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: releng/9.1/sys/fs/ext2fs/ext2_balloc.c 229549 2012-01-05 01:35:01Z pfg $
   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/inode.h>
   48 #include <fs/ext2fs/ext2fs.h>
   49 #include <fs/ext2fs/fs.h>
   50 #include <fs/ext2fs/ext2_extern.h>
   51 #include <fs/ext2fs/ext2_mount.h>
   52 /*
   53  * Balloc defines the structure of file system storage
   54  * by allocating the physical blocks on a device given
   55  * the inode and the logical block number in a file.
   56  */
   57 int
   58 ext2_balloc(ip, lbn, size, cred, bpp, flags)
   59         struct inode *ip;
   60         int32_t lbn;
   61         int size;
   62         struct ucred *cred;
   63         struct buf **bpp;
   64         int flags;
   65 {
   66         struct m_ext2fs *fs;
   67         struct ext2mount *ump;
   68         int32_t nb;
   69         struct buf *bp, *nbp;
   70         struct vnode *vp = ITOV(ip);
   71         struct indir indirs[NIADDR + 2];
   72         int32_t newb, *bap, pref;
   73         int osize, nsize, num, i, error;
   74 
   75         *bpp = NULL;
   76         if (lbn < 0)
   77                 return (EFBIG);
   78         fs = ip->i_e2fs;
   79         ump = ip->i_ump;
   80 
   81         /*
   82          * check if this is a sequential block allocation. 
   83          * If so, increment next_alloc fields to allow ext2_blkpref 
   84          * to make a good guess
   85          */
   86         if (lbn == ip->i_next_alloc_block + 1) {
   87                 ip->i_next_alloc_block++;
   88                 ip->i_next_alloc_goal++;
   89         }
   90 
   91         /*
   92          * The first NDADDR blocks are direct blocks
   93          */
   94         if (lbn < NDADDR) {
   95                 nb = ip->i_db[lbn];
   96                 /* no new block is to be allocated, and no need to expand
   97                    the file */
   98                 if (nb != 0 && ip->i_size >= (lbn + 1) * fs->e2fs_bsize) {
   99                         error = bread(vp, lbn, fs->e2fs_bsize, NOCRED, &bp);
  100                         if (error) {
  101                                 brelse(bp);
  102                                 return (error);
  103                         }
  104                         bp->b_blkno = fsbtodb(fs, nb);
  105                         *bpp = bp;
  106                         return (0);
  107                 }
  108                 if (nb != 0) {
  109                         /*
  110                          * Consider need to reallocate a fragment.
  111                          */
  112                         osize = fragroundup(fs, blkoff(fs, ip->i_size));
  113                         nsize = fragroundup(fs, size);
  114                         if (nsize <= osize) {
  115                                 error = bread(vp, lbn, osize, NOCRED, &bp);
  116                                 if (error) {
  117                                         brelse(bp);
  118                                         return (error);
  119                                 }
  120                                 bp->b_blkno = fsbtodb(fs, nb);
  121                         } else {
  122                         /* Godmar thinks: this shouldn't happen w/o fragments */
  123                                 printf("nsize %d(%d) > osize %d(%d) nb %d\n", 
  124                                         (int)nsize, (int)size, (int)osize, 
  125                                         (int)ip->i_size, (int)nb);
  126                                 panic(
  127                                     "ext2_balloc: Something is terribly wrong");
  128 /*
  129  * please note there haven't been any changes from here on -
  130  * FFS seems to work.
  131  */
  132                         }
  133                 } else {
  134                         if (ip->i_size < (lbn + 1) * fs->e2fs_bsize)
  135                                 nsize = fragroundup(fs, size);
  136                         else
  137                                 nsize = fs->e2fs_bsize;
  138                         EXT2_LOCK(ump);
  139                         error = ext2_alloc(ip, lbn,
  140                             ext2_blkpref(ip, lbn, (int)lbn, &ip->i_db[0], 0),
  141                             nsize, cred, &newb);
  142                         if (error)
  143                                 return (error);
  144                         bp = getblk(vp, lbn, nsize, 0, 0, 0);
  145                         bp->b_blkno = fsbtodb(fs, newb);
  146                         if (flags & BA_CLRBUF)
  147                                 vfs_bio_clrbuf(bp);
  148                 }
  149                 ip->i_db[lbn] = dbtofsb(fs, bp->b_blkno);
  150                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  151                 *bpp = bp;
  152                 return (0);
  153         }
  154         /*
  155          * Determine the number of levels of indirection.
  156          */
  157         pref = 0;
  158         if ((error = ext2_getlbns(vp, lbn, indirs, &num)) != 0)
  159                 return (error);
  160 #ifdef DIAGNOSTIC
  161         if (num < 1)
  162                 panic ("ext2_balloc: ext2_getlbns returned indirect block");
  163 #endif
  164         /*
  165          * Fetch the first indirect block allocating if necessary.
