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 u8 tag[64]; /* digest(sha256), etc. */ 41 __le32 blocks; /* total fs blocks of this device */ 42 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */ 43 u8 reserved[56]; 44 }; 45 #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot) 46 47 /* erofs on-disk super block (currently 128 bytes) */ 48 struct erofs_super_block { 49 __le32 magic; /* file system magic number */ 50 __le32 checksum; /* crc32c(super_block) */ 51 __le32 feature_compat; 52 __u8 blkszbits; /* support block_size == PAGE_SIZE only */ 53 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ 54 55 __le16 root_nid; /* nid of root directory */ 56 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 57 58 __le64 build_time; /* compact inode time derivation */ 59 __le32 build_time_nsec; /* compact inode time derivation in ns scale */ 60 __le32 blocks; /* used for statfs */ 61 __le32 meta_blkaddr; /* start block address of metadata area */ 62 __le32 xattr_blkaddr; /* start block address of shared xattr area */ 63 __u8 uuid[16]; /* 128-bit uuid for volume */ 64 __u8 volume_name[16]; /* volume name */ 65 __le32 feature_incompat; 66 union { 67 /* bitmap for available compression algorithms */ 68 __le16 available_compr_algs; 69 /* customized sliding window size instead of 64k by default */ 70 __le16 lz4_max_distance; 71 } __packed u1; 72 __le16 extra_devices; /* # of devices besides the primary device */ 73 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */ 74 __u8 reserved2[38]; 75 }; 76 77 /* 78 * erofs inode datalayout (i_format in on-disk inode): 79 * 0 - uncompressed flat inode without tail-packing inline data: 80 * inode, [xattrs], ... | ... | no-holed data 81 * 1 - compressed inode with non-compact indexes: 82 * inode, [xattrs], [map_header], extents ... | ... 83 * 2 - uncompressed flat inode with tail-packing inline data: 84 * inode, [xattrs], tailpacking data, ... | ... | no-holed data 85 * 3 - compressed inode with compact indexes: 86 * inode, [xattrs], map_header, extents ... | ... 87 * 4 - chunk-based inode with (optional) multi-device support: 88 * inode, [xattrs], chunk indexes ... | ... 89 * 5~7 - reserved 90 */ 91 enum { 92 EROFS_INODE_FLAT_PLAIN = 0, 93 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, 94 EROFS_INODE_FLAT_INLINE = 2, 95 EROFS_INODE_FLAT_COMPRESSION = 3, 96 EROFS_INODE_CHUNK_BASED = 4, 97 EROFS_INODE_DATALAYOUT_MAX 98 }; 99 100 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 101 { 102 return datamode == EROFS_INODE_FLAT_COMPRESSION || 103 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; 104 } 105 106 /* bit definitions of inode i_format */ 107 #define EROFS_I_VERSION_BITS 1 108 #define EROFS_I_DATALAYOUT_BITS 3 109 110 #define EROFS_I_VERSION_BIT 0 111 #define EROFS_I_DATALAYOUT_BIT 1 112 113 #define EROFS_I_ALL \ 114 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1) 115 116 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */ 117 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F 118 /* with chunk indexes or just a 4-byte blkaddr array */ 119 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020 120 121 #define EROFS_CHUNK_FORMAT_ALL \ 122 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES) 123 124 struct erofs_inode_chunk_info { 125 __le16 format; /* chunk blkbits, etc. */ 126 __le16 reserved; 127 }; 128 129 /* 32-byte reduced form of an ondisk inode */ 130 struct erofs_inode_compact { 131 __le16 i_format; /* inode format hints */ 132 133 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 134 __le16 i_xattr_icount; 135 __le16 i_mode; 136 __le16 i_nlink; 137 __le32 i_size; 138 __le32 i_reserved; 139 union { 140 /* total compressed blocks for compressed inodes */ 141 __le32 compressed_blocks; 142 /* block address for uncompressed flat inodes */ 143 __le32 raw_blkaddr; 144 145 /* for device files, used to indicate old/new device # */ 146 __le32 rdev; 147 148 /* for chunk-based files, it contains the summary info */ 149 struct erofs_inode_chunk_info c; 150 } i_u; 151 __le32 i_ino; /* only used for 32-bit stat compatibility */ 152 __le16 i_uid; 153 __le16 i_gid; 154 __le32 i_reserved2; 155 }; 156 157 /* 32-byte on-disk inode */ 158 #define EROFS_INODE_LAYOUT_COMPACT 0 159 /* 64-byte on-disk inode */ 160 #define EROFS_INODE_LAYOUT_EXTENDED 1 161 162 /* 64-byte complete