xref: /freebsd/sys/ufs/ffs/fs.h (revision 41466b50c1d5bfd1cf6adaae547a579a75d7c04e)
1 /*
2  * Copyright (c) 1982, 1986, 1993
3  *	The Regents of the University of California.  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	8.13 (Berkeley) 3/21/95
34  * $FreeBSD$
35  */
36 
37 #ifndef _UFS_FFS_FS_H_
38 #define _UFS_FFS_FS_H_
39 
40 /*
41  * Each disk drive contains some number of file systems.
42  * A file system consists of a number of cylinder groups.
43  * Each cylinder group has inodes and data.
44  *
45  * A file system is described by its super-block, which in turn
46  * describes the cylinder groups.  The super-block is critical
47  * data and is replicated in each cylinder group to protect against
48  * catastrophic loss.  This is done at `newfs' time and the critical
49  * super-block data does not change, so the copies need not be
50  * referenced further unless disaster strikes.
51  *
52  * For file system fs, the offsets of the various blocks of interest
53  * are given in the super block as:
54  *	[fs->fs_sblkno]		Super-block
55  *	[fs->fs_cblkno]		Cylinder group block
56  *	[fs->fs_iblkno]		Inode blocks
57  *	[fs->fs_dblkno]		Data blocks
58  * The beginning of cylinder group cg in fs, is given by
59  * the ``cgbase(fs, cg)'' macro.
60  *
61  * The first boot and super blocks are given in absolute disk addresses.
62  * The byte-offset forms are preferred, as they don't imply a sector size.
63  */
64 #define BBSIZE		8192
65 #define SBSIZE		8192
66 #define	BBOFF		((off_t)(0))
67 #define	SBOFF		((off_t)(BBOFF + BBSIZE))
68 #define	BBLOCK		((ufs_daddr_t)(0))
69 #define	SBLOCK		((ufs_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
70 
71 /*
72  * Addresses stored in inodes are capable of addressing fragments
73  * of `blocks'. File system blocks of at most size MAXBSIZE can
74  * be optionally broken into 2, 4, or 8 pieces, each of which is
75  * addressable; these pieces may be DEV_BSIZE, or some multiple of
76  * a DEV_BSIZE unit.
77  *
78  * Large files consist of exclusively large data blocks.  To avoid
79  * undue wasted disk space, the last data block of a small file may be
80  * allocated as only as many fragments of a large block as are
81  * necessary.  The file system format retains only a single pointer
82  * to such a fragment, which is a piece of a single large block that
83  * has been divided.  The size of such a fragment is determinable from
84  * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
85  *
86  * The file system records space availability at the fragment level;
87  * to determine block availability, aligned fragments are examined.
88  */
89 
90 /*
91  * MINBSIZE is the smallest allowable block size.
92  * In order to insure that it is possible to create files of size
93  * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
94  * MINBSIZE must be big enough to hold a cylinder group block,
95  * thus changes to (struct cg) must keep its size within MINBSIZE.
96  * Note that super blocks are always of size SBSIZE,
97  * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
98  */
99 #define MINBSIZE	4096
100 
101 /*
102  * The path name on which the file system is mounted is maintained
103  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
104  * the super block for this name.
105  */
106 #define MAXMNTLEN	512
107 
108 /*
109  * There is a 128-byte region in the superblock reserved for in-core
110  * pointers to summary information. Originally this included an array
111  * of pointers to blocks of struct csum; now there are just three
112  * pointers and the remaining space is padded with fs_ocsp[].
113  *
114  * NOCSPTRS determines the size of this padding. One pointer (fs_csp)
115  * is taken away to point to a contiguous array of struct csum for
116  * all cylinder groups; a second (fs_maxcluster) points to an array
117  * of cluster sizes that is computed as cylinder groups are inspected,
118  * and the third points to an array that tracks the creation of new
119  * directories.
120  */
121 #define	NOCSPTRS	((128 / sizeof(void *)) - 3)
122 
123 /*
124  * A summary of contiguous blocks of various sizes is maintained
125  * in each cylinder group. Normally this is set by the initial
126  * value of fs_maxcontig. To conserve space, a maximum summary size
127  * is set by FS_MAXCONTIG.
