bsd/ufs/ffs/fs.h

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  26 /*
  27  * Copyright (c) 1982, 1986, 1993
  28  *      The Regents of the University of California.  All rights reserved.
  29  *
  30  * Redistribution and use in source and binary forms, with or without
  31  * modification, are permitted provided that the following conditions
  32  * are met:
  33  * 1. Redistributions of source code must retain the above copyright
  34  *    notice, this list of conditions and the following disclaimer.
  35  * 2. Redistributions in binary form must reproduce the above copyright
  36  *    notice, this list of conditions and the following disclaimer in the
  37  *    documentation and/or other materials provided with the distribution.
  38  * 3. All advertising materials mentioning features or use of this software
  39  *    must display the following acknowledgement:
  40  *      This product includes software developed by the University of
  41  *      California, Berkeley and its contributors.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  *
  58  *      @(#)fs.h        8.13 (Berkeley) 3/21/95
  59  */
  60 #ifndef _FFS_FS_H_
  61 #define _FFS_FS_H_
  62
  63 #include <sys/appleapiopts.h>
  64
  65 #ifdef __APPLE_API_UNSTABLE
  66 /*
  67  * Each disk drive contains some number of file systems.
  68  * A file system consists of a number of cylinder groups.
  69  * Each cylinder group has inodes and data.
  70  *
  71  * A file system is described by its super-block, which in turn
  72  * describes the cylinder groups.  The super-block is critical
  73  * data and is replicated in each cylinder group to protect against
  74  * catastrophic loss.  This is done at `newfs' time and the critical
  75  * super-block data does not change, so the copies need not be
  76  * referenced further unless disaster strikes.
  77  *
  78  * For file system fs, the offsets of the various blocks of interest
  79  * are given in the super block as:
  80  *      [fs->fs_sblkno]         Super-block
  81  *      [fs->fs_cblkno]         Cylinder group block
  82  *      [fs->fs_iblkno]         Inode blocks
  83  *      [fs->fs_dblkno]         Data blocks
  84  * The beginning of cylinder group cg in fs, is given by
  85  * the ``cgbase(fs, cg)'' macro.
  86  *
  87  * The first boot and super blocks are given in absolute disk addresses.
  88  * The byte-offset forms are preferred, as they don't imply a sector size.
  89  */
  90 #define BBSIZE          8192
  91 #define SBSIZE          8192
  92 #define BBOFF           ((off_t)(0))
  93 #define SBOFF           ((off_t)(BBOFF + BBSIZE))
  94 #define BBLOCK          ((ufs_daddr_t)(0))
  95 #define SBLOCK          ((ufs_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
  96
  97 /*
  98  * Addresses stored in inodes are capable of addressing fragments
  99  * of `blocks'. File system blocks of at most size MAXBSIZE can
 100  * be optionally broken into 2, 4, or 8 pieces, each of which is
 101  * addressible; these pieces may be DEV_BSIZE, or some multiple of
 102  * a DEV_BSIZE unit.
 103  *
 104  * Large files consist of exclusively large data blocks.  To avoid
 105  * undue wasted disk space, the last data block of a small file may be
 106  * allocated as only as many fragments of a large block as are
 107  * necessary.  The file system format retains only a single pointer
 108  * to such a fragment, which is a piece of a single large block that
 109  * has been divided.  The size of such a fragment is determinable from
 110  * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
 111  *
 112  * The file system records space availability at the fragment level;
 113  * to determine block availability, aligned fragments are examined.
 114  */
 115
 116 /*
 117  * MINBSIZE is the smallest allowable block size.
 118  * In order to insure that it is possible to create files of size
 119  * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
 120  * MINBSIZE must be big enough to hold a cylinder group block,
 121  * thus changes to (struct cg) must keep its size within MINBSIZE.
 122  * Note that super blocks are always of size SBSIZE,
 123  * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
 124  */
 125 #define MINBSIZE        4096
 126
 127 /*
 128  * The path name on which the file system is mounted is maintained
 129  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
 130  * the super block for this name.
