bootx.tproj/fs.subproj/ext2fs.h

   1 /*
   2  * Copyright (c) 2000 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 /*      $NetBSD: ext2fs.h,v 1.10 2000/01/28 16:00:23 bouyer Exp $       */
  26 /*
  27  * Copyright (c) 1997 Manuel Bouyer.
  28  * Copyright (c) 1982, 1986, 1993
  29  *      The Regents of the University of California.  All rights reserved.
  30  *
  31  * Redistribution and use in source and binary forms, with or without
  32  * modification, are permitted provided that the following conditions
  33  * are met:
  34  * 1. Redistributions of source code must retain the above copyright
  35  *    notice, this list of conditions and the following disclaimer.
  36  * 2. Redistributions in binary form must reproduce the above copyright
  37  *    notice, this list of conditions and the following disclaimer in the
  38  *    documentation and/or other materials provided with the distribution.
  39  * 3. All advertising materials mentioning features or use of this software
  40  *    must display the following acknowledgement:
  41  *      This product includes software developed by the University of
  42  *      California, Berkeley and its contributors.
  43  * 4. Neither the name of the University nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  *
  59  *      @(#)fs.h        8.10 (Berkeley) 10/27/94
  60  *  Modified for ext2fs by Manuel Bouyer.
  61  */
  62 /*
  63  *  ext2fs.h - Headers for Ext2 disk structures.
  64  *
  65  *  Copyright (c) 2000 Apple Computer, Inc.
  66  *
  67  *  DRI: Josh de Cesare
  68  */
  69
  70 /*
  71  * Each disk drive contains some number of file systems.
  72  * A file system consists of a number of cylinder groups.
  73  * Each cylinder group has inodes and data.
  74  *
  75  * A file system is described by its super-block, which in turn
  76  * describes the cylinder groups.  The super-block is critical
  77  * data and is replicated in each cylinder group to protect against
  78  * catastrophic loss.  This is done at `newfs' time and the critical
  79  * super-block data does not change, so the copies need not be
  80  * referenced further unless disaster strikes.
  81  *
  82  * The first boot and super blocks are given in absolute disk addresses.
  83  * The byte-offset forms are preferred, as they don't imply a sector size.
  84  */
  85 #define BBSIZE          1024
  86 #define SBSIZE          1024
  87 #define BBOFF           ((off_t)(0))
  88 #define SBOFF           ((off_t)(BBOFF + BBSIZE))
  89 #define BBLOCK          ((ufs_daddr_t)(0))
  90 #define SBLOCK          ((ufs_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
  91
  92 /*
  93  * Addresses stored in inodes are capable of addressing blocks
  94  * XXX
  95  */
  96
  97 /*
  98  * MINBSIZE is the smallest allowable block size.
  99  * MINBSIZE must be big enough to hold a cylinder group block,
 100  * thus changes to (struct cg) must keep its size within MINBSIZE.
 101  * Note that super blocks are always of size SBSIZE,
 102  * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
 103  */
 104 #define LOG_MINBSIZE 10
 105 #define MINBSIZE        (1 << LOG_MINBSIZE)
 106
 107 /*
 108  * The path name on which the file system is mounted is maintained
 109  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
 110  * the super block for this name.
 111  */
 112 #define MAXMNTLEN       512
 113
 114 /*
 115  * MINFREE gives the minimum acceptable percentage of file system
 116  * blocks which may be free. If the freelist drops below this level
 117  * only the superuser may continue to allocate blocks. This may
 118  * be set to 0 if no reserve of free blocks is deemed necessary,
 119  * however throughput drops by fifty percent if the file system
 120  * is run at between 95% and 100% full; thus the minimum default
 121  * value of fs_minfree is 5%. However, to get good clustering
 122  * performance, 10% is a better choice. hence we use 10% as our
 123  * default value. With 10% free space, fragmentation is not a
 124  * problem, so we choose to optimize for time.
 125  */
 126 #define MINFREE         5
 127
 128 /*
 129  * Super block for an ext2fs file system.
