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 /* to allow for x86 boot sectors and other oddities. */ 13 #define EROFS_SUPER_OFFSET 1024 14 15 #define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001 16 #define EROFS_FEATURE_COMPAT_MTIME 0x00000002 17 #define EROFS_FEATURE_COMPAT_XATTR_FILTER 0x00000004 18 19 /* 20 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should 21 * be incompatible with this kernel version. 22 */ 23 #define EROFS_FEATURE_INCOMPAT_ZERO_PADDING 0x00000001 24 #define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002 25 #define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002 26 #define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004 27 #define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008 28 #define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008 29 #define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010 30 #define EROFS_FEATURE_INCOMPAT_FRAGMENTS 0x00000020 31 #define EROFS_FEATURE_INCOMPAT_DEDUPE 0x00000020 32 #define EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES 0x00000040 33 #define EROFS_FEATURE_INCOMPAT_48BIT 0x00000080 34 #define EROFS_ALL_FEATURE_INCOMPAT \ 35 ((EROFS_FEATURE_INCOMPAT_48BIT << 1) - 1) 36 37 #define EROFS_SB_EXTSLOT_SIZE 16 38 39 struct erofs_deviceslot { 40 u8 tag[64]; /* digest(sha256), etc. */ 41 __le32 blocks_lo; /* total blocks count of this device */ 42 __le32 uniaddr_lo; /* unified starting block of this device */ 43 __le32 blocks_hi; /* total blocks count MSB */ 44 __le16 uniaddr_hi; /* unified starting block MSB */ 45 u8 reserved[50]; 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 to avoid unexpected on-disk overlap */ 53 __le32 feature_compat; 54 __u8 blkszbits; /* filesystem block size in bit shift */ 55 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ 56 union { 57 __le16 rootnid_2b; /* nid of root directory */ 58 __le16 blocks_hi; /* (48BIT on) blocks count MSB */ 59 } __packed rb; 60 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 61 __le64 epoch; /* base seconds used for compact inodes */ 62 __le32 fixed_nsec; /* fixed nanoseconds for compact inodes */ 63 __le32 blocks_lo; /* blocks count LSB */ 64 __le32 meta_blkaddr; /* start block address of metadata area */ 65 __le32 xattr_blkaddr; /* start block address of shared xattr area */ 66 __u8 uuid[16]; /* 128-bit uuid for volume */ 67 __u8 volume_name[16]; /* volume name */ 68 __le32 feature_incompat; 69 union { 70 /* bitmap for available compression algorithms */ 71 __le16 available_compr_algs; 72 /* customized sliding window size instead of 64k by default */ 73 __le16 lz4_max_distance; 74 } __packed u1; 75 __le16 extra_devices; /* # of devices besides the primary device */ 76 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */ 77 __u8 dirblkbits; /* directory block size in bit shift */ 78 __u8 xattr_prefix_count; /* # of long xattr name prefixes */ 79 __le32 xattr_prefix_start; /* start of long xattr prefixes */ 80 __le64 packed_nid; /* nid of the special packed inode */ 81 __u8 xattr_filter_reserved; /* reserved for xattr name filter */ 82 __u8 reserved[3]; 83 __le32 build_time; /* seconds added to epoch for mkfs time */ 84 __le64 rootnid_8b; /* (48BIT on) nid of root directory */ 85 __u8 reserved2[8]; 86 }; 87 88 /* 89 * EROFS inode datalayout (i_format in on-disk inode): 90 * 0 - uncompressed flat inode without tail-packing inline data: 91 * 1 - compressed inode with non-compact indexes: 92 * 2 - uncompressed flat inode with tail-packing inline data: 93 * 3 - compressed inode with compact indexes: 94 * 4 - chunk-based inode with (optional) multi-device support: 95 * 5~7 - reserved 96 */ 97 enum { 98 EROFS_INODE_FLAT_PLAIN = 0, 99 EROFS_INODE_COMPRESSED_FULL = 1, 100 EROFS_INODE_FLAT_INLINE = 2, 101 