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_balloc.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_balloc.c        8.4 (Berkeley) 9/23/93
   36  * $FreeBSD: stable/11/sys/fs/ext2fs/ext2_balloc.c 350385 2019-07-27 19:29:28Z fsu $
   37  */
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/bio.h>
   42 #include <sys/buf.h>
   43 #include <sys/lock.h>
   44 #include <sys/mount.h>
   45 #include <sys/vnode.h>
   46 
   47 #include <fs/ext2fs/fs.h>
   48 #include <fs/ext2fs/inode.h>
   49 #include <fs/ext2fs/ext2fs.h>
   50 #include <fs/ext2fs/ext2_dinode.h>
   51 #include <fs/ext2fs/ext2_extern.h>
   52 #include <fs/ext2fs/ext2_mount.h>
   53 
   54 /*
   55  * Balloc defines the structure of filesystem storage
   56  * by allocating the physical blocks on a device given
   57  * the inode and the logical block number in a file.
   58  */
   59 int
   60 ext2_balloc(struct inode *ip, e2fs_lbn_t lbn, int size, struct ucred *cred,
   61     struct buf **bpp, int flags)
   62 {
   63         struct m_ext2fs *fs;
   64         struct ext2mount *ump;
   65         struct buf *bp, *nbp;
   66         struct vnode *vp = ITOV(ip);
   67         struct indir indirs[NIADDR + 2];
   68         e4fs_daddr_t nb, newb;
   69         e2fs_daddr_t *bap, pref;
   70         int num, i, error;
   71 
   72         *bpp = NULL;
   73         if (lbn < 0)
   74                 return (EFBIG);
   75         fs = ip->i_e2fs;
   76         ump = ip->i_ump;
   77 
   78         /*
   79          * check if this is a sequential block allocation.
   80          * If so, increment next_alloc fields to allow ext2_blkpref
   81          * to make a good guess
   82          */
   83         if (lbn == ip->i_next_alloc_block + 1) {
   84                 ip->i_next_alloc_block++;
   85                 ip->i_next_alloc_goal++;
   86         }
   87         /*
   88          * The first NDADDR blocks are direct blocks
   89          */
   90         if (lbn < NDADDR) {
   91                 nb = ip->i_db[lbn];
   92                 /*
   93                  * no new block is to be allocated, and no need to expand
   94                  * the file
   95                  */
   96                 if (nb != 0) {
   97                         error = bread(vp, lbn, fs->e2fs_bsize, NOCRED, &bp);
   98                         if (error) {
   99                                 brelse(bp);
  100                                 return (error);
  101                         }
  102                         bp->b_blkno = fsbtodb(fs, nb);
  103                         if (ip->i_size >= (lbn + 1) * fs->e2fs_bsize) {
  104                                 *bpp = bp;
  105                                 return (0);
  106                         }
  107                 } else {
  108                         EXT2_LOCK(ump);
  109                         error = ext2_alloc(ip, lbn,
  110                             ext2_blkpref(ip, lbn, (int)lbn, &ip->i_db[0], 0),
  111                             fs->e2fs_bsize, cred, &newb);
  112                         if (error)
  113                                 return (error);
  114                         bp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  115                         bp->b_blkno = fsbtodb(fs, newb);
  116                         if (flags & BA_CLRBUF)
  117                                 vfs_bio_clrbuf(bp);
  118                 }
  119                 ip->i_db[lbn] = dbtofsb(fs, bp->b_blkno);
  120                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  121                 *bpp = bp;
  122                 return (0);
  123         }
  124         /*
  125          * Determine the number of levels of indirection.
  126          */
  127         pref = 0;
  128         if ((error = ext2_getlbns(vp, lbn, indirs, &num)) != 0)
  129                 return (error);
  130 #ifdef INVARIANTS
  131         if (num < 1)
  132                 panic("ext2_balloc: ext2_getlbns returned indirect block");
  133 #endif
  134         /*
  135          * Fetch the first indirect block allocating if necessary.
  136          */
  137         --num;
  138         nb = ip->i_ib[indirs[0].in_off];
  139         if (nb == 0) {
  140                 EXT2_LOCK(ump);
  141                 pref = ext2_blkpref(ip, lbn, indirs[0].in_off +
  142                     EXT2_NDIR_BLOCKS, &ip->i_db[0], 0);
  143                 if ((error = ext2_alloc(ip, lbn, pref, fs->e2fs_bsize, cred,
  144                     &newb)))
  145                         return (error);
  146                 nb = newb;
  147                 bp = getblk(vp, indirs[1].in_lbn, fs->e2fs_bsize, 0, 0, 0);
  148                 bp->b_blkno = fsbtodb(fs, newb);
  149                 vfs_bio_clrbuf(bp);
  150                 /*
  151                  * Write synchronously so that indirect blocks
  152                  * never point at garbage.