128  */
129 #define FS_MAXCONTIG	16
130 
131 /*
132  * MINFREE gives the minimum acceptable percentage of file system
133  * blocks which may be free. If the freelist drops below this level
134  * only the superuser may continue to allocate blocks. This may
135  * be set to 0 if no reserve of free blocks is deemed necessary,
136  * however throughput drops by fifty percent if the file system
137  * is run at between 95% and 100% full; thus the minimum default
138  * value of fs_minfree is 5%. However, to get good clustering
139  * performance, 10% is a better choice. hence we use 10% as our
140  * default value. With 10% free space, fragmentation is not a
141  * problem, so we choose to optimize for time.
142  */
143 #define MINFREE		8
144 #define DEFAULTOPT	FS_OPTTIME
145 
146 /*
147  * Grigoriy Orlov <gluk@ptci.ru> has done some extensive work to fine
148  * tune the layout preferences for directories within a filesystem.
149  * His algorithm can be tuned by adjusting the following parameters
150  * which tell the system the average file size and the average number
151  * of files per directory. These defaults are well selected for typical
152  * filesystems, but may need to be tuned for odd cases like filesystems
153  * being used for sqiud caches or news spools.
154  */
155 #define AVFILESIZ	16384	/* expected average file size */
156 #define AFPDIR		64	/* expected number of files per directory */
157 
158 /*
159  * The maximum number of snapshot nodes that can be associated
160  * with each filesystem. This limit affects only the number of
161  * snapshot files that can be recorded within the superblock so
162  * that they can be found when the filesystem is mounted. However,
163  * maintaining too many will slow the filesystem performance, so
164  * having this limit is a good idea.
165  */
166 #define FSMAXSNAP 20
167 
168 /*
169  * Used to identify special blocks in snapshots:
170  *
171  * BLK_NOCOPY - A block that was unallocated at the time the snapshot
172  *	was taken, hence does not need to be copied when written.
173  * BLK_SNAP - A block held by another snapshot that is not needed by this
174  *	snapshot. When the other snapshot is freed, the BLK_SNAP entries
175  *	are converted to BLK_NOCOPY. These are needed to allow fsck to
176  *	identify blocks that are in use by other snapshots (which are
177  *	expunged from this snapshot).
178  */
179 #define BLK_NOCOPY ((ufs_daddr_t)(1))
180 #define BLK_SNAP ((ufs_daddr_t)(2))
181 
182 /*
183  * Sysctl values for the fast filesystem.
184  */
185 #define	FFS_ADJ_REFCNT		 1	/* adjust inode reference count */
186 #define	FFS_ADJ_BLKCNT		 2	/* adjust inode used block count */
187 #define	FFS_BLK_FREE		 3	/* free range of blocks in map */
188 #define	FFS_DIR_FREE		 4	/* free specified dir inodes in map */
189 #define	FFS_FILE_FREE		 5	/* free specified file inodes in map */
190 #define	FFS_SET_FLAGS		 6	/* set filesystem flags */
191 #define	FFS_MAXID		 7	/* number of valid ffs ids */
192 
193 /*
194  * Command structure passed in to the filesystem to adjust filesystem values.
195  */
196 #define	FFS_CMD_VERSION		0x05181979	/* version ID */
197 struct fsck_cmd {
198 	int	version;	/* version of command structure */
199 	int	handle;		/* reference to filesystem to be changed */
200 	off_t	value;		/* inode or block number to be affected */
201 	long	size;		/* amount or range to be adjusted */
202 };
203 
204 /*
205  * Per cylinder group information; summarized in blocks allocated
206  * from first cylinder group data blocks.  These blocks have to be
207  * read in from fs_csaddr (size fs_cssize) in addition to the
208  * super block.
209  */
210 struct csum {
211 	int32_t	cs_ndir;		/* number of directories */
212 	int32_t	cs_nbfree;		/* number of free blocks */
213 	int32_t	cs_nifree;		/* number of free inodes */
214 	int32_t	cs_nffree;		/* number of free frags */
215 };
216 
217 /*
218  * Super block for an FFS file system.
