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1.1 root 1: /*
2: * Copyright (c) 1982, 1986 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms are permitted
6: * provided that the above copyright notice and this paragraph are
7: * duplicated in all such forms and that any documentation,
8: * advertising materials, and other materials related to such
9: * distribution and use acknowledge that the software was developed
10: * by the University of California, Berkeley. The name of the
11: * University may not be used to endorse or promote products derived
12: * from this software without specific prior written permission.
13: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
15: * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16: *
17: * @(#)fs.h 7.6 (Berkeley) 6/27/88
18: */
19:
20: /*
21: * Each disk drive contains some number of file systems.
22: * A file system consists of a number of cylinder groups.
23: * Each cylinder group has inodes and data.
24: *
25: * A file system is described by its super-block, which in turn
26: * describes the cylinder groups. The super-block is critical
27: * data and is replicated in each cylinder group to protect against
28: * catastrophic loss. This is done at `newfs' time and the critical
29: * super-block data does not change, so the copies need not be
30: * referenced further unless disaster strikes.
31: *
32: * For file system fs, the offsets of the various blocks of interest
33: * are given in the super block as:
34: * [fs->fs_sblkno] Super-block
35: * [fs->fs_cblkno] Cylinder group block
36: * [fs->fs_iblkno] Inode blocks
37: * [fs->fs_dblkno] Data blocks
38: * The beginning of cylinder group cg in fs, is given by
39: * the ``cgbase(fs, cg)'' macro.
40: *
41: * The first boot and super blocks are given in absolute disk addresses.
42: * The byte-offset forms are preferred, as they don't imply a sector size.
43: */
44: #define BBSIZE 8192
45: #define SBSIZE 8192
46: #define BBOFF ((off_t)(0))
47: #define SBOFF ((off_t)(BBOFF + BBSIZE))
48: #define BBLOCK ((daddr_t)(0))
49: #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
50:
51: /*
52: * Addresses stored in inodes are capable of addressing fragments
53: * of `blocks'. File system blocks of at most size MAXBSIZE can
54: * be optionally broken into 2, 4, or 8 pieces, each of which is
55: * addressible; these pieces may be DEV_BSIZE, or some multiple of
56: * a DEV_BSIZE unit.
57: *
58: * Large files consist of exclusively large data blocks. To avoid
59: * undue wasted disk space, the last data block of a small file may be
60: * allocated as only as many fragments of a large block as are
61: * necessary. The file system format retains only a single pointer
62: * to such a fragment, which is a piece of a single large block that
63: * has been divided. The size of such a fragment is determinable from
64: * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
65: *
66: * The file system records space availability at the fragment level;
67: * to determine block availability, aligned fragments are examined.
68: *
69: * The root inode is the root of the file system.
70: * Inode 0 can't be used for normal purposes and
71: * historically bad blocks were linked to inode 1,
72: * thus the root inode is 2. (inode 1 is no longer used for
73: * this purpose, however numerous dump tapes make this
74: * assumption, so we are stuck with it)
75: */
76: #define ROOTINO ((ino_t)2) /* i number of all roots */
77:
78: /*
79: * MINBSIZE is the smallest allowable block size.
80: * In order to insure that it is possible to create files of size
81: * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
82: * MINBSIZE must be big enough to hold a cylinder group block,
83: * thus changes to (struct cg) must keep its size within MINBSIZE.
84: * Note that super blocks are always of size SBSIZE,
85: * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
86: */
87: #define MINBSIZE 4096
88:
89: /*
90: * The path name on which the file system is mounted is maintained
91: * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
92: * the super block for this name.
93: * The limit on the amount of summary information per file system
94: * is defined by MAXCSBUFS. It is currently parameterized for a
95: * maximum of two million cylinders.
96: */
97: #define MAXMNTLEN 512
98: #define MAXCSBUFS 32
99:
100: /*
101: * Per cylinder group information; summarized in blocks allocated
102: * from first cylinder group data blocks. These blocks have to be
103: * read in from fs_csaddr (size fs_cssize) in addition to the
104: * super block.
105: *
106: * N.B. sizeof(struct csum) must be a power of two in order for
107: * the ``fs_cs'' macro to work (see below).
