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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, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. All advertising materials mentioning features or use of this software
14: * must display the following acknowledgement:
15: * This product includes software developed by the University of
16: * California, Berkeley and its contributors.
17: * 4. Neither the name of the University nor the names of its contributors
18: * may be used to endorse or promote products derived from this software
19: * without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31: * SUCH DAMAGE.
32: *
33: * @(#)fs.h 7.12 (Berkeley) 5/8/91
34: */
35:
36: /*
37: * Each disk drive contains some number of file systems.
38: * A file system consists of a number of cylinder groups.
39: * Each cylinder group has inodes and data.
40: *
41: * A file system is described by its super-block, which in turn
42: * describes the cylinder groups. The super-block is critical
43: * data and is replicated in each cylinder group to protect against
44: * catastrophic loss. This is done at `newfs' time and the critical
45: * super-block data does not change, so the copies need not be
46: * referenced further unless disaster strikes.
47: *
48: * For file system fs, the offsets of the various blocks of interest
49: * are given in the super block as:
50: * [fs->fs_sblkno] Super-block
51: * [fs->fs_cblkno] Cylinder group block
52: * [fs->fs_iblkno] Inode blocks
53: * [fs->fs_dblkno] Data blocks
54: * The beginning of cylinder group cg in fs, is given by
55: * the ``cgbase(fs, cg)'' macro.
56: *
57: * The first boot and super blocks are given in absolute disk addresses.
58: * The byte-offset forms are preferred, as they don't imply a sector size.
59: */
60: #define BBSIZE 8192
61: #define SBSIZE 8192
62: #define BBOFF ((off_t)(0))
63: #define SBOFF ((off_t)(BBOFF + BBSIZE))
64: #define BBLOCK ((daddr_t)(0))
65: #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
66:
67: /*
68: * Addresses stored in inodes are capable of addressing fragments
69: * of `blocks'. File system blocks of at most size MAXBSIZE can
70: * be optionally broken into 2, 4, or 8 pieces, each of which is
71: * addressible; these pieces may be DEV_BSIZE, or some multiple of
72: * a DEV_BSIZE unit.
73: *
74: * Large files consist of exclusively large data blocks. To avoid
75: * undue wasted disk space, the last data block of a small file may be
76: * allocated as only as many fragments of a large block as are
77: * necessary. The file system format retains only a single pointer
78: * to such a fragment, which is a piece of a single large block that
79: * has been divided. The size of such a fragment is determinable from
80: * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
81: *
82: * The file system records space availability at the fragment level;
83: * to determine block availability, aligned fragments are examined.
84: *
85: * The root inode is the root of the file system.
86: * Inode 0 can't be used for normal purposes and
87: * historically bad blocks were linked to inode 1,
88: * thus the root inode is 2. (inode 1 is no longer used for
89: * this purpose, however numerous dump tapes make this
90: * assumption, so we are stuck with it)
91: */
92: #define ROOTINO ((ino_t)2)
93:
94: /*
95: * MINBSIZE is the smallest allowable block size.
96: * In order to insure that it is possible to create files of size
97: * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
98: * MINBSIZE must be big enough to hold a cylinder group block,
99: * thus changes to (struct cg) must keep its size within MINBSIZE.
100: * Note that super blocks are always of size SBSIZE,
101: * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
102: */
103: #define MINBSIZE 4096
104:
105: /*
106: * The path name on which the file system is mounted is maintained
107: * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
108: * the super block for this name.
109: * The limit on the amount of summary information per file system
110: * is defined by MAXCSBUFS. It is currently parameterized for a
111: * maximum of two million cylinders.
112: */
113: #define MAXMNTLEN 512
114: #define MAXCSBUFS 32
115:
116: /*
117: * Per cylinder group information; summarized in blocks allocated
118: * from first cylinder group data blocks. These blocks have to be
119: * read in from fs_csaddr (size fs_cssize) in addition to the
120: * super block.
121: *
122: * N.B. sizeof(struct csum) must be a power of two in order for
123: * the ``fs_cs'' macro to work (see below).
124: */
125: struct csum {
126: long cs_ndir; /* number of directories */
127: long cs_nbfree; /* number of free blocks */
128: long cs_nifree; /* number of free inodes */
129: long cs_nffree; /* number of free frags */
130: };
131:
132: /*
133: * Super block for a file system.
