1 #ifndef _MKFS_MFS_SUPER_H__ 2 #define _MKFS_MFS_SUPER_H__ 3 4 /* Super block table. The entry holds information about the sizes of the bit 5 * maps and inodes. The s_ninodes field gives the number of inodes available 6 * for files and directories, including the root directory. Inode 0 is 7 * on the disk, but not used. Thus s_ninodes = 4 means that 5 bits will be 8 * used in the bit map, bit 0, which is always 1 and not used, and bits 1-4 9 * for files and directories. The disk layout is: 10 * 11 * Item # blocks 12 * boot block 1 13 * super block 1 14 * inode map s_imap_blocks 15 * zone map s_zmap_blocks 16 * inodes (s_ninodes + 'inodes per block' - 1)/'inodes per block' 17 * unused whatever is needed to fill out the current zone 18 * data zones (s_zones - s_firstdatazone) << s_log_zone_size 19 */ 20 21 struct super_block { 22 uint16_t s_ninodes; /* # usable inodes on the minor device */ 23 uint16_t s_nzones; /* total device size, including bit maps etc */ 24 int16_t s_imap_blocks; /* # of blocks used by inode bit map */ 25 int16_t s_zmap_blocks; /* # of blocks used by zone bit map */ 26 uint16_t s_firstdatazone; /* number of first data zone (small) */ 27 int16_t s_log_zone_size; /* log2 of blocks/zone */ 28 uint32_t s_max_size; /* maximum file size on this device */ 29 int16_t s_magic; /* magic number to recognize super-blocks */ 30 } superblock; 31 32 /* Some members have been overidden in later versions: */ 33 #define s_firstdatazone_old s_firstdatazone 34 #define s_zones s_nzones 35 36 #undef MFSFLAG_CLEAN 37 #undef MFSFLAG_MANDATORY_MASK 38 39 #endif 40