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