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| -rw-r--r-- | share/man/man5/fs.5 | 244 |
1 files changed, 132 insertions, 112 deletions
diff --git a/share/man/man5/fs.5 b/share/man/man5/fs.5 index ad59186c49f..c364a9aa2a0 100644 --- a/share/man/man5/fs.5 +++ b/share/man/man5/fs.5 @@ -1,4 +1,4 @@ -.\" $OpenBSD: fs.5,v 1.13 2004/02/24 07:17:32 jmc Exp $ +.\" $OpenBSD: fs.5,v 1.14 2004/05/26 09:42:14 jmc Exp $ .\" $NetBSD: fs.5,v 1.3 1994/11/30 19:31:17 jtc Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 @@ -43,9 +43,9 @@ .Fd #include <ufs/ufs/inode.h> .Sh DESCRIPTION The files -.Aq Pa fs.h +.Aq Pa ufs/ffs/fs.h and -.Aq Pa inode.h +.Aq Pa ufs/ufs/inode.h declare several structures and define variables and macros which are used to create and manage the underlying format of file system objects on random access devices (disks). @@ -68,90 +68,102 @@ that is of size .Dv SBSIZE . The following structure describes the super-block and is from the file -.Aq Pa ufs/fs.h : +.Aq Pa ufs/ffs/fs.h : .Bd -literal #define FS_MAGIC 0x011954 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 */ + int32_t fs_firstfield; /* historic file system linked list, */ + int32_t fs_unused_1; /* used for incore super blocks */ + int32_t fs_sblkno; /* addr of super-block in filesys */ + int32_t fs_cblkno; /* offset of cyl-block in filesys */ + int32_t fs_iblkno; /* offset of inode-blocks in filesys */ + int32_t fs_dblkno; /* offset of first data after cg */ + int32_t fs_cgoffset; /* cylinder group offset in cylinder */ + int32_t fs_cgmask; /* used to calc mod fs_ntrak */ + time_t fs_time; /* last time written */ + int32_t fs_size; /* number of blocks in fs */ + int32_t fs_dsize; /* number of data blocks in fs */ + int32_t fs_ncg; /* number of cylinder groups */ + int32_t fs_bsize; /* size of basic blocks in fs */ + int32_t fs_fsize; /* size of frag blocks in fs */ + int32_t 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 */ + int32_t fs_minfree; /* minimum percentage of free blocks */ + int32_t fs_rotdelay; /* num of ms for optimal next block */ + int32_t 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 */ + int32_t fs_bmask; /* ``blkoff'' calc of blk offsets */ + int32_t fs_fmask; /* ``fragoff'' calc of frag offsets */ + int32_t fs_bshift; /* ``lblkno'' calc of logical blkno */ + int32_t 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 */ + int32_t fs_maxcontig; /* max number of contiguous blks */ + int32_t 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 */ + int32_t fs_fragshift; /* block to frag shift */ + int32_t fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */ + int32_t fs_sbsize; /* actual size of super block */ + int32_t fs_csmask; /* csum block offset (now unused) */ + int32_t fs_csshift; /* csum block number (now unused) */ + int32_t fs_nindir; /* value of NINDIR */ + int32_t fs_inopb; /* value of INOPB */ + int32_t fs_nspf; /* value of NSPF */ /* yet another configuration parameter */ - long fs_optim; /* optimization preference, see below */ + int32_t 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 */ + int32_t fs_npsect; /* # sectors/track including spares */ + int32_t fs_interleave; /* hardware sector interleave */ + int32_t fs_trackskew; /* sector 0 skew, per track */ +/* fs_id takes the space of the unused fs_headswitch and fs_trkseek */ + int32_t fs_id[2]; /* unique filesystem 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 */ + int32_t fs_csaddr; /* blk addr of cyl grp summary area */ + int32_t fs_cssize; /* size of cyl grp summary area */ + int32_t 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 */ + int32_t fs_ntrak; /* tracks per cylinder */ + int32_t fs_nsect; /* sectors per track */ + int32_t fs_spc; /* sectors per cylinder */ /* this comes from the disk driver partitioning */ - long fs_ncyl; /* cylinders in file system */ + int32_t 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 */ + int32_t fs_cpg; /* cylinders per group */ + int32_t fs_ipg; /* inodes per group */ + int32_t fs_fpg; /* blocks per group * fs_frag */ /* this data must be re-computed after crashes */ - struct csum fs_cstotal; /* cylinder summary information */ + 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 */ + int8_t fs_fmod; /* super block modified flag */ + int8_t fs_clean; /* file system is clean flag */ + int8_t fs_ronly; /* mounted read-only flag */ + int8_t fs_flags; /* see FS_ below */ + u_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[56]; /* reserved for future constants */ - quad fs_qbmask; /* ~fs_bmask - for use with quad size */ - quad fs_qfmask; /* ~fs_fmask - for use with quad size */ - long fs_postblformat; /* format of positional layout tables */ - long fs_nrpos; /* number of rotational 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 */ + int32_t fs_cgrotor; /* last cg searched */ + void *fs_ocsp[NOCSPTRS]; /* padding; was list of fs_cs bufs */ + u_int8_t *fs_contigdirs; /* # of contiguously allocated dirs */ + struct csum *fs_csp; /* cg summary info buffer for fs_cs */ + int32_t *fs_maxcluster; /* max cluster in each cyl group */ + int32_t fs_cpc; /* cyl per cycle in postbl */ + int16_t fs_opostbl[16][8]; /* old rotation block list head */ + int32_t fs_snapinum[20];/* reserved for snapshot inode nums */ + int32_t fs_avgfilesize; /* expected average file size */ + int32_t fs_avgfpdir; /* expected # of files per directory */ + int32_t fs_sparecon[27];/* reserved for future constants */ + time_t fs_fscktime; /* last time fsck(8)ed */ + int32_t fs_contigsumsize; /* size of cluster summary array */ + int32_t fs_maxsymlinklen; /* max length of internal symlink */ + int32_t fs_inodefmt; /* format of on-disk inodes */ + u_int64_t fs_maxfilesize;/* maximum representable file size */ + int64_t fs_qbmask; /* ~fs_bmask - for use with quad size */ + int64_t fs_qfmask; /* ~fs_fmask - for use with quad size */ + int32_t fs_state; /* validate fs_clean field */ + int32_t fs_postblformat;/* format of positional layout tables */ + int32_t fs_nrpos; /* number of rotational positions */ + int32_t fs_postbloff; /* (u_int16) rotation block list head */ + int32_t fs_rotbloff; /* (u_int8) blocks for each rotation */ + int32_t fs_magic; /* magic number */ + u_int8_t fs_space[1]; /* list of blocks for each rotation */ /* actually longer */ }; .Ed @@ -191,7 +203,7 @@ 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 -.Fn blksize +.Fn blksize fs ip lbn macro. .Pp The file system records space availability at the fragment level; @@ -206,19 +218,19 @@ assumption, so we are stuck with it). Thus the root inode is 2. .Pp The -.Fa fs_minfree +.Va fs_minfree element gives the minimum acceptable percentage of file system blocks that may be free. -If the freelist drops below this level +If the freelist drops below this level, only the superuser may continue to allocate blocks. The -.Fa fs_minfree +.Va fs_minfree element may be set to 0 if no reserve of free blocks is deemed necessary, although severe performance degradations will be observed if the file system is run at greater than 95% full; thus the default value of -.Fa fs_minfree +.Va fs_minfree is 5%. .Pp Empirically the best trade-off between block fragmentation and @@ -227,43 +239,52 @@ fragmentation of 8; thus the default fragment size is an eighth of the block size. .Pp The element -.Fa fs_optim +.Va fs_optim specifies whether the file system should try to minimize the time spent -allocating blocks, or if it should attempt to minimize the space -fragmentation on the disk. +allocating blocks +.Pq Dv FS_OPTTIME , +or if it should attempt to minimize the