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1.1 root 1: /*
2: * Mach Operating System
3: * Copyright (c) 1991,1990 Carnegie Mellon University
4: * All Rights Reserved.
5: *
6: * Permission to use, copy, modify and distribute this software and its
7: * documentation is hereby granted, provided that both the copyright
8: * notice and this permission notice appear in all copies of the
9: * software, derivative works or modified versions, and any portions
10: * thereof, and that both notices appear in supporting documentation.
11: *
12: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
13: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
14: * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
15: *
16: * Carnegie Mellon requests users of this software to return to
17: *
18: * Software Distribution Coordinator or [email protected]
19: * School of Computer Science
20: * Carnegie Mellon University
21: * Pittsburgh PA 15213-3890
22: *
23: * any improvements or extensions that they make and grant Carnegie Mellon
24: * the rights to redistribute these changes.
25: */
26: /*
27: * Copyright (c) 1982, 1986 Regents of the University of California.
28: * All rights reserved.
29: *
30: * Redistribution and use in source and binary forms are permitted
31: * provided that the above copyright notice and this paragraph are
32: * duplicated in all such forms and that any documentation,
33: * advertising materials, and other materials related to such
34: * distribution and use acknowledge that the software was developed
35: * by the University of California, Berkeley. The name of the
36: * University may not be used to endorse or promote products derived
37: * from this software without specific prior written permission.
38: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
39: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
40: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
41: *
42: * @(#)fs.h 7.7 (Berkeley) 5/9/89
43: */
44:
45: /*
46: * Each disk drive contains some number of file systems.
47: * A file system consists of a number of cylinder groups.
48: * Each cylinder group has inodes and data.
49: *
50: * A file system is described by its super-block, which in turn
51: * describes the cylinder groups. The super-block is critical
52: * data and is replicated in each cylinder group to protect against
53: * catastrophic loss. This is done at `newfs' time and the critical
54: * super-block data does not change, so the copies need not be
55: * referenced further unless disaster strikes.
56: *
57: * For file system fs, the offsets of the various blocks of interest
58: * are given in the super block as:
59: * [fs->fs_sblkno] Super-block
60: * [fs->fs_cblkno] Cylinder group block
61: * [fs->fs_iblkno] Inode blocks
62: * [fs->fs_dblkno] Data blocks
63: * The beginning of cylinder group cg in fs, is given by
64: * the ``cgbase(fs, cg)'' macro.
65: *
66: * The first boot and super blocks are given in absolute disk addresses.
67: * The byte-offset forms are preferred, as they don't imply a sector size.
68: */
69: #define BBSIZE 8192
70: #define SBSIZE 8192
71: #define BBOFF ((mach_off_t)(0))
72: #define SBOFF ((mach_off_t)(BBOFF + BBSIZE))
73: #define BBLOCK ((mach_daddr_t)(0))
74: #define SBLOCK ((mach_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
75:
76: /*
77: * Addresses stored in inodes are capable of addressing fragments
78: * of `blocks'. File system blocks of at most size MAXBSIZE can
79: * be optionally broken into 2, 4, or 8 pieces, each of which is
80: * addressible; these pieces may be DEV_BSIZE, or some multiple of
81: * a DEV_BSIZE unit.
82: *
83: * Large files consist of exclusively large data blocks. To avoid
84: * undue wasted disk space, the last data block of a small file may be
85: * allocated as only as many fragments of a large block as are
86: * necessary. The file system format retains only a single pointer
87: * to such a fragment, which is a piece of a single large block that
88: * has been divided. The size of such a fragment is determinable from
89: * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
90: *
91: * The file system records space availability at the fragment level;
92: * to determine block availability, aligned fragments are examined.
93: *
94: * The root inode is the root of the file system.
95: * Inode 0 can't be used for normal purposes and
96: * historically bad blocks were linked to inode 1,
97: * thus the root inode is 2. (inode 1 is no longer used for
98: * this purpose, however numerous dump tapes make this
99: * assumption, so we are stuck with it)
100: */
101: #define ROOTINO ((mach_ino_t)2) /* i number of all roots */
102:
103: /*
104: * MINBSIZE is the smallest allowable block size.
105: * In order to insure that it is possible to create files of size
106: * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
107: * MINBSIZE must be big enough to hold a cylinder group block,
108: * thus changes to (struct cg) must keep its size within MINBSIZE.
109: * Note that super blocks are always of size SBSIZE,
110: * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
111: */
112: #define MINBSIZE 4096
113:
114: /*
115: * The path name on which the file system is mounted is maintained
116: * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
117: * the super block for this name.
