5 * The second extended file system magic number
7 #define EXT2_SUPER_MAGIC 0xEF53
10 * Structure of the super block
12 struct ext2_super_block
{
13 __le32 s_inodes_count
; /* Inodes count */
14 __le32 s_blocks_count
; /* Blocks count */
15 __le32 s_r_blocks_count
; /* Reserved blocks count */
16 __le32 s_free_blocks_count
; /* Free blocks count */
17 __le32 s_free_inodes_count
; /* Free inodes count */
18 __le32 s_first_data_block
; /* First Data Block */
19 __le32 s_log_block_size
; /* Block size */
20 __le32 s_log_frag_size
; /* Fragment size */
21 __le32 s_blocks_per_group
; /* # Blocks per group */
22 __le32 s_frags_per_group
; /* # Fragments per group */
23 __le32 s_inodes_per_group
; /* # Inodes per group */
24 __le32 s_mtime
; /* Mount time */
25 __le32 s_wtime
; /* Write time */
26 __le16 s_mnt_count
; /* Mount count */
27 __le16 s_max_mnt_count
; /* Maximal mount count */
28 __le16 s_magic
; /* Magic signature */
29 __le16 s_state
; /* File system state */
30 __le16 s_errors
; /* Behaviour when detecting errors */
31 __le16 s_minor_rev_level
; /* minor revision level */
32 __le32 s_lastcheck
; /* time of last check */
33 __le32 s_checkinterval
; /* max. time between checks */
34 __le32 s_creator_os
; /* OS */
35 __le32 s_rev_level
; /* Revision level */
36 __le16 s_def_resuid
; /* Default uid for reserved blocks */
37 __le16 s_def_resgid
; /* Default gid for reserved blocks */
39 * These fields are for EXT2_DYNAMIC_REV superblocks only.
41 * Note: the difference between the compatible feature set and
42 * the incompatible feature set is that if there is a bit set
43 * in the incompatible feature set that the kernel doesn't
44 * know about, it should refuse to mount the filesystem.
46 * e2fsck's requirements are more strict; if it doesn't know
47 * about a feature in either the compatible or incompatible
48 * feature set, it must abort and not try to meddle with
49 * things it doesn't understand...
51 __le32 s_first_ino
; /* First non-reserved inode */
52 __le16 s_inode_size
; /* size of inode structure */
53 __le16 s_block_group_nr
; /* block group # of this superblock */
54 __le32 s_feature_compat
; /* compatible feature set */
55 __le32 s_feature_incompat
; /* incompatible feature set */
56 __le32 s_feature_ro_compat
; /* readonly-compatible feature set */
57 __u8 s_uuid
[16]; /* 128-bit uuid for volume */
58 char s_volume_name
[16]; /* volume name */
59 char s_last_mounted
[64]; /* directory where last mounted */
60 __le32 s_algorithm_usage_bitmap
; /* For compression */
62 * Performance hints. Directory preallocation should only
63 * happen if the EXT2_COMPAT_PREALLOC flag is on.
65 __u8 s_prealloc_blocks
; /* Nr of blocks to try to preallocate */
66 __u8 s_prealloc_dir_blocks
; /* Nr to preallocate for dirs */
69 * Journaling support valid if EXT3_FEATURE_COMPAT_HAS_JOURNAL set.
71 __u8 s_journal_uuid
[16]; /* uuid of journal superblock */
72 __u32 s_journal_inum
; /* inode number of journal file */
73 __u32 s_journal_dev
; /* device number of journal file */
74 __u32 s_last_orphan
; /* start of list of inodes to delete */
75 __u32 s_hash_seed
[4]; /* HTREE hash seed */
76 __u8 s_def_hash_version
; /* Default hash version to use */
77 __u8 s_reserved_char_pad
;
78 __u16 s_reserved_word_pad
;
79 __le32 s_default_mount_opts
;
80 __le32 s_first_meta_bg
; /* First metablock block group */
81 __u32 s_reserved
[190]; /* Padding to the end of the block */
84 #endif /* __EXT2_FS_H */