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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