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 */
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37 * @(#)ufs_bmap.c 8.8 (Berkeley) 8/11/95
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
43 #include <sys/param.h>
52 #include <ufs/ufs/dinode.h>
53 #include <ufs/ffs/fs.h>
55 #include "ffs/ufs_bswap.h"
56 #include "ffs/ufs_inode.h"
57 #include "ffs/ffs_extern.h"
60 * Create an array of logical block number/offset pairs which represent the
61 * path of indirect blocks required to access a data block. The first "pair"
62 * contains the logical block number of the appropriate single, double or
63 * triple indirect block and the offset into the inode indirect block array.
64 * Note, the logical block number of the inode single/double/triple indirect
65 * block appears twice in the array, once with the offset into the i_ffs_ib and
66 * once with the offset into the page itself.
69 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
71 daddr_t metalbn, realbn;
74 int i, numlevels, off;
77 lognindir = ffs(NINDIR(ip->i_fs)) - 1;
85 assert (bn >= NDADDR);
88 * Determine the number of levels of indirection. After this loop
89 * is done, blockcnt indicates the number of data blocks possible
90 * at the given level of indirection, and NIADDR - i is the number
91 * of levels of indirection needed to locate the requested block.
95 for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) {
100 blockcnt = (int64_t)1 << lbc;
106 /* Calculate the address of the first meta-block. */
108 metalbn = -(realbn - bn + NIADDR - i);
110 metalbn = -(-realbn - bn + NIADDR - i);
113 * At each iteration, off is the offset into the bap array which is
114 * an array of disk addresses at the current level of indirection.
115 * The logical block number and the offset in that block are stored
116 * into the argument array.
118 ap->in_lbn = metalbn;
119 ap->in_off = off = NIADDR - i;
121 for (++numlevels; i <= NIADDR; i++) {
122 /* If searching for a meta-data block, quit when found. */
123 if (metalbn == realbn)
127 blockcnt = (int64_t)1 << lbc;
128 off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
131 ap->in_lbn = metalbn;
135 metalbn -= -1 + (off << lbc);