fs.h

Go to the documentation of this file.

/*  $NetBSD: fs.h,v 1.43 2004/03/21 18:48:24 dsl Exp $  */

/*
 * Copyright (c) 1982, 1986, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *  @(#)fs.h    8.13 (Berkeley) 3/21/95
 */

#ifndef _UFS_FFS_FS_H_
#define _UFS_FFS_FS_H_

#include "type.h"

/*
 * Each disk drive contains some number of file systems.
 * A file system consists of a number of cylinder groups.
 * Each cylinder group has inodes and data.
 *
 * A file system is described by its super-block, which in turn
 * describes the cylinder groups.  The super-block is critical
 * data and is replicated in each cylinder group to protect against
 * catastrophic loss.  This is done at `newfs' time and the critical
 * super-block data does not change, so the copies need not be
 * referenced further unless disaster strikes.
 *
 * For file system fs, the offsets of the various blocks of interest
 * are given in the super block as:
 *  [fs->fs_sblkno]     Super-block
 *  [fs->fs_cblkno]     Cylinder group block
 *  [fs->fs_iblkno]     Inode blocks
 *  [fs->fs_dblkno]     Data blocks
 * The beginning of cylinder group cg in fs, is given by
 * the ``cgbase(fs, cg)'' macro.
 *
 * Depending on the architecture and the media, the superblock may
 * reside in any one of four places. For tiny media where every block 
 * counts, it is placed at the very front of the partition. Historically,
 * UFS1 placed it 8K from the front to leave room for the disk label and
 * a small bootstrap. For UFS2 it got moved to 64K from the front to leave
 * room for the disk label and a bigger bootstrap, and for really piggy
 * systems we check at 256K from the front if the first three fail. In
 * all cases the size of the superblock will be SBLOCKSIZE. All values are
 * given in byte-offset form, so they do not imply a sector size. The
 * SBLOCKSEARCH specifies the order in which the locations should be searched.
 *
 * Unfortunately the UFS2/FFSv2 change was done without adequate consideration
 * of backward compatibility.  In particular 'newfs' for a FFSv2 partition
 * must overwrite any old FFSv1 superblock at 8k, and preferrably as many
 * of the alternates as it can find - otherwise attempting to mount on a
 * system that only supports FFSv1 is likely to succeed!.
 * For a small FFSv1 filesystem, an old FFSv2 superblock can be left on
 * the disk, and a system that tries to find an FFSv2 filesystem in preference
 * to and FFSv1 one (as NetBSD does) can mount the old FFSv2 filesystem.
 * As a added bonus, the 'first alternate' superblock of a FFSv1 filesystem
 * with 64k blocks is at 64k - just where the code looks first when playing
 * 'hunt the superblock'.
 *
 * The ffsv2 superblock layout (which might contain an ffsv1 filesystem)
 * can be detected by checking for sb->fs_old_flags & FS_FLAGS_UPDATED.
 * This is the default suberblock type for NetBSD since ffsv2 support was added.
 */
#define BBSIZE      8192
#define BBOFF       ((off_t)(0))
#define BBLOCK      ((daddr_t)(0))

#define SBLOCK_FLOPPY      0
#define SBLOCK_UFS1     8192
#define SBLOCK_UFS2    65536
#define SBLOCK_PIGGY  262144
#define SBLOCKSIZE      8192
/*
 * NB: Do not, under any circumstances, look for an ffsv1 filesystem at
 * SBLOCK_UFS2.  Doing so will find the wrong superblock for filesystems
 * with a 64k block size.
 */
#define SBLOCKSEARCH \
    { SBLOCK_UFS2, SBLOCK_UFS1, SBLOCK_FLOPPY, SBLOCK_PIGGY, -1 }

/*
 * Max number of fragments per block. This value is NOT tweakable.
 */
#define MAXFRAG     8



/*
 * Addresses stored in inodes are capable of addressing fragments
 * of `blocks'. File system blocks of at most size MAXBSIZE can
 * be optionally broken into 2, 4, or 8 pieces, each of which is
 * addressable; these pieces may be DEV_BSIZE, or some multiple of
 * a DEV_BSIZE unit.
 *
 * Large files consist of exclusively large data blocks.  To avoid
 * undue wasted disk space, the last data block of a small file may be
 * allocated as only as many fragments of a large block as are
 * necessary.  The file system format retains only a single pointer
 * to such a fragment, which is a piece of a single large block that
 * has been divided.  The size of such a fragment is determinable from
 * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
 *
 * The file system records space availability at the fragment level;
 * to determine block availability, aligned fragments are examined.
 */