 131  */
 132 #define MAXMNTLEN       512
 133
 134 /*
 135  * The limit on the amount of summary information per file system
 136  * is defined by MAXCSBUFS. It is currently parameterized for a
 137  * size of 128 bytes (2 million cylinder groups on machines with
 138  * 32-bit pointers, and 1 million on 64-bit machines). One pointer
 139  * is taken away to point to an array of cluster sizes that is
 140  * computed as cylinder groups are inspected.
 141  * There is a 128-byte region in the superblock reserved for in-core
 142  * pointers to summary information. Originally this included an array
 143  * of pointers to blocks of struct csum; now there are just two
 144  * pointers and the remaining space is padded with fs_ocsp[].
 145  *
 146  * NOCSPTRS determines the size of this padding. One pointer (fs_csp)
 147  * is taken away to point to a contiguous array of struct csum for
 148  * all cylinder groups; a second (fs_maxcluster) points to an array
 149  * of cluster sizes that is computed as cylinder groups are inspected.
 150  */
 151 #define NOCSPTRS ((128 / sizeof(void *)) - 2)
 152
 153
 154 /*
 155  * A summary of contiguous blocks of various sizes is maintained
 156  * in each cylinder group. Normally this is set by the initial
 157  * value of fs_maxcontig. To conserve space, a maximum summary size
 158  * is set by FS_MAXCONTIG.
 159  */
 160 #define FS_MAXCONTIG    16
 161
 162 /*
 163  * MINFREE gives the minimum acceptable percentage of file system
 164  * blocks which may be free. If the freelist drops below this level
 165  * only the superuser may continue to allocate blocks. This may
 166  * be set to 0 if no reserve of free blocks is deemed necessary,
 167  * however throughput drops by fifty percent if the file system
 168  * is run at between 95% and 100% full; thus the minimum default
 169  * value of fs_minfree is 5%. However, to get good clustering
 170  * performance, 10% is a better choice. hence we use 10% as our
 171  * default value. With 10% free space, fragmentation is not a
 172  * problem, so we choose to optimize for time.
 173  */
 174 #define MINFREE         5
 175 #define DEFAULTOPT      FS_OPTTIME
 176
 177 /*
 178  * Per cylinder group information; summarized in blocks allocated
 179  * from first cylinder group data blocks.  These blocks have to be
 180  * read in from fs_csaddr (size fs_cssize) in addition to the
 181  * super block.
 182  */
 183 struct csum {
 184         int32_t cs_ndir;                /* number of directories */
 185         int32_t cs_nbfree;              /* number of free blocks */
 186         int32_t cs_nifree;              /* number of free inodes */
 187         int32_t cs_nffree;              /* number of free frags */
 188 };
 189
 190 /*
 191  * Super block for an FFS file system.
 192  */
 193 struct fs {
 194         int32_t  fs_firstfield;         /* historic file system linked list, */
 195         int32_t  fs_unused_1;           /*     used for incore super blocks */
 196         ufs_daddr_t fs_sblkno;          /* addr of super-block in filesys */
 197         ufs_daddr_t fs_cblkno;          /* offset of cyl-block in filesys */
 198         ufs_daddr_t fs_iblkno;          /* offset of inode-blocks in filesys */
 199         ufs_daddr_t fs_dblkno;          /* offset of first data after cg */
 200         int32_t  fs_cgoffset;           /* cylinder group offset in cylinder */
 201         int32_t  fs_cgmask;             /* used to calc mod fs_ntrak */
 202         time_t   fs_time;               /* last time written */
 203         int32_t  fs_size;               /* number of blocks in fs */
 204         int32_t  fs_dsize;              /* number of data blocks in fs */
 205         int32_t  fs_ncg;                /* number of cylinder groups */
 206         int32_t  fs_bsize;              /* size of basic blocks in fs */
 207         int32_t  fs_fsize;              /* size of frag blocks in fs */
