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Annotation of kernel/bsd/hfs/hfs_vhash.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* Copyright (c) 1998 Apple Computer, Inc. All Rights Reserved */
        !            26: /*
        !            27:  * Copyright (c) 1982, 1986, 1989, 1991, 1993, 1995
        !            28:  *     The Regents of the University of California.  All rights reserved.
        !            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:  *     @(#)hfs_vhash.c
        !            59:  *     derived from @(#)ufs_ihash.c    8.7 (Berkeley) 5/17/95
        !            60:  */
        !            61: 
        !            62: #include <sys/param.h>
        !            63: #include <mach/machine/vm_types.h>
        !            64: #include <sys/vnode.h>
        !            65: #include <sys/malloc.h>
        !            66: #include <sys/proc.h>
        !            67: #include <sys/systm.h>
        !            68: 
        !            69: #include "hfs.h"
        !            70: 
        !            71: #include <libkern/libkern.h>
        !            72: #include <mach/machine/simple_lock.h>
        !            73: 
        !            74: /*
        !            75:  * Structures associated with hfsnode cacheing.
        !            76:  */
        !            77: LIST_HEAD(vhashhead, hfsnode) *vhashtbl;
        !            78: u_long vhash;          /* size of hash table - 1 */
        !            79: #define        HFSNODEHASH(device, nodeID, forkType)   (&vhashtbl[((device) + ((nodeID)<<2) + (forkType)) & vhash])
        !            80: struct slock hfs_vhash_slock;
        !            81: 
        !            82: /*
        !            83:  * Initialize hfsnode hash table.
        !            84:  */
        !            85: void
        !            86: hfs_vhashinit()
        !            87: {
        !            88: 
        !            89:     vhashtbl = hashinit(desiredvnodes, M_HFSMNT, &vhash);
        !            90:        simple_lock_init(&hfs_vhash_slock);
        !            91: }
        !            92: 
        !            93: /*
        !            94:  * Use the device/dirID pair to find the incore hfsnode, and return a pointer
        !            95:  * to it. If it is in core, return it, even if it is locked.
        !            96:  */
        !            97: struct vnode *
        !            98: hfs_vhashlookup(dev, nodeID, forkType)
        !            99:        dev_t           dev;
        !           100:     UInt32             nodeID;
        !           101: UInt8  forkType;
        !           102: {
        !           103:        struct hfsnode *hp;
        !           104: 
        !           105:        simple_lock(&hfs_vhash_slock);
        !           106:     for (hp = HFSNODEHASH(dev, nodeID, forkType)->lh_first; hp; hp = hp->h_hash.le_next)
        !           107:        if ((H_FILEID(hp) == nodeID) && (hp->h_dev == dev) && (H_FORKTYPE(hp) == forkType))
        !           108:                        break;
        !           109:        simple_unlock(&hfs_vhash_slock);
        !           110: 
        !           111:        if (hp)
        !           112:                return (HTOV(hp));
        !           113:        return (NULLVP);
        !           114: }
        !           115: 
        !           116: /*
        !           117:  * Use the device/dirID pair to find the incore hfsnode, and return a pointer
        !           118:  * to it. If it is in core, but locked, wait for it.
        !           119:  */
        !           120: struct vnode *
        !           121: hfs_vhashget(dev, nodeID, forkType)
        !           122:     dev_t dev;
        !           123:     UInt32 nodeID;
        !           124:        UInt8   forkType;
        !           125: {
        !           126:        struct proc *p = CURRENT_PROC;  /* XXX */
        !           127:        struct hfsnode *hp;
        !           128:        struct vnode *vp;
        !           129: 
        !           130: loop:
        !           131:        simple_lock(&hfs_vhash_slock);
        !           132:     for (hp = HFSNODEHASH(dev, nodeID, forkType)->lh_first; hp; hp = hp->h_hash.le_next) {
        !           133:        if ((H_FILEID(hp) == nodeID) && (hp->h_dev == dev) && (H_FORKTYPE(hp) == forkType)) {
        !           134:                        vp = HTOV(hp);
        !           135:                        simple_lock(&vp->v_interlock);
        !           136:                        simple_unlock(&hfs_vhash_slock);
        !           137:                        if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, p))
        !           138:                                goto loop;
        !           139:                        return (vp);
        !           140:                }
        !           141:        }
        !           142:        simple_unlock(&hfs_vhash_slock);
        !           143:        return (NULL);
        !           144: }
        !           145: 
        !           146: /*
        !           147: * Lock the hfsnode and insert the hfsnode into the hash table, and return it locked.
        !           148:  */
        !           149: void
        !           150: hfs_vhashins(hp)
        !           151:        struct hfsnode *hp;
        !           152: {
        !           153:        struct vhashhead *ipp;
        !           154: 
        !           155:     lockmgr(&hp->h_lock, LK_EXCLUSIVE, (struct slock *)0, CURRENT_PROC);
        !           156: 
        !           157:        simple_lock(&hfs_vhash_slock);
        !           158:     ipp = HFSNODEHASH(hp->h_dev, H_FILEID(hp), H_FORKTYPE(hp));
        !           159:        LIST_INSERT_HEAD(ipp, hp, h_hash);
        !           160:        simple_unlock(&hfs_vhash_slock);
        !           161: }
        !           162: 
        !           163: /*
        !           164:  * Insert a locked hfsnode into the hash table.
        !           165:  */
        !           166: void
        !           167: hfs_vhashinslocked(hp)
        !           168:        struct hfsnode *hp;
        !           169: {
        !           170:        struct vhashhead *ipp;
        !           171: 
        !           172:        simple_lock(&hfs_vhash_slock);
        !           173:     ipp = HFSNODEHASH(hp->h_dev, H_FILEID(hp), H_FORKTYPE(hp));
        !           174:        LIST_INSERT_HEAD(ipp, hp, h_hash);
        !           175:        simple_unlock(&hfs_vhash_slock);
        !           176: }
        !           177: 
        !           178: /*
        !           179:  * Remove the hfsnode from the hash table.
        !           180:  */
        !           181: void
        !           182: hfs_vhashrem(hp)
        !           183:        struct hfsnode *hp;
        !           184: {
        !           185: 
        !           186:        simple_lock(&hfs_vhash_slock);
        !           187:     LIST_REMOVE(hp, h_hash);
        !           188: #if DIAGNOSTIC
        !           189:        hp->h_hash.le_next = NULL;
        !           190:        hp->h_hash.le_prev = NULL;
        !           191: #endif
        !           192:        simple_unlock(&hfs_vhash_slock);
        !           193: }

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