118: * The limit on the amount of summary information per file system
119: * is defined by MAXCSBUFS. It is currently parameterized for a
120: * maximum of two million cylinders.
121: */
122: #define MAXMNTLEN 512
123: #define MAXCSBUFS 32
124:
125: /*
126: * Per cylinder group information; summarized in blocks allocated
127: * from first cylinder group data blocks. These blocks have to be
128: * read in from fs_csaddr (size fs_cssize) in addition to the
129: * super block.
130: *
131: * N.B. sizeof(struct csum) must be a power of two in order for
132: * the ``fs_cs'' macro to work (see below).
133: */
134: struct csum
135: {
136: int cs_ndir; /* number of directories */
137: int cs_nbfree; /* number of free blocks */
138: int cs_nifree; /* number of free inodes */
139: int cs_nffree; /* number of free frags */
140: };
141:
142: /*
143: * Super block for a file system.
144: */
145: #define FS_MAGIC 0x011954
146: struct fs
147: {
148: int xxx1; /* struct fs *fs_link; */
149: int xxx2; /* struct fs *fs_rlink; */
150: mach_daddr_t fs_sblkno; /* addr of super-block in filesys */
151: mach_daddr_t fs_cblkno; /* offset of cyl-block in filesys */
152: mach_daddr_t fs_iblkno; /* offset of inode-blocks in filesys */
153: mach_daddr_t fs_dblkno; /* offset of first data after cg */
154: int fs_cgoffset; /* cylinder group offset in cylinder */
155: int fs_cgmask; /* used to calc mod fs_ntrak */
156: mach_time_t fs_time; /* last time written */
157: int fs_size; /* number of blocks in fs */
158: int fs_dsize; /* number of data blocks in fs */
159: int fs_ncg; /* number of cylinder groups */
160: int fs_bsize; /* size of basic blocks in fs */
161: int fs_fsize; /* size of frag blocks in fs */
162: int fs_frag; /* number of frags in a block in fs */
163: /* these are configuration parameters */
164: int fs_minfree; /* minimum percentage of free blocks */
165: int fs_rotdelay; /* num of ms for optimal next block */
166: int fs_rps; /* disk revolutions per second */
167: /* these fields can be computed from the others */
168: int fs_bmask; /* ``blkoff'' calc of blk offsets */
169: int fs_fmask; /* ``fragoff'' calc of frag offsets */
170: int fs_bshift; /* ``lblkno'' calc of logical blkno */
171: int fs_fshift; /* ``numfrags'' calc number of frags */
172: /* these are configuration parameters */
173: int fs_maxcontig; /* max number of contiguous blks */
174: int fs_maxbpg; /* max number of blks per cyl group */
175: /* these fields can be computed from the others */
176: int fs_fragshift; /* block to frag shift */
177: int fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
178: int fs_sbsize; /* actual size of super block */
179: int fs_csmask; /* csum block offset */
180: int fs_csshift; /* csum block number */
181: int fs_nindir; /* value of NINDIR */
182: int fs_inopb; /* value of INOPB */
183: int fs_nspf; /* value of NSPF */
184: /* yet another configuration parameter */
185: int fs_optim; /* optimization preference, see below */
186: /* these fields are derived from the hardware */
187: int fs_npsect; /* # sectors/track including spares */
188: int fs_interleave; /* hardware sector interleave */
189: int fs_trackskew; /* sector 0 skew, per track */
190: int fs_headswitch; /* head switch time, usec */
191: int fs_trkseek; /* track-to-track seek, usec */
192: /* sizes determined by number of cylinder groups and their sizes */
193: mach_daddr_t fs_csaddr; /* blk addr of cyl grp summary area */
194: int fs_cssize; /* size of cyl grp summary area */
195: int fs_cgsize; /* cylinder group size */
196: /* these fields are derived from the hardware */
197: int fs_ntrak; /* tracks per cylinder */
198: int fs_nsect; /* sectors per track */
199: int fs_spc; /* sectors per cylinder */
200: /* this comes from the disk driver partitioning */
201: int fs_ncyl; /* cylinders in file system */
202: /* these fields can be computed from the others */
203: int fs_cpg; /* cylinders per group */
204: int fs_ipg; /* inodes per group */
205: int fs_fpg; /* blocks per group * fs_frag */
206: /* this data must be re-computed after crashes */
207: struct csum fs_cstotal; /* cylinder summary information */
208: /* these fields are cleared at mount time */
209: char fs_fmod; /* super block modified flag */
210: char fs_clean; /* file system is clean flag */
211: char fs_ronly; /* mounted read-only flag */
212: char fs_flags; /* currently unused flag */
213: char fs_fsmnt[MAXMNTLEN]; /* name mounted on */