 208         int32_t  fs_frag;               /* number of frags in a block in fs */
 209 /* these are configuration parameters */
 210         int32_t  fs_minfree;            /* minimum percentage of free blocks */
 211         int32_t  fs_rotdelay;           /* num of ms for optimal next block */
 212         int32_t  fs_rps;                /* disk revolutions per second */
 213 /* these fields can be computed from the others */
 214         int32_t  fs_bmask;              /* ``blkoff'' calc of blk offsets */
 215         int32_t  fs_fmask;              /* ``fragoff'' calc of frag offsets */
 216         int32_t  fs_bshift;             /* ``lblkno'' calc of logical blkno */
 217         int32_t  fs_fshift;             /* ``numfrags'' calc number of frags */
 218 /* these are configuration parameters */
 219         int32_t  fs_maxcontig;          /* max number of contiguous blks */
 220         int32_t  fs_maxbpg;             /* max number of blks per cyl group */
 221 /* these fields can be computed from the others */
 222         int32_t  fs_fragshift;          /* block to frag shift */
 223         int32_t  fs_fsbtodb;            /* fsbtodb and dbtofsb shift constant */
 224         int32_t  fs_sbsize;             /* actual size of super block */
 225         int32_t  fs_csmask;             /* csum block offset (now unused) */
 226         int32_t  fs_csshift;            /* csum block number (now unused) */
 227         int32_t  fs_nindir;             /* value of NINDIR */
 228         int32_t  fs_inopb;              /* value of INOPB */
 229         int32_t  fs_nspf;               /* value of NSPF */
 230 /* yet another configuration parameter */
 231         int32_t  fs_optim;              /* optimization preference, see below */
 232 /* these fields are derived from the hardware */
 233         int32_t  fs_npsect;             /* # sectors/track including spares */
 234         int32_t  fs_interleave;         /* hardware sector interleave */
 235         int32_t  fs_trackskew;          /* sector 0 skew, per track */
 236         int32_t  fs_headswitch;         /* head switch time, usec */
 237         int32_t  fs_trkseek;            /* track-to-track seek, usec */
 238 /* sizes determined by number of cylinder groups and their sizes */
 239         ufs_daddr_t fs_csaddr;          /* blk addr of cyl grp summary area */
 240         int32_t  fs_cssize;             /* size of cyl grp summary area */
 241         int32_t  fs_cgsize;             /* cylinder group size */
 242 /* these fields are derived from the hardware */
 243         int32_t  fs_ntrak;              /* tracks per cylinder */
 244         int32_t  fs_nsect;              /* sectors per track */
 245         int32_t  fs_spc;                        /* sectors per cylinder */
 246 /* this comes from the disk driver partitioning */
 247         int32_t  fs_ncyl;               /* cylinders in file system */
 248 /* these fields can be computed from the others */
 249         int32_t  fs_cpg;                        /* cylinders per group */
 250         int32_t  fs_ipg;                        /* inodes per group */
 251         int32_t  fs_fpg;                        /* blocks per group * fs_frag */
 252 /* this data must be re-computed after crashes */
 253         struct  csum fs_cstotal;        /* cylinder summary information */
 254 /* these fields are cleared at mount time */
 255         int8_t   fs_fmod;               /* super block modified flag */
 256         int8_t   fs_clean;              /* file system is clean flag */
 257         int8_t   fs_ronly;              /* mounted read-only flag */
 258         int8_t   fs_flags;              /* currently unused flag */
 259         u_char   fs_fsmnt[MAXMNTLEN];   /* name mounted on */
 260 /* these fields retain the current block allocation info */
 261         int32_t  fs_cgrotor;            /* last cg searched */
 262         void    *fs_ocsp[NOCSPTRS];     /* list of fs_cs info buffers */