219  */
220 struct fs {
221 	int32_t	 fs_firstfield;		/* historic file system linked list, */
222 	int32_t	 fs_unused_1;		/*     used for incore super blocks */
223 	ufs_daddr_t fs_sblkno;		/* addr of super-block in filesys */
224 	ufs_daddr_t fs_cblkno;		/* offset of cyl-block in filesys */
225 	ufs_daddr_t fs_iblkno;		/* offset of inode-blocks in filesys */
226 	ufs_daddr_t fs_dblkno;		/* offset of first data after cg */
227 	int32_t	 fs_cgoffset;		/* cylinder group offset in cylinder */
228 	int32_t	 fs_cgmask;		/* used to calc mod fs_ntrak */
229 	ufs_time_t fs_time;		/* last time written */
230 	int32_t	 fs_size;		/* number of blocks in fs */
231 	int32_t	 fs_dsize;		/* number of data blocks in fs */
232 	int32_t	 fs_ncg;		/* number of cylinder groups */
233 	int32_t	 fs_bsize;		/* size of basic blocks in fs */
234 	int32_t	 fs_fsize;		/* size of frag blocks in fs */
235 	int32_t	 fs_frag;		/* number of frags in a block in fs */
236 /* these are configuration parameters */
237 	int32_t	 fs_minfree;		/* minimum percentage of free blocks */
238 	int32_t	 fs_rotdelay;		/* num of ms for optimal next block */
239 	int32_t	 fs_rps;		/* disk revolutions per second */
240 /* these fields can be computed from the others */
241 	int32_t	 fs_bmask;		/* ``blkoff'' calc of blk offsets */
242 	int32_t	 fs_fmask;		/* ``fragoff'' calc of frag offsets */
243 	int32_t	 fs_bshift;		/* ``lblkno'' calc of logical blkno */
244 	int32_t	 fs_fshift;		/* ``numfrags'' calc number of frags */
245 /* these are configuration parameters */
246 	int32_t	 fs_maxcontig;		/* max number of contiguous blks */
247 	int32_t	 fs_maxbpg;		/* max number of blks per cyl group */
248 /* these fields can be computed from the others */
249 	int32_t	 fs_fragshift;		/* block to frag shift */
250 	int32_t	 fs_fsbtodb;		/* fsbtodb and dbtofsb shift constant */
251 	int32_t	 fs_sbsize;		/* actual size of super block */
252 	int32_t	 fs_csmask;		/* csum block offset (now unused) */
253 	int32_t	 fs_csshift;		/* csum block number (now unused) */
254 	int32_t	 fs_nindir;		/* value of NINDIR */
255 	int32_t	 fs_inopb;		/* value of INOPB */
256 	int32_t	 fs_nspf;		/* value of NSPF */
257 /* yet another configuration parameter */
258 	int32_t	 fs_optim;		/* optimization preference, see below */
259 /* these fields are derived from the hardware */
260 	int32_t	 fs_npsect;		/* # sectors/track including spares */
261 	int32_t	 fs_interleave;		/* hardware sector interleave */
262 	int32_t	 fs_trackskew;		/* sector 0 skew, per track */
263 /* fs_id takes the space of the unused fs_headswitch and fs_trkseek fields */
264 	int32_t	 fs_id[2];		/* unique filesystem id */
265 /* sizes determined by number of cylinder groups and their sizes */
266 	ufs_daddr_t fs_csaddr;		/* blk addr of cyl grp summary area */
267 	int32_t	 fs_cssize;		/* size of cyl grp summary area */
268 	int32_t	 fs_cgsize;		/* cylinder group size */
269 /* these fields are derived from the hardware */
270 	int32_t	 fs_ntrak;		/* tracks per cylinder */
271 	int32_t	 fs_nsect;		/* sectors per track */
272 	int32_t  fs_spc;			/* sectors per cylinder */
273 /* this comes from the disk driver partitioning */
274 	int32_t	 fs_ncyl;		/* cylinders in file system */
275 /* these fields can be computed from the others */
276 	int32_t	 fs_cpg;			/* cylinders per group */
277 	int32_t	 fs_ipg;			/* inodes per group */
278 	int32_t	 fs_fpg;			/* blocks per group * fs_frag */
279 /* this data must be re-computed after crashes */
280 	struct	csum fs_cstotal;	/* cylinder summary information */
281 /* these fields are cleared at mount time */
282 	int8_t   fs_fmod;		/* super block modified flag */
283 	int8_t   fs_clean;		/* file system is clean flag */
284 	int8_t 	 fs_ronly;		/* mounted read-only flag */
285 	int8_t   fs_flags;		/* see FS_ flags below */
286 	u_char	 fs_fsmnt[MAXMNTLEN];	/* name mounted on */
