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_ALL_FEATURE_INCOMPAT \ 29 (EROFS_FEATURE_INCOMPAT_ZERO_PADDING | \ 30 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \ 31 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \ 32 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \ 33 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \ 34 EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 | \ 35 EROFS_FEATURE_INCOMPAT_ZTAILPACKING) 36 37 #define EROFS_SB_EXTSLOT_SIZE 16 38 39 struct erofs_deviceslot { 40 union { 41 u8 uuid[16]; /* used for device manager later */ 42 u8 userdata[64]; /* digest(sha256), etc. */ 43 } u; 44 __le32 blocks; /* total fs blocks of this device */ 45 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */ 46 u8 reserved[56]; 47 }; 48 #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot) 49 50 /* erofs on-disk super block (currently 128 bytes) */ 51 struct erofs_super_block { 52 __le32 magic; /* file system magic number */ 53 __le32 checksum; /* crc32c(super_block) */ 54 __le32 feature_compat; 55 __u8 blkszbits; /* support block_size == PAGE_SIZE only */ 56 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ 57 58 __le16 root_nid; /* nid of root directory */ 59 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 60 61 __le64 build_time; /* compact inode time derivation */ 62 __le32 build_time_nsec; /* compact inode time derivation in ns scale */ 63 __le32 blocks; /* used for statfs */ 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 reserved2[38]; 78 }; 79 80 /* 81 * erofs inode datalayout (i_format in on-disk inode): 82 * 0 - uncompressed flat inode without tail-packing inline data: 83 * inode, [xattrs], ... | ... | no-holed data 84 * 1 - compressed inode with non-compact indexes: 85 * inode, [xattrs], [map_header], extents ... | ... 86 * 2 - uncompressed flat inode with tail-packing inline data: 87 * inode, [xattrs], tailpacking data, ... | ... | no-holed data 88 * 3 - compressed inode with compact indexes: 89 * inode, [xattrs], map_header, extents ... | ... 90 * 4 - chunk-based inode with (optional) multi-device support: 91 * inode, [xattrs], chunk indexes ... | ... 92 * 5~7 - reserved 93 */ 94 enum { 95 EROFS_INODE_FLAT_PLAIN = 0, 96 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, 97 EROFS_INODE_FLAT_INLINE = 2, 98 EROFS_INODE_FLAT_COMPRESSION = 3, 99 EROFS_INODE_CHUNK_BASED = 4, 100 EROFS_INODE_DATALAYOUT_MAX 101 }; 102 103 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 104 { 105 return datamode == EROFS_INODE_FLAT_COMPRESSION || 106 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; 107 } 108 109 /* bit definitions of inode i_format */ 110 #define EROFS_I_VERSION_BITS 1 111 #define EROFS_I_DATALAYOUT_BITS 3 112 113 #define EROFS_I_VERSION_BIT 0 114 #define EROFS_I_DATALAYOUT_BIT 1 115 116 #define EROFS_I_ALL \ 117 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1) 118 119 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */ 120 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F 121 /* with chunk indexes or just a 4-byte blkaddr array */ 122 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020 123 124 #define EROFS_CHUNK_FORMAT_ALL \ 125 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES) 126 127 struct erofs_inode_chunk_info { 128 __le16 format; /* chunk blkbits, etc. */ 129 __le16 reserved; 130 }; 131 132 /* 32-byte reduced form of an ondisk inode */ 133 struct erofs_inode_compact { 134 __le16 i_format; /* inode format hints */ 135 136 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 137 __le16 i_xattr_icount; 138 __le16 i_mode; 139 __le16 i_nlink; 140 __le32 i_size; 141 __le32 i_reserved; 142 union { 143 /* total compressed blocks for compressed inodes */ 144 __le32 compressed_blocks; 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 } i_u; 154 __le32 i_ino; /* only used for 32-bit stat compatibility */ 155 __le16 i_uid; 156 __le16 i_gid; 157 __le32 i_reserved2; 158 }; 159 160 /* 32-byte on-disk inode */ 161 #define EROFS_INODE_LAYOUT_COMPACT 0 162 /* 64-byte on-disk inode */ 163 #define EROFS_INODE_LAYOUT_EXTENDED 1 164 165 /* 64-byte complete form of an ondisk inode */ 166 struct erofs_inode_extended { 167 __le16 i_format; /* inode format hints */ 168 169 