[thirdparty/linux.git] / fs / erofs / erofs_fs.h

/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
/*
 * EROFS (Enhanced ROM File System) on-disk format definition
 *
 * Copyright (C) 2017-2018 HUAWEI, Inc.
 *             http://www.huawei.com/
 * Created by Gao Xiang <gaoxiang25@huawei.com>
 */
#ifndef __EROFS_FS_H
#define __EROFS_FS_H

#define EROFS_SUPER_OFFSET      1024

#define EROFS_FEATURE_COMPAT_SB_CHKSUM          0x00000001

/*
 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
 * be incompatible with this kernel version.
 */
#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING	0x00000001
#define EROFS_ALL_FEATURE_INCOMPAT		EROFS_FEATURE_INCOMPAT_LZ4_0PADDING

/* 128-byte erofs on-disk super block */
struct erofs_super_block {
	__le32 magic;           /* file system magic number */
	__le32 checksum;        /* crc32c(super_block) */
	__le32 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 feature_incompat;
	__u8 reserved2[44];
};

/*
 * erofs inode datalayout (i_format in on-disk inode):
 * 0 - inode plain without inline data A:
 * inode, [xattrs], ... | ... | no-holed data
 * 1 - inode VLE compression B (legacy):
 * inode, [xattrs], extents ... | ...
 * 2 - inode plain with inline data C:
 * inode, [xattrs], last_inline_data, ... | ... | no-holed data
 * 3 - inode compression D:
 * inode, [xattrs], map_header, extents ... | ...
 * 4~7 - reserved
 */
enum {
	EROFS_INODE_FLAT_PLAIN			= 0,
	EROFS_INODE_FLAT_COMPRESSION_LEGACY	= 1,
	EROFS_INODE_FLAT_INLINE			= 2,
	EROFS_INODE_FLAT_COMPRESSION		= 3,
	EROFS_INODE_DATALAYOUT_MAX
};

static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
{
	return datamode == EROFS_INODE_FLAT_COMPRESSION ||
		datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
}

/* bit definitions of inode i_advise */
#define EROFS_I_VERSION_BITS            1
#define EROFS_I_DATALAYOUT_BITS         3

#define EROFS_I_VERSION_BIT             0
#define EROFS_I_DATALAYOUT_BIT          1

/* 32-byte reduced form of an ondisk inode */
struct erofs_inode_compact {
	__le16 i_format;	/* inode format hints */

/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
	__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;

		/* for device files, used to indicate old/new device # */
		__le32 rdev;
	} i_u;
	__le32 i_ino;           /* only used for 32-bit stat compatibility */
	__le16 i_uid;
	__le16 i_gid;
	__le32 i_reserved2;
};

/* 32 bytes on-disk inode */
#define EROFS_INODE_LAYOUT_COMPACT	0
/* 64 bytes on-disk inode */
#define EROFS_INODE_LAYOUT_EXTENDED	1

/* 64-byte complete form of an ondisk inode */
struct erofs_inode_extended {
	__le16 i_format;	/* inode format hints */

/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
	__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;

		/* for device files, used to indicate old/new device # */
		__le32 rdev;
	} i_u;

	/* only used for 32-bit stat compatibility */
	__le32 i_ino;

	__le32 i_uid;
	__le32 i_gid;
	__le64 i_ctime;
	__le32 i_ctime_nsec;
	__le32 i_nlink;
	__u8   i_reserved2[16];
};

#define EROFS_MAX_SHARED_XATTRS         (128)
/* h_shared_count between 129 ... 255 are special # */
#define EROFS_SHARED_XATTR_EXTENT       (255)

/*
 * inline xattrs (n == i_xattr_icount):
 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
 *          12 bytes           /                   \
 *                            /                     \
 *                           /-----------------------\
 *                           |  erofs_xattr_entries+ |
 *                           +-----------------------+
 * inline xattrs must starts in erofs_xattr_ibody_header,
 * for read-only fs, no need to introduce h_refcount
 */
struct erofs_xattr_ibody_header {
	__le32 h_reserved;
	__u8   h_shared_count;
	__u8   h_reserved2[7];
	__le32 h_shared_xattrs[0];      /* shared xattr id array */
};

/* Name indexes */
#define EROFS_XATTR_INDEX_USER              1
#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS  2
#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
#define EROFS_XATTR_INDEX_TRUSTED           4
#define EROFS_XATTR_INDEX_LUSTRE            5
#define EROFS_XATTR_INDEX_SECURITY          6

