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/9.2/sys/fs/ext2fs/ext2_subr.c 252234 2013-06-26 04:34:16Z 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(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 bsize, error;
   73 
   74         ip = VTOI(vp);
   75         fs = ip->i_e2fs;
   76         lbn = lblkno(fs, offset);
   77         bsize = blksize(fs, ip, lbn);
   78 
   79         *bpp = NULL;
   80         if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
   81                 brelse(bp);
   82                 return (error);
   83         }
   84         if (res)
   85                 *res = (char *)bp->b_data + blkoff(fs, offset);
   86         *bpp = bp;
   87         return (0);
   88 }
   89 
   90 #ifdef KDB
   91 void
   92 ext2_checkoverlap(struct buf *bp, struct inode *ip)
   93 {
   94         struct buf *ebp, *ep;
   95         int32_t start, last;
   96         struct vnode *vp;
   97 
   98         ebp = &buf[nbuf];
   99         start = bp->b_blkno;
  100         last = start + btodb(bp->b_bcount) - 1;
  101         for (ep = buf; ep < ebp; ep++) {
  102                 if (ep == bp || (ep->b_flags & B_INVAL))
  103                         continue;
  104                 vp = ip->i_ump->um_devvp;
  105                 /* look for overlap */
  106                 if (ep->b_bcount == 0 || ep->b_blkno > last ||
  107                     ep->b_blkno + btodb(ep->b_bcount) <= start)
  108                         continue;
  109                 vprint("Disk overlap", vp);
  110                 (void)printf("\tstart %d, end %d overlap start %lld, end %ld\n",
  111                         start, last, (long long)ep->b_blkno,
  112                         (long)(ep->b_blkno + btodb(ep->b_bcount) - 1));
  113                 panic("Disk buffer overlap");
  114         }
  115 }
  116 #endif /* KDB */
  117 
  118 /*
  119  * Update the cluster map because of an allocation of free like ffs.
  120  *
  121  * Cnt == 1 means free; cnt == -1 means allocating.
  122  */
  123 void
  124 ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, daddr_t bno, int cnt)
  125 {
  126         int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
  127         int32_t *lp;
  128         int back, bit, end, forw, i, loc, start;
  129 
  130         /* Initialize the cluster summary array. */
  131         if (fs->e2fs_clustersum[cg].cs_init == 0) {
  132                 int run = 0;
  133                 bit = 1;
  134                 loc = 0;
  135 
  136                 for (i = 0; i < fs->e2fs->e2fs_fpg; i++) {
  137                         if ((bbp[loc] & bit) == 0)
  138                                 run++;
  139                         else if (run != 0) {
  140                                 if (run > fs->e2fs_contigsumsize)
  141                                         run = fs->e2fs_contigsumsize;
  142                                 sump[run]++;
  143                                 run = 0;
  144                         }
  145                         if ((i & (NBBY - 1)) != (NBBY - 1))
  146                                 bit <<= 1;
  147                         else {
  148                                 loc++;
  149                                 bit = 1;
  150                         }
  151                 }
  152                 if (run != 0) {
  153                         if (run > fs->e2fs_contigsumsize)
  154                                 run = fs->e2fs_contigsumsize;
  155                         sump[run]++;
  156                 }
  157                 fs->e2fs_clustersum[cg].cs_init = 1;
  158         }
  159 
  160         if (fs->e2fs_contigsumsize <= 0)
  161                 return;
  162 
  163         /* Find the size of the cluster going forward. */
  164         start = bno + 1;
  165         end = start + fs->e2fs_contigsumsize;
  166         if (end > fs->e2fs->e2fs_fpg)
  167                 end = fs->e2fs->e2fs_fpg;
  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)) != (NBBY - 1))
  174                         bit <<= 1;
  175                 else {
  176                         loc++;
  177                         bit = 1;
  178                 }
  179         }
  180         forw = i - start;
  181 
  182         /* Find the size of the cluster going backward. */
  183         start = bno - 1;
  184         end = start - fs->e2fs_contigsumsize;
  185         if (end < 0)
  186                 end = -1;
  187         loc = start / NBBY;
  188         bit = 1 << (start % NBBY);
  189         for (i = start; i > end; i--) {
  190                 if ((bbp[loc] & bit) != 0)
  191                         break;
  192                 if ((i & (NBBY - 1)) != 0)
  193                         bit >>= 1;
  194                 else {
  195                         loc--;
  196                         bit = 1 << (NBBY - 1);
  197                 }
  198         }
  199         back = start - i;
  200 
  201         /*
  202          * Account for old cluster and the possibly new forward and
  203          * back clusters.
  204          */
  205         i = back + forw + 1;
  206         if (i > fs->e2fs_contigsumsize)
  207                 i = fs->e2fs_contigsumsize;
  208         sump[i] += cnt;
  209         if (back > 0)
  210                 sump[back] -= cnt;
  211         if (forw > 0)
  212                 sump[forw] -= cnt;
  213 
  214         /* Update cluster summary information. */
  215         lp = &sump[fs->e2fs_contigsumsize];
  216         for (i = fs->e2fs_contigsumsize; i > 0; i--)
  217                 if (*lp-- > 0)
  218                         break;
  219         fs->e2fs_maxcluster[cg] = i;
  220 }

Cache object: f0f619c8f320c5c0501d4444798cbf03


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