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[unix-history] / usr / src / sys / ufs / ffs / ufs_bmap.c
/*
* Copyright (c) 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* %sccs.include.redist.c%
*
* @(#)ufs_bmap.c 8.1 (Berkeley) %G%
*/
#include <sys/param.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(ap)
struct vop_bmap_args /* {
struct vnode *a_vp;
daddr_t a_bn;
struct vnode **a_vpp;
daddr_t *a_bnp;
int *a_runp;
} */ *ap;
{
/*
* 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 *bap, daddr;
long metalbn;
int bb, error, maxrun, num, off;
struct vop_strategy_args vop_strategy_a;
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))
return (error);
num = *nump;
if (num == 0) {
*bnp = blkptrtodb(ump, ip->i_db[bn]);
if (*bnp == 0)
*bnp = -1;
else if (runp)
for (++bn; bn < NDADDR && *runp < maxrun &&
is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]);
++bn, ++*runp);
return (0);
}
/* Get disk address out of indirect block array */
daddr = ip->i_ib[xap->in_off];
/* Fetch through the indirect blocks. */
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)) {
brelse(bp);
return (error);
}
}
daddr = bp->b_un.b_daddr[xap->in_off];
if (num == 1 && daddr && runp)
for (bn = xap->in_off + 1;
bn < MNINDIR(ump) && *runp < maxrun &&
is_sequential(ump, bp->b_un.b_daddr[bn - 1],
bp->b_un.b_daddr[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_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;
int j, numlevels, off, sh;
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, sh indicates the number of data blocks possible at the
* given level of indirection, and NIADDR - j is the number of levels
* of indirection needed to locate the requested block.
*/
bn -= NDADDR;
sh = 1;
for (j = NIADDR; j > 0; j--) {
sh *= MNINDIR(ump);
if (bn < sh)
break;
bn -= sh;
}
if (j == 0)
return (EFBIG);
/* Calculate the address of the first meta-block. */
if (realbn >= 0)
metalbn = -(realbn - bn + NIADDR - j);
else
metalbn = -(-realbn - bn + NIADDR - j);
/*
* 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.
*/
++numlevels;
ap->in_lbn = metalbn;
ap->in_off = off = NIADDR - j;
ap->in_exists = 0;
ap++;
for (; j <= NIADDR; j++) {
/* If searching for a meta-data block, quit when found. */
if (metalbn == realbn)
break;
sh /= MNINDIR(ump);
off = (bn / sh) % MNINDIR(ump);
++numlevels;
ap->in_lbn = metalbn;
ap->in_off = off;
ap->in_exists = 0;
++ap;
metalbn -= -1 + off * sh;
}
if (nump)
*nump = numlevels;
return (0);
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.