134: */
135: #define FS_MAGIC 0x011954
136: #define FSOKAY 0x7c269d38
137: struct fs
138: {
139: struct fs *fs_link; /* linked list of file systems */
140: struct fs *fs_rlink; /* used for incore super blocks */
141: daddr_t fs_sblkno; /* addr of super-block in filesys */
142: daddr_t fs_cblkno; /* offset of cyl-block in filesys */
143: daddr_t fs_iblkno; /* offset of inode-blocks in filesys */
144: daddr_t fs_dblkno; /* offset of first data after cg */
145: long fs_cgoffset; /* cylinder group offset in cylinder */
146: long fs_cgmask; /* used to calc mod fs_ntrak */
147: time_t fs_time; /* last time written */
148: long fs_size; /* number of blocks in fs */
149: long fs_dsize; /* number of data blocks in fs */
150: long fs_ncg; /* number of cylinder groups */
151: long fs_bsize; /* size of basic blocks in fs */
152: long fs_fsize; /* size of frag blocks in fs */
153: long fs_frag; /* number of frags in a block in fs */
154: /* these are configuration parameters */
155: long fs_minfree; /* minimum percentage of free blocks */
156: long fs_rotdelay; /* num of ms for optimal next block */
157: long fs_rps; /* disk revolutions per second */
158: /* these fields can be computed from the others */
159: long fs_bmask; /* ``blkoff'' calc of blk offsets */
160: long fs_fmask; /* ``fragoff'' calc of frag offsets */
161: long fs_bshift; /* ``lblkno'' calc of logical blkno */
162: long fs_fshift; /* ``numfrags'' calc number of frags */
163: /* these are configuration parameters */
164: long fs_maxcontig; /* max number of contiguous blks */
165: long fs_maxbpg; /* max number of blks per cyl group */
166: /* these fields can be computed from the others */
167: long fs_fragshift; /* block to frag shift */
168: long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
169: long fs_sbsize; /* actual size of super block */
170: long fs_csmask; /* csum block offset */
171: long fs_csshift; /* csum block number */
172: long fs_nindir; /* value of NINDIR */
173: long fs_inopb; /* value of INOPB */
174: long fs_nspf; /* value of NSPF */
175: /* yet another configuration parameter */
176: long fs_optim; /* optimization preference, see below */
177: /* these fields are derived from the hardware */
178: long fs_npsect; /* # sectors/track including spares */
179: long fs_interleave; /* hardware sector interleave */
180: long fs_trackskew; /* sector 0 skew, per track */
181: long fs_headswitch; /* head switch time, usec */
182: long fs_trkseek; /* track-to-track seek, usec */
183: /* sizes determined by number of cylinder groups and their sizes */
184: daddr_t fs_csaddr; /* blk addr of cyl grp summary area */
185: long fs_cssize; /* size of cyl grp summary area */
186: long fs_cgsize; /* cylinder group size */
187: /* these fields are derived from the hardware */
188: long fs_ntrak; /* tracks per cylinder */
189: long fs_nsect; /* sectors per track */
190: long fs_spc; /* sectors per cylinder */
191: /* this comes from the disk driver partitioning */
192: long fs_ncyl; /* cylinders in file system */
193: /* these fields can be computed from the others */
194: long fs_cpg; /* cylinders per group */
195: long fs_ipg; /* inodes per group */
196: long fs_fpg; /* blocks per group * fs_frag */
197: /* this data must be re-computed after crashes */
198: struct csum fs_cstotal; /* cylinder summary information */
199: /* these fields are cleared at mount time */
200: char fs_fmod; /* super block modified flag */
201: char fs_clean; /* file system is clean flag */
202: char fs_ronly; /* mounted read-only flag */
203: char fs_flags; /* currently unused flag */
204: char fs_fsmnt[MAXMNTLEN]; /* name mounted on */
205: /* these fields retain the current block allocation info */
206: long fs_cgrotor; /* last cg searched */
207: struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */
208: long fs_cpc; /* cyl per cycle in postbl */
209: short fs_opostbl[16][8]; /* old rotation block list head */
210: long fs_sparecon[55]; /* reserved for future constants */
211: long fs_state; /* validate fs_clean field */
212: quad fs_qbmask; /* ~fs_bmask - for use with quad size */
213: quad fs_qfmask; /* ~fs_fmask - for use with quad size */
214: long fs_postblformat; /* format of positional layout tables */
215: long fs_nrpos; /* number of rotaional positions */
216: long fs_postbloff; /* (short) rotation block list head */
217: long fs_rotbloff; /* (u_char) blocks for each rotation */
218: long fs_magic; /* magic number */
219: u_char fs_space[1]; /* list of blocks for each rotation */
220: /* actually longer */
221: };
222: /*
223: * Preference for optimization.
