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 * Created by Gao Xiang <gaoxiang25@huawei.com> 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_ALL_FEATURE_INCOMPAT \ 24 (EROFS_FEATURE_INCOMPAT_LZ4_0PADDING | \ 25 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \ 26 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER) 27 28 #define EROFS_SB_EXTSLOT_SIZE 16 29 30 /* erofs on-disk super block (currently 128 bytes) */ 31 struct erofs_super_block { 32 __le32 magic; /* file system magic number */ 33 __le32 checksum; /* crc32c(super_block) */ 34 __le32 feature_compat; 35 __u8 blkszbits; /* support block_size == PAGE_SIZE only */ 36 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ 37 38 __le16 root_nid; /* nid of root directory */ 39 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 40 41 __le64 build_time; /* inode v1 time derivation */ 42 __le32 build_time_nsec; /* inode v1 time derivation in nano scale */ 43 __le32 blocks; /* used for statfs */ 44 __le32 meta_blkaddr; /* start block address of metadata area */ 45 __le32 xattr_blkaddr; /* start block address of shared xattr area */ 46 __u8 uuid[16]; /* 128-bit uuid for volume */ 47 __u8 volume_name[16]; /* volume name */ 48 __le32 feature_incompat; 49 union { 50 /* bitmap for available compression algorithms */ 51 __le16 available_compr_algs; 52 /* customized sliding window size instead of 64k by default */ 53 __le16 lz4_max_distance; 54 } __packed u1; 55 __u8 reserved2[42]; 56 }; 57 58 /* 59 * erofs inode datalayout (i_format in on-disk inode): 60 * 0 - inode plain without inline data A: 61 * inode, [xattrs], ... | ... | no-holed data 62 * 1 - inode VLE compression B (legacy): 63 * inode, [xattrs], extents ... | ... 64 * 2 - inode plain with inline data C: 65 * inode, [xattrs], last_inline_data, ... | ... | no-holed data 66 * 3 - inode compression D: 67 * inode, [xattrs], map_header, extents ... | ... 68 * 4~7 - reserved 69 */ 70 enum { 71 EROFS_INODE_FLAT_PLAIN = 0, 72 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, 73 EROFS_INODE_FLAT_INLINE = 2, 74 EROFS_INODE_FLAT_COMPRESSION = 3, 75 EROFS_INODE_DATALAYOUT_MAX 76 }; 77 78 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 79 { 80 return datamode == EROFS_INODE_FLAT_COMPRESSION || 81 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; 82 } 83 84 /* bit definitions of inode i_advise */ 85 #define EROFS_I_VERSION_BITS 1 86 #define EROFS_I_DATALAYOUT_BITS 3 87 88 #define EROFS_I_VERSION_BIT 0 89 #define EROFS_I_DATALAYOUT_BIT 1 90 91 #define EROFS_I_ALL \ 92 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1) 93 94 /* 32-byte reduced form of an ondisk inode */ 95 struct erofs_inode_compact { 96 __le16 i_format; /* inode format hints */ 97 98 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 99 __le16 i_xattr_icount; 100 __le16 i_mode; 101 __le16 i_nlink; 102 __le32 i_size; 103 __le32 i_reserved; 104 union { 105 /* file total compressed blocks for data mapping 1 */ 106 __le32 compressed_blocks; 107 __le32 raw_blkaddr; 108 109 /* for device files, used to indicate old/new device # */ 110 __le32 rdev; 111 } i_u; 112 __le32 i_ino; /* only used for 32-bit stat compatibility */ 113 __le16 i_uid; 114 __le16 i_gid; 115 __le32 i_reserved2; 116 }; 117 118 /* 32 bytes on-disk inode */ 119 #define EROFS_INODE_LAYOUT_COMPACT 0 120 /* 64 bytes on-disk inode */ 121 #define EROFS_INODE_LAYOUT_EXTENDED 1 122 123 /* 64-byte complete form of an ondisk inode */ 124 struct erofs_inode_extended { 125 __le16 i_format; /* inode format hints */ 126 127 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 128 __le16 i_xattr_icount; 129 __le16 i_mode; 130 __le16 i_reserved; 131 __le64 i_size; 132 union { 133 /* file total compressed blocks for data mapping 1 */ 134 __le32 compressed_blocks; 135 __le32 raw_blkaddr; 136 137 /* for device files, used to indicate old/new device # */ 138 __le32 rdev; 139 } i_u; 140 141 /* only used for 32-bit stat compatibility */ 142 __le32 i_ino; 143 144 __le32 i_uid; 145 __le32 i_gid; 146 __le64 i_ctime; 147 __le32 i_ctime_nsec; 148 __le32 i_nlink; 149 __u8 i_reserved2[16]; 150 }; 151 152 #define EROFS_MAX_SHARED_XATTRS (128) 153 /* h_shared_count between 129 ... 255 are special # */ 154 #define EROFS_SHARED_XATTR_EXTENT (255) 155 156 /* 157 * inline xattrs (n == i_xattr_icount): 158 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 159 * 12 bytes / \ 160 * / \ 161 * /-----------------------\ 162 * | erofs_xattr_entries+ | 163 * +-----------------------+ 164 * inline xattrs must starts in erofs_xattr_ibody_header, 165 * for read-only fs, no need to introduce h_refcount 166 */ 167 struct erofs_xattr_ibody_header { 168 __le32 h_reserved; 169 __u8 h_shared_count; 170 __u8 h_reserved2[7]; 171 __le32 h_shared_xattrs[0]; /* shared xattr id array */ 172 }; 173 174 /* Name indexes */ 175 #define EROFS_XATTR_INDEX_USER 1 176 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 177 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 178 #define EROFS_XATTR_INDEX_TRUSTED 4 179 #define EROFS_XATTR_INDEX_LUSTRE 5 180 #define EROFS_XATTR_INDEX_SECURITY 6 181 182 /* xattr entry (for both inline & shared xattrs) */ 183 struct erofs_xattr_entry { 184 __u8 e_name_len; /* length of name */ 185 __u8 e_name_index; /* attribute name index */ 186 __le16 e_value_size; /* size of attribute value */ 187 /* followed by e_name and e_value */ 188 char e_name[0]; /* attribute name */ 189 }; 