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 170 __le16 i_xattr_icount; 171 __le16 i_mode; 172 __le16 i_reserved; 173 __le64 i_size; 174 union { 175 /* total compressed blocks for compressed inodes */ 176 __le32 compressed_blocks; 177 /* block address for uncompressed flat inodes */ 178 __le32 raw_blkaddr; 179 180 /* for device files, used to indicate old/new device # */ 181 __le32 rdev; 182 183 /* for chunk-based files, it contains the summary info */ 184 struct erofs_inode_chunk_info c; 185 } i_u; 186 187 /* only used for 32-bit stat compatibility */ 188 __le32 i_ino; 189 190 __le32 i_uid; 191 __le32 i_gid; 192 __le64 i_mtime; 193 __le32 i_mtime_nsec; 194 __le32 i_nlink; 195 __u8 i_reserved2[16]; 196 }; 197 198 #define EROFS_MAX_SHARED_XATTRS (128) 199 /* h_shared_count between 129 ... 255 are special # */ 200 #define EROFS_SHARED_XATTR_EXTENT (255) 201 202 /* 203 * inline xattrs (n == i_xattr_icount): 204 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 205 * 12 bytes / \ 206 * / \ 207 * /-----------------------\ 208 * | erofs_xattr_entries+ | 209 * +-----------------------+ 210 * inline xattrs must starts in erofs_xattr_ibody_header, 211 * for read-only fs, no need to introduce h_refcount 212 */ 213 struct erofs_xattr_ibody_header { 214 __le32 h_reserved; 215 __u8 h_shared_count; 216 __u8 h_reserved2[7]; 217 __le32 h_shared_xattrs[]; /* shared xattr id array */ 218 }; 219 220 /* Name indexes */ 221 #define EROFS_XATTR_INDEX_USER 1 222 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 223 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 224 #define EROFS_XATTR_INDEX_TRUSTED 4 225 #define EROFS_XATTR_INDEX_LUSTRE 5 226 #define EROFS_XATTR_INDEX_SECURITY 6 227 228 /* xattr entry (for both inline & shared xattrs) */ 229 struct erofs_xattr_entry { 230 __u8 e_name_len; /* length of name */ 231 __u8 e_name_index; /* attribute name index */ 232 __le16 e_value_size; /* size of attribute value */ 233 /* followed by e_name and e_value */ 234 char e_name[]; /* attribute name */ 235 }; 236 237 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 238 { 239 if (!i_xattr_icount) 240 return 0; 241 242 return sizeof(struct erofs_xattr_ibody_header) + 243 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 244 } 245 246 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 247 248 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 249 { 250 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 251 e->e_name_len + le16_to_cpu(e->e_value_size)); 252 } 253 254 /* represent a zeroed chunk (hole) */ 255 #define EROFS_NULL_ADDR -1 256 257 /* 4-byte block address array */ 258 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 259 260 /* 8-byte inode chunk indexes */ 261 struct erofs_inode_chunk_index { 262 __le16 advise; /* always 0, don't care for now */ 263 __le16 device_id; /* back-end storage id (with bits masked) */ 264 __le32 blkaddr; /* start block address of this inode chunk */ 265 }; 266 267 /* maximum supported size of a physical compression cluster */ 268 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 269 270 /* available compression algorithm types (for h_algorithmtype) */ 271 enum { 272 Z_EROFS_COMPRESSION_LZ4 = 0, 273 Z_EROFS_COMPRESSION_LZMA = 1, 274 Z_EROFS_COMPRESSION_MAX 275 }; 276 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 277 278 /* 14 bytes (+ length field = 16 bytes) */ 279 struct z_erofs_lz4_cfgs { 280 __le16 max_distance; 281 __le16 max_pclusterblks; 282 u8 reserved[10]; 283 } __packed; 284 285 /* 14 bytes (+ length field = 16 bytes) */ 286 struct z_erofs_lzma_cfgs { 287 __le32 dict_size; 288 __le16 format; 289 u8 reserved[8]; 290 } __packed; 291 292 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 293 294 /* 295 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 296 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 297 * (4B) + 2B + (4B) if compacted 2B is on. 298 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 299 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 300 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) 301 */ 302 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 303 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 304 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 305 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 306 307 struct z_erofs_map_header { 308 __le16 h_reserved1; 309 /* indicates the encoded size of tailpacking data */ 310 __le16 h_idata_size; 311 __le16 h_advise; 312 /* 313 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 314 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 315 */ 316 __u8 h_algorithmtype; 317 /* 318 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 319 * bit 3-7 : reserved. 