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

   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