fs.h

<B>Digital的Unix操作系统VAX 4.2源码</B>

	long	fs_inopb;		/* value of INOPB */
	long	fs_nspf;		/* value of NSPF */
	long	fs_optim;		/* optimization preference, see below */
	long	fs_sparecon[5];		/* reserved for future constants */
/* sizes determined by number of cylinder groups and their sizes */
	daddr_t fs_csaddr;		/* blk addr of cyl grp summary area */
	long	fs_cssize;		/* size of cyl grp summary area */
	long	fs_cgsize;		/* cylinder group size */
/* these fields should be derived from the hardware */
	long	fs_ntrak;		/* tracks per cylinder */
	long	fs_nsect;		/* sectors per track */
	long  	fs_spc;   		/* sectors per cylinder */
/* this comes from the disk driver partitioning */
	long	fs_ncyl;   		/* cylinders in file system */
/* these fields can be computed from the others */
	long	fs_cpg;			/* cylinders per group */
	long	fs_ipg;			/* inodes per group */
	long	fs_fpg;			/* blocks per group * fs_frag */
/* this data must be re-computed after crashes */
	struct	csum fs_cstotal;	/* cylinder summary information */
/* these fields are cleared at mount time */
	char   	fs_fmod;    		/* super block modified flag */
	char   	fs_clean;    		/* file system is clean flag */
	char   	fs_ronly;   		/* mounted read-only flag */
	char   	fs_flags;		/* currently unused flags */
#define	fs_cleantimer	fs_flags	/* Clean byte timeout factor */
	char	fs_fsmnt[MAXMNTLEN];	/* name mounted on */
/* Space for next three fields taken from fs_fsmnt (12 bytes) */
	char	fs_deftimer;		/* Default value for fs_cleantimer */
	char	fs_extra[3];		/* Currently unused */
	time_t	fs_lastfsck;		/* Time of last fsck */
	u_int	fs_gennum;		/* Unique file system id */
/* these fields retain the current block allocation info */
	long	fs_cgrotor;		/* last cg searched */
	struct	csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */
	long	fs_cpc;			/* cyl per cycle in postbl */
	short	fs_postbl[MAXCPG][NRPOS];/* head of blocks for each rotation */
	long	fs_magic;		/* magic number */
	u_char	fs_rotbl[1];		/* list of blocks for each rotation */
/* actually longer */
};

/*
 * Preference for optimization.
 */
#define FS_OPTTIME	0	/* minimize allocation time */
#define FS_OPTSPACE	1	/* minimize disk fragmentation */

/*
 * Convert cylinder group to base address of its global summary info.
 *
 * N.B. This macro assumes that sizeof(struct csum) is a power of two.
 */
#define fs_cs(fs, indx) \
	fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]

/*
 * MAXBPC bounds the size of the rotational layout tables and
 * is limited by the fact that the super block is of size SBSIZE.
 * The size of these tables is INVERSELY proportional to the block
 * size of the file system. It is aggravated by sector sizes that
 * are not powers of two, as this increases the number of cylinders
 * included before the rotational pattern repeats (fs_cpc).
 * Its size is derived from the number of bytes remaining in (struct fs)
 */
#define	MAXBPC	(SBSIZE - sizeof (struct fs))

/*
 * Cylinder group block for a file system.
 */
#define	CG_MAGIC	0x090255
struct	cg {
	struct	cg *cg_link;		/* linked list of cyl groups */
	struct	cg *cg_rlink;		/*     used for incore cyl groups */
	time_t	cg_time;		/* time last written */
	long	cg_cgx;			/* we are the cgx'th cylinder group */
	short	cg_ncyl;		/* number of cyl's this cg */
	short	cg_niblk;		/* number of inode blocks this cg */
	long	cg_ndblk;		/* number of data blocks this cg */
	struct	csum cg_cs;		/* cylinder summary information */
	long	cg_rotor;		/* position of last used block */
	long	cg_frotor;		/* position of last used frag */
	long	cg_irotor;		/* position of last used inode */
	long	cg_frsum[MAXFRAG];	/* counts of available frags */
	long	cg_btot[MAXCPG];	/* block totals per cylinder */
	short	cg_b[MAXCPG][NRPOS];	/* positions of free blocks */
	char	cg_iused[MAXIPG/NBBY];	/* used inode map */
	long	cg_magic;		/* magic number */
	u_char	cg_free[1];		/* free block map */
/* actually longer */
};

/*
 * MAXBPG bounds the number of blocks of data per cylinder group,
 * and is limited by the fact that cylinder groups are at most one block.
 * Its size is derived from the size of blocks and the (struct cg) size,
 * by the number of remaining bits.
 */
#define	MAXBPG(fs) \
	(fragstoblks((fs), (NBBY * ((fs)->fs_bsize - (sizeof (struct cg))))))

/*
 * Turn file system block numbers into disk block addresses.
 * This maps file system blocks to device size blocks.
 */
#define fsbtodb(fs, b)	((b) << (fs)->fs_fsbtodb)
#define	dbtofsb(fs, b)	((b) >> (fs)->fs_fsbtodb)