214: /* these fields retain the current block allocation info */
215: int fs_cgrotor; /* last cg searched */
216: #if 1
217: int was_fs_csp[MAXCSBUFS];
218: #else
219: struct csum *fs_csp[MAXCSBUFS]; /* list of fs_cs info buffers */
220: #endif
221: int fs_cpc; /* cyl per cycle in postbl */
222: short fs_opostbl[16][8]; /* old rotation block list head */
223: long fs_sparecon[50]; /* reserved for future constants */
224: long fs_contigsumsize; /* size of cluster summary array */
225: long fs_maxsymlinklen; /* max length of an internal symlink */
226: long fs_inodefmt; /* format of on-disk inodes */
227: quad fs_maxfilesize; /* maximum representable file size */
228: quad fs_qbmask; /* ~fs_bmask - for use with quad size */
229: quad fs_qfmask; /* ~fs_fmask - for use with quad size */
230: long fs_state; /* validate fs_clean field */
231: int fs_postblformat; /* format of positional layout tables */
232: int fs_nrpos; /* number of rotaional positions */
233: int fs_postbloff; /* (short) rotation block list head */
234: int fs_rotbloff; /* (char) blocks for each rotation */
235: int fs_magic; /* magic number */
236: unsigned char fs_space[1]; /* list of blocks for each rotation */
237: /* actually longer */
238: };
239: /*
240: * Preference for optimization.
241: */
242: #define FS_OPTTIME 0 /* minimize allocation time */
243: #define FS_OPTSPACE 1 /* minimize disk fragmentation */
244:
245: /*
246: * Rotational layout table format types
247: */
248: #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */
249: #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */
250: /*
251: * Macros for access to superblock array structures
252: */
253: #define fs_postbl(fs, cylno) \
254: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
255: ? ((fs)->fs_opostbl[cylno]) \
256: : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
257: #define fs_rotbl(fs) \
258: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
259: ? ((fs)->fs_space) \
260: : ((unsigned char *)((char *)(fs) + (fs)->fs_rotbloff)))
261:
262: /*
263: * Convert cylinder group to base address of its global summary info.
264: *
265: * N.B. This macro assumes that sizeof(struct csum) is a power of two.
266: */
267: #define fs_cs(fs, indx) \
268: fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]
269:
270: /*
271: * Cylinder group block for a file system.
272: */
273: #define CG_MAGIC 0x090255
274: struct cg
275: {
276: int xxx1; /* struct cg *cg_link; */
277: int cg_magic; /* magic number */
278: mach_time_t cg_time; /* time last written */
279: int cg_cgx; /* we are the cgx'th cylinder group */
280: short cg_ncyl; /* number of cyl's this cg */
281: short cg_niblk; /* number of inode blocks this cg */
282: int cg_ndblk; /* number of data blocks this cg */
283: struct csum cg_cs; /* cylinder summary information */
284: int cg_rotor; /* position of last used block */
285: int cg_frotor; /* position of last used frag */
286: int cg_irotor; /* position of last used inode */
287: int cg_frsum[MAXFRAG]; /* counts of available frags */
288: int cg_btotoff; /* (long) block totals per cylinder */
289: int cg_boff; /* (short) free block positions */
290: int cg_iusedoff; /* (char) used inode map */
291: int cg_freeoff; /* (char) free block map */
292: int cg_nextfreeoff; /* (char) next available space */
293: int cg_sparecon[16]; /* reserved for future use */
294: unsigned char cg_space[1]; /* space for cylinder group maps */
295: /* actually longer */
296: };
297: /*
298: * Macros for access to cylinder group array structures
299: */
300: #define cg_blktot(cgp) \
301: (((cgp)->cg_magic != CG_MAGIC) \
302: ? (((struct ocg *)(cgp))->cg_btot) \
303: : ((int *)((char *)(cgp) + (cgp)->cg_btotoff)))
304: #define cg_blks(fs, cgp, cylno) \
305: (((cgp)->cg_magic != CG_MAGIC) \
306: ? (((struct ocg *)(cgp))->cg_b[cylno]) \
307: : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
308: #define cg_inosused(cgp) \
309: (((cgp)->cg_magic != CG_MAGIC) \
310: ? (((struct ocg *)(cgp))->cg_iused) \
311: : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
312: #define cg_blksfree(cgp) \
313: (((cgp)->cg_magic != CG_MAGIC) \
314: ? (((struct ocg *)(cgp))->cg_free) \
315: : ((unsigned char *)((char *)(cgp) + (cgp)->cg_freeoff)))
316: #define cg_chkmagic(cgp) \
317: ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
318:
319: /*
320: * The following structure is defined
321: * for compatibility with old file systems.
