1 /* 2 * Copyright (c) 1982, 1986, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)fs.h 8.1 (Berkeley) 06/11/93 8 */ 9 10 /* 11 * Each disk drive contains some number of file systems. 12 * A file system consists of a number of cylinder groups. 13 * Each cylinder group has inodes and data. 14 * 15 * A file system is described by its super-block, which in turn 16 * describes the cylinder groups. The super-block is critical 17 * data and is replicated in each cylinder group to protect against 18 * catastrophic loss. This is done at `newfs' time and the critical 19 * super-block data does not change, so the copies need not be 20 * referenced further unless disaster strikes. 21 * 22 * For file system fs, the offsets of the various blocks of interest 23 * are given in the super block as: 24 * [fs->fs_sblkno] Super-block 25 * [fs->fs_cblkno] Cylinder group block 26 * [fs->fs_iblkno] Inode blocks 27 * [fs->fs_dblkno] Data blocks 28 * The beginning of cylinder group cg in fs, is given by 29 * the ``cgbase(fs, cg)'' macro. 30 * 31 * The first boot and super blocks are given in absolute disk addresses. 32 * The byte-offset forms are preferred, as they don't imply a sector size. 33 */ 34 #define BBSIZE 8192 35 #define SBSIZE 8192 36 #define BBOFF ((off_t)(0)) 37 #define SBOFF ((off_t)(BBOFF + BBSIZE)) 38 #define BBLOCK ((daddr_t)(0)) 39 #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE)) 40 41 /* 42 * Addresses stored in inodes are capable of addressing fragments 43 * of `blocks'. File system blocks of at most size MAXBSIZE can 44 * be optionally broken into 2, 4, or 8 pieces, each of which is 45 * addressible; these pieces may be DEV_BSIZE, or some multiple of 46 * a DEV_BSIZE unit. 47 * 48 * Large files consist of exclusively large data blocks. To avoid 49 * undue wasted disk space, the last data block of a small file may be 50 * allocated as only as many fragments of a large block as are 51 * necessary. The file system format retains only a single pointer 52 * to such a fragment, which is a piece of a single large block that 53 * has been divided. The size of such a fragment is determinable from 54 * information in the inode, using the ``blksize(fs, ip, lbn)'' macro. 55 * 56 * The file system records space availability at the fragment level; 57 * to determine block availability, aligned fragments are examined. 58 */ 59 60 /* 61 * MINBSIZE is the smallest allowable block size. 62 * In order to insure that it is possible to create files of size 63 * 2^32 with only two levels of indirection, MINBSIZE is set to 4096. 64 * MINBSIZE must be big enough to hold a cylinder group block, 65 * thus changes to (struct cg) must keep its size within MINBSIZE. 66 * Note that super blocks are always of size SBSIZE, 67 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. 68 */ 69 #define MINBSIZE 4096 70 71 /* 72 * The path name on which the file system is mounted is maintained 73 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 74 * the super block for this name. 75 * The limit on the amount of summary information per file system 76 * is defined by MAXCSBUFS. It is currently parameterized for a 77 * maximum of two million cylinders. 78 */ 79 #define MAXMNTLEN 512 80 #define MAXCSBUFS 32 81 82 /* 83 * Per cylinder group information; summarized in blocks allocated 84 * from first cylinder group data blocks. These blocks have to be 85 * read in from fs_csaddr (size fs_cssize) in addition to the 86 * super block. 87 * 88 * N.B. sizeof(struct csum) must be a power of two in order for 89 * the ``fs_cs'' macro to work (see below). 90 */ 91 struct csum { 92 long cs_ndir; /* number of directories */ 93 long cs_nbfree; /* number of free blocks */ 94 long cs_nifree; /* number of free inodes */ 95 long cs_nffree; /* number of free frags */ 96 }; 97 98 /* 99 * Super block for a file system. 