 130  */
 131 struct ext2fs {
 132         u_int32_t  e2fs_icount;         /* Inode count */
 133         u_int32_t  e2fs_bcount;         /* blocks count */
 134         u_int32_t  e2fs_rbcount;        /* reserved blocks count */
 135         u_int32_t  e2fs_fbcount;        /* free blocks count */
 136         u_int32_t  e2fs_ficount;        /* free inodes count */
 137         u_int32_t  e2fs_first_dblock;   /* first data block */
 138         u_int32_t  e2fs_log_bsize;      /* block size = 1024*(2^e2fs_log_bsize) */
 139         u_int32_t  e2fs_fsize;          /* fragment size */
 140         u_int32_t  e2fs_bpg;            /* blocks per group */
 141         u_int32_t  e2fs_fpg;            /* frags per group */
 142         u_int32_t  e2fs_ipg;            /* inodes per group */
 143         u_int32_t  e2fs_mtime;          /* mount time */
 144         u_int32_t  e2fs_wtime;          /* write time */
 145         u_int16_t  e2fs_mnt_count;      /* mount count */
 146         u_int16_t  e2fs_max_mnt_count;  /* max mount count */
 147         u_int16_t  e2fs_magic;          /* magic number */
 148         u_int16_t  e2fs_state;          /* file system state */
 149         u_int16_t  e2fs_beh;            /* behavior on errors */
 150         u_int16_t  e2fs_minrev;         /* minor revision level */
 151         u_int32_t  e2fs_lastfsck;       /* time of last fsck */
 152         u_int32_t  e2fs_fsckintv;       /* max time between fscks */
 153         u_int32_t  e2fs_creator;        /* creator OS */
 154         u_int32_t  e2fs_rev;            /* revision level */
 155         u_int16_t  e2fs_ruid;           /* default uid for reserved blocks */
 156         u_int16_t  e2fs_rgid;           /* default gid for reserved blocks */
 157         /* EXT2_DYNAMIC_REV superblocks */
 158         u_int32_t  e2fs_first_ino;      /* first non-reserved inode */
 159         u_int16_t  e2fs_inode_size;     /* size of inode structure */
 160         u_int16_t  e2fs_block_group_nr; /* block grp number of this sblk*/
 161         u_int32_t  e2fs_features_compat; /*  compatible feature set */
 162         u_int32_t  e2fs_features_incompat; /* incompatible feature set */
 163         u_int32_t  e2fs_features_rocompat; /* RO-compatible feature set */
 164         u_int8_t   e2fs_uuid[16];       /* 128-bit uuid for volume */
 165         char       e2fs_vname[16];      /* volume name */
 166         char       e2fs_fsmnt[64];      /* name mounted on */
 167         u_int32_t  e2fs_algo;           /* For compression */
 168         u_int8_t   e2fs_prealloc;       /* # of blocks to preallocate */
 169         u_int8_t   e2fs_dir_prealloc;   /* # of blocks to preallocate for dir */
 170         u_int16_t  pad1;
 171         u_int32_t  reserved2[204];
 172 };
 173
 174
 175 /* in-memory data for ext2fs */
 176 struct m_ext2fs {
 177         struct ext2fs e2fs;
 178         u_char  e2fs_fsmnt[MAXMNTLEN];  /* name mounted on */
 179         int8_t  e2fs_ronly;     /* mounted read-only flag */
 180         int8_t  e2fs_fmod;      /* super block modified flag */
 181         int32_t e2fs_bsize;     /* block size */
 182         int32_t e2fs_bshift;    /* ``lblkno'' calc of logical blkno */
 183         int32_t e2fs_bmask;     /* ``blkoff'' calc of blk offsets */
 184         int64_t e2fs_qbmask;    /* ~fs_bmask - for use with quad size */
 185         int32_t e2fs_fsbtodb;   /* fsbtodb and dbtofsb shift constant */
 186         int32_t e2fs_ncg;       /* number of cylinder groups */
 187         int32_t e2fs_ngdb;      /* number of group descriptor block */
 188         int32_t e2fs_ipb;       /* number of inodes per block */
 189         int32_t e2fs_itpg;      /* number of inode table per group */
 190         struct  ext2_gd *e2fs_gd; /* group descripors */
 191 };
 192
 193
 194
 195 /*
 196  * Filesystem identification
 197  */
 198 #define E2FS_MAGIC      0xef53  /* the ext2fs magic number */
 199 #define E2FS_REV0       0       /* revision levels */
 200 #define E2FS_REV1       1       /* revision levels */
 201
 202 /* compatible/imcompatible features */
 203 #define EXT2F_COMPAT_PREALLOC           0x0001
 204
 205 #define EXT2F_ROCOMPAT_SPARSESUPER      0x0001
 206 #define EXT2F_ROCOMPAT_LARGEFILE        0x0002
 207 #define EXT2F_ROCOMPAT_BTREE_DIR        0x0004
 208
 209 #define EXT2F_INCOMPAT_COMP             0x0001
 210 #define EXT2F_INCOMPAT_FTYPE            0x0002
 211
 212 /* features supported in this implementation */
 213 #define EXT2F_COMPAT_SUPP               0x0000
 214 #define EXT2F_ROCOMPAT_SUPP             EXT2F_ROCOMPAT_SPARSESUPER
 215 #define EXT2F_INCOMPAT_SUPP             EXT2F_INCOMPAT_FTYPE
 216
 217 /*
 218  * OS identification
 219  */
 220 #define E2FS_OS_LINUX 0
 221 #define E2FS_OS_HURD  1
 222 #define E2FS_OS_MASIX 2
 223
 224 /*
 225  * Filesystem clean flags
 226  */
 227 #define E2FS_ISCLEAN    0x01
 228 #define E2FS_ERRORS     0x02
 229
