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/10.4/sys/fs/ext2fs/ext2_balloc.c 311232 2017-01-04 02:43:33Z 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/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 osize, nsize, 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 && ip->i_size >= (lbn + 1) * fs->e2fs_bsize) {
   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                         *bpp = bp;
  104                         return (0);
  105                 }
  106                 if (nb != 0) {
  107                         /*
  108                          * Consider need to reallocate a fragment.
  109                          */
  110                         osize = fragroundup(fs, blkoff(fs, ip->i_size));
  111                         nsize = fragroundup(fs, size);
  112                         if (nsize <= osize) {
  113                                 error = bread(vp, lbn, osize, NOCRED, &bp);
  114                                 if (error) {
  115                                         brelse(bp);
  116                                         return (error);
  117                                 }
  118                                 bp->b_blkno = fsbtodb(fs, nb);
  119                         } else {
  120                                 /*
  121                                  * Godmar thinks: this shouldn't happen w/o
  122                                  * fragments
  123                                  */
  124                                 printf("nsize %d(%d) > osize %d(%d) nb %d\n",
  125                                     (int)nsize, (int)size, (int)osize,
  126                                     (int)ip->i_size, (int)nb);
  127                                 panic(
  128                                     "ext2_balloc: Something is terribly wrong");
  129 /*
  130  * please note there haven't been any changes from here on -
  131  * FFS seems to work.
  132  */
  133                         }
  134                 } else {
  135                         if (ip->i_size < (lbn + 1) * fs->e2fs_bsize)
  136                                 nsize = fragroundup(fs, size);
  137                         else
  138                                 nsize = fs->e2fs_bsize;
  139                         EXT2_LOCK(ump);
  140                         error = ext2_alloc(ip, lbn,
  141                             ext2_blkpref(ip, lbn, (int)lbn, &ip->i_db[0], 0),
  142                             nsize, cred, &newb);
  143                         if (error)
  144                                 return (error);
  145                         bp = getblk(vp, lbn, nsize, 0, 0, 0);
  146                         bp->b_blkno = fsbtodb(fs, newb);
  147                         if (flags & BA_CLRBUF)
  148                                 vfs_bio_clrbuf(bp);
  149                 }
  150                 ip->i_db[lbn] = dbtofsb(fs, bp->b_blkno);
  151                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  152                 *bpp = bp;
  153                 return (0);
  154         }
  155         /*
  156          * Determine the number of levels of indirection.
  157          */
  158         pref = 0;
  159         if ((error = ext2_getlbns(vp, lbn, indirs, &num)) != 0)
  160                 return (error);
  161 #ifdef INVARIANTS
  162         if (num < 1)
  163                 panic("ext2_balloc: ext2_getlbns returned indirect block");
  164 #endif
  165         /*
  166          * Fetch the first indirect block allocating if necessary.
  167          */
  168         --num;
  169         nb = ip->i_ib[indirs[0].in_off];
  170         if (nb == 0) {
  171                 EXT2_LOCK(ump);
  172                 pref = ext2_blkpref(ip, lbn, indirs[0].in_off +
  173                     EXT2_NDIR_BLOCKS, &ip->i_db[0], 0);
  174                 if ((error = ext2_alloc(ip, lbn, pref, fs->e2fs_bsize, cred,
  175                     &newb)))
  176                         return (error);
  177                 nb = newb;
  178                 bp = getblk(vp, indirs[1].in_lbn, fs->e2fs_bsize, 0, 0, 0);
  179                 bp->b_blkno = fsbtodb(fs, newb);
  180                 vfs_bio_clrbuf(bp);
  181                 /*
  182                  * Write synchronously so that indirect blocks
  183                  * never point at garbage.
  184                  */
  185                 if ((error = bwrite(bp)) != 0) {
  186                         ext2_blkfree(ip, nb, fs->e2fs_bsize);
  187                         return (error);
  188                 }
  189                 ip->i_ib[indirs[0].in_off] = newb;
  190                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  191         }
  192         /*
  193          * Fetch through the indirect blocks, allocating as necessary.
