mirror of https://github.com/dzavalishin/oskit/
456 lines
18 KiB
C
Executable File
456 lines
18 KiB
C
Executable File
/*
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* Mach Operating System
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* Copyright (c) 1991,1990 Carnegie Mellon University
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie Mellon
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* the rights to redistribute these changes.
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*/
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/*
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* Copyright (c) 1982, 1986 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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* @(#)fs.h 7.7 (Berkeley) 5/9/89
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*/
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/*
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* Each disk drive contains some number of file systems.
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* A file system consists of a number of cylinder groups.
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* Each cylinder group has inodes and data.
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*
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* A file system is described by its super-block, which in turn
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* describes the cylinder groups. The super-block is critical
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* data and is replicated in each cylinder group to protect against
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* catastrophic loss. This is done at `newfs' time and the critical
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* super-block data does not change, so the copies need not be
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* referenced further unless disaster strikes.
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*
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* For file system fs, the offsets of the various blocks of interest
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* are given in the super block as:
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* [fs->fs_sblkno] Super-block
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* [fs->fs_cblkno] Cylinder group block
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* [fs->fs_iblkno] Inode blocks
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* [fs->fs_dblkno] Data blocks
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* The beginning of cylinder group cg in fs, is given by
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* the ``cgbase(fs, cg)'' macro.
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*
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* The first boot and super blocks are given in absolute disk addresses.
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* The byte-offset forms are preferred, as they don't imply a sector size.
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*/
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#define BBSIZE 8192
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#define SBSIZE 8192
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#define BBOFF ((off_t)(0))
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#define SBOFF ((off_t)(BBOFF + BBSIZE))
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#define BBLOCK ((daddr_t)(0))
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#define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
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/*
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* Addresses stored in inodes are capable of addressing fragments
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* of `blocks'. File system blocks of at most size MAXBSIZE can
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* be optionally broken into 2, 4, or 8 pieces, each of which is
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* addressible; these pieces may be DEV_BSIZE, or some multiple of
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* a DEV_BSIZE unit.
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*
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* Large files consist of exclusively large data blocks. To avoid
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* undue wasted disk space, the last data block of a small file may be
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* allocated as only as many fragments of a large block as are
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* necessary. The file system format retains only a single pointer
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* to such a fragment, which is a piece of a single large block that
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* has been divided. The size of such a fragment is determinable from
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* information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
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*
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* The file system records space availability at the fragment level;
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* to determine block availability, aligned fragments are examined.
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*
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* The root inode is the root of the file system.
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* Inode 0 can't be used for normal purposes and
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* historically bad blocks were linked to inode 1,
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* thus the root inode is 2. (inode 1 is no longer used for
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* this purpose, however numerous dump tapes make this
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* assumption, so we are stuck with it)
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*/
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#define ROOTINO ((ino_t)2) /* i number of all roots */
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/*
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* MINBSIZE is the smallest allowable block size.
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* In order to insure that it is possible to create files of size
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* 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
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* MINBSIZE must be big enough to hold a cylinder group block,
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* thus changes to (struct cg) must keep its size within MINBSIZE.
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* Note that super blocks are always of size SBSIZE,
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* and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
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*/
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#define MINBSIZE 4096
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/*
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* The path name on which the file system is mounted is maintained
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* in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
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* the super block for this name.
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* The limit on the amount of summary information per file system
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* is defined by MAXCSBUFS. It is currently parameterized for a
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* maximum of two million cylinders.
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*/
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#define MAXMNTLEN 512
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#define MAXCSBUFS 32
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/*
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* Per cylinder group information; summarized in blocks allocated
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* from first cylinder group data blocks. These blocks have to be
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* read in from fs_csaddr (size fs_cssize) in addition to the
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* super block.
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*
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* N.B. sizeof(struct csum) must be a power of two in order for
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* the ``fs_cs'' macro to work (see below).
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*/
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struct csum {
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int cs_ndir; /* number of directories */
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int cs_nbfree; /* number of free blocks */
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int cs_nifree; /* number of free inodes */
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int cs_nffree; /* number of free frags */
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};
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/*
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* Super block for a file system.
