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; /* inode v1 time derivation */ 62 __le32 build_time_nsec; /* inode v1 time derivation in nano 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 - inode plain without inline data A: 83 * inode, [xattrs], ... | ... | no-holed data 84 * 1 - inode VLE compression B (legacy): 85 * inode, [xattrs], extents ... | ... 86 * 2 - inode plain with inline data C: 87 * inode, [xattrs], last_inline_data, ... | ... | no-holed data 88 * 3 - inode compression D: 89 * inode, [xattrs], map_header, extents ... | ... 90 * 4 - inode chunk-based E: 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_advise */ 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 /* file total compressed blocks for data mapping 1 */ 144 __le32 compressed_blocks; 145 __le32 raw_blkaddr; 146 147 /* for device files, used to indicate old/new device # */ 148 __le32 rdev; 149 150 /* for chunk-based files, it contains the summary info */ 151 struct erofs_inode_chunk_info c; 152 } i_u; 153 __le32 i_ino; /* only used for 32-bit stat compatibility */ 154 __le16 i_uid; 155 __le16 i_gid; 156 __le32 i_reserved2; 157 }; 158 159 /* 32 bytes on-disk inode */ 160 #define EROFS_INODE_LAYOUT_COMPACT 0 161 /* 64 bytes on-disk inode */ 162 #define EROFS_INODE_LAYOUT_EXTENDED 1 163 164 /* 64-byte complete form of an ondisk inode */ 165 struct erofs_inode_extended { 166 __le16 i_format; /* inode format hints */ 167 168 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 169 __le16 i_xattr_icount; 170 __le16 i_mode; 171 __le16 i_reserved; 172 __le64 i_size; 173 union { 174 /* file total compressed blocks for data mapping 1 */ 175 __le32 compressed_blocks; 176 __le32 raw_blkaddr; 177 178 /* for device files, used to indicate old/new device # */ 179 __le32 rdev; 180 181 /* for chunk-based files, it contains the summary info */ 182 struct erofs_inode_chunk_info c; 183 } i_u; 184 185 /* only used for 32-bit stat compatibility */ 186 __le32 i_ino; 187 188 __le32 i_uid; 189 __le32 i_gid; 190 __le64 i_mtime; 191 __le32 i_mtime_nsec; 192 __le32 i_nlink; 193 __u8 i_reserved2[16]; 194 }; 195 196 #define EROFS_MAX_SHARED_XATTRS (128) 197 /* h_shared_count between 129 ... 255 are special # */ 198 #define EROFS_SHARED_XATTR_EXTENT (255) 199 200 /* 201 * inline xattrs (n == i_xattr_icount): 202 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 203 * 12 bytes / \ 204 * / \ 205 * /-----------------------\ 206 * | erofs_xattr_entries+ | 207 * +-----------------------+ 208 * inline xattrs must starts in erofs_xattr_ibody_header, 209 * for read-only fs, no need to introduce h_refcount 210 */ 211 struct erofs_xattr_ibody_header { 212 __le32 h_reserved; 213 __u8 h_shared_count; 214 __u8 h_reserved2[7]; 215 __le32 h_shared_xattrs[]; /* shared xattr id array */ 216 }; 217 218 /* Name indexes */ 219 #define EROFS_XATTR_INDEX_USER 1 220 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 221 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 222 #define EROFS_XATTR_INDEX_TRUSTED 4 223 #define EROFS_XATTR_INDEX_LUSTRE 5 224 #define EROFS_XATTR_INDEX_SECURITY 6 225 226 /* xattr entry (for both inline & shared xattrs) */ 227 struct erofs_xattr_entry { 228 __u8 e_name_len; /* length of name */ 229 __u8 e_name_index; /* attribute name index */ 230 __le16 e_value_size; /* size of attribute value */ 231 /* followed by e_name and e_value */ 232 char e_name[]; /* attribute name */ 233 }; 234 235 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 236 { 237 if (!i_xattr_icount) 238 return 0; 239 240 return sizeof(struct erofs_xattr_ibody_header) + 241 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 242 } 243 244 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 245 246 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 247 { 248 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 249 e->e_name_len + le16_to_cpu(e->e_value_size)); 250 } 251 252 /* represent a zeroed chunk (hole) */ 253 #define EROFS_NULL_ADDR -1 254 255 /* 4-byte block address array */ 256 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 257 258 /* 8-byte inode chunk indexes */ 259 struct erofs_inode_chunk_index { 260 __le16 advise; /* always 0, don't care for now */ 261 __le16 device_id; /* back-end storage id (with bits masked) */ 262 __le32 blkaddr; /* start block address of this inode chunk */ 263 }; 264 265 /* maximum supported size of a physical compression cluster */ 266 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 267 268 /* available compression algorithm types (for h_algorithmtype) */ 269 enum { 270 Z_EROFS_COMPRESSION_LZ4 = 0, 271 Z_EROFS_COMPRESSION_LZMA = 1, 272 Z_EROFS_COMPRESSION_MAX 273 }; 274 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 275 276 /* 14 bytes (+ length field = 16 bytes) */ 277 struct z_erofs_lz4_cfgs { 278 __le16 max_distance; 279 __le16 max_pclusterblks; 280 u8 reserved[10]; 281 } __packed; 282 283 /* 14 bytes (+ length field = 16 bytes) */ 284 struct z_erofs_lzma_cfgs { 285 __le32 dict_size; 