287 /* these fields retain the current block allocation info */
288 	int32_t	 fs_cgrotor;		/* last cg searched */
289 	void 	*fs_ocsp[NOCSPTRS];	/* padding; was list of fs_cs buffers */
290 	u_int8_t *fs_contigdirs;	/* # of contiguously allocated dirs */
291 	struct csum *fs_csp;		/* cg summary info buffer for fs_cs */
292 	int32_t	*fs_maxcluster;		/* max cluster in each cyl group */
293 	int32_t	 fs_cpc;		/* cyl per cycle in postbl */
294 	int16_t	 fs_opostbl[16][8];	/* old rotation block list head */
295 	int32_t	 fs_snapinum[FSMAXSNAP];/* list of snapshot inode numbers */
296 	int32_t	 fs_avgfilesize;	/* expected average file size */
297 	int32_t	 fs_avgfpdir;		/* expected # of files per directory */
298 	int32_t	 fs_sparecon[26];	/* reserved for future constants */
299 	int32_t	 fs_pendingblocks;	/* blocks in process of being freed */
300 	int32_t	 fs_pendinginodes;	/* inodes in process of being freed */
301 	int32_t	 fs_contigsumsize;	/* size of cluster summary array */
302 	int32_t	 fs_maxsymlinklen;	/* max length of an internal symlink */
303 	int32_t	 fs_inodefmt;		/* format of on-disk inodes */
304 	u_int64_t fs_maxfilesize;	/* maximum representable file size */
305 	int64_t	 fs_qbmask;		/* ~fs_bmask for use with 64-bit size */
306 	int64_t	 fs_qfmask;		/* ~fs_fmask for use with 64-bit size */
307 	int32_t	 fs_state;		/* validate fs_clean field */
308 	int32_t	 fs_postblformat;	/* format of positional layout tables */
309 	int32_t	 fs_nrpos;		/* number of rotational positions */
310 	int32_t	 fs_postbloff;		/* (u_int16) rotation block list head */
311 	int32_t	 fs_rotbloff;		/* (u_int8) blocks for each rotation */
312 	int32_t	 fs_magic;		/* magic number */
313 	u_int8_t fs_space[1];		/* list of blocks for each rotation */
314 /* actually longer */
315 };
316 
317 /*
318  * Filesystem identification
319  */
320 #define	FS_MAGIC	0x011954	/* the fast filesystem magic number */
321 #define	FS_OKAY		0x7c269d38	/* superblock checksum */
322 #define FS_42INODEFMT	-1		/* 4.2BSD inode format */
323 #define FS_44INODEFMT	2		/* 4.4BSD inode format */
324 
325 /*
326  * Preference for optimization.
327  */
328 #define FS_OPTTIME	0	/* minimize allocation time */
329 #define FS_OPTSPACE	1	/* minimize disk fragmentation */
330 
331 /*
332  * Filesystem flags.
333  *
334  * Note that the FS_NEEDSFSCK flag is set and cleared only by the
335  * fsck utility. It is set when background fsck finds an unexpected
336  * inconsistency which requires a traditional foreground fsck to be
337  * run. Such inconsistencies should only be found after an uncorrectable
338  * disk error. A foreground fsck will clear the FS_NEEDSFSCK flag when
339  * it has successfully cleaned up the filesystem. The kernel uses this
340  * flag to enforce that inconsistent filesystems be mounted read-only.
341  */
342 #define FS_UNCLEAN    0x01	/* filesystem not clean at mount */
343 #define FS_DOSOFTDEP  0x02	/* filesystem using soft dependencies */
344 #define FS_NEEDSFSCK  0x04	/* filesystem needs sync fsck before mount */
345 
346 /*
347  * Rotational layout table format types
348  */
349 #define FS_42POSTBLFMT		-1	/* 4.2BSD rotational table format */
350 #define FS_DYNAMICPOSTBLFMT	1	/* dynamic rotational table format */
351 /*
352  * Macros for access to superblock array structures
353  */
354 #define fs_postbl(fs, cylno) \
355     (((fs)->fs_postblformat == FS_42POSTBLFMT) \
356     ? ((fs)->fs_opostbl[cylno]) \
357     : ((int16_t *)((u_int8_t *)(fs) + \
358 	(fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
359 #define fs_rotbl(fs) \
360     (((fs)->fs_postblformat == FS_42POSTBLFMT) \
361     ? ((fs)->fs_space) \
362     : ((u_int8_t *)((u_int8_t *)(fs) + (fs)->fs_rotbloff)))
363 
364 /*
365  * The size of a cylinder group is calculated by CGSIZE. The maximum size
366  * is limited by the fact that cylinder groups are at most one block.
