The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/ufs/ufs/ufs_bmap.c

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    1 /*-
    2  * Copyright (c) 1989, 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)ufs_bmap.c  8.7 (Berkeley) 3/21/95
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD$");
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/bio.h>
   43 #include <sys/buf.h>
   44 #include <sys/proc.h>
   45 #include <sys/vnode.h>
   46 #include <sys/mount.h>
   47 #include <sys/resourcevar.h>
   48 #include <sys/stat.h>
   49 
   50 #include <ufs/ufs/extattr.h>
   51 #include <ufs/ufs/quota.h>
   52 #include <ufs/ufs/inode.h>
   53 #include <ufs/ufs/ufsmount.h>
   54 #include <ufs/ufs/ufs_extern.h>
   55 
   56 /*
   57  * Bmap converts the logical block number of a file to its physical block
   58  * number on the disk. The conversion is done by using the logical block
   59  * number to index into the array of block pointers described by the dinode.
   60  */
   61 int
   62 ufs_bmap(ap)
   63         struct vop_bmap_args /* {
   64                 struct vnode *a_vp;
   65                 daddr_t a_bn;
   66                 struct bufobj **a_bop;
   67                 daddr_t *a_bnp;
   68                 int *a_runp;
   69                 int *a_runb;
   70         } */ *ap;
   71 {
   72         ufs2_daddr_t blkno;
   73         int error;
   74 
   75         /*
   76          * Check for underlying vnode requests and ensure that logical
   77          * to physical mapping is requested.
   78          */
   79         if (ap->a_bop != NULL)
   80                 *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj;
   81         if (ap->a_bnp == NULL)
   82                 return (0);
   83 
   84         error = ufs_bmaparray(ap->a_vp, ap->a_bn, &blkno, NULL,
   85             ap->a_runp, ap->a_runb);
   86         *ap->a_bnp = blkno;
   87         return (error);
   88 }
   89 
   90 /*
   91  * Indirect blocks are now on the vnode for the file.  They are given negative
   92  * logical block numbers.  Indirect blocks are addressed by the negative
   93  * address of the first data block to which they point.  Double indirect blocks
   94  * are addressed by one less than the address of the first indirect block to
   95  * which they point.  Triple indirect blocks are addressed by one less than
   96  * the address of the first double indirect block to which they point.
   97  *
   98  * ufs_bmaparray does the bmap conversion, and if requested returns the
   99  * array of logical blocks which must be traversed to get to a block.
  100  * Each entry contains the offset into that block that gets you to the
  101  * next block and the disk address of the block (if it is assigned).
  102  */
  103 
  104 int
  105 ufs_bmaparray(vp, bn, bnp, nbp, runp, runb)
  106         struct vnode *vp;
  107         ufs2_daddr_t bn;
  108         ufs2_daddr_t *bnp;
  109         struct buf *nbp;
  110         int *runp;
  111         int *runb;
  112 {
  113         struct inode *ip;
  114         struct buf *bp;
  115         struct ufsmount *ump;
  116         struct mount *mp;
  117         struct vnode *devvp;
  118         struct indir a[NIADDR+1], *ap;
  119         ufs2_daddr_t daddr;
  120         ufs_lbn_t metalbn;
  121         int error, num, maxrun = 0;
  122         int *nump;
  123 
  124         ap = NULL;
  125         ip = VTOI(vp);
  126         mp = vp->v_mount;
  127         ump = VFSTOUFS(mp);
  128         devvp = ump->um_devvp;
  129 
  130         if (runp) {
  131                 maxrun = mp->mnt_iosize_max / mp->mnt_stat.f_iosize - 1;
  132                 *runp = 0;
  133         }
  134 
  135         if (runb) {
  136                 *runb = 0;
  137         }
  138 
  139 
  140         ap = a;
  141         nump = &num;
  142         error = ufs_getlbns(vp, bn, ap, nump);
  143         if (error)
  144                 return (error);
  145 
  146         num = *nump;
  147         if (num == 0) {
  148                 if (bn >= 0 && bn < NDADDR) {
  149                         *bnp = blkptrtodb(ump, DIP(ip, i_db[bn]));
  150                 } else if (bn < 0 && bn >= -NXADDR) {
  151                         *bnp = blkptrtodb(ump, ip->i_din2->di_extb[-1 - bn]);
  152                         if (*bnp == 0)
  153                                 *bnp = -1;
  154                         if (nbp == NULL)
  155                                 panic("ufs_bmaparray: mapping ext data");
  156                         nbp->b_xflags |= BX_ALTDATA;
  157                         return (0);
  158                 } else {
  159                         panic("ufs_bmaparray: blkno out of range");
  160                 }
  161                 /*
  162                  * Since this is FFS independent code, we are out of
  163                  * scope for the definitions of BLK_NOCOPY and
  164                  * BLK_SNAP, but we do know that they will fall in
  165                  * the range 1..um_seqinc, so we use that test and
  166                  * return a request for a zeroed out buffer if attempts
  167                  * are made to read a BLK_NOCOPY or BLK_SNAP block.
