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 */ 24struct 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 */ 57enum { 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 65static 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#define EROFS_I_ALL \ 79 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1) 80 81/* 32-byte reduced form of an ondisk inode */ 82struct erofs_inode_compact { 83 __le16 i_format; /* inode format hints */ 84 85/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 86 __le16 i_xattr_icount; 87 __le16 i_mode; 88 __le16 i_nlink; 89 __le32 i_size; 90 __le32 i_reserved; 91 union { 92 /* file total compressed blocks for data mapping 1 */ 93 __le32 compressed_blocks; 94 __le32 raw_blkaddr; 95 96 /* for device files, used to indicate old/new device # */ 97 __le32 rdev; 98 } i_u; 99 __le32 i_ino; /* only used for 32-bit stat compatibility */ 100 __le16 i_uid; 101 __le16 i_gid; 102 __le32 i_reserved2; 103}; 104 105/* 32 bytes on-disk inode */ 106#define EROFS_INODE_LAYOUT_COMPACT 0 107/* 64 bytes on-disk inode */ 108#define EROFS_INODE_LAYOUT_EXTENDED 1 109 110/* 64-byte complete form of an ondisk inode */ 111struct erofs_inode_extended { 112 __le16 i_format; /* inode format hints */ 113 114/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ 115 __le16 i_xattr_icount; 116 __le16 i_mode; 117 __le16 i_reserved; 118 __le64 i_size; 119 union { 120 /* file total compressed blocks for data mapping 1 */ 121 __le32 compressed_blocks; 122 __le32 raw_blkaddr; 123 124 /* for device files, used to indicate old/new device # */ 125 __le32 rdev; 126 } i_u; 127 128 /* only used for 32-bit stat compatibility */ 129 __le32 i_ino; 130 131 __le32 i_uid; 132 __le32 i_gid; 133 __le64 i_ctime; 134 __le32 i_ctime_nsec; 135 __le32 i_nlink; 136 __u8 i_reserved2[16]; 137}; 138 139#define EROFS_MAX_SHARED_XATTRS (128) 140/* h_shared_count between 129 ... 255 are special # */ 141#define EROFS_SHARED_XATTR_EXTENT (255) 142 143/* 144 * inline xattrs (n == i_xattr_icount): 145 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes 146 * 12 bytes / \ 147 * / \ 148 * /-----------------------\ 149 * | erofs_xattr_entries+ | 150 * +-----------------------+ 151 * inline xattrs must starts in erofs_xattr_ibody_header, 152 * for read-only fs, no need to introduce h_refcount 153 */ 154struct erofs_xattr_ibody_header { 155 __le32 h_reserved; 156 __u8 h_shared_count; 157 __u8 h_reserved2[7]; 158 __le32 h_shared_xattrs[0]; /* shared xattr id array */ 159}; 160 161/* Name indexes */ 162#define EROFS_XATTR_INDEX_USER 1 163#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 164#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 165#define EROFS_XATTR_INDEX_TRUSTED 4 166#define EROFS_XATTR_INDEX_LUSTRE 5 167#define EROFS_XATTR_INDEX_SECURITY 6 168 169/* xattr entry (for both inline & shared xattrs) */ 170struct erofs_xattr_entry { 171 __u8 e_name_len; /* length of name */ 172 __u8 e_name_index; /* attribute name index */ 173 __le16 e_value_size; /* size of attribute value */ 174 /* followed by e_name and e_value */ 175 char e_name[0]; /* attribute name */ 176}; 177 178static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) 179{ 180 if (!i_xattr_icount) 181 return 0; 182 183 return sizeof(struct erofs_xattr_ibody_header) + 184 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); 185} 186 187#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) 188 189static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) 190{ 191 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + 192 e->e_name_len + le16_to_cpu(e->e_value_size)); 193} 194 195/* available compression algorithm types (for h_algorithmtype) */ 196enum { 197 Z_EROFS_COMPRESSION_LZ4 = 0, 198 Z_EROFS_COMPRESSION_MAX 199}; 200 201/* 202 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) 203 * e.g. for 4k logical cluster size, 4B if compacted 2B is off; 204 * (4B) + 2B + (4B) if compacted 2B is on. 205 */ 206#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0 207 208#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT) 209 210struct z_erofs_map_header { 211 __le32 h_reserved1; 212 __le16 h_advise; 213 /* 214 * bit 0-3 : algorithm type of head 1 (logical cluster type 01); 215 * bit 4-7 : algorithm type of head 2 (logical cluster type 11). 216 */ 217 __u8 h_algorithmtype; 218 /* 219 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; 220 * bit 3-4 : (physical - logical) cluster bits of head 1: 221 * For example, if logical clustersize = 4096, 1 for 8192. 222 * bit 5-7 : (physical - logical) cluster bits of head 2. 223 */ 224 __u8 h_clusterbits; 225}; 226 227#define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 228 229/* 230 * Fixed-sized output compression ondisk Logical Extent cluster type: 231 * 0 - literal (uncompressed) cluster 232 * 1 - compressed cluster (for the head logical cluster) 233 * 2 - compressed cluster (for the other logical clusters) 234 * 235 * In detail, 236 * 0 - literal (uncompressed) cluster, 237 * di_advise = 0 238 * di_clusterofs = the literal data offset of the cluster 239 * di_blkaddr = the blkaddr of the literal cluster 240 * 241 * 1 - compressed cluster (for the head logical cluster) 242 * di_advise = 1 243 * di_clusterofs = the decompressed data offset of the cluster 244 * di_blkaddr = the blkaddr of the compressed cluster 245 * 246 * 2 - compressed cluster (for the other logical clusters) 247 * di_advise = 2 248 * di_clusterofs = 249 * the decompressed data offset in its own head cluster 250 * di_u.delta[0] = distance to its corresponding head cluster 251 * di_u.delta[1] = distance to its corresponding tail cluster 252 * (di_advise could be 0, 1 or 2) 253 */ 254enum { 255 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, 256 Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1, 257 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, 258 Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3, 259 Z_EROFS_VLE_CLUSTER_TYPE_MAX 260}; 261 262#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 263#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 264 265struct z_erofs_vle_decompressed_index { 266 __le16 di_advise; 267 /* where to decompress in the head cluster */ 268 __le16 di_clusterofs; 269 270 union { 271 /* for the head cluster */ 272 __le32 blkaddr; 273 /* 274 * for the rest clusters 275 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) 276 * [0] - pointing to the head cluster 277 * [1] - pointing to the tail cluster 278 */ 279 __le16 delta[2]; 280 } di_u; 281}; 282 283#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ 284 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ 285 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) 286 287/* dirent sorts in alphabet order, thus we can do binary search */ 288struct erofs_dirent { 289 __le64 nid; /* node number */ 290 __le16 nameoff; /* start offset of file name */ 291 __u8 file_type; /* file type */ 292 __u8 reserved; /* reserved */ 293} __packed; 294 295/* 296 * EROFS file types should match generic FT_* types and 297 * it seems no need to add BUILD_BUG_ONs since potential 298 * unmatchness will break other fses as well... 299 */ 300 301#define EROFS_NAME_LEN 255 302 303/* check the EROFS on-disk layout strictly at compile time */ 304static inline void erofs_check_ondisk_layout_definitions(void) 305{ 306 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); 307 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); 308 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); 309 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); 310 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); 311 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); 312 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); 313 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); 314 315 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < 316 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); 317} 318 319#endif 320 321