286 __le16 format; 287 u8 reserved[8]; 288 } __packed; 289 290 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 291 292 /* 293 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 294 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 295 * (4B) + 2B + (4B) if compacted 2B is on. 296 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 297 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 298 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) 299 */ 300 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 301 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 302 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 303 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 304 305 struct z_erofs_map_header { 306 __le16 h_reserved1; 307 /* indicates the encoded size of tailpacking data */ 308 __le16 h_idata_size; 309 __le16 h_advise; 310 /* 311 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 312 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 313 */ 314 __u8 h_algorithmtype; 315 /* 316 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 317 * bit 3-7 : reserved. 318 */ 319 __u8 h_clusterbits; 320 }; 321 322 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 323 324 /* 325 * Fixed-sized output compression on-disk logical cluster type: 326 * 0 - literal (uncompressed) lcluster 327 * 1,3 - compressed lcluster (for HEAD lclusters) 328 * 2 - compressed lcluster (for NONHEAD lclusters) 329 * 330 * In detail, 331 * 0 - literal (uncompressed) lcluster, 332 * di_advise = 0 333 * di_clusterofs = the literal data offset of the lcluster 334 * di_blkaddr = the blkaddr of the literal pcluster 335 * 336 * 1,3 - compressed lcluster (for HEAD lclusters) 337 * di_advise = 1 or 3 338 * di_clusterofs = the decompressed data offset of the lcluster 339 * di_blkaddr = the blkaddr of the compressed pcluster 340 * 341 * 2 - compressed lcluster (for NONHEAD lclusters) 342 * di_advise = 2 343 * di_clusterofs = 344 * the decompressed data offset in its own HEAD lcluster 345 * di_u.delta[0] = distance to this HEAD lcluster 346 * di_u.delta[1] = distance to the next HEAD lcluster 347 */ 348 enum { 349 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 350 Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 = 1, 351 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 352 Z_EROFS_VLE_CLUSTER_TYPE_HEAD2 = 3, 353 Z_EROFS_VLE_CLUSTER_TYPE_MAX 354 }; 355 356 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 357 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 358 359 /* 360 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 361 * compressed block count of a compressed extent (in logical clusters, aka. 362 * block count of a pcluster). 363 */ 364 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11) 365 366 struct z_erofs_vle_decompressed_index { 367 __le16 di_advise; 368 /* where to decompress in the head cluster */ 369 __le16 di_clusterofs; 370 371 union { 372 /* for the head cluster */ 373 __le32 blkaddr; 374 /* 375 * for the rest clusters 376 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) 377 * [0] - pointing to the head cluster 378 * [1] - pointing to the tail cluster 379 */ 380 __le16 delta[2]; 381 } di_u; 382 }; 383 384 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 385 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 386 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 387 388 /* dirent sorts in alphabet order, thus we can do binary search */ 389 struct erofs_dirent { 390 __le64 nid; /* node number */ 391 __le16 nameoff; /* start offset of file name */ 392 __u8 file_type; /* file type */ 393 __u8 reserved; /* reserved */ 394 } __packed; 395 396 /* 397 * EROFS file types should match generic FT_* types and 398 * it seems no need to add BUILD_BUG_ONs since potential 399 * unmatchness will break other fses as well... 400 */ 401 402 #define EROFS_NAME_LEN 255 403 404 /* check the EROFS on-disk layout strictly at compile time */ 405 static inline void erofs_check_ondisk_layout_definitions(void) 406 { 407 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 408 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 409 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 410 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 411 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 412 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 413 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 414 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 415 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 416 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 417 /* keep in sync between 2 index structures for better extendibility */ 418 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 419 sizeof(struct z_erofs_vle_decompressed_index)); 420 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 421 422 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 423 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 424 } 425 426 #endif 427