1 // On-disk file system format.
2 // Both the kernel and user programs use this header file.
3
4
5 #define ROOTINO 1 // root i-number
6 #define BSIZE 1024 // block size
7
8 // 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. The
13 // super block describes the disk layout:
14 struct superblock {
15 uint magic; // Must be FSMAGIC
16 uint size; // Size of file system image (blocks)
17 uint nblocks; // Number of data blocks
18 uint ninodes; // Number of inodes.
19 uint nlog; // Number of log blocks
20 uint logstart; // Block number of first log block
21 uint inodestart; // Block number of first inode block
22 uint bmapstart; // Block number of first free map block
23 };
24
25 #define FSMAGIC 0x10203040
26
27 #define NDIRECT 12
28 #define NINDIRECT (BSIZE / sizeof(uint))
29 #define MAXFILE (NDIRECT + NINDIRECT)
30
31 // On-disk inode structure
32 struct dinode {
33 short type; // File type
34 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 system
37 uint size; // Size of file (bytes)
38 uint addrs[NDIRECT+1]; // Data block addresses
39 };
40
41 // Inodes per block.
42 #define IPB (BSIZE / sizeof(struct dinode))
43
44 // Block containing inode i
45 #define IBLOCK(i, sb) ((i) / IPB + sb.inodestart)
46
47 // Bitmap bits per block
48 #define BPB (BSIZE*8)
49
50 // Block of free map containing bit for block b
51 #define BBLOCK(b, sb) ((b)/BPB + sb.bmapstart)
52
53 // Directory is a file containing a sequence of dirent structures.
54 #define DIRSIZ 14
55
56 struct dirent {
57 ushort inum;
58 char name[DIRSIZ];
59 };
60