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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 is only permitted until one year after the first shipment
6: * of 4.4BSD by the Regents. Otherwise, redistribution and use in source and
7: * binary forms are permitted provided that: (1) source distributions retain
8: * this entire copyright notice and comment, and (2) distributions including
9: * binaries display the following acknowledgement: This product includes
10: * software developed by the University of California, Berkeley and its
11: * contributors'' in the documentation or other materials provided with the
12: * distribution and in all advertising materials mentioning features or use
13: * of this software. Neither the name of the University nor the names of
14: * its contributors may be used to endorse or promote products derived from
15: * this software without specific prior written permission.
16: * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
17: * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
18: * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19: *
20: * @(#)fs.h 7.10 (Berkeley) 6/28/90
21: */
22:
23: /*
24: * Each disk drive contains some number of file systems.
25: * A file system consists of a number of cylinder groups.
26: * Each cylinder group has inodes and data.
27: *
28: * A file system is described by its super-block, which in turn
29: * describes the cylinder groups. The super-block is critical
30: * data and is replicated in each cylinder group to protect against
31: * catastrophic loss. This is done at `newfs' time and the critical
32: * super-block data does not change, so the copies need not be
33: * referenced further unless disaster strikes.
34: *
35: * For file system fs, the offsets of the various blocks of interest
36: * are given in the super block as:
37: * [fs->fs_sblkno] Super-block
38: * [fs->fs_cblkno] Cylinder group block
39: * [fs->fs_iblkno] Inode blocks
40: * [fs->fs_dblkno] Data blocks
41: * The beginning of cylinder group cg in fs, is given by
42: * the ``cgbase(fs, cg)'' macro.
43: *
44: * The first boot and super blocks are given in absolute disk addresses.
45: * The byte-offset forms are preferred, as they don't imply a sector size.
46: */
47: #define BBSIZE 8192
48: #define SBSIZE 8192
49: #define BBOFF ((off_t)(0))
50: #define SBOFF ((off_t)(BBOFF + BBSIZE))
51: #define BBLOCK ((daddr_t)(0))
52: #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
53:
54: /*
55: * Addresses stored in inodes are capable of addressing fragments
56: * of `blocks'. File system blocks of at most size MAXBSIZE can
57: * be optionally broken into 2, 4, or 8 pieces, each of which is
58: * addressible; these pieces may be DEV_BSIZE, or some multiple of
59: * a DEV_BSIZE unit.
60: *
61: * Large files consist of exclusively large data blocks. To avoid
62: * undue wasted disk space, the last data block of a small file may be
63: * allocated as only as many fragments of a large block as are
64: * necessary. The file system format retains only a single pointer
65: * to such a fragment, which is a piece of a single large block that
66: * has been divided. The size of such a fragment is determinable from
67: * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
68: *
69: * The file system records space availability at the fragment level;
70: * to determine block availability, aligned fragments are examined.
71: *
72: * The root inode is the root of the file system.
73: * Inode 0 can't be used for normal purposes and
74: * historically bad blocks were linked to inode 1,
75: * thus the root inode is 2. (inode 1 is no longer used for
76: * this purpose, however numerous dump tapes make this
77: * assumption, so we are stuck with it)
78: */
79: #define ROOTINO ((ino_t)2) /* i number of all roots */
80:
81: /*
82: * MINBSIZE is the smallest allowable block size.
83: * In order to insure that it is possible to create files of size
84: * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
85: * MINBSIZE must be big enough to hold a cylinder group block,
86: * thus changes to (struct cg) must keep its size within MINBSIZE.
87: * Note that super blocks are always of size SBSIZE,
88: * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
89: */
90: #define MINBSIZE 4096
91:
92: /*
93: * The path name on which the file system is mounted is maintained
94: * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
95: * the super block for this name.
96: * The limit on the amount of summary information per file system
97: * is defined by MAXCSBUFS. It is currently parameterized for a
98: * maximum of two million cylinders.
99: */
100: #define MAXMNTLEN 512
101: #define MAXCSBUFS 32
102:
103: /*
104: * Per cylinder group information; summarized in blocks allocated
105: * from first cylinder group data blocks. These blocks have to be
106: * read in from fs_csaddr (size fs_cssize) in addition to the
107: * super block.
