1 /* $NetBSD: ufs_bmap.c,v 1.14 2004/06/20 22:20:18 jmc Exp $ */
2 /* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */
5 * SPDX-License-Identifier: BSD-3-Clause
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39 * @(#)ufs_bmap.c 8.8 (Berkeley) 8/11/95
42 #include <sys/cdefs.h>
43 __FBSDID("$FreeBSD$");
45 #include <sys/param.h>
54 #include <ufs/ufs/dinode.h>
55 #include <ufs/ffs/fs.h>
57 #include "ffs/ufs_bswap.h"
58 #include "ffs/ufs_inode.h"
59 #include "ffs/ffs_extern.h"
62 * Create an array of logical block number/offset pairs which represent the
63 * path of indirect blocks required to access a data block. The first "pair"
64 * contains the logical block number of the appropriate single, double or
65 * triple indirect block and the offset into the inode indirect block array.
66 * Note, the logical block number of the inode single/double/triple indirect
67 * block appears twice in the array, once with the offset into the i_ffs_ib and
68 * once with the offset into the page itself.
71 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
73 daddr_t metalbn, realbn;
76 int i, numlevels, off;
79 lognindir = ffs(NINDIR(ip->i_fs)) - 1;
87 assert (bn >= UFS_NDADDR);
90 * Determine the number of levels of indirection. After this loop
91 * is done, blockcnt indicates the number of data blocks possible
92 * at the given level of indirection, and UFS_NIADDR - i is the number
93 * of levels of indirection needed to locate the requested block.
97 for (lbc = 0, i = UFS_NIADDR;; i--, bn -= blockcnt) {
102 blockcnt = (int64_t)1 << lbc;
108 /* Calculate the address of the first meta-block. */
110 metalbn = -(realbn - bn + UFS_NIADDR - i);
112 metalbn = -(-realbn - bn + UFS_NIADDR - i);
115 * At each iteration, off is the offset into the bap array which is
116 * an array of disk addresses at the current level of indirection.
117 * The logical block number and the offset in that block are stored
118 * into the argument array.
120 ap->in_lbn = metalbn;
121 ap->in_off = off = UFS_NIADDR - i;
123 for (++numlevels; i <= UFS_NIADDR; i++) {
124 /* If searching for a meta-data block, quit when found. */
125 if (metalbn == realbn)
129 blockcnt = (int64_t)1 << lbc;
130 off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
133 ap->in_lbn = metalbn;
137 metalbn -= -1 + (off << lbc);