1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
|
/* 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
/*
* 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
|
