#include <sys/param.h> #include <sys/types.h> #include <sys/fs/ufs_fs.h>
A file system is described by its super-block, and by the information in the cylinder group blocks. The super-block is critical data and is replicated before each cylinder group block to protect against catastrophic loss. This is done at mkfs time; the critical super-block data does not change, so the copies need not normally be referenced further.
/*
* Super block for a file system.
*/
#define FS_MAGIC 0x011954
#define FSACTIVE 0x5e72d81a /* fs_state: mounted */
#define FSOKAY 0x7c269d38 /* fs_state: clean */
#define FSBAD 0xcb096f43 /* fs_state: bad root */
struct fs {
struct fs *fs_link; /* linked list of file systems */
struct fs *fs_rlink; /* used for incore super blocks */
daddr_t fs_sblkno; /* addr of super-block in filesys */
daddr_t fs_cblkno; /* offset of cyl-block in filesys */
daddr_t fs_iblkno; /* offset of inode-blocks in filesys */
daddr_t fs_dblkno; /* offset of first data after cg */
long fs_cgoffset; /* cylinder group offset in cylinder */
long fs_cgmask; /* used to calc mod fs_ntrak */
time_t fs_time; /* last time written */
long fs_size; /* number of blocks in fs */
long fs_dsize; /* number of data blocks in fs */
long fs_ncg; /* number of cylinder groups */
long fs_bsize; /* size of basic blocks in fs */
long fs_fsize; /* size of frag blocks in fs */
long fs_frag; /* number of frags in a block in fs */
/* these are configuration parameters */
long fs_minfree; /* minimum percentage of free blocks */
long fs_rotdelay; /* num of ms for optimal next block */
long fs_rps; /* disk revolutions per second */
/* these fields can be computed from the others */
long fs_bmask; /* ``blkoff'' calc of blk offsets */
long fs_fmask; /* ``fragoff'' calc of frag offsets */
long fs_bshift; /* ``lblkno'' calc of logical blkno */
long fs_fshift; /* ``numfrags'' calc number of frags */
/* these are configuration parameters */
long fs_maxcontig; /* max number of contiguous blks */
long fs_maxbpg; /* max number of blks per cyl group */
/* these fields can be computed from the others */
long fs_fragshift; /* block to frag shift */
long fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
long fs_sbsize; /* actual size of super block */
long fs_csmask; /* csum block offset */
long fs_csshift; /* csum block number */
long fs_nindir; /* value of NINDIR */
long fs_inopb; /* value of INOPB */
long fs_nspf; /* value of NSPF */
long fs_optim; /* optimization preference, see below */
long fs_state; /* file system state */
long fs_sparecon[2]; /* reserved for future constants */
/* a unique id for this filesystem (currently unused and unmaintained) */
long fs_id[2]; /* file system id */
/* 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 flag */
char fs_fsmnt[MAXMNTLEN]; /* name mounted on */
/* 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 */
};
/*
* 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 */
};