/* xattr entry (for both inline & shared xattrs) */
struct erofs_xattr_entry {
	__u8   e_name_len;      /* length of name */
	__u8   e_name_index;    /* attribute name index */
	__le16 e_value_size;    /* size of attribute value */
	/* followed by e_name and e_value */
	char   e_name[0];       /* attribute name */
};

static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
{
	if (!i_xattr_icount)
		return 0;

	return sizeof(struct erofs_xattr_ibody_header) +
		sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
}

#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))

static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
{
	return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
				 e->e_name_len + le16_to_cpu(e->e_value_size));
}

/* available compression algorithm types (for h_algorithmtype) */
enum {
	Z_EROFS_COMPRESSION_LZ4	= 0,
	Z_EROFS_COMPRESSION_MAX
};

/*
 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
 *  e.g. for 4k logical cluster size,      4B        if compacted 2B is off;
 *                                  (4B) + 2B + (4B) if compacted 2B is on.
 */
#define Z_EROFS_ADVISE_COMPACTED_2B_BIT         0

#define Z_EROFS_ADVISE_COMPACTED_2B     (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)

struct z_erofs_map_header {
	__le32	h_reserved1;
	__le16	h_advise;
	/*
	 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
	 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
	 */
	__u8	h_algorithmtype;
	/*
	 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
	 * bit 3-4 : (physical - logical) cluster bits of head 1:
	 *       For example, if logical clustersize = 4096, 1 for 8192.
	 * bit 5-7 : (physical - logical) cluster bits of head 2.
	 */
	__u8	h_clusterbits;
};

#define Z_EROFS_VLE_LEGACY_HEADER_PADDING       8

/*
 * Fixed-sized output compression ondisk Logical Extent cluster type:
 *    0 - literal (uncompressed) cluster
 *    1 - compressed cluster (for the head logical cluster)
 *    2 - compressed cluster (for the other logical clusters)
 *
 * In detail,
 *    0 - literal (uncompressed) cluster,
 *        di_advise = 0
 *        di_clusterofs = the literal data offset of the cluster
 *        di_blkaddr = the blkaddr of the literal cluster
 *
 *    1 - compressed cluster (for the head logical cluster)
 *        di_advise = 1
 *        di_clusterofs = the decompressed data offset of the cluster
 *        di_blkaddr = the blkaddr of the compressed cluster
 *
 *    2 - compressed cluster (for the other logical clusters)
 *        di_advise = 2
 *        di_clusterofs =
 *           the decompressed data offset in its own head cluster
 *        di_u.delta[0] = distance to its corresponding head cluster
 *        di_u.delta[1] = distance to its corresponding tail cluster
 *                (di_advise could be 0, 1 or 2)
 */
enum {
	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN		= 0,
	Z_EROFS_VLE_CLUSTER_TYPE_HEAD		= 1,
	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD	= 2,
	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED	= 3,
	Z_EROFS_VLE_CLUSTER_TYPE_MAX
};

#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS        2
#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT         0

struct z_erofs_vle_decompressed_index {
	__le16 di_advise;
	/* where to decompress in the head cluster */
	__le16 di_clusterofs;

	union {
		/* for the head cluster */
		__le32 blkaddr;
		/*
		 * for the rest clusters
		 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
		 * [0] - pointing to the head cluster
		 * [1] - pointing to the tail cluster
		 */
		__le16 delta[2];
	} di_u;
};

#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
	(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
	 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)

/* dirent sorts in alphabet order, thus we can do binary search */
struct erofs_dirent {
	__le64 nid;     /* node number */
	__le16 nameoff; /* start offset of file name */
	__u8 file_type; /* file type */
	__u8 reserved;  /* reserved */
} __packed;

/*
 * EROFS file types should match generic FT_* types and
 * it seems no need to add BUILD_BUG_ONs since potential
 * unmatchness will break other fses as well...
 */

#define EROFS_NAME_LEN      255

/* check the EROFS on-disk layout strictly at compile time */
static inline void erofs_check_ondisk_layout_definitions(void)
{
	BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
	BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
	BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
	BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
	BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
	BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
	BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
	BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);

	BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
		     Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
}

