text: /*	$NetBSD: ufs_bmap.c,v 1.5 1997/07/17 23:40:07 fvdl Exp $	*/
  
  /*
   * 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.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 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	8.6 (Berkeley) 1/21/94
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/buf.h>
  #include <sys/proc.h>
  #include <sys/vnode.h>
  #include <sys/mount.h>
  #include <sys/resourcevar.h>
  #include <sys/trace.h>
  
  #include <miscfs/specfs/specdev.h>
  
  #include <ufs/ufs/quota.h>
  #include <ufs/ufs/inode.h>
  #include <ufs/ufs/ufsmount.h>
  #include <ufs/ufs/ufs_extern.h>
  
  /*
   * Bmap converts a 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(v)
  	void *v;
  {
  	struct vop_bmap_args /* {
  		struct vnode *a_vp;
  		daddr_t  a_bn;
  		struct vnode **a_vpp;
  		daddr_t *a_bnp;
  		int *a_runp;
  	} */ *ap = v;
  	/*
  	 * Check for underlying vnode requests and ensure that logical
  	 * to physical mapping is requested.
  	 */
  	if (ap->a_vpp != NULL)
  		*ap->a_vpp = VTOI(ap->a_vp)->i_devvp;
  	if (ap->a_bnp == NULL)
  		return (0);
  
  	return (ufs_bmaparray(ap->a_vp, ap->a_bn, ap->a_bnp, NULL, NULL,
  	    ap->a_runp));
  }
  
  /*
   * 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, ap, nump, runp)
  	struct vnode *vp;
  	register daddr_t bn;
  	daddr_t *bnp;
  	struct indir *ap;
  	int *nump;
  	int *runp;
  {
  	register struct inode *ip;
  	struct buf *bp;
  	struct ufsmount *ump;
  	struct mount *mp;
  	struct vnode *devvp;
  	struct indir a[NIADDR], *xap;
  	daddr_t daddr;
  	long metalbn;
  	int error, maxrun = 0, num;
  
  	ip = VTOI(vp);
  	mp = vp->v_mount;
  	ump = VFSTOUFS(mp);
  #ifdef DIAGNOSTIC
  	if ((ap != NULL && nump == NULL) || (ap == NULL && nump != NULL))
  		panic("ufs_bmaparray: invalid arguments");
  #endif
  
  	if (runp) {
  		/*
  		 * XXX
  		 * If MAXBSIZE is the largest transfer the disks can handle,
  		 * we probably want maxrun to be 1 block less so that we
  		 * don't create a block larger than the device can handle.
  		 */
  		*runp = 0;
  		maxrun = MAXBSIZE / mp->mnt_stat.f_iosize - 1;
  	}
  
  	xap = ap == NULL ? a : ap;
  	if (!nump)
  		nump = &num;
  	if ((error = ufs_getlbns(vp, bn, xap, nump)) != 0)
  		return (error);
  
  	num = *nump;
  	if (num == 0) {
  		*bnp = blkptrtodb(ump, ip->i_ffs_db[bn]);
  		if (*bnp == 0)
  			*bnp = -1;
  		else if (runp)
  			for (++bn; bn < NDADDR && *runp < maxrun &&
  			    is_sequential(ump, ip->i_ffs_db[bn - 1], ip->i_ffs_db[bn]);
  			    ++bn, ++*runp);
  		return (0);
  	}
  
  
  	/* Get disk address out of indirect block array */
  	daddr = ip->i_ffs_ib[xap->in_off];
  
  	devvp = VFSTOUFS(vp->v_mount)->um_devvp;
  	for (bp = NULL, ++xap; --num; ++xap) {
  		/* 
  		 * 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 = xap->in_lbn;
  		if ((daddr == 0 && !incore(vp, 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)
  			brelse(bp);
  
  		xap->in_exists = 1;
  		bp = getblk(vp, metalbn, mp->mnt_stat.f_iosize, 0, 0);
  		if (bp->b_flags & (B_DONE | B_DELWRI)) {
  			trace(TR_BREADHIT, pack(vp, size), metalbn);
  		}
  #ifdef DIAGNOSTIC
  		else if (!daddr)
  			panic("ufs_bmaparry: indirect block not in cache");
  #endif
  		else {
  			trace(TR_BREADMISS, pack(vp, size), metalbn);
  			bp->b_blkno = blkptrtodb(ump, daddr);
  			bp->b_flags |= B_READ;
  			VOP_STRATEGY(bp);
  			curproc->p_stats->p_ru.ru_inblock++;	/* XXX */
  			if ((error = biowait(bp)) != 0) {
  				brelse(bp);
  				return (error);
  			}
  		}
  
  		daddr = ((daddr_t *)bp->b_data)[xap->in_off];
  		if (num == 1 && daddr && runp)
  			for (bn = xap->in_off + 1;
  			    bn < MNINDIR(ump) && *runp < maxrun &&
  			    is_sequential(ump, ((daddr_t *)bp->b_data)[bn - 1],
  			    ((daddr_t *)bp->b_data)[bn]);
  			    ++bn, ++*runp);
  	}
  	if (bp)
  		brelse(bp);
  
  	daddr = blkptrtodb(ump, daddr);
  	*bnp = daddr == 0 ? -1 : daddr;
  	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_ffs_ib and
   * once with the offset into the page itself.
   */
  int
  ufs_getlbns(vp, bn, ap, nump)
  	struct vnode *vp;
  	register daddr_t bn;
  	struct indir *ap;
  	int *nump;
  {
  	long metalbn, realbn;
  	struct ufsmount *ump;
  	int64_t blockcnt;
  	int i, numlevels, off;
  
  	ump = VFSTOUFS(vp->v_mount);
  	if (nump)
  		*nump = 0;
  	numlevels = 0;
  	realbn = bn;
  	if ((long)bn < 0)
  		bn = -(long)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 given 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);
  }
  