1 /* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
2 /*
3 * EROFS (Enhanced ROM File System) on-disk format definition
4 *
5 * Copyright (C) 2017-2018 HUAWEI, Inc.
6 * http://www.huawei.com/
7 * Copyright (C) 2021, Alibaba Cloud
8 */
9 #ifndef __EROFS_FS_H
10 #define __EROFS_FS_H
11
12 #define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2
13 #define EROFS_SUPER_OFFSET 1024
14
15 #define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
16 #define EROFS_FEATURE_COMPAT_MTIME 0x00000002
17
18 /*
19 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
20 * be incompatible with this kernel version.
21 */
22 #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001
23 #define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002
24 #define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002
25 #define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004
26 #define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008
27 #define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010
28 #define EROFS_ALL_FEATURE_INCOMPAT \
29 (EROFS_FEATURE_INCOMPAT_LZ4_0PADDING | \
30 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \
31 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \
32 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \
33 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \
34 EROFS_FEATURE_INCOMPAT_ZTAILPACKING)
35
36 #define EROFS_SB_EXTSLOT_SIZE 16
37
38 struct erofs_deviceslot {
39 union {
40 u8 uuid[16]; /* used for device manager later */
41 u8 userdata[64]; /* digest(sha256), etc. */
42 } u;
43 __le32 blocks; /* total fs blocks of this device */
44 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */
45 u8 reserved[56];
46 };
47 #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot)
48
49 /* erofs on-disk super block (currently 128 bytes) */
50 struct erofs_super_block {
51 __le32 magic; /* file system magic number */
52 __le32 checksum; /* crc32c(super_block) */
53 __le32 feature_compat;
54 __u8 blkszbits; /* support block_size == PAGE_SIZE only */
55 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
56
57 __le16 root_nid; /* nid of root directory */
58 __le64 inos; /* total valid ino # (== f_files - f_favail) */
59
60 __le64 build_time; /* inode v1 time derivation */
61 __le32 build_time_nsec; /* inode v1 time derivation in nano scale */
62 __le32 blocks; /* used for statfs */
63 __le32 meta_blkaddr; /* start block address of metadata area */
64 __le32 xattr_blkaddr; /* start block address of shared xattr area */
65 __u8 uuid[16]; /* 128-bit uuid for volume */
66 __u8 volume_name[16]; /* volume name */
67 __le32 feature_incompat;
68 union {
69 /* bitmap for available compression algorithms */
70 __le16 available_compr_algs;
71 /* customized sliding window size instead of 64k by default */
72 __le16 lz4_max_distance;
73 } __packed u1;
74 __le16 extra_devices; /* # of devices besides the primary device */
75 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */
76 __u8 reserved2[38];
77 };
78
79 /*
80 * erofs inode datalayout (i_format in on-disk inode):
81 * 0 - inode plain without inline data A:
82 * inode, [xattrs], ... | ... | no-holed data
83 * 1 - inode VLE compression B (legacy):
84 * inode, [xattrs], extents ... | ...
85 * 2 - inode plain with inline data C:
86 * inode, [xattrs], last_inline_data, ... | ... | no-holed data
87 * 3 - inode compression D:
88 * inode, [xattrs], map_header, extents ... | ...
89 * 4 - inode chunk-based E:
90 * inode, [xattrs], chunk indexes ... | ...
