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_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 22 23 /* 128-byte erofs on-disk super block */ 24 struct erofs_super_block { 25 __le32 magic; /* file system magic number */ 26 __le32 checksum; /* crc32c(super_block) */ 27 __le32 feature_compat; 28 __u8 blkszbits; /* support block_size == PAGE_SIZE only */ 29 __u8 reserved; 30 31 __le16 root_nid; /* nid of root directory */ 32 __le64 inos; /* total valid ino # (== f_files - f_favail) */ 33 34 __le64 build_time; /* inode v1 time derivation */ 35 __le32 build_time_nsec; /* inode v1 time derivation in nano scale */ 36 __le32 blocks; /* used for statfs */ 37 __le32 meta_blkaddr; /* start block address of metadata area */ 38 __le32 xattr_blkaddr; /* start block address of shared xattr area */ 39 __u8 uuid[16]; /* 128-bit uuid for volume */ 40 __u8 volume_name[16]; /* volume name */ 41 __le32 feature_incompat; 42 __u8 reserved2[44]; 43 }; 44 45 /* 46 * erofs inode datalayout (i_format in on-disk inode): 47 * 0 - inode plain without inline data A: 48 * inode, [xattrs], ... | ... | no-holed data 49 * 1 - inode VLE compression B (legacy): 50 * inode, [xattrs], extents ... | ... 51 * 2 - inode plain with inline data C: 52 * inode, [xattrs], last_inline_data, ... | ... | no-holed data 53 * 3 - inode compression D: 54 * inode, [xattrs], map_header, extents ... | ... 55 * 4~7 - reserved 56 */ 57 enum { 58 EROFS_INODE_FLAT_PLAIN = 0, 59 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, 60 EROFS_INODE_FLAT_INLINE = 2, 61 EROFS_INODE_FLAT_COMPRESSION = 3, 62 EROFS_INODE_DATALAYOUT_MAX 63 }; 64 65 static inline bool erofs_inode_is_data_compressed(unsigned int datamode) 66 { 67 return datamode == EROFS_INODE_FLAT_COMPRESSION || 68 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; 69 } 70 71 /* bit definitions of inode i_advise */ 72 #define EROFS_I_VERSION_BITS 1 73 #define EROFS_I_DATALAYOUT_BITS 3 74 75 #define EROFS_I_VERSION_BIT 0 76 #define EROFS_I_DATALAYOUT_BIT 1 77 78 /* 32-byte reduced form of an ondisk inode */ 79 struct erofs_inode_compact { 80 __le16 i_format; /* inode format hints */ 81 82 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 83 __le16 i_xattr_icount; 84 __le16 i_mode; 85 __le16 i_nlink; 86 __le32 i_size; 87 __le32 i_reserved; 88 union { 89 /* file total compressed blocks for data mapping 1 */ 90 __le32 compressed_blocks; 91 __le32 raw_blkaddr; 92 93 /* for device files, used to indicate old/new device # */ 94 __le32 rdev; 95 } i_u; 96 __le32 i_ino; /* only used for 32-bit stat compatibility */ 97 __le16 i_uid; 98 __le16 i_gid; 99 __le32 i_reserved2; 100 }; 101 102 /* 32 bytes on-disk inode */ 103 #define EROFS_INODE_LAYOUT_COMPACT 0 104 /* 64 bytes on-disk inode */ 105 #define EROFS_INODE_LAYOUT_EXTENDED 1 106 107 /* 64-byte complete form of an ondisk inode */ 108 struct erofs_inode_extended { 109 __le16 i_format; /* inode format hints */ 110 111 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 112 __le16 i_xattr_icount; 113 __le16 i_mode; 114 __le16 i_reserved; 115 __le64 i_size; 116 union { 117 /* file total compressed blocks for data mapping 1 */ 118 __le32 compressed_blocks; 119 __le32 raw_blkaddr; 120 121 /* for device files, used to indicate old/new device # */ 122 __le32 rdev; 123 } i_u; 124 125 /* only used for 32-bit stat compatibility */ 126 __le32 i_ino; 127 128 __le32 i_uid; 129 __le32 i_gid; 130 __le64 i_ctime; 131 __le32 i_ctime_nsec; 132 __le32 i_nlink; 133 __u8 i_reserved2[16]; 134 }; 135 136 #define EROFS_MAX_SHARED_XATTRS (128) 137 /* h_shared_count between 129 ... 255 are special # */ 138 #define EROFS_SHARED_XATTR_EXTENT (255) 139 140 /* 141 * inline xattrs (n == i_xattr_icount): 142 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 143 * 12 bytes / \ 144 * / \ 145 * /-----------------------\ 146 * | erofs_xattr_entries+ | 147 * +-----------------------+ 148 * inline xattrs must starts in erofs_xattr_ibody_header, 149 * for read-only fs, no need to introduce h_refcount 150 */ 151 struct erofs_xattr_ibody_header { 152 __le32 h_reserved; 153 __u8 h_shared_count; 154 __u8 h_reserved2[7]; 155 __le32 h_shared_xattrs[0]; /* shared xattr id array */ 156 }; 157 158 /* Name indexes */ 159 #define EROFS_XATTR_INDEX_USER 1 160 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 161 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 162 #define EROFS_XATTR_INDEX_TRUSTED 4 163 #define EROFS_XATTR_INDEX_LUSTRE 5 164 #define EROFS_XATTR_INDEX_SECURITY 6 165 166 /* xattr entry (for both inline & shared xattrs) */ 167 struct erofs_xattr_entry { 168 __u8 e_name_len; /* length of name */ 169 __u8 e_name_index; /* attribute name index */ 170 __le16 e_value_size; /* size of attribute value */ 171 /* followed by e_name and e_value */ 172 char e_name[0]; /* attribute name */ 