1 // On-disk file system format. 2 // Both the kernel and user programs use this header file. 3 4 // Block 0 is unused. 5 // Block 1 is super block. 6 // Inodes start at block 2. 7 8 #define ROOTINO 1 // root i-number 9 #define BSIZE 512 // block size 10 11 // File system super block 12 struct superblock { 13 uint size; // Size of file system image (blocks) 14 uint nblocks; // Number of data blocks 15 uint ninodes; // Number of inodes. 16 }; 17 18 #define NADDRS (NDIRECT+1) 19 #define NDIRECT 12 20 #define INDIRECT 12 21 #define NINDIRECT (BSIZE / sizeof(uint)) 22 #define MAXFILE (NDIRECT + NINDIRECT) 23 24 // On-disk inode structure 25 struct dinode { 26 short type; // File type 27 short major; // Major device number (T_DEV only) 28 short minor; // Minor device number (T_DEV only) 29 short nlink; // Number of links to inode in file system 30 uint size; // Size of file (bytes) 31 uint addrs[NADDRS]; // Data block addresses 32 }; 33 34 // Inodes per block. 35 #define IPB (BSIZE / sizeof(struct dinode)) 36 37 // Block containing inode i 38 #define IBLOCK(i) ((i) / IPB + 2) 39 40 // Bitmap bits per block 41 #define BPB (BSIZE*8) 42 43 // Block containing bit for block b 44 #define BBLOCK(b, ninodes) (b/BPB + (ninodes)/IPB + 3) 45 46 // PAGEBREAK: 10 47 // Directory is a file containing a sequence of dirent structures. 48 #define DIRSIZ 14 49 50 struct dirent { 51 ushort inum; 52 char name[DIRSIZ]; 53 }; 54 55