91 * 5~7 - reserved
92 */
93 enum {
94 EROFS_INODE_FLAT_PLAIN = 0,
95 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1,
96 EROFS_INODE_FLAT_INLINE = 2,
97 EROFS_INODE_FLAT_COMPRESSION = 3,
98 EROFS_INODE_CHUNK_BASED = 4,
99 EROFS_INODE_DATALAYOUT_MAX
100 };
101
erofs_inode_is_data_compressed(unsigned int datamode)102 static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
103 {
104 return datamode == EROFS_INODE_FLAT_COMPRESSION ||
105 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
106 }
107
108 /* bit definitions of inode i_advise */
109 #define EROFS_I_VERSION_BITS 1
110 #define EROFS_I_DATALAYOUT_BITS 3
111
112 #define EROFS_I_VERSION_BIT 0
113 #define EROFS_I_DATALAYOUT_BIT 1
114
115 #define EROFS_I_ALL \
116 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1)
117
118 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */
119 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F
120 /* with chunk indexes or just a 4-byte blkaddr array */
121 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020
122
123 #define EROFS_CHUNK_FORMAT_ALL \
124 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES)
125
126 struct erofs_inode_chunk_info {
127 __le16 format; /* chunk blkbits, etc. */
128 __le16 reserved;
129 };
130
131 /* 32-byte reduced form of an ondisk inode */
132 struct erofs_inode_compact {
133 __le16 i_format; /* inode format hints */
134
135 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
136 __le16 i_xattr_icount;
137 __le16 i_mode;
138 __le16 i_nlink;
139 __le32 i_size;
140 __le32 i_reserved;
141 union {
142 /* file total compressed blocks for data mapping 1 */
143 __le32 compressed_blocks;
144 __le32 raw_blkaddr;
145
146 /* for device files, used to indicate old/new device # */
147 __le32 rdev;
148
149 /* for chunk-based files, it contains the summary info */
150 struct erofs_inode_chunk_info c;
151 } i_u;
152 __le32 i_ino; /* only used for 32-bit stat compatibility */
153 __le16 i_uid;
154 __le16 i_gid;
155 __le32 i_reserved2;
156 };
157
158 /* 32 bytes on-disk inode */
159 #define EROFS_INODE_LAYOUT_COMPACT 0
160 /* 64 bytes on-disk inode */
161 #define EROFS_INODE_LAYOUT_EXTENDED 1
162
163 /* 64-byte complete form of an ondisk inode */
164 struct erofs_inode_extended {
165 __le16 i_format; /* inode format hints */
166
167 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
168 __le16 i_xattr_icount;
169 __le16 i_mode;
170 __le16 i_reserved;
171 __le64 i_size;
172 union {
173 /* file total compressed blocks for data mapping 1 */
174 __le32 compressed_blocks;
175 __le32 raw_blkaddr;
176
177 /* for device files, used to indicate old/new device # */
178 __le32 rdev;
179
180 /* for chunk-based files, it contains the summary info */
181 struct erofs_inode_chunk_info c;
182 } i_u;
183
184 /* only used for 32-bit stat compatibility */
185 __le32 i_ino;
186
187 __le32 i_uid;
188 __le32 i_gid;
189 __le64 i_mtime;
190 __le32 i_mtime_nsec;
191 __le32 i_nlink;
192 __u8 i_reserved2[16];
193 };
194
195 #define EROFS_MAX_SHARED_XATTRS (128)
196 /* h_shared_count between 129 ... 255 are special # */
197 #define EROFS_SHARED_XATTR_EXTENT (255)
198
199 /*
200 * inline xattrs (n == i_xattr_icount):
201 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
202 * 12 bytes / \
203 * / \
204 * /-----------------------\
205 * | erofs_xattr_entries+ |
206 * +-----------------------+
207 * inline xattrs must starts in erofs_xattr_ibody_header,
208 * for read-only fs, no need to introduce h_refcount
209 */
210 struct erofs_xattr_ibody_header {
211 __le32 h_reserved;
212 __u8 h_shared_count;
213 __u8 h_reserved2[7];
214 __le32 h_shared_xattrs[0]; /* shared xattr id array */
215 };
216
217 /* Name indexes */
218 #define EROFS_XATTR_INDEX_USER 1
219 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2
220 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
221 #define EROFS_XATTR_INDEX_TRUSTED 4
222 #define EROFS_XATTR_INDEX_LUSTRE 5
223 #define EROFS_XATTR_INDEX_SECURITY 6
224
225 /* xattr entry (for both inline & shared xattrs) */
226 struct erofs_xattr_entry {
227 __u8 e_name_len; /* length of name */
228 __u8 e_name_index; /* attribute name index */
229 __le16 e_value_size; /* size of attribute value */
230 /* followed by e_name and e_value */
231 char e_name[0]; /* attribute name */
232 };
233
erofs_xattr_ibody_size(__le16 i_xattr_icount)234 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
235 {
236 if (!i_xattr_icount)
237 return 0;
238
239 return sizeof(struct erofs_xattr_ibody_header) +
240 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
241 }
242
243 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
244
erofs_xattr_entry_size(struct erofs_xattr_entry * e)245 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
246 {
247 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
248 e->e_name_len + le16_to_cpu(e->e_value_size));
249 }
250
251 /* represent a zeroed chunk (hole) */
252 #define EROFS_NULL_ADDR -1
253
254 /* 4-byte block address array */
255 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32)
256
257 /* 8-byte inode chunk indexes */
258 struct erofs_inode_chunk_index {
259 __le16 advise; /* always 0, don't care for now */
260 __le16 device_id; /* back-end storage id (with bits masked) */
261 __le32 blkaddr; /* start block address of this inode chunk */
262 };
263
264 /* maximum supported size of a physical compression cluster */
265 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024)
266
267 /* available compression algorithm types (for h_algorithmtype) */
268 enum {
269 Z_EROFS_COMPRESSION_LZ4 = 0,
270 Z_EROFS_COMPRESSION_LZMA = 1,
271 Z_EROFS_COMPRESSION_MAX
272 };
273 #define Z_EROFS_ALL_COMPR_ALGS (1 << (Z_EROFS_COMPRESSION_MAX - 1))
274
275 /* 14 bytes (+ length field = 16 bytes) */
276 struct z_erofs_lz4_cfgs {
277 __le16 max_distance;
278 __le16 max_pclusterblks;
279 u8 reserved[10];
280 } __packed;
281
282 /* 14 bytes (+ length field = 16 bytes) */
283 struct z_erofs_lzma_cfgs {
284 __le32 dict_size;
285 __le16 format;
286 u8 reserved[8];
287 } __packed;
288 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE)
289
290 /*
291 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
292 * e.g. for 4k logical cluster size, 4B if compacted 2B is off;
293 * (4B) + 2B + (4B) if compacted 2B is on.
