/* Copyright (c) 1981 Regents of the University of California */
-/* fs.h 1.9 %G% */
+/* fs.h 4.2 82/06/14 */
/*
* Each disk drive contains some number of file systems.
* super-block data does not change, so the copies need not be
* referenced further unless disaster strikes.
*
- * For file system fs and a cylinder group number cg:
- * [BBLOCK] Boot sector and bad block information
- * [SBLOCK] Super-block
- * [CBLOCK(fs)] Cylinder group block
- * [IBLOCK(fs)..IBLOCK(fs)+fs.fs_ipg/INOPB(fs))
- * Inode blocks
- * [IBLOCK(fs)+fs.fs_ipg/INOPB(fs)..fs.fs_fpg/fs.fs_frag)
- * Data blocks
- * The beginning of data blocks for cg in fs is also given by
- * the ``cgdmin(cg,fs)'' macro.
+ * 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 boot and super blocks are given in absolute disk addresses.
+ * The first boot and super blocks are given in absolute disk addresses.
*/
-#define BBLOCK ((daddr_t)(0 * (MAXBSIZE / DEV_BSIZE)))
-#define SBLOCK ((daddr_t)(1 * (MAXBSIZE / DEV_BSIZE)))
-/*
- * The cylinder group and inode blocks are given in file system
- * addresses, and hence must be converted to disk addresses by
- * the ``fsbtodb(fs, bno)'' macro.
- */
-#define CBLOCK(fs) ((daddr_t)(dbtofsb(fs, 2 * (MAXBSIZE / DEV_BSIZE))))
-#define IBLOCK(fs) ((daddr_t)(CBLOCK(fs) + (fs)->fs_frag))
+#define BBSIZE 8192
+#define SBSIZE 8192
+#define BBLOCK ((daddr_t)(0))
+#define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
/*
* Addresses stored in inodes are capable of addressing fragments
* The file system records space availability at the fragment level;
* to determine block availability, aligned fragments are examined.
*
+ * The root inode is the root of the file system.
+ * Inode 0 can't be used for normal purposes and
+ * historically bad blocks were linked to inode 1,
+ * thus the root inode is 2. (inode 1 is no longer used for
+ * this purpose, however numerous dump tapes make this
+ * assumption, so we are stuck with it)
+ * The lost+found directory is given the next available
+ * inode when it is created by ``mkfs''.
+ */
+#define ROOTINO ((ino_t)2) /* i number of all roots */
+#define LOSTFOUNDINO (ROOTINO + 1)
+
+/*
+ * MINFREE gives the minimum acceptable percentage of file system
+ * blocks which may be free. If the freelist drops below this level
+ * only the superuser may continue to allocate blocks. This may
+ * be set to 0 if no reserve of free blocks is deemed necessary,
+ * however severe performance degredations will be observed if the
+ * file system is run at greater than 90% full; thus the default
+ * value of fs_minfree is 10%.
+ *
+ * Empirically the best trade-off between block fragmentation and
+ * overall disk utilization at a loading of 90% comes with a
+ * fragmentation of 4, thus the default fragment size is a fourth
+ * of the block size.
+ */
+#define MINFREE 10
+#define DESFRAG 4
+
+/*
+ * Under current technology, most 300MB disks have 32 sectors and
+ * 16 tracks, thus these are the defaults used for fs_nsect and
+ * fs_ntrak respectively.
+ */
+#define DFLNSECT 32
+#define DFLNTRAK 16
+
+/*
+ * Cylinder group related limits.
+ *
* For each cylinder we keep track of the availability of blocks at different
* rotational positions, so that we can lay out the data to be picked
* up with minimum rotational latency. NRPOS is the number of rotational
* positions which we distinguish. With NRPOS 8 the resolution of our
* summary information is 2ms for a typical 3600 rpm drive.
+ *
+ * ROTDELAY gives the minimum number of milliseconds to initiate
+ * another disk transfer on the same cylinder. It is used in
+ * determining the rotationally optimal layout for disk blocks
+ * within a file; the default of fs_rotdelay is 2ms.
*/
-#define NRPOS 8 /* number distinct rotational positions */
-
-/*
- * Information per cylinder group 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
- * super block.
- * N.B. sizeof(struct csum) must be a power of two in order for
- * the ``fs_cs'' macro to work (see below).
- */
-struct csum {
- 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 */
-};
+#define NRPOS 8 /* number distinct rotational positions */
+#define ROTDELAY 2
/*
* Each file system has a number of inodes statically allocated.
- * We allocate one inode slot per NBPI data bytes, expecting this
+ * We allocate one inode slot per NBPI bytes, expecting this
* to be far more than we will ever need.
+ *
+ * MAXIPG bounds the number of inodes per cylinder group, and
+ * is needed only to keep the structure simpler by having the
+ * only a single variable size element (the free bit map).
+ *
+ * N.B.: MAXIPG must be a multiple of INOPB(fs).
*/
-#define NBPI 2048
+#define NBPI 2048
+#define MAXIPG 2048 /* max number inodes/cyl group */
/*
* MINBSIZE is the smallest allowable block size.
#define MINBSIZE 4096
#define DESCPG 16 /* desired fs_cpg */
#define MAXCPG 32 /* maximum fs_cpg */
-
+
/*
- * Super block for a file system.
+ * 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.
+ */
+#define MAXMNTLEN 512
+#define MAXCSBUFS 32
+
+/*
+ * 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
+ * super block.
*
- * The super block is nominally located at disk block SBLOCK.
