sys/vfs/gnu/ext2fs/ext2_ihash.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1989, 1991, 1993, 1995
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)ufs_ihash.c      8.7 (Berkeley) 5/17/95
  34  * $FreeBSD: src/sys/ufs/ufs/ufs_ihash.c,v 1.20 1999/08/28 00:52:29 peter Exp $
  35  * $DragonFly: src/sys/vfs/gnu/ext2fs/ext2_ihash.c,v 1.5 2006/10/14 16:26:38 dillon Exp $
  36  */
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/kernel.h>
  41 #include <sys/lock.h>
  42 #include <sys/vnode.h>
  43 #include <sys/malloc.h>
  44 #include <sys/proc.h>
  45
  46 #include "quota.h"
  47 #include "dinode.h"
  48 #include "inode.h"
  49 #include "ext2_extern.h"
  50
  51 static MALLOC_DEFINE(M_EXT2IHASH, "EXT2 ihash", "EXT2 Inode hash tables");
  52 /*
  53  * Structures associated with inode cacheing.
  54  */
  55 static struct inode **ext2_ihashtbl;
  56 static u_long   ext2_ihash;             /* size of hash table - 1 */
  57 static struct lwkt_token ext2_ihash_token;
  58
  59 #define INOHASH(device, inum)   (&ext2_ihashtbl[(minor(device) + (inum)) & ext2_ihash])
  60
  61 /*
  62  * Initialize inode hash table.
  63  */
  64 void
  65 ext2_ihashinit(void)
  66 {
  67         ext2_ihash = 16;
  68         while (ext2_ihash < desiredvnodes)
  69                 ext2_ihash <<= 1;
  70         ext2_ihashtbl = kmalloc(sizeof(void *) * ext2_ihash, M_EXT2IHASH, M_WAITOK|M_ZERO);
  71         --ext2_ihash;
  72         lwkt_token_init(&ext2_ihash_token, "ext2ihash");
  73 }
  74
  75 int
  76 ext2_uninit(struct vfsconf *vfc)
  77 {
  78     lwkt_gettoken(&ext2_ihash_token);
  79     if (ext2_ihashtbl)
  80                 kfree(ext2_ihashtbl, M_EXT2IHASH);
  81     lwkt_reltoken(&ext2_ihash_token);
  82
  83     return (0);
  84 }
  85 /*
  86  * Use the device/inum pair to find the incore inode, and return a pointer
  87  * to it. If it is in core, return it, even if it is locked.
  88  */
  89 struct vnode *
  90 ext2_ihashlookup(cdev_t dev, ino_t inum)
  91 {
  92         struct inode *ip;
  93
  94         lwkt_gettoken(&ext2_ihash_token);
  95         for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
  96                 if (inum == ip->i_number && dev == ip->i_dev)
  97                         break;
  98         }
  99         lwkt_reltoken(&ext2_ihash_token);
 100         if (ip)
 101                 return (ITOV(ip));
 102         return (NULLVP);
 103 }
 104
 105 /*
 106  * Use the device/inum pair to find the incore inode, and return a pointer
 107  * to it. If it is in core, but locked, wait for it.
 108  *
 109  * Note that the serializing tokens do not prevent other processes from
 110  * playing with the data structure being protected while we are blocked.
 111  * They do protect us from preemptive interrupts which might try to
 112  * play with the protected data structure.
 113  */
 114 struct vnode *
 115 ext2_ihashget(cdev_t dev, ino_t inum)
 116 {
 117         struct inode *ip;
 118         struct vnode *vp;
 119
 120         lwkt_gettoken(&ext2_ihash_token);
 121 loop:
 122         for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
 123                 if (inum != ip->i_number || dev != ip->i_dev)
 124                         continue;
 125                 vp = ITOV(ip);
 126                 if (vget(vp, LK_EXCLUSIVE))
 127                         goto loop;
 128                 /*
 129                  * We must check to see if the inode has been ripped
 130                  * out from under us after blocking.
 131                  */
 132                 for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
 133                         if (inum == ip->i_number && dev == ip->i_dev)
 134                                 break;
 135                 }
 136                 if (ip == NULL || ITOV(ip) != vp) {
 137                         vput(vp);
 138                         goto loop;
 139                 }
 140                 lwkt_reltoken(&ext2_ihash_token);
 141                 return (vp);
 142         }
 143         lwkt_reltoken(&ext2_ihash_token);
 144         return (NULL);
 145 }
 146
 147 /*
 148  * Check to see if an inode is in the hash table.  This is used to interlock
 149  * file free operations to ensure that the vnode is not reused due to a
 150  * reallocate of its inode number before we have had a chance to recycle it.
 151  */
 152 int
 153 ext2_ihashcheck(cdev_t dev, ino_t inum)
 154 {
 155         struct inode *ip;
 156
 157         lwkt_gettoken(&ext2_ihash_token);
 158         for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
 159                 if (inum == ip->i_number && dev == ip->i_dev)
 160                         break;
 161         }
 162         lwkt_reltoken(&ext2_ihash_token);
 163         return(ip ? 1 : 0);
 164 }
 165
 166 /*
 167  * Insert the inode into the hash table, and return it locked.
 168  */
 169 int
 170 ext2_ihashins(struct inode *ip)
 171 {
 172         struct inode **ipp;
 173         struct inode *iq;
 174
 175         KKASSERT((ip->i_flag & IN_HASHED) == 0);
 176         lwkt_gettoken(&ext2_ihash_token);
 177         ipp = INOHASH(ip->i_dev, ip->i_number);
 178         while ((iq = *ipp) != NULL) {
 179                 if (ip->i_dev == iq->i_dev && ip->i_number == iq->i_number) {
 180                         lwkt_reltoken(&ext2_ihash_token);
 181                         return(EBUSY);
 182                 }
 183                 ipp = &iq->i_next;
 184         }
 185         ip->i_next = NULL;
 186         *ipp = ip;
 187         ip->i_flag |= IN_HASHED;
 188         lwkt_reltoken(&ext2_ihash_token);
 189         return(0);
 190 }
 191
 192 /*
 193  * Remove the inode from the hash table.
 194  */
 195 void
 196 ext2_ihashrem(struct inode *ip)
 197 {
 198         struct inode **ipp;
 199         struct inode *iq;
 200
 201         lwkt_gettoken(&ext2_ihash_token);
 202         if (ip->i_flag & IN_HASHED) {
 203                 ipp = INOHASH(ip->i_dev, ip->i_number);
 204                 while ((iq = *ipp) != NULL) {
 205                         if (ip == iq)
 206                                 break;
 207                         ipp = &iq->i_next;
 208                 }
 209                 KKASSERT(ip == iq);
 210                 *ipp = ip->i_next;
 211                 ip->i_next = NULL;
 212                 ip->i_flag &= ~IN_HASHED;
 213         }
 214         lwkt_reltoken(&ext2_ihash_token);
 215 }
 216