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Lines 71-192
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| 71 |
with the |
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with the |
| 72 |
.Em super-block |
72 |
.Em super-block |
| 73 |
that is of size |
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that is of size |
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.Dv SBSIZE . |
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.Dv SBLOCKSIZE . |
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The following structure describes the super-block and is |
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The following structure describes the super-block and is |
| 76 |
from the file |
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from the file |
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.Aq Pa ufs/ffs/fs.h : |
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.Aq Pa ufs/ffs/fs.h : |
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.Bd -literal |
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.Bd -literal |
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/* |
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/* |
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* Super block for an FFS file system. |
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* Super block for an FFS filesystem. |
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*/ |
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*/ |
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struct fs { |
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struct fs { |
| 83 |
int32_t fs_firstfield; /* historic file system linked list, */ |
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int32_t fs_firstfield; /* historic filesystem linked list, */ |
| 84 |
int32_t fs_unused_1; /* used for incore super blocks */ |
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int32_t fs_unused_1; /* used for incore super blocks */ |
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ufs_daddr_t fs_sblkno; /* addr of super-block in filesys */ |
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int32_t fs_sblkno; /* offset of super-block in filesys */ |
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ufs_daddr_t fs_cblkno; /* offset of cyl-block in filesys */ |
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int32_t fs_cblkno; /* offset of cyl-block in filesys */ |
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ufs_daddr_t fs_iblkno; /* offset of inode-blocks in filesys */ |
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int32_t fs_iblkno; /* offset of inode-blocks in filesys */ |
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ufs_daddr_t fs_dblkno; /* offset of first data after cg */ |
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int32_t fs_dblkno; /* offset of first data after cg */ |
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int32_t fs_cgoffset; /* cylinder group offset in cylinder */ |
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int32_t fs_old_cgoffset; /* cylinder group offset in cylinder */ |
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int32_t fs_cgmask; /* used to calc mod fs_ntrak */ |
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int32_t fs_old_cgmask; /* used to calc mod fs_ntrak */ |
| 91 |
time_t fs_time; /* last time written */ |
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int32_t fs_old_time; /* last time written */ |
| 92 |
int32_t fs_size; /* number of blocks in fs */ |
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int32_t fs_old_size; /* number of blocks in fs */ |
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int32_t fs_dsize; /* number of data blocks in fs */ |
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int32_t fs_old_dsize; /* number of data blocks in fs */ |
| 94 |
int32_t fs_ncg; /* number of cylinder groups */ |
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int32_t fs_ncg; /* number of cylinder groups */ |
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int32_t fs_bsize; /* size of basic blocks in fs */ |
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int32_t fs_bsize; /* size of basic blocks in fs */ |
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int32_t fs_fsize; /* size of frag blocks in fs */ |
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int32_t fs_fsize; /* size of frag blocks in fs */ |
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int32_t fs_frag; /* number of frags in a block in fs */ |
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int32_t fs_frag; /* number of frags in a block in fs */ |
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/* these are configuration parameters */ |
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/* these are configuration parameters */ |
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int32_t fs_minfree; /* minimum percentage of free blocks */ |
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int32_t fs_minfree; /* minimum percentage of free blocks */ |
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int32_t fs_rotdelay; /* num of ms for optimal next block */ |
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int32_t fs_old_rotdelay; /* num of ms for optimal next block */ |
| 101 |
int32_t fs_rps; /* disk revolutions per second */ |
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int32_t fs_old_rps; /* disk revolutions per second */ |
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/* these fields can be computed from the others */ |
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/* these fields can be computed from the others */ |
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int32_t fs_bmask; /* ``blkoff'' calc of blk offsets */ |
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int32_t fs_bmask; /* ``blkoff'' calc of blk offsets */ |
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int32_t fs_fmask; /* ``fragoff'' calc of frag offsets */ |
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int32_t fs_fmask; /* ``fragoff'' calc of frag offsets */ |
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int32_t fs_bshift; /* ``lblkno'' calc of logical blkno */ |
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int32_t fs_bshift; /* ``lblkno'' calc of logical blkno */ |
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int32_t fs_fshift; /* ``numfrags'' calc number of frags */ |
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int32_t fs_fshift; /* ``numfrags'' calc number of frags */ |
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/* these are configuration parameters */ |
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/* these are configuration parameters */ |
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int32_t fs_maxcontig; /* max number of contiguous blks */ |
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int32_t fs_maxcontig; /* max number of contiguous blks */ |
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int32_t fs_maxbpg; /* max number of blks per cyl group */ |
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int32_t fs_maxbpg; /* max number of blks per cyl group */ |
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/* these fields can be computed from the others */ |
