/* * Mach Operating System * Copyright (c) 1991,1990 Carnegie Mellon University * All Rights Reserved. * * Permission to use, copy, modify and distribute this software and its * documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie Mellon * the rights to redistribute these changes. */ /* * Copyright (c) 1982, 1986 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by the University of California, Berkeley. The name of the * University may not be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * @(#)fs.h 7.7 (Berkeley) 5/9/89 */ /* * 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. * * For file system fs, the offsets of the various blocks of interest * are given in the super block as: * [fs->fs_sblkno] Super-block * [fs->fs_cblkno] Cylinder group block * [fs->fs_iblkno] Inode blocks * [fs->fs_dblkno] Data blocks * The beginning of cylinder group cg in fs, is given by * the ``cgbase(fs, cg)'' macro. * * 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 BBSIZE 8192 #define SBSIZE 8192 #define BBOFF ((mach_off_t)(0)) #define SBOFF ((mach_off_t)(BBOFF + BBSIZE)) #define BBLOCK ((mach_daddr_t)(0)) #define SBLOCK ((mach_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE)) /* * Addresses stored in inodes are capable of addressing fragments * of `blocks'. File system blocks of at most size MAXBSIZE can * be optionally broken into 2, 4, or 8 pieces, each of which is * addressible; these pieces may be DEV_BSIZE, or some multiple of * a DEV_BSIZE unit. * * Large files consist of exclusively large data blocks. To avoid * undue wasted disk space, the last data block of a small file may be * allocated as only as many fragments of a large block as are * necessary. The file system format retains only a single pointer * to such a fragment, which is a piece of a single large block that * has been divided. The size of such a fragment is determinable from * information in the inode, using the ``blksize(fs, ip, lbn)'' macro. * * The file system records space availability at the fragment level; * to determine block availability, aligned fragments are examined. * * The root inode is the root of the file system. * Inode 0 can't be used for normal purposes and * historically bad blocks were linked to inode 1, * thus the root inode is 2. (inode 1 is no longer used for * this purpose, however numerous dump tapes make this * assumption, so we are stuck with it) */ #define ROOTINO ((mach_ino_t)2) /* i number of all roots */ /* * MINBSIZE is the smallest allowable block size. * In order to insure that it is possible to create files of size * 2^32 with only two levels of indirection, MINBSIZE is set to 4096. * MINBSIZE must be big enough to hold a cylinder group block, * thus changes to (struct cg) must keep its size within MINBSIZE. * Note that super blocks are always of size SBSIZE, * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. */ #define MINBSIZE 4096 /* * 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. * The limit on the amount of summary information per file system * is defined by MAXCSBUFS. It is currently parameterized for a * maximum of two million cylinders. */ #define MAXMNTLEN 512 #define MAXCSBUFS 32 /* * Per cylinder group information; summarized in blocks allocated * from first cylinder group data blocks. These blocks have to be * read in from fs_csaddr (size fs_cssize) in addition to the * super block. * * N.B. sizeof(struct csum) must be a power of two in order for * the ``fs_cs'' macro to work (see below). */ struct csum { int cs_ndir; /* number of directories */ int cs_nbfree; /* number of free blocks */ int cs_nifree; /* number of free inodes */ int cs_nffree; /* number of free frags */ }; /* * Super block for a file system. */ #define FS_MAGIC 0x011954 struct fs { int xxx1; /* struct fs *fs_link; */ int xxx2; /* struct fs *fs_rlink; */ mach_daddr_t fs_sblkno; /* addr of super-block in filesys */ mach_daddr_t fs_cblkno; /* offset of cyl-block in filesys */ mach_daddr_t fs_iblkno; /* offset of inode-blocks in filesys */ mach_daddr_t fs_dblkno; /* offset of first data after cg */ int fs_cgoffset; /* cylinder group offset in cylinder */ int fs_cgmask; /* used to calc mod fs_ntrak */ mach_time_t fs_time; /* last time written */ int fs_size; /* number of blocks in fs */ int fs_dsize; /* number of data blocks in fs */ int fs_ncg; /* number of cylinder groups */ int fs_bsize; /* size of basic blocks in fs */ int fs_fsize; /* size of frag blocks in fs */ int fs_frag; /* number of frags in a block in fs */ /* these are configuration parameters */ int fs_minfree; /* minimum percentage of free blocks */ int fs_rotdelay; /* num of ms for optimal next block */ int fs_rps; /* disk revolutions per second */ /* these fields can be computed from the others */ int fs_bmask; /* ``blkoff'' calc of blk offsets */ int fs_fmask; /* ``fragoff'' calc of frag offsets */ int fs_bshift; /* ``lblkno'' calc of logical blkno */ int fs_fshift; /* ``numfrags'' calc number of frags */ /* these are configuration parameters */ int fs_maxcontig; /* max number of contiguous blks */ int fs_maxbpg; /* max number of