/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */ /* * EROFS (Enhanced ROM File System) on-disk format definition * * Copyright (C) 2017-2018 HUAWEI, Inc. * https://www.huawei.com/ * Copyright (C) 2021, Alibaba Cloud */ #ifndef __EROFS_FS_H #define __EROFS_FS_H #include #include #include #include #include #define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2 #define EROFS_SUPER_OFFSET 1024 #define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001 #define EROFS_FEATURE_COMPAT_MTIME 0x00000002 /* * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should * be incompatible with this kernel version. */ #define EROFS_FEATURE_INCOMPAT_ZERO_PADDING 0x00000001 #define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002 #define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002 #define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004 #define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008 #define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008 #define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010 #define EROFS_FEATURE_INCOMPAT_FRAGMENTS 0x00000020 #define EROFS_FEATURE_INCOMPAT_DEDUPE 0x00000020 #define EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES 0x00000040 #define EROFS_ALL_FEATURE_INCOMPAT \ (EROFS_FEATURE_INCOMPAT_ZERO_PADDING | \ EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \ EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \ EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \ EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \ EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 | \ EROFS_FEATURE_INCOMPAT_ZTAILPACKING | \ EROFS_FEATURE_INCOMPAT_FRAGMENTS | \ EROFS_FEATURE_INCOMPAT_DEDUPE | \ EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES) #define EROFS_SB_EXTSLOT_SIZE 16 struct erofs_deviceslot { u8 tag[64]; /* digest(sha256), etc. */ __le32 blocks; /* total fs blocks of this device */ __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */ u8 reserved[56]; }; #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot) /* erofs on-disk super block (currently 128 bytes) */ struct erofs_super_block { __le32 magic; /* file system magic number */ __le32 checksum; /* crc32c(super_block) */ __le32 feature_compat; __u8 blkszbits; /* filesystem block size in bit shift */ __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */ __le16 root_nid; /* nid of root directory */ __le64 inos; /* total valid ino # (== f_files - f_favail) */ __le64 build_time; /* compact inode time derivation */ __le32 build_time_nsec; /* compact inode time derivation in ns scale */ __le32 blocks; /* used for statfs */ __le32 meta_blkaddr; /* start block address of metadata area */ __le32 xattr_blkaddr; /* start block address of shared xattr area */ __u8 uuid[16]; /* 128-bit uuid for volume */ __u8 volume_name[16]; /* volume name */ __le32 feature_incompat; union { /* bitmap for available compression algorithms */ __le16 available_compr_algs; /* customized sliding window size instead of 64k by default */ __le16 lz4_max_distance; } __packed u1; __le16 extra_devices; /* # of devices besides the primary device */ __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */ __u8 dirblkbits; /* directory block size in bit shift */ __u8 xattr_prefix_count; /* # of long xattr name prefixes */ __le32 xattr_prefix_start; /* start of long xattr prefixes */ __le64 packed_nid; /* nid of the special packed inode */ __u8 reserved2[24]; }; /* * EROFS inode datalayout (i_format in on-disk inode): * 0 - uncompressed flat inode without tail-packing inline data: * 1 - compressed inode with non-compact indexes: * 2 - uncompressed flat inode with tail-packing inline data: * 3 - compressed inode with compact indexes: * 4 - chunk-based inode with (optional) multi-device support: * 5~7 - reserved */ enum { EROFS_INODE_FLAT_PLAIN = 0, EROFS_INODE_COMPRESSED_FULL = 1, EROFS_INODE_FLAT_INLINE = 2, EROFS_INODE_COMPRESSED_COMPACT = 3, EROFS_INODE_CHUNK_BASED = 4, EROFS_INODE_DATALAYOUT_MAX }; static inline bool erofs_inode_is_data_compressed(unsigned int datamode) { return datamode == EROFS_INODE_COMPRESSED_COMPACT || datamode == EROFS_INODE_COMPRESSED_FULL; } /* bit definitions of inode i_format */ #define EROFS_I_VERSION_BITS 1 #define EROFS_I_DATALAYOUT_BITS 3 #define EROFS_I_VERSION_BIT 0 #define EROFS_I_DATALAYOUT_BIT 1 #define EROFS_I_ALL \ ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1) /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */ #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F /* with chunk indexes or just a 4-byte blkaddr array */ #define EROFS_CHUNK_FORMAT_INDEXES 0x0020 #define EROFS_CHUNK_FORMAT_ALL \ (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES) /* 32-byte on-disk inode */ #define EROFS_INODE_LAYOUT_COMPACT 0 /* 64-byte on-disk inode */ #define EROFS_INODE_LAYOUT_EXTENDED 1 struct erofs_inode_chunk_info { __le16 format; /* chunk blkbits, etc. */ __le16 reserved; }; union erofs_inode_i_u { /* total compressed blocks for compressed inodes */ __le32 compressed_blocks; /* block address for uncompressed flat inodes */ __le32 raw_blkaddr; /* for device files, used to indicate old/new device # */ __le32 rdev; /* for chunk-based files, it contains the summary info */ struct erofs_inode_chunk_info c; }; /* 32-byte reduced form of an ondisk inode */ struct erofs_inode_compact { __le16 i_format; /* inode format hints */ /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ __le16 i_xattr_icount; __le16 i_mode; __le16 i_nlink; __le32 i_size; __le32 i_reserved; union erofs_inode_i_u i_u; __le32 i_ino; /* only used for 32-bit stat compatibility */ __le16 i_uid; __le16 i_gid; __le32 i_reserved2; }; /* 64-byte complete form of an ondisk inode */ struct erofs_inode_extended { __le16 i_format; /* inode format hints */ /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ __le16 i_xattr_icount; __le16 i_mode; __le16 i_reserved; __le64 i_size; union erofs_inode_i_u i_u; __le32 i_ino; /* only used for 32-bit stat compatibility */ __le32 i_uid; __le32 i_gid; __le64 i_mtime; __le32 i_mtime_nsec; __le32 i_nlink; __u8 i_reserved2[16]; }; /* * inline xattrs (n == i_xattr_icount): * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes * 12 bytes / \ * / \ * /-----------------------\ * | erofs_xattr_entries+ | * +-----------------------+ * inline xattrs must starts in erofs_xattr_ibody_header, * for read-only fs, no need to introduce h_refcount */ struct erofs_xattr_ibody_header { __le32 h_reserved; __u8 h_shared_count; __u8 h_reserved2[7]; __le32 h_shared_xattrs[0]; /* shared xattr id array */ }; /* Name indexes */ #define EROFS_XATTR_INDEX_USER 1 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 #define EROFS_XATTR_INDEX_TRUSTED 4 #define EROFS_XATTR_INDEX_LUSTRE 5 #define EROFS_XATTR_INDEX_SECURITY 6 /* * bit 7 of e_name_index is set when it refers to a long xattr name prefix, * while the remained lower bits represent the index of the prefix. */ #define EROFS_XATTR_LONG_PREFIX 0x80 #define EROFS_XATTR_LONG_PREFIX_MASK 0x7f /* xattr entry (for both inline & shared xattrs) */ struct erofs_xattr_entry { __u8 e_name_len; /* length of name */ __u8 e_name_index; /* attribute name index */ __le16 e_value_size; /* size of attribute value */ /* followed by e_name and e_value */ char e_name[0]; /* attribute name */ }; /* long xattr name prefix */ struct erofs_xattr_long_prefix { __u8 base_index; /* short xattr name prefix index */ char infix[0]; /* infix apart from short prefix */ }; static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) { if (!i_xattr_icount) return 0; return sizeof(struct erofs_xattr_ibody_header) + sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); } #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) { return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + e->e_name_len + le16_to_cpu(e->e_value_size)); } /* represent a zeroed chunk (hole) */ #define EROFS_NULL_ADDR -1 /* 4-byte block address array */ #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32) /* 8-byte inode chunk indexes */ struct erofs_inode_chunk_index { __le16 advise; /* always 0, don't care for now */ __le16 device_id; /* back-end storage id (with bits masked) */ __le32 blkaddr; /* start block address of this inode chunk */ }; /* dirent sorts in alphabet order, thus we can do binary search */ struct erofs_dirent { __le64 nid; /* node number */ __le16 nameoff; /* start offset of file name */ __u8 file_type; /* file type */ __u8 reserved; /* reserved */ } __packed; /* file types used in inode_info->flags */ enum { EROFS_FT_UNKNOWN, EROFS_FT_REG_FILE, EROFS_FT_DIR, EROFS_FT_CHRDEV, EROFS_FT_BLKDEV, EROFS_FT_FIFO, EROFS_FT_SOCK, EROFS_FT_SYMLINK, EROFS_FT_MAX }; #define EROFS_NAME_LEN 255 /* maximum supported size of a physical compression cluster */ #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024) /* available compression algorithm types (for h_algorithmtype) */ enum { Z_EROFS_COMPRESSION_LZ4 = 0, Z_EROFS_COMPRESSION_LZMA = 1, Z_EROFS_COMPRESSION_DEFLATE = 2, Z_EROFS_COMPRESSION_MAX }; #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1) /* 14 bytes (+ length field = 16 bytes) */ struct z_erofs_lz4_cfgs { __le16 max_distance; __le16 max_pclusterblks; u8 reserved[10]; } __packed; /* 14 bytes (+ length field = 16 bytes) */ struct z_erofs_lzma_cfgs { __le32 dict_size; __le16 format; u8 reserved[8]; } __packed; #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE) /* * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) * e.g. for 4k logical cluster size, 4B if compacted 2B is off; * (4B) + 2B + (4B) if compacted 2B is on. * bit 1 : HEAD1 big pcluster (0 - off; 1 - on) * bit 2 : HEAD2 big pcluster (0 - off; 1 - on) * bit 3 : tailpacking inline pcluster (0 - off; 1 - on) * bit 4 : interlaced plain pcluster (0 - off; 1 - on) * bit 5 : fragment pcluster (0 - off; 1 - on) */ #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004 #define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008 #define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010 #define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020 #define Z_EROFS_FRAGMENT_INODE_BIT 7 struct z_erofs_map_header { union { /* fragment data offset in the packed inode */ __le32 h_fragmentoff; struct { __le16 h_reserved1; /* indicates the encoded size of tailpacking data */ __le16 h_idata_size; }; }; __le16 h_advise; /* * bit 0-3 : algorithm type of head 1 (logical cluster type 01); * bit 4-7 : algorithm type of head 2 (logical cluster type 11). */ __u8 h_algorithmtype; /* * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; * bit 3-6 : reserved; * bit 7 : move the whole file into packed inode or not. */ __u8 h_clusterbits; }; /* * On-disk logical cluster type: * 0 - literal (uncompressed) lcluster * 1,3 - compressed lcluster (for HEAD lclusters) * 2 - compressed lcluster (for NONHEAD lclusters) * * In detail, * 0 - literal (uncompressed) lcluster, * di_advise = 0 * di_clusterofs = the literal data offset of the lcluster * di_blkaddr = the blkaddr of the literal pcluster * * 1,3 - compressed lcluster (for HEAD lclusters) * di_advise = 1 or 3 * di_clusterofs = the decompressed data offset of the lcluster * di_blkaddr = the blkaddr of the compressed pcluster * * 2 - compressed lcluster (for NONHEAD lclusters) * di_advise = 2 * di_clusterofs = * the decompressed data offset in its own HEAD lcluster * di_u.delta[0] = distance to this HEAD lcluster * di_u.delta[1] = distance to the next HEAD lcluster */ enum { Z_EROFS_LCLUSTER_TYPE_PLAIN = 0, Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1, Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2, Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3, Z_EROFS_LCLUSTER_TYPE_MAX }; #define Z_EROFS_LI_LCLUSTER_TYPE_BITS 2 #define Z_EROFS_LI_LCLUSTER_TYPE_BIT 0 /* (noncompact only, HEAD) This pcluster refers to partial decompressed data */ #define Z_EROFS_LI_PARTIAL_REF (1 << 15) /* * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the * compressed block count of a compressed extent (in logical clusters, aka. * block count of a pcluster). */ #define Z_EROFS_LI_D0_CBLKCNT (1 << 11) struct z_erofs_lcluster_index { __le16 di_advise; /* where to decompress in the head lcluster */ __le16 di_clusterofs; union { /* for the HEAD lclusters */ __le32 blkaddr; /* * for the NONHEAD lclusters * [0] - distance to its HEAD lcluster * [1] - distance to the next HEAD lcluster */ __le16 delta[2]; } di_u; }; #define Z_EROFS_FULL_INDEX_ALIGN(end) \ (round_up(end, 8) + sizeof(struct z_erofs_map_header) + 8) /* check the EROFS on-disk layout strictly at compile time */ static inline void erofs_check_ondisk_layout_definitions(void) { const __le64 fmh __maybe_unused = *(__le64 *)&(struct z_erofs_map_header) { .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT }; BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4); BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8); BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8); BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); /* keep in sync between 2 index structures for better extendibility */ BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != sizeof(struct z_erofs_lcluster_index)); BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); BUILD_BUG_ON(BIT(Z_EROFS_LI_LCLUSTER_TYPE_BITS) < Z_EROFS_LCLUSTER_TYPE_MAX - 1); /* exclude old compiler versions like gcc 7.5.0 */ BUILD_BUG_ON(__builtin_constant_p(fmh) ? fmh != cpu_to_le64(1ULL << 63) : 0); } #endif