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* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
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* may be used to endorse or promote products derived from this software
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* @(#)fs.h 8.1 (Berkeley) 6/11/93
* Each disk drive contains some number of file systems.
* A file system consists of a number of cylinder groups.
* Each cylinder group has inodes and data.
* A file system is described by its super-block, which in turn
* describes the cylinder groups. The super-block is critical
* data and is replicated in each cylinder group to protect against
* catastrophic loss. This is done at `newfs' time and the critical
* super-block data does not change, so the copies need not be
* referenced further unless disaster strikes.
* For file system fs, the offsets of the various blocks of interest
* are given in the super block as:
* [fs->fs_sblkno] Super-block
* [fs->fs_cblkno] Cylinder group block
* [fs->fs_iblkno] Inode blocks
* [fs->fs_dblkno] Data blocks
* The beginning of cylinder group cg in fs, is given by
* the ``cgbase(fs, cg)'' macro.
* The first boot and super blocks are given in absolute disk addresses.
* The byte-offset forms are preferred, as they don't imply a sector size.
#define BBOFF ((off_t)(0))
#define SBOFF ((off_t)(BBOFF + BBSIZE))
#define BBLOCK ((daddr_t)(0))
#define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
* Addresses stored in inodes are capable of addressing fragments
* of `blocks'. File system blocks of at most size MAXBSIZE can
* be optionally broken into 2, 4, or 8 pieces, each of which is
* addressible; these pieces may be DEV_BSIZE, or some multiple of
* Large files consist of exclusively large data blocks. To avoid
* undue wasted disk space, the last data block of a small file may be
* allocated as only as many fragments of a large block as are
* necessary. The file system format retains only a single pointer
* to such a fragment, which is a piece of a single large block that
* has been divided. The size of such a fragment is determinable from
* information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
* The file system records space availability at the fragment level;
* to determine block availability, aligned fragments are examined.
* MINBSIZE is the smallest allowable block size.
* In order to insure that it is possible to create files of size
* 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
* MINBSIZE must be big enough to hold a cylinder group block,
* thus changes to (struct cg) must keep its size within MINBSIZE.
* Note that super blocks are always of size SBSIZE,
* and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
* The path name on which the file system is mounted is maintained
* in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
* the super block for this name.
* The limit on the amount of summary information per file system
* is defined by MAXCSBUFS. It is currently parameterized for a
* maximum of two million cylinders.
* Per cylinder group information; summarized in blocks allocated
* from first cylinder group data blocks. These blocks have to be
* read in from fs_csaddr (size fs_cssize) in addition to the
* N.B. sizeof(struct csum) must be a power of two in order for
* the ``fs_cs'' macro to work (see below).
long cs_ndir
; /* number of directories */
long cs_nbfree
; /* number of free blocks */
long cs_nifree
; /* number of free inodes */
long cs_nffree
; /* number of free frags */
* Super block for a file system.
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 */
/* yet another configuration parameter */
long fs_optim
; /* optimization preference, see below */
/* these fields are derived from the hardware */
long fs_npsect
; /* # sectors/track including spares */
long fs_interleave
; /* hardware sector interleave */
long fs_trackskew
; /* sector 0 skew, per track */
long fs_headswitch
; /* head switch time, usec */
long fs_trkseek
; /* track-to-track seek, usec */
/* 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 are 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_opostbl
[16][8]; /* old rotation block list head */
long fs_sparecon
[51]; /* reserved for future constants */
long fs_maxsymlinklen
; /* max length of an internal symlink */
long fs_inodefmt
; /* format of on-disk inodes */
u_quad_t fs_maxfilesize
; /* maximum representable file size */ quad_t fs_qbmask
; /* ~fs_bmask - for use with quad size */ quad_t fs_qfmask
; /* ~fs_fmask - for use with quad size */ long fs_state
; /* validate fs_clean field */
long fs_postblformat
; /* format of positional layout tables */
long fs_nrpos
; /* number of rotaional positions */
long fs_postbloff
; /* (short) rotation block list head */
long fs_rotbloff
; /* (u_char) blocks for each rotation */
long fs_magic
; /* magic number */
u_char fs_space
[1]; /* list of blocks for each rotation */ * Filesystem idetification
#define FS_MAGIC 0x011954 /* the fast filesystem magic number */
#define FS_OKAY 0x7c269d38 /* superblock checksum */
#define FS_42INODEFMT -1 /* 4.2BSD inode format */
#define FS_44INODEFMT 2 /* 4.4BSD inode format */
* Preference for optimization.
#define FS_OPTTIME 0 /* minimize allocation time */
#define FS_OPTSPACE 1 /* minimize disk fragmentation */
* Rotational layout table format types
#define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */
#define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */
* Macros for access to superblock array structures
#define fs_postbl(fs, cylno) \
(((fs)->fs_postblformat == FS_42POSTBLFMT) \
? ((fs)->fs_opostbl[cylno]) \
: ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
(((fs)->fs_postblformat == FS_42POSTBLFMT) \
: ((u_char *)((char *)(fs) + (fs)->fs_rotbloff)))
* 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]
* Cylinder group block for a file system.
#define CG_MAGIC 0x090255
struct cg
*cg_link
; /* linked list of cyl groups */
long cg_magic
; /* magic number */
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_btotoff
; /* (long) block totals per cylinder */
long cg_boff
; /* (short) free block positions */
long cg_iusedoff
; /* (char) used inode map */
long cg_freeoff
; /* (u_char) free block map */
long cg_nextfreeoff
; /* (u_char) next available space */
long cg_sparecon
[16]; /* reserved for future use */
u_char cg_space
[1]; /* space for cylinder group maps */ * Macros for access to cylinder group array structures
(((cgp)->cg_magic != CG_MAGIC) \
? (((struct ocg *)(cgp))->cg_btot) \
: ((long *)((char *)(cgp) + (cgp)->cg_btotoff)))
#define cg_blks(fs, cgp, cylno) \
(((cgp)->cg_magic != CG_MAGIC) \
? (((struct ocg *)(cgp))->cg_b[cylno]) \
: ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
#define cg_inosused(cgp) \
(((cgp)->cg_magic != CG_MAGIC) \
? (((struct ocg *)(cgp))->cg_iused) \
: ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
#define cg_blksfree(cgp) \
(((cgp)->cg_magic != CG_MAGIC) \
? (((struct ocg *)(cgp))->cg_free) \
: ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff)))
#define cg_chkmagic(cgp) \
((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
* The following structure is defined
* for compatibility with old file systems.
struct ocg
*cg_link
; /* linked list of cyl groups */
struct ocg
*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
[8]; /* counts of available frags */
long cg_btot
[32]; /* block totals per cylinder */
short cg_b
[32][8]; /* positions of free blocks */
char cg_iused
[256]; /* used inode map */
long cg_magic
; /* magic number */
u_char cg_free
[1]; /* free block map */ * 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)))
(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)
((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 * (fs)->fs_trackskew + \
(bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
(fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
* 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_qbmask)
#define fragoff(fs, loc) /* calculates (loc % fs->fs_fsize) */ \
((loc) & (fs)->fs_qfmask)
#define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
((blk) << (fs)->fs_bshift)
#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_qbmask) & (fs)->fs_bmask)
#define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
(((size) + (fs)->fs_qfmask) & (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, ip, lbn) \
(((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
: (fragroundup(fs, blkoff(fs, (ip)->i_size))))
#define dblksize(fs, dip, lbn) \
(((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
: (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)
extern int inside
[], around
[];
extern u_char
*fragtbl
[];
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