  168                  */
  169                 if ((ip->i_flags & SF_SNAPSHOT) && DIP(ip, i_db[bn]) > 0 &&
  170                     DIP(ip, i_db[bn]) < ump->um_seqinc) {
  171                         *bnp = -1;
  172                 } else if (*bnp == 0) {
  173                         if (ip->i_flags & SF_SNAPSHOT)
  174                                 *bnp = blkptrtodb(ump, bn * ump->um_seqinc);
  175                         else
  176                                 *bnp = -1;
  177                 } else if (runp) {
  178                         ufs2_daddr_t bnb = bn;
  179                         for (++bn; bn < NDADDR && *runp < maxrun &&
  180                             is_sequential(ump, DIP(ip, i_db[bn - 1]),
  181                             DIP(ip, i_db[bn]));
  182                             ++bn, ++*runp);
  183                         bn = bnb;
  184                         if (runb && (bn > 0)) {
  185                                 for (--bn; (bn >= 0) && (*runb < maxrun) &&
  186                                         is_sequential(ump, DIP(ip, i_db[bn]),
  187                                                 DIP(ip, i_db[bn+1]));
  188                                                 --bn, ++*runb);
  189                         }
  190                 }
  191                 return (0);
  192         }
  193 
  194 
  195         /* Get disk address out of indirect block array */
  196         daddr = DIP(ip, i_ib[ap->in_off]);
  197 
  198         for (bp = NULL, ++ap; --num; ++ap) {
  199                 /*
  200                  * Exit the loop if there is no disk address assigned yet and
  201                  * the indirect block isn't in the cache, or if we were
  202                  * looking for an indirect block and we've found it.
  203                  */
  204 
  205                 metalbn = ap->in_lbn;
  206                 if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn)
  207                         break;
  208                 /*
  209                  * If we get here, we've either got the block in the cache
  210                  * or we have a disk address for it, go fetch it.
  211                  */
  212                 if (bp)
  213                         bqrelse(bp);
  214 
  215                 bp = getblk(vp, metalbn, mp->mnt_stat.f_iosize, 0, 0, 0);
  216                 if ((bp->b_flags & B_CACHE) == 0) {
  217 #ifdef INVARIANTS
  218                         if (!daddr)
  219                                 panic("ufs_bmaparray: indirect block not in cache");
  220 #endif
  221                         bp->b_blkno = blkptrtodb(ump, daddr);
  222                         bp->b_iocmd = BIO_READ;
  223                         bp->b_flags &= ~B_INVAL;
  224                         bp->b_ioflags &= ~BIO_ERROR;
  225                         vfs_busy_pages(bp, 0);
  226                         bp->b_iooffset = dbtob(bp->b_blkno);
  227                         bstrategy(bp);
  228                         curthread->td_ru.ru_inblock++;
  229                         error = bufwait(bp);
  230                         if (error) {
  231                                 brelse(bp);
  232                                 return (error);
  233                         }
  234                 }
  235 
  236                 if (ip->i_ump->um_fstype == UFS1) {
  237                         daddr = ((ufs1_daddr_t *)bp->b_data)[ap->in_off];
  238                         if (num == 1 && daddr && runp) {
  239                                 for (bn = ap->in_off + 1;
  240                                     bn < MNINDIR(ump) && *runp < maxrun &&
  241                                     is_sequential(ump,
  242                                     ((ufs1_daddr_t *)bp->b_data)[bn - 1],
  243                                     ((ufs1_daddr_t *)bp->b_data)[bn]);
  244                                     ++bn, ++*runp);
  245                                 bn = ap->in_off;
  246                                 if (runb && bn) {
  247                                         for (--bn; bn >= 0 && *runb < maxrun &&
  248                                             is_sequential(ump,
  249                                             ((ufs1_daddr_t *)bp->b_data)[bn],
  250                                             ((ufs1_daddr_t *)bp->b_data)[bn+1]);
  251                                             --bn, ++*runb);
  252                                 }
  253                         }
  254                         continue;
  255                 }
  256                 daddr = ((ufs2_daddr_t *)bp->b_data)[ap->in_off];
  257                 if (num == 1 && daddr && runp) {
  258                         for (bn = ap->in_off + 1;
  259                             bn < MNINDIR(ump) && *runp < maxrun &&
  260                             is_sequential(ump,
  261                             ((ufs2_daddr_t *)bp->b_data)[bn - 1],
  262                             ((ufs2_daddr_t *)bp->b_data)[bn]);
  263                             ++bn, ++*runp);
  264                         bn = ap->in_off;
  265                         if (runb && bn) {
  266                                 for (--bn; bn >= 0 && *runb < maxrun &&
  267                                     is_sequential(ump,
  268                                     ((ufs2_daddr_t *)bp->b_data)[bn],
  269                                     ((ufs2_daddr_t *)bp->b_data)[bn + 1]);
  270                                     --bn, ++*runb);
  271                         }
  272                 }
  273         }
  274         if (bp)
  275                 bqrelse(bp);
  276 
  277         /*
  278          * Since this is FFS independent code, we are out of scope for the
  279          * definitions of BLK_NOCOPY and BLK_SNAP, but we do know that they
  280          * will fall in the range 1..um_seqinc, so we use that test and
  281          * return a request for a zeroed out buffer if attempts are made
  282          * to read a BLK_NOCOPY or BLK_SNAP block.
