fs.h revision 330897
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 * 4. 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 * $FreeBSD: stable/11/sys/fs/ext2fs/fs.h 330897 2018-03-14 03:19:51Z eadler $ 39 */ 40 41#ifndef _FS_EXT2FS_FS_H_ 42#define _FS_EXT2FS_FS_H_ 43 44/* 45 * Each disk drive contains some number of file systems. 46 * A file system consists of a number of cylinder groups. 47 * Each cylinder group has inodes and data. 48 * 49 * A file system is described by its super-block, which in turn 50 * describes the cylinder groups. The super-block is critical 51 * data and is replicated in each cylinder group to protect against 52 * catastrophic loss. This is done at `newfs' time and the critical 53 * super-block data does not change, so the copies need not be 54 * referenced further unless disaster strikes. 55 * 56 * The first boot and super blocks are given in absolute disk addresses. 57 * The byte-offset forms are preferred, as they don't imply a sector size. 58 */ 59#define SBSIZE 1024 60#define SBLOCK 2 61 62/* 63 * The path name on which the file system is mounted is maintained 64 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 65 * the super block for this name. 66 */ 67#define MAXMNTLEN 512 68 69/* 70 * A summary of contiguous blocks of various sizes is maintained 71 * in each cylinder group. Normally this is set by the initial 72 * value of fs_maxcontig. 73 * 74 * XXX:FS_MAXCONTIG is set to 16 to conserve space. Here we set 75 * EXT2_MAXCONTIG to 32 for better performance. 76 */ 77#define EXT2_MAXCONTIG 32 78 79/* 80 * Grigoriy Orlov <gluk@ptci.ru> has done some extensive work to fine 81 * tune the layout preferences for directories within a filesystem. 82 * His algorithm can be tuned by adjusting the following parameters 83 * which tell the system the average file size and the average number 84 * of files per directory. These defaults are well selected for typical 85 * filesystems, but may need to be tuned for odd cases like filesystems 86 * being used for squid caches or news spools. 87 * AVFPDIR is the expected number of files per directory. AVGDIRSIZE is 88 * obtained by multiplying AVFPDIR and AVFILESIZ which is assumed to be 89 * 16384. 90 */ 91 92#define AFPDIR 64 93#define AVGDIRSIZE 1048576 94 95/* 96 * Macros for access to superblock array structures 97 */ 98 99/* 100 * Turn file system block numbers into disk block addresses. 101 * This maps file system blocks to device size blocks. 102 */ 103#define fsbtodb(fs, b) ((daddr_t)(b) << (fs)->e2fs_fsbtodb) 104#define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb) 105 106/* get group containing inode */ 107#define ino_to_cg(fs, x) (((x) - 1) / (fs->e2fs_ipg)) 108 109/* get block containing inode from its number x */ 110#define ino_to_fsba(fs, x) \ 111 ((fs)->e2fs_gd[ino_to_cg((fs), (x))].ext2bgd_i_tables + \ 112 (((x) - 1) % (fs)->e2fs->e2fs_ipg) / (fs)->e2fs_ipb) 113 114/* get offset for inode in block */ 115#define ino_to_fsbo(fs, x) ((x-1) % (fs->e2fs_ipb)) 116 117/* 118 * Give cylinder group number for a file system block. 119 * Give cylinder group block number for a file system block. 120 */ 121#define dtog(fs, d) (((d) - fs->e2fs->e2fs_first_dblock) / \ 122 EXT2_BLOCKS_PER_GROUP(fs)) 123#define dtogd(fs, d) (((d) - fs->e2fs->e2fs_first_dblock) % \ 124 EXT2_BLOCKS_PER_GROUP(fs)) 125 126/* 127 * The following macros optimize certain frequently calculated 128 * quantities by using shifts and masks in place of divisions 129 * modulos and multiplications. 130 */ 131#define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \ 132 ((loc) & (fs)->e2fs_qbmask) 133 134#define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \ 135 ((blk) << (fs->e2fs_bshift)) 136 137#define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \ 138 ((loc) >> (fs->e2fs_bshift)) 139 140/* no fragments -> logical block number equal # of frags */ 141#define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \ 142 ((loc) >> (fs->e2fs_bshift)) 143 144#define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \ 145 roundup(size, fs->e2fs_fsize) 146 /* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */ 147 148/* 149 * Determining the size of a file block in the file system. 150 * easy w/o fragments 151 */ 152#define blksize(fs, ip, lbn) ((fs)->e2fs_fsize) 153 154/* 155 * INOPB is the number of inodes in a secondary storage block. 156 */ 157#define INOPB(fs) (fs->e2fs_ipb) 158 159/* 160 * NINDIR is the number of indirects in a file system block. 161 */ 162#define NINDIR(fs) (EXT2_ADDR_PER_BLOCK(fs)) 163 164#endif /* !_FS_EXT2FS_FS_H_ */ 165