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/* these fields can be computed from the others */ |
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int32_t fs_fragshift; /* block to frag shift */ |
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int32_t fs_fragshift; /* block to frag shift */ |
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int32_t fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ |
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int32_t fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ |
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int32_t fs_sbsize; /* actual size of super block */ |
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int32_t fs_sbsize; /* actual size of super block */ |
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int32_t fs_csmask; /* csum block offset */ |
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int32_t fs_spare1[2]; /* old fs_csmask */ |
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int32_t fs_csshift; /* csum block number */ |
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/* old fs_csshift */ |
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int32_t fs_nindir; /* value of NINDIR */ |
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int32_t fs_nindir; /* value of NINDIR */ |
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int32_t fs_inopb; /* value of INOPB */ |
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int32_t fs_inopb; /* value of INOPB */ |
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int32_t fs_nspf; /* value of NSPF */ |
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int32_t fs_old_nspf; /* value of NSPF */ |
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/* yet another configuration parameter */ |
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/* yet another configuration parameter */ |
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int32_t fs_optim; /* optimization preference, see below */ |
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int32_t fs_optim; /* optimization preference, see below */ |
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/* these fields are derived from the hardware */ |
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int32_t fs_old_npsect; /* # sectors/track including spares */ |
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int32_t fs_npsect; /* # sectors/track including spares */ |
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int32_t fs_old_interleave; /* hardware sector interleave */ |
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int32_t fs_interleave; /* hardware sector interleave */ |
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int32_t fs_old_trackskew; /* sector 0 skew, per track */ |
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int32_t fs_trackskew; /* sector 0 skew, per track */ |
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int32_t fs_id[2]; /* unique filesystem id */ |
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/* fs_id takes the space of the unused fs_headswitch and fs_trkseek fields */ |
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int32_t fs_id[2]; /* unique file system id*/ |
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/* sizes determined by number of cylinder groups and their sizes */ |
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/* sizes determined by number of cylinder groups and their sizes */ |
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ufs_daddr_t fs_csaddr; /* blk addr of cyl grp summary area */ |
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int32_t fs_old_csaddr; /* blk addr of cyl grp summary area */ |
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int32_t fs_cssize; /* size of cyl grp summary area */ |
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int32_t fs_cssize; /* size of cyl grp summary area */ |
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int32_t fs_cgsize; /* cylinder group size */ |
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int32_t fs_cgsize; /* cylinder group size */ |
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/* these fields are derived from the hardware */ |
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int32_t fs_spare2; /* old fs_ntrak */ |
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int32_t fs_ntrak; /* tracks per cylinder */ |
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int32_t fs_old_nsect; /* sectors per track */ |
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int32_t fs_nsect; /* sectors per track */ |
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int32_t fs_old_spc; /* sectors per cylinder */ |
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int32_t fs_spc; /* sectors per cylinder */ |
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int32_t fs_old_ncyl; /* cylinders in filesystem */ |
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/* this comes from the disk driver partitioning */ |
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int32_t fs_old_cpg; /* cylinders per group */ |
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int32_t fs_ncyl; /* cylinders in file system */ |
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int32_t fs_ipg; /* inodes per group */ |
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/* these fields can be computed from the others */ |
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int32_t fs_fpg; /* blocks per group * fs_frag */ |
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int32_t fs_cpg; /* cylinders per group */ |
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int32_t fs_ipg; /* inodes per group */ |
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int32_t fs_fpg; /* blocks per group * fs_frag */ |
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/* this data must be re-computed after crashes */ |
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/* this data must be re-computed after crashes */ |
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struct csum fs_cstotal;/* cylinder summary information */ |
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struct csum fs_old_cstotal; /* cylinder summary information */ |
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/* these fields are cleared at mount time */ |
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/* these fields are cleared at mount time */ |
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int8_t fs_fmod; /* super block modified flag */ |
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int8_t fs_fmod; /* super block modified flag */ |
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int8_t fs_clean; /* file system is clean flag */ |
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int8_t fs_clean; /* filesystem is clean flag */ |
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int8_t fs_ronly; /* mounted read-only flag */ |
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int8_t fs_ronly; /* mounted read-only flag */ |
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int8_t fs_flags; /* currently unused flag */ |
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int8_t fs_old_flags; /* old FS_ flags */ |