108: *
109: * N.B. sizeof(struct csum) must be a power of two in order for
110: * the ``fs_cs'' macro to work (see below).
111: */
112: struct csum {
113: long cs_ndir; /* number of directories */
114: long cs_nbfree; /* number of free blocks */
115: long cs_nifree; /* number of free inodes */
116: long cs_nffree; /* number of free frags */
117: };
118:
119: /*
120: * Super block for a file system.
121: */
122: #define FS_MAGIC 0x011954
123: #define FSOKAY 0x7c269d38
124: struct fs
125: {
126: struct fs *fs_link; /* linked list of file systems */
127: struct fs *fs_rlink; /* used for incore super blocks */
128: daddr_t fs_sblkno; /* addr of super-block in filesys */
129: daddr_t fs_cblkno; /* offset of cyl-block in filesys */
130: daddr_t fs_iblkno; /* offset of inode-blocks in filesys */
131: daddr_t fs_dblkno; /* offset of first data after cg */
132: long fs_cgoffset; /* cylinder group offset in cylinder */
133: long fs_cgmask; /* used to calc mod fs_ntrak */
134: time_t fs_time; /* last time written */
135: long fs_size; /* number of blocks in fs */
136: long fs_dsize; /* number of data blocks in fs */
137: long fs_ncg; /* number of cylinder groups */
138: long fs_bsize; /* size of basic blocks in fs */
139: long fs_fsize; /* size of frag blocks in fs */
140: long fs_frag; /* number of frags in a block in fs */
141: /* these are configuration parameters */
142: long fs_minfree; /* minimum percentage of free blocks */
143: long fs_rotdelay; /* num of ms for optimal next block */
144: long fs_rps; /* disk revolutions per second */
145: /* these fields can be computed from the others */
146: long fs_bmask; /* ``blkoff'' calc of blk offsets */
147: long fs_fmask; /* ``fragoff'' calc of frag offsets */
148: long fs_bshift; /* ``lblkno'' calc of logical blkno */
149: long fs_fshift; /* ``numfrags'' calc number of frags */
150: /* these are configuration parameters */
151: long fs_maxcontig; /* max number of contiguous blks */
152: long fs_maxbpg; /* max number of blks per cyl group */
153: /* these fields can be computed from the others */
154: long fs_fragshift; /* block to frag shift */
155: long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
156: long fs_sbsize; /* actual size of super block */
157: long fs_csmask; /* csum block offset */
158: long fs_csshift; /* csum block number */
159: long fs_nindir; /* value of NINDIR */
160: long fs_inopb; /* value of INOPB */
161: long fs_nspf; /* value of NSPF */
162: /* yet another configuration parameter */
163: long fs_optim; /* optimization preference, see below */
164: /* these fields are derived from the hardware */
165: long fs_npsect; /* # sectors/track including spares */
166: long fs_interleave; /* hardware sector interleave */
167: long fs_trackskew; /* sector 0 skew, per track */
168: long fs_headswitch; /* head switch time, usec */
169: long fs_trkseek; /* track-to-track seek, usec */
170: /* sizes determined by number of cylinder groups and their sizes */
171: daddr_t fs_csaddr; /* blk addr of cyl grp summary area */
172: long fs_cssize; /* size of cyl grp summary area */
173: long fs_cgsize; /* cylinder group size */
174: /* these fields are derived from the hardware */
175: long fs_ntrak; /* tracks per cylinder */
176: long fs_nsect; /* sectors per track */
177: long fs_spc; /* sectors per cylinder */
178: /* this comes from the disk driver partitioning */
179: long fs_ncyl; /* cylinders in file system */
180: /* these fields can be computed from the others */
181: long fs_cpg; /* cylinders per group */
182: long fs_ipg; /* inodes per group */
183: long fs_fpg; /* blocks per group * fs_frag */
184: /* this data must be re-computed after crashes */
185: struct csum fs_cstotal; /* cylinder summary information */
186: /* these fields are cleared at mount time */
187: char fs_fmod; /* super block modified flag */
188: char fs_clean; /* file system is clean flag */
189: char fs_ronly; /* mounted read-only flag */
190: char fs_flags; /* currently unused flag */
191: char fs_fsmnt[MAXMNTLEN]; /* name mounted on */
192: /* these fields retain the current block allocation info */
193: long fs_cgrotor; /* last cg searched */
194: struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */
195: long fs_cpc; /* cyl per cycle in postbl */
196: short fs_opostbl[16][8]; /* old rotation block list head */
197: long fs_sparecon[55]; /* reserved for future constants */
198: long fs_state; /* validate fs_clean field */
199: quad fs_qbmask; /* ~fs_bmask - for use with quad size */
200: quad fs_qfmask; /* ~fs_fmask - for use with quad size */
201: long fs_postblformat; /* format of positional layout tables */
202: long fs_nrpos; /* number of rotaional positions */
203: long fs_postbloff; /* (short) rotation block list head */
204: long fs_rotbloff; /* (u_char) blocks for each rotation */
205: long fs_magic; /* magic number */
206: u_char fs_space[1]; /* list of blocks for each rotation */
207: /* actually longer */
208: };
209: /*
210: * Preference for optimization.
