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 * https://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_OFFSET 1024
13
14 #define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
15 #define EROFS_FEATURE_COMPAT_MTIME 0x00000002
16 #define EROFS_FEATURE_COMPAT_XATTR_FILTER 0x00000004
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_ZERO_PADDING 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_COMPR_HEAD2 0x00000008
28 #define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010
29 #define EROFS_FEATURE_INCOMPAT_FRAGMENTS 0x00000020
30 #define EROFS_FEATURE_INCOMPAT_DEDUPE 0x00000020
31 #define EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES 0x00000040
32 #define EROFS_ALL_FEATURE_INCOMPAT \
33 (EROFS_FEATURE_INCOMPAT_ZERO_PADDING | \
34 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \
35 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \
36 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \
37 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \
38 EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 | \
39 EROFS_FEATURE_INCOMPAT_ZTAILPACKING | \
40 EROFS_FEATURE_INCOMPAT_FRAGMENTS | \
41 EROFS_FEATURE_INCOMPAT_DEDUPE | \
42 EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES)
43
44 #define EROFS_SB_EXTSLOT_SIZE 16
45
46 struct erofs_deviceslot {
47 u8 tag[64]; /* digest(sha256), etc. */
48 __le32 blocks; /* total fs blocks of this device */
49 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */
50 u8 reserved[56];
51 };
52 #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot)
53
54 /* erofs on-disk super block (currently 128 bytes) */
55 struct erofs_super_block {
56 __le32 magic; /* file system magic number */
57 __le32 checksum; /* crc32c(super_block) */
58 __le32 feature_compat;
59 __u8 blkszbits; /* filesystem block size in bit shift */
60 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
61
62 __le16 root_nid; /* nid of root directory */
63 __le64 inos; /* total valid ino # (== f_files - f_favail) */
64
65 __le64 build_time; /* compact inode time derivation */
66 __le32 build_time_nsec; /* compact inode time derivation in ns scale */
67 __le32 blocks; /* used for statfs */
68 __le32 meta_blkaddr; /* start block address of metadata area */
69 __le32 xattr_blkaddr; /* start block address of shared xattr area */
70 __u8 uuid[16]; /* 128-bit uuid for volume */
71 __u8 volume_name[16]; /* volume name */
72 __le32 feature_incompat;
73 union {
74 /* bitmap for available compression algorithms */
75 __le16 available_compr_algs;
76 /* customized sliding window size instead of 64k by default */
77 __le16 lz4_max_distance;
78 } __packed u1;
79 __le16 extra_devices; /* # of devices besides the primary device */
80 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */
81 __u8 dirblkbits; /* directory block size in bit shift */
82 __u8 xattr_prefix_count; /* # of long xattr name prefixes */
83 __le32 xattr_prefix_start; /* start of long xattr prefixes */
84 __le64 packed_nid; /* nid of the special packed inode */
85 __u8 xattr_filter_reserved; /* reserved for xattr name filter */
86 __u8 reserved2[23];
87 };
88
89 /*
90 * EROFS inode datalayout (i_format in on-disk inode):
91 * 0 - uncompressed flat inode without tail-packing inline data:
92 * 1 - compressed inode with non-compact indexes:
93 * 2 - uncompressed flat inode with tail-packing inline data:
94 * 3 - compressed inode with compact indexes:
95 * 4 - chunk-based inode with (optional) multi-device support:
96 * 5~7 - reserved
97 */
98 enum {
99 EROFS_INODE_FLAT_PLAIN = 0,
100 EROFS_INODE_COMPRESSED_FULL = 1,
101 EROFS_INODE_FLAT_INLINE = 2,
