FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_subr.c

     /*-
      *  modified for Lites 1.1
      *
      *  Aug 1995, Godmar Back (gback@cs.utah.edu)
      *  University of Utah, Department of Computer Science
      */
     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
     * Copyright (c) 1982, 1986, 1989, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)ffs_subr.c  8.2 (Berkeley) 9/21/93
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    
    #include <sys/proc.h>
    #include <sys/sdt.h>
    #include <sys/systm.h>
    #include <sys/bio.h>
    #include <sys/buf.h>
    #include <sys/lock.h>
    #include <sys/ucred.h>
    #include <sys/vnode.h>
    
    #include <fs/ext2fs/fs.h>
    #include <fs/ext2fs/inode.h>
    #include <fs/ext2fs/ext2fs.h>
    #include <fs/ext2fs/ext2_extern.h>
    #include <fs/ext2fs/fs.h>
    #include <fs/ext2fs/ext2_extents.h>
    #include <fs/ext2fs/ext2_mount.h>
    #include <fs/ext2fs/ext2_dinode.h>
    
    /*
     * Return buffer with the contents of block "offset" from the beginning of
     * directory "ip".  If "res" is non-zero, fill it in with a pointer to the
     * remaining space in the directory.
     */
    int
    ext2_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
    {
            struct inode *ip;
            struct m_ext2fs *fs;
            struct buf *bp;
            e2fs_lbn_t lbn;
            int error, bsize;
    
            ip = VTOI(vp);
            fs = ip->i_e2fs;
            lbn = lblkno(fs, offset);
            bsize = blksize(fs, ip, lbn);
    
            if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
                    brelse(bp);
                    return (error);
            }
            error = ext2_dir_blk_csum_verify(ip, bp);
            if (error != 0) {
                    brelse(bp);
                    return (error);
            }
            if (res)
                    *res = (char *)bp->b_data + blkoff(fs, offset);
    
            *bpp = bp;
    
            return (0);
    }
    
    /*
     * Update the cluster map because of an allocation of free like ffs.
     *
    * Cnt == 1 means free; cnt == -1 means allocating.
    */
   void
   ext2_clusteracct(struct m_ext2fs *fs, char *bbp, int cg, e4fs_daddr_t bno, int cnt)
   {
           int32_t *sump = fs->e2fs_clustersum[cg].cs_sum;
           int32_t *lp;
           e4fs_daddr_t start, end, loc, forw, back;
           int bit, i;
   
           /* Initialize the cluster summary array. */
           if (fs->e2fs_clustersum[cg].cs_init == 0) {
                   int run = 0;
   
                   bit = 1;
                   loc = 0;
   
                   for (i = 0; i < fs->e2fs_fpg; i++) {
                           if ((bbp[loc] & bit) == 0)
                                   run++;
                           else if (run != 0) {
                                   if (run > fs->e2fs_contigsumsize)
                                           run = fs->e2fs_contigsumsize;
                                   sump[run]++;
                                   run = 0;
                           }
                           if ((i & (NBBY - 1)) != (NBBY - 1))
                                   bit <<= 1;
                           else {
                                   loc++;
                                   bit = 1;
                           }
                   }
                   if (run != 0) {
                           if (run > fs->e2fs_contigsumsize)
                                   run = fs->e2fs_contigsumsize;
                           sump[run]++;
                   }
                   fs->e2fs_clustersum[cg].cs_init = 1;
           }
   
           if (fs->e2fs_contigsumsize <= 0)
                   return;
   
           /* Find the size of the cluster going forward. */
           start = bno + 1;
           end = start + fs->e2fs_contigsumsize;
           if (end > fs->e2fs_fpg)
                   end = fs->e2fs_fpg;
           loc = start / NBBY;
           bit = 1 << (start % NBBY);
           for (i = start; i < end; i++) {
                   if ((bbp[loc] & bit) != 0)
                           break;
                   if ((i & (NBBY - 1)) != (NBBY - 1))
                           bit <<= 1;
                   else {
                           loc++;
                           bit = 1;
                   }
           }
           forw = i - start;
   
           /* Find the size of the cluster going backward. */
           start = bno - 1;
           end = start - fs->e2fs_contigsumsize;
           if (end < 0)
                   end = -1;
           loc = start / NBBY;
           bit = 1 << (start % NBBY);
           for (i = start; i > end; i--) {
                   if ((bbp[loc] & bit) != 0)
                           break;
                   if ((i & (NBBY - 1)) != 0)
                           bit >>= 1;
                   else {
                           loc--;
                           bit = 1 << (NBBY - 1);
                   }
           }
           back = start - i;
   
           /*
            * Account for old cluster and the possibly new forward and
            * back clusters.
            */
           i = back + forw + 1;
           if (i > fs->e2fs_contigsumsize)
                   i = fs->e2fs_contigsumsize;
           sump[i] += cnt;
           if (back > 0)
                   sump[back] -= cnt;
           if (forw > 0)
                   sump[forw] -= cnt;
   
           /* Update cluster summary information. */
           lp = &sump[fs->e2fs_contigsumsize];
           for (i = fs->e2fs_contigsumsize; i > 0; i--)
                   if (*lp-- > 0)
                           break;
           fs->e2fs_maxcluster[cg] = i;
   }

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