190 191 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 192 { 193 if (!i_xattr_icount) 194 return 0; 195 196 return sizeof(struct erofs_xattr_ibody_header) + 197 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 198 } 199 200 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 201 202 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 203 { 204 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 205 e->e_name_len + le16_to_cpu(e->e_value_size)); 206 } 207 208 /* maximum supported size of a physical compression cluster */ 209 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) 210 211 /* available compression algorithm types (for h_algorithmtype) */ 212 enum { 213 Z_EROFS_COMPRESSION_LZ4 = 0, 214 Z_EROFS_COMPRESSION_MAX 215 }; 216 #define Z_EROFS_ALL_COMPR_ALGS (1 << (Z_EROFS_COMPRESSION_MAX - 1)) 217 218 /* 14 bytes (+ length field = 16 bytes) */ 219 struct z_erofs_lz4_cfgs { 220 __le16 max_distance; 221 __le16 max_pclusterblks; 222 u8 reserved[10]; 223 } __packed; 224 225 /* 226 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 227 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 228 * (4B) + 2B + (4B) if compacted 2B is on. 229 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) 230 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) 231 */ 232 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 233 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 234 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 235 236 struct z_erofs_map_header { 237 __le32 h_reserved1; 238 __le16 h_advise; 239 /* 240 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 241 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 242 */ 243 __u8 h_algorithmtype; 244 /* 245 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 246 * bit 3-7 : reserved. 247 */ 248 __u8 h_clusterbits; 249 }; 250 251 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 252 253 /* 254 * Fixed-sized output compression ondisk Logical Extent cluster type: 255 * 0 - literal (uncompressed) cluster 256 * 1 - compressed cluster (for the head logical cluster) 257 * 2 - compressed cluster (for the other logical clusters) 258 * 259 * In detail, 260 * 0 - literal (uncompressed) cluster, 261 * di_advise = 0 262 * di_clusterofs = the literal data offset of the cluster 263 * di_blkaddr = the blkaddr of the literal cluster 264 * 265 * 1 - compressed cluster (for the head logical cluster) 266 * di_advise = 1 267 * di_clusterofs = the decompressed data offset of the cluster 268 * di_blkaddr = the blkaddr of the compressed cluster 269 * 270 * 2 - compressed cluster (for the other logical clusters) 271 * di_advise = 2 272 * di_clusterofs = 273 * the decompressed data offset in its own head cluster 274 * di_u.delta[0] = distance to its corresponding head cluster 275 * di_u.delta[1] = distance to its corresponding tail cluster 276 * (di_advise could be 0, 1 or 2) 277 */ 278 enum { 279 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 280 Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1, 281 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 282 Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3, 283 Z_EROFS_VLE_CLUSTER_TYPE_MAX 284 }; 285 286 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 287 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 288 289 /* 290 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the 291 * compressed block count of a compressed extent (in logical clusters, aka. 292 * block count of a pcluster). 293 */ 294 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11) 295 296 struct z_erofs_vle_decompressed_index { 297 __le16 di_advise; 298 /* where to decompress in the head cluster */ 299 __le16 di_clusterofs; 300 301 union { 302 /* for the head cluster */ 303 __le32 blkaddr; 304 /* 305 * for the rest clusters 306 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) 307 * [0] - pointing to the head cluster 308 * [1] - pointing to the tail cluster 309 */ 310 __le16 delta[2]; 311 } di_u; 312 }; 313 314 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 315 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 316 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 317 318 /* dirent sorts in alphabet order, thus we can do binary search */ 319 struct erofs_dirent { 320 __le64 nid; /* node number */ 321 __le16 nameoff; /* start offset of file name */ 322 __u8 file_type; /* file type */ 323 __u8 reserved; /* reserved */ 324 } __packed; 325 326 /* 327 * EROFS file types should match generic FT_* types and 328 * it seems no need to add BUILD_BUG_ONs since potential 329 * unmatchness will break other fses as well... 330 */ 331 332 #define EROFS_NAME_LEN 255 333 334 /* check the EROFS on-disk layout strictly at compile time */ 335 static inline void erofs_check_ondisk_layout_definitions(void) 336 { 337 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 338 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 339 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 340 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 341 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 342 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 343 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 344 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 345 346 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 347 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 348 } 349 350 #endif 351 352