form of an ondisk inode */ 163 struct erofs_inode_extended { 164 __le16 i_format; /* inode format hints */ 165 166 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 167 __le16 i_xattr_icount; 168 __le16 i_mode; 169 __le16 i_reserved; 170 __le64 i_size; 171 union { 172 /* total compressed blocks for compressed inodes */ 173 __le32 compressed_blocks; 174 /* block address for uncompressed flat inodes */ 175 __le32 raw_blkaddr; 176 177 /* for device files, used to indicate old/new device # */ 178 __le32 rdev; 179 180 /* for chunk-based files, it contains the summary info */ 181 struct erofs_inode_chunk_info c; 182 } i_u; 183 184 /* only used for 32-bit stat compatibility */ 185 __le32 i_ino; 186 187 __le32 i_uid; 188 __le32 i_gid; 189 __le64 i_mtime; 190 __le32 i_mtime_nsec; 191 __le32 i_nlink; 192 __u8 i_reserved2[16]; 193 }; 194 195 #define EROFS_MAX_SHARED_XATTRS (128) 196 /* h_shared_count between 129 ... 255 are special # */ 197 #define EROFS_SHARED_XATTR_EXTENT (255) 198 199 /* 200 * inline xattrs (n == i_xattr_icount): 201 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 202 * 12 bytes / \ 203 * / \ 204 * /-----------------------\ 205 * | erofs_xattr_entries+ | 206 * +-----------------------+ 207 * inline xattrs must starts in erofs_xattr_ibody_header, 208 * for read-only fs, no need to introduce h_refcount 209 */ 210 struct erofs_xattr_ibody_header { 211 __le32 h_reserved; 212 __u8 h_shared_count; 213 __u8 h_reserved2[7]; 214 __le32 h_shared_xattrs[]; /* shared xattr id array */ 215 }; 216 217 /* Name indexes */ 218 #define EROFS_XATTR_INDEX_USER 1 219 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 220 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 221 #define EROFS_XATTR_INDEX_TRUSTED 4 222 #define EROFS_XATTR_INDEX_LUSTRE 5 223 #define EROFS_XATTR_INDEX_SECURITY 6 224 225 /* xattr entry (for both inline & shared xattrs) */ 226 struct erofs_xattr_entry { 227 __u8 e_name_len; /* length of name */ 228 __u8 e_name_index; /* attribute name index */ 229 __le16 e_value_size; /* size of attribute value */ 230 /* followed by e_name and e_value */ 231 char e_name[]; /* attribute name */ 232 }; 233 234 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 235 { 236 if (!i_xattr_icount) 237 return 0; 238 239 return sizeof(struct erofs_xattr_ibody_header) + 240 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 241 } 242 243 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 244 245 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 246 { 247 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 248 e->e_name_len + le16_to_cpu(e->e_value_size)); 249 } 250 251 /* represent a zeroed chunk (hole) */ 252 #define EROFS_NULL_ADDR -1 253 254 /* 4-byte block address array */ 255 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 256 257 /* 8-byte inode chunk indexes */ 258 struct erofs_inode_chunk_index { 259 __le16 advise; /* always 0, don't care for now */ 260 __le16 device_id; /* back-end storage id (with bits masked) */ 261 __le32 blkaddr; /* start block address of this inode chunk */ 262 }; 263 264 /* maximum supported size of a physical compression cluster */ 265 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 266 267 /* available compression algorithm types (for h_algorithmtype) */ 268 enum { 269 Z_EROFS_COMPRESSION_LZ4 = 0, 270 Z_EROFS_COMPRESSION_LZMA = 1, 271 Z_EROFS_COMPRESSION_MAX 272 }; 273 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 274 275 /* 14 bytes (+ length field = 16 bytes) */ 276 struct z_erofs_lz4_cfgs { 277 __le16 max_distance; 278 __le16 max_pclusterblks; 279 u8 reserved[10]; 280 } __packed; 281 282 /* 14 bytes (+ length field = 16 bytes) */ 283 struct z_erofs_lzma_cfgs { 284 __le32 dict_size; 285 __le16 format; 286 u8 reserved[8]; 287 } __packed; 288 289 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 290 291 /* 292 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 293 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 294 * (4B) + 2B + (4B) if compacted 2B is on. 295 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 296 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 297 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) 298 */ 299 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 300 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 301 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 302 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 303 304 struct z_erofs_map_header { 305 __le16 h_reserved1; 306 /* indicates the encoded size of tailpacking data */ 307 __le16 h_idata_size; 308 __le16 h_advise; 309 /* 310 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 311 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 312 */ 313 __u8 h_algorithmtype; 314 /* 315 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 316 * bit 3-7 : reserved. 