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 46struct 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) */ 55struct 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 */ 98enum { 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 107static 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 136struct erofs_inode_chunk_info { 137 __le16 format; /* chunk blkbits, etc. */ 138 __le16 reserved; 139}; 140 141union 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 */ 156struct 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 */ 174struct 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 */ 204struct 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) */ 231struct 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 */ 240struct erofs_xattr_long_prefix { 241 __u8 base_index; /* short xattr name prefix index */ 242 char infix[]; /* infix apart from short prefix */ 243}; 244 245static 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 256static 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 */ 269struct 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 */ 276struct 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) */ 295enum { 296 Z_EROFS_COMPRESSION_LZ4 = 0, 297 Z_EROFS_COMPRESSION_LZMA = 1, 298 Z_EROFS_COMPRESSION_DEFLATE = 2, 299 Z_EROFS_COMPRESSION_MAX 300}; 301#define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 302 303/* 14 bytes (+ length field = 16 bytes) */ 304struct z_erofs_lz4_cfgs { 305 __le16 max_distance; 306 __le16 max_pclusterblks; 307 u8 reserved[10]; 308} __packed; 309 310/* 14 bytes (+ length field = 16 bytes) */ 311struct z_erofs_lzma_cfgs { 312 __le32 dict_size; 313 __le16 format; 314 u8 reserved[8]; 315} __packed; 316 317#define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 318 319/* 6 bytes (+ length field = 8 bytes) */ 320struct z_erofs_deflate_cfgs { 321 u8 windowbits; /* 8..15 for DEFLATE */ 322 u8 reserved[5]; 323} __packed; 324 325/* 326 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 327 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 328 * (4B) + 2B + (4B) if compacted 2B is on. 329 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 330 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 331 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) 332 * bit 4 : interlaced plain pcluster (0 - off; 1 - on) 333 * bit 5 : fragment pcluster (0 - off; 1 - on) 334 */ 335#define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 336#define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 337#define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 338#define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 339#define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010 340#define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020 341 342#define Z_EROFS_FRAGMENT_INODE_BIT 7 343struct z_erofs_map_header { 344 union { 345 /* fragment data offset in the packed inode */ 346 __le32 h_fragmentoff; 347 struct { 348 __le16 h_reserved1; 349 /* indicates the encoded size of tailpacking data */ 350 __le16 h_idata_size; 351 }; 352 }; 353 __le16 h_advise; 354 /* 355 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 356 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 357 */ 358 __u8 h_algorithmtype; 359 /* 360 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 361 * bit 3-6 : reserved; 362 * bit 7 : move the whole file into packed inode or not. 363 */ 364 __u8 h_clusterbits; 365}; 366 367/* 368 * On-disk logical cluster type: 369 * 0 - literal (uncompressed) lcluster 370 * 1,3 - compressed lcluster (for HEAD lclusters) 371 * 2 - compressed lcluster (for NONHEAD lclusters) 372 * 373 * In detail, 374 * 0 - literal (uncompressed) lcluster, 375 * di_advise = 0 376 * di_clusterofs = the literal data offset of the lcluster 377 * di_blkaddr = the blkaddr of the literal pcluster 378 * 379 * 1,3 - compressed lcluster (for HEAD lclusters) 380 * di_advise = 1 or 3 381 * di_clusterofs = the decompressed data offset of the lcluster 382 * di_blkaddr = the blkaddr of the compressed pcluster 383 * 384 * 2 - compressed lcluster (for NONHEAD lclusters) 385 * di_advise = 2 386 * di_clusterofs = 387 * the decompressed data offset in its own HEAD lcluster 388 * di_u.delta[0] = distance to this HEAD lcluster 389 * di_u.delta[1] = distance to the next HEAD lcluster 390 */ 391enum { 392 Z_EROFS_LCLUSTER_TYPE_PLAIN = 0, 393 Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1, 394 Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2, 395 Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3, 396 Z_EROFS_LCLUSTER_TYPE_MAX 397}; 398 399#define Z_EROFS_LI_LCLUSTER_TYPE_BITS 2 400#define Z_EROFS_LI_LCLUSTER_TYPE_BIT 0 401 402/* (noncompact only, HEAD) This pcluster refers to partial decompressed data */ 403#define Z_EROFS_LI_PARTIAL_REF (1 << 15) 404 405/* 406 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 407 * compressed block count of a compressed extent (in logical clusters, aka. 408 * block count of a pcluster). 409 */ 410#define Z_EROFS_LI_D0_CBLKCNT (1 << 11) 411 412struct z_erofs_lcluster_index { 413 __le16 di_advise; 414 /* where to decompress in the head lcluster */ 415 __le16 di_clusterofs; 416 417 union { 418 /* for the HEAD lclusters */ 419 __le32 blkaddr; 420 /* 421 * for the NONHEAD lclusters 422 * [0] - distance to its HEAD lcluster 423 * [1] - distance to the next HEAD lcluster 424 */ 425 __le16 delta[2]; 426 } di_u; 427}; 428 429#define Z_EROFS_FULL_INDEX_ALIGN(end) \ 430 (ALIGN(end, 8) + sizeof(struct z_erofs_map_header) + 8) 431 432/* check the EROFS on-disk layout strictly at compile time */ 433static inline void erofs_check_ondisk_layout_definitions(void) 434{ 435 const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) { 436 .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT 437 }; 438 439 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 440 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 441 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 442 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 443 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 444 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 445 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 446 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 447 BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8); 448 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 449 /* keep in sync between 2 index structures for better extendibility */ 450 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 451 sizeof(struct z_erofs_lcluster_index)); 452 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 453 454 BUILD_BUG_ON(BIT(Z_EROFS_LI_LCLUSTER_TYPE_BITS) < 455 Z_EROFS_LCLUSTER_TYPE_MAX - 1); 456 /* exclude old compiler versions like gcc 7.5.0 */ 457 BUILD_BUG_ON(__builtin_constant_p(fmh) ? 458 fmh != cpu_to_le64(1ULL << 63) : 0); 459} 460 461#endif 462