 263         struct  csum *fs_csp;           /* list of fs_cs info buffers */
 264         int32_t  *fs_maxcluster;        /* max cluster in each cyl group */
 265         int32_t  fs_cpc;                /* cyl per cycle in postbl */
 266         int16_t  fs_opostbl[16][8];     /* old rotation block list head */
 267         int32_t  fs_sparecon[50];       /* reserved for future constants */
 268         int32_t  fs_contigsumsize;      /* size of cluster summary array */
 269         int32_t  fs_maxsymlinklen;      /* max length of an internal symlink */
 270         int32_t  fs_inodefmt;           /* format of on-disk inodes */
 271         u_int64_t fs_maxfilesize;       /* maximum representable file size */
 272         int64_t  fs_qbmask;             /* ~fs_bmask for use with 64-bit size */
 273         int64_t  fs_qfmask;             /* ~fs_fmask for use with 64-bit size */
 274         int32_t  fs_state;              /* validate fs_clean field */
 275         int32_t  fs_postblformat;       /* format of positional layout tables */
 276         int32_t  fs_nrpos;              /* number of rotational positions */
 277         int32_t  fs_postbloff;          /* (u_int16) rotation block list head */
 278         int32_t  fs_rotbloff;           /* (u_int8) blocks for each rotation */
 279         int32_t  fs_magic;              /* magic number */
 280         u_int8_t fs_space[1];           /* list of blocks for each rotation */
 281 /* actually longer */
 282 };
 283
 284 /*
 285  * Filesystem identification
 286  */
 287 #define FS_MAGIC        0x011954        /* the fast filesystem magic number */
 288 #define FS_OKAY         0x7c269d38      /* superblock checksum */
 289 #define FS_42INODEFMT   -1              /* 4.2BSD inode format */
 290 #define FS_44INODEFMT   2               /* 4.4BSD inode format */
 291 /*
 292  * Preference for optimization.
 293  */
 294 #define FS_OPTTIME      0       /* minimize allocation time */
 295 #define FS_OPTSPACE     1       /* minimize disk fragmentation */
 296
 297 /*
 298  * Rotational layout table format types
 299  */
 300 #define FS_42POSTBLFMT          -1      /* 4.2BSD rotational table format */
 301 #define FS_DYNAMICPOSTBLFMT     1       /* dynamic rotational table format */
 302 /*
 303  * Macros for access to superblock array structures
 304  */
 305 #define fs_postbl(fs, cylno) \
 306     (((fs)->fs_postblformat == FS_42POSTBLFMT) \
 307     ? ((fs)->fs_opostbl[cylno]) \
 308     : ((int16_t *)((u_int8_t *)(fs) + \
 309         (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
 310 #define fs_rotbl(fs) \
 311     (((fs)->fs_postblformat == FS_42POSTBLFMT) \
 312     ? ((fs)->fs_space) \
 313     : ((u_int8_t *)((u_int8_t *)(fs) + (fs)->fs_rotbloff)))
 314
 315 /*
 316  * The size of a cylinder group is calculated by CGSIZE. The maximum size
 317  * is limited by the fact that cylinder groups are at most one block.
 318  * Its size is derived from the size of the maps maintained in the
 319  * cylinder group and the (struct cg) size.
 320  */
 321 #define CGSIZE(fs) \
 322     /* base cg */       (sizeof(struct cg) + sizeof(int32_t) + \
 323     /* blktot size */   (fs)->fs_cpg * sizeof(int32_t) + \
 324     /* blks size */     (fs)->fs_cpg * (fs)->fs_nrpos * sizeof(int16_t) + \
 325     /* inode map */     howmany((fs)->fs_ipg, NBBY) + \
 326     /* block map */     howmany((fs)->fs_cpg * (fs)->fs_spc / NSPF(fs), NBBY) +\
 327     /* if present */    ((fs)->fs_contigsumsize <= 0 ? 0 : \
 328     /* cluster sum */   (fs)->fs_contigsumsize * sizeof(int32_t) + \
 329     /* cluster map */   howmany((fs)->fs_cpg * (fs)->fs_spc / NSPB(fs), NBBY)))
 330
 331 /*
 332  * Convert cylinder group to base address of its global summary info.
 333  *
 334  * N.B. This macro assumes that sizeof(struct csum) is a power of two.
 335  */
 336 #define fs_cs(fs, indx) fs_csp[indx]
 337
 338 /*
 339  * Cylinder group block for a file system.
