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 17 /* 18 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should 19 * be incompatible with this kernel version. 20 */ 21 #define EROFS_FEATURE_INCOMPAT_ZERO_PADDING 0x00000001 22 #define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002 23 #define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002 24 #define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004 25 #define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008 26 #define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008 27 #define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010 28 #define EROFS_FEATURE_INCOMPAT_FRAGMENTS 0x00000020 29 #define EROFS_FEATURE_INCOMPAT_DEDUPE 0x00000020 30 #define EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES 0x00000040 31 #define EROFS_ALL_FEATURE_INCOMPAT \ 32 (EROFS_FEATURE_INCOMPAT_ZERO_PADDING | \ 33 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \ 34 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \ 35 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \ 36 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \ 37 EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 | \ 38 EROFS_FEATURE_INCOMPAT_ZTAILPACKING | \ 39 EROFS_FEATURE_INCOMPAT_FRAGMENTS | \ 40 EROFS_FEATURE_INCOMPAT_DEDUPE | \ 41 EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES) 42 43 #define EROFS_SB_EXTSLOT_SIZE 16 44 45 struct erofs_deviceslot { 46 u8 tag[64]; /* digest(sha256), etc. */ 47 __le32 blocks; /* total fs blocks of this device */ 48 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */ 49 u8 reserved[56]; 50 }; 51 #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot) 52 53 /* erofs on-disk super block (currently 128 bytes) */ 54 struct erofs_super_block { 55 __le32 magic; /* file system magic number */ 56 __le32 checksum; /* crc32c(super_block) */ 57 __le32 feature_compat; 58 __u8 blkszbits; /* filesystem block size in bit shift */ 59 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ 60 61 __le16 root_nid; /* nid of root directory */ 62 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 63 64 __le64 build_time; /* compact inode time derivation */ 65 __le32 build_time_nsec; /* compact inode time derivation in ns scale */ 66 __le32 blocks; /* used for statfs */ 67 __le32 meta_blkaddr; /* start block address of metadata area */ 68 __le32 xattr_blkaddr; /* start block address of shared xattr area */ 69 __u8 uuid[16]; /* 128-bit uuid for volume */ 70 __u8 volume_name[16]; /* volume name */ 71 __le32 feature_incompat; 72 union { 73 /* bitmap for available compression algorithms */ 74 __le16 available_compr_algs; 75 /* customized sliding window size instead of 64k by default */ 76 __le16 lz4_max_distance; 77 } __packed u1; 78 __le16 extra_devices; /* # of devices besides the primary device */ 79 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */ 80 __u8 dirblkbits; /* directory block size in bit shift */ 81 __u8 xattr_prefix_count; /* # of long xattr name prefixes */ 82 __le32 xattr_prefix_start; /* start of long xattr prefixes */ 83 __le64 packed_nid; /* nid of the special packed inode */ 84 __u8 reserved2[24]; 85 }; 86 87 /* 88 * EROFS inode datalayout (i_format in on-disk inode): 89 * 0 - uncompressed flat inode without tail-packing inline data: 90 * 1 - compressed inode with non-compact indexes: 91 * 2 - uncompressed flat inode with tail-packing inline data: 92 * 3 - compressed inode with compact indexes: 93 * 4 - chunk-based inode with (optional) multi-device support: 94 * 5~7 - reserved 95 */ 96 enum { 97 EROFS_INODE_FLAT_PLAIN = 0, 98 EROFS_INODE_COMPRESSED_FULL = 1, 99 EROFS_INODE_FLAT_INLINE = 2, 100 EROFS_INODE_COMPRESSED_COMPACT = 3, 101 EROFS_INODE_CHUNK_BASED = 4, 102 EROFS_INODE_DATALAYOUT_MAX 103 }; 104 105 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 106 { 107 return datamode == EROFS_INODE_COMPRESSED_COMPACT || 108 datamode == EROFS_INODE_COMPRESSED_FULL; 109 } 110 111 /* bit definitions of inode i_format */ 112 #define EROFS_I_VERSION_MASK 0x01 113 #define EROFS_I_DATALAYOUT_MASK 0x07 114 115 #define EROFS_I_VERSION_BIT 0 116 #define EROFS_I_DATALAYOUT_BIT 1 117 #define EROFS_I_ALL_BIT 4 118 119 #define EROFS_I_ALL ((1 << EROFS_I_ALL_BIT) - 1) 120 121 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */ 122 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F 123 /* with chunk indexes or just a 4-byte blkaddr array */ 124 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020 125 126 #define EROFS_CHUNK_FORMAT_ALL \ 127 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES) 128 129 /* 32-byte on-disk inode */ 130 #define EROFS_INODE_LAYOUT_COMPACT 0 131 /* 64-byte on-disk inode */ 132 #define EROFS_INODE_LAYOUT_EXTENDED 1 133 134 struct erofs_inode_chunk_info { 135 __le16 format; /* chunk blkbits, etc. */ 136 __le16 reserved; 137 }; 138 139 union erofs_inode_i_u { 140 /* total compressed blocks for compressed