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_ALL_FEATURE_INCOMPAT \ 25 (EROFS_FEATURE_INCOMPAT_LZ4_0PADDING | \ 26 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \ 27 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \ 28 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE) 29 30 #define EROFS_SB_EXTSLOT_SIZE 16 31 32 /* erofs on-disk super block (currently 128 bytes) */ 33 struct erofs_super_block { 34 __le32 magic; /* file system magic number */ 35 __le32 checksum; /* crc32c(super_block) */ 36 __le32 feature_compat; 37 __u8 blkszbits; /* support block_size == PAGE_SIZE only */ 38 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ 39 40 __le16 root_nid; /* nid of root directory */ 41 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 42 43 __le64 build_time; /* inode v1 time derivation */ 44 __le32 build_time_nsec; /* inode v1 time derivation in nano scale */ 45 __le32 blocks; /* used for statfs */ 46 __le32 meta_blkaddr; /* start block address of metadata area */ 47 __le32 xattr_blkaddr; /* start block address of shared xattr area */ 48 __u8 uuid[16]; /* 128-bit uuid for volume */ 49 __u8 volume_name[16]; /* volume name */ 50 __le32 feature_incompat; 51 union { 52 /* bitmap for available compression algorithms */ 53 __le16 available_compr_algs; 54 /* customized sliding window size instead of 64k by default */ 55 __le16 lz4_max_distance; 56 } __packed u1; 57 __u8 reserved2[42]; 58 }; 59 60 /* 61 * erofs inode datalayout (i_format in on-disk inode): 62 * 0 - inode plain without inline data A: 63 * inode, [xattrs], ... | ... | no-holed data 64 * 1 - inode VLE compression B (legacy): 65 * inode, [xattrs], extents ... | ... 66 * 2 - inode plain with inline data C: 67 * inode, [xattrs], last_inline_data, ... | ... | no-holed data 68 * 3 - inode compression D: 69 * inode, [xattrs], map_header, extents ... | ... 70 * 4 - inode chunk-based E: 71 * inode, [xattrs], chunk indexes ... | ... 72 * 5~7 - reserved 73 */ 74 enum { 75 EROFS_INODE_FLAT_PLAIN = 0, 76 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, 77 EROFS_INODE_FLAT_INLINE = 2, 78 EROFS_INODE_FLAT_COMPRESSION = 3, 79 EROFS_INODE_CHUNK_BASED = 4, 80 EROFS_INODE_DATALAYOUT_MAX 81 }; 82 83 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 84 { 85 return datamode == EROFS_INODE_FLAT_COMPRESSION || 86 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; 87 } 88 89 /* bit definitions of inode i_advise */ 90 #define EROFS_I_VERSION_BITS 1 91 #define EROFS_I_DATALAYOUT_BITS 3 92 93 #define EROFS_I_VERSION_BIT 0 94 #define EROFS_I_DATALAYOUT_BIT 1 95 96 #define EROFS_I_ALL \ 97 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1) 98 99 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */ 100 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F 101 /* with chunk indexes or just a 4-byte blkaddr array */ 102 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020 103 104 #define EROFS_CHUNK_FORMAT_ALL \ 105 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES) 106 107 struct erofs_inode_chunk_info { 108 __le16 format; /* chunk blkbits, etc. */ 109 __le16 reserved; 110 }; 111 112 /* 32-byte reduced form of an ondisk inode */ 113 struct erofs_inode_compact { 114 __le16 i_format; /* inode format hints */ 115 116 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 117 __le16 i_xattr_icount; 118 __le16 i_mode; 119 __le16 i_nlink; 120 __le32 i_size; 121 __le32 i_reserved; 122 union { 123 /* file total compressed blocks for data mapping 1 */ 124 __le32 compressed_blocks; 125 __le32 raw_blkaddr; 126 127 /* for device files, used to indicate old/new device # */ 128 __le32 rdev; 129 130 /* for chunk-based files, it contains the summary info */ 131 struct erofs_inode_chunk_info c; 132 } i_u; 133 __le32 i_ino; /* only used for 32-bit stat compatibility */ 134 __le16 i_uid; 135 __le16 i_gid; 136 __le32 i_reserved2; 137 }; 138 139 /* 32 bytes on-disk inode */ 140 #define EROFS_INODE_LAYOUT_COMPACT 0 141 /* 64 bytes on-disk inode */ 142 #define EROFS_INODE_LAYOUT_EXTENDED 1 143 144 /* 64-byte complete form of an ondisk inode */ 145 struct erofs_inode_extended { 146 __le16 i_format; /* inode format hints */ 147 148 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 149 __le16 i_xattr_icount; 150 __le16 i_mode; 151 __le16 i_reserved; 152 __le64 i_size; 153 union { 154 /* file total compressed blocks for data mapping 1 */ 155 __le32 compressed_blocks; 156 __le32 raw_blkaddr; 157 158 /* for device files, used to indicate old/new device # */ 159 __le32 rdev; 160 161 /* for chunk-based files, it contains the summary info */ 162 struct erofs_inode_chunk_info c; 163 } i_u; 164 165 /* only used for 32-bit stat compatibility */ 166 __le32 i_ino; 167 168 __le32 i_uid; 169 __le32 i_gid; 170 __le64 i_ctime; 171 __le32 i_ctime_nsec; 172 __le32 i_nlink; 173 __u8 i_reserved2[16]; 174 }; 175 176 #define EROFS_MAX_SHARED_XATTRS (128) 177 /* h_shared_count between 129 ... 255 are special # */ 178 #define EROFS_SHARED_XATTR_EXTENT (255) 179 180 /* 181 * inline xattrs (n == i_xattr_icount): 182 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 183 * 12 bytes / \ 184 * / \ 185 * /-----------------------\ 186 * | erofs_xattr_entries+ | 187 * +-----------------------+ 188 * inline xattrs must starts in erofs_xattr_ibody_header, 189 * for read-only fs, no need to introduce h_refcount 190 */ 191 struct erofs_xattr_ibody_header { 192 __le32 h_reserved; 193 __u8 h_shared_count; 194 __u8 h_reserved2[7]; 195 __le32 h_shared_xattrs[0]; /* shared xattr id array */ 196 }; 197 198 /* Name indexes */ 199 #define EROFS_XATTR_INDEX_USER 1 200 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 201 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 202 #define EROFS_XATTR_INDEX_TRUSTED 4 203 #define EROFS_XATTR_INDEX_LUSTRE 5 204 #define EROFS_XATTR_INDEX_SECURITY 6 205 206 /* xattr entry (for both inline & shared xattrs) */ 207 struct erofs_xattr_entry { 208 __u8 e_name_len; /* length of name */ 209 __u8 e_name_index; /* attribute name index */ 210 __le16 e_value_size; /* size of attribute value */ 211 /* followed by e_name and e_value */ 212 char e_name[0]; /* attribute name */ 213 }; 214 215 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 216 { 217 if (!i_xattr_icount) 218 return 0; 219 220 return sizeof(struct erofs_xattr_ibody_header) + 221 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 222 } 223 224 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 225 226 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 227 { 228 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 229 e->e_name_len + le16_to_cpu(e->e_value_size)); 230 } 231 232 /* represent a zeroed chunk (hole) */ 233 #define EROFS_NULL_ADDR -1 234 235 /* 4-byte block address array */ 236 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) 237 238 /* 8-byte inode chunk indexes */ 239 struct erofs_inode_chunk_index { 240 __le16 advise; /* always 0, don't care for now */ 241 __le16 device_id; /* back-end storage id, always 0 for now */ 242 __le32 blkaddr; /* start block address of this inode chunk */ 243 }; 244 245 /* maximum supported size of a physical compression cluster */ 246 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 247 248 /* available compression algorithm types (for h_algorithmtype) */ 249 enum { 250 Z_EROFS_COMPRESSION_LZ4 = 0, 251 Z_EROFS_COMPRESSION_MAX 252 }; 253 #define Z_EROFS_ALL_COMPR_ALGS (1 << (Z_EROFS_COMPRESSION_MAX - 1)) 254 255 /* 14 bytes (+ length field = 16 bytes) */ 256 struct z_erofs_lz4_cfgs { 257 __le16 max_distance; 258 __le16 max_pclusterblks; 259 u8 reserved[10]; 260 } __packed; 261 262 /* 263 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 264 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 265 * (4B) + 2B + (4B) if compacted 2B is on. 266 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 267 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 268 */ 269 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 270 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 271 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 272 273 struct z_erofs_map_header { 274 __le32 h_reserved1; 275 __le16 h_advise; 276 /* 277 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 278 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 279 */ 280 __u8 h_algorithmtype; 281 /* 282 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 283 * bit 3-7 : reserved. 