/*
 * Cylinder group macros to locate things in cylinder groups.
 * They calc file system addresses of cylinder group data structures.
 */
#define	cgbase(fs, c)	((daddr_t)((fs)->fs_fpg * (c)))
#define cgstart(fs, c) \
	(cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
#define	cgsblock(fs, c)	(cgstart(fs, c) + (fs)->fs_sblkno)	/* super blk */
#define	cgtod(fs, c)	(cgstart(fs, c) + (fs)->fs_cblkno)	/* cg block */
#define	cgimin(fs, c)	(cgstart(fs, c) + (fs)->fs_iblkno)	/* inode blk */
#define	cgdmin(fs, c)	(cgstart(fs, c) + (fs)->fs_dblkno)	/* 1st data */

/*
 * Macros for handling inode numbers:
 *     inode number to file system block offset.
 *     inode number to cylinder group number.
 *     inode number to file system block address.
 */
#define	itoo(fs, x)	((x) % INOPB(fs))
#define	itog(fs, x)	((x) / (fs)->fs_ipg)
#define	itod(fs, x) \
	((daddr_t)(cgimin(fs, itog(fs, x)) + \
	(blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))

/*
 * Give cylinder group number for a file system block.
 * Give cylinder group block number for a file system block.
 */
#define	dtog(fs, d)	((d) / (fs)->fs_fpg)
#define	dtogd(fs, d)	((d) % (fs)->fs_fpg)

/*
 * Extract the bits for a block from a map.
 * Compute the cylinder and rotational position of a cyl block addr.
 */
#define blkmap(fs, map, loc) \
    (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
#define cbtocylno(fs, bno) \
	((bno) * NSPF(fs) / (fs)->fs_spc)
#define cbtorpos(fs, bno) \
    ((bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * NRPOS / (fs)->fs_nsect)

/*
 * The following macros optimize certain frequently calculated
 * quantities by using shifts and masks in place of divisions
 * modulos and multiplications.
 */
#define blkoff(fs, loc)		/* calculates (loc % fs->fs_bsize) */ \
	((loc) & ~(fs)->fs_bmask)
#define fragoff(fs, loc)	/* calculates (loc % fs->fs_fsize) */ \
	((loc) & ~(fs)->fs_fmask)
#define lblkno(fs, loc)		/* calculates (loc / fs->fs_bsize) */ \
	((loc) >> (fs)->fs_bshift)
#define numfrags(fs, loc)	/* calculates (loc / fs->fs_fsize) */ \
	((loc) >> (fs)->fs_fshift)
#define blkroundup(fs, size)	/* calculates roundup(size, fs->fs_bsize) */ \
	(((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
#define fragroundup(fs, size)	/* calculates roundup(size, fs->fs_fsize) */ \
	(((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
#define fragstoblks(fs, frags)	/* calculates (frags / fs->fs_frag) */ \
	((frags) >> (fs)->fs_fragshift)
#define blkstofrags(fs, blks)	/* calculates (blks * fs->fs_frag) */ \
	((blks) << (fs)->fs_fragshift)
#define fragnum(fs, fsb)	/* calculates (fsb % fs->fs_frag) */ \
	((fsb) & ((fs)->fs_frag - 1))
#define blknum(fs, fsb)		/* calculates rounddown(fsb, fs->fs_frag) */ \
	((fsb) &~ ((fs)->fs_frag - 1))

/*
 * Determine the number of available frags given a
 * percentage to hold in reserve
 */
#define freespace(fs, percentreserved) \
	(blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
	(fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))

/*
 * Determining the size of a file block in the file system.
 */
#define blksize(fs, gp, lbn) \
	(((lbn) >= NDADDR || (gp)->g_size >= ((lbn) + 1) << (fs)->fs_bshift) \
	    ? (fs)->fs_bsize \
	    : (fragroundup(fs, blkoff(fs, (gp)->g_size))))
#define dblksize(fs, dip, lbn) \
	(((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
	    ? (fs)->fs_bsize \
	    : (fragroundup(fs, blkoff(fs, (dip)->di_size))))

/*
 * Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
 */
#define	NSPB(fs)	((fs)->fs_nspf << (fs)->fs_fragshift)
#define	NSPF(fs)	((fs)->fs_nspf)

/*
 * INOPB is the number of inodes in a secondary storage block.
 */
#define	INOPB(fs)	((fs)->fs_inopb)
#define	INOPF(fs)	((fs)->fs_inopb >> (fs)->fs_fragshift)

/*
 * NINDIR is the number of indirects in a file system block.
 */
#define	NINDIR(fs)	((fs)->fs_nindir)

#ifdef KERNEL
struct	fs *getfs();
#define FS(gp) ((gp)->g_mp->m_bufp->b_un.b_fs)
#endif

/* Clean byte timeout ceilings */

#define FSCLEAN_TIMEOUTFACTOR 20	/* Default clean byte time out factor */
#define FSCLEAN_UPDATES	10000		/* Default number of writes */
#define FS_CLEAN	30		/* Clean byte value */

#define CHECK_CLEAN_THRESHOLD(fs, devname, ceiling, reason) \
        { \
		if (!fs->fs_cleantimer || fs->fs_cleantimer-- <= 1) { \
			fs->fs_cleantimer = 0; \
			uprintf("Warning, %s has exceeded %d %s threshold, fsck(8) is advised\n", devname, ceiling, reason); \
		} \
	}