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*/
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#define FS_MAGIC 0x011954
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struct fs
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{
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int xxx1; /* struct fs *fs_link;*/
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int xxx2; /* struct fs *fs_rlink;*/
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daddr_t fs_sblkno; /* addr of super-block in filesys */
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daddr_t fs_cblkno; /* offset of cyl-block in filesys */
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daddr_t fs_iblkno; /* offset of inode-blocks in filesys */
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daddr_t fs_dblkno; /* offset of first data after cg */
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int fs_cgoffset; /* cylinder group offset in cylinder */
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int fs_cgmask; /* used to calc mod fs_ntrak */
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time_t fs_time; /* last time written */
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int fs_size; /* number of blocks in fs */
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int fs_dsize; /* number of data blocks in fs */
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int fs_ncg; /* number of cylinder groups */
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int fs_bsize; /* size of basic blocks in fs */
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int fs_fsize; /* size of frag blocks in fs */
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int fs_frag; /* number of frags in a block in fs */
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/* these are configuration parameters */
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int fs_minfree; /* minimum percentage of free blocks */
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int fs_rotdelay; /* num of ms for optimal next block */
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int fs_rps; /* disk revolutions per second */
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/* these fields can be computed from the others */
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int fs_bmask; /* ``blkoff'' calc of blk offsets */
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int fs_fmask; /* ``fragoff'' calc of frag offsets */
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int fs_bshift; /* ``lblkno'' calc of logical blkno */
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int fs_fshift; /* ``numfrags'' calc number of frags */
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/* these are configuration parameters */
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int fs_maxcontig; /* max number of contiguous blks */
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int fs_maxbpg; /* max number of blks per cyl group */
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/* these fields can be computed from the others */
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int fs_fragshift; /* block to frag shift */
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int fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
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int fs_sbsize; /* actual size of super block */
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int fs_csmask; /* csum block offset */
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int fs_csshift; /* csum block number */
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int fs_nindir; /* value of NINDIR */
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int fs_inopb; /* value of INOPB */
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int fs_nspf; /* value of NSPF */
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/* yet another configuration parameter */
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int fs_optim; /* optimization preference, see below */
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/* these fields are derived from the hardware */
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int fs_npsect; /* # sectors/track including spares */
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int fs_interleave; /* hardware sector interleave */
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int fs_trackskew; /* sector 0 skew, per track */
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int fs_headswitch; /* head switch time, usec */
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int fs_trkseek; /* track-to-track seek, usec */
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/* sizes determined by number of cylinder groups and their sizes */
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daddr_t fs_csaddr; /* blk addr of cyl grp summary area */
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int fs_cssize; /* size of cyl grp summary area */
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int fs_cgsize; /* cylinder group size */
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/* these fields are derived from the hardware */
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int fs_ntrak; /* tracks per cylinder */
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int fs_nsect; /* sectors per track */
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int fs_spc; /* sectors per cylinder */
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/* this comes from the disk driver partitioning */
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int fs_ncyl; /* cylinders in file system */
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/* these fields can be computed from the others */
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int fs_cpg; /* cylinders per group */
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int fs_ipg; /* inodes per group */
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int fs_fpg; /* blocks per group * fs_frag */
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/* this data must be re-computed after crashes */
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struct csum fs_cstotal; /* cylinder summary information */
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/* these fields are cleared at mount time */
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char fs_fmod; /* super block modified flag */
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char fs_clean; /* file system is clean flag */
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char fs_ronly; /* mounted read-only flag */
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char fs_flags; /* currently unused flag */
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char fs_fsmnt[MAXMNTLEN]; /* name mounted on */
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/* these fields retain the current block allocation info */
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int fs_cgrotor; /* last cg searched */
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#if 1
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int was_fs_csp[MAXCSBUFS];
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#else
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struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */
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#endif
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int fs_cpc; /* cyl per cycle in postbl */
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short fs_opostbl[16][8]; /* old rotation block list head */
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long fs_sparecon[50]; /* reserved for future constants */
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long fs_contigsumsize; /* size of cluster summary array */
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long fs_maxsymlinklen; /* max length of an internal symlink */
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long fs_inodefmt; /* format of on-disk inodes */
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quad fs_maxfilesize; /* maximum representable file size */
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quad fs_qbmask; /* ~fs_bmask - for use with quad size */
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quad fs_qfmask; /* ~fs_fmask - for use with quad size */
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long fs_state; /* validate fs_clean field */
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int fs_postblformat; /* format of positional layout tables */
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int fs_nrpos; /* number of rotaional positions */
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int fs_postbloff; /* (short) rotation block list head */
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int fs_rotbloff; /* (u_char) blocks for each rotation */
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int fs_magic; /* magic number */
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u_char fs_space[1]; /* list of blocks for each rotation */
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/* actually longer */
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};
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/*
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* Preference for optimization.