108: */
109: struct csum {
110: long cs_ndir; /* number of directories */
111: long cs_nbfree; /* number of free blocks */
112: long cs_nifree; /* number of free inodes */
113: long cs_nffree; /* number of free frags */
114: };
115:
116: /*
117: * Super block for a file system.
118: */
119: #define FS_MAGIC 0x011954
120: struct fs
121: {
122: struct fs *fs_link; /* linked list of file systems */
123: struct fs *fs_rlink; /* used for incore super blocks */
124: daddr_t fs_sblkno; /* addr of super-block in filesys */
125: daddr_t fs_cblkno; /* offset of cyl-block in filesys */
126: daddr_t fs_iblkno; /* offset of inode-blocks in filesys */
127: daddr_t fs_dblkno; /* offset of first data after cg */
128: long fs_cgoffset; /* cylinder group offset in cylinder */
129: long fs_cgmask; /* used to calc mod fs_ntrak */
130: time_t fs_time; /* last time written */
131: long fs_size; /* number of blocks in fs */
132: long fs_dsize; /* number of data blocks in fs */
133: long fs_ncg; /* number of cylinder groups */
134: long fs_bsize; /* size of basic blocks in fs */
135: long fs_fsize; /* size of frag blocks in fs */
136: long fs_frag; /* number of frags in a block in fs */
137: /* these are configuration parameters */
138: long fs_minfree; /* minimum percentage of free blocks */
139: long fs_rotdelay; /* num of ms for optimal next block */
140: long fs_rps; /* disk revolutions per second */
141: /* these fields can be computed from the others */
142: long fs_bmask; /* ``blkoff'' calc of blk offsets */
143: long fs_fmask; /* ``fragoff'' calc of frag offsets */
144: long fs_bshift; /* ``lblkno'' calc of logical blkno */
145: long fs_fshift; /* ``numfrags'' calc number of frags */
146: /* these are configuration parameters */
147: long fs_maxcontig; /* max number of contiguous blks */
148: long fs_maxbpg; /* max number of blks per cyl group */
149: /* these fields can be computed from the others */
150: long fs_fragshift; /* block to frag shift */
151: long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
152: long fs_sbsize; /* actual size of super block */
153: long fs_csmask; /* csum block offset */
154: long fs_csshift; /* csum block number */
155: long fs_nindir; /* value of NINDIR */
156: long fs_inopb; /* value of INOPB */
157: long fs_nspf; /* value of NSPF */
158: /* yet another configuration parameter */
159: long fs_optim; /* optimization preference, see below */
160: /* these fields are derived from the hardware */
161: long fs_npsect; /* # sectors/track including spares */
162: long fs_interleave; /* hardware sector interleave */
163: long fs_trackskew; /* sector 0 skew, per track */
164: long fs_headswitch; /* head switch time, usec */
165: long fs_trkseek; /* track-to-track seek, usec */
166: /* sizes determined by number of cylinder groups and their sizes */
167: daddr_t fs_csaddr; /* blk addr of cyl grp summary area */
168: long fs_cssize; /* size of cyl grp summary area */
169: long fs_cgsize; /* cylinder group size */
170: /* these fields are derived from the hardware */
171: long fs_ntrak; /* tracks per cylinder */
172: long fs_nsect; /* sectors per track */
173: long fs_spc; /* sectors per cylinder */
174: /* this comes from the disk driver partitioning */
175: long fs_ncyl; /* cylinders in file system */
176: /* these fields can be computed from the others */
177: long fs_cpg; /* cylinders per group */
178: long fs_ipg; /* inodes per group */
179: long fs_fpg; /* blocks per group * fs_frag */
180: /* this data must be re-computed after crashes */
181: struct csum fs_cstotal; /* cylinder summary information */
182: /* these fields are cleared at mount time */
183: char fs_fmod; /* super block modified flag */
184: char fs_clean; /* file system is clean flag */
185: char fs_ronly; /* mounted read-only flag */
186: char fs_flags; /* currently unused flag */
187: char fs_fsmnt[MAXMNTLEN]; /* name mounted on */
188: /* these fields retain the current block allocation info */
189: long fs_cgrotor; /* last cg searched */
190: struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */
191: long fs_cpc; /* cyl per cycle in postbl */
192: short fs_opostbl[16][8]; /* old rotation block list head */
193: long fs_sparecon[56]; /* reserved for future constants */
194: quad fs_qbmask; /* ~fs_bmask - for use with quad size */
195: quad fs_qfmask; /* ~fs_fmask - for use with quad size */
196: long fs_postblformat; /* format of positional layout tables */
197: long fs_nrpos; /* number of rotaional positions */
198: long fs_postbloff; /* (short) rotation block list head */
199: long fs_rotbloff; /* (u_char) blocks for each rotation */
200: long fs_magic; /* magic number */
201: u_char fs_space[1]; /* list of blocks for each rotation */
202: /* actually longer */
203: };
204: /*
205: * Preference for optimization.
