1 /* vi: set sw=4 ts=4: */
3 * jfs_dat.h --- stripped down header file which only contains the JFS
4 * on-disk data structures
7 #define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
14 * Descriptor block types:
17 #define JFS_DESCRIPTOR_BLOCK 1
18 #define JFS_COMMIT_BLOCK 2
19 #define JFS_SUPERBLOCK 3
22 * Standard header for all descriptor blocks:
24 typedef struct journal_header_s
33 * The block tag: used to describe a single buffer in the journal
35 typedef struct journal_block_tag_s
37 __u32 t_blocknr
; /* The on-disk block number */
38 __u32 t_flags
; /* See below */
39 } journal_block_tag_t
;
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 */
49 * The journal superblock
51 typedef struct journal_superblock_s
53 journal_header_t s_header
;
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 */
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 } journal_superblock_t
;