1 /* $OpenBSD: ext2fs.h,v 1.14 2010/02/16 08:24:13 otto Exp $ */ 2 /* $NetBSD: ext2fs.h,v 1.10 2000/01/28 16:00:23 bouyer Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Manuel Bouyer. 6 * Copyright (c) 1982, 1986, 1993 7 * The Regents of the University of California. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)fs.h 8.10 (Berkeley) 10/27/94 34 * Modified for ext2fs by Manuel Bouyer. 35 */ 36 37 #include <machine/endian.h> 38 39 /* 40 * Each disk drive contains some number of file systems. 41 * A file system consists of a number of cylinder groups. 42 * Each cylinder group has inodes and data. 43 * 44 * A file system is described by its super-block, which in turn 45 * describes the cylinder groups. The super-block is critical 46 * data and is replicated in each cylinder group to protect against 47 * catastrophic loss. This is done at `newfs' time and the critical 48 * super-block data does not change, so the copies need not be 49 * referenced further unless disaster strikes. 50 * 51 * The first boot and super blocks are given in absolute disk addresses. 52 * The byte-offset forms are preferred, as they don't imply a sector size. 53 */ 54 #define BBSIZE 1024 55 #define SBSIZE 1024 56 #define BBOFF ((off_t)(0)) 57 #define SBOFF ((off_t)(BBOFF + BBSIZE)) 58 #define BBLOCK ((daddr64_t)(0)) 59 #define SBLOCK ((daddr64_t)(BBLOCK + BBSIZE / DEV_BSIZE)) 60 61 /* 62 * Addresses stored in inodes are capable of addressing blocks 63 * XXX 64 */ 65 66 /* 67 * MINBSIZE is the smallest allowable block size. 68 * MINBSIZE must be big enough to hold a cylinder group block, 69 * thus changes to (struct cg) must keep its size within MINBSIZE. 70 * Note that super blocks are always of size SBSIZE, 71 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. 72 */ 73 #define LOG_MINBSIZE 10 74 #define MINBSIZE (1 << LOG_MINBSIZE) 75 76 /* 77 * The path name on which the file system is mounted is maintained 78 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 79 * the super block for this name. 80 */ 81 #define MAXMNTLEN 512 82 83 /* 84 * MINFREE gives the minimum acceptable percentage of file system 85 * blocks which may be free. If the freelist drops below this level 86 * only the superuser may continue to allocate blocks. This may 87 * be set to 0 if no reserve of free blocks is deemed necessary, 88 * however throughput drops by fifty percent if the file system 89 * is run at between 95% and 100% full; thus the minimum default 90 * value of fs_minfree is 5%. However, to get good clustering 91 * performance, 10% is a better choice. hence we use 10% as our 92 * default value. With 10% free space, fragmentation is not a 93 * problem, so we choose to optimize for time. 94 */ 95 #define MINFREE 5 96 97 /* 98 * Super block for an ext2fs file system. 99 */ 100 struct ext2fs { 101 u_int32_t e2fs_icount; /* Inode count */ 102 u_int32_t e2fs_bcount; /* blocks count */ 103 u_int32_t e2fs_rbcount; /* reserved blocks count */ 104 u_int32_t e2fs_fbcount; /* free blocks count */ 105 u_int32_t e2fs_ficount; /* free inodes count */ 106 u_int32_t e2fs_first_dblock; /* first data block */ 107 u_int32_t e2fs_log_bsize; /* block size = 1024*(2^e2fs_log_bsize) */ 108 u_int32_t e2fs_fsize; /* fragment size */ 109 u_int32_t e2fs_bpg; /* blocks per group */ 110 u_int32_t e2fs_fpg; /* frags per group */ 111 u_int32_t e2fs_ipg; /* inodes per group */ 112 u_int32_t e2fs_mtime; /* mount time */ 113 u_int32_t e2fs_wtime; /* write time */ 114 u_int16_t e2fs_mnt_count; /* mount count */ 115 u_int16_t e2fs_max_mnt_count; /* max mount count */ 116 u_int16_t e2fs_magic; /* magic number */ 117 u_int16_t e2fs_state; /* file system state */ 118 u_int16_t e2fs_beh; /* behavior on errors */ 119 u_int16_t e2fs_minrev; /* minor revision