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u_char fs_fsmnt[MAXMNTLEN]; /* name mounted on */ |
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u_char fs_fsmnt[MAXMNTLEN]; /* name mounted on */ |
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u_char fs_volname[MAXVOLLEN]; /* volume name */ |
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u_int64_t fs_swuid; /* system-wide uid */ |
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int32_t fs_pad; /* due to alignment of fs_swuid */ |
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/* these fields retain the current block allocation info */ |
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/* these fields retain the current block allocation info */ |
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int32_t fs_cgrotor; /* last cg searched */ |
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int32_t fs_cgrotor; /* last cg searched */ |
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struct csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */ |
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void *fs_ocsp[NOCSPTRS]; /* padding; was list of fs_cs buffers */ |
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int32_t *fs_maxcluster;/* max cluster in each cyl group */ |
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u_int8_t *fs_contigdirs; /* # of contiguously allocated dirs */ |
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int32_t fs_cpc; /* cyl per cycle in postbl */ |
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struct csum *fs_csp; /* cg summary info buffer for fs_cs */ |
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int16_t fs_opostbl[16][8]; /* old rotation block list head */ |
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int32_t *fs_maxcluster; /* max cluster in each cyl group */ |
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int32_t fs_sparecon[50]; /* reserved for future constants */ |
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u_int *fs_active; /* used by snapshots to track fs */ |
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int32_t fs_contigsumsize; /* size of cluster summary array */ |
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int32_t fs_old_cpc; /* cyl per cycle in postbl */ |
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int32_t fs_maxsymlinklen;/* max length of an internal symlink */ |
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int32_t fs_maxbsize; /* maximum blocking factor permitted */ |
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int32_t fs_inodefmt; /* format of on-disk inodes */ |
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int64_t fs_sparecon64[17]; /* old rotation block list head */ |
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u_int64_t fs_maxfilesize;/* maximum representable file size */ |
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int64_t fs_sblockloc; /* byte offset of standard superblock */ |
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int64_t fs_qbmask; /* ~fs_bmask for use with 64-bit size */ |
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struct csum_total fs_cstotal; /* cylinder summary information */ |
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int64_t fs_qfmask; /* ~fs_fmask for use with 64-bit size */ |
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ufs_time_t fs_time; /* last time written */ |
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int32_t fs_state; /* validate fs_clean field */ |
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int64_t fs_size; /* number of blocks in fs */ |
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int32_t fs_postblformat;/* format of positional layout tables */ |
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int64_t fs_dsize; /* number of data blocks in fs */ |
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int32_t fs_nrpos; /* number of rotational positions */ |
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ufs2_daddr_t fs_csaddr; /* blk addr of cyl grp summary area */ |
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int32_t fs_postbloff; /* (u_int16) rotation block list head */ |
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int64_t fs_pendingblocks; /* blocks in process of being freed */ |
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int32_t fs_rotbloff; /* (u_int8) blocks for each rotation */ |
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int32_t fs_pendinginodes; /* inodes in process of being freed */ |
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int32_t fs_magic; /* magic number */ |
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int32_t fs_snapinum[FSMAXSNAP]; /* list of snapshot inode numbers */ |
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u_int8_t fs_space[1]; /* list of blocks for each rotation */ |
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int32_t fs_avgfilesize; /* expected average file size */ |
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/* actually longer */ |
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int32_t fs_avgfpdir; /* expected # of files per directory */ |
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int32_t fs_save_cgsize; /* save real cg size to use fs_bsize */ |
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int32_t fs_sparecon32[26]; /* reserved for future constants */ |
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int32_t fs_flags; /* see FS_ flags below */ |
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int32_t fs_contigsumsize; /* size of cluster summary array */ |
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int32_t fs_maxsymlinklen; /* max length of an internal symlink */ |
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int32_t fs_old_inodefmt; /* format of on-disk inodes */ |
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u_int64_t fs_maxfilesize; /* maximum representable file size */ |
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int64_t fs_qbmask; /* ~fs_bmask for use with 64-bit size */ |
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int64_t fs_qfmask; /* ~fs_fmask for use with 64-bit size */ |
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int32_t fs_state; /* validate fs_clean field */ |
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int32_t fs_old_postblformat; /* format of positional layout tables */ |
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int32_t fs_old_nrpos; /* number of rotational positions */ |
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int32_t fs_spare5[2]; /* old fs_postbloff */ |
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/* old fs_rotbloff */ |
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int32_t fs_magic; /* magic number */ |
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}; |
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}; |
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/* |
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/* |
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* File system identification |
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* Filesystem identification |
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*/ |
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*/ |