211: */
212: #define FS_OPTTIME 0 /* minimize allocation time */
213: #define FS_OPTSPACE 1 /* minimize disk fragmentation */
214:
215: /*
216: * Rotational layout table format types
217: */
218: #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */
219: #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */
220: /*
221: * Macros for access to superblock array structures
222: */
223: #define fs_postbl(fs, cylno) \
224: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
225: ? ((fs)->fs_opostbl[cylno]) \
226: : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
227: #define fs_rotbl(fs) \
228: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
229: ? ((fs)->fs_space) \
230: : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff)))
231:
232: /*
233: * Convert cylinder group to base address of its global summary info.
234: *
235: * N.B. This macro assumes that sizeof(struct csum) is a power of two.
236: */
237: #define fs_cs(fs, indx) \
238: fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]
239:
240: /*
241: * Cylinder group block for a file system.
242: */
243: #define CG_MAGIC 0x090255
244: struct cg {
245: struct cg *cg_link; /* linked list of cyl groups */
246: long cg_magic; /* magic number */
247: time_t cg_time; /* time last written */
248: long cg_cgx; /* we are the cgx'th cylinder group */
249: short cg_ncyl; /* number of cyl's this cg */
250: short cg_niblk; /* number of inode blocks this cg */
251: long cg_ndblk; /* number of data blocks this cg */
252: struct csum cg_cs; /* cylinder summary information */
253: long cg_rotor; /* position of last used block */
254: long cg_frotor; /* position of last used frag */
255: long cg_irotor; /* position of last used inode */
256: long cg_frsum[MAXFRAG]; /* counts of available frags */
257: long cg_btotoff; /* (long) block totals per cylinder */
258: long cg_boff; /* (short) free block positions */
259: long cg_iusedoff; /* (char) used inode map */
260: long cg_freeoff; /* (u_char) free block map */
261: long cg_nextfreeoff; /* (u_char) next available space */
262: long cg_sparecon[16]; /* reserved for future use */
263: u_char cg_space[1]; /* space for cylinder group maps */
264: /* actually longer */
265: };
266: /*
267: * Macros for access to cylinder group array structures
268: */
269: #define cg_blktot(cgp) \
270: (((cgp)->cg_magic != CG_MAGIC) \
271: ? (((struct ocg *)(cgp))->cg_btot) \
272: : ((long *)((char *)(cgp) + (cgp)->cg_btotoff)))
273: #define cg_blks(fs, cgp, cylno) \
274: (((cgp)->cg_magic != CG_MAGIC) \
275: ? (((struct ocg *)(cgp))->cg_b[cylno]) \
276: : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
277: #define cg_inosused(cgp) \
278: (((cgp)->cg_magic != CG_MAGIC) \
279: ? (((struct ocg *)(cgp))->cg_iused) \
280: : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
281: #define cg_blksfree(cgp) \
282: (((cgp)->cg_magic != CG_MAGIC) \
283: ? (((struct ocg *)(cgp))->cg_free) \
284: : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff)))
285: #define cg_chkmagic(cgp) \
286: ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
287:
288: /*
289: * The following structure is defined
290: * for compatibility with old file systems.