294 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
295 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
296 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on)
297 */
298 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
299 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
300 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004
301 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008
302
303 struct z_erofs_map_header {
304 __le16 h_reserved1;
305 /* record the size of tailpacking data */
306 __le16 h_idata_size;
307 __le16 h_advise;
308 /*
309 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
310 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
311 */
312 __u8 h_algorithmtype;
313 /*
314 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
315 * bit 3-7 : reserved.
316 */
317 __u8 h_clusterbits;
318 };
319
320 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8
321
322 /*
323 * Fixed-sized output compression ondisk Logical Extent cluster type:
324 * 0 - literal (uncompressed) cluster
325 * 1 - compressed cluster (for the head logical cluster)
326 * 2 - compressed cluster (for the other logical clusters)
327 *
328 * In detail,
329 * 0 - literal (uncompressed) cluster,
330 * di_advise = 0
331 * di_clusterofs = the literal data offset of the cluster
332 * di_blkaddr = the blkaddr of the literal cluster
333 *
334 * 1 - compressed cluster (for the head logical cluster)
335 * di_advise = 1
336 * di_clusterofs = the decompressed data offset of the cluster
337 * di_blkaddr = the blkaddr of the compressed cluster
338 *
339 * 2 - compressed cluster (for the other logical clusters)
340 * di_advise = 2
341 * di_clusterofs =
342 * the decompressed data offset in its own head cluster
343 * di_u.delta[0] = distance to its corresponding head cluster
344 * di_u.delta[1] = distance to its corresponding tail cluster
345 * (di_advise could be 0, 1 or 2)
346 */
347 enum {
348 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0,
349 Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1,
350 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2,
351 Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3,
352 Z_EROFS_VLE_CLUSTER_TYPE_MAX
353 };
354
355 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2
356 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0
357
358 /*
359 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
360 * compressed block count of a compressed extent (in logical clusters, aka.
361 * block count of a pcluster).
362 */
363 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11)
364
365 struct z_erofs_vle_decompressed_index {
366 __le16 di_advise;
367 /* where to decompress in the head cluster */
368 __le16 di_clusterofs;
369
370 union {
371 /* for the head cluster */
372 __le32 blkaddr;
373 /*
374 * for the rest clusters
375 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
376 * [0] - pointing to the head cluster
377 * [1] - pointing to the tail cluster
378 */
379 __le16 delta[2];
380 } di_u;
381 };
382
383 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
384 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
385 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
386
387 #define Z_EROFS_VLE_EXTENT_ALIGN(size) round_up(size, \
388 sizeof(struct z_erofs_vle_decompressed_index))
389
390 /* dirent sorts in alphabet order, thus we can do binary search */
391 struct erofs_dirent {
392 __le64 nid; /* node number */
393 __le16 nameoff; /* start offset of file name */
394 __u8 file_type; /* file type */
395 __u8 reserved; /* reserved */
396 } __packed;
397
398 /* file types used in inode_info->flags */
399 enum {
400 EROFS_FT_UNKNOWN,
401 EROFS_FT_REG_FILE,
402 EROFS_FT_DIR,
403 EROFS_FT_CHRDEV,
404 EROFS_FT_BLKDEV,
405 EROFS_FT_FIFO,
406 EROFS_FT_SOCK,
407 EROFS_FT_SYMLINK,
408 EROFS_FT_MAX
409 };
410
411 #define EROFS_NAME_LEN 255
412
413 /* check the EROFS on-disk layout strictly at compile time */
erofs_check_ondisk_layout_definitions(void)414 static inline void erofs_check_ondisk_layout_definitions(void)
415 {
416 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
417 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
418 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
419 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
420 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
421 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4);
422 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8);
423 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
424 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
425 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
426 /* keep in sync between 2 index structures for better extendibility */
427 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) !=
428 sizeof(struct z_erofs_vle_decompressed_index));
429 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
430
431 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
432 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
433 }
434
435 #endif
436