EROFS_INODE_COMPRESSED_COMPACT = 3, 102 EROFS_INODE_CHUNK_BASED = 4, 103 EROFS_INODE_DATALAYOUT_MAX 104 }; 105 106 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 107 { 108 return datamode == EROFS_INODE_COMPRESSED_COMPACT || 109 datamode == EROFS_INODE_COMPRESSED_FULL; 110 } 111 112 /* bit definitions of inode i_format */ 113 #define EROFS_I_VERSION_MASK 0x01 114 #define EROFS_I_DATALAYOUT_MASK 0x07 115 116 #define EROFS_I_VERSION_BIT 0 117 #define EROFS_I_DATALAYOUT_BIT 1 118 #define EROFS_I_NLINK_1_BIT 4 /* non-directory compact inodes only */ 119 #define EROFS_I_DOT_OMITTED_BIT 4 /* (directories) omit the `.` dirent */ 120 #define EROFS_I_ALL ((1 << (EROFS_I_NLINK_1_BIT + 1)) - 1) 121 122 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */ 123 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F 124 /* with chunk indexes or just a 4-byte block array */ 125 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020 126 #define EROFS_CHUNK_FORMAT_48BIT 0x0040 127 128 #define EROFS_CHUNK_FORMAT_ALL ((EROFS_CHUNK_FORMAT_48BIT << 1) - 1) 129 130 /* 32-byte on-disk inode */ 131 #define EROFS_INODE_LAYOUT_COMPACT 0 132 /* 64-byte on-disk inode */ 133 #define EROFS_INODE_LAYOUT_EXTENDED 1 134 135 struct erofs_inode_chunk_info { 136 __le16 format; /* chunk blkbits, etc. */ 137 __le16 reserved; 138 }; 139 140 union erofs_inode_i_u { 141 __le32 blocks_lo; /* total blocks count (if compressed inodes) */ 142 __le32 startblk_lo; /* starting block number (if flat inodes) */ 143 __le32 rdev; /* device ID (if special inodes) */ 144 struct erofs_inode_chunk_info c; 145 }; 146 147 union erofs_inode_i_nb { 148 __le16 nlink; /* if EROFS_I_NLINK_1_BIT is unset */ 149 __le16 blocks_hi; /* total blocks count MSB */ 150 __le16 startblk_hi; /* starting block number MSB */ 151 } __packed; 152 153 /* 32-byte reduced form of an ondisk inode */ 154 struct erofs_inode_compact { 155 __le16 i_format; /* inode format hints */ 156 __le16 i_xattr_icount; 157 __le16 i_mode; 158 union erofs_inode_i_nb i_nb; 159 __le32 i_size; 160 __le32 i_mtime; 161 union erofs_inode_i_u i_u; 162 163 __le32 i_ino; /* only used for 32-bit stat compatibility */ 164 __le16 i_uid; 165 __le16 i_gid; 166 __le32 i_reserved; 167 }; 168 169 /* 64-byte complete form of an ondisk inode */ 170 struct erofs_inode_extended { 171 __le16 i_format; /* inode format hints */ 172 __le16 i_xattr_icount; 173 __le16 i_mode; 174 union erofs_inode_i_nb i_nb; 175 __le64 i_size; 176 union erofs_inode_i_u i_u; 177 178 __le32 i_ino; /* only used for 32-bit stat compatibility */ 179 __le32 i_uid; 180 __le32 i_gid; 181 __le64 i_mtime; 182 __le32 i_mtime_nsec; 183 __le32 i_nlink; 184 __u8 i_reserved2[16]; 185 }; 186 187 /* 188 * inline xattrs (n == i_xattr_icount): 189 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 190 * 12 bytes / \ 191 * / \ 192 * /-----------------------\ 193 * | erofs_xattr_entries+ | 194 * +-----------------------+ 195 * inline xattrs must starts in erofs_xattr_ibody_header, 196 * for read-only fs, no need to introduce h_refcount 197 */ 198 struct erofs_xattr_ibody_header { 199 __le32 h_name_filter; /* bit value 1 indicates not-present */ 200 __u8 h_shared_count; 201 __u8 h_reserved2[7]; 202 __le32 h_shared_xattrs[]; /* shared xattr id array */ 203 }; 204 205 /* Name indexes */ 206 #define EROFS_XATTR_INDEX_USER 1 207 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 208 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 209 #define EROFS_XATTR_INDEX_TRUSTED 4 210 #define EROFS_XATTR_INDEX_LUSTRE 5 211 #define EROFS_XATTR_INDEX_SECURITY 6 212 213 /* 214 * bit 7 of e_name_index is set when it refers to a long xattr name prefix, 215 * while the remained lower bits represent the index of the prefix. 