blks per cyl group */ /* these fields can be computed from the others */ int fs_fragshift; /* block to frag shift */ int fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ int fs_sbsize; /* actual size of super block */ int fs_csmask; /* csum block offset */ int fs_csshift; /* csum block number */ int fs_nindir; /* value of NINDIR */ int fs_inopb; /* value of INOPB */ int fs_nspf; /* value of NSPF */ /* yet another configuration parameter */ int fs_optim; /* optimization preference, see below */ /* these fields are derived from the hardware */ int fs_npsect; /* # sectors/track including spares */ int fs_interleave; /* hardware sector interleave */ int fs_trackskew; /* sector 0 skew, per track */ int fs_headswitch; /* head switch time, usec */ int fs_trkseek; /* track-to-track seek, usec */ /* sizes determined by number of cylinder groups and their sizes */ mach_daddr_t fs_csaddr; /* blk addr of cyl grp summary area */ int fs_cssize; /* size of cyl grp summary area */ int fs_cgsize; /* cylinder group size */ /* these fields are derived from the hardware */ int fs_ntrak; /* tracks per cylinder */ int fs_nsect; /* sectors per track */ int fs_spc; /* sectors per cylinder */ /* this comes from the disk driver partitioning */ int fs_ncyl; /* cylinders in file system */ /* these fields can be computed from the others */ int fs_cpg; /* cylinders per group */ int fs_ipg; /* inodes per group */ int fs_fpg; /* blocks per group * fs_frag */ /* this data must be re-computed after crashes */ struct csum fs_cstotal; /* cylinder summary information */ /* these fields are cleared at mount time */ char fs_fmod; /* super block modified flag */ char fs_clean; /* file system is clean flag */ char fs_ronly; /* mounted read-only flag */ char fs_flags; /* currently unused flag */ char fs_fsmnt[MAXMNTLEN]; /* name mounted on */ /* these fields retain the current block allocation info */ int fs_cgrotor; /* last cg searched */ #if 1 int was_fs_csp[MAXCSBUFS]; #else struct csum *fs_csp[MAXCSBUFS]; /* list of fs_cs info buffers */ #endif int fs_cpc; /* cyl per cycle in postbl */ short fs_opostbl[16][8]; /* old rotation block list head */ long fs_sparecon[50]; /* reserved for future constants */ long fs_contigsumsize; /* size of cluster summary array */ long fs_maxsymlinklen; /* max length of an internal symlink */ long fs_inodefmt; /* format of on-disk inodes */ quad fs_maxfilesize; /* maximum representable file size */ quad fs_qbmask; /* ~fs_bmask - for use with quad size */ quad fs_qfmask; /* ~fs_fmask - for use with quad size */ long fs_state; /* validate fs_clean field */ int fs_postblformat; /* format of positional layout tables */ int fs_nrpos; /* number of rotaional positions */ int fs_postbloff; /* (short) rotation block list head */ int fs_rotbloff; /* (u_char) blocks for each rotation */ int fs_magic; /* magic number */ u_char fs_space[1]; /* list of blocks for each rotation */ /* actually longer */ }; /* * Preference for optimization. */ #define FS_OPTTIME 0 /* minimize allocation time */ #define FS_OPTSPACE 1 /* minimize disk fragmentation */ /* * Rotational layout table format types */ #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */ #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */ /* * Macros for access to superblock array structures */ #define fs_postbl(fs, cylno) \ (((fs)->fs_postblformat == FS_42POSTBLFMT) \ ? ((fs)->fs_opostbl[cylno]) \ : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos)) #define fs_rotbl(fs) \ (((fs)->fs_postblformat == FS_42POSTBLFMT) \ ? ((fs)->fs_space) \ : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff))) /* * Convert cylinder group to base address of its global summary info. * * N.B. This macro assumes that sizeof(struct csum) is a power of two. */ #define fs_cs(fs, indx) \ fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask] /* * Cylinder group block for a file system. */ #define CG_MAGIC 0x090255 struct cg { int xxx1; /* struct cg *cg_link; */ int cg_magic; /* magic number */ mach_time_t cg_time; /* time last written */ int cg_cgx; /* we are the cgx'th cylinder group */ short cg_ncyl; /* number of cyl's this cg */ short cg_niblk; /* number of inode blocks this cg */ int cg_ndblk; /* number of data blocks this cg */ struct csum cg_cs; /* cylinder summary information */ int cg_rotor; /* position of last used block */ int cg_frotor; /* position of last used frag */ int cg_irotor; /* position of last used inode */ int cg_frsum[MAXFRAG]; /* counts of available frags */ int cg_btotoff; /* (long) block totals per cylinder */ int cg_boff; /* (short) free block positions */ int cg_iusedoff; /* (char) used inode map */ int cg_freeoff; /* (u_char) free block map */ int cg_nextfreeoff; /* (u_char) next available space */ int cg_sparecon[16]; /* reserved for future use */ u_char cg_space[1]; /* space for cylinder group maps */ /* actually longer */ }; /* * Macros for access to cylinder group array structures */ #define cg_blktot(cgp) \ (((cgp)->cg_magic != CG_MAGIC) \ ? (((struct ocg *)(cgp))->cg_btot) \ : ((int *)((char *)(cgp) + (cgp)->cg_btotoff))) #define