@@ -17,27 +17,28 @@
#define EROFS_REQUIREMENT_LZ4_0PADDING 0x00000001
#define EROFS_ALL_REQUIREMENTS EROFS_REQUIREMENT_LZ4_0PADDING
+/* 128-byte erofs on-disk super block */
struct erofs_super_block {
-/* 0 */__le32 magic; /* in the little endian */
-/* 4 */__le32 checksum; /* crc32c(super_block) */
-/* 8 */__le32 features; /* (aka. feature_compat) */
-/* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only */
-/* 13 */__u8 reserved;
-
-/* 14 */__le16 root_nid;
-/* 16 */__le64 inos; /* total valid ino # (== f_files - f_favail) */
-
-/* 24 */__le64 build_time; /* inode v1 time derivation */
-/* 32 */__le32 build_time_nsec;
-/* 36 */__le32 blocks; /* used for statfs */
-/* 40 */__le32 meta_blkaddr;
-/* 44 */__le32 xattr_blkaddr;
-/* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */
-/* 64 */__u8 volume_name[16]; /* volume name */
-/* 80 */__le32 requirements; /* (aka. feature_incompat) */
-
-/* 84 */__u8 reserved2[44];
-} __packed; /* 128 bytes */
+ __le32 magic; /* file system magic number */
+ __le32 checksum; /* crc32c(super_block) */
+ __le32 features; /* (aka. feature_compat) */
+ __u8 blkszbits; /* support block_size == PAGE_SIZE only */
+ __u8 reserved;
+
+ __le16 root_nid; /* nid of root directory */
+ __le64 inos; /* total valid ino # (== f_files - f_favail) */
+
+ __le64 build_time; /* inode v1 time derivation */
+ __le32 build_time_nsec; /* inode v1 time derivation in nano scale */
+ __le32 blocks; /* used for statfs */
+ __le32 meta_blkaddr; /* start block address of metadata area */
+ __le32 xattr_blkaddr; /* start block address of shared xattr area */
+ __u8 uuid[16]; /* 128-bit uuid for volume */
+ __u8 volume_name[16]; /* volume name */
+ __le32 requirements; /* (aka. feature_incompat) */
+
+ __u8 reserved2[44];
+} __packed;
/*
* erofs inode data mapping:
@@ -73,16 +74,17 @@ static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
#define EROFS_I_VERSION_BIT 0
#define EROFS_I_DATA_MAPPING_BIT 1
+/* 32-byte reduced form of an ondisk inode */
struct erofs_inode_v1 {
-/* 0 */__le16 i_advise;
+ __le16 i_advise; /* inode hints */
/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
-/* 2 */__le16 i_xattr_icount;
-/* 4 */__le16 i_mode;
-/* 6 */__le16 i_nlink;
-/* 8 */__le32 i_size;
-/* 12 */__le32 i_reserved;
-/* 16 */union {
+ __le16 i_xattr_icount;
+ __le16 i_mode;
+ __le16 i_nlink;
+ __le32 i_size;
+ __le32 i_reserved;
+ union {
/* file total compressed blocks for data mapping 1 */
__le32 compressed_blocks;
__le32 raw_blkaddr;
@@ -90,10 +92,10 @@ struct erofs_inode_v1 {
/* for device files, used to indicate old/new device # */
__le32 rdev;
} i_u __packed;
-/* 20 */__le32 i_ino; /* only used for 32-bit stat compatibility */
-/* 24 */__le16 i_uid;
-/* 26 */__le16 i_gid;
-/* 28 */__le32 i_reserved2;
+ __le32 i_ino; /* only used for 32-bit stat compatibility */
+ __le16 i_uid;
+ __le16 i_gid;
+ __le32 i_reserved2;
} __packed;
/* 32 bytes on-disk inode */
@@ -101,15 +103,16 @@ struct erofs_inode_v1 {
/* 64 bytes on-disk inode */
#define EROFS_INODE_LAYOUT_V2 1
+/* 64-byte complete form of an ondisk inode */
struct erofs_inode_v2 {
-/* 0 */__le16 i_advise;
+ __le16 i_advise; /* inode hints */
/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
-/* 2 */__le16 i_xattr_icount;
-/* 4 */__le16 i_mode;
-/* 6 */__le16 i_reserved;
-/* 8 */__le64 i_size;
-/* 16 */union {
+ __le16 i_xattr_icount;
+ __le16 i_mode;
+ __le16 i_reserved;
+ __le64 i_size;
+ union {
/* file total compressed blocks for data mapping 1 */
__le32 compressed_blocks;
__le32 raw_blkaddr;
@@ -119,15 +122,15 @@ struct erofs_inode_v2 {
} i_u __packed;
/* only used for 32-bit stat compatibility */
-/* 20 */__le32 i_ino;
-
-/* 24 */__le32 i_uid;
-/* 28 */__le32 i_gid;
-/* 32 */__le64 i_ctime;
-/* 40 */__le32 i_ctime_nsec;
-/* 44 */__le32 i_nlink;
-/* 48 */__u8 i_reserved2[16];
-} __packed; /* 64 bytes */
+ __le32 i_ino;
+
+ __le32 i_uid;
+ __le32 i_gid;
+ __le64 i_ctime;
+ __le32 i_ctime_nsec;
+ __le32 i_nlink;
+ __u8 i_reserved2[16];
+} __packed;
#define EROFS_MAX_SHARED_XATTRS (128)
/* h_shared_count between 129 ... 255 are special # */
@@ -264,7 +267,7 @@ struct z_erofs_vle_decompressed_index {
* [1] - pointing to the tail cluster
*/
__le16 delta[2];
- } di_u __packed; /* 8 bytes */
+ } di_u __packed;
} __packed;
#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
@@ -273,10 +276,10 @@ struct z_erofs_vle_decompressed_index {
/* dirent sorts in alphabet order, thus we can do binary search */
struct erofs_dirent {
- __le64 nid; /* 0, node number */
- __le16 nameoff; /* 8, start offset of file name */
- __u8 file_type; /* 10, file type */
- __u8 reserved; /* 11, reserved */
+ __le64 nid; /* node number */
+ __le16 nameoff; /* start offset of file name */
+ __u8 file_type; /* file type */
+ __u8 reserved; /* reserved */
} __packed;
/*