kernel/fs.h
62 lines
1// On-disk file system format.2// Both the kernel and user programs use this header file.345#define ROOTINO 1 // root i-number6#define BSIZE 1024 // block size78// Disk layout:9// [ boot block | super block | log | inode blocks |10// free bit map | data blocks]11//12// mkfs computes the super block and builds an initial file system. The13// super block describes the disk layout:14struct superblock {15 uint magic; // Must be FSMAGIC16 uint size; // Size of file system image (blocks)17 uint nblocks; // Number of data blocks18 uint ninodes; // Number of inodes.19 uint nlog; // Number of log blocks20 uint logstart; // Block number of first log block21 uint inodestart; // Block number of first inode block22 uint bmapstart; // Block number of first free map block23};2425#define FSMAGIC 0x102030402627#define NDIRECT 1228#define NINDIRECT (BSIZE / sizeof(uint))29#define MAXFILE (NDIRECT + NINDIRECT)3031// On-disk inode structure32struct dinode {33 short type; // File type34 short major; // Major device number (T_DEVICE only)35 short minor; // Minor device number (T_DEVICE only)36 short nlink; // Number of links to inode in file system37 uint size; // Size of file (bytes)38 uint addrs[NDIRECT+1]; // Data block addresses39};4041// Inodes per block.42#define IPB (BSIZE / sizeof(struct dinode))4344// Block containing inode i45#define IBLOCK(i, sb) ((i) / IPB + sb.inodestart)4647// Bitmap bits per block48#define BPB (BSIZE*8)4950// Block of free map containing bit for block b51#define BBLOCK(b, sb) ((b)/BPB + sb.bmapstart)5253// Directory is a file containing a sequence of dirent structures.54#define DIRSIZ 145556// The name field may have DIRSIZ characters and not end in a NUL57// character.58struct dirent {59 ushort inum;60 char name[DIRSIZ] __attribute__((nonstring));61};6263