/*
 * MINBSIZE is the smallest allowable block size.
 * In order to insure that it is possible to create files of size
 * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
 * MINBSIZE must be big enough to hold a cylinder group block,
 * thus changes to (struct cg) must keep its size within MINBSIZE.
 * Note that super blocks are always of size SBSIZE,
 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
 */
#define MINBSIZE    4096

/*
 * The path name on which the file system is mounted is maintained
 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
 * the super block for this name.
 */
#define MAXMNTLEN   468

/*
 * The volume name for this filesystem is maintained in fs_volname.
 * MAXVOLLEN defines the length of the buffer allocated.
 * This space used to be part of of fs_fsmnt.
 */
#define MAXVOLLEN   32

/*
 * There is a 128-byte region in the superblock reserved for in-core
 * pointers to summary information. Originally this included an array
 * of pointers to blocks of struct csum; now there are just four
 * pointers and the remaining space is padded with fs_ocsp[].
 * NOCSPTRS determines the size of this padding. One pointer (fs_csp)
 * is taken away to point to a contiguous array of struct csum for
 * all cylinder groups; a second (fs_maxcluster) points to an array
 * of cluster sizes that is computed as cylinder groups are inspected;
 * the third (fs_contigdirs) points to an array that tracks the
 * creation of new directories; and the fourth (fs_active) is used
 * by snapshots.
 */
#define NOCSPTRS    ((128 / sizeof(void *)) - 4)

/*
 * A summary of contiguous blocks of various sizes is maintained
 * in each cylinder group. Normally this is set by the initial
 * value of fs_maxcontig. To conserve space, a maximum summary size
 * is set by FS_MAXCONTIG.
 */
#define FS_MAXCONTIG    16

/*
 * Unused value currently, FreeBSD compat.
 */
#define FSMAXSNAP 20

/*
 * MINFREE gives the minimum acceptable percentage of file system
 * blocks which may be free. If the freelist drops below this level
 * only the superuser may continue to allocate blocks. This may
 * be set to 0 if no reserve of free blocks is deemed necessary,
 * however throughput drops by fifty percent if the file system
 * is run at between 95% and 100% full; thus the minimum default
 * value of fs_minfree is 5%. However, to get good clustering
 * performance, 10% is a better choice. hence we use 10% as our
 * default value. With 10% free space, fragmentation is not a
 * problem, so we choose to optimize for time.
 */
#define MINFREE     5
#define DEFAULTOPT  FS_OPTTIME

/*
 * Grigoriy Orlov <gluk@ptci.ru> has done some extensive work to fine
 * tune the layout preferences for directories within a filesystem.
 * His algorithm can be tuned by adjusting the following parameters
 * which tell the system the average file size and the average number
 * of files per directory. These defaults are well selected for typical
 * filesystems, but may need to be tuned for odd cases like filesystems
 * being used for squid caches or news spools.
 */
#define AVFILESIZ   16384   /* expected average file size */
#define AFPDIR      64  /* expected number of files per directory */

/*
 * Per cylinder group information; summarized in blocks allocated
 * from first cylinder group data blocks.  These blocks have to be
 * read in from fs_csaddr (size fs_cssize) in addition to the
 * super block.
 */
struct csum {
    int32_t cs_ndir;        /* number of directories */
    int32_t cs_nbfree;      /* number of free blocks */
    int32_t cs_nifree;      /* number of free inodes */
    int32_t cs_nffree;      /* number of free frags */
};

struct csum_total {
    int64_t cs_ndir;        /* number of directories */
    int64_t cs_nbfree;      /* number of free blocks */
    int64_t cs_nifree;      /* number of free inodes */
    int64_t cs_nffree;      /* number of free frags */
    int64_t cs_spare[4];        /* future expansion */
};