#endif
Commit	Line	Data
29b24f6c GX	1	/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
29b24f6c GX	2	/*
ea559e7b GX	3	* EROFS (Enhanced ROM File System) on-disk format definition
ea559e7b GX	4	*
aea1286d GX	5	* Copyright (C) 2017-2018 HUAWEI, Inc.
	6	* http://www.huawei.com/
	7	* Created by Gao Xiang <gaoxiang25@huawei.com>
aea1286d GX	8	*/
	9	#ifndef __EROFS_FS_H
	10	#define __EROFS_FS_H
	11
aea1286d GX	12	#define EROFS_SUPER_OFFSET 1024
aea1286d GX	13
b858a484 PS	14	#define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
b858a484 PS	15
5efe5137	16	/*
426a9308 GX	17	* Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
426a9308 GX	18	* be incompatible with this kernel version.
5efe5137	19	*/
426a9308 GX	20	#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001
426a9308 GX	21	#define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING
5efe5137	22
4b66eb51	23	/* 128-byte erofs on-disk super block */
aea1286d	24	struct erofs_super_block {
4b66eb51 GX	25	__le32 magic; /* file system magic number */
4b66eb51 GX	26	__le32 checksum; /* crc32c(super_block) */
426a9308	27	__le32 feature_compat;
4b66eb51 GX	28	__u8 blkszbits; /* support block_size == PAGE_SIZE only */
	29	__u8 reserved;
	30
	31	__le16 root_nid; /* nid of root directory */
	32	__le64 inos; /* total valid ino # (== f_files - f_favail) */
	33
	34	__le64 build_time; /* inode v1 time derivation */
	35	__le32 build_time_nsec; /* inode v1 time derivation in nano scale */
	36	__le32 blocks; /* used for statfs */
	37	__le32 meta_blkaddr; /* start block address of metadata area */
	38	__le32 xattr_blkaddr; /* start block address of shared xattr area */
	39	__u8 uuid[16]; /* 128-bit uuid for volume */
	40	__u8 volume_name[16]; /* volume name */
426a9308	41	__le32 feature_incompat;
4b66eb51	42	__u8 reserved2[44];
ed34aa4a	43	};
aea1286d	44
aea1286d	45	/*
ea559e7b	46	* erofs inode datalayout (i_format in on-disk inode):
aea1286d GX	47	* 0 - inode plain without inline data A:
aea1286d GX	48	* inode, [xattrs], ... \| ... \| no-holed data
ec8c2442	49	* 1 - inode VLE compression B (legacy):
aea1286d GX	50	* inode, [xattrs], extents ... \| ...
	51	* 2 - inode plain with inline data C:
	52	* inode, [xattrs], last_inline_data, ... \| ... \| no-holed data
ec8c2442 GX	53	* 3 - inode compression D:
	54	* inode, [xattrs], map_header, extents ... \| ...
	55	* 4~7 - reserved
aea1286d GX	56	*/
aea1286d GX	57	enum {
60a49ba8 GX	58	EROFS_INODE_FLAT_PLAIN = 0,
	59	EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1,
	60	EROFS_INODE_FLAT_INLINE = 2,
	61	EROFS_INODE_FLAT_COMPRESSION = 3,
8a765682	62	EROFS_INODE_DATALAYOUT_MAX
aea1286d	63	};
ccd9c19c	64
3d2969fa	65	static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
ec8c2442	66	{
c39747f7 GX	67	return datamode == EROFS_INODE_FLAT_COMPRESSION \|\|
c39747f7 GX	68	datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
ec8c2442 GX	69	}
ec8c2442 GX	70
ccd9c19c	71	/* bit definitions of inode i_advise */
aea1286d	72	#define EROFS_I_VERSION_BITS 1
8a765682	73	#define EROFS_I_DATALAYOUT_BITS 3
aea1286d GX	74
aea1286d GX	75	#define EROFS_I_VERSION_BIT 0
8a765682	76	#define EROFS_I_DATALAYOUT_BIT 1
aea1286d	77
4b66eb51	78	/* 32-byte reduced form of an ondisk inode */
8a765682 GX	79	struct erofs_inode_compact {
8a765682 GX	80	__le16 i_format; /* inode format hints */
aea1286d GX	81
aea1286d GX	82	/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
4b66eb51 GX	83	__le16 i_xattr_icount;
	84	__le16 i_mode;
	85	__le16 i_nlink;
	86	__le32 i_size;
	87	__le32 i_reserved;
	88	union {
aea1286d GX	89	/* file total compressed blocks for data mapping 1 */
	90	__le32 compressed_blocks;
	91	__le32 raw_blkaddr;
	92
	93	/* for device files, used to indicate old/new device # */
	94	__le32 rdev;
ed34aa4a	95	} i_u;
4b66eb51 GX	96	__le32 i_ino; /* only used for 32-bit stat compatibility */
	97	__le16 i_uid;
	98	__le16 i_gid;
	99	__le32 i_reserved2;
ed34aa4a	100	};
aea1286d GX	101
