* modified for EXT2FS support in Lites 1.1
* Aug 1995, Godmar Back (email@example.com)
* University of Utah, Department of Computer Science
* 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.
* 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
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* SUCH DAMAGE.
* @(#)fs.h 8.7 (Berkeley) 4/19/94
* $FreeBSD: head/sys/fs/ext2fs/fs.h 262623 2014-02-28 21:25:32Z pfg $
* 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 SBSIZE 1024
#define SBLOCK 2
* 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
* A summary of contiguous blocks of various sizes is maintained
* in each cylinder group. Normally this is set by the initial
* value of fs_maxcontig.
* XXX:FS_MAXCONTIG is set to 16 to conserve space. Here we set
* EXT2_MAXCONTIG to 32 for better performance.
#define EXT2_MAXCONTIG 32
* Grigoriy Orlov <firstname.lastname@example.org> has done some extensive work to fine
* tune the layout preferences for directories within a filesystem.
* His algorithm can be tuned by adjusting the following parameters
* which tell the system the average file size and the average number
* of files per directory. These defaults are well selected for typical
* filesystems, but may need to be tuned for odd cases like filesystems
* being used for squid caches or news spools.
* AVFPDIR is the expected number of files per directory. AVGDIRSIZE is
* obtained by multiplying AVFPDIR and AVFILESIZ which is assumed to be
#define AFPDIR 64
#define AVGDIRSIZE 1048576
* Macros for access to superblock array structures
* Turn file system block numbers into disk block addresses.
* This maps file system blocks to device size blocks.
#define fsbtodb(fs, b) ((daddr_t)(b) << (fs)->e2fs_fsbtodb)
#define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb)
/* get group containing inode */
#define ino_to_cg(fs, x) (((x) - 1) / (fs->e2fs_ipg))
/* get block containing inode from its number x */
#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)
/* get offset for inode in block */
#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) / \
#define dtogd(fs, d) (((d) - fs->e2fs->e2fs_first_dblock) % \
* 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->fs_bsize) */ \
((loc) & (fs)->e2fs_qbmask)
#define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
((blk) << (fs->e2fs_bshift))
#define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
((loc) >> (fs->e2fs_bshift))
/* no fragments -> logical block number equal # of frags */
#define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
((loc) >> (fs->e2fs_bshift))
#define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
/* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */
* Determining the size of a file block in the file system.
* easy w/o fragments
#define blksize(fs, ip, lbn) ((fs)->e2fs_fsize)
* INOPB is the number of inodes in a secondary storage block.
#define INOPB(fs) (fs->e2fs_ipb)
* NINDIR is the number of indirects in a file system block.
#define NINDIR(fs) (EXT2_ADDR_PER_BLOCK(fs))
#endif /* !_FS_EXT2FS_FS_H_ */