/*
 * Super block for an FFS file system in memory.
 */
struct fs {
    int32_t  fs_firstfield;     /* historic file system linked list, */
    int32_t  fs_unused_1;       /*     used for incore super blocks */
    int32_t  fs_sblkno;     /* addr of super-block in filesys */
    int32_t  fs_cblkno;     /* offset of cyl-block in filesys */
    int32_t  fs_iblkno;     /* offset of inode-blocks in filesys */
    int32_t  fs_dblkno;     /* offset of first data after cg */
    int32_t  fs_old_cgoffset;   /* cylinder group offset in cylinder */
    int32_t  fs_old_cgmask;     /* used to calc mod fs_ntrak */
    int32_t  fs_old_time;       /* last time written */
    int32_t  fs_old_size;       /* number of blocks in fs */
    int32_t  fs_old_dsize;      /* number of data blocks in fs */
    int32_t  fs_ncg;        /* number of cylinder groups */
    int32_t  fs_bsize;      /* size of basic blocks in fs */
    int32_t  fs_fsize;      /* size of frag blocks in fs */
    int32_t  fs_frag;       /* number of frags in a block in fs */
/* these are configuration parameters */
    int32_t  fs_minfree;        /* minimum percentage of free blocks */
    int32_t  fs_old_rotdelay;   /* num of ms for optimal next block */
    int32_t  fs_old_rps;        /* disk revolutions per second */
/* these fields can be computed from the others */
    int32_t  fs_bmask;      /* ``blkoff'' calc of blk offsets */
    int32_t  fs_fmask;      /* ``fragoff'' calc of frag offsets */
    int32_t  fs_bshift;     /* ``lblkno'' calc of logical blkno */
    int32_t  fs_fshift;     /* ``numfrags'' calc number of frags */
/* these are configuration parameters */
    int32_t  fs_maxcontig;      /* max number of contiguous blks */
    int32_t  fs_maxbpg;     /* max number of blks per cyl group */
/* these fields can be computed from the others */
    int32_t  fs_fragshift;      /* block to frag shift */
    int32_t  fs_fsbtodb;        /* fsbtodb and dbtofsb shift constant */
    int32_t  fs_sbsize;     /* actual size of super block */
    int32_t  fs_spare1[2];      /* old fs_csmask */
                    /* old fs_csshift */
    int32_t  fs_nindir;     /* value of NINDIR */
    int32_t  fs_inopb;      /* value of INOPB */
    int32_t  fs_old_nspf;       /* value of NSPF */
/* yet another configuration parameter */
    int32_t  fs_optim;      /* optimization preference, see below */
/* these fields are derived from the hardware */
    int32_t  fs_old_npsect;     /* # sectors/track including spares */
    int32_t  fs_old_interleave; /* hardware sector interleave */
    int32_t  fs_old_trackskew;  /* sector 0 skew, per track */
/* fs_id takes the space of the unused fs_headswitch and fs_trkseek fields */
    int32_t  fs_id[2];      /* unique file system id */
/* sizes determined by number of cylinder groups and their sizes */
    int32_t  fs_old_csaddr;     /* blk addr of cyl grp summary area */
    int32_t  fs_cssize;     /* size of cyl grp summary area */
    int32_t  fs_cgsize;     /* cylinder group size */
/* these fields are derived from the hardware */
    int32_t  fs_spare2;     /* old fs_ntrak */
    int32_t  fs_old_nsect;      /* sectors per track */
    int32_t  fs_old_spc;        /* sectors per cylinder */
    int32_t  fs_old_ncyl;       /* cylinders in file system */
    int32_t  fs_old_cpg;        /* cylinders per group */
    int32_t  fs_ipg;        /* inodes per group */
    int32_t  fs_fpg;        /* blocks per group * fs_frag */
/* this data must be re-computed after crashes */
    struct  csum fs_old_cstotal;    /* cylinder summary information */
/* these fields are cleared at mount time */
    int8_t   fs_fmod;       /* super block modified flag */
    int8_t   fs_clean;      /* file system is clean flag */
    int8_t   fs_ronly;      /* mounted read-only flag */
    uint8_t  fs_old_flags;      /* see FS_ flags below */
    u_char   fs_fsmnt[MAXMNTLEN];   /* name mounted on */
    u_char   fs_volname[MAXVOLLEN]; /* volume name */
    uint64_t fs_swuid;      /* system-wide uid */
    int32_t  fs_pad;
/* these fields retain the current block allocation info */
    int32_t  fs_cgrotor;        /* last cg searched (UNUSED) */
    void    *fs_ocsp[NOCSPTRS]; /* padding; was list of fs_cs buffers */
    u_int8_t *fs_contigdirs;    /* # of contiguously allocated dirs */
    struct csum *fs_csp;        /* cg summary info buffer for fs_cs */
    int32_t *fs_maxcluster;     /* max cluster in each cyl group */
    u_int   *fs_active;     /* used by snapshots to track fs */
    int32_t  fs_old_cpc;        /* cyl per cycle in postbl */
/* this area is otherwise allocated unless fs_old_flags & FS_FLAGS_UPDATED */
    int32_t  fs_maxbsize;       /* maximum blocking factor permitted */
    int64_t  fs_sparecon64[17]; /* old rotation block list head */
    int64_t  fs_sblockloc;      /* byte offset of standard superblock */
    struct  csum_total fs_cstotal;  /* cylinder summary information */
    int64_t  fs_time;       /* last time written */
    int64_t  fs_size;       /* number of blocks in fs */
    int64_t  fs_dsize;      /* number of data blocks in fs */
    int64_t  fs_csaddr;     /* blk addr of cyl grp summary area */
    int64_t  fs_pendingblocks;  /* blocks in process of being freed */
    int32_t  fs_pendinginodes;  /* inodes in process of being freed */
    int32_t  fs_snapinum[FSMAXSNAP];/* list of snapshot inode numbers */
/* back to stuff that has been around a while */
    int32_t  fs_avgfilesize;    /* expected average file size */
    int32_t  fs_avgfpdir;       /* expected # of files per directory */
    int32_t  fs_save_cgsize;    /* save real cg size to use fs_bsize */
    int32_t  fs_sparecon32[26]; /* reserved for future constants */
    uint32_t fs_flags;      /* see FS_ flags below */
/* back to stuff that has been around a while (again) */
    int32_t  fs_contigsumsize;  /* size of cluster summary array */ 
    int32_t  fs_maxsymlinklen;  /* max length of an internal symlink */
    int32_t  fs_old_inodefmt;   /* format of on-disk inodes */
    u_int64_t fs_maxfilesize;   /* maximum representable file size */
    int64_t  fs_qbmask;     /* ~fs_bmask for use with 64-bit size */
    int64_t  fs_qfmask;     /* ~fs_fmask for use with 64-bit size */
    int32_t  fs_state;      /* validate fs_clean field (UNUSED) */
    int32_t  fs_old_postblformat;   /* format of positional layout tables */
    int32_t  fs_old_nrpos;      /* number of rotational positions */
    int32_t  fs_spare5[2];      /* old fs_postbloff */
                    /* old fs_rotbloff */
    int32_t  fs_magic;      /* magic number */
};

