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 * SPDX-License-Identifier: BSD-3-Clause 9 * 10 * Copyright (c) 1982, 1986, 1993 11 * The Regents of the University of California. All rights reserved. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)fs.h 8.7 (Berkeley) 4/19/94 38 */ 39 40 #ifndef _FS_EXT2FS_FS_H_ 41 #define _FS_EXT2FS_FS_H_ 42 43 /* 44 * Each disk drive contains some number of file systems. 45 * A file system consists of a number of cylinder groups. 46 * Each cylinder group has inodes and data. 47 * 48 * A file system is described by its super-block, which in turn 49 * describes the cylinder groups. The super-block is critical 50 * data and is replicated in each cylinder group to protect against 51 * catastrophic loss. This is done at `newfs' time and the critical 52 * super-block data does not change, so the copies need not be 53 * referenced further unless disaster strikes. 54 * 55 * The first boot and super blocks are given in absolute disk addresses. 56 * The byte-offset forms are preferred, as they don't imply a sector size. 57 */ 58 #define SBLOCK 0 59 #define SBLOCKSIZE 1024 60 #define SBLOCKOFFSET 1024 61 #define SBLOCKBLKSIZE 4096 62 63 /* 64 * The path name on which the file system is mounted is maintained 65 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 66 * the super block for this name. 67 */ 68 #define MAXMNTLEN 512 69 70 /* 71 * A summary of contiguous blocks of various sizes is maintained 72 * in each cylinder group. Normally this is set by the initial 73 * value of fs_maxcontig. 74 * 75 * XXX:FS_MAXCONTIG is set to 16 to conserve space. Here we set 76 * EXT2_MAXCONTIG to 32 for better performance. 77 */ 78 #define EXT2_MAXCONTIG 32 79 80 /* 81 * Grigoriy Orlov <gluk@ptci.ru> has done some extensive work to fine 82 * tune the layout preferences for directories within a filesystem. 83 * His algorithm can be tuned by adjusting the following parameters 84 * which tell the system the average file size and the average number 85 * of files per directory. These defaults are well selected for typical 86 * filesystems, but may need to be tuned for odd cases like filesystems 87 * being used for squid caches or news spools. 88 * AVFPDIR is the expected number of files per directory. AVGDIRSIZE is 89 * obtained by multiplying AVFPDIR and AVFILESIZ which is assumed to be 90 * 16384. 91 */ 92 93 #define AFPDIR 64 94 #define AVGDIRSIZE 1048576 95 96 /* 97 * Macros for access to superblock array structures 98 */ 99 100 /* 101 * Turn file system block numbers into disk block addresses. 102 * This maps file system blocks to device size blocks. 103 */ 104 #define fsbtodb(fs, b) ((daddr_t)(b) << (fs)->e2fs_fsbtodb) 105 #define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb) 106 107 /* get group containing inode */ 108 #define ino_to_cg(fs, x) (((x) - 1) / (fs->e2fs_ipg)) 109 110 /* get block containing inode from its number x */ 111 #define ino_to_fsba(fs, x) \ 112 (e2fs_gd_get_i_tables(&(fs)->e2fs_gd[ino_to_cg((fs), (x))]) + \ 113 (((x) - 1) % (fs)->e2fs_ipg) / (fs)->e2fs_ipb) 114 115 /* get offset for inode in block */ 116 #define ino_to_fsbo(fs, x) ((x-1) % (fs->e2fs_ipb)) 117 118 /* 119 * Give cylinder group number for a file system block. 120 * Give cylinder group block number for a file system block. 121 */ 122 #define dtog(fs, d) (((d) - le32toh(fs->e2fs->e2fs_first_dblock)) / \ 123 EXT2_BLOCKS_PER_GROUP(fs)) 124 #define dtogd(fs, d) (((d) - le32toh(fs->e2fs->e2fs_first_dblock)) % \ 125 EXT2_BLOCKS_PER_GROUP(fs)) 126 127 /* 128 * The following macros optimize certain frequently calculated 129 * quantities by using shifts and masks in place of divisions 130 * modulos and multiplications. 131 */ 132 #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \ 133 ((loc) & (fs)->e2fs_qbmask) 134 135 #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \ 136 ((blk) << (fs->e2fs_bshift)) 137 138 #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \ 139 ((loc) >> (fs->e2fs_bshift)) 140 141 /* no fragments -> logical block number equal # of frags */ 142 #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \ 143 ((loc) >> (fs->e2fs_bshift)) 144 145 #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \ 146 roundup(size, fs->e2fs_fsize) 147 /* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */ 148 149 /* 150 * Determining the size of a file block in the file system. 151 * easy w/o fragments 152 */ 153 #define blksize(fs, ip, lbn) ((fs)->e2fs_fsize) 154 155 /* 156 * INOPB is the number of inodes in a secondary storage block. 157 */ 158 #define INOPB(fs) (fs->e2fs_ipb) 159 160 /* 161 * NINDIR is the number of indirects in a file system block. 162 */ 163 #define NINDIR(fs) (EXT2_ADDR_PER_BLOCK(fs)) 164 165 /* 166 * Use if additional debug logging is required. 167 */ 168 /* #define EXT2FS_PRINT_EXTENTS */ 169 170 #endif /* !_FS_EXT2FS_FS_H_ */ 171