 340  */
 341 #define CG_MAGIC        0x090255
 342 struct cg {
 343         int32_t  cg_firstfield;         /* historic cyl groups linked list */
 344         int32_t  cg_magic;              /* magic number */
 345         time_t   cg_time;               /* time last written */
 346         int32_t  cg_cgx;                /* we are the cgx'th cylinder group */
 347         int16_t  cg_ncyl;               /* number of cyl's this cg */
 348         int16_t  cg_niblk;              /* number of inode blocks this cg */
 349         int32_t  cg_ndblk;              /* number of data blocks this cg */
 350         struct  csum cg_cs;             /* cylinder summary information */
 351         int32_t  cg_rotor;              /* position of last used block */
 352         int32_t  cg_frotor;             /* position of last used frag */
 353         int32_t  cg_irotor;             /* position of last used inode */
 354         int32_t  cg_frsum[MAXFRAG];     /* counts of available frags */
 355         int32_t  cg_btotoff;            /* (int32) block totals per cylinder */
 356         int32_t  cg_boff;               /* (u_int16) free block positions */
 357         int32_t  cg_iusedoff;           /* (u_int8) used inode map */
 358         int32_t  cg_freeoff;            /* (u_int8) free block map */
 359         int32_t  cg_nextfreeoff;        /* (u_int8) next available space */
 360         int32_t  cg_clustersumoff;      /* (u_int32) counts of avail clusters */
 361         int32_t  cg_clusteroff;         /* (u_int8) free cluster map */
 362         int32_t  cg_nclusterblks;       /* number of clusters this cg */
 363         int32_t  cg_sparecon[13];       /* reserved for future use */
 364         u_int8_t cg_space[1];           /* space for cylinder group maps */
 365 /* actually longer */
 366 };
 367
 368 /*
 369  * Macros for access to cylinder group array structures
 370  */
 371 #define cg_blktot(cgp) \
 372     (((cgp)->cg_magic != CG_MAGIC) \
 373     ? (((struct ocg *)(cgp))->cg_btot) \
 374     : ((int32_t *)((u_int8_t *)(cgp) + (cgp)->cg_btotoff)))
 375 #define cg_blks(fs, cgp, cylno) \
 376     (((cgp)->cg_magic != CG_MAGIC) \
 377     ? (((struct ocg *)(cgp))->cg_b[cylno]) \
 378     : ((int16_t *)((u_int8_t *)(cgp) + \
 379         (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
 380 #define cg_inosused(cgp) \
 381     (((cgp)->cg_magic != CG_MAGIC) \
 382     ? (((struct ocg *)(cgp))->cg_iused) \
 383     : ((u_int8_t *)((u_int8_t *)(cgp) + (cgp)->cg_iusedoff)))
 384 #define cg_blksfree(cgp) \
 385     (((cgp)->cg_magic != CG_MAGIC) \
 386     ? (((struct ocg *)(cgp))->cg_free) \
 387     : ((u_int8_t *)((u_int8_t *)(cgp) + (cgp)->cg_freeoff)))
 388 #define cg_chkmagic(cgp) \
 389     ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
 390 #define cg_clustersfree(cgp) \
 391     ((u_int8_t *)((u_int8_t *)(cgp) + (cgp)->cg_clusteroff))
 392 #define cg_clustersum(cgp) \
 393     ((int32_t *)((u_int8_t *)(cgp) + (cgp)->cg_clustersumoff))
 394
 395 /*
 396  * The following structure is defined
 397  * for compatibility with old file systems.
 398  */
 399 struct ocg {
 400         int32_t  cg_firstfield;         /* historic linked list of cyl groups */
 401         int32_t  cg_unused_1;           /*     used for incore cyl groups */
 402         time_t   cg_time;               /* time last written */
 403         int32_t  cg_cgx;                /* we are the cgx'th cylinder group */
 404         int16_t  cg_ncyl;               /* number of cyl's this cg */
 405         int16_t  cg_niblk;              /* number of inode blocks this cg */
 406         int32_t  cg_ndblk;              /* number of data blocks this cg */
 407         struct  csum cg_cs;             /* cylinder summary information */
 408         int32_t  cg_rotor;              /* position of last used block */
 409         int32_t  cg_frotor;             /* position of last used frag */
 410         int32_t  cg_irotor;             /* position of last used inode */
 411         int32_t  cg_frsum[8];           /* counts of available frags */
 412         int32_t  cg_btot[32];           /* block totals per cylinder */
 413         int16_t  cg_b[32][8];           /* positions of free blocks */
 414         u_int8_t cg_iused[256];         /* used inode map */
 415         int32_t  cg_magic;              /* magic number */
 416         u_int8_t cg_free[1];            /* free block map */
 417 /* actually longer */
 418 };
 419
 420 /*
 421  * Turn file system block numbers into disk block addresses.