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*/
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#define FS_OPTTIME 0 /* minimize allocation time */
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#define FS_OPTSPACE 1 /* minimize disk fragmentation */
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/*
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* Rotational layout table format types
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*/
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#define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */
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#define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */
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/*
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* Macros for access to superblock array structures
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*/
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#define fs_postbl(fs, cylno) \
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(((fs)->fs_postblformat == FS_42POSTBLFMT) \
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? ((fs)->fs_opostbl[cylno]) \
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: ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
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#define fs_rotbl(fs) \
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(((fs)->fs_postblformat == FS_42POSTBLFMT) \
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? ((fs)->fs_space) \
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: ((u_char *)((char *)(fs) + (fs)->fs_rotbloff)))
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/*
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* Convert cylinder group to base address of its global summary info.
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*
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* N.B. This macro assumes that sizeof(struct csum) is a power of two.
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*/
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#define fs_cs(fs, indx) \
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fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]
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/*
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* Cylinder group block for a file system.
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*/
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#define CG_MAGIC 0x090255
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struct cg {
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int xxx1; /* struct cg *cg_link;*/
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int cg_magic; /* magic number */
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time_t cg_time; /* time last written */
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int cg_cgx; /* we are the cgx'th cylinder group */
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short cg_ncyl; /* number of cyl's this cg */
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short cg_niblk; /* number of inode blocks this cg */
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int cg_ndblk; /* number of data blocks this cg */
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struct csum cg_cs; /* cylinder summary information */
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int cg_rotor; /* position of last used block */
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int cg_frotor; /* position of last used frag */
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int cg_irotor; /* position of last used inode */
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int cg_frsum[MAXFRAG]; /* counts of available frags */
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int cg_btotoff; /* (long) block totals per cylinder */
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int cg_boff; /* (short) free block positions */
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int cg_iusedoff; /* (char) used inode map */
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int cg_freeoff; /* (u_char) free block map */
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int cg_nextfreeoff; /* (u_char) next available space */
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int cg_sparecon[16]; /* reserved for future use */
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u_char cg_space[1]; /* space for cylinder group maps */
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/* actually longer */
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};
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/*
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* Macros for access to cylinder group array structures
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*/
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#define cg_blktot(cgp) \
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(((cgp)->cg_magic != CG_MAGIC) \
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? (((struct ocg *)(cgp))->cg_btot) \
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: ((int *)((char *)(cgp) + (cgp)->cg_btotoff)))
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#define cg_blks(fs, cgp, cylno) \
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(((cgp)->cg_magic != CG_MAGIC) \
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? (((struct ocg *)(cgp))->cg_b[cylno]) \
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: ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
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#define cg_inosused(cgp) \
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(((cgp)->cg_magic != CG_MAGIC) \
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? (((struct ocg *)(cgp))->cg_iused) \
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: ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
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#define cg_blksfree(cgp) \
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(((cgp)->cg_magic != CG_MAGIC) \
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? (((struct ocg *)(cgp))->cg_free) \
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: ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff)))
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#define cg_chkmagic(cgp) \
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((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
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/*
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* The following structure is defined
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* for compatibility with old file systems.
