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diff --git a/static/unix-v10/man5/filsys.5 b/static/unix-v10/man5/filsys.5 new file mode 100644 index 00000000..baec9a38 --- /dev/null +++ b/static/unix-v10/man5/filsys.5 @@ -0,0 +1,327 @@ +.TH FILSYS 5 +.CT 2 sa +.SH NAME +filsys, flblk, ino \- format of file system volume +.SH SYNOPSIS +.B #include <sys/types.h> +.br +.B #include <sys/fblk.h> +.br +.B #include <sys/filsys.h> +.br +.B #include <sys/ino.h> +.SH DESCRIPTION +Every +file system is divided into a certain number +of blocks of 1K or 4K bytes, as determined by +the predicate +.L BITFS() +applied to the minor device number +where the file system is mounted. +Block 0 is unused and is available to contain +a bootstrap program, pack label, or other information. +.PP +Block 1 is the +`super block'. +Its layout is defined in +.LR <sys/filsys.h> : +.PP +.EX +.ta \w'#define 'u +\w'unsigned 'u +struct filsys { + unsigned short s_isize; + daddr_t s_fsize; + short s_ninode; + ino_t s_inode[NICINOD]; + char s_flock; + char s_ilock; + char s_fmod; + char s_ronly; + time_t s_time; + daddr_t s_tfree; + ino_t s_tinode; + short s_dinfo[2]; +#define s_m s_dinfo[0] +#define s_n s_dinfo[1] +#define s_cylsize s_dinfo[0] +#define s_aspace s_dinfo[1] + char s_fsmnt[14]; + ino_t s_lasti; + ino_t s_nbehind; + union { + struct { + short S_nfree; + daddr_t S_free[NICFREE]; + } R; + struct { + char S_valid; +#define BITMAP 961 + long S_bfree[BITMAP]; + } B; + struct { + char S_valid; + char S_flag; /* 1 means bitmap not in S_bfree */ + long S_bsize;/* how big the bitmap blocks are */ + struct buf * S_blk[BITMAP-1]; + } N; + } U; +}; +#define s_nfree U.R.S_nfree +#define s_free U.R.S_free +#define s_valid U.B.S_valid +#define s_bfree U.B.S_bfree +.EE +.TF s_isize +.TP +.B s_isize +The address of the first block after the i-list, +which starts in block 2. +Thus the i-list is +.LR s_isize-2 +blocks long. +.PD +.TP +.B s_fsize +The address of the first block not in the file system. +.TP +.B s_free +In a 1K file system, an array of free block numbers. +.LR s_free[0] +is the block address of the next +in a chain of blocks constituting the free list. +The layout of these blocks is defined in +.LR <sys/fblk.h> : +.EX +struct fblk { + int df_nfree; + daddr_t df_free[NICFREE]; +} +.EE +.ns +.IP +where +.L df_nfree +and +.L df_free +are exactly like +.L s_nfree +and +.L s_free. +.TP +.B s_nfree +Blocks given in +.L s_free[1] +through +.L s_free[s_nfree-1] +are available for allocation. +Blocks are allocated in LIFO fashion from this list. +If freeing would cause +the array to overflow, +it is cleared by copying into the newly freed block, +which is pushed onto the free chain. +If allocation would cause underflow, +the array is replenished from the next block on the chain. +.TP +.B s_bfree +a bit array specifying the free blocks of a 4K file system. +The bit +.LR (s_bfree[i/w]>>(i%w))&1 , +where +.I w +is the bit size of a long, +is nonzero if the +.IR i th +data block is free. If the file system is too large for the bitmap +to fit here, then it is stored at the end of the file system, and +locked into memory when the file system is mounted. The +.B N +variant of the union is used by the kernel in this case. +.TP +.B s_valid +The bitmap of a mounted file system is maintained only in main memory; +the bitmap on the medium is marked invalid by setting +.L s_valid +to zero. +Unmounting +updates the medium copy and sets +.L s_valid +to 1. +A file system with invalid bitmap may be mounted +read-only; its bitmap can be corrected by +.IR fsck (8) +or +.IR chuck (8). +.TP +.B s_inode +Array of free inode numbers. +.TP +.B s_ninode +The number of free i-numbers in the +.L s_inode +array. +Inodes are placed in the list in LIFO order. +If the list underflows, it is replenished by +searching the i-list +to obtain the numbers of free inodes. +When the list is full, +freed inodes are not recorded in +.LR s_inode . +.TP +.B s_lasti +Where the last search for free inodes ended. +.TP +.B s_nbehind +Number of free inodes before +.L s_lasti +that are not listed in +.LR s_inode . +The system will search forward for free inodes from +.L s_lasti +for more inodes unless +.L s_nbehind +is sufficiently large, in which case it will search the +i-list from the beginning. +.TP +.B s_flock +.br +.ns +.TP +.B s_ilock +Flags maintained in the core +copy of the file system +while it is mounted. +The values on disk are immaterial. +.TP +.B s_fmod +Flag to indicate that the super-block has +changed and should be copied to +the disk during the next periodic update of file +system information. +The value on disk is immaterial. +.TP +.B s_ronly +Flag for read-only file system. +The value on disk is immaterial. +.TP +.B s_time +Time of the last change to the super block. +.TP +.B s_dinfo +Disk interleave information: +.BR s_cylsize = +blocks per cylinder, +.BR s_aspace = +blocks to skip; see +.IR fsck (8). +.TP +.B s_fsmnt +Name of the file on which this file system is mounted; see +.IR fmount (2). (This field is no longer used.) +.TP +.B s_tfree +.br +.ns +.TP +.B s_tinode +Numbers of free blocks and free inodes. +Maintained for the benefit of +.IR df (1), +these values are otherwise irrelevant. +.PD +.PP +I-numbers begin at 1, and the storage for inodes +begins in block 2. +I-nodes are 128 bytes long; the first 64 bytes hold a security label. +I-node 2 is reserved for the root directory of the file +system, but no other i-number has a built-in +meaning. +Each inode represents one file. +.PP +The layout of an inode is defined in +.LR <sys/ino.h> : +.PP +.EX +struct dinode { + struct label di_label; + unsigned short di_mode; + short di_nlink; + short di_uid; + short di_gid; + off_t di_size; + char di_addr[40]; + time_t di_atime; + time_t di_mtime; + time_t di_ctime; +}; +.EE +.TF di_nlink +.TP +.B di_label +Security label; see +.IR getflab (2). +.TP +.B di_mode +The kind of file; it +is encoded as +.L st_mode field of +.IR stat (2), +and is 0 for a free inode. +.PD +.TP +.B di_nlink +The number of directory entries +(links) that refer to this inode +.TP +.B di_uid +Owner's userid. +.TP +.B di_gid +Owner's groupid. +.TP +.B size +Number of bytes in the file. +.TP +.B di_atime +Time of last access; see +.IR times (2). +.TP +.B di_mtime +Time of last modification. +.TP +.B di_ctime +Time of last change to inode or contents. +.TP +.B di_addr +For special files +.L di_addr +is the device code; see +.IR types (5). +The device codes +of block and character special files overlap. +.PD +.IP +For plain files and directories +.L di_addr +contains block numbers packed into 3 bytes each. +The first 10 numbers specify device blocks directly. +The last 3 are singly, doubly, and triply +indirect and point to blocks of 256 block pointers of type +.L daddr_t +(see +.IR types (5)). +A zero pointer indicates a `hole' +where no data has been written. +Holes read as if they contained all zeroes. +.PP +A symbolic link is, aside from mode, +a plain file whose sole content is the name of the file linked to. +.SH "SEE ALSO" +.IR chuck (8), +.IR fsck (8), +.IR icheck (8), +.IR dir (5), +.IR mount (8), +.IR stat (2), +.IR types (5), +.IR l3tol (3) + |