367  * Its size is derived from the size of the maps maintained in the
368  * cylinder group and the (struct cg) size.
369  */
370 #define CGSIZE(fs) \
371     /* base cg */	(sizeof(struct cg) + sizeof(int32_t) + \
372     /* blktot size */	(fs)->fs_cpg * sizeof(int32_t) + \
373     /* blks size */	(fs)->fs_cpg * (fs)->fs_nrpos * sizeof(int16_t) + \
374     /* inode map */	howmany((fs)->fs_ipg, NBBY) + \
375     /* block map */	howmany((fs)->fs_cpg * (fs)->fs_spc / NSPF(fs), NBBY) +\
376     /* if present */	((fs)->fs_contigsumsize <= 0 ? 0 : \
377     /* cluster sum */	(fs)->fs_contigsumsize * sizeof(int32_t) + \
378     /* cluster map */	howmany((fs)->fs_cpg * (fs)->fs_spc / NSPB(fs), NBBY)))
379 
380 /*
381  * Convert cylinder group to base address of its global summary info.
382  */
383 #define fs_cs(fs, indx) fs_csp[indx]
384 
385 /*
386  * Cylinder group block for a file system.
387  */
388 #define	CG_MAGIC	0x090255
389 struct cg {
390 	int32_t	 cg_firstfield;		/* historic cyl groups linked list */
391 	int32_t	 cg_magic;		/* magic number */
392 	ufs_time_t cg_time;		/* time last written */
393 	int32_t	 cg_cgx;		/* we are the cgx'th cylinder group */
394 	int16_t	 cg_ncyl;		/* number of cyl's this cg */
395 	int16_t	 cg_niblk;		/* number of inode blocks this cg */
396 	int32_t	 cg_ndblk;		/* number of data blocks this cg */
397 	struct	csum cg_cs;		/* cylinder summary information */
398 	int32_t	 cg_rotor;		/* position of last used block */
399 	int32_t	 cg_frotor;		/* position of last used frag */
400 	int32_t	 cg_irotor;		/* position of last used inode */
401 	int32_t	 cg_frsum[MAXFRAG];	/* counts of available frags */
402 	int32_t	 cg_btotoff;		/* (int32) block totals per cylinder */
403 	int32_t	 cg_boff;		/* (u_int16) free block positions */
404 	int32_t	 cg_iusedoff;		/* (u_int8) used inode map */
405 	int32_t	 cg_freeoff;		/* (u_int8) free block map */
406 	int32_t	 cg_nextfreeoff;	/* (u_int8) next available space */
407 	int32_t	 cg_clustersumoff;	/* (u_int32) counts of avail clusters */
408 	int32_t	 cg_clusteroff;		/* (u_int8) free cluster map */
409 	int32_t	 cg_nclusterblks;	/* number of clusters this cg */
410 	int32_t	 cg_sparecon[13];	/* reserved for future use */
411 	u_int8_t cg_space[1];		/* space for cylinder group maps */
412 /* actually longer */
413 };
414 
415 /*
416  * Macros for access to cylinder group array structures
417  */
418 #define cg_blktot(cgp) \
419     (((cgp)->cg_magic != CG_MAGIC) \
420     ? (((struct ocg *)(cgp))->cg_btot) \
421     : ((int32_t *)((u_int8_t *)(cgp) + (cgp)->cg_btotoff)))
422 #define cg_blks(fs, cgp, cylno) \
423     (((cgp)->cg_magic != CG_MAGIC) \
424     ? (((struct ocg *)(cgp))->cg_b[cylno]) \
425     : ((int16_t *)((u_int8_t *)(cgp) + \
426 	(cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
427 #define cg_inosused(cgp) \
428     (((cgp)->cg_magic != CG_MAGIC) \
429     ? (((struct ocg *)(cgp))->cg_iused) \
430     : ((u_int8_t *)((u_int8_t *)(cgp) + (cgp)->cg_iusedoff)))
431 #define cg_blksfree(cgp) \
432     (((cgp)->cg_magic != CG_MAGIC) \
433     ? (((struct ocg *)(cgp))->cg_free) \
434     : ((u_int8_t *)((u_int8_t *)(cgp) + (cgp)->cg_freeoff)))
435 #define cg_chkmagic(cgp) \
436     ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
437 #define cg_clustersfree(cgp) \
438     ((u_int8_t *)((u_int8_t *)(cgp) + (cgp)->cg_clusteroff))
439 #define cg_clustersum(cgp) \
440     ((int32_t *)((u_int8_t *)(cgp) + (cgp)->cg_clustersumoff))
441 
442 /*
443  * The following structure is defined
444  * for compatibility with old file systems.
