bsd/hfs/hfs_chash.c

   1 /*
   2  * Copyright (c) 2002 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
  23 /*
  24  * Copyright (c) 1982, 1986, 1989, 1991, 1993, 1995
  25  *      The Regents of the University of California.  All rights reserved.
  26  *
  27  * Redistribution and use in source and binary forms, with or without
  28  * modification, are permitted provided that the following conditions
  29  * are met:
  30  * 1. Redistributions of source code must retain the above copyright
  31  *        notice, this list of conditions and the following disclaimer.
  32  * 2. Redistributions in binary form must reproduce the above copyright
  33  *        notice, this list of conditions and the following disclaimer in the
  34  *        documentation and/or other materials provided with the distribution.
  35  * 3. All advertising materials mentioning features or use of this software
  36  *        must display the following acknowledgement:
  37  *      This product includes software developed by the University of
  38  *      California, Berkeley and its contributors.
  39  * 4. Neither the name of the University nor the names of its contributors
  40  *        may be used to endorse or promote products derived from this software
  41  *        without specific prior written permission.
  42  *
  43  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  44  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  45  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  46  * ARE DISCLAIMED.      IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  47  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  48  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  49  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  50  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  51  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  52  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  53  * SUCH DAMAGE.
  54  *
  55  *      @(#)hfs_chash.c
  56  *      derived from @(#)ufs_ihash.c    8.7 (Berkeley) 5/17/95
  57  */
  58
  59 #include <sys/param.h>
  60 #include <sys/systm.h>
  61 #include <sys/vnode.h>
  62 #include <sys/malloc.h>
  63 #include <sys/proc.h>
  64 #include <sys/queue.h>
  65
  66 #include "hfs_cnode.h"
  67
  68
  69 /*
  70  * Structures associated with cnode caching.
  71  */
  72 LIST_HEAD(cnodehashhead, cnode) *cnodehashtbl;
  73 u_long  cnodehash;              /* size of hash table - 1 */
  74 #define CNODEHASH(device, inum) (&cnodehashtbl[((device) + (inum)) & cnodehash])
  75 struct slock hfs_chash_slock;
  76
  77 /*
  78  * Initialize cnode hash table.
  79  */
  80 __private_extern__
  81 void
  82 hfs_chashinit()
  83 {
  84         cnodehashtbl = hashinit(desiredvnodes, M_HFSMNT, &cnodehash);
  85         simple_lock_init(&hfs_chash_slock);
  86 }
  87
  88
  89 /*
  90  * Use the device, inum pair to find the incore cnode.
  91  *
  92  * If it is in core, but locked, wait for it.
  93  *
  94  * If the requested vnode (fork) is not available, then
  95  * take a reference on the other vnode (fork) so that
  96  * the upcoming getnewvnode can not aquire it.
  97  */
  98 __private_extern__
  99 struct cnode *
 100 hfs_chashget(dev_t dev, ino_t inum, int wantrsrc,
 101                 struct vnode **vpp, struct vnode **rvpp)
 102 {
 103         struct proc *p = current_proc();
 104         struct cnode *cp;
 105         struct vnode *vp;
 106         int error;
 107
 108         *vpp = NULLVP;
 109         *rvpp = NULLVP;
 110         /*
 111          * Go through the hash list
 112          * If a cnode is in the process of being cleaned out or being
 113          * allocated, wait for it to be finished and then try again.
 114          */
 115 loop:
 116         simple_lock(&hfs_chash_slock);
 117         for (cp = CNODEHASH(dev, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 118                 if ((cp->c_fileid != inum) || (cp->c_dev != dev))
 119                         continue;
 120                 if (ISSET(cp->c_flag, C_ALLOC)) {
 121                         /*
 122                          * cnode is being created. Wait for it to finish.
 123                          */
 124                         SET(cp->c_flag, C_WALLOC);
 125                         simple_unlock(&hfs_chash_slock);
 126                         (void) tsleep((caddr_t)cp, PINOD, "hfs_chashget-1", 0);
 127                         goto loop;
 128                 }
 129                 if (ISSET(cp->c_flag, C_TRANSIT)) {
 130                         /*
 131                          * cnode is getting reclaimed wait for
 132                          * the operation to complete and return
 133                          * error
 134                          */
 135                         SET(cp->c_flag, C_WTRANSIT);
 136                         simple_unlock(&hfs_chash_slock);
 137                         (void)tsleep((caddr_t)cp, PINOD, "hfs_chashget-2", 0);
 138                         goto loop;
 139                 }
 140                 if (cp->c_flag & C_NOEXISTS)
 141                         continue;
 142
 143                 /*
 144                  * Try getting the desired vnode first.  If
 145                  * it isn't available then take a reference
 146                  * on the other vnode.
 147                  */
 148                 vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
 149                 if (vp == NULLVP)
 150                         vp = wantrsrc ? cp->c_vp : cp->c_rsrc_vp;
 151                 if (vp == NULLVP)
 152                         panic("hfs_chashget: orphaned cnode in hash");
 153
 154                 simple_lock(&vp->v_interlock);
 155                 simple_unlock(&hfs_chash_slock);
 156                 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, p))
 157                         goto loop;
 158                 else if (cp->c_flag & C_NOEXISTS) {
 159                         /*
 160                          * While we were blocked the cnode got deleted.
 161                          */
 162                         vput(vp);
 163                         goto loop;
 164                 }
 165
 166                 if (VNODE_IS_RSRC(vp))
 167                         *rvpp = vp;
 168                 else
 169                         *vpp = vp;
 170                 /*
 171                  * Note that vget can block before aquiring the
 172                  * cnode lock.  So we need to check if the vnode
 173                  * we wanted was created while we blocked.
 174                  */
 175                 if (wantrsrc && *rvpp == NULL && cp->c_rsrc_vp) {
 176                         error = vget(cp->c_rsrc_vp, 0, p);
 177                         vput(*vpp);     /* ref no longer needed */
 178                         *vpp = NULL;
 179                         if (error)
 180                                 goto loop;
 181                         *rvpp = cp->c_rsrc_vp;
 182
 183                 } else if (!wantrsrc && *vpp == NULL && cp->c_vp) {
 184                         error = vget(cp->c_vp, 0, p);
 185                         vput(*rvpp);    /* ref no longer needed */
 186                         *rvpp = NULL;
 187                         if (error)
 188                                 goto loop;
 189                         *vpp = cp->c_vp;
 190                 }
 191                 return (cp);
 192         }
 193         simple_unlock(&hfs_chash_slock);
 194         return (NULL);
 195 }
 196
 197
 198 /*
 199  * Insert a cnode into the hash table.
 200  */
 201 __private_extern__
 202 void
 203 hfs_chashinsert(struct cnode *cp)
 204 {
 205         if (cp->c_fileid == 0)
 206                 panic("hfs_chashinsert: trying to insert file id 0");
 207         simple_lock(&hfs_chash_slock);
 208         LIST_INSERT_HEAD(CNODEHASH(cp->c_dev, cp->c_fileid), cp, c_hash);
 209         simple_unlock(&hfs_chash_slock);
 210 }
 211
 212
 213 /*
 214  * Remove a cnode from the hash table.
 215  */
 216 __private_extern__
 217 void
 218 hfs_chashremove(struct cnode *cp)
 219 {
 220         simple_lock(&hfs_chash_slock);
 221         LIST_REMOVE(cp, c_hash);
 222         cp->c_hash.le_next = NULL;
 223         cp->c_hash.le_prev = NULL;
 224         simple_unlock(&hfs_chash_slock);
 225 }
 226