102 EROFS_INODE_COMPRESSED_COMPACT = 3,
103 EROFS_INODE_CHUNK_BASED = 4,
104 EROFS_INODE_DATALAYOUT_MAX
105 };
106
107 static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
108 {
109 return datamode == EROFS_INODE_COMPRESSED_COMPACT ||
110 datamode == EROFS_INODE_COMPRESSED_FULL;
111 }
112
113 /* bit definitions of inode i_format */
114 #define EROFS_I_VERSION_MASK 0x01
115 #define EROFS_I_DATALAYOUT_MASK 0x07
116
117 #define EROFS_I_VERSION_BIT 0
118 #define EROFS_I_DATALAYOUT_BIT 1
119 #define EROFS_I_ALL_BIT 4
120
121 #define EROFS_I_ALL ((1 << EROFS_I_ALL_BIT) - 1)
122
123 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */
124 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F
125 /* with chunk indexes or just a 4-byte blkaddr array */
126 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020
127
128 #define EROFS_CHUNK_FORMAT_ALL \
129 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES)
130
131 /* 32-byte on-disk inode */
132 #define EROFS_INODE_LAYOUT_COMPACT 0
133 /* 64-byte on-disk inode */
134 #define EROFS_INODE_LAYOUT_EXTENDED 1
135
136 struct erofs_inode_chunk_info {
137 __le16 format; /* chunk blkbits, etc. */
138 __le16 reserved;
139 };
140
141 union erofs_inode_i_u {
142 /* total compressed blocks for compressed inodes */
143 __le32 compressed_blocks;
144
145 /* block address for uncompressed flat inodes */
146 __le32 raw_blkaddr;
147
148 /* for device files, used to indicate old/new device # */
149 __le32 rdev;
150
151 /* for chunk-based files, it contains the summary info */
152 struct erofs_inode_chunk_info c;
153 };
154
155 /* 32-byte reduced form of an ondisk inode */
156 struct erofs_inode_compact {
157 __le16 i_format; /* inode format hints */
158
159 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
160 __le16 i_xattr_icount;
161 __le16 i_mode;
162 __le16 i_nlink;
163 __le32 i_size;
164 __le32 i_reserved;
165 union erofs_inode_i_u i_u;
166
167 __le32 i_ino; /* only used for 32-bit stat compatibility */
168 __le16 i_uid;
169 __le16 i_gid;
170 __le32 i_reserved2;
171 };
172
173 /* 64-byte complete form of an ondisk inode */
174 struct erofs_inode_extended {
175 __le16 i_format; /* inode format hints */
176
177 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
178 __le16 i_xattr_icount;
179 __le16 i_mode;
180 __le16 i_reserved;
181 __le64 i_size;
182 union erofs_inode_i_u i_u;
183
184 __le32 i_ino; /* only used for 32-bit stat compatibility */
185 __le32 i_uid;
186 __le32 i_gid;
187 __le64 i_mtime;
188 __le32 i_mtime_nsec;
189 __le32 i_nlink;
190 __u8 i_reserved2[16];
191 };
192
193 /*
194 * inline xattrs (n == i_xattr_icount):
195 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
196 * 12 bytes / \
197 * / \
198 * /-----------------------\
199 * | erofs_xattr_entries+ |
200 * +-----------------------+
201 * inline xattrs must starts in erofs_xattr_ibody_header,
202 * for read-only fs, no need to introduce h_refcount
203 */
204 struct erofs_xattr_ibody_header {
205 __le32 h_name_filter; /* bit value 1 indicates not-present */
206 __u8 h_shared_count;
207 __u8 h_reserved2[7];
208 __le32 h_shared_xattrs[]; /* shared xattr id array */
209 };
210
211 /* Name indexes */
212 #define EROFS_XATTR_INDEX_USER 1
213 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2
214 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
215 #define EROFS_XATTR_INDEX_TRUSTED 4
216 #define EROFS_XATTR_INDEX_LUSTRE 5
217 #define EROFS_XATTR_INDEX_SECURITY 6
218
219 /*
220 * bit 7 of e_name_index is set when it refers to a long xattr name prefix,
221 * while the remained lower bits represent the index of the prefix.
