 | if (othervp = null_node_find(lowervp)) { |
| 172 | FREE(xp, M_TEMP); |
| 173 | vp->v_type = VBAD; /* node is discarded */ |
| 174 | vp->v_usecount = 0; /* XXX */ |
| 175 | vp->v_data = 0; /* prevent access to freed data */ |
| 176 | *vpp = othervp; |
| 177 | return 0; |
| 178 | }; |
| 179 | if (vp->v_type == VREG) |
| 180 | ubc_info_init(vp); |
| 181 | vnode_get(lowervp); /* Extra vnode_get will be vnode_put'd in null_node_create */ |
| 182 | hd = NULL_NHASH(lowervp); |
| 183 | LIST_INSERT_HEAD(hd, xp, null_hash); |
| 184 | return 0; |
| 185 | } |
| 186 | |
| 187 | |
| 188 | /* |
| 189 | * Try to find an existing null_node vnode refering |
| 190 | * to it, otherwise make a new null_node vnode which |
| 191 | * contains a reference to the lower vnode. |
| 192 | */ |
| 193 | int |
| 194 | null_node_create(mp, lowervp, newvpp) |
| 195 | struct mount *mp; |
| 196 | struct vnode *lowervp; |
| 197 | struct vnode **newvpp; |
| 198 | { |
| 199 | struct vnode *aliasvp; |
| 200 | |
| 201 | if (aliasvp = null_node_find(mp, lowervp)) { |
| 202 | /* |
| 203 | * null_node_find has taken another reference |
| 204 | * to the alias vnode. |
| 205 | */ |
| 206 | #ifdef NULLFS_DIAGNOSTIC |
| 207 | vprint("null_node_create: exists", NULLTOV(ap)); |
| 208 | #endif |
| 209 | /* vnode_get(aliasvp); --- done in null_node_find */ |
| 210 | } else { |
| 211 | int error; |
| 212 | |
| 213 | /* |
| 214 | * Get new vnode. |
| 215 | */ |
| 216 | #ifdef NULLFS_DIAGNOSTIC |
| 217 | printf("null_node_create: create new alias vnode\n"); |
| 218 | #endif |
| 219 | |
| 220 | /* |
| 221 | * Make new vnode reference the null_node. |
| 222 | */ |
| 223 | if (error = null_node_alloc(mp, lowervp, &aliasvp)) |
| 224 | return error; |
| 225 | |
| 226 | /* |
| 227 | * aliasvp is already vnode_get'd by getnewvnode() |
| 228 | */ |
| 229 | } |
| 230 | |
| 231 | vnode_put(lowervp); |
| 232 | |
| 233 | #if DIAGNOSTIC |
| 234 | if (lowervp->v_usecount < 1) { |
| 235 | /* Should never happen... */ |
| 236 | vprint ("null_node_create: alias ", aliasvp); |
| 237 | vprint ("null_node_create: lower ", lowervp); |
| 238 | panic ("null_node_create: lower has 0 usecount."); |
| 239 | }; |
| 240 | #endif |
| 241 | |
| 242 | #ifdef NULLFS_DIAGNOSTIC |
| 243 | vprint("null_node_create: alias", aliasvp); |
| 244 | vprint("null_node_create: lower", lowervp); |
| 245 | #endif |
| 246 | |
| 247 | *newvpp = aliasvp; |
| 248 | return (0); |
| 249 | } |
| 250 | #ifdef NULLFS_DIAGNOSTIC |
| 251 | struct vnode * |
| 252 | null_checkvp(vp, fil, lno) |
| 253 | struct vnode *vp; |
| 254 | char *fil; |
| 255 | int lno; |
| 256 | { |
| 257 | struct null_node *a = VTONULL(vp); |
| 258 | #ifdef notyet |
| 259 | /* |
| 260 | * Can't do this check because vnop_reclaim runs |
| 261 | * with a funny vop vector. |
| 262 | */ |
| 263 | if (vp->v_op != null_vnodeop_p) { |
| 264 | printf ("null_checkvp: on non-null-node\n"); |
| 265 | while (null_checkvp_barrier) /*WAIT*/ ; |
| 266 | panic("null_checkvp"); |
| 267 | }; |
| 268 | #endif |
| 269 | if (a->null_lowervp == NULL) { |
| 270 | /* Should never happen */ |
| 271 | int i; u_long *p; |
| 272 | printf("vp = %x, ZERO ptr\n", vp); |
| 273 | for (p = (u_long *) a, i = 0; i < 8; i++) |
| 274 | printf(" %x", p[i]); |
| 275 | printf("\n"); |
| 276 | /* wait for debugger */ |
| 277 | while (null_checkvp_barrier) /*WAIT*/ ; |
| 278 | panic("null_checkvp"); |
| 279 | } |
| 280 | if (a->null_lowervp->v_usecount < 1) { |
| 281 | int i; u_long *p; |
| 282 | printf("vp = %x, unref'ed lowervp\n", vp); |
| 283 | for (p = (u_long *) a, i = 0; i < 8; i++) |
| 284 | printf(" %x", p[i]); |
| 285 | printf("\n"); |
| 286 | /* wait for debugger */ |
| 287 | while (null_checkvp_barrier) /*WAIT*/ ; |
| 288 | panic ("null with unref'ed lowervp"); |
| 289 | }; |
| 290 | #ifdef notyet |
| 291 | printf("null %x/%d -> %x/%d [%s, %d]\n", |
| 292 | NULLTOV(a), NULLTOV(a)->v_usecount, |
| 293 | a->null_lowervp, a->null_lowervp->v_usecount, |
| 294 | fil, lno); |
| 295 | #endif |
| 296 | return a->null_lowervp; |
| 297 | } |
| 298 | #endif |