224: */
225: #define FS_OPTTIME 0 /* minimize allocation time */
226: #define FS_OPTSPACE 1 /* minimize disk fragmentation */
227:
228: /*
229: * Rotational layout table format types
230: */
231: #define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */
232: #define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */
233: /*
234: * Macros for access to superblock array structures
235: */
236: #define fs_postbl(fs, cylno) \
237: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
238: ? ((fs)->fs_opostbl[cylno]) \
239: : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
240: #define fs_rotbl(fs) \
241: (((fs)->fs_postblformat == FS_42POSTBLFMT) \
242: ? ((fs)->fs_space) \
243: : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff)))
244:
245: /*
246: * Convert cylinder group to base address of its global summary info.
247: *
248: * N.B. This macro assumes that sizeof(struct csum) is a power of two.
249: */
250: #define fs_cs(fs, indx) \
251: fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]
252:
253: /*
254: * Cylinder group block for a file system.
255: */
256: #define CG_MAGIC 0x090255
257: struct cg {
258: struct cg *cg_link; /* linked list of cyl groups */
259: long cg_magic; /* magic number */
260: time_t cg_time; /* time last written */
261: long cg_cgx; /* we are the cgx'th cylinder group */
262: short cg_ncyl; /* number of cyl's this cg */
263: short cg_niblk; /* number of inode blocks this cg */
264: long cg_ndblk; /* number of data blocks this cg */
265: struct csum cg_cs; /* cylinder summary information */
266: long cg_rotor; /* position of last used block */
267: long cg_frotor; /* position of last used frag */
268: long cg_irotor; /* position of last used inode */
269: long cg_frsum[MAXFRAG]; /* counts of available frags */
270: long cg_btotoff; /* (long) block totals per cylinder */
271: long cg_boff; /* (short) free block positions */
272: long cg_iusedoff; /* (char) used inode map */
273: long cg_freeoff; /* (u_char) free block map */
274: long cg_nextfreeoff; /* (u_char) next available space */
275: long cg_sparecon[16]; /* reserved for future use */
276: u_char cg_space[1]; /* space for cylinder group maps */
277: /* actually longer */
278: };
279: /*
280: * Macros for access to cylinder group array structures
281: */
282: #define cg_blktot(cgp) \
283: (((cgp)->cg_magic != CG_MAGIC) \
284: ? (((struct ocg *)(cgp))->cg_btot) \
285: : ((long *)((char *)(cgp) + (cgp)->cg_btotoff)))
286: #define cg_blks(fs, cgp, cylno) \
287: (((cgp)->cg_magic != CG_MAGIC) \
288: ? (((struct ocg *)(cgp))->cg_b[cylno]) \
289: : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
290: #define cg_inosused(cgp) \
291: (((cgp)->cg_magic != CG_MAGIC) \
292: ? (((struct ocg *)(cgp))->cg_iused) \
293: : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
294: #define cg_blksfree(cgp) \
295: (((cgp)->cg_magic != CG_MAGIC) \
296: ? (((struct ocg *)(cgp))->cg_free) \
297: : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff)))
298: #define cg_chkmagic(cgp) \
299: ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
300:
301: /*
302: * The following structure is defined
303: * for compatibility with old file systems.
304: */
305: struct ocg {
306: struct ocg *cg_link; /* linked list of cyl groups */
307: struct ocg *cg_rlink; /* used for incore cyl groups */
308: time_t cg_time; /* time last written */
309: long cg_cgx; /* we are the cgx'th cylinder group */
310: short cg_ncyl; /* number of cyl's this cg */
311: short cg_niblk; /* number of inode blocks this cg */
312: long cg_ndblk; /* number of data blocks this cg */
313: struct csum cg_cs; /* cylinder summary information */
314: long cg_rotor; /* position of last used block */
315: long cg_frotor; /* position of last used frag */
316: long cg_irotor; /* position of last used inode */
317: long cg_frsum[8]; /* counts of available frags */
318: long cg_btot[32]; /* block totals per cylinder */
319: short cg_b[32][8]; /* positions of free blocks */
320: char cg_iused[256]; /* used inode map */
321: long cg_magic; /* magic number */
322: u_char cg_free[1]; /* free block map */
323: /* actually longer */
324: };
325:
326: /*
327: * Turn file system block numbers into disk block addresses.