222 */
223 #define EROFS_XATTR_LONG_PREFIX 0x80
224 #define EROFS_XATTR_LONG_PREFIX_MASK 0x7f
225
226 #define EROFS_XATTR_FILTER_BITS 32
227 #define EROFS_XATTR_FILTER_DEFAULT UINT32_MAX
228 #define EROFS_XATTR_FILTER_SEED 0x25BBE08F
229
230 /* xattr entry (for both inline & shared xattrs) */
231 struct erofs_xattr_entry {
232 __u8 e_name_len; /* length of name */
233 __u8 e_name_index; /* attribute name index */
234 __le16 e_value_size; /* size of attribute value */
235 /* followed by e_name and e_value */
236 char e_name[]; /* attribute name */
237 };
238
239 /* long xattr name prefix */
240 struct erofs_xattr_long_prefix {
241 __u8 base_index; /* short xattr name prefix index */
242 char infix[]; /* infix apart from short prefix */
243 };
244
245 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
246 {
247 if (!i_xattr_icount)
248 return 0;
249
250 return sizeof(struct erofs_xattr_ibody_header) +
251 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
252 }
253
254 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
255
256 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
257 {
258 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
259 e->e_name_len + le16_to_cpu(e->e_value_size));
260 }
261
262 /* represent a zeroed chunk (hole) */
263 #define EROFS_NULL_ADDR -1
264
265 /* 4-byte block address array */
266 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32)
267
268 /* 8-byte inode chunk indexes */
269 struct erofs_inode_chunk_index {
270 __le16 advise; /* always 0, don't care for now */
271 __le16 device_id; /* back-end storage id (with bits masked) */
272 __le32 blkaddr; /* start block address of this inode chunk */
273 };
274
275 /* dirent sorts in alphabet order, thus we can do binary search */
276 struct erofs_dirent {
277 __le64 nid; /* node number */
278 __le16 nameoff; /* start offset of file name */
279 __u8 file_type; /* file type */
280 __u8 reserved; /* reserved */
281 } __packed;
282
283 /*
284 * EROFS file types should match generic FT_* types and
285 * it seems no need to add BUILD_BUG_ONs since potential
286 * unmatchness will break other fses as well...
287 */
288
289 #define EROFS_NAME_LEN 255
290
291 /* maximum supported size of a physical compression cluster */
292 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024)
293
294 /* available compression algorithm types (for h_algorithmtype) */
295 enum {
296 Z_EROFS_COMPRESSION_LZ4 = 0,
297 Z_EROFS_COMPRESSION_LZMA = 1,
298 Z_EROFS_COMPRESSION_DEFLATE = 2,
299 Z_EROFS_COMPRESSION_ZSTD = 3,
300 Z_EROFS_COMPRESSION_MAX
301 };
302 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1)
303
304 /* 14 bytes (+ length field = 16 bytes) */
305 struct z_erofs_lz4_cfgs {
306 __le16 max_distance;
307 __le16 max_pclusterblks;
308 u8 reserved[10];
309 } __packed;
310
311 /* 14 bytes (+ length field = 16 bytes) */
312 struct z_erofs_lzma_cfgs {
313 __le32 dict_size;
314 __le16 format;
315 u8 reserved[8];
316 } __packed;
317
318 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE)
319
320 /* 6 bytes (+ length field = 8 bytes) */
321 struct z_erofs_deflate_cfgs {
322 u8 windowbits; /* 8..15 for DEFLATE */
323 u8 reserved[5];
324 } __packed;
325
326 /* 6 bytes (+ length field = 8 bytes) */
327 struct z_erofs_zstd_cfgs {
328 u8 format;
329 u8 windowlog; /* windowLog - ZSTD_WINDOWLOG_ABSOLUTEMIN(10) */
330 u8 reserved[4];
331 } __packed;
332
333 #define Z_EROFS_ZSTD_MAX_DICT_SIZE Z_EROFS_PCLUSTER_MAX_SIZE
334
335 /*
336 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
337 * e.g. for 4k logical cluster size, 4B if compacted 2B is off;
338 * (4B) + 2B + (4B) if compacted 2B is on.