aea1286d GX	102	/* 32 bytes on-disk inode */
8a765682	103	#define EROFS_INODE_LAYOUT_COMPACT 0
aea1286d	104	/* 64 bytes on-disk inode */
8a765682	105	#define EROFS_INODE_LAYOUT_EXTENDED 1
aea1286d	106
4b66eb51	107	/* 64-byte complete form of an ondisk inode */
8a765682 GX	108	struct erofs_inode_extended {
8a765682 GX	109	__le16 i_format; /* inode format hints */
cead56f8 GX	110
cead56f8 GX	111	/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
4b66eb51 GX	112	__le16 i_xattr_icount;
	113	__le16 i_mode;
	114	__le16 i_reserved;
	115	__le64 i_size;
	116	union {
aea1286d GX	117	/* file total compressed blocks for data mapping 1 */
	118	__le32 compressed_blocks;
	119	__le32 raw_blkaddr;
	120
	121	/* for device files, used to indicate old/new device # */
	122	__le32 rdev;
ed34aa4a	123	} i_u;
aea1286d GX	124
aea1286d GX	125	/* only used for 32-bit stat compatibility */
4b66eb51 GX	126	__le32 i_ino;
	127
	128	__le32 i_uid;
	129	__le32 i_gid;
	130	__le64 i_ctime;
	131	__le32 i_ctime_nsec;
	132	__le32 i_nlink;
	133	__u8 i_reserved2[16];
ed34aa4a	134	};
aea1286d GX	135
	136	#define EROFS_MAX_SHARED_XATTRS (128)
	137	/* h_shared_count between 129 ... 255 are special # */
	138	#define EROFS_SHARED_XATTR_EXTENT (255)
	139
	140	/*
	141	* inline xattrs (n == i_xattr_icount):
	142	* erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
	143	* 12 bytes / \
	144	* / \
	145	* /-----------------------\
	146	* \| erofs_xattr_entries+ \|
	147	* +-----------------------+
	148	* inline xattrs must starts in erofs_xattr_ibody_header,
	149	* for read-only fs, no need to introduce h_refcount
	150	*/
	151	struct erofs_xattr_ibody_header {
cead56f8	152	__le32 h_reserved;
aea1286d	153	__u8 h_shared_count;
cead56f8	154	__u8 h_reserved2[7];
aea1286d	155	__le32 h_shared_xattrs[0]; /* shared xattr id array */
ed34aa4a	156	};
aea1286d GX	157
	158	/* Name indexes */
	159	#define EROFS_XATTR_INDEX_USER 1
	160	#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2
	161	#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
	162	#define EROFS_XATTR_INDEX_TRUSTED 4
	163	#define EROFS_XATTR_INDEX_LUSTRE 5
	164	#define EROFS_XATTR_INDEX_SECURITY 6
	165
	166	/* xattr entry (for both inline & shared xattrs) */
	167	struct erofs_xattr_entry {
	168	__u8 e_name_len; /* length of name */
	169	__u8 e_name_index; /* attribute name index */
	170	__le16 e_value_size; /* size of attribute value */
	171	/* followed by e_name and e_value */
	172	char e_name[0]; /* attribute name */
ed34aa4a	173	};
aea1286d	174
b6796abd GX	175	static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
	176	{
	177	if (!i_xattr_icount)
	178	return 0;
	179
	180	return sizeof(struct erofs_xattr_ibody_header) +
	181	sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
	182	}
aea1286d GX	183
aea1286d GX	184	#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
b6796abd GX	185
	186	static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
	187	{
	188	return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
	189	e->e_name_len + le16_to_cpu(e->e_value_size));
	190	}
aea1286d	191
ea559e7b	192	/* available compression algorithm types (for h_algorithmtype) */
ec8c2442	193	enum {
60a49ba8	194	Z_EROFS_COMPRESSION_LZ4 = 0,
ec8c2442 GX	195	Z_EROFS_COMPRESSION_MAX
	196	};
	197
	198	/*
	199	* bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
	200	* e.g. for 4k logical cluster size, 4B if compacted 2B is off;
	201	* (4B) + 2B + (4B) if compacted 2B is on.
	202	*/
	203	#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0
	204
	205	#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
	206
	207	struct z_erofs_map_header {
	208	__le32 h_reserved1;
	209	__le16 h_advise;
	210	/*
	211	* bit 0-3 : algorithm type of head 1 (logical cluster type 01);
	212	* bit 4-7 : algorithm type of head 2 (logical cluster type 11).
	213	*/
	214	__u8 h_algorithmtype;
	215	/*
	216	* bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
