Annotation of sys/ufs/ext2fs/ext2fs.h, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: ext2fs.h,v 1.12 2007/06/02 00:45:50 pedro 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 ((daddr_t)(0))
! 59: #define SBLOCK ((daddr_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 pad1;
! 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:
! 174: #define EXT2F_ROCOMPAT_SPARSESUPER 0x0001
! 175: #define EXT2F_ROCOMPAT_LARGEFILE 0x0002
! 176: #define EXT2F_ROCOMPAT_BTREE_DIR 0x0004
! 177:
! 178: #define EXT2F_INCOMPAT_COMP 0x0001
! 179: #define EXT2F_INCOMPAT_FTYPE 0x0002
! 180: #define EXT2F_INCOMPAT_RECOVER 0x0004
! 181: #define EXT2F_INCOMPAT_JOURNAL_DEV 0x0008
! 182:
! 183: /* features supported in this implementation */
! 184: #define EXT2F_COMPAT_SUPP 0x0000
! 185: #define EXT2F_ROCOMPAT_SUPP (EXT2F_ROCOMPAT_SPARSESUPER \
! 186: | EXT2F_ROCOMPAT_LARGEFILE)
! 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: * If the EXT2F_ROCOMPAT_SPARSESUPER flag is set, the cylinder group has a
! 217: * copy of the super and cylinder group descriptors blocks only if it's
! 218: * a power of 3, 5 or 7
! 219: */
! 220:
! 221: static __inline__ int cg_has_sb(int) __attribute__((__unused__));
! 222: static __inline int
! 223: cg_has_sb(i)
! 224: int i;
! 225: {
! 226: int a3 ,a5 , a7;
! 227:
! 228: if (i == 0 || i == 1)
! 229: return 1;
! 230: for (a3 = 3, a5 = 5, a7 = 7;
! 231: a3 <= i || a5 <= i || a7 <= i;
! 232: a3 *= 3, a5 *= 5, a7 *= 7)
! 233: if (i == a3 || i == a5 || i == a7)
! 234: return 1;
! 235: return 0;
! 236: }
! 237:
! 238: /*
! 239: * EXT2FS metadatas are stored in little-endian byte order. These macros
! 240: * helps reading theses metadatas
! 241: */
! 242:
! 243: #define h2fs16(x) htole16(x)
! 244: #define h2fs32(x) htole32(x)
! 245: #define fs2h16(x) letoh16(x)
! 246: #define fs2h32(x) letoh32(x)
! 247: #if BYTE_ORDER == LITTLE_ENDIAN
! 248: #define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE);
! 249: #define e2fs_cgload(old, new, size) memcpy((new), (old), (size));
! 250: #define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE);
! 251: #define e2fs_cgsave(old, new, size) memcpy((new), (old), (size));
! 252: #else
! 253: void e2fs_sb_bswap(struct ext2fs *, struct ext2fs *);
! 254: void e2fs_cg_bswap(struct ext2_gd *, struct ext2_gd *, int);
! 255: #define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new))
! 256: #define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size));
! 257: #define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new))
! 258: #define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size));
! 259: #endif
! 260:
! 261: /*
! 262: * Turn file system block numbers into disk block addresses.
! 263: * This maps file system blocks to device size blocks.
! 264: */
! 265: #define fsbtodb(fs, b) ((b) << (fs)->e2fs_fsbtodb)
! 266: #define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb)
! 267:
! 268: /*
! 269: * Macros for handling inode numbers:
! 270: * inode number to file system block offset.
! 271: * inode number to cylinder group number.
! 272: * inode number to file system block address.
! 273: */
! 274: #define ino_to_cg(fs, x) (((x) - 1) / (fs)->e2fs.e2fs_ipg)
! 275: #define ino_to_fsba(fs, x) \
! 276: ((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \
! 277: (((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb)
! 278: #define ino_to_fsbo(fs, x) (((x)-1) % (fs)->e2fs_ipb)
! 279:
! 280: /*
! 281: * Give cylinder group number for a file system block.
! 282: * Give cylinder group block number for a file system block.
! 283: */
! 284: #define dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg)
! 285: #define dtogd(fs, d) \
! 286: (((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg)
! 287:
! 288: /*
! 289: * The following macros optimize certain frequently calculated
! 290: * quantities by using shifts and masks in place of divisions
! 291: * modulos and multiplications.
! 292: */
! 293: #define blkoff(fs, loc) /* calculates (loc % fs->e2fs_bsize) */ \
! 294: ((loc) & (fs)->e2fs_qbmask)
! 295: #define lblktosize(fs, blk) /* calculates (blk * fs->e2fs_bsize) */ \
! 296: ((blk) << (fs)->e2fs_bshift)
! 297: #define lblkno(fs, loc) /* calculates (loc / fs->e2fs_bsize) */ \
! 298: ((loc) >> (fs)->e2fs_bshift)
! 299: #define blkroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \
! 300: (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
! 301: #define fragroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \
! 302: (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
! 303: /*
! 304: * Determine the number of available frags given a
! 305: * percentage to hold in reserve.
! 306: */
! 307: #define freespace(fs) \
! 308: ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount)
! 309:
! 310: /*
! 311: * Number of indirects in a file system block.
! 312: */
! 313: #define NINDIR(fs) ((fs)->e2fs_bsize / sizeof(u_int32_t))
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