  283          */
  284         if ((ip->i_flags & SF_SNAPSHOT) && daddr > 0 && daddr < ump->um_seqinc){
  285                 *bnp = -1;
  286                 return (0);
  287         }
  288         *bnp = blkptrtodb(ump, daddr);
  289         if (*bnp == 0) {
  290                 if (ip->i_flags & SF_SNAPSHOT)
  291                         *bnp = blkptrtodb(ump, bn * ump->um_seqinc);
  292                 else
  293                         *bnp = -1;
  294         }
  295         return (0);
  296 }
  297 
  298 /*
  299  * Create an array of logical block number/offset pairs which represent the
  300  * path of indirect blocks required to access a data block.  The first "pair"
  301  * contains the logical block number of the appropriate single, double or
  302  * triple indirect block and the offset into the inode indirect block array.
  303  * Note, the logical block number of the inode single/double/triple indirect
  304  * block appears twice in the array, once with the offset into the i_ib and
  305  * once with the offset into the page itself.
  306  */
  307 int
  308 ufs_getlbns(vp, bn, ap, nump)
  309         struct vnode *vp;
  310         ufs2_daddr_t bn;
  311         struct indir *ap;
  312         int *nump;
  313 {
  314         ufs2_daddr_t blockcnt;
  315         ufs_lbn_t metalbn, realbn;
  316         struct ufsmount *ump;
  317         int i, numlevels, off;
  318 
  319         ump = VFSTOUFS(vp->v_mount);
  320         if (nump)
  321                 *nump = 0;
  322         numlevels = 0;
  323         realbn = bn;
  324         if (bn < 0)
  325                 bn = -bn;
  326 
  327         /* The first NDADDR blocks are direct blocks. */
  328         if (bn < NDADDR)
  329                 return (0);
  330 
  331         /*
  332          * Determine the number of levels of indirection.  After this loop
  333          * is done, blockcnt indicates the number of data blocks possible
  334          * at the previous level of indirection, and NIADDR - i is the number
  335          * of levels of indirection needed to locate the requested block.
  336          */
  337         for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) {
  338                 if (i == 0)
  339                         return (EFBIG);
  340                 blockcnt *= MNINDIR(ump);
  341                 if (bn < blockcnt)
  342                         break;
  343         }
  344 
  345         /* Calculate the address of the first meta-block. */
  346         if (realbn >= 0)
  347                 metalbn = -(realbn - bn + NIADDR - i);
  348         else
  349                 metalbn = -(-realbn - bn + NIADDR - i);
  350 
  351         /*
  352          * At each iteration, off is the offset into the bap array which is
  353          * an array of disk addresses at the current level of indirection.
  354          * The logical block number and the offset in that block are stored
  355          * into the argument array.
  356          */
  357         ap->in_lbn = metalbn;
  358         ap->in_off = off = NIADDR - i;
  359         ap++;
  360         for (++numlevels; i <= NIADDR; i++) {
  361                 /* If searching for a meta-data block, quit when found. */
  362                 if (metalbn == realbn)
  363                         break;
  364 
  365                 blockcnt /= MNINDIR(ump);
  366                 off = (bn / blockcnt) % MNINDIR(ump);
  367 
  368                 ++numlevels;
  369                 ap->in_lbn = metalbn;
  370                 ap->in_off = off;
  371                 ++ap;
  372 
  373                 metalbn -= -1 + off * blockcnt;
  374         }
  375         if (nump)
  376                 *nump = numlevels;
  377         return (0);
  378 }

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