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: stable/11/sys/fs/ext2fs/ext2_subr.c 331722 2018-03-29 02:50:57Z eadler $
   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 #include <fs/ext2fs/ext2_extents.h>
   54 #include <fs/ext2fs/ext2_mount.h>
   55 #include <fs/ext2fs/ext2_dinode.h>
   56 
   57 /*
   58  * Return buffer with the contents of block "offset" from the beginning of
   59  * directory "ip".  If "res" is non-zero, fill it in with a pointer to the
   60  * remaining space in the directory.
   61  */
   62 int
   63 ext2_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
   64 {
   65         struct inode *ip;
   66         struct m_ext2fs *fs;
   67         struct buf *bp;
   68         e2fs_lbn_t lbn;
   69         int bsize, error;
   70         daddr_t newblk;
   71         struct ext4_extent *ep;
   72         struct ext4_extent_path path;
   73 
   74         ip = VTOI(vp);
   75         fs = ip->i_e2fs;
   76         lbn = lblkno(fs, offset);
   77         bsize = blksize(fs, ip, lbn);
   78         *bpp = NULL;
   79 
   80         /*
   81          * IN_E4EXTENTS requires special treatment as we can otherwise fall
   82          * back to the normal path.
   83          */
   84         if (!(ip->i_flag & IN_E4EXTENTS))
   85                 goto normal;
   86 
   87         memset(&path, 0, sizeof(path));
   88         if (ext4_ext_find_extent(fs, ip, lbn, &path) == NULL)
   89                 goto normal;
   90         ep = path.ep_ext;
   91         if (ep == NULL)
   92                 goto normal;
   93 
   94         newblk = lbn - ep->e_blk +
   95             (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32);
   96 
   97         if (path.ep_bp != NULL) {
   98                 brelse(path.ep_bp);
   99                 path.ep_bp = NULL;
  100         }
  101         error = bread(ip->i_devvp, fsbtodb(fs, newblk), bsize, NOCRED, &bp);
  102         if (error != 0) {
  103                 brelse(bp);
  104                 return (error);
  105         }
  106         if (res)
  107                 *res = (char *)bp->b_data + blkoff(fs, offset);
  108         /*
  109          * If IN_E4EXTENTS is enabled we would get a wrong offset so
  110          * reset b_offset here.
  111          */
  112         bp->b_offset = lbn * bsize;
  113         *bpp = bp;
  114         return (0);
  115 
  116 normal:
  117         if (*bpp == NULL) {
  118                 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
  119                         brelse(bp);
  120                         return (error);
  121                 }
  122                 if (res)
  123                         *res = (char *)bp->b_data + blkoff(fs, offset);
  124                 *bpp = bp;
  125         }
  126         return (0);
  127 }
  128 
  129 /*
  130  * Update the cluster map because of an allocation of free like ffs.
  131  *
  132  * Cnt == 1 means free; cnt == -1 means allocating.
  133  */
  134 void
  135 ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, daddr_t bno, int cnt)
  136 {
  137         int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
  138         int32_t *lp;
  139         int back, bit, end, forw, i, loc, start;
  140 
  141         /* Initialize the cluster summary array. */
  142         if (fs->e2fs_clustersum[cg].cs_init == 0) {
  143                 int run = 0;
  144 
  145                 bit = 1;
  146                 loc = 0;
  147 
  148                 for (i = 0; i < fs->e2fs->e2fs_fpg; i++) {
  149                         if ((bbp[loc] & bit) == 0)
  150                                 run++;
  151                         else if (run != 0) {
  152                                 if (run > fs->e2fs_contigsumsize)
  153                                         run = fs->e2fs_contigsumsize;
  154                                 sump[run]++;
  155                                 run = 0;
  156                         }
  157                         if ((i & (NBBY - 1)) != (NBBY - 1))
  158                                 bit <<= 1;
  159                         else {
  160                                 loc++;
  161                                 bit = 1;
  162                         }
  163                 }
  164                 if (run != 0) {
  165                         if (run > fs->e2fs_contigsumsize)
  166                                 run = fs->e2fs_contigsumsize;
  167                         sump[run]++;
  168                 }
  169                 fs->e2fs_clustersum[cg].cs_init = 1;
  170         }
  171 
  172         if (fs->e2fs_contigsumsize <= 0)
  173                 return;
  174 
  175         /* Find the size of the cluster going forward. */
  176         start = bno + 1;
  177         end = start + fs->e2fs_contigsumsize;
  178         if (end > fs->e2fs->e2fs_fpg)
  179                 end = fs->e2fs->e2fs_fpg;
  180         loc = start / NBBY;
  181         bit = 1 << (start % NBBY);
  182         for (i = start; i < end; i++) {
  183                 if ((bbp[loc] & bit) != 0)
  184                         break;
  185                 if ((i & (NBBY - 1)) != (NBBY - 1))
  186                         bit <<= 1;
  187                 else {
  188                         loc++;
  189                         bit = 1;
  190                 }
  191         }
  192         forw = i - start;
  193 
  194         /* Find the size of the cluster going backward. */
  195         start = bno - 1;
  196         end = start - fs->e2fs_contigsumsize;
  197         if (end < 0)
  198                 end = -1;
  199         loc = start / NBBY;
  200         bit = 1 << (start % NBBY);
  201         for (i = start; i > end; i--) {
  202                 if ((bbp[loc] & bit) != 0)
  203                         break;
  204                 if ((i & (NBBY - 1)) != 0)
  205                         bit >>= 1;
  206                 else {
  207                         loc--;
  208                         bit = 1 << (NBBY - 1);
  209                 }
  210         }
  211         back = start - i;
  212 
  213         /*
  214          * Account for old cluster and the possibly new forward and
  215          * back clusters.
  216          */
  217         i = back + forw + 1;
  218         if (i > fs->e2fs_contigsumsize)
  219                 i = fs->e2fs_contigsumsize;
  220         sump[i] += cnt;
  221         if (back > 0)
  222                 sump[back] -= cnt;
  223         if (forw > 0)
  224                 sump[forw] -= cnt;
  225 
  226         /* Update cluster summary information. */
  227         lp = &sump[fs->e2fs_contigsumsize];
  228         for (i = fs->e2fs_contigsumsize; i > 0; i--)
  229                 if (*lp-- > 0)
  230                         break;
  231         fs->e2fs_maxcluster[cg] = i;
  232 }

Cache object: eb68432cc4e5c61018bbf216890f4eae


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