struct csum {
	int32_t	cs_ndir;		/* number of directories */
	int32_t	cs_nbfree;		/* number of free blocks */
	int32_t	cs_nifree;		/* number of free inodes */
	int32_t	cs_nffree;		/* number of free frags */
};
struct csum_total {
	int64_t	cs_ndir;		/* number of directories */
	int64_t	cs_nbfree;		/* number of free blocks */
	int64_t	cs_nifree;		/* number of free inodes */
	int64_t	cs_nffree;		/* number of free frags */
	int64_t	cs_numclusters;		/* number of free clusters */
	int64_t	cs_spare[3];		/* future expansion */
};

/*
 * Super block for an FFS filesystem.
 */
struct fs {
	int	 fs_firstfield;		/* historic filesystem linked list, */
	int	 fs_unused_1;		/*     used for incore super blocks */
	int	 fs_sblkno;		/* offset of super-block in filesys */
	int	 fs_cblkno;		/* offset of cyl-block in filesys */
	int	 fs_iblkno;		/* offset of inode-blocks in filesys */
	int	 fs_dblkno;		/* offset of first data after cg */
	int	 fs_old_cgoffset;	/* cylinder group offset in cylinder */
	int	 fs_old_cgmask;		/* used to calc mod fs_ntrak */
	int  fs_old_time;		/* last time written */
	int	 fs_old_size;		/* number of blocks in fs */
	int	 fs_old_dsize;		/* number of data blocks in fs */
	int	 fs_ncg;		/* number of cylinder groups */
	int	 fs_bsize;		/* size of basic blocks in fs */
	int	 fs_fsize;		/* size of frag blocks in fs */
	int	 fs_frag;		/* number of frags in a block in fs */
	int	 fs_minfree;		/* minimum percentage of free blocks */
	int	 fs_old_rotdelay;	/* num of ms for optimal next block */
	int	 fs_old_rps;		/* disk revolutions per second */
	int	 fs_bmask;		/* ``blkoff'' calc of blk offsets */
	int	 fs_fmask;		/* ``fragoff'' calc of frag offsets */
	int	 fs_bshift;		/* ``lblkno'' calc of logical blkno */
	int	 fs_fshift;		/* ``numfrags'' calc number of frags */
	int	 fs_maxcontig;		/* max number of contiguous blks */
	int	 fs_maxbpg;		/* max number of blks per cyl group */
	int	 fs_fragshift;		/* block to frag shift */
	int	 fs_fsbtodb;		/* fsbtodb and dbtofsb shift constant */
	int	 fs_sbsize;		/* actual size of super block */
	int	 fs_spare1[2];		/* old fs_csmask */
	int	 fs_nindir;		/* value of NINDIR */
	int	 fs_inopb;		/* value of INOPB */
	int	 fs_old_nspf;		/* value of NSPF */
	int	 fs_optim;		/* optimization preference, see below */
	int	 fs_old_npsect;		/* # sectors/track including spares */
	int	 fs_old_interleave;	/* hardware sector interleave */
	int	 fs_old_trackskew;	/* sector 0 skew, per track */
	int	 fs_id[2];		/* unique filesystem id */
	int	 fs_old_csaddr;		/* blk addr of cyl grp summary area */
	int	 fs_cssize;		/* size of cyl grp summary area */
	int	 fs_cgsize;		/* cylinder group size */
	int	 fs_spare2;		/* old fs_ntrak */
	int	 fs_old_nsect;		/* sectors per track */
	int  fs_old_spc;		/* sectors per cylinder */
	int	 fs_old_ncyl;		/* cylinders in filesystem */
	int	 fs_old_cpg;		/* cylinders per group */
	int	 fs_ipg;		/* inodes per group */
	int	 fs_fpg;		/* blocks per group * fs_frag */
	csum fs_old_cstotal;	/* cylinder summary information */
	int8_t   fs_fmod;		/* super block modified flag */
	int8_t   fs_clean;		/* filesystem is clean flag */
	int8_t 	 fs_ronly;		/* mounted read-only flag */
	int8_t   fs_old_flags;		/* old FS_ flags */
	u_char	 fs_fsmnt[MAXMNTLEN];	/* name mounted on */
	u_char	 fs_volname[MAXVOLLEN];	/* volume name */
	uint64_t fs_swuid;		/* system-wide uid */
	int  fs_pad;		/* due to alignment of fs_swuid */
	int	 fs_cgrotor;		/* last cg searched */
	void 	*fs_ocsp[NOCSPTRS];	/* padding; was list of fs_cs buffers */
	uint8_t *fs_contigdirs;	/* (u) # of contig. allocated dirs */
	csum *fs_csp;		/* (u) cg summary info buffer */
	int	*fs_maxcluster;		/* (u) max cluster in each cyl group */
	u_int	*fs_active;		/* (u) used by snapshots to track fs */
	int	 fs_old_cpc;		/* cyl per cycle in postbl */
	int	 fs_maxbsize;		/* maximum blocking factor permitted */
	int64_t	 fs_sparecon64[17];	/* old rotation block list head */
	int64_t	 fs_sblockloc;		/* byte offset of standard superblock */
	csum_total fs_cstotal;	/* (u) cylinder summary information */
	ufs_time_t fs_time;		/* last time written */
	int64_t	 fs_size;		/* number of blocks in fs */
	int64_t	 fs_dsize;		/* number of data blocks in fs */
	ufs2_daddr_t fs_csaddr;		/* blk addr of cyl grp summary area */
	int64_t	 fs_pendingblocks;	/* (u) blocks being freed */
	int	 fs_pendinginodes;	/* (u) inodes being freed */
	int	 fs_snapinum[FSMAXSNAP];/* list of snapshot inode numbers */
	int	 fs_avgfilesize;	/* expected average file size */
	int	 fs_avgfpdir;		/* expected # of files per directory */
	int	 fs_save_cgsize;	/* save real cg size to use fs_bsize */
	int	 fs_sparecon32[26];	/* reserved for future constants */
	int  fs_flags;		/* see FS_ flags below */
	int	 fs_contigsumsize;	/* size of cluster summary array */ 
	int	 fs_maxsymlinklen;	/* max length of an internal symlink */
	int	 fs_old_inodefmt;	/* format of on-disk inodes */
	uint64_t fs_maxfilesize;	/* maximum representable file size */
	int64_t	 fs_qbmask;		/* ~fs_bmask for use with 64-bit size */
	int64_t	 fs_qfmask;		/* ~fs_fmask for use with 64-bit size */
	int	 fs_state;		/* validate fs_clean field */
	int	 fs_old_postblformat;	/* format of positional layout tables */
	int	 fs_old_nrpos;		/* number of rotational positions */
	int	 fs_spare5[2];		/* old fs_postbloff */
	int	 fs_magic;		/* magic number */
};