space fragmentation on the disk +.Pq Dv FS_OPTSPACE . If the value of -.Fa fs_minfree +.Va fs_minfree (see above) is less than 5%, then the file system defaults to optimizing for space to avoid running out of full sized blocks. If the value of -.Fa fs_minfree +.Va fs_minfree is greater than or equal to 5%, fragmentation is unlikely to be problematical, and the file system defaults to optimizing for time. +.Pp +The +.Va fs_flags +element specifies how the filesystem was mounted: +.Pp +.Bl -tag -width FS_DOSOFTDEP -offset ind -compact +.It Dv FS_DOSOFTDEP +The filesystem was mounted using soft dependencies. +.It Dv FS_UNCLEAN +The filesystem was mounted uncleanly. +.El .Ss Cylinder group related limits Each cylinder keeps track of the availability of blocks at different rotational positions, so that sequential blocks can be laid out with minimum rotational latency. -With the default of 8 distinguished -rotational positions, the resolution of the -summary information is 2ms for a typical 3600 rpm drive. +With the default of 1 distinct +rotational position, the resolution of the +summary information is 16ms for a typical 3600 RPM drive. .Pp The element -.Fa fs_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 value for -.Fa fs_rotdelay -is 2ms. +.Va fs_rotdelay +was once used to tweak block layout. .Pp -Each file system has a statically allocated number of inodes. -An inode is allocated for each -.Dv NBPI -bytes of disk space. -The inode allocation strategy is extremely conservative. +Each file system has a statically allocated number of inodes, determined +by its size and the desired number of file data bytes per inode at the +time it was created. +See +.Xr newfs 8 +for details on how to set this (and other) filesystem parameters. +By default, the inode allocation strategy is extremely conservative. .Pp .Dv MINBSIZE is the smallest allowable block size. @@ -275,29 +296,24 @@ it is possible to create files of size .Dv MINBSIZE must be big enough to hold a cylinder group block, thus changes to -.Fa struct cg +.Va struct cg must keep its size within .Dv MINBSIZE . Note that super-blocks are never more than size .Dv SBSIZE . .Pp The path name on which the file system is mounted is maintained in -.Fa fs_fsmnt . +.Va fs_fsmnt . .Dv 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 -.Dv MAXCSBUFS . -For a 4096 byte block size, it is currently parameterized for a -maximum of two million cylinders. .Pp Per cylinder group information is summarized in blocks allocated from the first cylinder group's data blocks. These blocks are read in from -.Fa fs_csaddr -(size -.Fa fs_cssize ) +.Va fs_csaddr +(of size +.Va fs_cssize ) in addition to the super-block. .Pp Note that @@ -317,19 +333,21 @@ The size of the tables is increased when sector sizes are not powers of two, as this increases the number of cylinders included before the rotational pattern repeats -.Pq Fa fs_cpc . +.Pq Va fs_cpc . The size of the rotational layout tables is derived from the number of bytes remaining in -.Fa struct fs . +.Va struct fs . .Pp The number of blocks of data per cylinder group is limited because cylinder groups are at most one block. The inode and free block tables must fit into a single block after deducting space for the cylinder group structure -.Fa struct cg . +.Va struct cg . .Ss Inodes -The inode is the focus of all file activity in the +The +.Em inode +is the focus of all file activity in the .Tn UNIX file system. There is a unique inode allocated @@ -342,7 +360,9 @@ by its device/i-number pair. For further information, see the include file .Aq Pa ufs/ufs/inode.h . .Sh HISTORY -A super-block structure named filsys appeared in +A super-block structure named +.Em filsys +appeared in .At v6 . The file system described in this manual appeared in |