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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 512 // block size
7
8 // Disk layout:
9 // [ boot block | super block | log | inode blocks | free bit map | data blocks ]
10 //
11 // mkfs computes the super block and builds an initial file system. The super describes
12 // the disk layout:
13 struct superblock {
14 uint size; // Size of file system image (blocks)
15 uint nblocks; // Number of data blocks
16 uint ninodes; // Number of inodes.
17 uint nlog; // Number of log blocks
18 uint logstart; // Block number of first log block
19 uint inodestart; // Block number of first inode block
20 uint bmapstart; // Block number of first free map block
21 };
22
23 #define NDIRECT 12
24 #define NINDIRECT (BSIZE / sizeof(uint))
25 #define MAXFILE (NDIRECT + NINDIRECT)
26
27 // On-disk inode structure
28 struct dinode {
29 short type; // File type
30 short major; // Major device number (T_DEV only)
31 short minor; // Minor device number (T_DEV only)
32 short nlink; // Number of links to inode in file system
33 uint size; // Size of file (bytes)
34 uint addrs[NDIRECT+1]; // Data block addresses
35 };
36
37 // Inodes per block.
38 #define IPB (BSIZE / sizeof(struct dinode))
39
40 // Block containing inode i
41 #define IBLOCK(i, sb) ((i) / IPB + sb.inodestart)
42
43 // Bitmap bits per block
44 #define BPB (BSIZE*8)
45
46 // Block of free map containing bit for block b
47 #define BBLOCK(b, sb) (b/BPB + sb.bmapstart)
48
49 // Directory is a file containing a sequence of dirent structures.
50 #define DIRSIZ 14
51
52 struct dirent {
53 ushort inum;
54 char name[DIRSIZ];
55 };
56