1 /* $NetBSD: ext2fs.h,v 1.10 2000/01/28 16:00:23 bouyer Exp $ */ 2 3 /* 4 * Copyright (c) 1997 Manuel Bouyer. 5 * Copyright (c) 1982, 1986, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)fs.h 8.10 (Berkeley) 10/27/94 37 * Modified for ext2fs by Manuel Bouyer. 38 */ 39 40 #include <machine/bswap.h> 41 42 /* 43 * Each disk drive contains some number of file systems. 44 * A file system consists of a number of cylinder groups. 45 * Each cylinder group has inodes and data. 46 * 47 * A file system is described by its super-block, which in turn 48 * describes the cylinder groups. The super-block is critical 49 * data and is replicated in each cylinder group to protect against 50 * catastrophic loss. This is done at `newfs' time and the critical 51 * super-block data does not change, so the copies need not be 52 * referenced further unless disaster strikes. 53 * 54 * The first boot and super blocks are given in absolute disk addresses. 55 * The byte-offset forms are preferred, as they don't imply a sector size. 56 */ 57 #define BBSIZE 1024 58 #define SBSIZE 1024 59 #define BBOFF ((off_t)(0)) 60 #define SBOFF ((off_t)(BBOFF + BBSIZE)) 61 #define BBLOCK ((ufs_daddr_t)(0)) 62 #define SBLOCK ((ufs_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE)) 63 64 /* 65 * Addresses stored in inodes are capable of addressing blocks 66 * XXX 67 */ 68 69 /* 70 * MINBSIZE is the smallest allowable block size. 71 * MINBSIZE must be big enough to hold a cylinder group block, 72 * thus changes to (struct cg) must keep its size within MINBSIZE. 73 * Note that super blocks are always of size SBSIZE, 74 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. 75 */ 76 #define LOG_MINBSIZE 10 77 #define MINBSIZE (1 << LOG_MINBSIZE) 78 79 /* 80 * The path name on which the file system is mounted is maintained 81 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 82 * the super block for this name. 83 */ 84 #define MAXMNTLEN 512 85 86 /* 87 * MINFREE gives the minimum acceptable percentage of file system 88 * blocks which may be free. If the freelist drops below this level 89 * only the superuser may continue to allocate blocks. This may 90 * be set to 0 if no reserve of free blocks is deemed necessary, 91 * however throughput drops by fifty percent if the file system 92 * is run at between 95% and 100% full; thus the minimum default 93 * value of fs_minfree is 5%. However, to get good clustering 94 * performance, 10% is a better choice. hence we use 10% as our 95 * default value. With 10% free space, fragmentation is not a 96 * problem, so we choose to optimize for time. 97 */ 98 #define MINFREE 5 99 100 /* 101 * Super block for an ext2fs file system. 102 */ 103 struct ext2fs { 104 u_int32_t e2fs_icount; /* Inode count */ 105 u_int32_t e2fs_bcount; /* blocks count */ 106 u_int32_t e2fs_rbcount; /* reserved blocks count */ 107 u_int32_t e2fs_fbcount; /* free blocks count */ 108 u_int32_t e2fs_ficount; /* free inodes count */ 109 u_int32_t e2fs_first_dblock; /* first data block */ 110 u_int32_t e2fs_log_bsize; /* block size = 1024*(2^e2fs_log_bsize) */ 111 u_int32_t e2fs_fsize; /* fragment size */ 112 u_int32_t e2fs_bpg; /* blocks per group */ 113 u_int32_t e2fs_fpg; /* frags per group */ 114 u_int32_t e2fs_ipg; /* inodes per group */ 115 u_int32_t e2fs_mtime; /* mount time */ 116 u_int32_t e2fs_wtime; /* write time */ 117 u_int16_t e2fs_mnt_count; /* mount count */ 118 u_int16_t e2fs_max_mnt_count; /* max mount count */ 119 u_int16_t e2fs_magic; /* magic number */ 120 u_int16_t e2fs_state; /* file system state */ 121 u_int16_t e2fs_beh; /* behavior on errors */ 122 u_int16_t e2fs_minrev; /* minor revision