339 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
340 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
341 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on)
342 * bit 4 : interlaced plain pcluster (0 - off; 1 - on)
343 * bit 5 : fragment pcluster (0 - off; 1 - on)
344 */
345 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
346 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
347 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004
348 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008
349 #define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010
350 #define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020
351
352 #define Z_EROFS_FRAGMENT_INODE_BIT 7
353 struct z_erofs_map_header {
354 union {
355 /* fragment data offset in the packed inode */
356 __le32 h_fragmentoff;
357 struct {
358 __le16 h_reserved1;
359 /* indicates the encoded size of tailpacking data */
360 __le16 h_idata_size;
361 };
362 };
363 __le16 h_advise;
364 /*
365 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
366 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
367 */
368 __u8 h_algorithmtype;
369 /*
370 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
371 * bit 3-6 : reserved;
372 * bit 7 : move the whole file into packed inode or not.
373 */
374 __u8 h_clusterbits;
375 };
376
377 /*
378 * On-disk logical cluster type:
379 * 0 - literal (uncompressed) lcluster
380 * 1,3 - compressed lcluster (for HEAD lclusters)
381 * 2 - compressed lcluster (for NONHEAD lclusters)
382 *
383 * In detail,
384 * 0 - literal (uncompressed) lcluster,
385 * di_advise = 0
386 * di_clusterofs = the literal data offset of the lcluster
387 * di_blkaddr = the blkaddr of the literal pcluster
388 *
389 * 1,3 - compressed lcluster (for HEAD lclusters)
390 * di_advise = 1 or 3
391 * di_clusterofs = the decompressed data offset of the lcluster
392 * di_blkaddr = the blkaddr of the compressed pcluster
393 *
394 * 2 - compressed lcluster (for NONHEAD lclusters)
395 * di_advise = 2
396 * di_clusterofs =
397 * the decompressed data offset in its own HEAD lcluster
398 * di_u.delta[0] = distance to this HEAD lcluster
399 * di_u.delta[1] = distance to the next HEAD lcluster
400 */
401 enum {
402 Z_EROFS_LCLUSTER_TYPE_PLAIN = 0,
403 Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1,
404 Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2,
405 Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3,
406 Z_EROFS_LCLUSTER_TYPE_MAX
407 };
408
409 #define Z_EROFS_LI_LCLUSTER_TYPE_MASK (Z_EROFS_LCLUSTER_TYPE_MAX - 1)
410
411 /* (noncompact only, HEAD) This pcluster refers to partial decompressed data */
412 #define Z_EROFS_LI_PARTIAL_REF (1 << 15)
413
414 /*
415 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
416 * compressed block count of a compressed extent (in logical clusters, aka.
417 * block count of a pcluster).
418 */
419 #define Z_EROFS_LI_D0_CBLKCNT (1 << 11)
420
421 struct z_erofs_lcluster_index {
422 __le16 di_advise;
423 /* where to decompress in the head lcluster */
424 __le16 di_clusterofs;
425
426 union {
427 /* for the HEAD lclusters */
428 __le32 blkaddr;
429 /*
430 * for the NONHEAD lclusters
431 * [0] - distance to its HEAD lcluster
432 * [1] - distance to the next HEAD lcluster
433 */
434 __le16 delta[2];
435 } di_u;
436 };
437
438 #define Z_EROFS_FULL_INDEX_ALIGN(end) \
439 (ALIGN(end, 8) + sizeof(struct z_erofs_map_header) + 8)
440
441 /* check the EROFS on-disk layout strictly at compile time */
442 static inline void erofs_check_ondisk_layout_definitions(void)
443 {
444 const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) {
445 .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT
446 };
447
448 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
449 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
450 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
451 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
452 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
453 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4);
454 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8);
455 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
456 BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8);
457 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
458 /* keep in sync between 2 index structures for better extendibility */
459 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) !=
460 sizeof(struct z_erofs_lcluster_index));
461 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
462
463 /* exclude old compiler versions like gcc 7.5.0 */
464 BUILD_BUG_ON(__builtin_constant_p(fmh) ?
465 fmh != cpu_to_le64(1ULL << 63) : 0);
466 }
467
468 #endif
469
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