- * Inode 0 can't be used for normal purposes,
- * historically bad blocks were linked to inode 1,
- * thus the root inode is 2. (inode 1 is no longer used for
- * this purpose, however numerous dump tapes make this
- * assumption, so we are stuck with it)
+ * N.B. sizeof(struct csum) must be a power of two in order for
+ * the ``fs_cs'' macro to work (see below).
*/
-#define ROOTINO ((ino_t)2) /* i number of all roots */
+struct csum {
+ 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 */
+};
-#define FS_MAGIC 0x110854
+/*
+ * Super block for a file system.
+ */
+#define FS_MAGIC 0x011954
struct fs
{
- long fs_magic; /* magic number */
- daddr_t fs_sblkno; /* offset of super-block in filesys */
+ 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_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 */
- short fs_minfree; /* minimum percentage of free blocks */
- short fs_rotdelay; /* num of ms for optimal next block */
+ 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 */
+ 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 */
+ long fs_sparecon[16]; /* 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 */
- short fs_ntrak; /* tracks per cylinder */
- short fs_nsect; /* sectors per track */
+ 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 */
- short fs_cpg; /* cylinders per group */
- short fs_ipg; /* inodes per group */
+ 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_fsmnt[34]; /* name mounted on */
+ 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[NBUF]; /* list of fs_cs info buffers */
- short fs_postbl[NRPOS]; /* head of blocks for each rotation */
- short fs_rotbl[1]; /* list of blocks for each rotation */
+ 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 */
};
/*
- * convert cylinder group to base address of its global summary info.
+ * 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) \
[(indx) % ((fs)->fs_bsize / sizeof(struct csum))]
/*
- * Cylinder group macros to locate things in cylinder groups.
+ * 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)
*/
-
-/* cylinder group to disk block at very beginning */
-#define cgbase(c,fs) ((daddr_t)((fs)->fs_fpg*(c)))
-
-/* cylinder group to spare super block address */
-#define cgsblock(c,fs) \
- (cgbase(c,fs) + dbtofsb(fs, SBLOCK))
-
-/* convert cylinder group to index of its cg block */
-#define cgtod(c,fs) \
- (cgbase(c,fs) + CBLOCK(fs))
-
-/* give address of first inode block in cylinder group */
-#define cgimin(c,fs) \
- (cgbase(c,fs) + IBLOCK(fs))
-
-/* give address of first data block in cylinder group */
-#define cgdmin(c,fs) (cgimin(c,fs) + (fs)->fs_ipg / INOPF(fs))
-
-/* turn inode number into cylinder group number */
-#define itog(x,fs) ((x)/(fs)->fs_ipg)
-
-/* turn inode number into file system block address */
-#define itod(x,fs) ((daddr_t)(cgimin(itog(x,fs),fs)+(fs)->fs_frag*((x)%(fs)->fs_ipg/INOPB(fs))))
-
-/* turn inode number into file system block offset */
-#define itoo(x,fs) ((x)%INOPB(fs))
-
-/* give cylinder group number for a file system block */
-#define dtog(d,fs) ((d)/(fs)->fs_fpg)
-
-/* give cylinder group block number for a file system block */
-#define dtogd(d,fs) ((d)%(fs)->fs_fpg)
+#define MAXBPC (SBSIZE - sizeof (struct fs))
/*
- * Cylinder group related limits.
+ * Cylinder group block for a file system.
*/
-
-/*
- * MAXIPG bounds the number of inodes per cylinder group, and
- * is needed only to keep the structure simpler by having the
- * only a single variable size element (the free bit map).
- *
- * N.B.: MAXIPG must be a multiple of INOPB.
- */
-#define MAXIPG 2048 /* max number inodes/cyl group */
-
-/*
- * 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) \
- (NBBY*((fs)->fs_bsize-(sizeof (struct cg)))/(fs)->fs_frag)
-
-#define CG_MAGIC 0x092752
+#define CG_MAGIC 0x090255
struct cg {
- long cg_magic; /* magic number */
+ 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 */
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 */
char cg_free[1]; /* free block map */
/* actually longer */
};
-#define cgsize(fp) (sizeof (struct cg) + ((fp)->fs_fpg+NBBY-1)/NBBY)
+
+/*
+ * 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) \
+ (NBBY * ((fs)->fs_bsize - (sizeof (struct cg))) / (fs)->fs_frag)
+
+/*
+ * 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_fsize / DEV_BSIZE))
+#define dbtofsb(fs, b) ((b) / ((fs)->fs_fsize / DEV_BSIZE))
+
+/*
+ * 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)) + \
+ (x) % (fs)->fs_ipg / INOPB(fs) * (fs)->fs_frag))
+
+/*
+ * 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_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)
+
+/*
+ * 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_bsize) \
+ ? (fs)->fs_bsize \
+ : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
+#define dblksize(fs, dip, lbn) \
+ (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) * (fs)->fs_bsize) \
+ ? (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_bsize / DEV_BSIZE)
+#define NSPF(fs) ((fs)->fs_fsize / DEV_BSIZE)
+
+/*
+ * INOPB is the number of inodes in a secondary storage block.
+ */
+#define INOPB(fs) ((fs)->fs_bsize / sizeof (struct dinode))
+#define INOPF(fs) ((fs)->fs_fsize / sizeof (struct dinode))
+
+/*
+ * NINDIR is the number of indirects in a file system block.
+ */
+#define NINDIR(fs) ((fs)->fs_bsize / sizeof (daddr_t))
#ifdef KERNEL
struct fs *getfs();
+struct fs *mountfs();
#endif