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*/
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struct ocg {
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int xxx1; /* struct ocg *cg_link;*/
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int xxx2; /* struct ocg *cg_rlink;*/
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time_t cg_time; /* time last written */
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int cg_cgx; /* we are the cgx'th cylinder group */
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short cg_ncyl; /* number of cyl's this cg */
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short cg_niblk; /* number of inode blocks this cg */
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int cg_ndblk; /* number of data blocks this cg */
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struct csum cg_cs; /* cylinder summary information */
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int cg_rotor; /* position of last used block */
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int cg_frotor; /* position of last used frag */
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int cg_irotor; /* position of last used inode */
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int cg_frsum[8]; /* counts of available frags */
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int cg_btot[32]; /* block totals per cylinder */
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short cg_b[32][8]; /* positions of free blocks */
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char cg_iused[256]; /* used inode map */
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int cg_magic; /* magic number */
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u_char cg_free[1]; /* free block map */
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/* actually longer */
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};
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/*
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* Turn file system block numbers into disk block addresses.
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* This maps file system blocks to device size blocks.
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*/
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#define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb)
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#define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb)
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/*
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* Cylinder group macros to locate things in cylinder groups.
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* They calc file system addresses of cylinder group data structures.
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*/
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#define cgbase(fs, c) ((daddr_t)((fs)->fs_fpg * (c)))
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#define cgstart(fs, c) \
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(cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
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#define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */
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#define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */
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#define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */
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#define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */
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/*
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* Macros for handling inode numbers:
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* inode number to file system block offset.
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* inode number to cylinder group number.
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* inode number to file system block address.
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*/
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#define itoo(fs, x) ((x) % INOPB(fs))
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#define itog(fs, x) ((x) / (fs)->fs_ipg)
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#define itod(fs, x) \
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((daddr_t)(cgimin(fs, itog(fs, x)) + \
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(blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
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/*
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* Give cylinder group number for a file system block.
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* Give cylinder group block number for a file system block.
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*/
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#define dtog(fs, d) ((d) / (fs)->fs_fpg)
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#define dtogd(fs, d) ((d) % (fs)->fs_fpg)
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/*
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* Extract the bits for a block from a map.
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* Compute the cylinder and rotational position of a cyl block addr.
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*/
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#define blkmap(fs, map, loc) \
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(((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
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#define cbtocylno(fs, bno) \
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((bno) * NSPF(fs) / (fs)->fs_spc)
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#define cbtorpos(fs, bno) \
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(((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
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(bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
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(fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
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/*
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* The following macros optimize certain frequently calculated
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* quantities by using shifts and masks in place of divisions
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* modulos and multiplications.
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*/
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#define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
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((loc) & ~(fs)->fs_bmask)
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#define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \
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((loc) & ~(fs)->fs_fmask)
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#define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
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((loc) >> (fs)->fs_bshift)
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#define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
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((loc) >> (fs)->fs_fshift)
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#define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \
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(((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
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#define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
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(((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
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#define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \
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((frags) >> (fs)->fs_fragshift)
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#define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \
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((blks) << (fs)->fs_fragshift)
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#define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \
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((fsb) & ((fs)->fs_frag - 1))
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#define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \
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((fsb) &~ ((fs)->fs_frag - 1))
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|
|
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/*
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|
* Determine the number of available frags given a
|
|
* percentage to hold in reserve
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|
*/
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|
#define freespace(fs, percentreserved) \
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|
(blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
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|
(fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
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|
|
|
/*
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|
* Determining the size of a file block in the file system.
|
|
*/
|
|
#define blksize(fs, ip, lbn) \
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|
(((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
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|
? (fs)->fs_bsize \
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|
: (fragroundup(fs, blkoff(fs, (ip)->i_size))))
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|
#define dblksize(fs, dip, lbn) \
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|
(((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
|
|
? (fs)->fs_bsize \
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|
: (fragroundup(fs, blkoff(fs, (dip)->di_size))))
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|
|
|
/*
|
|
* Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
|
|
*/
|
|
#define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift)
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|
#define NSPF(fs) ((fs)->fs_nspf)
|
|
|
|
/*
|
|
* INOPB is the number of inodes in a secondary storage block.
|
|
*/
|
|
#define INOPB(fs) ((fs)->fs_inopb)
|
|
#define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift)
|
|
|
|
/*
|
|
* NINDIR is the number of indirects in a file system block.
|
|
*/
|
|
#define NINDIR(fs) ((fs)->fs_nindir)
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|
|