322: */
323: struct ocg
324: {
325: int xxx1; /* struct ocg *cg_link; */
326: int xxx2; /* struct ocg *cg_rlink; */
327: mach_time_t cg_time; /* time last written */
328: int cg_cgx; /* we are the cgx'th cylinder group */
329: short cg_ncyl; /* number of cyl's this cg */
330: short cg_niblk; /* number of inode blocks this cg */
331: int cg_ndblk; /* number of data blocks this cg */
332: struct csum cg_cs; /* cylinder summary information */
333: int cg_rotor; /* position of last used block */
334: int cg_frotor; /* position of last used frag */
335: int cg_irotor; /* position of last used inode */
336: int cg_frsum[8]; /* counts of available frags */
337: int cg_btot[32]; /* block totals per cylinder */
338: short cg_b[32][8]; /* positions of free blocks */
339: char cg_iused[256]; /* used inode map */
340: int cg_magic; /* magic number */
341: unsigned char cg_free[1]; /* free block map */
342: /* actually longer */
343: };
344:
345: /*
346: * Turn file system block numbers into disk block addresses.
347: * This maps file system blocks to device size blocks.
348: */
349: #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb)
350: #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb)
351:
352: /*
353: * Cylinder group macros to locate things in cylinder groups.
354: * They calc file system addresses of cylinder group data structures.
355: */
356: #define cgbase(fs, c) ((mach_daddr_t)((fs)->fs_fpg * (c)))
357: #define cgstart(fs, c) \
358: (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
359: #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */
360: #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */
361: #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */
362: #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */
363:
364: /*
365: * Macros for handling inode numbers:
366: * inode number to file system block offset.
367: * inode number to cylinder group number.
368: * inode number to file system block address.
369: */
370: #define itoo(fs, x) ((x) % INOPB(fs))
371: #define itog(fs, x) ((x) / (fs)->fs_ipg)
372: #define itod(fs, x) \
373: ((mach_daddr_t)(cgimin(fs, itog(fs, x)) + \
374: (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
375:
376: /*
377: * Give cylinder group number for a file system block.
378: * Give cylinder group block number for a file system block.
379: */
380: #define dtog(fs, d) ((d) / (fs)->fs_fpg)
381: #define dtogd(fs, d) ((d) % (fs)->fs_fpg)
382:
383: /*
384: * Extract the bits for a block from a map.
385: * Compute the cylinder and rotational position of a cyl block addr.
386: */
387: #define blkmap(fs, map, loc) \
388: (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
389: #define cbtocylno(fs, bno) \
390: ((bno) * NSPF(fs) / (fs)->fs_spc)
391: #define cbtorpos(fs, bno) \
392: (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
393: (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
394: (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
395:
396: /*
397: * The following macros optimize certain frequently calculated
398: * quantities by using shifts and masks in place of divisions
399: * modulos and multiplications.
400: */
401: #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
402: ((loc) & ~(fs)->fs_bmask)
403: #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \
404: ((loc) & ~(fs)->fs_fmask)
405: #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
406: ((loc) >> (fs)->fs_bshift)
407: #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
408: ((loc) >> (fs)->fs_fshift)
409: #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \
410: (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
411: #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
412: (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
413: #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \
414: ((frags) >> (fs)->fs_fragshift)
415: #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \
416: ((blks) << (fs)->fs_fragshift)
417: #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \
418: ((fsb) & ((fs)->fs_frag - 1))
419: #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \
420: ((fsb) &~ ((fs)->fs_frag - 1))
421:
422: /*
423: * Determine the number of available frags given a
424: * percentage to hold in reserve
425: */
426: #define freespace(fs, percentreserved) \
427: (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
428: (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
429:
430: /*
431: * Determining the size of a file block in the file system.
432: */
433: #define blksize(fs, ip, lbn) \
434: (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
435: ? (fs)->fs_bsize \
436: : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
437: #define dblksize(fs, dip, lbn) \
438: (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
439: ? (fs)->fs_bsize \
440: : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
441:
442: /*
443: * Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
444: */
445: #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift)
446: #define NSPF(fs) ((fs)->fs_nspf)
447:
448: /*
449: * INOPB is the number of inodes in a secondary storage block.
450: */
451: #define INOPB(fs) ((fs)->fs_inopb)
452: #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift)
453:
454: /*
455: * NINDIR is the number of indirects in a file system block.
456: */
457: #define NINDIR(fs) ((fs)->fs_nindir)
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.