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 16 /* 17 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should 18 * be incompatible with this kernel version. 19 */ 20 #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001 21 #define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002 22 #define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002 23 #define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004 24 #define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008 25 #define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008 26 #define EROFS_ALL_FEATURE_INCOMPAT \ 27 (EROFS_FEATURE_INCOMPAT_LZ4_0PADDING | \ 28 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \ 29 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \ 30 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \ 31 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \ 32 EROFS_FEATURE_INCOMPAT_COMPR_HEAD2) 33 34 #define EROFS_SB_EXTSLOT_SIZE 16 35 36 struct erofs_deviceslot { 37 union { 38 u8 uuid[16]; /* used for device manager later */ 39 u8 userdata[64]; /* digest(sha256), etc. */ 40 } u; 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; /* inode v1 time derivation */ 59 __le32 build_time_nsec; /* inode v1 time derivation in nano 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 - inode plain without inline data A: 80 * inode, [xattrs], ... | ... | no-holed data 81 * 1 - inode VLE compression B (legacy): 82 * inode, [xattrs], extents ... | ... 83 * 2 - inode plain with inline data C: 84 * inode, [xattrs], last_inline_data, ... | ... | no-holed data 85 * 3 - inode compression D: 86 * inode, [xattrs], map_header, extents ... | ... 87 * 4 - inode chunk-based E: 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_advise */ 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 /* file total compressed blocks for data mapping 1 */ 141 __le32 compressed_blocks; 142 __le32 raw_blkaddr; 143 144 /* for device files, used to indicate old/new device # */ 145 __le32 rdev; 146 147 /* for chunk-based files, it contains the summary info */ 148 struct erofs_inode_chunk_info c; 149 } i_u; 150 __le32 i_ino; /* only used for 32-bit stat compatibility */ 151 __le16 i_uid; 152 __le16 i_gid; 153 __le32 i_reserved2; 154 }; 155 156 /* 32 bytes on-disk inode */ 157 #define EROFS_INODE_LAYOUT_COMPACT 0 158 /* 64 bytes on-disk inode */ 159 #define EROFS_INODE_LAYOUT_EXTENDED 1 160 161 /* 64-byte complete form of an ondisk inode */ 162 struct erofs_inode_extended { 163 __le16 i_format; /* inode format hints */ 164 165 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 166 __le16 i_xattr_icount; 167 __le16 i_mode; 168 __le16 i_reserved; 169 __le64 i_size; 170 union { 171 /* file total compressed blocks for data mapping 1 */ 172 __le32 compressed_blocks; 173 __le32 raw_blkaddr; 174 175 /* for device files, used to indicate old/new device # */ 176 __le32 rdev; 177 178 /* for chunk-based files, it contains the summary info */ 179 struct erofs_inode_chunk_info c; 180 } i_u; 181 182 /* only used for 32-bit stat compatibility */ 183 __le32 i_ino; 184 185 __le32 i_uid; 186 __le32 i_gid; 187 __le64 i_ctime; 188 __le32 i_ctime_nsec; 189 __le32 i_nlink; 190 __u8 i_reserved2[16]; 191 }; 192 193 #define EROFS_MAX_SHARED_XATTRS (128) 194 /* h_shared_count between 129 ... 255 are special # */ 195 #define EROFS_SHARED_XATTR_EXTENT (255) 196 197 /* 198 * inline xattrs (n == i_xattr_icount): 199 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 200 * 12 bytes / \ 201 * / \ 202 * /-----------------------\ 203 * | erofs_xattr_entries+ | 204 * +-----------------------+ 205 * inline xattrs must starts in erofs_xattr_ibody_header, 206 * for read-only fs, no need to introduce h_refcount 207 */ 208 struct erofs_xattr_ibody_header { 209 __le32 h_reserved; 210 __u8 h_shared_count; 211 __u8 h_reserved2[7]; 212 __le32 h_shared_xattrs[0]; /* shared xattr id array */ 213 }; 214 215 /* Name indexes */ 216 #define EROFS_XATTR_INDEX_USER 1 217 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 218 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 219 #define EROFS_XATTR_INDEX_TRUSTED 4 220 #define EROFS_XATTR_INDEX_LUSTRE 5 221 #define EROFS_XATTR_INDEX_SECURITY 6 222 223 /* xattr entry (for both inline & shared xattrs) */ 224 struct erofs_xattr_entry { 225 __u8 e_name_len; /* length of name */ 226 __u8 e_name_index; /* attribute name index */ 227 __le16 e_value_size; /* size of attribute value */ 228 /* followed by e_name and e_value */ 229 char e_name[0]; /* attribute name */ 230 }; 231 232 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 233 { 234 if (!i_xattr_icount) 235 return 0; 236 237 return sizeof(struct erofs_xattr_ibody_header) + 238 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 239 } 240 241 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 242 243 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 244 { 245 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 246 e->e_name_len + le16_to_cpu(e->e_value_size)); 247 } 248 249 /* represent a zeroed chunk (hole) */ 250 #define EROFS_NULL_ADDR -1 251 252 /* 4-byte block address array */ 253 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 254 255 /* 8-byte inode chunk indexes */ 256 struct erofs_inode_chunk_index { 257 __le16 advise; /* always 0, don't care for now */ 258 __le16 device_id; /* back-end storage id (with bits masked) */ 259 __le32 blkaddr; /* start block address of this inode chunk */ 