inodes */ 141 __le32 compressed_blocks; 142 143 /* block address for uncompressed flat inodes */ 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 }; 152 153 /* 32-byte reduced form of an ondisk inode */ 154 struct erofs_inode_compact { 155 __le16 i_format; /* inode format hints */ 156 157 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 158 __le16 i_xattr_icount; 159 __le16 i_mode; 160 __le16 i_nlink; 161 __le32 i_size; 162 __le32 i_reserved; 163 union erofs_inode_i_u i_u; 164 165 __le32 i_ino; /* only used for 32-bit stat compatibility */ 166 __le16 i_uid; 167 __le16 i_gid; 168 __le32 i_reserved2; 169 }; 170 171 /* 64-byte complete form of an ondisk inode */ 172 struct erofs_inode_extended { 173 __le16 i_format; /* inode format hints */ 174 175 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 176 __le16 i_xattr_icount; 177 __le16 i_mode; 178 __le16 i_reserved; 179 __le64 i_size; 180 union erofs_inode_i_u i_u; 181 182 __le32 i_ino; /* only used for 32-bit stat compatibility */ 183 __le32 i_uid; 184 __le32 i_gid; 185 __le64 i_mtime; 186 __le32 i_mtime_nsec; 187 __le32 i_nlink; 188 __u8 i_reserved2[16]; 189 }; 190 191 /* 192 * inline xattrs (n == i_xattr_icount): 193 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 194 * 12 bytes / \ 195 * / \ 196 * /-----------------------\ 197 * | erofs_xattr_entries+ | 198 * +-----------------------+ 199 * inline xattrs must starts in erofs_xattr_ibody_header, 200 * for read-only fs, no need to introduce h_refcount 201 */ 202 struct erofs_xattr_ibody_header { 203 __le32 h_reserved; 204 __u8 h_shared_count; 205 __u8 h_reserved2[7]; 206 __le32 h_shared_xattrs[]; /* shared xattr id array */ 207 }; 208 209 /* Name indexes */ 210 #define EROFS_XATTR_INDEX_USER 1 211 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 212 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 213 #define EROFS_XATTR_INDEX_TRUSTED 4 214 #define EROFS_XATTR_INDEX_LUSTRE 5 215 #define EROFS_XATTR_INDEX_SECURITY 6 216 217 /* 218 * bit 7 of e_name_index is set when it refers to a long xattr name prefix, 219 * while the remained lower bits represent the index of the prefix. 220 */ 221 #define EROFS_XATTR_LONG_PREFIX 0x80 222 #define EROFS_XATTR_LONG_PREFIX_MASK 0x7f 223 224 /* xattr entry (for both inline & shared xattrs) */ 225 struct erofs_xattr_entry { 226 __u8 e_name_len; /* length of name */ 227 __u8 e_name_index; /* attribute name index */ 228 __le16 e_value_size; /* size of attribute value */ 229 /* followed by e_name and e_value */ 230 char e_name[]; /* attribute name */ 231 }; 232 233 /* long xattr name prefix */ 234 struct erofs_xattr_long_prefix { 235 __u8 base_index; /* short xattr name prefix index */ 236 char infix[]; /* infix apart from short prefix */ 237 }; 238 239 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 240 { 241 if (!i_xattr_icount) 242 return 0; 243 244 return sizeof(struct erofs_xattr_ibody_header) + 245 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 246 } 247 248 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 249 250 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 251 { 252 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 253 e->e_name_len + le16_to_cpu(e->e_value_size)); 254 } 255 256 /* represent a zeroed chunk (hole) */ 257 #define EROFS_NULL_ADDR -1 258 259 /* 4-byte block address array */ 260 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 261 262 /* 8-byte inode chunk indexes */ 263 struct erofs_inode_chunk_index { 264 __le16 advise; /* always 0, don't care for now */ 265 __le16 device_id; /* back-end storage id (with bits masked) */ 266 __le32 blkaddr; /* start block address of this inode chunk */ 267 }; 268 269 /* dirent sorts in alphabet order, thus we can do binary search */ 270 struct erofs_dirent { 271 __le64 nid; /* node number */ 272 __le16 nameoff; /* start offset of file name */ 273 __u8 file_type; /* file type */ 274 __u8 reserved; /* reserved */ 275 } __packed; 276 277 /* 278 * EROFS file types should match generic FT_* types and 279 * it seems no need to add BUILD_BUG_ONs since potential 280 * unmatchness will break other fses as well... 281 */ 282 283 #define EROFS_NAME_LEN 255 284 285 /* maximum supported size of a physical compression cluster */ 286 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 287 288 /* available compression algorithm types (for h_algorithmtype) */ 289 enum { 290 Z_EROFS_COMPRESSION_LZ4 = 0, 291 Z_EROFS_COMPRESSION_LZMA = 1, 292 Z_EROFS_COMPRESSION_MAX 293 }; 294 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 295 296 /* 14 bytes (+ length field = 16 bytes) */ 297 struct z_erofs_lz4_cfgs { 298 __le16 max_distance; 299 __le16 max_pclusterblks; 300 u8 reserved[10]; 301 } __packed; 302 303 /* 14 bytes (+ length field = 16 bytes) */ 304 struct z_erofs_lzma_cfgs { 305 __le32 dict_size; 306 __le16 format; 307 u8 reserved[8]; 308 } __packed; 309 310 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 311 312 /* 