  153                  */
  154                 if ((error = bwrite(bp)) != 0) {
  155                         ext2_blkfree(ip, nb, fs->e2fs_bsize);
  156                         return (error);
  157                 }
  158                 ip->i_ib[indirs[0].in_off] = newb;
  159                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  160         }
  161         /*
  162          * Fetch through the indirect blocks, allocating as necessary.
  163          */
  164         for (i = 1;;) {
  165                 error = bread(vp,
  166                     indirs[i].in_lbn, (int)fs->e2fs_bsize, NOCRED, &bp);
  167                 if (error) {
  168                         brelse(bp);
  169                         return (error);
  170                 }
  171                 bap = (e2fs_daddr_t *)bp->b_data;
  172                 nb = bap[indirs[i].in_off];
  173                 if (i == num)
  174                         break;
  175                 i += 1;
  176                 if (nb != 0) {
  177                         bqrelse(bp);
  178                         continue;
  179                 }
  180                 EXT2_LOCK(ump);
  181                 if (pref == 0)
  182                         pref = ext2_blkpref(ip, lbn, indirs[i].in_off, bap,
  183                             bp->b_lblkno);
  184                 error = ext2_alloc(ip, lbn, pref, (int)fs->e2fs_bsize, cred, &newb);
  185                 if (error) {
  186                         brelse(bp);
  187                         return (error);
  188                 }
  189                 nb = newb;
  190                 nbp = getblk(vp, indirs[i].in_lbn, fs->e2fs_bsize, 0, 0, 0);
  191                 nbp->b_blkno = fsbtodb(fs, nb);
  192                 vfs_bio_clrbuf(nbp);
  193                 /*
  194                  * Write synchronously so that indirect blocks
  195                  * never point at garbage.
  196                  */
  197                 if ((error = bwrite(nbp)) != 0) {
  198                         ext2_blkfree(ip, nb, fs->e2fs_bsize);
  199                         brelse(bp);
  200                         return (error);
  201                 }
  202                 bap[indirs[i - 1].in_off] = nb;
  203                 /*
  204                  * If required, write synchronously, otherwise use
  205                  * delayed write.
  206                  */
  207                 if (flags & IO_SYNC) {
  208                         bwrite(bp);
  209                 } else {
  210                         if (bp->b_bufsize == fs->e2fs_bsize)
  211                                 bp->b_flags |= B_CLUSTEROK;
  212                         bdwrite(bp);
  213                 }
  214         }
  215         /*
  216          * Get the data block, allocating if necessary.
  217          */
  218         if (nb == 0) {
  219                 EXT2_LOCK(ump);
  220                 pref = ext2_blkpref(ip, lbn, indirs[i].in_off, &bap[0],
  221                     bp->b_lblkno);
  222                 if ((error = ext2_alloc(ip,
  223                     lbn, pref, (int)fs->e2fs_bsize, cred, &newb)) != 0) {
  224                         brelse(bp);
  225                         return (error);
  226                 }
  227                 nb = newb;
  228                 nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  229                 nbp->b_blkno = fsbtodb(fs, nb);
  230                 if (flags & BA_CLRBUF)
  231                         vfs_bio_clrbuf(nbp);
  232                 bap[indirs[i].in_off] = nb;
  233                 /*
  234                  * If required, write synchronously, otherwise use
  235                  * delayed write.
  236                  */
  237                 if (flags & IO_SYNC) {
  238                         bwrite(bp);
  239                 } else {
  240                         if (bp->b_bufsize == fs->e2fs_bsize)
  241                                 bp->b_flags |= B_CLUSTEROK;
  242                         bdwrite(bp);
  243                 }
  244                 *bpp = nbp;
  245                 return (0);
  246         }
  247         brelse(bp);
  248         if (flags & BA_CLRBUF) {
  249                 int seqcount = (flags & BA_SEQMASK) >> BA_SEQSHIFT;
  250 
  251                 if (seqcount && (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
  252                         error = cluster_read(vp, ip->i_size, lbn,
  253                             (int)fs->e2fs_bsize, NOCRED,
  254                             MAXBSIZE, seqcount, 0, &nbp);
  255                 } else {
  256                         error = bread(vp, lbn, (int)fs->e2fs_bsize, NOCRED, &nbp);
  257                 }
  258                 if (error) {
  259                         brelse(nbp);
  260                         return (error);
  261                 }
  262         } else {
  263                 nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  264                 nbp->b_blkno = fsbtodb(fs, nb);
  265         }
  266         *bpp = nbp;
  267         return (0);
  268 }

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