level */ 123 u_int32_t e2fs_lastfsck; /* time of last fsck */ 124 u_int32_t e2fs_fsckintv; /* max time between fscks */ 125 u_int32_t e2fs_creator; /* creator OS */ 126 u_int32_t e2fs_rev; /* revision level */ 127 u_int16_t e2fs_ruid; /* default uid for reserved blocks */ 128 u_int16_t e2fs_rgid; /* default gid for reserved blocks */ 129 /* EXT2_DYNAMIC_REV superblocks */ 130 u_int32_t e2fs_first_ino; /* first non-reserved inode */ 131 u_int16_t e2fs_inode_size; /* size of inode structure */ 132 u_int16_t e2fs_block_group_nr; /* block grp number of this sblk*/ 133 u_int32_t e2fs_features_compat; /* compatible feature set */ 134 u_int32_t e2fs_features_incompat; /* incompatible feature set */ 135 u_int32_t e2fs_features_rocompat; /* RO-compatible feature set */ 136 u_int8_t e2fs_uuid[16]; /* 128-bit uuid for volume */ 137 char e2fs_vname[16]; /* volume name */ 138 char e2fs_fsmnt[64]; /* name mounted on */ 139 u_int32_t e2fs_algo; /* For compression */ 140 u_int8_t e2fs_prealloc; /* # of blocks to preallocate */ 141 u_int8_t e2fs_dir_prealloc; /* # of blocks to preallocate for dir */ 142 u_int16_t pad1; 143 u_int32_t reserved2[204]; 144 }; 145 146 147 /* in-memory data for ext2fs */ 148 struct m_ext2fs { 149 struct ext2fs e2fs; 150 u_char e2fs_fsmnt[MAXMNTLEN]; /* name mounted on */ 151 int8_t e2fs_ronly; /* mounted read-only flag */ 152 int8_t e2fs_fmod; /* super block modified flag */ 153 int32_t e2fs_bsize; /* block size */ 154 int32_t e2fs_bshift; /* ``lblkno'' calc of logical blkno */ 155 int32_t e2fs_bmask; /* ``blkoff'' calc of blk offsets */ 156 int64_t e2fs_qbmask; /* ~fs_bmask - for use with quad size */ 157 int32_t e2fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ 158 int32_t e2fs_ncg; /* number of cylinder groups */ 159 int32_t e2fs_ngdb; /* number of group descriptor block */ 160 int32_t e2fs_ipb; /* number of inodes per block */ 161 int32_t e2fs_itpg; /* number of inode table per group */ 162 struct ext2_gd *e2fs_gd; /* group descripors */ 163 }; 164 165 166 167 /* 168 * Filesystem identification 169 */ 170 #define E2FS_MAGIC 0xef53 /* the ext2fs magic number */ 171 #define E2FS_REV0 0 /* revision levels */ 172 #define E2FS_REV1 1 /* revision levels */ 173 174 /* compatible/imcompatible features */ 175 #define EXT2F_COMPAT_PREALLOC 0x0001 176 177 #define EXT2F_ROCOMPAT_SPARSESUPER 0x0001 178 #define EXT2F_ROCOMPAT_LARGEFILE 0x0002 179 #define EXT2F_ROCOMPAT_BTREE_DIR 0x0004 180 181 #define EXT2F_INCOMPAT_COMP 0x0001 182 #define EXT2F_INCOMPAT_FTYPE 0x0002 183 184 /* features supported in this implementation */ 185 #define EXT2F_COMPAT_SUPP 0x0000 186 #define EXT2F_ROCOMPAT_SUPP EXT2F_ROCOMPAT_SPARSESUPER 187 #define EXT2F_INCOMPAT_SUPP EXT2F_INCOMPAT_FTYPE 188 189 /* 190 * OS identification 191 */ 192 #define E2FS_OS_LINUX 0 193 #define E2FS_OS_HURD 1 194 #define E2FS_OS_MASIX 2 195 196 /* 197 * Filesystem clean flags 198 */ 199 #define E2FS_ISCLEAN 0x01 200 #define E2FS_ERRORS 0x02 201 202 /* ext2 file system block group descriptor */ 203 204 struct ext2_gd { 205 u_int32_t ext2bgd_b_bitmap; /* blocks bitmap block */ 206 u_int32_t ext2bgd_i_bitmap; /* inodes bitmap block */ 207 u_int32_t ext2bgd_i_tables; /* inodes table block */ 208 u_int16_t ext2bgd_nbfree; /* number of free blocks */ 209 u_int16_t ext2bgd_nifree; /* number of free inodes */ 210 u_int16_t ext2bgd_ndirs; /* number of directories */ 211 u_int16_t reserved; 212 u_int32_t reserved2[3]; 213 214 }; 215 216 217 /* 218 * If the EXT2F_ROCOMPAT_SPARSESUPER flag is set, the cylinder group has a 219 * copy of the super and cylinder group descriptors blocks only if it's 220 * a power of 3, 5 or 7 221 */ 222 223 static __inline__ int cg_has_sb __P((int)) __attribute__((__unused__)); 224 static __inline int 225 cg_has_sb(i) 226 int i; 227 { 228 int a3 ,a5 , a7; 229 230 if (i == 0 || i == 1) 231 return 1; 232 for (a3 = 3, a5 = 5, a7 = 7; 233 a3 <= i || a5 <= i || a7 <= i; 234 a3 *= 3, a5 *= 5, a7 *= 7) 235 if (i == a3 || i == a5 || i == a7) 236 return 1; 237 return 0; 238 } 239 240 /* EXT2FS metadatas are stored in little-endian byte order. These macros 241 * helps reading theses metadatas 242 */ 243 244 #if BYTE_ORDER == LITTLE_ENDIAN 245 # define h2fs16(x) (x) 246 # define h2fs32(x) (x) 247 # define fs2h16(x) (x) 248 # define fs2h32(x) (x) 249 # define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE); 250 # define e2fs_cgload(old, new, size) memcpy((new), (old), (size)); 251 # define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE); 252 # define e2fs_cgsave(old, new, size) memcpy((new), (old), (size)); 253 #else 254 void e2fs_sb_bswap __P((struct ext2fs *, struct ext2fs *)); 255 void e2fs_cg_bswap __P((struct ext2_gd *, struct ext2_gd *, int)); 256 # define h2fs16(x) bswap16(x) 257 # define h2fs32(x) bswap32(x) 258 # define fs2h16(x) bswap16(x) 259 # define fs2h32(x) bswap32(x) 260 # define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new)) 261 # define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size)); 262 # define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new)) 263 # define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size)); 264 #endif 265 266 /* 267 * Turn file system block numbers into disk block addresses. 268 * This maps file system blocks to device size blocks. 269 */ 270 #define fsbtodb(fs, b) ((b) << (fs)->e2fs_fsbtodb) 271 #define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb) 272 273 /* 274 * Macros for handling inode numbers: 275 * inode number to file system block offset. 276 * inode number to cylinder group number. 277 * inode number to file system block address. 278 */ 279 #define ino_to_cg(fs, x) (((x) - 1) / (fs)->e2fs.e2fs_ipg) 280 #define ino_to_fsba(fs, x) \ 281 ((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \ 282 (((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb) 283 #define ino_to_fsbo(fs, x) (((x)-1) % (fs)->e2fs_ipb) 284 285 /* 286 * Give cylinder group number for a file system block. 287 * Give cylinder group block number for a file system block. 288 */ 289 #define dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg) 290 #define dtogd(fs, d) \ 291 (((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg) 292 293 /* 294 * The following macros optimize certain frequently calculated 295 * quantities by using shifts and masks in place of divisions 296 * modulos and multiplications. 297 */ 298 #define blkoff(fs, loc) /* calculates (loc % fs->e2fs_bsize) */ \ 299 ((loc) & (fs)->e2fs_qbmask) 300 #define lblktosize(fs, blk) /* calculates (blk * fs->e2fs_bsize) */ \ 301 ((blk) << (fs)->e2fs_bshift) 302 #define lblkno(fs, loc) /* calculates (loc / fs->e2fs_bsize) */ \ 303 ((loc) >> (fs)->e2fs_bshift) 304 #define blkroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \ 305 (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask) 306 #define fragroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \ 307 (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask) 308 /* 309 * Determine the number of available frags given a 310 * percentage to hold in reserve. 311 */ 312 #define freespace(fs) \ 313 ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount) 314 315 /* 316 * Number of indirects in a file system block. 317 */ 318 #define NINDIR(fs) ((fs)->e2fs_bsize / sizeof(u_int32_t)) 319