	217	* bit 3-4 : (physical - logical) cluster bits of head 1:
	218	* For example, if logical clustersize = 4096, 1 for 8192.
	219	* bit 5-7 : (physical - logical) cluster bits of head 2.
	220	*/
	221	__u8 h_clusterbits;
	222	};
	223
	224	#define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8
aea1286d GX	225
aea1286d GX	226	/*
ea559e7b	227	* Fixed-sized output compression ondisk Logical Extent cluster type:
aea1286d GX	228	* 0 - literal (uncompressed) cluster
	229	* 1 - compressed cluster (for the head logical cluster)
	230	* 2 - compressed cluster (for the other logical clusters)
	231	*
	232	* In detail,
	233	* 0 - literal (uncompressed) cluster,
	234	* di_advise = 0
	235	* di_clusterofs = the literal data offset of the cluster
	236	* di_blkaddr = the blkaddr of the literal cluster
	237	*
	238	* 1 - compressed cluster (for the head logical cluster)
	239	* di_advise = 1
	240	* di_clusterofs = the decompressed data offset of the cluster
	241	* di_blkaddr = the blkaddr of the compressed cluster
	242	*
	243	* 2 - compressed cluster (for the other logical clusters)
	244	* di_advise = 2
	245	* di_clusterofs =
	246	* the decompressed data offset in its own head cluster
	247	* di_u.delta[0] = distance to its corresponding head cluster
	248	* di_u.delta[1] = distance to its corresponding tail cluster
	249	* (di_advise could be 0, 1 or 2)
	250	*/
99691b46	251	enum {
60a49ba8 GX	252	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0,
	253	Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1,
	254	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2,
	255	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3,
99691b46 GX	256	Z_EROFS_VLE_CLUSTER_TYPE_MAX
	257	};
	258
aea1286d GX	259	#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2
	260	#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0
	261
	262	struct z_erofs_vle_decompressed_index {
	263	__le16 di_advise;
	264	/* where to decompress in the head cluster */
	265	__le16 di_clusterofs;
	266
	267	union {
	268	/* for the head cluster */
	269	__le32 blkaddr;
	270	/*
	271	* for the rest clusters
	272	* eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
	273	* [0] - pointing to the head cluster
	274	* [1] - pointing to the tail cluster
	275	*/
	276	__le16 delta[2];
ed34aa4a GX	277	} di_u;
ed34aa4a GX	278	};
aea1286d	279
ec8c2442 GX	280	#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
	281	(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
	282	sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
aea1286d GX	283
	284	/* dirent sorts in alphabet order, thus we can do binary search */
	285	struct erofs_dirent {
4b66eb51 GX	286	__le64 nid; /* node number */
	287	__le16 nameoff; /* start offset of file name */
	288	__u8 file_type; /* file type */
	289	__u8 reserved; /* reserved */
aea1286d GX	290	} __packed;
aea1286d GX	291
1d819c54 GX	292	/*
	293	* EROFS file types should match generic FT_* types and
	294	* it seems no need to add BUILD_BUG_ONs since potential
	295	* unmatchness will break other fses as well...
	296	*/
aea1286d GX	297
	298	#define EROFS_NAME_LEN 255
	299
	300	/* check the EROFS on-disk layout strictly at compile time */
	301	static inline void erofs_check_ondisk_layout_definitions(void)
	302	{
	303	BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
8a765682 GX	304	BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
8a765682 GX	305	BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
aea1286d GX	306	BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
aea1286d GX	307	BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
ec8c2442	308	BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
aea1286d GX	309	BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
aea1286d GX	310	BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
99691b46 GX	311
	312	BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
	313	Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
aea1286d GX	314	}
	315
	316	#endif
	317