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 erofs_inode_is_data_compressed(unsigned int datamode)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 erofs_xattr_ibody_size(__le16 i_xattr_icount)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 erofs_xattr_entry_size(struct erofs_xattr_entry * e)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 encoded size of a physical compressed cluster */ 292 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 293 294 /* maximum supported decoded size of a physical compressed cluster */ 295 #define Z_EROFS_PCLUSTER_MAX_DSIZE (12 * 1024 * 1024) 296 297 /* available compression algorithm types (for h_algorithmtype) */ 298 enum { 299 Z_EROFS_COMPRESSION_LZ4 = 0, 300 Z_EROFS_COMPRESSION_LZMA = 1, 301 Z_EROFS_COMPRESSION_DEFLATE = 2, 302 Z_EROFS_COMPRESSION_ZSTD = 3, 303 Z_EROFS_COMPRESSION_MAX 304 }; 305 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 306 307 /* 14 bytes (+ length field = 16 bytes) */ 308 struct z_erofs_lz4_cfgs { 309 __le16 max_distance; 310 __le16 max_pclusterblks; 311 u8 reserved[10]; 312 } __packed; 313 314 /* 14 bytes (+ length field = 16 bytes) */ 315 struct z_erofs_lzma_cfgs { 316 __le32 dict_size; 317 __le16 format; 318 u8 reserved[8]; 319 } __packed; 320 321 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 322 323 /* 6 bytes (+ length field = 8 bytes) */ 324 struct z_erofs_deflate_cfgs { 325 u8 windowbits; /* 8..15 for DEFLATE */ 326 u8 reserved[5]; 327 } __packed; 328 329 /* 6 bytes (+ length field = 8 bytes) */ 330 struct z_erofs_zstd_cfgs { 331 u8 format; 332 u8 windowlog; /* windowLog - ZSTD_WINDOWLOG_ABSOLUTEMIN(10) */ 333 u8 reserved[4]; 334 } __packed; 335 336 #define Z_EROFS_ZSTD_MAX_DICT_SIZE Z_EROFS_PCLUSTER_MAX_SIZE 337 338 /* 339 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 340 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 341 * (4B) + 2B + (4B) if compacted 2B is on. 342 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 343 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 344 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) 345 * bit 4 : interlaced plain pcluster (0 - off; 1 - on) 346 * bit 5 : fragment pcluster (0 - off; 1 - on) 347 */ 348 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 349 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 350 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 351 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 352 #define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010 353 #define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020 354 355 #define Z_EROFS_FRAGMENT_INODE_BIT 7 356 struct z_erofs_map_header { 357 union { 358 /* fragment data offset in the packed inode */ 359 __le32 h_fragmentoff; 360 struct { 361 __le16 h_reserved1; 362 /* indicates the encoded size of tailpacking data */ 363 __le16 h_idata_size; 364 }; 365 }; 366 __le16 h_advise; 367 /* 368 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 369 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 370 */ 371 __u8 h_algorithmtype; 372 /* 373 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 374 * bit 3-6 : reserved; 375 * bit 7 : move the whole file into packed inode or not. 376 */ 377 __u8 h_clusterbits; 378 }; 379 380 /* 381 * On-disk logical cluster type: 382 * 0 - literal (uncompressed) lcluster 383 * 1,3 - compressed lcluster (for HEAD lclusters) 384 * 2 - compressed lcluster (for NONHEAD lclusters) 385 * 386 * In detail, 387 * 0 - literal (uncompressed) lcluster, 388 * di_advise = 0 389 * di_clusterofs = the literal data offset of the lcluster 390 * di_blkaddr = the blkaddr of the literal pcluster 391 * 392 * 1,3 - compressed lcluster (for HEAD lclusters) 393 * di_advise = 1 or 3 394 * di_clusterofs = the decompressed data offset of the lcluster 395 * di_blkaddr = the blkaddr of the compressed pcluster 396 * 397 * 2 - compressed lcluster (for NONHEAD lclusters) 398 * di_advise = 2 399 * di_clusterofs = 400 * the decompressed data offset in its own HEAD lcluster 401 * di_u.delta[0] = distance to this HEAD lcluster 402 * di_u.delta[1] = distance to the next HEAD lcluster 403 */ 404 enum { 405 Z_EROFS_LCLUSTER_TYPE_PLAIN = 0, 406 Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1, 407 Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2, 408 Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3, 409 Z_EROFS_LCLUSTER_TYPE_MAX 410 }; 411 412 #define Z_EROFS_LI_LCLUSTER_TYPE_MASK (Z_EROFS_LCLUSTER_TYPE_MAX - 1) 413 414 /* (noncompact only, HEAD) This pcluster refers to partial decompressed data */ 415 #define Z_EROFS_LI_PARTIAL_REF (1 << 15) 416 417 /* 418 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 419 * compressed block count of a compressed extent (in logical clusters, aka. 420 * block count of a pcluster). 421 */ 422 #define Z_EROFS_LI_D0_CBLKCNT (1 << 11) 423 424 struct z_erofs_lcluster_index { 425 __le16 di_advise; 426 /* where to decompress in the head lcluster */ 427 __le16 di_clusterofs; 428 429 union { 430 /* for the HEAD lclusters */ 431 __le32 blkaddr; 432 /* 433 * for the NONHEAD lclusters 434 * [0] - distance to its HEAD lcluster 435 * [1] - distance to the next HEAD lcluster 436 */ 437 __le16 delta[2]; 438 } di_u; 439 }; 440 441 #define Z_EROFS_FULL_INDEX_ALIGN(end) \ 442 (ALIGN(end, 8) + sizeof(struct z_erofs_map_header) + 8) 443 444 /* check the EROFS on-disk layout strictly at compile time */ erofs_check_ondisk_layout_definitions(void)445 static inline void erofs_check_ondisk_layout_definitions(void) 446 { 447 const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) { 448 .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT 449 }; 450 451 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 452 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 453 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 454 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 455 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 456 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 457 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 458 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 459 BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8); 460 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 461 /* keep in sync between 2 index structures for better extendibility */ 462 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 463 sizeof(struct z_erofs_lcluster_index)); 464 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 465 466 /* exclude old compiler versions like gcc 7.5.0 */ 467 BUILD_BUG_ON(__builtin_constant_p(fmh) ? 468 fmh != cpu_to_le64(1ULL << 63) : 0); 469 } 470 471 #endif 472