243 lines
7.8 KiB
PHP
243 lines
7.8 KiB
PHP
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;** SUPERB.H - Super Block and Spare Block definitions
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;
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; FILESYS
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; Gregory A. Jones
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; Copyright 1988 Microsoft Corporation
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;
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; Modification history:
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; P.A. Williams 06/01/89 Added fields SPB_CPSEC and SPB_CPCNT to
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; the spare block.
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; P.A. Williams 06/05/89 Changed base and functional version no. to 1.
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;
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SEC_SUPERB equ 16 ; superblock is after 8K boot block
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SEC_SPAREB equ 17 ; spareblock is after superblock
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SEC_BOOT equ 0 ; boot sector
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;* SUPERB.INC - Super Block Definition
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;
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; The Superblock is the first block of the file system.
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; It starts at sector #4, leaving 2K for boot sectors.
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;
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; Pointer to the root directory
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; Pointer to the bit map
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; Clean pointer
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; Pointer to the bad list
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;
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RSP struc
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P dd ? ; main psector pointer
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P2 dd ? ; spare pointer
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RSP ends
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SuperB struc
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SB_SIG1 dd ? ; signature value 1
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SB_SIG2 dd ? ; signature value 2
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SB_VER db ? ; version # of filesystem structures
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SB_FVER db ? ; functional version number - the smallest/
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; oldest version of the filesystem that can
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; understand this disk - some version
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; enhancements may define fields which can be
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; ignored by earlier versions
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SB_DUMY dw ? ; free
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SB_ROOT dd ? ; Psector # of root fnode
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SB_SEC dd ? ; # of sectors on volume
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SB_BSEC dd ? ; # of bad sectors on volume
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SB_BII db (size RSP) dup (?) ; Bitmap Indirect Block
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SB_BBL db (size RSP) dup (?) ; badblock list chain #1
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SB_CDDAT dd ? ; date of last CHKDSK
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SB_DODAT dd ? ; date of last Disk Optimize
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SB_DBSIZE dd ? ; # of sectors in dirblk band
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SB_DBLOW dd ? ; first Psector in DIRBLK band
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SB_DBHIGH dd ? ; last Psector in DIRBLK band
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SB_DBMAP dd ? ; first Psector of DIRBLK band bit map. Starts
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; on a 2K boundary, 2K bytes maximum
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SB_VOLNAME db 32 dup (?) ; Volume name
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SB_SIDSEC dd ? ; sector # of first sector in SIDTAB
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; ID map is 4K - 8 contiguous sectors
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SB_FILL db 512-100 dup (?) ; fill definition out to 512 bytes
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; MUST BE ZERO
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SuperB ends
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;* SpareB - Spare Block Definitions
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;
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; SpareB contains various emergency supplies and fixup information.
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; This stuff isn't in the superblock in order for the superblock
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; to be read only and decrease the liklihood that a flakey write
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; will cause the superblock to become unreadable.
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;
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; This sector is located directly after the superblock - sector 5.
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;
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; Note that the number of spare DIRBLKs is a format option, given
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; that they all have to fit into the SpareB, giving us a max of
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; 101 of them.
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;
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; Access to the SpareB is complicated by the fact that we can't
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; access it via the cache, since the cache may be unavailable.
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; If every cache buffer is dirty, we could get a HotFix error when
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; writing the first one, which would deadlock us if we needed to
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; read this stuff via the cache. Instead, we read it directly into
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; a private buffer via RdHF.
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;
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; This means that the disk layout must be such that each cache cluster
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; that contains the SpareB or the hotfix list must not contain any
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; other writable sector, to prevent us from having a modified
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; direct-written sector overwritten by an earlier unmodified copy
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; which was in a cache block. It's ok for the SuperB to be in the
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; same cache group as the SpareB since the SuperB is RO to the filesys.
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;
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; Checksums. Done on both Super Block and the Spare Block.
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; Both checksums are stored in the Spare Block. The checksum
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; field for the Super Block (SPB_SUPERBSUM) must be set when
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; calculating the checksum for the Spare Block. The checksum
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; field for the Spare Block (SPB_SPAREBSUM) must be zero when
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; calculating the checksum for the Spare Block.
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; If both checksum fields are zero, the checksums have not been
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; calculated for the volume.
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;
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SPAREDB equ 20 ; 20 spare DIRBLKs
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SpareB struc
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SPB_SIG1 dd ? ; signature value 1
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SPB_SIG2 dd ? ; signature value 2
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SPB_FLAG db ? ; cleanliness flag
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SPB_ALIGN db 3 dup (?) ; alignment
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SPB_HFSEC dd ? ; first hotfix list P sector
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SPB_HFUSE dd ? ; # of hot fixes in effect
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SPB_HFMAX dd ? ; max size of hot fix list
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SPB_SDBCNT dd ? ; # of spare dirblks
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SPB_SDBMAX dd ? ; maximum number of spare DB values.