level */ 120 u_int32_t e2fs_lastfsck; /* time of last fsck */ 121 u_int32_t e2fs_fsckintv; /* max time between fscks */ 122 u_int32_t e2fs_creator; /* creator OS */ 123 u_int32_t e2fs_rev; /* revision level */ 124 u_int16_t e2fs_ruid; /* default uid for reserved blocks */ 125 u_int16_t e2fs_rgid; /* default gid for reserved blocks */ 126 /* EXT2_DYNAMIC_REV superblocks */ 127 u_int32_t e2fs_first_ino; /* first non-reserved inode */ 128 u_int16_t e2fs_inode_size; /* size of inode structure */ 129 u_int16_t e2fs_block_group_nr; /* block grp number of this sblk*/ 130 u_int32_t e2fs_features_compat; /* compatible feature set */ 131 u_int32_t e2fs_features_incompat; /* incompatible feature set */ 132 u_int32_t e2fs_features_rocompat; /* RO-compatible feature set */ 133 u_int8_t e2fs_uuid[16]; /* 128-bit uuid for volume */ 134 char e2fs_vname[16]; /* volume name */ 135 char e2fs_fsmnt[64]; /* name mounted on */ 136 u_int32_t e2fs_algo; /* For compression */ 137 u_int8_t e2fs_prealloc; /* # of blocks to preallocate */ 138 u_int8_t e2fs_dir_prealloc; /* # of blocks to preallocate for dir */ 139 u_int16_t e2fs_reserved_ngdb; /* # of reserved gd blocks for resize */ 140 u_int32_t reserved2[204]; 141 }; 142 143 144 /* in-memory data for ext2fs */ 145 struct m_ext2fs { 146 struct ext2fs e2fs; 147 u_char e2fs_fsmnt[MAXMNTLEN]; /* name mounted on */ 148 int8_t e2fs_ronly; /* mounted read-only flag */ 149 int8_t e2fs_fmod; /* super block modified flag */ 150 int32_t e2fs_bsize; /* block size */ 151 int32_t e2fs_bshift; /* ``lblkno'' calc of logical blkno */ 152 int32_t e2fs_bmask; /* ``blkoff'' calc of blk offsets */ 153 int64_t e2fs_qbmask; /* ~fs_bmask - for use with quad size */ 154 int32_t e2fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ 155 int32_t e2fs_ncg; /* number of cylinder groups */ 156 int32_t e2fs_ngdb; /* number of group descriptor block */ 157 int32_t e2fs_ipb; /* number of inodes per block */ 158 int32_t e2fs_itpg; /* number of inode table per group */ 159 struct ext2_gd *e2fs_gd; /* group descriptors */ 160 }; 161 162 163 164 /* 165 * Filesystem identification 166 */ 167 #define E2FS_MAGIC 0xef53 /* the ext2fs magic number */ 168 #define E2FS_REV0 0 /* revision levels */ 169 #define E2FS_REV1 1 /* revision levels */ 170 171 /* compatible/imcompatible features */ 172 #define EXT2F_COMPAT_PREALLOC 0x0001 173 #define EXT2F_COMPAT_HASJOURNAL 0x0004 174 #define EXT2F_COMPAT_RESIZE 0x0010 175 176 177 #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 #define EXT2F_INCOMPAT_RECOVER 0x0004 184 #define EXT2F_INCOMPAT_JOURNAL_DEV 0x0008 185 186 /* features supported in this implementation */ 187 #define EXT2F_COMPAT_SUPP 0x0000 188 #define EXT2F_ROCOMPAT_SUPP (EXT2F_ROCOMPAT_SPARSESUPER \ 189 | EXT2F_ROCOMPAT_LARGEFILE) 190 #define EXT2F_INCOMPAT_SUPP EXT2F_INCOMPAT_FTYPE 191 192 /* 193 * Definitions of behavior on errors 194 */ 195 #define E2FS_BEH_CONTINUE 1 /* continue operation */ 196 #define E2FS_BEH_READONLY 2 /* remount fs read only */ 197 #define E2FS_BEH_PANIC 3 /* cause panic */ 198 #define E2FS_BEH_DEFAULT E2FS_BEH_CONTINUE 199 200 /* 201 * OS identification 202 */ 203 #define E2FS_OS_LINUX 0 204 #define E2FS_OS_HURD 1 205 #define E2FS_OS_MASIX 2 206 207 /* 208 * Filesystem clean flags 209 */ 210 #define E2FS_ISCLEAN 0x01 211 #define E2FS_ERRORS 0x02 212 213 /* ext2 file system block group descriptor */ 214 215 struct ext2_gd { 216 u_int32_t ext2bgd_b_bitmap; /* blocks bitmap block */ 217 u_int32_t ext2bgd_i_bitmap; /* inodes bitmap block */ 218 u_int32_t ext2bgd_i_tables; /* inodes table block */ 219 u_int16_t ext2bgd_nbfree; /* number of free blocks */ 220 u_int16_t ext2bgd_nifree; /* number of free inodes */ 221 u_int16_t ext2bgd_ndirs; /* number of directories */ 222 