100 */ 101 struct fs { 102 struct fs *fs_link; /* linked list of file systems */ 103 struct fs *fs_rlink; /* used for incore super blocks */ 104 daddr_t fs_sblkno; /* addr of super-block in filesys */ 105 daddr_t fs_cblkno; /* offset of cyl-block in filesys */ 106 daddr_t fs_iblkno; /* offset of inode-blocks in filesys */ 107 daddr_t fs_dblkno; /* offset of first data after cg */ 108 long fs_cgoffset; /* cylinder group offset in cylinder */ 109 long fs_cgmask; /* used to calc mod fs_ntrak */ 110 time_t fs_time; /* last time written */ 111 long fs_size; /* number of blocks in fs */ 112 long fs_dsize; /* number of data blocks in fs */ 113 long fs_ncg; /* number of cylinder groups */ 114 long fs_bsize; /* size of basic blocks in fs */ 115 long fs_fsize; /* size of frag blocks in fs */ 116 long fs_frag; /* number of frags in a block in fs */ 117 /* these are configuration parameters */ 118 long fs_minfree; /* minimum percentage of free blocks */ 119 long fs_rotdelay; /* num of ms for optimal next block */ 120 long fs_rps; /* disk revolutions per second */ 121 /* these fields can be computed from the others */ 122 long fs_bmask; /* ``blkoff'' calc of blk offsets */ 123 long fs_fmask; /* ``fragoff'' calc of frag offsets */ 124 long fs_bshift; /* ``lblkno'' calc of logical blkno */ 125 long fs_fshift; /* ``numfrags'' calc number of frags */ 126 /* these are configuration parameters */ 127 long fs_maxcontig; /* max number of contiguous blks */ 128 long fs_maxbpg; /* max number of blks per cyl group */ 129 /* these fields can be computed from the others */ 130 long fs_fragshift; /* block to frag shift */ 131 long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ 132 long fs_sbsize; /* actual size of super block */ 133 long fs_csmask; /* csum block offset */ 134 long fs_csshift; /* csum block number */ 135 long fs_nindir; /* value of NINDIR */ 136 long fs_inopb; /* value of INOPB */ 137 long fs_nspf; /* value of NSPF */ 138 /* yet another configuration parameter */ 139 long fs_optim; /* optimization preference, see below */ 140 /* these fields are derived from the hardware */ 141 long fs_npsect; /* # sectors/track including spares */ 142 long fs_interleave; /* hardware sector interleave */ 143 long fs_trackskew; /* sector 0 skew, per track */ 144 long fs_headswitch; /* head switch time, usec */ 145 long fs_trkseek; /* track-to-track seek, usec */ 146 /* sizes determined by number of cylinder groups and their sizes */ 147 daddr_t fs_csaddr; /* blk addr of cyl grp summary area */ 148 long fs_cssize; /* size of cyl grp summary area */ 149 long fs_cgsize; /* cylinder group size */ 150 /* these fields are derived from the hardware */ 151 long fs_ntrak; /* tracks per cylinder */ 152 long fs_nsect; /* sectors per track */ 153 long fs_spc; /* sectors per cylinder */ 154 /* this comes from the disk driver partitioning */ 155 long fs_ncyl; /* cylinders in file system */ 156 /* these fields can be computed from the others */ 157 long fs_cpg; /* cylinders per group */ 158 long fs_ipg; /* inodes per group */ 159 long fs_fpg; /* blocks per group * fs_frag */ 160 /* this data must be re-computed after crashes */ 161 struct csum fs_cstotal; /* cylinder summary information */ 162 /* these fields are cleared at mount time */ 163 char fs_fmod; /* super block modified flag */ 164 char fs_clean; /* file system is clean flag */ 165 char fs_ronly; /* mounted read-only flag */ 166 char fs_flags; /* currently unused flag */ 167 char fs_fsmnt[MAXMNTLEN]; /* name mounted on */ 168 /* these fields retain the current block allocation info */ 169 long fs_cgrotor; /* last cg searched */ 170 struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */ 171 long fs_cpc; /* cyl per cycle in postbl */ 172 short fs_opostbl[16][8]; /* old rotation block list head */ 173 long fs_sparecon[51]; /* reserved for future constants */ 174 long fs_maxsymlinklen; /* max length of an internal symlink */ 175 long fs_inodefmt; /* format of on-disk inodes */ 176 u_quad_t fs_maxfilesize; /* maximum representable file size */ 177 quad_t fs_qbmask; /* ~fs_bmask - for use with quad size */ 178 quad_t fs_qfmask; /* ~fs_fmask - for use with quad size */ 179 long fs_state; /* validate fs_clean field */ 180 long fs_postblformat; /* format of positional layout tables */ 181 long fs_nrpos; /* number of rotaional positions */ 182 long fs_postbloff; /* (short) rotation block list head */ 183 long fs_rotbloff; /* (u_char) blocks for each rotation */ 184 long fs_magic; /* magic number */ 185 u_char fs_space[1]; /* list of blocks for each rotation */ 186 /* actually longer */ 187 }; 188 /* 189 * Filesystem idetification 190 */ 191 #define FS_MAGIC 0x011954 /* the fast filesystem magic number */ 192 #define FS_OKAY 0x7c269d38 /* superblock checksum */ 193 #define FS_42INODEFMT -1 /* 4.2BSD inode format */ 194 #define FS_44INODEFMT 2 /* 4.4BSD inode format */ 195 /* 196 * Preference for optimization. 