445  */
446 struct ocg {
447 	int32_t	 cg_firstfield;		/* historic linked list of cyl groups */
448 	int32_t	 cg_unused_1;		/*     used for incore cyl groups */
449 	ufs_time_t cg_time;		/* time last written */
450 	int32_t	 cg_cgx;		/* we are the cgx'th cylinder group */
451 	int16_t	 cg_ncyl;		/* number of cyl's this cg */
452 	int16_t	 cg_niblk;		/* number of inode blocks this cg */
453 	int32_t	 cg_ndblk;		/* number of data blocks this cg */
454 	struct	csum cg_cs;		/* cylinder summary information */
455 	int32_t	 cg_rotor;		/* position of last used block */
456 	int32_t	 cg_frotor;		/* position of last used frag */
457 	int32_t	 cg_irotor;		/* position of last used inode */
458 	int32_t	 cg_frsum[8];		/* counts of available frags */
459 	int32_t	 cg_btot[32];		/* block totals per cylinder */
460 	int16_t	 cg_b[32][8];		/* positions of free blocks */
461 	u_int8_t cg_iused[256];		/* used inode map */
462 	int32_t	 cg_magic;		/* magic number */
463 	u_int8_t cg_free[1];		/* free block map */
464 /* actually longer */
465 };
466 
467 /*
468  * Turn file system block numbers into disk block addresses.
469  * This maps file system blocks to device size blocks.
470  */
471 #define fsbtodb(fs, b)	((b) << (fs)->fs_fsbtodb)
472 #define	dbtofsb(fs, b)	((b) >> (fs)->fs_fsbtodb)
473 
474 /*
475  * Cylinder group macros to locate things in cylinder groups.
476  * They calc file system addresses of cylinder group data structures.
477  */
478 #define	cgbase(fs, c)	((ufs_daddr_t)((fs)->fs_fpg * (c)))
479 #define	cgdmin(fs, c)	(cgstart(fs, c) + (fs)->fs_dblkno)	/* 1st data */
480 #define	cgimin(fs, c)	(cgstart(fs, c) + (fs)->fs_iblkno)	/* inode blk */
481 #define	cgsblock(fs, c)	(cgstart(fs, c) + (fs)->fs_sblkno)	/* super blk */
482 #define	cgtod(fs, c)	(cgstart(fs, c) + (fs)->fs_cblkno)	/* cg block */
483 #define cgstart(fs, c)							\
484 	(cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
485 
486 /*
487  * Macros for handling inode numbers:
488  *     inode number to file system block offset.
489  *     inode number to cylinder group number.
490  *     inode number to file system block address.
491  */
492 #define	ino_to_cg(fs, x)	((x) / (fs)->fs_ipg)
493 #define	ino_to_fsba(fs, x)						\
494 	((ufs_daddr_t)(cgimin(fs, ino_to_cg(fs, x)) +			\
495 	    (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
496 #define	ino_to_fsbo(fs, x)	((x) % INOPB(fs))
497 
498 /*
499  * Give cylinder group number for a file system block.
500  * Give cylinder group block number for a file system block.
501  */
502 #define	dtog(fs, d)	((d) / (fs)->fs_fpg)
503 #define	dtogd(fs, d)	((d) % (fs)->fs_fpg)
504 
505 /*
506  * Extract the bits for a block from a map.
507  * Compute the cylinder and rotational position of a cyl block addr.
