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  * $FreeBSD$
   39  */
   40 
   41 #include <sys/param.h>
   42 
   43 #include <sys/proc.h>
   44 #include <sys/sdt.h>
   45 #include <sys/systm.h>
   46 #include <sys/bio.h>
   47 #include <sys/buf.h>
   48 #include <sys/lock.h>
   49 #include <sys/ucred.h>
   50 #include <sys/vnode.h>
   51 
   52 #include <fs/ext2fs/fs.h>
   53 #include <fs/ext2fs/inode.h>
   54 #include <fs/ext2fs/ext2fs.h>
   55 #include <fs/ext2fs/ext2_extern.h>
   56 #include <fs/ext2fs/fs.h>
   57 #include <fs/ext2fs/ext2_extents.h>
   58 #include <fs/ext2fs/ext2_mount.h>
   59 #include <fs/ext2fs/ext2_dinode.h>
   60 
   61 /*
   62  * Return buffer with the contents of block "offset" from the beginning of
   63  * directory "ip".  If "res" is non-zero, fill it in with a pointer to the
   64  * remaining space in the directory.
   65  */
   66 int
   67 ext2_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
   68 {
   69         struct inode *ip;
   70         struct m_ext2fs *fs;
   71         struct buf *bp;
   72         e2fs_lbn_t lbn;
   73         int error, bsize;
   74 
   75         ip = VTOI(vp);
   76         fs = ip->i_e2fs;
   77         lbn = lblkno(fs, offset);
   78         bsize = blksize(fs, ip, lbn);
   79 
   80         if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
   81                 brelse(bp);
   82                 return (error);
   83         }
   84         error = ext2_dir_blk_csum_verify(ip, bp);
   85         if (error != 0) {
   86                 brelse(bp);
   87                 return (error);
   88         }
   89         if (res)
   90                 *res = (char *)bp->b_data + blkoff(fs, offset);
   91 
   92         *bpp = bp;
   93 
   94         return (0);
   95 }
   96 
   97 /*
   98  * Update the cluster map because of an allocation of free like ffs.
   99  *
  100  * Cnt == 1 means free; cnt == -1 means allocating.
  101  */
  102 void
  103 ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, e4fs_daddr_t bno, int cnt)
  104 {
  105         int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
  106         int32_t *lp;
  107         e4fs_daddr_t start, end, loc, forw, back;
  108         int bit, i;
  109 
  110         /* Initialize the cluster summary array. */
  111         if (fs->e2fs_clustersum[cg].cs_init == 0) {
  112                 int run = 0;
  113 
  114                 bit = 1;
  115                 loc = 0;
  116 
  117                 for (i = 0; i < fs->e2fs->e2fs_fpg; i++) {
  118                         if ((bbp[loc] & bit) == 0)
  119                                 run++;
  120                         else if (run != 0) {
  121                                 if (run > fs->e2fs_contigsumsize)
  122                                         run = fs->e2fs_contigsumsize;
  123                                 sump[run]++;
  124                                 run = 0;
  125                         }
  126                         if ((i & (NBBY - 1)) != (NBBY - 1))
  127                                 bit <<= 1;
  128                         else {
  129                                 loc++;
  130                                 bit = 1;
  131                         }
  132                 }
  133                 if (run != 0) {
  134                         if (run > fs->e2fs_contigsumsize)
  135                                 run = fs->e2fs_contigsumsize;
  136                         sump[run]++;
  137                 }
  138                 fs->e2fs_clustersum[cg].cs_init = 1;
  139         }
  140 
  141         if (fs->e2fs_contigsumsize <= 0)
  142                 return;
  143 
  144         /* Find the size of the cluster going forward. */
  145         start = bno + 1;
  146         end = start + fs->e2fs_contigsumsize;
  147         if (end > fs->e2fs->e2fs_fpg)
  148                 end = fs->e2fs->e2fs_fpg;
  149         loc = start / NBBY;
  150         bit = 1 << (start % NBBY);
  151         for (i = start; i < end; i++) {
  152                 if ((bbp[loc] & bit) != 0)
  153                         break;
  154                 if ((i & (NBBY - 1)) != (NBBY - 1))
  155                         bit <<= 1;
  156                 else {
  157                         loc++;
  158                         bit = 1;
  159                 }
  160         }
  161         forw = i - start;
  162 
  163         /* Find the size of the cluster going backward. */
  164         start = bno - 1;
  165         end = start - fs->e2fs_contigsumsize;
  166         if (end < 0)
  167                 end = -1;
  168         loc = start / NBBY;
  169         bit = 1 << (start % NBBY);
  170         for (i = start; i > end; i--) {
  171                 if ((bbp[loc] & bit) != 0)
  172                         break;
  173                 if ((i & (NBBY - 1)) != 0)
  174                         bit >>= 1;
  175                 else {
  176                         loc--;
  177                         bit = 1 << (NBBY - 1);
  178                 }
  179         }
  180         back = start - i;
  181 
  182         /*
  183          * Account for old cluster and the possibly new forward and
  184          * back clusters.
  185          */
  186         i = back + forw + 1;
  187         if (i > fs->e2fs_contigsumsize)
  188                 i = fs->e2fs_contigsumsize;
  189         sump[i] += cnt;
  190         if (back > 0)
  191                 sump[back] -= cnt;
  192         if (forw > 0)
  193                 sump[forw] -= cnt;
  194 
  195         /* Update cluster summary information. */
  196         lp = &sump[fs->e2fs_contigsumsize];
  197         for (i = fs->e2fs_contigsumsize; i > 0; i--)
  198                 if (*lp-- > 0)
  199                         break;
  200         fs->e2fs_maxcluster[cg] = i;
  201 }

Cache object: 9c1f8f914cef797babb4b05070c73a00


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