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C/C++ Source or Header | 1995-02-15 | 18.0 KB | 484 lines

/* * Mach Operating System * Copyright (c) 1987 Carnegie-Mellon University * All rights reserved. The CMU software License Agreement specifies * the terms and conditions for use and redistribution. */ /* * HISTORY * 27-Sep-89 Morris Meyer (mmeyer) at NeXT * NFS 4.0 Changes. * * 25-Jan-86 Avadis Tevanian (avie) at Carnegie-Mellon University * Upgraded to 4.3. * * 03-Aug-85 Mike Accetta (mja) at Carnegie-Mellon University * CS_RPAUSE: Added freefrags() and freeinodes() macros and * FS_FLOWAT, FS_FHIWAT, FS_ILOWAT, FS_IHIWAT, FS_FNOSPC and * FS_INOSPC definitions. * */ /* * Copyright (c) 1982, 1986 Regents of the University of California. * All rights reserved. The Berkeley software License Agreement * specifies the terms and conditions for redistribution. * * @(#)fs.h 7.1 (Berkeley) 6/4/86 */ /* @(#)fs.h 2.1 88/05/20 4.0NFSSRC SMI; from UCB 7.1 6/4/86 */ /* * 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 mkfs 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. */ #define BBSIZE 8192 #define SBSIZE 8192 #define BBLOCK ((daddr_t)(0)) #if NeXT /* * SBLOCK gives the address in bytes. It's up to code to convert to * device blocks based on the blocksize of the device... */ #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE)) #else NeXT #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE) / DEV_BSIZE) #endif NeXT /* * 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) * The lost+found directory is given the next available * inode when it is created by ``mkfs''. */ #define ROOTINO ((ino_t)2) /* i number of all roots */ #define LOSTFOUNDINO (ROOTINO + 1) /* * Cylinder group related limits. * * For each cylinder we keep track of the availability of blocks at different * rotational positions, so that we can lay out the data to be picked * up with minimum rotational latency. NRPOS is the number of rotational * positions which we distinguish. With NRPOS 8 the resolution of our * summary information is 2ms for a typical 3600 rpm drive. */ #define NRPOS 8 /* number distinct rotational positions */ /* * MAXIPG bounds the number of inodes per cylinder group, and * is needed only to keep the structure simpler by having the * only a single variable size element (the free bit map). * * N.B.: MAXIPG must be a multiple of INOPB(fs). */ #define MAXIPG 2048 /* max number inodes/cyl group */ /* * 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. * MAXCPG is limited only to dimension an array in (struct cg); * it can be made larger as long as that structures size remains * within the bounds dictated by MINBSIZE. * Note that super blocks are always of size SBSIZE, * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. */ #define MINBSIZE 4096 #define MAXCPG 32 /* maximum fs_cpg */ /* * 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 { long cs_ndir; /* number of directories */ long cs_nbfree; /* number of free blocks */ long cs_nifree; /* number of free inodes */ long cs_nffree; /* number of free frags */ }; /* * Super block for a file system. */ #define FS_MAGIC 0x011954 struct fs { struct fs *fs_link; /* linked list of file systems */ struct fs *fs_rlink; /* used for incore super blocks */ 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 */ long fs_cgoffset; /* cylinder group offset in cylinder */ long fs_cgmask; /* used to calc mod fs_ntrak */ time_t fs_time; /* last time written */ long fs_size; /* number of blocks in fs */ long fs_dsize; /* number of data blocks in fs */ long fs_ncg; /* number of cylinder groups */ long fs_bsize; /* size of basic blocks in fs */ long fs_fsize; /* size of frag blocks in fs */ long fs_frag; /* number of frags in a block in fs */ /* these are configuration parameters */ long fs_minfree; /* minimum percentage of free blocks */ long fs_rotdelay; /* num of ms for optimal next block */ long fs_rps; /* disk revolutions per second */ /* these fields can be computed from the others */ long fs_bmask; /* ``blkoff'' calc of blk offsets */ long fs_fmask; /* ``fragoff'' calc of frag offsets */ long fs_bshift; /* ``lblkno'' calc of logical blkno */ long fs_fshift; /* ``numfrags'' calc number of frags */ /* these are configuration parameters */ long fs_maxcontig; /* max number of contiguous blks */ long fs_maxbpg; /* max number of blks per cyl group */ /* these fields can be computed from the others */ long fs_fragshift; /* block to frag shift */ long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ long fs_sbsize; /* actual size of super block */ long fs_csmask; /* csum block offset */ long fs_csshift; /* csum block number */ long fs_nindir; /* value of NINDIR */ long fs_inopb; /* value of INOPB */ long fs_nspf; /* value of NSPF */ long fs_optim; /* optimization preference, see below */ /* BEGIN CS_RPAUSE */ /* * This entire structure appears on the disk in new file systems * and the in-core version is the primary handle which is passed * around internally. We need space for a pointer to the old * format super-block for such file systems and this is as good as * any. We could also share space with any field used by the new * file system which is not needed in the