#define fs_old_postbloff    fs_spare5[0]
#define fs_old_rotbloff     fs_spare5[1]
#define fs_old_postbl_start fs_maxbsize
#define fs_old_headswitch   fs_id[0]
#define fs_old_trkseek  fs_id[1]
#define fs_old_csmask   fs_spare1[0]
#define fs_old_csshift  fs_spare1[1]

#define FS_42POSTBLFMT      -1  /* 4.2BSD rotational table format */
#define FS_DYNAMICPOSTBLFMT 1   /* dynamic rotational table format */

#define old_fs_postbl(fs_, cylno, opostblsave) \
    ((((fs_)->fs_old_postblformat == FS_42POSTBLFMT) || \
     ((fs_)->fs_old_postbloff == offsetof(struct fs, fs_old_postbl_start))) \
    ? ((int16_t *)(opostblsave) + (cylno) * (fs_)->fs_old_nrpos) \
    : ((int16_t *)((uint8_t *)(fs_) + \
    (fs_)->fs_old_postbloff) + (cylno) * (fs_)->fs_old_nrpos))
#define old_fs_rotbl(fs) \
    (((fs)->fs_old_postblformat == FS_42POSTBLFMT) \
    ? ((uint8_t *)(&(fs)->fs_magic+1)) \
    : ((uint8_t *)((uint8_t *)(fs) + (fs)->fs_old_rotbloff)))

