The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_subr.c

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    1 /*-
    2  *  modified for Lites 1.1
    3  *
    4  *  Aug 1995, Godmar Back (gback@cs.utah.edu)
    5  *  University of Utah, Department of Computer Science
    6  */
    7 /*-
    8  * SPDX-License-Identifier: BSD-3-Clause
    9  *
   10  * Copyright (c) 1982, 1986, 1989, 1993
   11  *      The Regents of the University of California.  All rights reserved.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 3. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      @(#)ffs_subr.c  8.2 (Berkeley) 9/21/93
   38  * $FreeBSD: releng/12.0/sys/fs/ext2fs/ext2_subr.c 333584 2018-05-13 19:19:10Z fsu $
   39  */
   40 
   41 #include <sys/param.h>
   42 
   43 #include <sys/proc.h>
   44 #include <sys/systm.h>
   45 #include <sys/bio.h>
   46 #include <sys/buf.h>
   47 #include <sys/lock.h>
   48 #include <sys/ucred.h>
   49 #include <sys/vnode.h>
   50 
   51 #include <fs/ext2fs/fs.h>
   52 #include <fs/ext2fs/inode.h>
   53 #include <fs/ext2fs/ext2fs.h>
   54 #include <fs/ext2fs/ext2_extern.h>
   55 #include <fs/ext2fs/fs.h>
   56 #include <fs/ext2fs/ext2_extents.h>
   57 #include <fs/ext2fs/ext2_mount.h>
   58 #include <fs/ext2fs/ext2_dinode.h>
   59 
   60 /*
   61  * Return buffer with the contents of block "offset" from the beginning of
   62  * directory "ip".  If "res" is non-zero, fill it in with a pointer to the
   63  * remaining space in the directory.
   64  */
   65 int
   66 ext2_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
   67 {
   68         struct inode *ip;
   69         struct m_ext2fs *fs;
   70         struct buf *bp;
   71         e2fs_lbn_t lbn;
   72         int error, bsize;
   73 
   74         ip = VTOI(vp);
   75         fs = ip->i_e2fs;
   76         lbn = lblkno(fs, offset);
   77         bsize = blksize(fs, ip, lbn);
   78 
   79         if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
   80                 brelse(bp);
   81                 return (error);
   82         }
   83         error = ext2_dir_blk_csum_verify(ip, bp);
   84         if (error != 0) {
   85                 brelse(bp);
   86                 return (error);
   87         }
   88         if (res)
   89                 *res = (char *)bp->b_data + blkoff(fs, offset);
   90 
   91         *bpp = bp;
   92 
   93         return (0);
   94 }
   95 
   96 /*
   97  * Update the cluster map because of an allocation of free like ffs.
   98  *
   99  * Cnt == 1 means free; cnt == -1 means allocating.
  100  */
  101 void
  102 ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, e4fs_daddr_t bno, int cnt)
  103 {
  104         int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
  105         int32_t *lp;
  106         e4fs_daddr_t start, end, loc, forw, back;
  107         int bit, i;
  108 
  109         /* Initialize the cluster summary array. */
  110         if (fs->e2fs_clustersum[cg].cs_init == 0) {
  111                 int run = 0;
  112 
  113                 bit = 1;
  114                 loc = 0;
  115 
  116                 for (i = 0; i < fs->e2fs->e2fs_fpg; i++) {
  117                         if ((bbp[loc] & bit) == 0)
  118                                 run++;
  119                         else if (run != 0) {
  120                                 if (run > fs->e2fs_contigsumsize)
  121                                         run = fs->e2fs_contigsumsize;
  122                                 sump[run]++;
  123                                 run = 0;
  124                         }
  125                         if ((i & (NBBY - 1)) != (NBBY - 1))
  126                                 bit <<= 1;
  127                         else {
  128                                 loc++;
  129                                 bit = 1;
  130                         }
  131                 }
  132                 if (run != 0) {
  133                         if (run > fs->e2fs_contigsumsize)
  134                                 run = fs->e2fs_contigsumsize;
  135                         sump[run]++;
  136                 }
  137                 fs->e2fs_clustersum[cg].cs_init = 1;
  138         }
  139 
  140         if (fs->e2fs_contigsumsize <= 0)
  141                 return;
  142 
  143         /* Find the size of the cluster going forward. */
  144         start = bno + 1;
  145         end = start + fs->e2fs_contigsumsize;
  146         if (end > fs->e2fs->e2fs_fpg)
  147                 end = fs->e2fs->e2fs_fpg;
  148         loc = start / NBBY;
  149         bit = 1 << (start % NBBY);
  150         for (i = start; i < end; i++) {
  151                 if ((bbp[loc] & bit) != 0)
  152                         break;
  153                 if ((i & (NBBY - 1)) != (NBBY - 1))
  154                         bit <<= 1;
  155                 else {
  156                         loc++;
  157                         bit = 1;
  158                 }
  159         }
  160         forw = i - start;
  161 
  162         /* Find the size of the cluster going backward. */
  163         start = bno - 1;
  164         end = start - fs->e2fs_contigsumsize;
  165         if (end < 0)
  166                 end = -1;
  167         loc = start / NBBY;
  168         bit = 1 << (start % NBBY);
  169         for (i = start; i > end; i--) {
  170                 if ((bbp[loc] & bit) != 0)
  171                         break;
  172                 if ((i & (NBBY - 1)) != 0)
  173                         bit >>= 1;
  174                 else {
  175                         loc--;
  176                         bit = 1 << (NBBY - 1);
  177                 }
  178         }
  179         back = start - i;
  180 
  181         /*
  182          * Account for old cluster and the possibly new forward and
  183          * back clusters.
  184          */
  185         i = back + forw + 1;
  186         if (i > fs->e2fs_contigsumsize)
  187                 i = fs->e2fs_contigsumsize;
  188         sump[i] += cnt;
  189         if (back > 0)
  190                 sump[back] -= cnt;
  191         if (forw > 0)
  192                 sump[forw] -= cnt;
  193 
  194         /* Update cluster summary information. */
  195         lp = &sump[fs->e2fs_contigsumsize];
  196         for (i = fs->e2fs_contigsumsize; i > 0; i--)
  197                 if (*lp-- > 0)
  198                         break;
  199         fs->e2fs_maxcluster[cg] = i;
  200 }

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