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ufs_bmap.c

/*-
 * Copyright (c) 1989, 1991, 1993
 *    The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 * 4. 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.
 *
 *    @(#)ufs_bmap.c    8.7 (Berkeley) 3/21/95
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/ufs/ufs/ufs_bmap.c,v 1.66 2007/06/01 01:12:45 jeff Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>

#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>

/*
 * Bmap converts the logical block number of a file to its physical block
 * number on the disk. The conversion is done by using the logical block
 * number to index into the array of block pointers described by the dinode.
 */
int
ufs_bmap(ap)
      struct vop_bmap_args /* {
            struct vnode *a_vp;
            daddr_t a_bn;
            struct bufobj **a_bop;
            daddr_t *a_bnp;
            int *a_runp;
            int *a_runb;
      } */ *ap;
{
      ufs2_daddr_t blkno;
      int error;

      /*
       * Check for underlying vnode requests and ensure that logical
       * to physical mapping is requested.
       */
      if (ap->a_bop != NULL)
            *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj;
      if (ap->a_bnp == NULL)
            return (0);

      error = ufs_bmaparray(ap->a_vp, ap->a_bn, &blkno, NULL,
          ap->a_runp, ap->a_runb);
      *ap->a_bnp = blkno;
      return (error);
}

/*
 * Indirect blocks are now on the vnode for the file.  They are given negative
 * logical block numbers.  Indirect blocks are addressed by the negative
 * address of the first data block to which they point.  Double indirect blocks
 * are addressed by one less than the address of the first indirect block to
 * which they point.  Triple indirect blocks are addressed by one less than
 * the address of the first double indirect block to which they point.
 *
 * ufs_bmaparray does the bmap conversion, and if requested returns the
 * array of logical blocks which must be traversed to get to a block.
 * Each entry contains the offset into that block that gets you to the
 * next block and the disk address of the block (if it is assigned).
 */

int
ufs_bmaparray(vp, bn, bnp, nbp, runp, runb)
      struct vnode *vp;
      ufs2_daddr_t bn;
      ufs2_daddr_t *bnp;
      struct buf *nbp;
      int *runp;
      int *runb;
{
      struct inode *ip;
      struct buf *bp;
      struct ufsmount *ump;
      struct mount *mp;
      struct vnode *devvp;
      struct indir a[NIADDR+1], *ap;
      ufs2_daddr_t daddr;
      ufs_lbn_t metalbn;
      int error, num, maxrun = 0;
      int *nump;

      ap = NULL;
      ip = VTOI(vp);
      mp = vp->v_mount;
      ump = VFSTOUFS(mp);
      devvp = ump->um_devvp;

      if (runp) {
            maxrun = mp->mnt_iosize_max / mp->mnt_stat.f_iosize - 1;
            *runp = 0;
      }

      if (runb) {
            *runb = 0;
      }


      ap = a;
      nump = &num;
      error = ufs_getlbns(vp, bn, ap, nump);
      if (error)
            return (error);