317 */ 318 __u8 h_clusterbits; 319 }; 320 321 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 322 323 /* 324 * Fixed-sized output compression on-disk logical cluster type: 325 * 0 - literal (uncompressed) lcluster 326 * 1,3 - compressed lcluster (for HEAD lclusters) 327 * 2 - compressed lcluster (for NONHEAD lclusters) 328 * 329 * In detail, 330 * 0 - literal (uncompressed) lcluster, 331 * di_advise = 0 332 * di_clusterofs = the literal data offset of the lcluster 333 * di_blkaddr = the blkaddr of the literal pcluster 334 * 335 * 1,3 - compressed lcluster (for HEAD lclusters) 336 * di_advise = 1 or 3 337 * di_clusterofs = the decompressed data offset of the lcluster 338 * di_blkaddr = the blkaddr of the compressed pcluster 339 * 340 * 2 - compressed lcluster (for NONHEAD lclusters) 341 * di_advise = 2 342 * di_clusterofs = 343 * the decompressed data offset in its own HEAD lcluster 344 * di_u.delta[0] = distance to this HEAD lcluster 345 * di_u.delta[1] = distance to the next HEAD lcluster 346 */ 347 enum { 348 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 349 Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 = 1, 350 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 351 Z_EROFS_VLE_CLUSTER_TYPE_HEAD2 = 3, 352 Z_EROFS_VLE_CLUSTER_TYPE_MAX 353 }; 354 355 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 356 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 357 358 /* 359 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 360 * compressed block count of a compressed extent (in logical clusters, aka. 361 * block count of a pcluster). 362 */ 363 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11) 364 365 struct z_erofs_vle_decompressed_index { 366 __le16 di_advise; 367 /* where to decompress in the head lcluster */ 368 __le16 di_clusterofs; 369 370 union { 371 /* for the HEAD lclusters */ 372 __le32 blkaddr; 373 /* 374 * for the NONHEAD lclusters 375 * [0] - distance to its HEAD lcluster 376 * [1] - distance to the next HEAD lcluster 377 */ 378 __le16 delta[2]; 379 } di_u; 380 }; 381 382 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 383 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 384 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 385 386 /* dirent sorts in alphabet order, thus we can do binary search */ 387 struct erofs_dirent { 388 __le64 nid; /* node number */ 389 __le16 nameoff; /* start offset of file name */ 390 __u8 file_type; /* file type */ 391 __u8 reserved; /* reserved */ 392 } __packed; 393 394 /* 395 * EROFS file types should match generic FT_* types and 396 * it seems no need to add BUILD_BUG_ONs since potential 397 * unmatchness will break other fses as well... 398 */ 399 400 #define EROFS_NAME_LEN 255 401 402 /* check the EROFS on-disk layout strictly at compile time */ 403 static inline void erofs_check_ondisk_layout_definitions(void) 404 { 405 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 406 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 407 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 408 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 409 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 410 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 411 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 412 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 413 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 414 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 415 /* keep in sync between 2 index structures for better extendibility */ 416 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 417 sizeof(struct z_erofs_vle_decompressed_index)); 418 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 419 420 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 421 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 422 } 423 424 #endif 425