cg_blks(fs, cgp, cylno) \ (((cgp)->cg_magic != CG_MAGIC) \ ? (((struct ocg *)(cgp))->cg_b[cylno]) \ : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos)) #define cg_inosused(cgp) \ (((cgp)->cg_magic != CG_MAGIC) \ ? (((struct ocg *)(cgp))->cg_iused) \ : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff))) #define cg_blksfree(cgp) \ (((cgp)->cg_magic != CG_MAGIC) \ ? (((struct ocg *)(cgp))->cg_free) \ : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff))) #define cg_chkmagic(cgp) \ ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC) /* * The following structure is defined * for compatibility with old file systems. */ struct ocg { int xxx1; /* struct ocg *cg_link; */ int xxx2; /* struct ocg *cg_rlink; */ mach_time_t cg_time; /* time last written */ int cg_cgx; /* we are the cgx'th cylinder group */ short cg_ncyl; /* number of cyl's this cg */ short cg_niblk; /* number of inode blocks this cg */ int cg_ndblk; /* number of data blocks this cg */ struct csum cg_cs; /* cylinder summary information */ int cg_rotor; /* position of last used block */ int cg_frotor; /* position of last used frag */ int cg_irotor; /* position of last used inode */ int cg_frsum[8]; /* counts of available frags */ int cg_btot[32]; /* block totals per cylinder */ short cg_b[32][8]; /* positions of free blocks */ char cg_iused[256]; /* used inode map */ int cg_magic; /* magic number */ u_char cg_free[1]; /* free block map */ /* actually longer */ }; /* * Turn file system block numbers into disk block addresses. * This maps file system blocks to device size blocks. */ #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb) #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb) /* * Cylinder group macros to locate things in cylinder groups. * They calc file system addresses of cylinder group data structures. */ #define cgbase(fs, c) ((mach_daddr_t)((fs)->fs_fpg * (c))) #define cgstart(fs, c) \ (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask))) #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */ #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */ #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */ #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */ /* * Macros for handling inode numbers: * inode number to file system block offset. * inode number to cylinder group number. * inode number to file system block address. */ #define itoo(fs, x) ((x) % INOPB(fs)) #define itog(fs, x) ((x) / (fs)->fs_ipg) #define itod(fs, x) \ ((mach_daddr_t)(cgimin(fs, itog(fs, x)) + \ (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs)))))) /* * 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)->fs_fpg) #define dtogd(fs, d) ((d) % (fs)->fs_fpg) /* * Extract the bits for a block from a map. * Compute the cylinder and rotational position of a cyl block addr. */ #define blkmap(fs, map, loc) \ (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag))) #define cbtocylno(fs, bno) \ ((bno) * NSPF(fs) / (fs)->fs_spc) #define cbtorpos(fs, bno) \ (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \ (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \ (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect) /* * 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)->fs_bmask) #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \ ((loc) & ~(fs)->fs_fmask) #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \ ((loc) >> (fs)->fs_bshift) #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \ ((loc) >> (fs)->fs_fshift) #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \ (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask) #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \ (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask) #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \ ((frags) >> (fs)->fs_fragshift) #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \ ((blks) << (fs)->fs_fragshift) #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \ ((fsb) & ((fs)->fs_frag - 1)) #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \ ((fsb) &~ ((fs)->fs_frag - 1)) /* * Determine the number of available frags given a * percentage to hold in reserve */ #define freespace(fs, percentreserved) \ (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \ (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100)) /* * Determining the size of a file block in the file system. */ #define blksize(fs, ip, lbn) \ (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \ ? (fs)->fs_bsize \ : (fragroundup(fs, blkoff(fs, (ip)->i_size)))) #define dblksize(fs, dip, lbn) \ (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \ ? (fs)->fs_bsize \ : (fragroundup(fs, blkoff(fs, (dip)->di_size)))) /* * Number of disk sectors per block; assumes DEV_BSIZE byte sector size. */ #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift) #define NSPF(fs) ((fs)->fs_nspf) /* * INOPB is the number of inodes in a secondary storage block. */ #define INOPB(fs) ((fs)->fs_inopb) #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift) /* * NINDIR is the number of indirects in a file system block. */ #define NINDIR(fs) ((fs)->fs_nindir)