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comparison src/fs.h @ 0:83c23a36980d

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author Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp>
date Fri, 26 May 2017 23:11:05 +0900
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children 435bfab09924
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-1:000000000000 0:83c23a36980d
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 // Blocks 2 through sb.ninodes/IPB hold inodes.
7 // Then free bitmap blocks holding sb.size bits.
8 // Then sb.nblocks data blocks.
9 // Then sb.nlog log blocks.
10
11 #define ROOTINO 1 // root i-number
12 #define BSIZE 512 // block size
13
14 // File system super block
15 struct superblock {
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 };
21
22 #define NDIRECT 12
23 #define NINDIRECT (BSIZE / sizeof(uint))
24 #define MAXFILE (NDIRECT + NINDIRECT)
25
26 // On-disk inode structure
27 struct dinode {
28 short type; // File type
29 short major; // Major device number (T_DEV only)
30 short minor; // Minor device number (T_DEV only)
31 short nlink; // Number of links to inode in file system
32 uint size; // Size of file (bytes)
33 uint addrs[NDIRECT+1]; // Data block addresses
34 };
35
36 // Inodes per block.
37 #define IPB (BSIZE / sizeof(struct dinode))
38
39 // Block containing inode i
40 #define IBLOCK(i) ((i) / IPB + 2)
41
42 // Bitmap bits per block
43 #define BPB (BSIZE*8)
44
45 // Block containing bit for block b
46 #define BBLOCK(b, ninodes) (b/BPB + (ninodes)/IPB + 3)
47
48 // Directory is a file containing a sequence of dirent structures.
49 #define DIRSIZ 14
50
51 struct dirent {
52 ushort inum;
53 char name[DIRSIZ];
54 };
55