206: */
207: #define FS_OPTTIME 0 /* minimize allocation time */
208: #define FS_OPTSPACE 1 /* minimize disk fragmentation */
209:
210: /*
211: * Rotational layout table format types
212: */
213: #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */
214: #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */
215: /*
216: * Macros for access to superblock array structures
217: */
218: #define fs_postbl(fs, cylno) \
219: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
220: ? ((fs)->fs_opostbl[cylno]) \
221: : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
222: #define fs_rotbl(fs) \
223: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
224: ? ((fs)->fs_space) \
225: : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff)))
226:
227: /*
228: * Convert cylinder group to base address of its global summary info.
229: *
230: * N.B. This macro assumes that sizeof(struct csum) is a power of two.
231: */
232: #define fs_cs(fs, indx) \
233: fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]
234:
235: /*
236: * Cylinder group block for a file system.
237: */
238: #define CG_MAGIC 0x090255
239: struct cg {
240: struct cg *cg_link; /* linked list of cyl groups */
241: long cg_magic; /* magic number */
242: time_t cg_time; /* time last written */
243: long cg_cgx; /* we are the cgx'th cylinder group */
244: short cg_ncyl; /* number of cyl's this cg */
245: short cg_niblk; /* number of inode blocks this cg */
246: long cg_ndblk; /* number of data blocks this cg */
247: struct csum cg_cs; /* cylinder summary information */
248: long cg_rotor; /* position of last used block */
249: long cg_frotor; /* position of last used frag */
250: long cg_irotor; /* position of last used inode */
251: long cg_frsum[MAXFRAG]; /* counts of available frags */
252: long cg_btotoff; /* (long) block totals per cylinder */
253: long cg_boff; /* (short) free block positions */
254: long cg_iusedoff; /* (char) used inode map */
255: long cg_freeoff; /* (u_char) free block map */
256: long cg_nextfreeoff; /* (u_char) next available space */
257: long cg_sparecon[16]; /* reserved for future use */
258: u_char cg_space[1]; /* space for cylinder group maps */
259: /* actually longer */
260: };
261: /*
262: * Macros for access to cylinder group array structures
263: */
264: #define cg_blktot(cgp) \
265: (((cgp)->cg_magic != CG_MAGIC) \
266: ? (((struct ocg *)(cgp))->cg_btot) \
267: : ((long *)((char *)(cgp) + (cgp)->cg_btotoff)))
268: #define cg_blks(fs, cgp, cylno) \
269: (((cgp)->cg_magic != CG_MAGIC) \
270: ? (((struct ocg *)(cgp))->cg_b[cylno]) \
271: : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
272: #define cg_inosused(cgp) \
273: (((cgp)->cg_magic != CG_MAGIC) \
274: ? (((struct ocg *)(cgp))->cg_iused) \
275: : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
276: #define cg_blksfree(cgp) \
277: (((cgp)->cg_magic != CG_MAGIC) \
278: ? (((struct ocg *)(cgp))->cg_free) \
279: : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff)))
280: #define cg_chkmagic(cgp) \
281: ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
282:
283: /*
284: * The following structure is defined
285: * for compatibility with old file systems.