173 }; 174 175 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 176 { 177 if (!i_xattr_icount) 178 return 0; 179 180 return sizeof(struct erofs_xattr_ibody_header) + 181 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 182 } 183 184 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 185 186 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 187 { 188 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 189 e->e_name_len + le16_to_cpu(e->e_value_size)); 190 } 191 192 /* available compression algorithm types (for h_algorithmtype) */ 193 enum { 194 Z_EROFS_COMPRESSION_LZ4 = 0, 195 Z_EROFS_COMPRESSION_MAX 196 }; 197 198 /* 199 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 200 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 201 * (4B) + 2B + (4B) if compacted 2B is on. 202 */ 203 #define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0 204 205 #define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT) 206 207 struct z_erofs_map_header { 208 __le32 h_reserved1; 209 __le16 h_advise; 210 /* 211 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 212 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 213 */ 214 __u8 h_algorithmtype; 215 /* 216 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 217 * bit 3-4 : (physical - logical) cluster bits of head 1: 218 * For example, if logical clustersize = 4096, 1 for 8192. 219 * bit 5-7 : (physical - logical) cluster bits of head 2. 220 */ 221 __u8 h_clusterbits; 222 }; 223 224 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 225 226 /* 227 * Fixed-sized output compression ondisk Logical Extent cluster type: 228 * 0 - literal (uncompressed) cluster 229 * 1 - compressed cluster (for the head logical cluster) 230 * 2 - compressed cluster (for the other logical clusters) 231 * 232 * In detail, 233 * 0 - literal (uncompressed) cluster, 234 * di_advise = 0 235 * di_clusterofs = the literal data offset of the cluster 236 * di_blkaddr = the blkaddr of the literal cluster 237 * 238 * 1 - compressed cluster (for the head logical cluster) 239 * di_advise = 1 240 * di_clusterofs = the decompressed data offset of the cluster 241 * di_blkaddr = the blkaddr of the compressed cluster 242 * 243 * 2 - compressed cluster (for the other logical clusters) 244 * di_advise = 2 245 * di_clusterofs = 246 * the decompressed data offset in its own head cluster 247 * di_u.delta[0] = distance to its corresponding head cluster 248 * di_u.delta[1] = distance to its corresponding tail cluster 249 * (di_advise could be 0, 1 or 2) 250 */ 251 enum { 252 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 253 Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1, 254 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 255 Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3, 256 Z_EROFS_VLE_CLUSTER_TYPE_MAX 257 }; 258 259 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 260 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 261 262 struct z_erofs_vle_decompressed_index { 263 __le16 di_advise; 264 /* where to decompress in the head cluster */ 265 __le16 di_clusterofs; 266 267 union { 268 /* for the head cluster */ 269 __le32 blkaddr; 270 /* 271 * for the rest clusters 272 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) 273 * [0] - pointing to the head cluster 274 * [1] - pointing to the tail cluster 275 */ 276 __le16 delta[2]; 277 } di_u; 278 }; 279 280 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 281 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 282 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 283 284 /* dirent sorts in alphabet order, thus we can do binary search */ 285 struct erofs_dirent { 286 __le64 nid; /* node number */ 287 __le16 nameoff; /* start offset of file name */ 288 __u8 file_type; /* file type */ 289 __u8 reserved; /* reserved */ 290 } __packed; 291 292 /* 293 * EROFS file types should match generic FT_* types and 294 * it seems no need to add BUILD_BUG_ONs since potential 295 * unmatchness will break other fses as well... 296 */ 297 298 #define EROFS_NAME_LEN 255 299 300 /* check the EROFS on-disk layout strictly at compile time */ 301 static inline void erofs_check_ondisk_layout_definitions(void) 302 { 303 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 304 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 305 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 306 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 307 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 308 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 309 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 310 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 311 312 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 313 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 314 } 315 316 #endif 317 318