75 lines
3.0 KiB
C
75 lines
3.0 KiB
C
#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 (offset 1kB)
|
|
* 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 {
|
|
uint32_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_old; /* number of first data zone (small) */
|
|
uint16_t s_log_zone_size; /* log2 of blocks/zone */
|
|
uint16_t s_flags; /* FS state flags */
|
|
int32_t s_max_size; /* maximum file size on this device */
|
|
uint32_t s_zones; /* number of zones (replaces s_nzones in V2) */
|
|
int16_t s_magic; /* magic number to recognize super-blocks */
|
|
|
|
/* The following items are valid on disk only for V3 and above */
|
|
|
|
int16_t s_pad2; /* try to avoid compiler-dependent padding */
|
|
/* The block size in bytes. Minimum MIN_BLOCK SIZE. SECTOR_SIZE multiple.*/
|
|
uint16_t s_block_size; /* block size in bytes. */
|
|
int8_t s_disk_version; /* filesystem format sub-version */
|
|
|
|
/* The following items are only used when the super_block is in memory.
|
|
* If this ever changes, i.e. more fields after s_disk_version has to go to
|
|
* disk, update LAST_ONDISK_FIELD in servers/mfs/super.c as that controls
|
|
* which part of the struct is copied to and from disk.
|
|
*/
|
|
/* XXX padding inserted here... */
|
|
|
|
unsigned s_inodes_per_block; /* precalculated from magic number */
|
|
uint32_t s_firstdatazone; /* number of first data zone (big) */
|
|
} superblock;
|
|
|
|
/* s_flags contents; undefined flags are guaranteed to be zero on disk
|
|
* (not counting future versions of mfs setting them!)
|
|
*/
|
|
#define MFSFLAG_CLEAN (1L << 0) /* 0: dirty; 1: FS was unmounted cleanly */
|
|
|
|
/* Future compatability (or at least, graceful failure):
|
|
* if any of these bits are on, and the MFS or fsck
|
|
* implementation doesn't understand them, do not mount/fsck
|
|
* the FS.
|
|
*/
|
|
#define MFSFLAG_MANDATORY_MASK 0xff00
|
|
|
|
/* The block size should be registered on disk, even
|
|
* multiple. If V1 or V2 filesystem, this should be
|
|
* initialised to STATIC_BLOCK_SIZE.
|
|
*/
|
|
#define MFS_SUPER_BLOCK_SIZE s_block_size
|
|
|
|
/* To keep the super block on disk clean, the MFS server only read/write up to
|
|
* and including this field:
|
|
*/
|
|
#define LAST_ONDISK_FIELD s_disk_version
|
|
|
|
#endif
|