284 */ 285 __u8 h_clusterbits; 286 }; 287 288 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 289 290 /* 291 * Fixed-sized output compression ondisk Logical Extent cluster type: 292 * 0 - literal (uncompressed) cluster 293 * 1 - compressed cluster (for the head logical cluster) 294 * 2 - compressed cluster (for the other logical clusters) 295 * 296 * In detail, 297 * 0 - literal (uncompressed) cluster, 298 * di_advise = 0 299 * di_clusterofs = the literal data offset of the cluster 300 * di_blkaddr = the blkaddr of the literal cluster 301 * 302 * 1 - compressed cluster (for the head logical cluster) 303 * di_advise = 1 304 * di_clusterofs = the decompressed data offset of the cluster 305 * di_blkaddr = the blkaddr of the compressed cluster 306 * 307 * 2 - compressed cluster (for the other logical clusters) 308 * di_advise = 2 309 * di_clusterofs = 310 * the decompressed data offset in its own head cluster 311 * di_u.delta[0] = distance to its corresponding head cluster 312 * di_u.delta[1] = distance to its corresponding tail cluster 313 * (di_advise could be 0, 1 or 2) 314 */ 315 enum { 316 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 317 Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1, 318 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 319 Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3, 320 Z_EROFS_VLE_CLUSTER_TYPE_MAX 321 }; 322 323 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 324 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 325 326 /* 327 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 328 * compressed block count of a compressed extent (in logical clusters, aka. 329 * block count of a pcluster). 330 */ 331 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11) 332 333 struct z_erofs_vle_decompressed_index { 334 __le16 di_advise; 335 /* where to decompress in the head cluster */ 336 __le16 di_clusterofs; 337 338 union { 339 /* for the head cluster */ 340 __le32 blkaddr; 341 /* 342 * for the rest clusters 343 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) 344 * [0] - pointing to the head cluster 345 * [1] - pointing to the tail cluster 346 */ 347 __le16 delta[2]; 348 } di_u; 349 }; 350 351 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 352 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 353 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 354 355 /* dirent sorts in alphabet order, thus we can do binary search */ 356 struct erofs_dirent { 357 __le64 nid; /* node number */ 358 __le16 nameoff; /* start offset of file name */ 359 __u8 file_type; /* file type */ 360 __u8 reserved; /* reserved */ 361 } __packed; 362 363 /* 364 * EROFS file types should match generic FT_* types and 365 * it seems no need to add BUILD_BUG_ONs since potential 366 * unmatchness will break other fses as well... 367 */ 368 369 #define EROFS_NAME_LEN 255 370 371 /* check the EROFS on-disk layout strictly at compile time */ 372 static inline void erofs_check_ondisk_layout_definitions(void) 373 { 374 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 375 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 376 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 377 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 378 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 379 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); 380 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); 381 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 382 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 383 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 384 /* keep in sync between 2 index structures for better extendibility */ 385 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 386 sizeof(struct z_erofs_vle_decompressed_index)); 387 388 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 389 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 390 } 391 392 #endif 393