286: */
287: struct ocg {
288: struct ocg *cg_link; /* linked list of cyl groups */
289: struct ocg *cg_rlink; /* used for incore cyl groups */
290: time_t cg_time; /* time last written */
291: long cg_cgx; /* we are the cgx'th cylinder group */
292: short cg_ncyl; /* number of cyl's this cg */
293: short cg_niblk; /* number of inode blocks this cg */
294: long cg_ndblk; /* number of data blocks this cg */
295: struct csum cg_cs; /* cylinder summary information */
296: long cg_rotor; /* position of last used block */
297: long cg_frotor; /* position of last used frag */
298: long cg_irotor; /* position of last used inode */
299: long cg_frsum[8]; /* counts of available frags */
300: long cg_btot[32]; /* block totals per cylinder */
301: short cg_b[32][8]; /* positions of free blocks */
302: char cg_iused[256]; /* used inode map */
303: long cg_magic; /* magic number */
304: u_char cg_free[1]; /* free block map */
305: /* actually longer */
306: };
307:
308: /*
309: * Turn file system block numbers into disk block addresses.
310: * This maps file system blocks to device size blocks.
311: */
312: #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb)
313: #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb)
314:
315: /*
316: * Cylinder group macros to locate things in cylinder groups.
317: * They calc file system addresses of cylinder group data structures.
318: */
319: #define cgbase(fs, c) ((daddr_t)((fs)->fs_fpg * (c)))
320: #define cgstart(fs, c) \
321: (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
322: #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */
323: #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */
324: #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */
325: #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */
326:
327: /*
328: * Macros for handling inode numbers:
329: * inode number to file system block offset.
330: * inode number to cylinder group number.
331: * inode number to file system block address.
332: */
333: #define itoo(fs, x) ((x) % INOPB(fs))
334: #define itog(fs, x) ((x) / (fs)->fs_ipg)
335: #define itod(fs, x) \
336: ((daddr_t)(cgimin(fs, itog(fs, x)) + \
337: (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
338:
339: /*
340: * Give cylinder group number for a file system block.
341: * Give cylinder group block number for a file system block.
342: */
343: #define dtog(fs, d) ((d) / (fs)->fs_fpg)
344: #define dtogd(fs, d) ((d) % (fs)->fs_fpg)
345:
346: /*
347: * Extract the bits for a block from a map.
348: * Compute the cylinder and rotational position of a cyl block addr.
349: */
350: #define blkmap(fs, map, loc) \
351: (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
352: #define cbtocylno(fs, bno) \
353: ((bno) * NSPF(fs) / (fs)->fs_spc)
354: #define cbtorpos(fs, bno) \
355: (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
356: (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
357: (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
358:
359: /*
360: * The following macros optimize certain frequently calculated
361: * quantities by using shifts and masks in place of divisions
362: * modulos and multiplications.
363: */
364: #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
365: ((loc) & ~(fs)->fs_bmask)
366: #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \
367: ((loc) & ~(fs)->fs_fmask)
368: #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
369: ((loc) >> (fs)->fs_bshift)
370: #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
371: ((loc) >> (fs)->fs_fshift)
372: #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \
373: (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
374: #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
375: (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
376: #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \
377: ((frags) >> (fs)->fs_fragshift)
378: #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \
379: ((blks) << (fs)->fs_fragshift)
380: #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \
381: ((fsb) & ((fs)->fs_frag - 1))
382: #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \
383: ((fsb) &~ ((fs)->fs_frag - 1))
384:
385: /*
386: * Determine the number of available frags given a
387: * percentage to hold in reserve
388: */
389: #define freespace(fs, percentreserved) \
390: (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
391: (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
392:
393: /*
394: * Determining the size of a file block in the file system.
395: */
396: #define blksize(fs, ip, lbn) \
397: (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
398: ? (fs)->fs_bsize \
399: : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
400: #define dblksize(fs, dip, lbn) \
401: (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
402: ? (fs)->fs_bsize \
403: : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
404:
405: /*
406: * Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
407: */
408: #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift)
409: #define NSPF(fs) ((fs)->fs_nspf)
410:
411: /*
412: * INOPB is the number of inodes in a secondary storage block.
413: */
414: #define INOPB(fs) ((fs)->fs_inopb)
415: #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift)
416:
417: /*
418: * NINDIR is the number of indirects in a file system block.
419: */
420: #define NINDIR(fs) ((fs)->fs_nindir)
421:
422: #ifdef KERNEL
423: struct fs *getfs();
424: struct fs *mountfs();
425: #endif
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