/*
 * File system identification
 */
#define FS_UFS1_MAGIC   0x011954    /* UFS1 fast file system magic number */
#define FS_UFS2_MAGIC   0x19540119  /* UFS2 fast file system magic number */
#define FS_UFS1_MAGIC_SWAPPED   0x54190100
#define FS_UFS2_MAGIC_SWAPPED   0x19015419
#define FS_OKAY     0x7c269d38  /* superblock checksum */
#define FS_42INODEFMT   -1      /* 4.2BSD inode format */
#define FS_44INODEFMT   2       /* 4.4BSD inode format */

/*
 * File system clean flags
 */
#define FS_ISCLEAN  0x01
#define FS_WASCLEAN 0x02

/*
 * Preference for optimization.
 */
#define FS_OPTTIME  0   /* minimize allocation time */
#define FS_OPTSPACE 1   /* minimize disk fragmentation */

/*
 * File system flags
 */
#define FS_UNCLEAN  0x01    /* file system not clean at mount (unused) */
#define FS_DOSOFTDEP    0x02    /* file system using soft dependencies */
#define FS_NEEDSFSCK    0x04    /* needs sync fsck (FreeBSD compat, unused) */
#define FS_INDEXDIRS    0x08    /* kernel supports indexed directories */
#define FS_ACLS     0x10    /* file system has ACLs enabled */
#define FS_MULTILABEL   0x20    /* file system is MAC multi-label */
#define FS_FLAGS_UPDATED 0x80   /* flags have been moved to new location */

/*
 * File system internal flags, also in fs_flags.
 * (Pick highest number to avoid conflicts with others)
 */
#define FS_SWAPPED  0x80000000  /* file system is endian swapped */
#define FS_INTERNAL 0x80000000  /* mask for internal flags */

/*
 * The size of a cylinder group is calculated by CGSIZE. The maximum size
 * is limited by the fact that cylinder groups are at most one block.
 * Its size is derived from the size of the maps maintained in the
 * cylinder group and the (struct cg) size.
 */
#define CGSIZE_IF(fs, ipg, fpg) \
    /* base cg */   (sizeof(struct cg) + sizeof(int32_t) + \
    /* old btotoff */   (fs)->fs_old_cpg * sizeof(int32_t) + \
    /* old boff */  (fs)->fs_old_cpg * sizeof(u_int16_t) + \
    /* inode map */ howmany((ipg), NBBY) + \
    /* block map */ howmany((fpg), NBBY) +\
    /* if present */    ((fs)->fs_contigsumsize <= 0 ? 0 : \
    /* cluster sum */   (fs)->fs_contigsumsize * sizeof(int32_t) + \
    /* cluster map */   howmany(fragstoblks(fs, (fpg)), NBBY)))

#define CGSIZE(fs) CGSIZE_IF((fs), (fs)->fs_ipg, (fs)->fs_fpg)

/*
 * The minimal number of cylinder groups that should be created.
 */
#define MINCYLGRPS  4


/*
 * Convert cylinder group to base address of its global summary info.
 */
#define fs_cs(fs, indx) fs_csp[indx]

/*
 * Cylinder group block for a file system.
 */
#define CG_MAGIC    0x090255
struct cg {
    int32_t  cg_firstfield;     /* historic cyl groups linked list */
    int32_t  cg_magic;      /* magic number */
    int32_t  cg_old_time;       /* time last written */
    int32_t  cg_cgx;        /* we are the cgx'th cylinder group */
    int16_t  cg_old_ncyl;       /* number of cyl's this cg */
    int16_t  cg_old_niblk;      /* number of inode blocks this cg */
    int32_t  cg_ndblk;      /* number of data blocks this cg */
    struct  csum cg_cs;     /* cylinder summary information */
    int32_t  cg_rotor;      /* position of last used block */
    int32_t  cg_frotor;     /* position of last used frag */
    int32_t  cg_irotor;     /* position of last used inode */
    int32_t  cg_frsum[MAXFRAG]; /* counts of available frags */
    int32_t  cg_old_btotoff;    /* (int32) block totals per cylinder */
    int32_t  cg_old_boff;       /* (u_int16) free block positions */
    int32_t  cg_iusedoff;       /* (u_int8) used inode map */
    int32_t  cg_freeoff;        /* (u_int8) free block map */
    int32_t  cg_nextfreeoff;    /* (u_int8) next available space */
    int32_t  cg_clustersumoff;  /* (u_int32) counts of avail clusters */
    int32_t  cg_clusteroff;     /* (u_int8) free cluster map */
    int32_t  cg_nclusterblks;   /* number of clusters this cg */
    int32_t  cg_niblk;      /* number of inode blocks this cg */
    int32_t  cg_initediblk;     /* last initialized inode */
    int32_t  cg_sparecon32[3];  /* reserved for future use */
    int64_t  cg_time;       /* time last written */
    int64_t  cg_sparecon64[3];  /* reserved for future use */
    u_int8_t cg_space[1];       /* space for cylinder group maps */
/* actually longer */
};