320 */ 321 __u8 h_clusterbits; 322 }; 323 324 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 325 326 /* 327 * Fixed-sized output compression on-disk logical cluster type: 328 * 0 - literal (uncompressed) lcluster 329 * 1,3 - compressed lcluster (for HEAD lclusters) 330 * 2 - compressed lcluster (for NONHEAD lclusters) 331 * 332 * In detail, 333 * 0 - literal (uncompressed) lcluster, 334 * di_advise = 0 335 * di_clusterofs = the literal data offset of the lcluster 336 * di_blkaddr = the blkaddr of the literal pcluster 337 * 338 * 1,3 - compressed lcluster (for HEAD lclusters) 339 * di_advise = 1 or 3 340 * di_clusterofs = the decompressed data offset of the lcluster 341 * di_blkaddr = the blkaddr of the compressed pcluster 342 * 343 * 2 - compressed lcluster (for NONHEAD lclusters) 344 * di_advise = 2 345 * di_clusterofs = 346 * the decompressed data offset in its own HEAD lcluster 347 * di_u.delta[0] = distance to this HEAD lcluster 348 * di_u.delta[1] = distance to the next HEAD lcluster 349 */ 350 enum { 351 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 352 Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 = 1, 353 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 354 Z_EROFS_VLE_CLUSTER_TYPE_HEAD2 = 3, 355 Z_EROFS_VLE_CLUSTER_TYPE_MAX 356 }; 357 358 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 359 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 360 361 /* 362 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 363 * compressed block count of a compressed extent (in logical clusters, aka. 364 * block count of a pcluster). 365 */ 366 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11) 367 368 struct z_erofs_vle_decompressed_index { 369 __le16 di_advise; 370 /* where to decompress in the head lcluster */ 371 __le16 di_clusterofs; 372 373 union { 374 /* for the HEAD lclusters */ 375 __le32 blkaddr; 376 /* 377 * for the NONHEAD lclusters 378 * [0] - distance to its HEAD lcluster 379 * [1] - distance to the next HEAD lcluster 380 */ 381 __le16 delta[2]; 382 } di_u; 383 }; 384 385 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 386 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 387 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 388 389 /* dirent sorts in alphabet order, thus we can do binary search */ 390 struct erofs_dirent { 391 __le64 nid; /* node number */ 392 __le16 nameoff; /* start offset of file name */ 393 __u8 file_type; /* file type */ 394 __u8 reserved; /* reserved */ 395 } __packed; 396 397 /* 398 * EROFS file types should match generic FT_* types and 399 * it seems no need to add BUILD_BUG_ONs since potential 400 * unmatchness will break other fses as well... 401 */ 402 403 #define EROFS_NAME_LEN 255 404 405 /* check the EROFS on-disk layout strictly at compile time */ 406 static inline void erofs_check_ondisk_layout_definitions(void) 407 { 408 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 409 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 410 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 411 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 412 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 413 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 414 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 415 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 416 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 417 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 418 /* keep in sync between 2 index structures for better extendibility */ 419 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 420 sizeof(struct z_erofs_vle_decompressed_index)); 421 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 422 423 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 424 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 425 } 426 427 #endif 428