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/10.4/sys/fs/ext2fs/ext2_subr.c 311232 2017-01-04 02:43:33Z 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 #include <fs/ext2fs/ext2_extents.h>
   54 #include <fs/ext2fs/ext2_mount.h>
   55 #include <fs/ext2fs/ext2_dinode.h>
   56 
   57 #ifdef KDB
   58 void    ext2_checkoverlap(struct buf *, struct inode *);
   59 #endif
   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 bsize, error;
   74         daddr_t newblk;
   75         struct ext4_extent *ep;
   76         struct ext4_extent_path path;
   77 
   78         ip = VTOI(vp);
   79         fs = ip->i_e2fs;
   80         lbn = lblkno(fs, offset);
   81         bsize = blksize(fs, ip, lbn);
   82         *bpp = NULL;
   83 
   84         /*
   85          * IN_E4EXTENTS requires special treatment as we can otherwise fall
   86          * back to the normal path.
   87          */
   88         if (!(ip->i_flag & IN_E4EXTENTS))
   89                 goto normal;
   90 
   91         memset(&path, 0, sizeof(path));
   92         if (ext4_ext_find_extent(fs, ip, lbn, &path) == NULL)
   93                 goto normal;
   94         ep = path.ep_ext;
   95         if (ep == NULL)
   96                 goto normal;
   97 
   98         newblk = lbn - ep->e_blk +
   99             (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32);
  100 
  101         if (path.ep_bp != NULL) {
  102                 brelse(path.ep_bp);
  103                 path.ep_bp = NULL;
  104         }
  105         error = bread(ip->i_devvp, fsbtodb(fs, newblk), bsize, NOCRED, &bp);
  106         if (error != 0) {
  107                 brelse(bp);
  108                 return (error);
  109         }
  110         if (res)
  111                 *res = (char *)bp->b_data + blkoff(fs, offset);
  112         /*
  113          * If IN_E4EXTENTS is enabled we would get a wrong offset so
  114          * reset b_offset here.
  115          */
  116         bp->b_offset = lbn * bsize;
  117         *bpp = bp;
  118         return (0);
  119 
  120 normal:
  121         if (*bpp == NULL) {
  122                 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
  123                         brelse(bp);
  124                         return (error);
  125                 }
  126                 if (res)
  127                         *res = (char *)bp->b_data + blkoff(fs, offset);
  128                 *bpp = bp;
  129         }
  130         return (0);
  131 }
  132 
  133 #ifdef KDB
  134 void
  135 ext2_checkoverlap(struct buf *bp, struct inode *ip)
  136 {
  137         struct buf *ebp, *ep;
  138         e4fs_daddr_t start, last;
  139         struct vnode *vp;
  140 
  141         ebp = &buf[nbuf];
  142         start = bp->b_blkno;
  143         last = start + btodb(bp->b_bcount) - 1;
  144         for (ep = buf; ep < ebp; ep++) {
  145                 if (ep == bp || (ep->b_flags & B_INVAL))
  146                         continue;
  147                 vp = ip->i_ump->um_devvp;
  148                 /* look for overlap */
  149                 if (ep->b_bcount == 0 || ep->b_blkno > last ||
  150                     ep->b_blkno + btodb(ep->b_bcount) <= start)
  151                         continue;
  152                 vprint("Disk overlap", vp);
  153                 printf("\tstart %jd, end %jd overlap start %jd, end %jd\n",
  154                     (intmax_t)start, (intmax_t)last, (intmax_t)ep->b_blkno,
  155                     (intmax_t)(ep->b_blkno + btodb(ep->b_bcount) - 1));
  156                 panic("ext2_checkoverlap: Disk buffer overlap");
  157         }
  158 }
  159 #endif /* KDB */
  160 
  161 /*
  162  * Update the cluster map because of an allocation of free like ffs.
  163  *
  164  * Cnt == 1 means free; cnt == -1 means allocating.
  165  */
  166 void
  167 ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, daddr_t bno, int cnt)
  168 {
  169         int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
  170         int32_t *lp;
  171         int back, bit, end, forw, i, loc, start;
  172 
  173         /* Initialize the cluster summary array. */
  174         if (fs->e2fs_clustersum[cg].cs_init == 0) {
  175                 int run = 0;
  176 
  177                 bit = 1;
  178                 loc = 0;
  179 
  180                 for (i = 0; i < fs->e2fs->e2fs_fpg; i++) {
  181                         if ((bbp[loc] & bit) == 0)
  182                                 run++;
  183                         else if (run != 0) {
  184                                 if (run > fs->e2fs_contigsumsize)
  185                                         run = fs->e2fs_contigsumsize;
  186                                 sump[run]++;
  187                                 run = 0;
  188                         }
  189                         if ((i & (NBBY - 1)) != (NBBY - 1))
  190                                 bit <<= 1;
  191                         else {
  192                                 loc++;
  193                                 bit = 1;
  194                         }
  195                 }
  196                 if (run != 0) {
  197                         if (run > fs->e2fs_contigsumsize)
  198                                 run = fs->e2fs_contigsumsize;
  199                         sump[run]++;
  200                 }
  201                 fs->e2fs_clustersum[cg].cs_init = 1;
  202         }
  203 
  204         if (fs->e2fs_contigsumsize <= 0)
  205                 return;
  206 
  207         /* Find the size of the cluster going forward. */
  208         start = bno + 1;
  209         end = start + fs->e2fs_contigsumsize;
  210         if (end > fs->e2fs->e2fs_fpg)
  211                 end = fs->e2fs->e2fs_fpg;
  212         loc = start / NBBY;
  213         bit = 1 << (start % NBBY);
  214         for (i = start; i < end; i++) {
  215                 if ((bbp[loc] & bit) != 0)
  216                         break;
  217                 if ((i & (NBBY - 1)) != (NBBY - 1))
  218                         bit <<= 1;
  219                 else {
  220                         loc++;
  221                         bit = 1;
  222                 }
  223         }
  224         forw = i - start;
  225 
  226         /* Find the size of the cluster going backward. */
  227         start = bno - 1;
  228         end = start - fs->e2fs_contigsumsize;
  229         if (end < 0)
  230                 end = -1;
  231         loc = start / NBBY;
  232         bit = 1 << (start % NBBY);
  233         for (i = start; i > end; i--) {
  234                 if ((bbp[loc] & bit) != 0)
  235                         break;
  236                 if ((i & (NBBY - 1)) != 0)
  237                         bit >>= 1;
  238                 else {
  239                         loc--;
  240                         bit = 1 << (NBBY - 1);
  241                 }
  242         }
  243         back = start - i;
  244 
  245         /*
  246          * Account for old cluster and the possibly new forward and
  247          * back clusters.
  248          */
  249         i = back + forw + 1;
  250         if (i > fs->e2fs_contigsumsize)
  251                 i = fs->e2fs_contigsumsize;
  252         sump[i] += cnt;
  253         if (back > 0)
  254                 sump[back] -= cnt;
  255         if (forw > 0)
  256                 sump[forw] -= cnt;
  257 
  258         /* Update cluster summary information. */
  259         lp = &sump[fs->e2fs_contigsumsize];
  260         for (i = fs->e2fs_contigsumsize; i > 0; i--)
  261                 if (*lp-- > 0)
  262                         break;
  263         fs->e2fs_maxcluster[cg] = i;
  264 }

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