260 }; 261 262 /* maximum supported size of a physical compression cluster */ 263 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 264 265 /* available compression algorithm types (for h_algorithmtype) */ 266 enum { 267 Z_EROFS_COMPRESSION_LZ4 = 0, 268 Z_EROFS_COMPRESSION_LZMA = 1, 269 Z_EROFS_COMPRESSION_MAX 270 }; 271 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) 272 273 /* 14 bytes (+ length field = 16 bytes) */ 274 struct z_erofs_lz4_cfgs { 275 __le16 max_distance; 276 __le16 max_pclusterblks; 277 u8 reserved[10]; 278 } __packed; 279 280 /* 14 bytes (+ length field = 16 bytes) */ 281 struct z_erofs_lzma_cfgs { 282 __le32 dict_size; 283 __le16 format; 284 u8 reserved[8]; 285 } __packed; 286 287 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) 288 289 /* 290 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 291 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 292 * (4B) + 2B + (4B) if compacted 2B is on. 293 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 294 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 295 */ 296 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 297 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 298 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 299 300 struct z_erofs_map_header { 301 __le32 h_reserved1; 302 __le16 h_advise; 303 /* 304 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 305 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 306 */ 307 __u8 h_algorithmtype; 308 /* 309 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 310 * bit 3-7 : reserved. 311 */ 312 __u8 h_clusterbits; 313 }; 314 315 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 316 317 /* 318 * Fixed-sized output compression on-disk logical cluster type: 319 * 0 - literal (uncompressed) lcluster 320 * 1,3 - compressed lcluster (for HEAD lclusters) 321 * 2 - compressed lcluster (for NONHEAD lclusters) 322 * 323 * In detail, 324 * 0 - literal (uncompressed) lcluster, 325 * di_advise = 0 326 * di_clusterofs = the literal data offset of the lcluster 327 * di_blkaddr = the blkaddr of the literal pcluster 328 * 329 * 1,3 - compressed lcluster (for HEAD lclusters) 330 * di_advise = 1 or 3 331 * di_clusterofs = the decompressed data offset of the lcluster 332 * di_blkaddr = the blkaddr of the compressed pcluster 333 * 334 * 2 - compressed lcluster (for NONHEAD lclusters) 335 * di_advise = 2 336 * di_clusterofs = 337 * the decompressed data offset in its own HEAD lcluster 338 * di_u.delta[0] = distance to this HEAD lcluster 339 * di_u.delta[1] = distance to the next HEAD lcluster 340 */ 341 enum { 342 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 343 Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 = 1, 344 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 345 Z_EROFS_VLE_CLUSTER_TYPE_HEAD2 = 3, 346 Z_EROFS_VLE_CLUSTER_TYPE_MAX 347 }; 348 349 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 350 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 351 352 /* 353 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 354 * compressed block count of a compressed extent (in logical clusters, aka. 355 * block count of a pcluster). 356 */ 357 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11) 358 359 struct z_erofs_vle_decompressed_index { 360 __le16 di_advise; 361 /* where to decompress in the head cluster */ 362 __le16 di_clusterofs; 363 364 union { 365 /* for the head cluster */ 366 __le32 blkaddr; 367 /* 368 * for the rest clusters 369 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) 370 * [0] - pointing to the head cluster 371 * [1] - pointing to the tail cluster 372 */ 373 __le16 delta[2]; 374 } di_u; 375 }; 376 377 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 378 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 379 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 380 381 /* dirent sorts in alphabet order, thus we can do binary search */ 382 struct erofs_dirent { 383 __le64 nid; /* node number */ 384 __le16 nameoff; /* start offset of file name */ 385 __u8 file_type; /* file type */ 386 __u8 reserved; /* reserved */ 387 } __packed; 388 389 /* 390 * EROFS file types should match generic FT_* types and 391 * it seems no need to add BUILD_BUG_ONs since potential 392 * unmatchness will break other fses as well... 393 */ 394 395 #define EROFS_NAME_LEN 255 396 397 /* check the EROFS on-disk layout strictly at compile time */ 398 static inline void erofs_check_ondisk_layout_definitions(void) 399 { 400 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 401 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 402 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 403 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 404 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 405 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 406 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 407 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 408 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 409 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 410 /* keep in sync between 2 index structures for better extendibility */ 411 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 412 sizeof(struct z_erofs_vle_decompressed_index)); 413 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); 414 415 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 416 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 417 } 418 419 #endif 420