minix/usr.sbin/mkfs.mfs/v1/super.h

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#ifndef _MKFS_MFS_SUPER_H__
#define _MKFS_MFS_SUPER_H__
/* Super block table. The entry holds information about the sizes of the bit
* maps and inodes. The s_ninodes field gives the number of inodes available
* for files and directories, including the root directory. Inode 0 is
* on the disk, but not used. Thus s_ninodes = 4 means that 5 bits will be
* used in the bit map, bit 0, which is always 1 and not used, and bits 1-4
* for files and directories. The disk layout is:
*
* Item # blocks
* boot block 1
* super block 1
* inode map s_imap_blocks
* zone map s_zmap_blocks
* inodes (s_ninodes + 'inodes per block' - 1)/'inodes per block'
* unused whatever is needed to fill out the current zone
* data zones (s_zones - s_firstdatazone) << s_log_zone_size
*/
struct super_block {
uint16_t s_ninodes; /* # usable inodes on the minor device */
uint16_t s_nzones; /* total device size, including bit maps etc */
int16_t s_imap_blocks; /* # of blocks used by inode bit map */
int16_t s_zmap_blocks; /* # of blocks used by zone bit map */
uint16_t s_firstdatazone; /* number of first data zone (small) */
int16_t s_log_zone_size; /* log2 of blocks/zone */
uint32_t s_max_size; /* maximum file size on this device */
int16_t s_magic; /* magic number to recognize super-blocks */
} superblock;
/* Some members have been overidden in later versions: */
#define s_firstdatazone_old s_firstdatazone
#define s_zones s_nzones
#undef MFSFLAG_CLEAN
#undef MFSFLAG_MANDATORY_MASK
#endif