1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)fs.h 7.11 (Berkeley) 10/24/90 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 * The root inode is the root of the file system. 60 * Inode 0 can't be used for normal purposes and 61 * historically bad blocks were linked to inode 1, 62 * thus the root inode is 2. (inode 1 is no longer used for 63 * this purpose, however numerous dump tapes make this 64 * assumption, so we are stuck with it) 65 */ 66 #define ROOTINO ((ino_t)2) /* i number of all roots */ 67 68 /* 69 * MINBSIZE is the smallest allowable block size. 70 * In order to insure that it is possible to create files of size 71 * 2^32 with only two levels of indirection, MINBSIZE is set to 4096. 72 * MINBSIZE must be big enough to hold a cylinder group block, 73 * thus changes to (struct cg) must keep its size within MINBSIZE. 74 * Note that super blocks are always of size SBSIZE, 75 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE. 76 */ 77 #define MINBSIZE 4096 78 79 /* 80 * The path name on which the file system is mounted is maintained 81 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 82 * the super block for this name. 83 * The limit on the amount of summary information per file system 84 * is defined by MAXCSBUFS. It is currently parameterized for a 85 * maximum of two million cylinders. 86 */ 87 #define MAXMNTLEN 512 88 #define MAXCSBUFS 32 89 90 /* 91 * Per cylinder group information; summarized in blocks allocated 92 * from first cylinder group data blocks. These blocks have to be 93 * read in from fs_csaddr (size fs_cssize) in addition to the 94 * super block. 95 * 96 * N.B. sizeof(struct csum) must be a power of two in order for 97 * the ``fs_cs'' macro to work (see below). 98 */ 99 struct csum { 100 long cs_ndir; /* number of directories */ 101 long cs_nbfree; /* number of free blocks */ 102 long cs_nifree; /* number of free inodes */ 103 long cs_nffree; /* number of free frags */ 104 }; 105 106 /* 107 * Super block for a file system. 108 */ 109 #define FS_MAGIC 0x011954 110 #define FSOKAY 0x7c269d38 111 struct fs 112 { 113 struct fs *fs_link; /* linked list of file systems */ 114 struct fs *fs_rlink; /* used for incore super blocks */ 115 daddr_t fs_sblkno; /* addr of super-block in filesys */ 116 daddr_t fs_cblkno; /* offset of cyl-block in filesys */ 117 daddr_t fs_iblkno; /* offset of inode-blocks in filesys */ 118 daddr_t fs_dblkno; /* offset of first data after cg */ 119 long fs_cgoffset; /* cylinder group offset in cylinder */ 120 long fs_cgmask; /* used to calc mod fs_ntrak */ 121 time_t fs_time; /* last time written */ 122 long fs_size; /* number of blocks in fs */ 123 long fs_dsize; /* number of data blocks in fs */ 124 long fs_ncg; /* number of cylinder groups */ 125 long fs_bsize; /* size of basic blocks in fs */ 126 long fs_fsize; /* size of frag blocks in fs */ 127 long fs_frag; /* number of frags in a block in fs */ 128 /* these are configuration parameters */ 129 long fs_minfree; /* minimum percentage of free blocks */ 130 long fs_rotdelay; /* num of ms for optimal next block */ 131 long fs_rps; /* disk revolutions per second */ 132 /* these fields can be computed from the others */ 133 long fs_bmask; /* ``blkoff'' calc of blk offsets */ 134 long fs_fmask; /* ``fragoff'' calc of frag offsets */ 135 long fs_bshift; /* ``lblkno'' calc of logical blkno */ 136 long fs_fshift; /* ``numfrags'' calc number of frags */ 137 /* these are configuration parameters */ 138 long fs_maxcontig; /* max number of contiguous blks */ 139 long fs_maxbpg; /* max number of blks per cyl group */ 140 /* these fields can be computed from the others */ 141 long fs_fragshift; /* block to frag shift */ 142 long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ 143 long fs_sbsize; /* actual size of super block */ 144 long fs_csmask; /* csum block offset */ 145 long fs_csshift; /* csum block number */ 146 long fs_nindir; /* value of NINDIR */ 147 long fs_inopb; /* value of INOPB */ 148 long fs_nspf; /* value of NSPF */ 149 /* yet another configuration parameter */ 150 long fs_optim; /* optimization preference, see below */ 151 /* these fields are derived from the hardware */ 152 long fs_npsect; /* # sectors/track including spares */ 153 long fs_interleave; /* hardware sector interleave */ 154 long fs_trackskew; /* sector 0 skew, per track */ 155 long fs_headswitch; /* head switch time, usec */ 156 long fs_trkseek; /* track-to-track seek, usec */ 157 /* sizes determined by number of cylinder groups and their sizes */ 158 daddr_t fs_csaddr; /* blk addr of cyl grp summary area */ 159 long fs_cssize; /* size of cyl grp summary area */ 160 long fs_cgsize; /* cylinder group size */ 161 /* these fields are derived from the hardware */ 162 long fs_ntrak; /* tracks per cylinder */ 163 long fs_nsect; /* sectors per track */ 164 long fs_spc; /* sectors per cylinder */ 165 /* this comes from the disk driver partitioning */ 166 long fs_ncyl; /* cylinders in file system */ 167 /* these fields can be