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  * Copyright (c) 1982, 1986, 1989, 1993
    9  *      The Regents of the University of California.  All rights reserved.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)ffs_subr.c  8.2 (Berkeley) 9/21/93
   36  * $FreeBSD: releng/9.1/sys/fs/ext2fs/ext2_subr.c 229549 2012-01-05 01:35:01Z pfg $
   37  */
   38 
   39 #include <sys/param.h>
   40 
   41 #include <sys/proc.h>
   42 #include <sys/systm.h>
   43 #include <sys/bio.h>
   44 #include <sys/buf.h>
   45 #include <sys/lock.h>
   46 #include <sys/ucred.h>
   47 #include <sys/vnode.h>
   48 
   49 #include <fs/ext2fs/inode.h>
   50 #include <fs/ext2fs/ext2_extern.h>
   51 #include <fs/ext2fs/ext2fs.h>
   52 #include <fs/ext2fs/fs.h>
   53 
   54 #ifdef KDB
   55 #include <fs/ext2fs/ext2_mount.h>
   56 
   57 void    ext2_checkoverlap(struct buf *, struct inode *);
   58 #endif
   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(vp, offset, res, bpp)
   67         struct vnode *vp;
   68         off_t offset;
   69         char **res;
   70         struct buf **bpp;
   71 {
   72         struct inode *ip;
   73         struct m_ext2fs *fs;
   74         struct buf *bp;
   75         int32_t lbn;
   76         int bsize, error;
   77 
   78         ip = VTOI(vp);
   79         fs = ip->i_e2fs;
   80         lbn = lblkno(fs, offset);
   81         bsize = blksize(fs, ip, lbn);
   82 
   83         *bpp = NULL;
   84         if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
   85                 brelse(bp);
   86                 return (error);
   87         }
   88         if (res)
   89                 *res = (char *)bp->b_data + blkoff(fs, offset);
   90         *bpp = bp;
   91         return (0);
   92 }
   93 
   94 #ifdef KDB
   95 void
   96 ext2_checkoverlap(bp, ip)
   97         struct buf *bp;
   98         struct inode *ip;
   99 {
  100         struct buf *ebp, *ep;
  101         int32_t start, last;
  102         struct vnode *vp;
  103 
  104         ebp = &buf[nbuf];
  105         start = bp->b_blkno;
  106         last = start + btodb(bp->b_bcount) - 1;
  107         for (ep = buf; ep < ebp; ep++) {
  108                 if (ep == bp || (ep->b_flags & B_INVAL))
  109                         continue;
  110                 vp = ip->i_ump->um_devvp;
  111                 /* look for overlap */
  112                 if (ep->b_bcount == 0 || ep->b_blkno > last ||
  113                     ep->b_blkno + btodb(ep->b_bcount) <= start)
  114                         continue;
  115                 vprint("Disk overlap", vp);
  116                 (void)printf("\tstart %d, end %d overlap start %lld, end %ld\n",
  117                         start, last, (long long)ep->b_blkno,
  118                         (long)(ep->b_blkno + btodb(ep->b_bcount) - 1));
  119                 panic("Disk buffer overlap");
  120         }
  121 }
  122 #endif /* KDB */
  123 
  124 /*
  125  * Update the cluster map because of an allocation of free like ffs.
  126  *
  127  * Cnt == 1 means free; cnt == -1 means allocating.
  128  */
  129 void
  130 ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, daddr_t bno, int cnt)
  131 {
  132         int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
  133         int32_t *lp;
  134         int back, bit, end, forw, i, loc, start;
  135 
  136         /* Initialize the cluster summary array. */
  137         if (fs->e2fs_clustersum[cg].cs_init == 0) {
  138                 int run = 0;
  139                 bit = 1;
  140                 loc = 0;
  141 
  142                 for (i = 0; i < fs->e2fs->e2fs_fpg; i++) {
  143                         if ((bbp[loc] & bit) == 0)
  144                                 run++;
  145                         else if (run != 0) {
  146                                 if (run > fs->e2fs_contigsumsize)
  147                                         run = fs->e2fs_contigsumsize;
  148                                 sump[run]++;
  149                                 run = 0;
  150                         }
  151                         if ((i & (NBBY - 1)) != (NBBY - 1))
  152                                 bit <<= 1;
  153                         else {
  154                                 loc++;
  155                                 bit = 1;
  156                         }
  157                 }
  158                 if (run != 0) {
  159                         if (run > fs->e2fs_contigsumsize)
  160                                 run = fs->e2fs_contigsumsize;
  161                         sump[run]++;
  162                 }
  163                 fs->e2fs_clustersum[cg].cs_init = 1;
  164         }
  165 
  166         if (fs->e2fs_contigsumsize <= 0)
  167                 return;
  168 
  169         /* Find the size of the cluster going forward. */
  170         start = bno + 1;
  171         end = start + fs->e2fs_contigsumsize;
  172         if (end > fs->e2fs->e2fs_fpg)
  173                 end = fs->e2fs->e2fs_fpg;
  174         loc = start / NBBY;
  175         bit = 1 << (start % NBBY);
  176         for (i = start; i < end; i++) {
  177                 if ((bbp[loc] & bit) != 0)
  178                         break;
  179                 if ((i & (NBBY - 1)) != (NBBY - 1))
  180                         bit <<= 1;
  181                 else {
  182                         loc++;
  183                         bit = 1;
  184                 }
  185         }
  186         forw = i - start;
  187 
  188         /* Find the size of the cluster going backward. */
  189         start = bno - 1;
  190         end = start - fs->e2fs_contigsumsize;
  191         if (end < 0)
  192                 end = -1;
  193         loc = start / NBBY;
  194         bit = 1 << (start % NBBY);
  195         for (i = start; i > end; i--) {
  196                 if ((bbp[loc] & bit) != 0)
  197                         break;
  198                 if ((i & (NBBY - 1)) != 0)
  199                         bit >>= 1;
  200                 else {
  201                         loc--;
  202                         bit = 1 << (NBBY - 1);
  203                 }
  204         }
  205         back = start - i;
  206 
  207         /*
  208          * Account for old cluster and the possibly new forward and
  209          * back clusters.
  210          */
  211         i = back + forw + 1;
  212         if (i > fs->e2fs_contigsumsize)
  213                 i = fs->e2fs_contigsumsize;
  214         sump[i] += cnt;
  215         if (back > 0)
  216                 sump[back] -= cnt;
  217         if (forw > 0)
  218                 sump[forw] -= cnt;
  219 
  220         /* Update cluster summary information. */
  221         lp = &sump[fs->e2fs_contigsumsize];
  222         for (i = fs->e2fs_contigsumsize; i > 0; i--)
  223                 if (*lp-- > 0)
  224                         break;
  225         fs->e2fs_maxcluster[cg] = i;
  226 }

Cache object: fbb85de4c48d2f654e0162f8d2e2c353


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