1/* vi: set sw=4 ts=4: */ 2/* 3 * jfs_dat.h --- stripped down header file which only contains the JFS 4 * on-disk data structures 5 */ 6 7#define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */ 8 9/* 10 * On-disk structures 11 */ 12 13/* 14 * Descriptor block types: 15 */ 16 17#define JFS_DESCRIPTOR_BLOCK 1 18#define JFS_COMMIT_BLOCK 2 19#define JFS_SUPERBLOCK 3 20 21/* 22 * Standard header for all descriptor blocks: 23 */ 24typedef struct journal_header_s 25{ 26 __u32 h_magic; 27 __u32 h_blocktype; 28 __u32 h_sequence; 29} journal_header_t; 30 31 32/* 33 * The block tag: used to describe a single buffer in the journal 34 */ 35typedef struct journal_block_tag_s 36{ 37 __u32 t_blocknr; /* The on-disk block number */ 38 __u32 t_flags; /* See below */ 39} journal_block_tag_t; 40 41/* Definitions for the journal tag flags word: */ 42#define JFS_FLAG_ESCAPE 1 /* on-disk block is escaped */ 43#define JFS_FLAG_SAME_UUID 2 /* block has same uuid as previous */ 44#define JFS_FLAG_DELETED 4 /* block deleted by this transaction */ 45#define JFS_FLAG_LAST_TAG 8 /* last tag in this descriptor block */ 46 47 48/* 49 * The journal superblock 50 */ 51typedef struct journal_superblock_s 52{ 53 journal_header_t s_header; 54 55 /* Static information describing the journal */ 56 __u32 s_blocksize; /* journal device blocksize */ 57 __u32 s_maxlen; /* total blocks in journal file */ 58 __u32 s_first; /* first block of log information */ 59 60 /* Dynamic information describing the current state of the log */ 61 __u32 s_sequence; /* first commit ID expected in log */ 62 __u32 s_start; /* blocknr of start of log */ 63 64} journal_superblock_t; 65