u_int16_t reserved; 223 u_int32_t reserved2[3]; 224 }; 225 226 /* 227 * If the EXT2F_ROCOMPAT_SPARSESUPER flag is set, the cylinder group has a 228 * copy of the super and cylinder group descriptors blocks only if it's 229 * a power of 3, 5 or 7 230 */ 231 232 static __inline__ int cg_has_sb(int) __attribute__((__unused__)); 233 static __inline int 234 cg_has_sb(i) 235 int i; 236 { 237 int a3 ,a5 , a7; 238 239 if (i == 0 || i == 1) 240 return 1; 241 for (a3 = 3, a5 = 5, a7 = 7; 242 a3 <= i || a5 <= i || a7 <= i; 243 a3 *= 3, a5 *= 5, a7 *= 7) 244 if (i == a3 || i == a5 || i == a7) 245 return 1; 246 return 0; 247 } 248 249 /* 250 * EXT2FS metadatas are stored in little-endian byte order. These macros 251 * helps reading theses metadatas 252 */ 253 254 #define h2fs16(x) htole16(x) 255 #define h2fs32(x) htole32(x) 256 #define fs2h16(x) letoh16(x) 257 #define fs2h32(x) letoh32(x) 258 #if BYTE_ORDER == LITTLE_ENDIAN 259 #define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE); 260 #define e2fs_cgload(old, new, size) memcpy((new), (old), (size)); 261 #define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE); 262 #define e2fs_cgsave(old, new, size) memcpy((new), (old), (size)); 263 #else 264 void e2fs_sb_bswap(struct ext2fs *, struct ext2fs *); 265 void e2fs_cg_bswap(struct ext2_gd *, struct ext2_gd *, int); 266 #define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new)) 267 #define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size)); 268 #define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new)) 269 #define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size)); 270 #endif 271 272 /* 273 * Turn file system block numbers into disk block addresses. 274 * This maps file system blocks to device size blocks. 275 */ 276 #define fsbtodb(fs, b) ((b) << (fs)->e2fs_fsbtodb) 277 #define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb) 278 279 /* 280 * Macros for handling inode numbers: 281 * inode number to file system block offset. 282 * inode number to cylinder group number. 283 * inode number to file system block address. 284 */ 285 #define ino_to_cg(fs, x) (((x) - 1) / (fs)->e2fs.e2fs_ipg) 286 #define ino_to_fsba(fs, x) \ 287 ((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \ 288 (((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb) 289 #define ino_to_fsbo(fs, x) (((x)-1) % (fs)->e2fs_ipb) 290 291 /* 292 * Give cylinder group number for a file system block. 293 * Give cylinder group block number for a file system block. 294 */ 295 #define dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg) 296 #define dtogd(fs, d) \ 297 (((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg) 298 299 /* 300 * The following macros optimize certain frequently calculated 301 * quantities by using shifts and masks in place of divisions 302 * modulos and multiplications. 303 */ 304 #define blkoff(fs, loc) /* calculates (loc % fs->e2fs_bsize) */ \ 305 ((loc) & (fs)->e2fs_qbmask) 306 #define lblktosize(fs, blk) /* calculates (blk * fs->e2fs_bsize) */ \ 307 ((blk) << (fs)->e2fs_bshift) 308 #define lblkno(fs, loc) /* calculates (loc / fs->e2fs_bsize) */ \ 309 ((loc) >> (fs)->e2fs_bshift) 310 #define blkroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \ 311 (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask) 312 #define fragroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \ 313 (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask) 314 /* 315 * Determine the number of available frags given a 316 * percentage to hold in reserve. 317 */ 318 #define freespace(fs) \ 319 ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount) 320 321 /* 322 * Number of indirects in a file system block. 323 */ 324 #define NINDIR(fs) ((fs)->e2fs_bsize / sizeof(u_int32_t)) 325