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// On-disk file system format.
// Both the kernel and user programs use this header file.
#define ROOTINO 1 // root i-number
#define BSIZE 512 // block size
// Disk layout:
// [ boot block | super block | log | inode blocks |
// free bit map | data blocks]
//
// mkfs computes the super block and builds an initial file system. The
// super block describes the disk layout:
struct superblock {
uint size; // Size of file system image (blocks)
uint nblocks; // Number of data blocks
uint ninodes; // Number of inodes.
uint nlog; // Number of log blocks
uint logstart; // Block number of first log block
uint inodestart; // Block number of first inode block
uint bmapstart; // Block number of first free map block
};
#define NDIRECT 12
#define NINDIRECT (BSIZE / sizeof(uint))
#define MAXFILE (NDIRECT + NINDIRECT)
// On-disk inode structure
struct dinode {
short type; // File type
short major; // Major device number (T_DEV only)
short minor; // Minor device number (T_DEV only)
short nlink; // Number of links to inode in file system
uint size; // Size of file (bytes)
uint addrs[NDIRECT+1]; // Data block addresses
};
// Inodes per block.
#define IPB (BSIZE / sizeof(struct dinode))
// Block containing inode i
#define IBLOCK(i, sb) ((i) / IPB + sb.inodestart)
// Bitmap bits per block
#define BPB (BSIZE*8)
// Block of free map containing bit for block b
#define BBLOCK(b, sb) (b/BPB + sb.bmapstart)
// Directory is a file containing a sequence of dirent structures.
#define DIRSIZ 14
struct dirent {
ushort inum;
char name[DIRSIZ];
};