49fe5d1617
* restored the zone>block stuff * generalized the support for more-than-1-block bitmaps to also deal with big inodes maps in small blocks * improved pexit() to printf-like syntax; also replaced pexit() with err() or errx() where there are no reference to proto lines * unified the allocation of blocks to all use alloc_block() instead of raw malloc half of the time * removed the V2_ d2_ etc. prefixes which are obscure and obsolete While here, also * used new-form definitions, and closer to KNF style in general * used often-built-ins such as mem* or strncpy where relevant * pruned a fair amount of constants which are irrelevant Thanks to Thomas V. and Lionel who did a good amount of work with the cross-compilation stuff and made that change to be much smoother.
75 lines
3 KiB
C
75 lines
3 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 (offset 1kB)
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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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uint32_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_old; /* number of first data zone (small) */
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uint16_t s_log_zone_size; /* log2 of blocks/zone */
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uint16_t s_flags; /* FS state flags */
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int32_t s_max_size; /* maximum file size on this device */
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uint32_t s_zones; /* number of zones (replaces s_nzones in V2) */
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int16_t s_magic; /* magic number to recognize super-blocks */
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/* The following items are valid on disk only for V3 and above */
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int16_t s_pad2; /* try to avoid compiler-dependent padding */
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/* The block size in bytes. Minimum MIN_BLOCK SIZE. SECTOR_SIZE multiple.*/
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uint16_t s_block_size; /* block size in bytes. */
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int8_t s_disk_version; /* filesystem format sub-version */
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/* The following items are only used when the super_block is in memory.
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* If this ever changes, i.e. more fields after s_disk_version has to go to
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* disk, update LAST_ONDISK_FIELD in servers/mfs/super.c as that controls
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* which part of the struct is copied to and from disk.
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*/
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/* XXX padding inserted here... */
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unsigned s_inodes_per_block; /* precalculated from magic number */
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uint32_t s_firstdatazone; /* number of first data zone (big) */
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} superblock;
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/* s_flags contents; undefined flags are guaranteed to be zero on disk
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* (not counting future versions of mfs setting them!)
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*/
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#define MFSFLAG_CLEAN (1L << 0) /* 0: dirty; 1: FS was unmounted cleanly */
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/* Future compatability (or at least, graceful failure):
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* if any of these bits are on, and the MFS or fsck
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* implementation doesn't understand them, do not mount/fsck
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* the FS.
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*/
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#define MFSFLAG_MANDATORY_MASK 0xff00
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/* The block size should be registered on disk, even
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* multiple. If V1 or V2 filesystem, this should be
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* initialised to STATIC_BLOCK_SIZE.
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*/
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#define MFS_SUPER_BLOCK_SIZE s_block_size
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/* To keep the super block on disk clean, the MFS server only read/write up to
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* and including this field:
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*/
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#define LAST_ONDISK_FIELD s_disk_version
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#endif
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