291: */
292: struct ocg {
293: struct ocg *cg_link; /* linked list of cyl groups */
294: struct ocg *cg_rlink; /* used for incore cyl groups */
295: time_t cg_time; /* time last written */
296: long cg_cgx; /* we are the cgx'th cylinder group */
297: short cg_ncyl; /* number of cyl's this cg */
298: short cg_niblk; /* number of inode blocks this cg */
299: long cg_ndblk; /* number of data blocks this cg */
300: struct csum cg_cs; /* cylinder summary information */
301: long cg_rotor; /* position of last used block */
302: long cg_frotor; /* position of last used frag */
303: long cg_irotor; /* position of last used inode */
304: long cg_frsum[8]; /* counts of available frags */
305: long cg_btot[32]; /* block totals per cylinder */
306: short cg_b[32][8]; /* positions of free blocks */
307: char cg_iused[256]; /* used inode map */
308: long cg_magic; /* magic number */
309: u_char cg_free[1]; /* free block map */
310: /* actually longer */
311: };
312:
313: /*
314: * Turn file system block numbers into disk block addresses.
315: * This maps file system blocks to device size blocks.
316: */
317: #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb)
318: #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb)
319:
320: /*
321: * Cylinder group macros to locate things in cylinder groups.
322: * They calc file system addresses of cylinder group data structures.
323: */
324: #define cgbase(fs, c) ((daddr_t)((fs)->fs_fpg * (c)))
325: #define cgstart(fs, c) \
326: (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
327: #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */
328: #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */
329: #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */
330: #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */
331:
332: /*
333: * Macros for handling inode numbers:
334: * inode number to file system block offset.
335: * inode number to cylinder group number.
336: * inode number to file system block address.
337: */
338: #define itoo(fs, x) ((x) % INOPB(fs))
339: #define itog(fs, x) ((x) / (fs)->fs_ipg)
340: #define itod(fs, x) \
341: ((daddr_t)(cgimin(fs, itog(fs, x)) + \
342: (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
343:
344: /*
345: * Give cylinder group number for a file system block.
346: * Give cylinder group block number for a file system block.
347: */
348: #define dtog(fs, d) ((d) / (fs)->fs_fpg)
349: #define dtogd(fs, d) ((d) % (fs)->fs_fpg)
350:
351: /*
352: * Extract the bits for a block from a map.
353: * Compute the cylinder and rotational position of a cyl block addr.
354: */
355: #define blkmap(fs, map, loc) \
356: (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
357: #define cbtocylno(fs, bno) \
358: ((bno) * NSPF(fs) / (fs)->fs_spc)
359: #define cbtorpos(fs, bno) \
360: (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
361: (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
362: (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
363:
364: /*
365: * The following macros optimize certain frequently calculated
366: * quantities by using shifts and masks in place of divisions
367: * modulos and multiplications.
368: */
369: #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
370: ((loc) & ~(fs)->fs_bmask)
371: #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \
372: ((loc) & ~(fs)->fs_fmask)
373: #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
374: ((blk) << (fs)->fs_bshift)
375: #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
376: ((loc) >> (fs)->fs_bshift)
377: #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
378: ((loc) >> (fs)->fs_fshift)
379: #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \
380: (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
381: #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
382: (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
383: #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \
384: ((frags) >> (fs)->fs_fragshift)
385: #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \
386: ((blks) << (fs)->fs_fragshift)
387: #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \
388: ((fsb) & ((fs)->fs_frag - 1))
389: #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \
390: ((fsb) &~ ((fs)->fs_frag - 1))
391:
392: /*
393: * Determine the number of available frags given a
394: * percentage to hold in reserve
395: */
396: #define freespace(fs, percentreserved) \
397: (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
398: (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
399:
400: /*
401: * Determining the size of a file block in the file system.
402: */
403: #define blksize(fs, ip, lbn) \
404: (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
405: ? (fs)->fs_bsize \
406: : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
407: #define dblksize(fs, dip, lbn) \
408: (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
409: ? (fs)->fs_bsize \
410: : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
411:
412: /*
413: * Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
414: */
415: #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift)
416: #define NSPF(fs) ((fs)->fs_nspf)
417:
418: /*
419: * INOPB is the number of inodes in a secondary storage block.
420: */
421: #define INOPB(fs) ((fs)->fs_inopb)
422: #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift)
423:
424: /*
425: * NINDIR is the number of indirects in a file system block.
426: */
427: #define NINDIR(fs) ((fs)->fs_nindir)
428:
429: #ifdef KERNEL
430: struct fs *getfs();
431: #endif
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