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SPB_CPSEC dd ? ; code page sector
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SPB_CPCNT dd ? ; number of code pages
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SPB_SUPERBSUM dd ? ; Checksum of Super Block
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SPB_SPAREBSUM dd ? ; Checksum of Spare Block
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SPB_DUMY dd 15 dup (?) ; some extra space for future use
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SPB_SPARDB dd 101 dup (?) ; Psector #s of spare dirblks
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SpareB ends
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; Super Block Signature
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SBSIG1 equ 0f995e849h ; two signatures cause we got lotsa
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SBSIG2 equ 0FA53E9C5h ; space
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SPSIG1 equ 0f9911849h ; two signatures cause we got lotsa
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SPSIG2 equ 0FA5229C5h ; space
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; Superblock Versions
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SBBASEV equ 2 ; base version
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SBBASEFV equ 2 ; base functional version
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; Spare Block Flags
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;
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SPF_DIRT equ 0001h ; file system is dirty
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SPF_SPARE equ 0002h ; spare DIRBLKs have been used
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SPF_HFUSED equ 0004h ; hot fix sectors have been used
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SPF_BADSEC equ 0008h ; bad sector, corrupt disk
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SPF_BADBM equ 0010h ; bad bitmap block
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SPF_VER equ 0080h ; file system was written by a version
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; < SB_VER, so some of the new fields
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; may have not been updated
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;* Bit maps
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;
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; PFS keeps track of free space in a series of bit maps.
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; Currently, each bit map is 2048 bytes, which covers about
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; 8 megabytes of disk space. We could rearrange these to be
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; more cylinder sensitive...
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;
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; The superblock has the address of a section of contiguous sectors
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; that contains a double word sector # for each bit map block. This
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; will be a maximum of 2048 bytes (4 sectors)
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;
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; Max # of size RAM (K) size 2nd lvl
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; bitmaps (meg) to reside bitmap
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; bitmap (bytes)
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;
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; 1 8.39 2 256
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; 2 16.78 4 512
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; 3 25.17 6 768
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; 4 33.55 8 1024
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; 5 41.94 10 1280
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; 6 50.33 12 1536
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; 7 58.72 14 1792
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; 8 67.11 16 2048
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; 9 75.50 18 2304
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; 10 83.89 20 2560
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; 15 125.83 30 3840
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; 20 167.77 40 5120
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; 30 251.66 60 7680
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; 40 335.54 80 10240
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; 50 419.43 100 12800
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; 100 838.86 200 25600
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; 200 1677.72 400 51200
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; 300 2516.58 600 76800
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; 400 3355.44 800 102400
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; 500 4194.30 1000 128000
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;
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;* Hot Fixing
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;
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; Each file system maintains a structure listing N "hot fix"
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; disk clusters of HOTFIXSIZ sectors each, each starting on
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; a multiple of HOTFIXSIZ. Whenever the file system discovers
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; that it's trying to write to a bad spot on the disk it will
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; instead select a free hot fix cluster and write there, instead.
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; The substitution will be recorded in the hot fix list, and the
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; SBF_SPARE bit will be set. The file system sill describes the
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; data as being in the bad old sectors; the disk interface will
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; do a mapping between the `believed' location and the true location.
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;
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; CHKDSK will be run as soon as possible; it will move the
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; hot fixed data from the hot fix cluster to somewhere else,
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; freeing that hot fix cluster, and adjusting the disk structure
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; to point to the new location of the data. As a result, entrys
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; on the hot fix list should be transient and few.
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;
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; The superblock contains the first sector of the hot fix list
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; which takes the following format:
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;
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; long oldsec[SB_HFMAX]; sector # of start of bad clusters
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; long newsec[SB_HFMAX]; sector # of start of subst. cluster
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; long fnode [SB_HFMAX]; fnode sector of file/directory
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; involved with bad cluster. May be
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; 0 (don't know) or invalid. The
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; repair program must verify that it
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; *is* an FNODE and must see if other
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; structures might also involve this
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; bad cluster.
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;
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; the SB_HFUSE field describes the number of these records which is
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; in use - unused ones should have oldsec[i] = 0. The list will
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; be 'dense' - no oldsec[i] will be 0 where i < SB_HFUSE.
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;
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; The sector(s) which contain the hot fix list must be contiguous
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; and may not themselves be defective.
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;
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