216 */ 217 #define EROFS_XATTR_LONG_PREFIX 0x80 218 #define EROFS_XATTR_LONG_PREFIX_MASK 0x7f 219 220 #define EROFS_XATTR_FILTER_BITS 32 221 #define EROFS_XATTR_FILTER_DEFAULT UINT32_MAX 222 #define EROFS_XATTR_FILTER_SEED 0x25BBE08F 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 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 245 return sizeof(struct erofs_xattr_ibody_header) + 246 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 247 } 248 249 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 250 251 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 252 { 253 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 254 e->e_name_len + le16_to_cpu(e->e_value_size)); 255 } 256 257 /* represent a zeroed chunk (hole) */ 258 #define EROFS_NULL_ADDR -1 259 260 /* 4-byte block address array */ 261 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 262 263 /* 8-byte inode chunk index */ 264 struct erofs_inode_chunk_index { 265 __le16 startblk_hi; /* starting block number MSB */ 266 __le16 device_id; /* back-end storage id (with bits masked) */ 267 __le32 startblk_lo; /* starting block number of this chunk */ 268 }; 269 270 /* dirent sorts in alphabet order, thus we can do binary search */ 271 struct erofs_dirent { 272 __le64 nid; /* node number */ 273 __le16 nameoff; /* start offset of file name */ 274 __u8 file_type; /* file type */ 275 __u8 reserved; /* reserved */ 276 } __packed; 277 278 /* 279 * EROFS file types should match generic FT_* types and 280 * it seems no need to add BUILD_BUG_ONs since potential 281 * unmatchness will break other fses as well... 282 */ 283 284 #define EROFS_NAME_LEN 255 285 286 /* maximum supported encoded size of a physical compressed cluster */ 287 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 288 289 /* maximum supported decoded size of a physical compressed cluster */ 290 #define Z_EROFS_PCLUSTER_MAX_DSIZE (12 * 1024 * 1024) 291 292 /* available compression algorithm types (for h_algorithmtype) */ 293 enum { 294 Z_EROFS_COMPRESSION_LZ4 = 0, 295 Z_EROFS_COMPRESSION_LZMA = 1, 296 Z_EROFS_COMPRESSION_DEFLATE = 2, 297 Z_EROFS_COMPRESSION_ZSTD = 3, 298 Z_EROFS_COMPRESSION_MAX 299 }; 300 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 301 302 /* 14 bytes (+ length field = 16 bytes) */ 303 struct z_erofs_lz4_cfgs { 304 __le16 max_distance; 305 __le16 max_pclusterblks; 306 u8 reserved[10]; 307 } __packed; 308 309 /* 14 bytes (+ length field = 16 bytes) */ 310 struct z_erofs_lzma_cfgs { 311 __le32 dict_size; 312 __le16 format; 313 u8 reserved[8]; 314 } __packed; 315 316 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 317 318 /* 6 bytes (+ length field = 8 bytes) */ 319 struct z_erofs_deflate_cfgs { 320 u8 windowbits; /* 8..15 for DEFLATE */ 321 u8 reserved[5]; 322 } __packed; 323 324 /* 6 bytes (+ length field = 8 bytes) */ 325 struct z_erofs_zstd_cfgs { 326 u8 format; 327 u8 windowlog; /* windowLog - ZSTD_WINDOWLOG_ABSOLUTEMIN(10) */ 328 u8 reserved[4]; 329 } __packed; 330 331 #define Z_EROFS_ZSTD_MAX_DICT_SIZE Z_EROFS_PCLUSTER_MAX_SIZE 332 333 /* 334 * Enable COMPACTED_2B for EROFS_INODE_COMPRESSED_COMPACT inodes: 335 * 4B (disabled) vs 4B+2B+4B (enabled) 336 */ 337 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 338 /* Enable extent metadata for EROFS_INODE_COMPRESSED_FULL inodes */ 339 #define Z_EROFS_ADVISE_EXTENTS 0x0001 340 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 341 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 342 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 343 #define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010 344 #define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020 345 /* Indicate the record size for each extent if extent metadata is used */ 346 #define Z_EROFS_ADVISE_EXTRECSZ_BIT 1 347 #define Z_EROFS_ADVISE_EXTRECSZ_MASK 0x3 348 349 #define Z_EROFS_FRAGMENT_INODE_BIT 