computed from the others */ 168 long fs_cpg; /* cylinders per group */ 169 long fs_ipg; /* inodes per group */ 170 long fs_fpg; /* blocks per group * fs_frag */ 171 /* this data must be re-computed after crashes */ 172 struct csum fs_cstotal; /* cylinder summary information */ 173 /* these fields are cleared at mount time */ 174 char fs_fmod; /* super block modified flag */ 175 char fs_clean; /* file system is clean flag */ 176 char fs_ronly; /* mounted read-only flag */ 177 char fs_flags; /* currently unused flag */ 178 char fs_fsmnt[MAXMNTLEN]; /* name mounted on */ 179 /* these fields retain the current block allocation info */ 180 long fs_cgrotor; /* last cg searched */ 181 struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */ 182 long fs_cpc; /* cyl per cycle in postbl */ 183 short fs_opostbl[16][8]; /* old rotation block list head */ 184 long fs_sparecon[55]; /* reserved for future constants */ 185 long fs_state; /* validate fs_clean field */ 186 quad fs_qbmask; /* ~fs_bmask - for use with quad size */ 187 quad fs_qfmask; /* ~fs_fmask - for use with quad size */ 188 long fs_postblformat; /* format of positional layout tables */ 189 long fs_nrpos; /* number of rotaional positions */ 190 long fs_postbloff; /* (short) rotation block list head */ 191 long fs_rotbloff; /* (u_char) blocks for each rotation */ 192 long fs_magic; /* magic number */ 193 u_char fs_space[1]; /* list of blocks for each rotation */ 194 /* actually longer */ 195 }; 196 /* 197 * Preference for optimization. 198 */ 199 #define FS_OPTTIME 0 /* minimize allocation time */ 200 #define FS_OPTSPACE 1 /* minimize disk fragmentation */ 201 202 /* 203 * Rotational layout table format types 204 */ 205 #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */ 206 #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */ 207 /* 208 * Macros for access to superblock array structures 209 */ 210 #define fs_postbl(fs, cylno) \ 211 (((fs)->fs_postblformat == FS_42POSTBLFMT) \ 212 ? ((fs)->fs_opostbl[cylno]) \ 213 : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos)) 214 #define fs_rotbl(fs) \ 215 (((fs)->fs_postblformat == FS_42POSTBLFMT) \ 216 ? ((fs)->fs_space) \ 217 : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff))) 218 219 /* 220 * Convert cylinder group to base address of its global summary info. 221 * 222 * N.B. This macro assumes that sizeof(struct csum) is a power of two. 223 */ 224 #define fs_cs(fs, indx) \ 225 fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask] 226 227 /* 228 * Cylinder group block for a file system. 229 */ 230 #define CG_MAGIC 0x090255 231 struct cg { 232 struct cg *cg_link; /* linked list of cyl groups */ 233 long cg_magic; /* magic number */ 234 time_t cg_time; /* time last written */ 235 long cg_cgx; /* we are the cgx'th cylinder group */ 236 short cg_ncyl; /* number of cyl's this cg */ 237 short cg_niblk; /* number of inode blocks this cg */ 238 long cg_ndblk; /* number of data blocks this cg */ 239 struct csum cg_cs; /* cylinder summary information */ 240 long cg_rotor; /* position of last used block */ 241 long cg_frotor; /* position of last used frag */ 242 long cg_irotor; /* position of last used inode */ 243 long cg_frsum[MAXFRAG]; /* counts of available frags */ 244 long cg_btotoff; /* (long) block totals per cylinder */ 245 long cg_boff; /* (short) free block positions */ 246 long cg_iusedoff; /* (char) used inode map */ 247 long cg_freeoff; /* (u_char) free block map */ 248 long cg_nextfreeoff; /* (u_char) next available space */ 249 long cg_sparecon[16]; /* reserved for future use */ 250 u_char cg_space[1]; /* space for cylinder group maps */ 251 /* actually longer */ 252 }; 253 /* 254 * Macros for access to cylinder group array structures 255 */ 256 #define cg_blktot(cgp) \ 257 (((cgp)->cg_magic != CG_MAGIC) \ 258 ? (((struct ocg *)(cgp))->cg_btot) \ 259 : ((long *)((char *)(cgp) + (cgp)->cg_btotoff))) 260 #define cg_blks(fs, cgp, cylno) \ 261 (((cgp)->cg_magic != CG_MAGIC) \ 262 ? (((struct ocg *)(cgp))->cg_b[cylno]) \ 263 : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos)) 264 #define cg_inosused(cgp) \ 265 (((cgp)->cg_magic != CG_MAGIC) \ 266 ? (((struct ocg *)(cgp))->cg_iused) \ 267 : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff))) 268 #define cg_blksfree(cgp) \ 269 (((cgp)->cg_magic != CG_MAGIC) \ 270 ? (((struct ocg *)(cgp))->cg_free) \ 271 : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff))) 272 #define cg_chkmagic(cgp) \ 273 ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC) 274 275 /* 276 * The following structure is defined 277 * for compatibility with old file systems. 