/* $NetBSD: ext2fs.h,v 1.2 1997/10/09 15:42:45 bouyer Exp $ */ /* * Copyright (c) 1997 Manuel Bouyer. * Copyright (c) 1982, 1986, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)fs.h 8.10 (Berkeley) 10/27/94 * Modified for ext2fs by Manuel Bouyer. */ /* * Each disk drive contains some number of file systems. * A file system consists of a number of cylinder groups. * Each cylinder group has inodes and data. * * A file system is described by its super-block, which in turn * describes the cylinder groups. The super-block is critical * data and is replicated in each cylinder group to protect against * catastrophic loss. This is done at `newfs' time and the critical * super-block data does not change, so the copies need not be * referenced further unless disaster strikes. * * The first boot and super blocks are given in absolute disk addresses. * The byte-offset forms are preferred, as they don't imply a sector size. */ #define BBSIZE 1024 #define SBSIZE 1024 #define BBOFF ((off_t)(0)) #define SBOFF ((off_t)(BBOFF + BBSIZE)) #define BBLOCK ((daddr_t)(0)) #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE)) /* * Addresses stored in inodes are capable of addressing blocks * XXX */ /* * MINBSIZE is the smallest allowable block size. * MINBSIZE must be big enough to hold a cylinder group block, * thus changes to (struct cg) must keep its size within MINBSIZE. * Note that super blocks are always of size SBSIZE, * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. */ #define LOG_MINBSIZE 10 #define MINBSIZE (1 << LOG_MINBSIZE) /* * The path name on which the file system is mounted is maintained * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in * the super block for this name. */ #define MAXMNTLEN 512 /* * MINFREE gives the minimum acceptable percentage of file system * blocks which may be free. If the freelist drops below this level * only the superuser may continue to allocate blocks. This may * be set to 0 if no reserve of free blocks is deemed necessary, * however throughput drops by fifty percent if the file system * is run at between 95% and 100% full; thus the minimum default * value of fs_minfree is 5%. However, to get good clustering * performance, 10% is a better choice. hence we use 10% as our * default value. With 10% free space, fragmentation is not a * problem, so we choose to optimize for time. */ #define MINFREE 5 /* * Super block for an ext2fs file system. */ struct ext2fs { u_int32_t e2fs_icount; /* Inode count */ u_int32_t e2fs_bcount; /* blocks count */ u_int32_t e2fs_rbcount; /* reserved blocks count */ u_int32_t e2fs_fbcount; /* free blocks count */ u_int32_t e2fs_ficount; /* free inodes count */ u_int32_t e2fs_first_dblock; /* first data block */ u_int32_t e2fs_log_bsize; /* block size = 1024*(2^e2fs_log_bsize) */ u_int32_t e2fs_fsize; /* fragment size */ u_int32_t e2fs_bpg; /* blocks per group */ u_int32_t e2fs_fpg; /* frags per group */ u_int32_t e2fs_ipg; /* inodes per group */ u_int32_t e2fs_mtime; /* mount time */ u_int32_t e2fs_wtime; /* write time */ u_int16_t e2fs_mnt_count; /* mount count */ u_int16_t e2fs_max_mnt_count; /* max mount count */ u_int16_t e2fs_magic; /* magic number */ u_int16_t e2fs_state; /* file system state */ u_int16_t e2fs_beh; /* behavior on errors */ u_int16_t reserved; u_int32_t e2fs_lastfsck; /* time of last fsck */ u_int32_t e2fs_fsckintv; /* max time between fscks */ u_int32_t e2fs_creator; /* creator OS */ u_int32_t e2fs_rev; /* revision level */ u_int16_t e2fs_ruid; /* default uid for reserved blocks */ u_int16_t e2fs_rgid; /* default gid for reserved blocks */ u_int32_t reserved2[235]; }; /* in-memory data for ext2fs */ struct m_ext2fs { struct ext2fs e2fs; u_char e2fs_fsmnt[MAXMNTLEN]; /* name mounted on */ int8_t e2fs_ronly; /* mounted read-only flag */ int8_t e2fs_fmod; /* super block modified flag */ int32_t e2fs_bsize; /* block size */ int32_t e2fs_bshift; /* ``lblkno'' calc of logical blkno */ int32_t e2fs_bmask; /* ``blkoff'' calc of blk offsets */ int64_t e2fs_qbmask; /* ~fs_bmask - for use with quad size */ int32_t e2fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ int32_t e2fs_ncg; /* number of cylinder groups */ int32_t e2fs_ngdb; /* number of group descriptor block */ int32_t e2fs_ipb; /* number of inodes per block */ int32_t e2fs_itpg; /* number of inode table per group */ struct ext2_gd *e2fs_gd; /* group descripors */ }; /* * Filesystem identification */ #define E2FS_MAGIC 0xef53 /* the ext2fs magic number */ #define E2FS_REV 0 /* revision level */ /* * OS identification */ #define E2FS_OS_LINUX 0 #define E2FS_OS_HURD 1 #define E2FS_OS_MASIX 2 /* * Filesystem clean flags */ #define E2FS_ISCLEAN 0x01 #define E2FS_ERRORS 0x02 /* ext2 file system block group descriptor */ struct ext2_gd { u_int32_t ext2bgd_b_bitmap; /* blocks bitmap block */ u_int32_t ext2bgd_i_bitmap; /* inodes bitmap block */ u_int32_t ext2bgd_i_tables; /* inodes table block */ u_int16_t ext2bgd_nbfree; /* number of free blocks */ u_int16_t ext2bgd_nifree; /* number of free inodes */ u_int16_t ext2bgd_ndirs; /* number of directories */ u_int16_t reserved; u_int32_t reserved2[3]; }; /* EXT2FS metadatas are stored in little-endian byte order. These macros * helps reading theses metadatas */ #if BYTE_ORDER == LITTLE_ENDIAN # define h2fs16(x) (x) # define h2fs32(x) (x) # define fs2h16(x) (x) # define fs2h32(x) (x) # define e2fs_sbload(old, new) bcopy((old), (new), SBSIZE); # define e2fs_cgload(old, new, size) bcopy((old), (new), (size)); # define e2fs_sbsave(old, new) bcopy((old), (new), SBSIZE); # define e2fs_cgsave(old, new, size) bcopy((old), (new), (size)); #else void e2fs_sb_bswap __P((struct ext2fs *, struct ext2fs *)); void e2fs_cg_bswap __P((struct ext2_gd *, struct ext2_gd *, int)); # define h2fs16(x) bswap16(x) # define h2fs32(x) bswap32(x) # define fs2h16(x) bswap16(x) # define fs2h32(x) bswap32(x) # define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new)) # define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size)); # define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new)) # define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size)); #endif /* * Turn file system block numbers into disk block addresses. * This maps file system blocks to device size blocks. */ #define fsbtodb(fs, b) ((b) << (fs)->e2fs_fsbtodb) #define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb) /* * Macros for handling inode numbers: * inode number to file system block offset. * inode number to cylinder group number. * inode number to file system block address. */ #define ino_to_cg(fs, x) (((x) - 1) / (fs)->e2fs.e2fs_ipg) #define ino_to_fsba(fs, x) \ ((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \ (((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb) #define ino_to_fsbo(fs, x) (((x)-1) % (fs)->e2fs_ipb) /* * Give cylinder group number for a file system block. * Give cylinder group block number for a file system block. */ #define dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg) #define dtogd(fs, d) \ (((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg) /* * The following macros optimize certain frequently calculated * quantities by using shifts and masks in place of divisions * modulos and multiplications. */ #define blkoff(fs, loc) /* calculates (loc % fs->e2fs_bsize) */ \ ((loc) & (fs)->e2fs_qbmask) #define lblktosize(fs, blk) /* calculates (blk * fs->e2fs_bsize) */ \ ((blk) << (fs)->e2fs_bshift) #define lblkno(fs, loc) /* calculates (loc / fs->e2fs_bsize) */ \ ((loc) >> (fs)->e2fs_bshift) #define blkroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \ (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask) #define fragroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \ (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask) /* * Determine the number of available frags given a * percentage to hold in reserve. */ #define freespace(fs) \ ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount) /* * Number of indirects in a file system block. */ #define NINDIR(fs) ((fs)->e2fs_bsize / sizeof(u_int32_t))