1 #ifndef __MFS_SUPER_H__ 2 #define __MFS_SUPER_H__ 3 4 /* Super block table. The root file system and every mounted file system 5 * has an entry here. The entry holds information about the sizes of the bit 6 * maps and inodes. The s_ninodes field gives the number of inodes available 7 * for files and directories, including the root directory. Inode 0 is 8 * on the disk, but not used. Thus s_ninodes = 4 means that 5 bits will be 9 * used in the bit map, bit 0, which is always 1 and not used, and bits 1-4 10 * for files and directories. The disk layout is: 11 * 12 * Item # blocks 13 * boot block 1 14 * super block 1 (offset 1kB) 15 * inode map s_imap_blocks 16 * zone map s_zmap_blocks 17 * inodes (s_ninodes + 'inodes per block' - 1)/'inodes per block' 18 * unused whatever is needed to fill out the current zone 19 * data zones (s_zones - s_firstdatazone) << s_log_zone_size 20 * 21 * A super_block slot is free if s_dev == NO_DEV. 22 */ 23 24 EXTERN struct super_block { 25 u32_t s_ninodes; /* # usable inodes on the minor device */ 26 zone1_t s_nzones; /* total device size, including bit maps etc */ 27 short s_imap_blocks; /* # of blocks used by inode bit map */ 28 short s_zmap_blocks; /* # of blocks used by zone bit map */ 29 zone1_t s_firstdatazone_old; /* number of first data zone (small) */ 30 short s_log_zone_size; /* log2 of blocks/zone */ 31 unsigned short s_flags; /* FS state flags */ 32 i32_t s_max_size; /* maximum file size on this device */ 33 zone_t s_zones; /* number of zones (replaces s_nzones in V2) */ 34 short s_magic; /* magic number to recognize super-blocks */ 35 36 /* The following items are valid on disk only for V3 and above */ 37 38 short s_pad2; /* try to avoid compiler-dependent padding */ 39 unsigned short s_block_size; /* block size in bytes. */ 40 char s_disk_version; /* filesystem format sub-version */ 41 42 /* The following items are only used when the super_block is in memory. 43 * If this ever changes, i.e. more fields after s_disk_version has to go to 44 * disk, update LAST_ONDISK_FIELD in super.c as that controls which part of the 45 * struct is copied to and from disk. 46 */ 47 48 /*struct inode *s_isup;*/ /* inode for root dir of mounted file sys */ 49 /*struct inode *s_imount;*/ /* inode mounted on */ 50 unsigned s_inodes_per_block; /* precalculated from magic number */ 51 zone_t s_firstdatazone; /* number of first data zone (big) */ 52 dev_t s_dev; /* whose super block is this? */ 53 int s_rd_only; /* set to 1 iff file sys mounted read only */ 54 int s_native; /* set to 1 iff not byte swapped file system */ 55 int s_version; /* file system version, zero means bad magic */ 56 int s_ndzones; /* # direct zones in an inode */ 57 int s_nindirs; /* # indirect zones per indirect block */ 58 bit_t s_isearch; /* inodes below this bit number are in use */ 59 bit_t s_zsearch; /* all zones below this bit number are in use*/ 60 } superblock; 61 62 #define IMAP 0 /* operating on the inode bit map */ 63 #define ZMAP 1 /* operating on the zone bit map */ 64 65 /* s_flags contents; undefined flags are guaranteed to be zero on disk 66 * (not counting future versions of mfs setting them!) 67 */ 68 #define MFSFLAG_CLEAN (1L << 0) /* 0: dirty; 1: FS was unmounted cleanly */ 69 70 /* Future compatability (or at least, graceful failure): 71 * if any of these bits are on, and the MFS or fsck 72 * implementation doesn't understand them, do not mount/fsck 73 * the FS. 74 */ 75 #define MFSFLAG_MANDATORY_MASK 0xff00 76 77 #endif 78 79