| 1 | /*
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| 2 | * jfs_dat.h --- stripped down header file which only contains the JFS
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| 3 | * on-disk data structures
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| 4 | */
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| 5 |
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| 6 | #define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
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| 7 |
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| 8 | /*
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| 9 | * On-disk structures
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| 10 | */
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| 11 |
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| 12 | /*
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| 13 | * Descriptor block types:
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| 14 | */
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| 15 |
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| 16 | #define JFS_DESCRIPTOR_BLOCK 1
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| 17 | #define JFS_COMMIT_BLOCK 2
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| 18 | #define JFS_SUPERBLOCK 3
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| 19 |
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| 20 | /*
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| 21 | * Standard header for all descriptor blocks:
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| 22 | */
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| 23 | typedef struct journal_header_s
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| 24 | {
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| 25 | __u32 h_magic;
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| 26 | __u32 h_blocktype;
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| 27 | __u32 h_sequence;
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| 28 | } journal_header_t;
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| 29 |
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| 30 |
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| 31 | /*
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| 32 | * The block tag: used to describe a single buffer in the journal
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| 33 | */
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| 34 | typedef struct journal_block_tag_s
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| 35 | {
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| 36 | __u32 t_blocknr; /* The on-disk block number */
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| 37 | __u32 t_flags; /* See below */
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| 38 | } journal_block_tag_t;
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| 39 |
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| 40 | /* Definitions for the journal tag flags word: */
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| 41 | #define JFS_FLAG_ESCAPE 1 /* on-disk block is escaped */
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| 42 | #define JFS_FLAG_SAME_UUID 2 /* block has same uuid as previous */
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| 43 | #define JFS_FLAG_DELETED 4 /* block deleted by this transaction */
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| 44 | #define JFS_FLAG_LAST_TAG 8 /* last tag in this descriptor block */
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| 45 |
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| 46 |
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| 47 | /*
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| 48 | * The journal superblock
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| 49 | */
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| 50 | typedef struct journal_superblock_s
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| 51 | {
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| 52 | journal_header_t s_header;
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| 53 |
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| 54 | /* Static information describing the journal */
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| 55 | __u32 s_blocksize; /* journal device blocksize */
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| 56 | __u32 s_maxlen; /* total blocks in journal file */
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| 57 | __u32 s_first; /* first block of log information */
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| 58 |
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| 59 | /* Dynamic information describing the current state of the log */
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| 60 | __u32 s_sequence; /* first commit ID expected in log */
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| 61 | __u32 s_start; /* blocknr of start of log */
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| 62 |
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| 63 | } journal_superblock_t;
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| 64 |
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