common path processing * code for both file systems but this seems safer. */ union { long sufs_sparecon[5]; /* reserved for future constants */ } fs_spareun; #define fs_fhiwat fs_spareun.sufs_sparecon[1] /* fragment high water mark */ #define fs_flowat fs_spareun.sufs_sparecon[2] /* fragment low water mark */ #define fs_ihiwat fs_spareun.sufs_sparecon[3] /* inode high water mark */ #define fs_ilowat fs_spareun.sufs_sparecon[4] /* inode low water mark */ #define fs_sparecon fs_spareun.sufs_sparecon /* END CS_RPAUSE */ /* sizes determined by number of cylinder groups and their sizes */ daddr_t fs_csaddr; /* blk addr of cyl grp summary area */ long fs_cssize; /* size of cyl grp summary area */ long fs_cgsize; /* cylinder group size */ /* these fields should be derived from the hardware */ long fs_ntrak; /* tracks per cylinder */ long fs_nsect; /* sectors per track */ long fs_spc; /* sectors per cylinder */ /* this comes from the disk driver partitioning */ long fs_ncyl; /* cylinders in file system */ /* these fields can be computed from the others */ long fs_cpg; /* cylinders per group */ long fs_ipg; /* inodes per group */ long 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 */ #ifdef NeXT char fs_state; /* file system state (clean,...) */ #else NeXT char fs_clean; /* super block clean flag */ #endif NeXT 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 */ long fs_cgrotor; /* last cg searched */ struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */ long fs_cpc; /* cyl per cycle in postbl */ short fs_postbl[MAXCPG][NRPOS];/* head of blocks for each rotation */ long fs_magic; /* magic number */ u_char fs_rotbl[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 */ #ifdef NeXT /* * File system states. * * A cleanly unmounted FS goes to clean state if it was in dirty * state. Mounting a clean FS makes it dirty. Mounting a dirty FS * makes it corrupted. fsck (or equivalent) will change a dirty or * corrupted FS to clean state. NOTE: a FS that has never had this * state set (state == 0) will be treated as corrupted. */ #define FS_STATE_CLEAN 1 /* cleanly unmounted */ #define FS_STATE_DIRTY 2 /* dirty */ #define FS_STATE_CORRUPTED 3 /* mounted while dirty */ #endif NeXT /* * 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] /* * MAXBPC bounds the size of the rotational layout tables and * is limited by the fact that the super block is of size SBSIZE. * The size of these tables is INVERSELY proportional to the block * size of the file system. It is aggravated by sector sizes that * are not powers of two, as this increases the number of cylinders * included before the rotational pattern repeats (fs_cpc). * Its size is derived from the number of bytes remaining in (struct fs) */ #define MAXBPC (SBSIZE - sizeof (struct fs)) /* * Cylinder group block for a file system. */ #define CG_MAGIC 0x090255 struct cg { struct cg *cg_link; /* linked list of cyl groups */ struct cg *cg_rlink; /* used for incore cyl groups */ time_t cg_time; /* time last written */ long 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 */ long cg_ndblk; /* number of data blocks this cg */ struct csum cg_cs; /* cylinder summary information */ long cg_rotor; /* position of last used block */ long cg_frotor; /* position of last used frag */ long cg_irotor; /* position of last used inode */ long cg_frsum[MAXFRAG]; /* counts of available frags */ long cg_btot[MAXCPG]; /* block totals per cylinder */ short cg_b[MAXCPG][NRPOS]; /* positions of free blocks */ char cg_iused[MAXIPG/NBBY]; /* used inode map */ long cg_magic; /* magic number */ u_char cg_free[1]; /* free block map */ /* actually longer */ }; /* * MAXBPG bounds the number of blocks of data per cylinder group, * and is limited by the fact that cylinder groups are at most one block. * Its size is derived from the size of blocks and the (struct cg) size, * by the number of remaining bits. */ #define MAXBPG(fs) \ (fragstoblks((fs), (NBBY * ((fs)->fs_bsize - (sizeof (struct cg)))))) /* * 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 * NRPOS / (fs)->fs_nsect) /* * 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)) /* BEGIN CS_RPAUSE */ /* * Low fragment/inode space flag bits. */ #define FS_FNOSPC 1 /* low on fragments */ #define FS_INOSPC 2 /* low on inodes */ /* * Free fragment/inode high/low water mark definitions. */ #define FS_FLOWAT(fs) ((fs)->fs_flowat) /* fragment low water */ #define FS_FHIWAT(fs) ((fs)->fs_fhiwat) /* fragment high water */ #define FS_ILOWAT(fs) ((fs)->fs_ilowat) /* inode low water */ #define FS_IHIWAT(fs) ((fs)->fs_ihiwat) /* inode high water */ /* * Determine the absolute number of available inodes */ #define freeinodes(fs) \ ( \ ((fs)->fs_cstotal.cs_nifree) \ ) /* * Determine the absolute number of available frags. */ #define freefrags(fs) \ ( \ blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) \ + \ (fs)->fs_cstotal.cs_nffree \ ) /* END CS_RPAUSE */ /* * 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) #if NeXT /* * This macro controls whether the file system format is byte swapped or not. * At NeXT, all little endian machines read and write big endian file systems. */ #define BIG_ENDIAN_FS (__LITTLE_ENDIAN__) #endif NeXT