313 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 314 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 315 * (4B) + 2B + (4B) if compacted 2B is on. 316 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 317 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 318 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) 319 * bit 4 : interlaced plain pcluster (0 - off; 1 - on) 320 * bit 5 : fragment pcluster (0 - off; 1 - on) 321 */ 322 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 323 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 324 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 325 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 326 #define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010 327 #define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020 328 329 #define Z_EROFS_FRAGMENT_INODE_BIT 7 330 struct z_erofs_map_header { 331 union { 332 /* fragment data offset in the packed inode */ 333 __le32 h_fragmentoff; 334 struct { 335 __le16 h_reserved1; 336 /* indicates the encoded size of tailpacking data */ 337 __le16 h_idata_size; 338 }; 339 }; 340 __le16 h_advise; 341 /* 342 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 343 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 344 */ 345 __u8 h_algorithmtype; 346 /* 347 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 348 * bit 3-6 : reserved; 349 * bit 7 : move the whole file into packed inode or not. 350 */ 351 __u8 h_clusterbits; 352 }; 353 354 /* 355 * On-disk logical cluster type: 356 * 0 - literal (uncompressed) lcluster 357 * 1,3 - compressed lcluster (for HEAD lclusters) 358 * 2 - compressed lcluster (for NONHEAD lclusters) 359 * 360 * In detail, 361 * 0 - literal (uncompressed) lcluster, 362 * di_advise = 0 363 * di_clusterofs = the literal data offset of the lcluster 364 * di_blkaddr = the blkaddr of the literal pcluster 365 * 366 * 1,3 - compressed lcluster (for HEAD lclusters) 367 * di_advise = 1 or 3 368 * di_clusterofs = the decompressed data offset of the lcluster 369 * di_blkaddr = the blkaddr of the compressed pcluster 370 * 371 * 2 - compressed lcluster (for NONHEAD lclusters) 372 * di_advise = 2 373 * di_clusterofs = 374 * the decompressed data offset in its own HEAD lcluster 375 * di_u.delta[0] = distance to this HEAD lcluster 376 * di_u.delta[1] = distance to the next HEAD lcluster 377 */ 378 enum { 379 Z_EROFS_LCLUSTER_TYPE_PLAIN = 0, 380 Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1, 381 Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2, 382 Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3, 383 Z_EROFS_LCLUSTER_TYPE_MAX 384 }; 385 386 #define Z_EROFS_LI_LCLUSTER_TYPE_BITS 2 387 #define Z_EROFS_LI_LCLUSTER_TYPE_BIT 0 388 389 /* (noncompact only, HEAD) This pcluster refers to partial decompressed data */ 390 #define Z_EROFS_LI_PARTIAL_REF (1 << 15) 391 392 /* 393 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 394 * compressed block count of a compressed extent (in logical clusters, aka. 395 * block count of a pcluster). 396 */ 397 #define Z_EROFS_LI_D0_CBLKCNT (1 << 11) 398 399 struct z_erofs_lcluster_index { 400 __le16 di_advise; 401 /* where to decompress in the head lcluster */ 402 __le16 di_clusterofs; 403 404 union { 405 /* for the HEAD lclusters */ 406 __le32 blkaddr; 407 /* 408 * for the NONHEAD lclusters 409 * [0] - distance to its HEAD lcluster 410 * [1] - distance to the next HEAD lcluster 411 */ 412 __le16 delta[2]; 413 } di_u; 414 }; 415 416 #define Z_EROFS_FULL_INDEX_ALIGN(end) \ 417 (ALIGN(end, 8) + sizeof(struct z_erofs_map_header) + 8) 418 419 /* check the EROFS on-disk layout strictly at compile time */ 420 static inline void erofs_check_ondisk_layout_definitions(void) 421 { 422 const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) { 423 .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT 424 }; 425 426 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 427 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 428 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 429 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 430 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 431 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 432 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 433 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 434 BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8); 435 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 436 /* keep in sync between 2 index structures for better extendibility */ 437 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 438 sizeof(struct z_erofs_lcluster_index)); 439 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 440 441 BUILD_BUG_ON(BIT(Z_EROFS_LI_LCLUSTER_TYPE_BITS) < 442 Z_EROFS_LCLUSTER_TYPE_MAX - 1); 443 /* exclude old compiler versions like gcc 7.5.0 */ 444 BUILD_BUG_ON(__builtin_constant_p(fmh) ? 445 fmh != cpu_to_le64(1ULL << 63) : 0); 446 } 447 448 #endif 449