/*
 * The following structure is defined
 * for compatibility with old file systems.
 */
struct ocg {
    int32_t  cg_firstfield;     /* historic linked list of cyl groups */
    int32_t  cg_unused_1;       /*     used for incore cyl groups */
    int32_t  cg_time;       /* time last written */
    int32_t  cg_cgx;        /* we are the cgx'th cylinder group */
    int16_t  cg_ncyl;       /* number of cyl's this cg */
    int16_t  cg_niblk;      /* number of inode blocks this cg */
    int32_t  cg_ndblk;      /* number of data blocks this cg */
    struct  csum cg_cs;     /* cylinder summary information */
    int32_t  cg_rotor;      /* position of last used block */
    int32_t  cg_frotor;     /* position of last used frag */
    int32_t  cg_irotor;     /* position of last used inode */
    int32_t  cg_frsum[8];       /* counts of available frags */
    int32_t  cg_btot[32];       /* block totals per cylinder */
    int16_t  cg_b[32][8];       /* positions of free blocks */
    u_int8_t cg_iused[256];     /* used inode map */
    int32_t  cg_magic;      /* magic number */
    u_int8_t cg_free[1];        /* free block map */
/* actually longer */
};


/*
 * Macros for access to cylinder group array structures.
 */
#define old_cg_blktot_old(cgp, ns) \
    (((struct ocg *)(cgp))->cg_btot)
#define old_cg_blks_old(fs, cgp, cylno, ns) \
    (((struct ocg *)(cgp))->cg_b[cylno])

#define old_cg_blktot_new(cgp, ns) \
    ((int32_t *)((u_int8_t *)(cgp) + \
    ufs_rw32((cgp)->cg_old_btotoff, (ns))))
#define old_cg_blks_new(fs, cgp, cylno, ns) \
    ((int16_t *)((u_int8_t *)(cgp) + \
    ufs_rw32((cgp)->cg_old_boff, (ns))) + (cylno) * (fs)->fs_old_nrpos)

#define old_cg_blktot(cgp, ns) \
    ((ufs_rw32((cgp)->cg_magic, (ns)) != CG_MAGIC) ? \
      old_cg_blktot_old(cgp, ns) : old_cg_blktot_new(cgp, ns))
#define old_cg_blks(fs, cgp, cylno, ns) \
    ((ufs_rw32((cgp)->cg_magic, (ns)) != CG_MAGIC) ? \
      old_cg_blks_old(fs, cgp, cylno, ns) : old_cg_blks_new(fs, cgp, cylno, ns))

#define cg_inosused_new(cgp, ns) \
    ((u_int8_t *)((u_int8_t *)(cgp) + \
    ufs_rw32((cgp)->cg_iusedoff, (ns))))
#define cg_blksfree_new(cgp, ns) \
    ((u_int8_t *)((u_int8_t *)(cgp) + \
    ufs_rw32((cgp)->cg_freeoff, (ns))))
#define cg_chkmagic_new(cgp, ns) \
    (ufs_rw32((cgp)->cg_magic, (ns)) == CG_MAGIC)

#define cg_inosused_old(cgp, ns) \
    (((struct ocg *)(cgp))->cg_iused)
#define cg_blksfree_old(cgp, ns) \
    (((struct ocg *)(cgp))->cg_free)
#define cg_chkmagic_old(cgp, ns) \
    (ufs_rw32(((struct ocg *)(cgp))->cg_magic, (ns)) == CG_MAGIC)