197 */ 198 #define FS_OPTTIME 0 /* minimize allocation time */ 199 #define FS_OPTSPACE 1 /* minimize disk fragmentation */ 200 201 /* 202 * Rotational layout table format types 203 */ 204 #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */ 205 #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */ 206 /* 207 * Macros for access to superblock array structures 208 */ 209 #define fs_postbl(fs, cylno) \ 210 (((fs)->fs_postblformat == FS_42POSTBLFMT) \ 211 ? ((fs)->fs_opostbl[cylno]) \ 212 : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos)) 213 #define fs_rotbl(fs) \ 214 (((fs)->fs_postblformat == FS_42POSTBLFMT) \ 215 ? ((fs)->fs_space) \ 216 : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff))) 217 218 /* 219 * Convert cylinder group to base address of its global summary info. 220 * 221 * N.B. This macro assumes that sizeof(struct csum) is a power of two. 222 */ 223 #define fs_cs(fs, indx) \ 224 fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask] 225 226 /* 227 * Cylinder group block for a file system. 228 */ 229 #define CG_MAGIC 0x090255 230 struct cg { 231 struct cg *cg_link; /* linked list of cyl groups */ 232 long cg_magic; /* magic number */ 233 time_t cg_time; /* time last written */ 234 long cg_cgx; /* we are the cgx'th cylinder group */ 235 short cg_ncyl; /* number of cyl's this cg */ 236 short cg_niblk; /* number of inode blocks this cg */ 237 long cg_ndblk; /* number of data blocks this cg */ 238 struct csum cg_cs; /* cylinder summary information */ 239 long cg_rotor; /* position of last used block */ 240 long cg_frotor; /* position of last used frag */ 241 long cg_irotor; /* position of last used inode */ 242 long cg_frsum[MAXFRAG]; /* counts of available frags */ 243 long cg_btotoff; /* (long) block totals per cylinder */ 244 long cg_boff; /* (short) free block positions */ 245 long cg_iusedoff; /* (char) used inode map */ 246 long cg_freeoff; /* (u_char) free block map */ 247 long cg_nextfreeoff; /* (u_char) next available space */ 248 long cg_sparecon[16]; /* reserved for future use */ 249 u_char cg_space[1]; /* space for cylinder group maps */ 250 /* actually longer */ 251 }; 252 /* 253 * Macros for access to cylinder group array structures 254 */ 255 #define cg_blktot(cgp) \ 256 (((cgp)->cg_magic != CG_MAGIC) \ 257 ? (((struct ocg *)(cgp))->cg_btot) \ 258 : ((long *)((char *)(cgp) + (cgp)->cg_btotoff))) 259 #define cg_blks(fs, cgp, cylno) \ 260 (((cgp)->cg_magic != CG_MAGIC) \ 261 ? (((struct ocg *)(cgp))->cg_b[cylno]) \ 262 : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos)) 263 #define cg_inosused(cgp) \ 264 (((cgp)->cg_magic != CG_MAGIC) \ 265 ? (((struct ocg *)(cgp))->cg_iused) \ 266 : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff))) 267 #define cg_blksfree(cgp) \ 268 (((cgp)->cg_magic != CG_MAGIC) \ 269 ? (((struct ocg *)(cgp))->cg_free) \ 270 : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff))) 271 #define cg_chkmagic(cgp) \ 272 ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC) 273 274 /* 275 * The following structure is defined 276 * for compatibility with old file systems. 277 */ 278 struct ocg { 279 struct ocg *cg_link; /* linked list of cyl groups */ 280 struct ocg *cg_rlink; /* used for incore cyl groups */ 281 time_t cg_time; /* time last written */ 282 long cg_cgx; /* we are the cgx'th cylinder group */ 283 short cg_ncyl; /* number of cyl's this cg */ 284 short cg_niblk; /* number of inode blocks this cg */ 285 long cg_ndblk; /* number of data blocks this cg */ 286 struct csum cg_cs; /* cylinder summary information */ 287 long cg_rotor; /* position of last used block */ 288 long cg_frotor; /* position of last used frag */ 289 long cg_irotor; /* position of last used inode */ 290 long cg_frsum[8]; /* counts of available frags */ 291 long cg_btot[32]; /* block totals per cylinder */ 292 short cg_b[32][8]; /* positions of free blocks */ 293 char cg_iused[256]; /* used inode map */ 294 long cg_magic; /* magic number */ 295 u_char cg_free[1]; /* free block map */ 296 /* actually longer */ 297 }; 298 299 /* 300 * Turn file system block numbers into disk block addresses. 301 * This maps file system blocks to device size blocks. 