508  */
509 #define blkmap(fs, map, loc) \
510     (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
511 #define cbtocylno(fs, bno) \
512     ((bno) * NSPF(fs) / (fs)->fs_spc)
513 #define cbtorpos(fs, bno) \
514     (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
515      (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
516      (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
517 
518 /*
519  * The following macros optimize certain frequently calculated
520  * quantities by using shifts and masks in place of divisions
521  * modulos and multiplications.
522  */
523 #define blkoff(fs, loc)		/* calculates (loc % fs->fs_bsize) */ \
524 	((loc) & (fs)->fs_qbmask)
525 #define fragoff(fs, loc)	/* calculates (loc % fs->fs_fsize) */ \
526 	((loc) & (fs)->fs_qfmask)
527 #define lblktosize(fs, blk)	/* calculates ((off_t)blk * fs->fs_bsize) */ \
528 	((off_t)(blk) << (fs)->fs_bshift)
529 /* Use this only when `blk' is known to be small, e.g., < NDADDR. */
530 #define smalllblktosize(fs, blk)    /* calculates (blk * fs->fs_bsize) */ \
531 	((blk) << (fs)->fs_bshift)
532 #define lblkno(fs, loc)		/* calculates (loc / fs->fs_bsize) */ \
533 	((loc) >> (fs)->fs_bshift)
534 #define numfrags(fs, loc)	/* calculates (loc / fs->fs_fsize) */ \
535 	((loc) >> (fs)->fs_fshift)
536 #define blkroundup(fs, size)	/* calculates roundup(size, fs->fs_bsize) */ \
537 	(((size) + (fs)->fs_qbmask) & (fs)->fs_bmask)
538 #define fragroundup(fs, size)	/* calculates roundup(size, fs->fs_fsize) */ \
539 	(((size) + (fs)->fs_qfmask) & (fs)->fs_fmask)
540 #define fragstoblks(fs, frags)	/* calculates (frags / fs->fs_frag) */ \
541 	((frags) >> (fs)->fs_fragshift)
542 #define blkstofrags(fs, blks)	/* calculates (blks * fs->fs_frag) */ \
543 	((blks) << (fs)->fs_fragshift)
544 #define fragnum(fs, fsb)	/* calculates (fsb % fs->fs_frag) */ \
545 	((fsb) & ((fs)->fs_frag - 1))
546 #define blknum(fs, fsb)		/* calculates rounddown(fsb, fs->fs_frag) */ \
547 	((fsb) &~ ((fs)->fs_frag - 1))
548 
549 /*
550  * Determine the number of available frags given a
551  * percentage to hold in reserve.
552  */
553 #define freespace(fs, percentreserved) \
554 	(blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
555 	(fs)->fs_cstotal.cs_nffree - \
556 	((off_t)((fs)->fs_dsize) * (percentreserved) / 100))
557 
558 /*
559  * Determining the size of a file block in the file system.
560  */
561 #define blksize(fs, ip, lbn) \
562 	(((lbn) >= NDADDR || (ip)->i_size >= smalllblktosize(fs, (lbn) + 1)) \
563 	    ? (fs)->fs_bsize \
564 	    : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
565 #define dblksize(fs, dip, lbn) \
566 	(((lbn) >= NDADDR || \
567 	  (dip)->di_size >= (u_int64_t)smalllblktosize(fs, (lbn) + 1)) \
568 	    ? (fs)->fs_bsize \
569 	    : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
570 #define sblksize(fs, size, lbn) \
571 	(((lbn) >= NDADDR || (size) >= ((lbn) + 1) << (fs)->fs_bshift) \
572 	  ? (fs)->fs_bsize \
573 	  : (fragroundup(fs, blkoff(fs, (size)))))
574 
575 
576 /*
577  * Number of disk sectors per block/fragment; assumes DEV_BSIZE byte
578  * sector size.
579  */
580 #define	NSPB(fs)	((fs)->fs_nspf << (fs)->fs_fragshift)
581 #define	NSPF(fs)	((fs)->fs_nspf)
582 
583 /*
584  * Number of inodes in a secondary storage block/fragment.
585  */
586 #define	INOPB(fs)	((fs)->fs_inopb)
587 #define	INOPF(fs)	((fs)->fs_inopb >> (fs)->fs_fragshift)
588 
589 /*
590  * Number of indirects in a file system block.
591  */
592 #define	NINDIR(fs)	((fs)->fs_nindir)
593 
594 extern int inside[], around[];
595 extern u_char *fragtbl[];
596 
597 #endif
598