 422  * This maps file system blocks to device size blocks.
 423  */
 424 #define fsbtodb(fs, b)  ((b) << (fs)->fs_fsbtodb)
 425 #define dbtofsb(fs, b)  ((b) >> (fs)->fs_fsbtodb)
 426
 427 /*
 428  * Cylinder group macros to locate things in cylinder groups.
 429  * They calc file system addresses of cylinder group data structures.
 430  */
 431 #define cgbase(fs, c)   ((ufs_daddr_t)((fs)->fs_fpg * (c)))
 432 #define cgdmin(fs, c)   (cgstart(fs, c) + (fs)->fs_dblkno)      /* 1st data */
 433 #define cgimin(fs, c)   (cgstart(fs, c) + (fs)->fs_iblkno)      /* inode blk */
 434 #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno)      /* super blk */
 435 #define cgtod(fs, c)    (cgstart(fs, c) + (fs)->fs_cblkno)      /* cg block */
 436 #define cgstart(fs, c)                                                  \
 437         (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
 438
 439 /*
 440  * Macros for handling inode numbers:
 441  *     inode number to file system block offset.
 442  *     inode number to cylinder group number.
 443  *     inode number to file system block address.
 444  */
 445 #define ino_to_cg(fs, x)        ((x) / (fs)->fs_ipg)
 446 #define ino_to_fsba(fs, x)                                              \
 447         ((ufs_daddr_t)(cgimin(fs, ino_to_cg(fs, x)) +                   \
 448             (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
 449 #define ino_to_fsbo(fs, x)      ((x) % INOPB(fs))
 450
 451 /*
 452  * Give cylinder group number for a file system block.
 453  * Give cylinder group block number for a file system block.
 454  */
 455 #define dtog(fs, d)     ((d) / (fs)->fs_fpg)
 456 #define dtogd(fs, d)    ((d) % (fs)->fs_fpg)
 457
 458 /*
 459  * Extract the bits for a block from a map.
 460  * Compute the cylinder and rotational position of a cyl block addr.
 461  */
 462 #define blkmap(fs, map, loc) \
 463     (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
 464 #define cbtocylno(fs, bno) \
 465     ((bno) * NSPF(fs) / (fs)->fs_spc)
 466 #define cbtorpos(fs, bno) \
 467     (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
 468      (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
 469      (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
 470
 471 /*
 472  * The following macros optimize certain frequently calculated
 473  * quantities by using shifts and masks in place of divisions
 474  * modulos and multiplications.
 475  */
 476 #define blkoff(fs, loc)         /* calculates (loc % fs->fs_bsize) */ \
 477         ((loc) & (fs)->fs_qbmask)
 478 #define fragoff(fs, loc)        /* calculates (loc % fs->fs_fsize) */ \
 479         ((loc) & (fs)->fs_qfmask)
 480 #define lblktosize(fs, blk)     /* calculates (blk * fs->fs_bsize) */ \
 481         ((blk) << (fs)->fs_bshift)
 482 #define lblkno(fs, loc)         /* calculates (loc / fs->fs_bsize) */ \
 483         ((loc) >> (fs)->fs_bshift)
 484 #define numfrags(fs, loc)       /* calculates (loc / fs->fs_fsize) */ \
 485         ((loc) >> (fs)->fs_fshift)
 486 #define blkroundup(fs, size)    /* calculates roundup(size, fs->fs_bsize) */ \
 487         (((size) + (fs)->fs_qbmask) & (fs)->fs_bmask)
 488 #define fragroundup(fs, size)   /* calculates roundup(size, fs->fs_fsize) */ \
 489         (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask)
 490 #define fragstoblks(fs, frags)  /* calculates (frags / fs->fs_frag) */ \
 491         ((frags) >> (fs)->fs_fragshift)
 492 #define blkstofrags(fs, blks)   /* calculates (blks * fs->fs_frag) */ \
 493         ((blks) << (fs)->fs_fragshift)
 494 #define fragnum(fs, fsb)        /* calculates (fsb % fs->fs_frag) */ \
 495         ((fsb) & ((fs)->fs_frag - 1))
 496 #define blknum(fs, fsb)         /* calculates rounddown(fsb, fs->fs_frag) */ \
 497         ((fsb) &~ ((fs)->fs_frag - 1))
 498
 499 /*
 500  * Determine the number of available frags given a
 501  * percentage to hold in reserve.