302 */ 303 #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb) 304 #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb) 305 306 /* 307 * Cylinder group macros to locate things in cylinder groups. 308 * They calc file system addresses of cylinder group data structures. 309 */ 310 #define cgbase(fs, c) ((daddr_t)((fs)->fs_fpg * (c))) 311 #define cgstart(fs, c) \ 312 (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask))) 313 #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */ 314 #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */ 315 #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */ 316 #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */ 317 318 /* 319 * Macros for handling inode numbers: 320 * inode number to file system block offset. 321 * inode number to cylinder group number. 322 * inode number to file system block address. 323 */ 324 #define itoo(fs, x) ((x) % INOPB(fs)) 325 #define itog(fs, x) ((x) / (fs)->fs_ipg) 326 #define itod(fs, x) \ 327 ((daddr_t)(cgimin(fs, itog(fs, x)) + \ 328 (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs)))))) 329 330 /* 331 * Give cylinder group number for a file system block. 332 * Give cylinder group block number for a file system block. 333 */ 334 #define dtog(fs, d) ((d) / (fs)->fs_fpg) 335 #define dtogd(fs, d) ((d) % (fs)->fs_fpg) 336 337 /* 338 * Extract the bits for a block from a map. 339 * Compute the cylinder and rotational position of a cyl block addr. 340 */ 341 #define blkmap(fs, map, loc) \ 342 (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag))) 343 #define cbtocylno(fs, bno) \ 344 ((bno) * NSPF(fs) / (fs)->fs_spc) 345 #define cbtorpos(fs, bno) \ 346 (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \ 347 (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \ 348 (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect) 349 350 /* 351 * The following macros optimize certain frequently calculated 352 * quantities by using shifts and masks in place of divisions 353 * modulos and multiplications. 354 */ 355 #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \ 356 ((loc) & (fs)->fs_qbmask) 357 #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \ 358 ((loc) & (fs)->fs_qfmask) 359 #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \ 360 ((blk) << (fs)->fs_bshift) 361 #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \ 362 ((loc) >> (fs)->fs_bshift) 363 #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \ 364 ((loc) >> (fs)->fs_fshift) 365 #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \ 366 (((size) + (fs)->fs_qbmask) & (fs)->fs_bmask) 367 #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \ 368 (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) 369 #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \ 370 ((frags) >> (fs)->fs_fragshift) 371 #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \ 372 ((blks) << (fs)->fs_fragshift) 373 #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \ 374 ((fsb) & ((fs)->fs_frag - 1)) 375 #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \ 376 ((fsb) &~ ((fs)->fs_frag - 1)) 377 378 /* 379 * Determine the number of available frags given a 380 * percentage to hold in reserve 381 */ 382 #define freespace(fs, percentreserved) \ 383 (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \ 384 (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100)) 385 386 /* 387 * Determining the size of a file block in the file system. 388 */ 389 #define blksize(fs, ip, lbn) \ 390 (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \ 391 ? (fs)->fs_bsize \ 392 : (fragroundup(fs, blkoff(fs, (ip)->i_size)))) 393 #define dblksize(fs, dip, lbn) \ 394 (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \ 395 ? (fs)->fs_bsize \ 396 : (fragroundup(fs, blkoff(fs, (dip)->di_size)))) 397 398 /* 399 * Number of disk sectors per block; assumes DEV_BSIZE byte sector size. 400 */ 401 #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift) 402 #define NSPF(fs) ((fs)->fs_nspf) 403 404 /* 405 * INOPB is the number of inodes in a secondary storage block. 406 */ 407 #define INOPB(fs) ((fs)->fs_inopb) 408 #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift) 409 410 /* 411 * NINDIR is the number of indirects in a file system block. 412 */ 413 #define NINDIR(fs) ((fs)->fs_nindir) 414 415 extern int inside[], around[]; 416 extern u_char *fragtbl[]; 417