  194          */
  195         for (i = 1;;) {
  196                 error = bread(vp,
  197                     indirs[i].in_lbn, (int)fs->e2fs_bsize, NOCRED, &bp);
  198                 if (error) {
  199                         brelse(bp);
  200                         return (error);
  201                 }
  202                 bap = (e2fs_daddr_t *)bp->b_data;
  203                 nb = bap[indirs[i].in_off];
  204                 if (i == num)
  205                         break;
  206                 i += 1;
  207                 if (nb != 0) {
  208                         bqrelse(bp);
  209                         continue;
  210                 }
  211                 EXT2_LOCK(ump);
  212                 if (pref == 0)
  213                         pref = ext2_blkpref(ip, lbn, indirs[i].in_off, bap,
  214                             bp->b_lblkno);
  215                 error = ext2_alloc(ip, lbn, pref, (int)fs->e2fs_bsize, cred, &newb);
  216                 if (error) {
  217                         brelse(bp);
  218                         return (error);
  219                 }
  220                 nb = newb;
  221                 nbp = getblk(vp, indirs[i].in_lbn, fs->e2fs_bsize, 0, 0, 0);
  222                 nbp->b_blkno = fsbtodb(fs, nb);
  223                 vfs_bio_clrbuf(nbp);
  224                 /*
  225                  * Write synchronously so that indirect blocks
  226                  * never point at garbage.
  227                  */
  228                 if ((error = bwrite(nbp)) != 0) {
  229                         ext2_blkfree(ip, nb, fs->e2fs_bsize);
  230                         EXT2_UNLOCK(ump);
  231                         brelse(bp);
  232                         return (error);
  233                 }
  234                 bap[indirs[i - 1].in_off] = nb;
  235                 /*
  236                  * If required, write synchronously, otherwise use
  237                  * delayed write.
  238                  */
  239                 if (flags & IO_SYNC) {
  240                         bwrite(bp);
  241                 } else {
  242                         if (bp->b_bufsize == fs->e2fs_bsize)
  243                                 bp->b_flags |= B_CLUSTEROK;
  244                         bdwrite(bp);
  245                 }
  246         }
  247         /*
  248          * Get the data block, allocating if necessary.
  249          */
  250         if (nb == 0) {
  251                 EXT2_LOCK(ump);
  252                 pref = ext2_blkpref(ip, lbn, indirs[i].in_off, &bap[0],
  253                     bp->b_lblkno);
  254                 if ((error = ext2_alloc(ip,
  255                     lbn, pref, (int)fs->e2fs_bsize, cred, &newb)) != 0) {
  256                         brelse(bp);
  257                         return (error);
  258                 }
  259                 nb = newb;
  260                 nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  261                 nbp->b_blkno = fsbtodb(fs, nb);
  262                 if (flags & BA_CLRBUF)
  263                         vfs_bio_clrbuf(nbp);
  264                 bap[indirs[i].in_off] = nb;
  265                 /*
  266                  * If required, write synchronously, otherwise use
  267                  * delayed write.
  268                  */
  269                 if (flags & IO_SYNC) {
  270                         bwrite(bp);
  271                 } else {
  272                         if (bp->b_bufsize == fs->e2fs_bsize)
  273                                 bp->b_flags |= B_CLUSTEROK;
  274                         bdwrite(bp);
  275                 }
  276                 *bpp = nbp;
  277                 return (0);
  278         }
  279         brelse(bp);
  280         if (flags & BA_CLRBUF) {
  281                 int seqcount = (flags & BA_SEQMASK) >> BA_SEQSHIFT;
  282 
  283                 if (seqcount && (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
  284                         error = cluster_read(vp, ip->i_size, lbn,
  285                             (int)fs->e2fs_bsize, NOCRED,
  286                             MAXBSIZE, seqcount, 0, &nbp);
  287                 } else {
  288                         error = bread(vp, lbn, (int)fs->e2fs_bsize, NOCRED, &nbp);
  289                 }
  290                 if (error) {
  291                         brelse(nbp);
  292                         return (error);
  293                 }
  294         } else {
  295                 nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
  296                 nbp->b_blkno = fsbtodb(fs, nb);
  297         }
  298         *bpp = nbp;
  299         return (0);
  300 }

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