 502  */
 503 #define freespace(fs, percentreserved) \
 504         (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
 505         (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
 506
 507 /*
 508  * Determining the size of a file block in the file system.
 509  */
 510 #define blksize(fs, ip, lbn) \
 511         (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
 512             ? (fs)->fs_bsize \
 513             : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
 514 #define dblksize(fs, dip, lbn) \
 515         (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
 516             ? (fs)->fs_bsize \
 517             : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
 518
 519 /*
 520  * Number of disk sectors per block/fragment; assumes DEV_BSIZE byte
 521  * sector size.
 522  */
 523 #define NSPB(fs)        ((fs)->fs_nspf << (fs)->fs_fragshift)
 524 #define NSPF(fs)        ((fs)->fs_nspf)
 525
 526 /*
 527  * Number of inodes in a secondary storage block/fragment.
 528  */
 529 #define INOPB(fs)       ((fs)->fs_inopb)
 530 #define INOPF(fs)       ((fs)->fs_inopb >> (fs)->fs_fragshift)
 531
 532 /*
 533  * Number of indirects in a file system block.
 534  */
 535 #define NINDIR(fs)      ((fs)->fs_nindir)
 536
 537 /*
 538  * This macro controls whether the file system format is byte swapped or not.
 539  * At NeXT, all little endian machines read and write big endian file systems.
 540  */
 541 #define BIG_ENDIAN_FS   (__LITTLE_ENDIAN__)
 542
 543 #ifdef __APPLE_API_PRIVATE
 544 extern int inside[], around[];
 545 extern u_char *fragtbl[];
 546 #endif /* __APPLE_API_PRIVATE */
 547
 548
 549 /*
 550  * UFS Label:
 551  *   The purpose of this label is to name a UFS/FFS filesystem.  The label
 552  *   is located at offset 7K (BBSIZE=8K - UFS_LABEL_SIZE=1K = 7K) of the
 553  *   partition.  The first 7K is still available for boot blocks.
 554  */
 555
 556 #define UFS_LABEL_MAGIC         { 'L', 'A', 'B', 'L' }
 557 #define UFS_LABEL_SIZE          1024
 558 #define UFS_LABEL_OFFSET        (BBSIZE - UFS_LABEL_SIZE) /* top 1K */
 559 #define UFS_LABEL_VERSION       1
 560 #define UFS_MAX_LABEL_NAME      512
 561
 562 struct ufslabel {
 563     u_int32_t           ul_magic;
 564     u_int16_t           ul_checksum;    /* checksum over entire label*/
 565     u_int32_t           ul_version;     /* label version */
 566     u_int32_t           ul_time;        /* creation time */
 567     u_int16_t           ul_namelen;     /* filesystem name length */
 568     u_char              ul_name[UFS_MAX_LABEL_NAME]; /* filesystem name */
 569     u_int64_t           ul_uuid;        /* filesystem uuid */
 570     u_char              ul_reserved[24];/* reserved for future use */
 571     u_char              ul_unused[460]; /* pad out to 1K */
 572 };
 573
 574 #endif /* __APPLE_API_UNSTABLE */
 575 #endif /* ! _FFS_FS_H_ */