7 350 struct z_erofs_map_header { 351 union { 352 /* fragment data offset in the packed inode */ 353 __le32 h_fragmentoff; 354 struct { 355 __le16 h_reserved1; 356 /* indicates the encoded size of tailpacking data */ 357 __le16 h_idata_size; 358 }; 359 __le32 h_extents_lo; /* extent count LSB */ 360 }; 361 __le16 h_advise; 362 union { 363 struct { 364 /* algorithm type (bit 0-3: HEAD1; bit 4-7: HEAD2) */ 365 __u8 h_algorithmtype; 366 /* 367 * bit 0-3 : logical cluster bits - blkszbits 368 * bit 4-6 : reserved 369 * bit 7 : pack the whole file into packed inode 370 */ 371 __u8 h_clusterbits; 372 } __packed; 373 __le16 h_extents_hi; /* extent count MSB */ 374 } __packed; 375 }; 376 377 enum { 378 Z_EROFS_LCLUSTER_TYPE_PLAIN = 0, 379 Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1, 380 Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2, 381 Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3, 382 Z_EROFS_LCLUSTER_TYPE_MAX 383 }; 384 385 #define Z_EROFS_LI_LCLUSTER_TYPE_MASK (Z_EROFS_LCLUSTER_TYPE_MAX - 1) 386 387 /* (noncompact only, HEAD) This pcluster refers to partial decompressed data */ 388 #define Z_EROFS_LI_PARTIAL_REF (1 << 15) 389 390 /* Set on 1st non-head lcluster to store compressed block counti (in blocks) */ 391 #define Z_EROFS_LI_D0_CBLKCNT (1 << 11) 392 393 struct z_erofs_lcluster_index { 394 __le16 di_advise; 395 /* where to decompress in the head lcluster */ 396 __le16 di_clusterofs; 397 398 union { 399 __le32 blkaddr; /* for the HEAD lclusters */ 400 /* 401 * [0] - distance to its HEAD lcluster 402 * [1] - distance to the next HEAD lcluster 403 */ 404 __le16 delta[2]; /* for the NONHEAD lclusters */ 405 } di_u; 406 }; 407 408 #define Z_EROFS_MAP_HEADER_END(end) \ 409 (ALIGN(end, 8) + sizeof(struct z_erofs_map_header)) 410 #define Z_EROFS_FULL_INDEX_START(end) (Z_EROFS_MAP_HEADER_END(end) + 8) 411 412 #define Z_EROFS_EXTENT_PLEN_PARTIAL BIT(27) 413 #define Z_EROFS_EXTENT_PLEN_FMT_BIT 28 414 #define Z_EROFS_EXTENT_PLEN_MASK ((Z_EROFS_PCLUSTER_MAX_SIZE << 1) - 1) 415 struct z_erofs_extent { 416 __le32 plen; /* encoded length */ 417 __le32 pstart_lo; /* physical offset */ 418 __le32 pstart_hi; /* physical offset MSB */ 419 __le32 lstart_lo; /* logical offset */ 420 __le32 lstart_hi; /* logical offset MSB (>= 4GiB inodes) */ 421 __u8 reserved[12]; /* for future use */ 422 }; 423 424 static inline int z_erofs_extent_recsize(unsigned int advise) 425 { 426 return 4 << ((advise >> Z_EROFS_ADVISE_EXTRECSZ_BIT) & 427 Z_EROFS_ADVISE_EXTRECSZ_MASK); 428 } 429 430 /* check the EROFS on-disk layout strictly at compile time */ 431 static inline void erofs_check_ondisk_layout_definitions(void) 432 { 433 const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) { 434 .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT 435 }; 436 437 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 438 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 439 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 440 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 441 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 442 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 443 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 444 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 445 BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8); 446 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 447 /* keep in sync between 2 index structures for better extendibility */ 448 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 449 sizeof(struct z_erofs_lcluster_index)); 450 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 451 452 /* exclude old compiler versions like gcc 7.5.0 */ 453 BUILD_BUG_ON(__builtin_constant_p(fmh) ? 454 fmh != cpu_to_le64(1ULL << 63) : 0); 455 } 456 457 #endif 458