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Diffstat (limited to 'serverboot/fs.h')
| -rw-r--r-- | serverboot/fs.h | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/serverboot/fs.h b/serverboot/fs.h new file mode 100644 index 00000000..5809ed93 --- /dev/null +++ b/serverboot/fs.h @@ -0,0 +1,455 @@ +/* + * 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 ((off_t)(0)) +#define SBOFF ((off_t)(BBOFF + BBSIZE)) +#define BBLOCK ((daddr_t)(0)) +#define SBLOCK ((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 ((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;*/ + daddr_t fs_sblkno; /* addr of super-block in filesys */ + daddr_t fs_cblkno; /* offset of cyl-block in filesys */ + daddr_t fs_iblkno; /* offset of inode-blocks in filesys */ + 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 */ + 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 */ + 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 */ + 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;*/ + 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) ((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) \ + ((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) + |