 230 /* ext2 file system block group descriptor */
 231
 232 struct ext2_gd {
 233         u_int32_t ext2bgd_b_bitmap;     /* blocks bitmap block */
 234         u_int32_t ext2bgd_i_bitmap;     /* inodes bitmap block */
 235         u_int32_t ext2bgd_i_tables;     /* inodes table block  */
 236         u_int16_t ext2bgd_nbfree;       /* number of free blocks */
 237         u_int16_t ext2bgd_nifree;       /* number of free inodes */
 238         u_int16_t ext2bgd_ndirs;        /* number of directories */
 239         u_int16_t reserved;
 240         u_int32_t reserved2[3];
 241
 242 };
 243
 244
 245 /*
 246  * If the EXT2F_ROCOMPAT_SPARSESUPER flag is set, the cylinder group has a
 247  * copy of the super and cylinder group descriptors blocks only if it's
 248  * a power of 3, 5 or 7
 249  */
 250
 251 static __inline__ int cg_has_sb __P((int)) __attribute__((__unused__));
 252 static __inline int
 253 cg_has_sb(i)
 254         int i;
 255 {
 256         int a3 ,a5 , a7;
 257
 258         if (i == 0 || i == 1)
 259                 return 1;
 260         for (a3 = 3, a5 = 5, a7 = 7;
 261             a3 <= i || a5 <= i || a7 <= i;
 262             a3 *= 3, a5 *= 5, a7 *= 7)
 263                 if (i == a3 || i == a5 || i == a7)
 264                         return 1;
 265         return 0;
 266 }
 267
 268 /* EXT2FS metadatas are stored in little-endian byte order. These macros
 269  * helps reading theses metadatas
 270  */
 271
 272 #if BYTE_ORDER == LITTLE_ENDIAN
 273 #       define h2fs16(x) (x)
 274 #       define h2fs32(x) (x)
 275 #       define fs2h16(x) (x)
 276 #       define fs2h32(x) (x)
 277 #       define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE);
 278 #       define e2fs_cgload(old, new, size) memcpy((new), (old), (size));
 279 #       define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE);
 280 #       define e2fs_cgsave(old, new, size) memcpy((new), (old), (size));
 281 #else
 282 void e2fs_sb_bswap __P((struct ext2fs *, struct ext2fs *));
 283 void e2fs_cg_bswap __P((struct ext2_gd *, struct ext2_gd *, int));
 284 #       define h2fs16(x) bswap16(x)
 285 #       define h2fs32(x) bswap32(x)
 286 #       define fs2h16(x) bswap16(x)
 287 #       define fs2h32(x) bswap32(x)
 288 #       define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new))
 289 #       define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size));
 290 #       define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new))
 291 #       define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size));
 292 #endif
 293
 294 /*
 295  * Turn file system block numbers into disk block addresses.
 296  * This maps file system blocks to device size blocks.
 297  */
 298 #define fsbtodb(fs, b)  ((b) << (fs)->e2fs_fsbtodb)
 299 #define dbtofsb(fs, b)  ((b) >> (fs)->e2fs_fsbtodb)
 300
 301 /*
 302  * Macros for handling inode numbers:
 303  *       inode number to file system block offset.
 304  *       inode number to cylinder group number.
 305  *       inode number to file system block address.
 306  */
 307 #define ino_to_cg(fs, x)        (((x) - 1) / (fs)->e2fs.e2fs_ipg)
 308 #define ino_to_fsba(fs, x)                                              \
 309         ((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \
 310         (((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb)
 311 #define ino_to_fsbo(fs, x)      (((x)-1) % (fs)->e2fs_ipb)
 312
 313 /*
 314  * Give cylinder group number for a file system block.
 315  * Give cylinder group block number for a file system block.
 316  */
 317 #define dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg)
 318 #define dtogd(fs, d) \
 319         (((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg)
 320
 321 /*
 322  * The following macros optimize certain frequently calculated
 323  * quantities by using shifts and masks in place of divisions
 324  * modulos and multiplications.
 325  */
 326 #define blkoff(fs, loc)         /* calculates (loc % fs->e2fs_bsize) */ \
 327         ((loc) & (fs)->e2fs_qbmask)
 328 #define lblktosize(fs, blk)     /* calculates (blk * fs->e2fs_bsize) */ \
 329         ((blk) << (fs)->e2fs_bshift)
 330 #define lblkno(fs, loc)         /* calculates (loc / fs->e2fs_bsize) */ \
 331         ((loc) >> (fs)->e2fs_bshift)
 332 #define blkroundup(fs, size)    /* calculates roundup(size, fs->e2fs_bsize) */ \
 333         (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
 334 #define fragroundup(fs, size)   /* calculates roundup(size, fs->e2fs_bsize) */ \
 335         (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
 336 /*
 337  * Determine the number of available frags given a
 338  * percentage to hold in reserve.
 339  */
 340 #define freespace(fs) \
 341    ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount)
 342
 343 /*
 344  * Number of indirects in a file system block.
 345  */
 346 #define NINDIR(fs)      ((fs)->e2fs_bsize / sizeof(u_int32_t))