/* Super block table. The root file system and every mounted file system * has an entry here. 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 + 1 + INODES_PER_BLOCK - 1)/INODES_PER_BLOCK * unused whatever is needed to fill out the current zone * data zones (s_nzones - s_firstdatazone) << s_log_zone_size * * A super_block slot is free if s_dev == NO_DEV. */ EXTERN struct super_block { ino_t s_ninodes; /* # usable inodes on the minor device */ zone_nr s_nzones; /* total device size, including bit maps etc */ unshort s_imap_blocks; /* # of blocks used by inode bit map */ unshort s_zmap_blocks; /* # of blocks used by zone bit map */ zone_nr s_firstdatazone; /* number of first data zone */ short int s_log_zone_size; /* log2 of blocks/zone */ off_t s_max_size; /* maximum file size on this device */ short s_magic; /* magic number to recognize super-blocks */ /* The following items are only used when the super_block is in memory. */ struct buf *s_imap[I_MAP_SLOTS]; /* pointers to the in-core inode bit map */ struct buf *s_zmap[ZMAP_SLOTS]; /* pointers to the in-core zone bit map */ dev_t s_dev; /* whose super block is this? */ struct inode *s_isup; /* inode for root dir of mounted file sys */ struct inode *s_imount; /* inode mounted on */ time_t s_time; /* time of last update */ char s_rd_only; /* set to 1 iff file sys mounted read only */ char s_dirt; /* CLEAN or DIRTY */ } super_block[NR_SUPERS]; #define NIL_SUPER (struct super_block *) 0