1 /*- 2 * modified for EXT2FS support in Lites 1.1 3 * 4 * Aug 1995, Godmar Back (gback@cs.utah.edu) 5 * University of Utah, Department of Computer Science 6 */ 7 /*- 8 * Copyright (c) 1982, 1986, 1993 9 * The Regents of the University of California. All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)fs.h 8.7 (Berkeley) 4/19/94 36 * $FreeBSD$ 37 */ 38 39 #ifndef _FS_EXT2FS_FS_H_ 40 #define _FS_EXT2FS_FS_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 SBSIZE 1024 58 #define SBLOCK 2 59 60 /* 61 * The path name on which the file system is mounted is maintained 62 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 63 * the super block for this name. 64 */ 65 #define MAXMNTLEN 512 66 67 /* 68 * Grigoriy Orlov <gluk@ptci.ru> has done some extensive work to fine 69 * tune the layout preferences for directories within a filesystem. 70 * His algorithm can be tuned by adjusting the following parameters 71 * which tell the system the average file size and the average number 72 * of files per directory. These defaults are well selected for typical 73 * filesystems, but may need to be tuned for odd cases like filesystems 74 * being used for squid caches or news spools. 75 * AVFPDIR is the expected number of files per directory. AVGDIRSIZE is 76 * obtained by multiplying AVFPDIR and AVFILESIZ which is assumed to be 77 * 16384. 78 */ 79 80 #define AFPDIR 64 81 #define AVGDIRSIZE 1048576 82 83 /* 84 * Macros for access to superblock array structures 85 */ 86 87 /* 88 * Turn file system block numbers into disk block addresses. 89 * This maps file system blocks to device size blocks. 90 */ 91 #define fsbtodb(fs, b) ((b) << ((fs)->e2fs_fsbtodb)) 92 #define dbtofsb(fs, b) ((b) >> ((fs)->e2fs_fsbtodb)) 93 94 /* get group containing inode */ 95 #define ino_to_cg(fs, x) (((x) - 1) / (fs->e2fs_ipg)) 96 97 /* get block containing inode from its number x */ 98 #define ino_to_fsba(fs, x) \ 99 ((fs)->e2fs_gd[ino_to_cg((fs), (x))].ext2bgd_i_tables + \ 100 (((x) - 1) % (fs)->e2fs->e2fs_ipg) / (fs)->e2fs_ipb) 101 102 /* get offset for inode in block */ 103 #define ino_to_fsbo(fs, x) ((x-1) % (fs->e2fs_ipb)) 104 105 /* 106 * Give cylinder group number for a file system block. 107 * Give cylinder group block number for a file system block. 108 */ 109 #define dtog(fs, d) (((d) - fs->e2fs->e2fs_first_dblock) / \ 110 EXT2_BLOCKS_PER_GROUP(fs)) 111 #define dtogd(fs, d) (((d) - fs->e2fs->e2fs_first_dblock) % \ 112 EXT2_BLOCKS_PER_GROUP(fs)) 113 114 /* 115 * The following macros optimize certain frequently calculated 116 * quantities by using shifts and masks in place of divisions 117 * modulos and multiplications. 118 */ 119 #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \ 120 ((loc) & (fs)->e2fs_qbmask) 121 122 #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \ 123 ((blk) << (fs->e2fs_bshift)) 124 125 #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \ 126 ((loc) >> (fs->e2fs_bshift)) 127 128 /* no fragments -> logical block number equal # of frags */ 129 #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \ 130 ((loc) >> (fs->e2fs_bshift)) 131 132 #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \ 133 roundup(size, fs->e2fs_fsize) 134 /* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */ 135 136 /* 137 * Determining the size of a file block in the file system. 138 * easy w/o fragments 139 */ 140 #define blksize(fs, ip, lbn) ((fs)->e2fs_fsize) 141 142 /* 143 * INOPB is the number of inodes in a secondary storage block. 144 */ 145 #define INOPB(fs) (fs->e2fs_ipb) 146 147 /* 148 * NINDIR is the number of indirects in a file system block. 149 */ 150 #define NINDIR(fs) (EXT2_ADDR_PER_BLOCK(fs)) 151 152 #endif /* !_FS_EXT2FS_FS_H_ */ 153