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#define FS_MAGIC 0x011954 /* the fast file system magic number */ |
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#define FS_UFS1_MAGIC 0x011954 /* UFS1 fast filesystem magic number */ |
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#define FS_OKAY 0x7c269d38 /* superblock checksum */ |
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#define FS_UFS2_MAGIC 0x19540119 /* UFS2 fast filesystem magic number */ |
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#define FS_42INODEFMT -1 /* 4.2BSD inode format */ |
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#define FS_OKAY 0x7c269d38 /* superblock checksum */ |
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#define FS_44INODEFMT 2 /* 4.4BSD inode format */ |
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#define FS_42INODEFMT -1 /* 4.2BSD inode format */ |
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#define FS_44INODEFMT 2 /* 4.4BSD inode format */ |
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/* |
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/* |
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* Preference for optimization. |
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* Preference for optimization. |
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*/ |
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*/ |
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#define FS_OPTTIME 0 /* minimize allocation time */ |
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#define FS_OPTTIME 0 /* minimize allocation time */ |
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#define FS_OPTSPACE 1 /* minimize disk fragmentation */ |
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#define FS_OPTSPACE 1 /* minimize disk fragmentation */ |
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/* |
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* Rotational layout table format types |
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*/ |
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#define FS_42POSTBLFMT -1 /* 4.2BSD rotational table format */ |
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#define FS_DYNAMICPOSTBLFMT 1 /* dynamic rotational table format */ |
| 190 |
.Ed |
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.Ed |
| 191 |
.Pp |
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.Pp |
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Each disk drive contains some number of file systems. |
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Each disk drive contains some number of file systems. |
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Lines 275-287
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summary information is 2ms for a typical 3600 rpm drive. |
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summary information is 2ms for a typical 3600 rpm drive. |
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.Pp |
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.Pp |
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The element |
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The element |
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.Fa fs_rotdelay |
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.Fa fs_old_rotdelay |
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gives the minimum number of milliseconds to initiate |
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gives the minimum number of milliseconds to initiate |
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another disk transfer on the same cylinder. |
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another disk transfer on the same cylinder. |
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It is used in determining the rotationally optimal |
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It is used in determining the rotationally optimal |
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layout for disk blocks within a file; |
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layout for disk blocks within a file; |
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the default value for |
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the default value for |
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.Fa fs_rotdelay |
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.Fa fs_old_rotdelay |
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is 2ms. |
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is 2ms. |
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.Pp |
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.Pp |
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Each file system has a statically allocated number of inodes. |
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Each file system has a statically allocated number of inodes. |
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Lines 304-310
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must keep its size within |
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must keep its size within |
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.Dv MINBSIZE . |
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.Dv MINBSIZE . |
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Note that super-blocks are never more than size |
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Note that super-blocks are never more than size |
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.Dv SBSIZE . |
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.Dv SBLOCKSIZE . |
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.Pp |
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.Pp |
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The path name on which the file system is mounted is maintained in |
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The path name on which the file system is mounted is maintained in |
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.Fa fs_fsmnt . |
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.Fa fs_fsmnt . |
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Lines 336-342
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.Em "Super-block for a file system" : |
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.Em "Super-block for a file system" : |
| 337 |
The size of the rotational layout tables |
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The size of the rotational layout tables |
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is limited by the fact that the super-block is of size |
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is limited by the fact that the super-block is of size |
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.Dv SBSIZE . |
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.Dv SBLOCKSIZE . |
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The size of these tables is |
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The size of these tables is |
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.Em inversely |
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.Em inversely |
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proportional to the block |
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proportional to the block |