      num = *nump;
      if (num == 0) {
            if (bn >= 0 && bn < NDADDR) {
                  *bnp = blkptrtodb(ump, DIP(ip, i_db[bn]));
            } else if (bn < 0 && bn >= -NXADDR) {
                  *bnp = blkptrtodb(ump, ip->i_din2->di_extb[-1 - bn]);
                  if (*bnp == 0)
                        *bnp = -1;
                  if (nbp == NULL)
                        panic("ufs_bmaparray: mapping ext data");
                  nbp->b_xflags |= BX_ALTDATA;
                  return (0);
            } else {
                  panic("ufs_bmaparray: blkno out of range");
            }
            /*
             * Since this is FFS independent code, we are out of
             * scope for the definitions of BLK_NOCOPY and
             * BLK_SNAP, but we do know that they will fall in
             * the range 1..um_seqinc, so we use that test and
             * return a request for a zeroed out buffer if attempts
             * are made to read a BLK_NOCOPY or BLK_SNAP block.
             */
            if ((ip->i_flags & SF_SNAPSHOT) && DIP(ip, i_db[bn]) > 0 &&
                DIP(ip, i_db[bn]) < ump->um_seqinc) {
                  *bnp = -1;
            } else if (*bnp == 0) {
                  if (ip->i_flags & SF_SNAPSHOT)
                        *bnp = blkptrtodb(ump, bn * ump->um_seqinc);
                  else
                        *bnp = -1;
            } else if (runp) {
                  ufs2_daddr_t bnb = bn;
                  for (++bn; bn < NDADDR && *runp < maxrun &&
                      is_sequential(ump, DIP(ip, i_db[bn - 1]),
                      DIP(ip, i_db[bn]));
                      ++bn, ++*runp);
                  bn = bnb;
                  if (runb && (bn > 0)) {
                        for (--bn; (bn >= 0) && (*runb < maxrun) &&
                              is_sequential(ump, DIP(ip, i_db[bn]),
                                    DIP(ip, i_db[bn+1]));
                                    --bn, ++*runb);
                  }
            }
            return (0);
      }


      /* Get disk address out of indirect block array */
      daddr = DIP(ip, i_ib[ap->in_off]);

      for (bp = NULL, ++ap; --num; ++ap) {
            /*
             * Exit the loop if there is no disk address assigned yet and
             * the indirect block isn't in the cache, or if we were
             * looking for an indirect block and we've found it.
             */

            metalbn = ap->in_lbn;
            if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn)
                  break;
            /*
             * If we get here, we've either got the block in the cache
             * or we have a disk address for it, go fetch it.
             */
            if (bp)
                  bqrelse(bp);

            ap->in_exists = 1;
            bp = getblk(vp, metalbn, mp->mnt_stat.f_iosize, 0, 0, 0);
            if ((bp->b_flags & B_CACHE) == 0) {
#ifdef DIAGNOSTIC
                  if (!daddr)
                        panic("ufs_bmaparray: indirect block not in cache");
#endif
                  bp->b_blkno = blkptrtodb(ump, daddr);
                  bp->b_iocmd = BIO_READ;
                  bp->b_flags &= ~B_INVAL;
                  bp->b_ioflags &= ~BIO_ERROR;
                  vfs_busy_pages(bp, 0);
                  bp->b_iooffset = dbtob(bp->b_blkno);
                  bstrategy(bp);
                  curthread->td_ru.ru_inblock++;
                  error = bufwait(bp);
                  if (error) {
                        brelse(bp);
                        return (error);
                  }
            }

            if (ip->i_ump->um_fstype == UFS1) {
                  daddr = ((ufs1_daddr_t *)bp->b_data)[ap->in_off];
                  if (num == 1 && daddr && runp) {
                        for (bn = ap->in_off + 1;
                            bn < MNINDIR(ump) && *runp < maxrun &&
                            is_sequential(ump,
                            ((ufs1_daddr_t *)bp->b_data)[bn - 1],
                            ((ufs1_daddr_t *)bp->b_data)[bn]);
                            ++bn, ++*runp);
                        bn = ap->in_off;
                        if (runb && bn) {
                              for (--bn; bn >= 0 && *runb < maxrun &&
                                  is_sequential(ump,
                                  ((ufs1_daddr_t *)bp->b_data)[bn],
                                  ((ufs1_daddr_t *)bp->b_data)[bn+1]);
                                  --bn, ++*runb);
                        }
                  }
                  continue;
            }
            daddr = ((ufs2_daddr_t *)bp->b_data)[ap->in_off];
            if (num == 1 && daddr && runp) {
                  for (bn = ap->in_off + 1;
                      bn < MNINDIR(ump) && *runp < maxrun &&
                      is_sequential(ump,
                      ((ufs2_daddr_t *)bp->b_data)[bn - 1],
                      ((ufs2_daddr_t *)bp->b_data)[bn]);
                      ++bn, ++*runp);
                  bn = ap->in_off;
                  if (runb && bn) {
                        for (--bn; bn >= 0 && *runb < maxrun &&
                            is_sequential(ump,
                            ((ufs2_daddr_t *)bp->b_data)[bn],
                            ((ufs2_daddr_t *)bp->b_data)[bn + 1]);
                            --bn, ++*runb);
                  }
            }
      }
      if (bp)
            bqrelse(bp);