#define cg_inosused(cgp, ns) \
    ((ufs_rw32((cgp)->cg_magic, (ns)) != CG_MAGIC) ? \
      cg_inosused_old(cgp, ns) : cg_inosused_new(cgp, ns))
#define cg_blksfree(cgp, ns) \
    ((ufs_rw32((cgp)->cg_magic, (ns)) != CG_MAGIC) ? \
      cg_blksfree_old(cgp, ns) : cg_blksfree_new(cgp, ns))
#define cg_chkmagic(cgp, ns) \
    (cg_chkmagic_new(cgp, ns) || cg_chkmagic_old(cgp, ns))

#define cg_clustersfree(cgp, ns) \
    ((u_int8_t *)((u_int8_t *)(cgp) + \
    ufs_rw32((cgp)->cg_clusteroff, (ns))))
#define cg_clustersum(cgp, ns) \
    ((int32_t *)((u_int8_t *)(cgp) + \
    ufs_rw32((cgp)->cg_clustersumoff, (ns))))
    

/*
 * Turn file system block numbers into disk block addresses.
 * This maps file system blocks to device size blocks.
 */
#define fsbtodb(fs, b)  ((b) << (fs)->fs_fsbtodb)
#define dbtofsb(fs, b)  ((b) >> (fs)->fs_fsbtodb)

/*
 * Cylinder group macros to locate things in cylinder groups.
 * They calc file system addresses of cylinder group data structures.
 */
#define cgbase(fs, c)   (((daddr_t)(fs)->fs_fpg) * (c))
#define cgstart_ufs1(fs, c) \
    (cgbase(fs, c) + (fs)->fs_old_cgoffset * ((c) & ~((fs)->fs_old_cgmask)))
#define cgstart_ufs2(fs, c) cgbase((fs), (c))
#define cgstart(fs, c) ((fs)->fs_magic == FS_UFS2_MAGIC \
                ? cgstart_ufs2((fs), (c)) : cgstart_ufs1((fs), (c)))
#define cgdmin(fs, c)   (cgstart(fs, c) + (fs)->fs_dblkno)  /* 1st data */
#define cgimin(fs, c)   (cgstart(fs, c) + (fs)->fs_iblkno)  /* inode blk */
#define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno)  /* super blk */
#define cgtod(fs, c)    (cgstart(fs, c) + (fs)->fs_cblkno)  /* cg block */

/*
 * Macros for handling inode numbers:
 *     inode number to file system block offset.
 *     inode number to cylinder group number.
 *     inode number to file system block address.
 */
#define ino_to_cg(fs, x)    ((x) / (fs)->fs_ipg)
#define ino_to_fsba(fs, x)                      \
    ((daddr_t)(cgimin(fs, ino_to_cg(fs, x)) +           \
        (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
#define ino_to_fsbo(fs, x)  ((x) % INOPB(fs))

/*
 * Give cylinder group number for a file system block.
 * Give cylinder group block number for a file system block.
 */
#define dtog(fs, d) ((d) / (fs)->fs_fpg)
#define dtogd(fs, d)    ((d) % (fs)->fs_fpg)

/*
 * Extract the bits for a block from a map.
 * Compute the cylinder and rotational position of a cyl block addr.
 */
#define blkmap(fs, map, loc) \
    (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
#define old_cbtocylno(fs, bno) \
    (fsbtodb(fs, bno) / (fs)->fs_old_spc)
#define old_cbtorpos(fs, bno) \
    ((fs)->fs_old_nrpos <= 1 ? 0 : \
     (fsbtodb(fs, bno) % (fs)->fs_old_spc / (fs)->fs_old_nsect * (fs)->fs_old_trackskew + \
      fsbtodb(fs, bno) % (fs)->fs_old_spc % (fs)->fs_old_nsect * (fs)->fs_old_interleave) % \
     (fs)->fs_old_nsect * (fs)->fs_old_nrpos / (fs)->fs_old_npsect)