  166          */
  167         --num;
  168         nb = ip->i_ib[indirs[0].in_off];
  169         if (nb == 0) {
  170                 EXT2_LOCK(ump);
  171                 pref = ext2_blkpref(ip, lbn, indirs[0].in_off + 
  172                                              EXT2_NDIR_BLOCKS, &ip->i_db[0], 0);
  173                 if ((error = ext2_alloc(ip, lbn, pref, 
  174                         (int)fs->e2fs_bsize, cred, &newb)))
  175                         return (error);
  176                 nb = newb;
  177                 bp = getblk(vp, indirs[1].in_lbn, fs->e2fs_bsize, 0, 0, 0);
  178                 bp->b_blkno = fsbtodb(fs, newb);
  179                 vfs_bio_clrbuf(bp);
  180                 /*
  181                  * Write synchronously so that indirect blocks
  182                  * never point at garbage.
  183                  */
  184                 if ((error = bwrite(bp)) != 0) {
  185                         ext2_blkfree(ip, nb, fs->e2fs_bsize);
  186                         return (error);
  187                 }
  188                 ip->i_ib[indirs[0].in_off] = newb;
  189                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  190         }
  191         /*
  192          * Fetch through the indirect blocks, allocating as necessary.
  193          */
  194         for (i = 1;;) {
  195                 error = bread(vp,
  196                     indirs[i].in_lbn, (int)fs->e2fs_bsize, NOCRED, &bp);
  197                 if (error) {
  198                         brelse(bp);
  199                         return (error);
  200                 }
  201                 bap = (int32_t *)bp->b_data;
  202                 nb = bap[indirs[i].in_off];
  203                 if (i == num)
  204                         break;
  205                 i += 1;
  206                 if (nb != 0) {
  207                         bqrelse(bp);
  208                         continue;
  209                 }
  210                 EXT2_LOCK(ump);
  211                 if (pref == 0)
  212                         pref = ext2_blkpref(ip, lbn, indirs[i].in_off, bap,
  213                                                 bp->b_lblkno);
  214                 error =  ext2_alloc(ip, lbn, pref, (int)fs->e2fs_bsize, cred, &newb);
  215                 if (error) {
  216                         brelse(bp);
  217                         return (error);
  218                 }
  219                 nb = newb;
  220                 nbp = getblk(vp, indirs[i].in_lbn, fs->e2fs_bsize, 0, 0, 0);
  221                 nbp->b_blkno = fsbtodb(fs, nb);
  222                 vfs_bio_clrbuf(nbp);
  223                 /*
  224                  * Write synchronously so that indirect blocks
  225                  * never point at garbage.
  226                  */
  227                 if ((error = bwrite(nbp)) != 0) {
  228                         ext2_blkfree(ip, nb, fs->e2fs_bsize);
  229                         EXT2_UNLOCK(ump);
  230                         brelse(bp);
  231                         return (error);
  232                 }
  233                 bap[indirs[i - 1].in_off] = nb;
  234                 /*
  235                  * If required, write synchronously, otherwise use
  236                  * delayed write.
  237                  */
  238                 if (flags & IO_SYNC) {
  239                         bwrite(bp);
  240                 } else {
  241                         if (bp->b_bufsize == fs->e2fs_bsize)
  242                                 bp->b_flags |= B_CLUSTEROK;
  243                         bdwrite(bp);
  244                 }
  245         }
  246         /*
  247          * Get the data block, allocating if necessary.
  248          */
  249         if (nb == 0) {
  250                 EXT2_LOCK(ump);
  251                 pref = ext2_blkpref(ip, lbn, indirs[i].in_off, &bap[0], 
  252                                 bp->b_lblkno);
  253                 if ((error = ext2_alloc(ip,
  254                     lbn, pref, (int)fs->e2fs_bsize, cred, &newb)) != 0) {
  255                         brelse(bp);
  256                         return (error);
  257                 }
  258                 nb = newb;
  259                 nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  260                 nbp->b_blkno = fsbtodb(fs, nb);
  261                 if (flags & BA_CLRBUF)
  262                         vfs_bio_clrbuf(nbp);
  263                 bap[indirs[i].in_off] = nb;
  264                 /*
  265                  * If required, write synchronously, otherwise use
  266                  * delayed write.
  267                  */
  268                 if (flags & IO_SYNC) {
  269                         bwrite(bp);
  270                 } else {
  271                 if (bp->b_bufsize == fs->e2fs_bsize)
  272                                 bp->b_flags |= B_CLUSTEROK;
  273                         bdwrite(bp);
  274                 }
  275                 *bpp = nbp;
  276                 return (0);
  277         }
  278         brelse(bp);
  279         if (flags & BA_CLRBUF) {
  280                 int seqcount = (flags & BA_SEQMASK) >> BA_SEQSHIFT;
  281                 if (seqcount && (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
  282                         error = cluster_read(vp, ip->i_size, lbn,
  283                             (int)fs->e2fs_bsize, NOCRED,
  284                             MAXBSIZE, seqcount, &nbp);
  285                 } else {
  286                         error = bread(vp, lbn, (int)fs->e2fs_bsize, NOCRED, &nbp);
  287                 }
  288                 if (error) {
  289                         brelse(nbp);
  290                         return (error);
  291                 }
  292         } else {
  293                 nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  294                 nbp->b_blkno = fsbtodb(fs, nb);
  295         }
  296         *bpp = nbp;
  297         return (0);
  298 }
  299 

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