      /*
       * Since this is FFS independent code, we are out of scope for the
       * definitions of BLK_NOCOPY and BLK_SNAP, but we do know that they
       * will fall in the range 1..um_seqinc, so we use that test and
       * return a request for a zeroed out buffer if attempts are made
       * to read a BLK_NOCOPY or BLK_SNAP block.
       */
      if ((ip->i_flags & SF_SNAPSHOT) && daddr > 0 && daddr < ump->um_seqinc){
            *bnp = -1;
            return (0);
      }
      *bnp = blkptrtodb(ump, daddr);
      if (*bnp == 0) {
            if (ip->i_flags & SF_SNAPSHOT)
                  *bnp = blkptrtodb(ump, bn * ump->um_seqinc);
            else
                  *bnp = -1;
      }
      return (0);
}

/*
 * Create an array of logical block number/offset pairs which represent the
 * path of indirect blocks required to access a data block.  The first "pair"
 * contains the logical block number of the appropriate single, double or
 * triple indirect block and the offset into the inode indirect block array.
 * Note, the logical block number of the inode single/double/triple indirect
 * block appears twice in the array, once with the offset into the i_ib and
 * once with the offset into the page itself.
 */
int
ufs_getlbns(vp, bn, ap, nump)
      struct vnode *vp;
      ufs2_daddr_t bn;
      struct indir *ap;
      int *nump;
{
      ufs2_daddr_t blockcnt;
      ufs_lbn_t metalbn, realbn;
      struct ufsmount *ump;
      int i, numlevels, off;

      ump = VFSTOUFS(vp->v_mount);
      if (nump)
            *nump = 0;
      numlevels = 0;
      realbn = bn;
      if (bn < 0)
            bn = -bn;

      /* The first NDADDR blocks are direct blocks. */
      if (bn < NDADDR)
            return (0);

      /*
       * Determine the number of levels of indirection.  After this loop
       * is done, blockcnt indicates the number of data blocks possible
       * at the previous level of indirection, and NIADDR - i is the number
       * of levels of indirection needed to locate the requested block.
       */
      for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) {
            if (i == 0)
                  return (EFBIG);
            blockcnt *= MNINDIR(ump);
            if (bn < blockcnt)
                  break;
      }

      /* Calculate the address of the first meta-block. */
      if (realbn >= 0)
            metalbn = -(realbn - bn + NIADDR - i);
      else
            metalbn = -(-realbn - bn + NIADDR - i);

      /*
       * At each iteration, off is the offset into the bap array which is
       * an array of disk addresses at the current level of indirection.
       * The logical block number and the offset in that block are stored
       * into the argument array.
       */
      ap->in_lbn = metalbn;
      ap->in_off = off = NIADDR - i;
      ap->in_exists = 0;
      ap++;
      for (++numlevels; i <= NIADDR; i++) {
            /* If searching for a meta-data block, quit when found. */
            if (metalbn == realbn)
                  break;

            blockcnt /= MNINDIR(ump);
            off = (bn / blockcnt) % MNINDIR(ump);

            ++numlevels;
            ap->in_lbn = metalbn;
            ap->in_off = off;
            ap->in_exists = 0;
            ++ap;

            metalbn -= -1 + off * blockcnt;
      }
      if (nump)
            *nump = numlevels;
      return (0);
}

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