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5 * This code is derived from software contributed to Berkeley
6 * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension
7 * Support code is derived from software contributed to Berkeley
8 * by Atsushi Murai (amurai@spec.co.jp).
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38 * @(#)cd9660_bmap.c 8.3 (Berkeley) 1/23/94
39 * $FreeBSD: src/sys/isofs/cd9660/cd9660_bmap.c,v 1.8 1999/08/28 00:46:06 peter Exp $
40 * $DragonFly: src/sys/vfs/isofs/cd9660/cd9660_bmap.c,v 1.4 2004/04/12 23:18:55 cpressey Exp $
43 #include <sys/param.h>
44 #include <sys/vnode.h>
45 #include <sys/mount.h>
48 #include "cd9660_node.h"
51 * Bmap converts a the logical block number of a file to its physical block
52 * number on the disk. The conversion is done by using the logical block
53 * number to index into the data block (extent) for the file.
55 * cd9660_bmap(struct vnode *a_vp, daddr_t a_bn, struct vnode **a_vpp,
56 * daddr_t *a_bnp, int *a_runp, int *a_runb)
59 cd9660_bmap(struct vop_bmap_args *ap)
61 struct iso_node *ip = VTOI(ap->a_vp);
62 daddr_t lblkno = ap->a_bn;
66 * Check for underlying vnode requests and ensure that logical
67 * to physical mapping is requested.
69 if (ap->a_vpp != NULL)
70 *ap->a_vpp = ip->i_devvp;
71 if (ap->a_bnp == NULL)
75 * Compute the requested block number
77 bshift = ip->i_mnt->im_bshift;
78 *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
81 * Determine maximum number of readahead blocks following the
87 nblk = (ip->i_size >> bshift) - (lblkno + 1);
90 else if (nblk >= (MAXBSIZE >> bshift))
91 *ap->a_runp = (MAXBSIZE >> bshift) - 1;