278 */ 279 struct ocg { 280 struct ocg *cg_link; /* linked list of cyl groups */ 281 struct ocg *cg_rlink; /* used for incore cyl groups */ 282 time_t cg_time; /* time last written */ 283 long cg_cgx; /* we are the cgx'th cylinder group */ 284 short cg_ncyl; /* number of cyl's this cg */ 285 short cg_niblk; /* number of inode blocks this cg */ 286 long cg_ndblk; /* number of data blocks this cg */ 287 struct csum cg_cs; /* cylinder summary information */ 288 long cg_rotor; /* position of last used block */ 289 long cg_frotor; /* position of last used frag */ 290 long cg_irotor; /* position of last used inode */ 291 long cg_frsum[8]; /* counts of available frags */ 292 long cg_btot[32]; /* block totals per cylinder */ 293 short cg_b[32][8]; /* positions of free blocks */ 294 char cg_iused[256]; /* used inode map */ 295 long cg_magic; /* magic number */ 296 u_char cg_free[1]; /* free block map */ 297 /* actually longer */ 298 }; 299 300 /* 301 * Turn file system block numbers into disk block addresses. 302 * This maps file system blocks to device size blocks. 303 */ 304 #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb) 305 #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb) 306 307 /* 308 * Cylinder group macros to locate things in cylinder groups. 309 * They calc file system addresses of cylinder group data structures. 310 */ 311 #define cgbase(fs, c) ((daddr_t)((fs)->fs_fpg * (c))) 312 #define cgstart(fs, c) \ 313 (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask))) 314 #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */ 315 #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */ 316 #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */ 317 #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */ 318 319 /* 320 * Macros for handling inode numbers: 321 * inode number to file system block offset. 322 * inode number to cylinder group number. 323 * inode number to file system block address. 324 */ 325 #define itoo(fs, x) ((x) % INOPB(fs)) 326 #define itog(fs, x) ((x) / (fs)->fs_ipg) 327 #define itod(fs, x) \ 328 ((daddr_t)(cgimin(fs, itog(fs, x)) + \ 329 (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs)))))) 330 331 /* 332 * Give cylinder group number for a file system block. 333 * Give cylinder group block number for a file system block. 334 */ 335 #define dtog(fs, d) ((d) / (fs)->fs_fpg) 336 #define dtogd(fs, d) ((d) % (fs)->fs_fpg) 337 338 /* 339 * Extract the bits for a block from a map. 340 * Compute the cylinder and rotational position of a cyl block addr. 341 */ 342 #define blkmap(fs, map, loc) \ 343 (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag))) 344 #define cbtocylno(fs, bno) \ 345 ((bno) * NSPF(fs) / (fs)->fs_spc) 346 #define cbtorpos(fs, bno) \ 347 (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \ 348 (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \ 349 (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect) 350 351 /* 352 * The following macros optimize certain frequently calculated 353 * quantities by using shifts and masks in place of divisions 354 * modulos and multiplications. 355 */ 356 #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \ 357 ((loc) & ~(fs)->fs_bmask) 358 #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \ 359 ((loc) & ~(fs)->fs_fmask) 360 #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \ 361 ((blk) << (fs)->fs_bshift) 362 #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \ 363 ((loc) >> (fs)->fs_bshift) 364 #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \ 365 ((loc) >> (fs)->fs_fshift) 366 #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \ 367 (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask) 368 #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \ 369 (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask) 370 #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \ 371 ((frags) >> (fs)->fs_fragshift) 372 #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \ 373 ((blks) << (fs)->fs_fragshift) 374 #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \ 375 ((fsb) & ((fs)->fs_frag - 1)) 376 #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \ 377 ((fsb) &~ ((fs)->fs_frag - 1)) 378 379 /* 380 * Determine the number of available frags given a 381 * percentage to hold in reserve 382 */ 383 #define freespace(fs, percentreserved) \ 384 (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \ 385 (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100)) 386 387 /* 388 * Determining the size of a file block in the file system. 389 */ 390 #define blksize(fs, ip, lbn) \ 391 (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \ 392 ? (fs)->fs_bsize \ 393 : (fragroundup(fs, blkoff(fs, (ip)->i_size)))) 394 #define dblksize(fs, dip, lbn) \ 395 (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \ 396 ? (fs)->fs_bsize \ 397 : (fragroundup(fs, blkoff(fs, (dip)->di_size)))) 398 399 /* 400 * Number of disk sectors per block; assumes DEV_BSIZE byte sector size. 401 */ 402 #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift) 403 #define NSPF(fs) ((fs)->fs_nspf) 404 405 /* 406 * INOPB is the number of inodes in a secondary storage block. 407 */ 408 #define INOPB(fs) ((fs)->fs_inopb) 409 #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift) 410 411 /* 412 * NINDIR is the number of indirects in a file system block. 413 */ 414 #define NINDIR(fs) ((fs)->fs_nindir) 415