328: * This maps file system blocks to device size blocks.
329: */
330: #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb)
331: #define dbtofsb(fs, b) ((b) >> (fs)->fs_fsbtodb)
332:
333: /*
334: * Cylinder group macros to locate things in cylinder groups.
335: * They calc file system addresses of cylinder group data structures.
336: */
337: #define cgbase(fs, c) ((daddr_t)((fs)->fs_fpg * (c)))
338: #define cgstart(fs, c) \
339: (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
340: #define cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno) /* super blk */
341: #define cgtod(fs, c) (cgstart(fs, c) + (fs)->fs_cblkno) /* cg block */
342: #define cgimin(fs, c) (cgstart(fs, c) + (fs)->fs_iblkno) /* inode blk */
343: #define cgdmin(fs, c) (cgstart(fs, c) + (fs)->fs_dblkno) /* 1st data */
344:
345: /*
346: * Macros for handling inode numbers:
347: * inode number to file system block offset.
348: * inode number to cylinder group number.
349: * inode number to file system block address.
350: */
351: #define itoo(fs, x) ((x) % INOPB(fs))
352: #define itog(fs, x) ((x) / (fs)->fs_ipg)
353: #define itod(fs, x) \
354: ((daddr_t)(cgimin(fs, itog(fs, x)) + \
355: (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
356:
357: /*
358: * Give cylinder group number for a file system block.
359: * Give cylinder group block number for a file system block.
360: */
361: #define dtog(fs, d) ((d) / (fs)->fs_fpg)
362: #define dtogd(fs, d) ((d) % (fs)->fs_fpg)
363:
364: /*
365: * Extract the bits for a block from a map.
366: * Compute the cylinder and rotational position of a cyl block addr.
367: */
368: #define blkmap(fs, map, loc) \
369: (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
370: #define cbtocylno(fs, bno) \
371: ((bno) * NSPF(fs) / (fs)->fs_spc)
372: #define cbtorpos(fs, bno) \
373: (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
374: (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
375: (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
376:
377: /*
378: * The following macros optimize certain frequently calculated
379: * quantities by using shifts and masks in place of divisions
380: * modulos and multiplications.
381: */
382: #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
383: ((loc) & ~(fs)->fs_bmask)
384: #define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \
385: ((loc) & ~(fs)->fs_fmask)
386: #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
387: ((blk) << (fs)->fs_bshift)
388: #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
389: ((loc) >> (fs)->fs_bshift)
390: #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
391: ((loc) >> (fs)->fs_fshift)
392: #define blkroundup(fs, size) /* calculates roundup(size, fs->fs_bsize) */ \
393: (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
394: #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
395: (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
396: #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \
397: ((frags) >> (fs)->fs_fragshift)
398: #define blkstofrags(fs, blks) /* calculates (blks * fs->fs_frag) */ \
399: ((blks) << (fs)->fs_fragshift)
400: #define fragnum(fs, fsb) /* calculates (fsb % fs->fs_frag) */ \
401: ((fsb) & ((fs)->fs_frag - 1))
402: #define blknum(fs, fsb) /* calculates rounddown(fsb, fs->fs_frag) */ \
403: ((fsb) &~ ((fs)->fs_frag - 1))
404:
405: /*
406: * Determine the number of available frags given a
407: * percentage to hold in reserve
408: */
409: #define freespace(fs, percentreserved) \
410: (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
411: (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
412:
413: /*
414: * Determining the size of a file block in the file system.
415: */
416: #define blksize(fs, ip, lbn) \
417: (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
418: ? (fs)->fs_bsize \
419: : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
420: #define dblksize(fs, dip, lbn) \
421: (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
422: ? (fs)->fs_bsize \
423: : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
424:
425: /*
426: * Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
427: */
428: #define NSPB(fs) ((fs)->fs_nspf << (fs)->fs_fragshift)
429: #define NSPF(fs) ((fs)->fs_nspf)
430:
431: /*
432: * INOPB is the number of inodes in a secondary storage block.
433: */
434: #define INOPB(fs) ((fs)->fs_inopb)
435: #define INOPF(fs) ((fs)->fs_inopb >> (fs)->fs_fragshift)
436:
437: /*
438: * NINDIR is the number of indirects in a file system block.
439: */
440: #define NINDIR(fs) ((fs)->fs_nindir)
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