FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/fs.h
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: releng/9.1/sys/fs/ext2fs/fs.h 229549 2012-01-05 01:35:01Z pfg $
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 extern int inside[], around[];
153 extern u_char *fragtbl[];
154
155 #endif /* !_FS_EXT2FS_FS_H_ */
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