/*
 * The following macros optimize certain frequently calculated
 * quantities by using shifts and masks in place of divisions
 * modulos and multiplications.
 */
#define blkoff(fs, loc)     /* calculates (loc % fs->fs_bsize) */ \
    ((loc) & (fs)->fs_qbmask)
#define fragoff(fs, loc)    /* calculates (loc % fs->fs_fsize) */ \
    ((loc) & (fs)->fs_qfmask)
#define lfragtosize(fs, frag)   /* calculates ((off_t)frag * fs->fs_fsize) */ \
    (((off_t)(frag)) << (fs)->fs_fshift)
#define lblktosize(fs, blk) /* calculates ((off_t)blk * fs->fs_bsize) */ \
    (((off_t)(blk)) << (fs)->fs_bshift)
#define lblkno(fs, loc)     /* calculates (loc / fs->fs_bsize) */ \
    ((loc) >> (fs)->fs_bshift)
#define numfrags(fs, loc)   /* calculates (loc / fs->fs_fsize) */ \
    ((loc) >> (fs)->fs_fshift)
#define blkroundup(fs, size)    /* calculates roundup(size, fs->fs_bsize) */ \
    (((size) + (fs)->fs_qbmask) & (fs)->fs_bmask)
#define fragroundup(fs, size)   /* calculates roundup(size, fs->fs_fsize) */ \
    (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask)
#define fragstoblks(fs, frags)  /* calculates (frags / fs->fs_frag) */ \
    ((frags) >> (fs)->fs_fragshift)
#define blkstofrags(fs, blks)   /* calculates (blks * fs->fs_frag) */ \
    ((blks) << (fs)->fs_fragshift)
#define fragnum(fs, fsb)    /* calculates (fsb % fs->fs_frag) */ \
    ((fsb) & ((fs)->fs_frag - 1))
#define blknum(fs, fsb)     /* calculates rounddown(fsb, fs->fs_frag) */ \
    ((fsb) &~ ((fs)->fs_frag - 1))

/*
 * Determine the number of available frags given a
 * percentage to hold in reserve.
 */
#define freespace(fs, percentreserved) \
    (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
    (fs)->fs_cstotal.cs_nffree - \
    (((off_t)((fs)->fs_dsize)) * (percentreserved) / 100))

/*
 * Determining the size of a file block in the file system.
 */
#define blksize(fs, ip, lbn) \
    (((lbn) >= NDADDR || (ip)->i_size >= lblktosize(fs, (lbn) + 1)) \
        ? (fs)->fs_bsize \
        : (fragroundup(fs, blkoff(fs, (ip)->i_size))))

#define sblksize(fs, size, lbn) \
    (((lbn) >= NDADDR || (size) >= ((lbn) + 1) << (fs)->fs_bshift) \
      ? (fs)->fs_bsize \
      : (fragroundup(fs, blkoff(fs, (size)))))


/*
 * Number of inodes in a secondary storage block/fragment.
 */
#define INOPB(fs)   ((fs)->fs_inopb)
#define INOPF(fs)   ((fs)->fs_inopb >> (fs)->fs_fragshift)

/*
 * Number of indirects in a file system block.
 */
#define NINDIR(fs)  ((fs)->fs_nindir)

/*
 * Apple UFS Label:
 *  We check for this to decide to use APPLEUFS_DIRBLKSIZ
 */
#define APPLEUFS_LABEL_MAGIC        0x4c41424c /* LABL */
#define APPLEUFS_LABEL_SIZE     1024
#define APPLEUFS_LABEL_OFFSET   (BBSIZE - APPLEUFS_LABEL_SIZE) /* located at 7k */
#define APPLEUFS_LABEL_VERSION  1
#define APPLEUFS_MAX_LABEL_NAME 512

#if 0
struct appleufslabel {
    u_int32_t   ul_magic;
    u_int16_t   ul_checksum;
    u_int16_t   ul_unused0;
    u_int32_t   ul_version;
    u_int32_t   ul_time;
    u_int16_t   ul_namelen;
    u_char  ul_name[APPLEUFS_MAX_LABEL_NAME]; /* Warning: may not be null terminated */
    u_int16_t   ul_unused1;
    u_int64_t   ul_uuid;    /* Note this is only 4 byte aligned */
    u_char  ul_reserved[24];
    u_char  ul_unused[460];
} __attribute__((__packed__));
#endif


#endif /* !_UFS_FFS_FS_H_ */