64 lines
1.5 KiB
C
64 lines
1.5 KiB
C
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/* vi: set sw=4 ts=4: */
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/*
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* jfs_dat.h --- stripped down header file which only contains the JFS
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* on-disk data structures
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*/
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#define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
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/*
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* On-disk structures
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*/
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/*
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* Descriptor block types:
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*/
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#define JFS_DESCRIPTOR_BLOCK 1
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#define JFS_COMMIT_BLOCK 2
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#define JFS_SUPERBLOCK 3
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/*
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* Standard header for all descriptor blocks:
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*/
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typedef struct journal_header_s
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{
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__u32 h_magic;
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__u32 h_blocktype;
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__u32 h_sequence;
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} journal_header_t;
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/*
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* The block tag: used to describe a single buffer in the journal
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*/
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typedef struct journal_block_tag_s
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{
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__u32 t_blocknr; /* The on-disk block number */
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__u32 t_flags; /* See below */
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} journal_block_tag_t;
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/* Definitions for the journal tag flags word: */
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#define JFS_FLAG_ESCAPE 1 /* on-disk block is escaped */
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#define JFS_FLAG_SAME_UUID 2 /* block has same uuid as previous */
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#define JFS_FLAG_DELETED 4 /* block deleted by this transaction */
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#define JFS_FLAG_LAST_TAG 8 /* last tag in this descriptor block */
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/*
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* The journal superblock
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*/
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typedef struct journal_superblock_s
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{
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journal_header_t s_header;
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/* Static information describing the journal */
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__u32 s_blocksize; /* journal device blocksize */
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__u32 s_maxlen; /* total blocks in journal file */
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__u32 s_first; /* first block of log information */
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/* Dynamic information describing the current state of the log */
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__u32 s_sequence; /* first commit ID expected in log */
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__u32 s_start; /* blocknr of start of log */
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} journal_superblock_t;
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