/* 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/ * Created by Gao Xiang */ #ifndef __EROFS_FS_H #define __EROFS_FS_H #define EROFS_SUPER_OFFSET 1024 #define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001 /* * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should * be incompatible with this kernel version. */ #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001 #define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING /* 128-byte erofs on-disk super block */ struct erofs_super_block { __le32 magic; /* file system magic number */ __le32 checksum; /* crc32c(super_block) */ __le32 feature_compat; __u8 blkszbits; /* support block_size == PAGE_SIZE only */ __u8 reserved; __le16 root_nid; /* nid of root directory */ __le64 inos; /* total valid ino # (== f_files - f_favail) */ __le64 build_time; /* inode v1 time derivation */ __le32 build_time_nsec; /* inode v1 time derivation in nano 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; __u8 reserved2[44]; }; /* * erofs inode datalayout (i_format in on-disk inode): * 0 - inode plain without inline data A: * inode, [xattrs], ... | ... | no-holed data * 1 - inode VLE compression B (legacy): * inode, [xattrs], extents ... | ... * 2 - inode plain with inline data C: * inode, [xattrs], last_inline_data, ... | ... | no-holed data * 3 - inode compression D: * inode, [xattrs], map_header, extents ... | ... * 4~7 - reserved */ enum { EROFS_INODE_FLAT_PLAIN = 0, EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, EROFS_INODE_FLAT_INLINE = 2, EROFS_INODE_FLAT_COMPRESSION = 3, EROFS_INODE_DATALAYOUT_MAX }; static inline bool erofs_inode_is_data_compressed(unsigned int datamode) { return datamode == EROFS_INODE_FLAT_COMPRESSION || datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; } /* bit definitions of inode i_advise */ #define EROFS_I_VERSION_BITS 1 #define EROFS_I_DATALAYOUT_BITS 3 #define EROFS_I_VERSION_BIT 0 #define EROFS_I_DATALAYOUT_BIT 1 /* 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 { /* file total compressed blocks for data mapping 1 */ __le32 compressed_blocks; __le32 raw_blkaddr; /* for device files, used to indicate old/new device # */ __le32 rdev; } i_u; __le32 i_ino; /* only used for 32-bit stat compatibility */ __le16 i_uid; __le16 i_gid; __le32 i_reserved2; }; /* 32 bytes on-disk inode */ #define EROFS_INODE_LAYOUT_COMPACT 0 /* 64 bytes on-disk inode */ #define EROFS_INODE_LAYOUT_EXTENDED 1 /* 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 { /* file total compressed blocks for data mapping 1 */ __le32 compressed_blocks; __le32 raw_blkaddr; /* for device files, used to indicate old/new device # */ __le32 rdev; } i_u; /* only used for 32-bit stat compatibility */ __le32 i_ino; __le32 i_uid; __le32 i_gid; __le64 i_ctime; __le32 i_ctime_nsec; __le32 i_nlink; __u8 i_reserved2[16]; }; #define EROFS_MAX_SHARED_XATTRS (128) /* h_shared_count between 129 ... 255 are special # */ #define EROFS_SHARED_XATTR_EXTENT (255) /* * 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 /* 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 */ }; 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)); } /* available compression algorithm types (for h_algorithmtype) */ enum { Z_EROFS_COMPRESSION_LZ4 = 0, Z_EROFS_COMPRESSION_MAX }; /* * 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. */ #define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0 #define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT) struct z_erofs_map_header { __le32 h_reserved1; __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 3-4 : (physical - logical) cluster bits of head 1: * For example, if logical clustersize = 4096, 1 for 8192. * bit 5-7 : (physical - logical) cluster bits of head 2. */ __u8 h_clusterbits; }; #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 /* * Fixed-sized output compression ondisk Logical Extent cluster type: * 0 - literal (uncompressed) cluster * 1 - compressed cluster (for the head logical cluster) * 2 - compressed cluster (for the other logical clusters) * * In detail, * 0 - literal (uncompressed) cluster, * di_advise = 0 * di_clusterofs = the literal data offset of the cluster * di_blkaddr = the blkaddr of the literal cluster * * 1 - compressed cluster (for the head logical cluster) * di_advise = 1 * di_clusterofs = the decompressed data offset of the cluster * di_blkaddr = the blkaddr of the compressed cluster * * 2 - compressed cluster (for the other logical clusters) * di_advise = 2 * di_clusterofs = * the decompressed data offset in its own head cluster * di_u.delta[0] = distance to its corresponding head cluster * di_u.delta[1] = distance to its corresponding tail cluster * (di_advise could be 0, 1 or 2) */ enum { Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1, Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3, Z_EROFS_VLE_CLUSTER_TYPE_MAX }; #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 struct z_erofs_vle_decompressed_index { __le16 di_advise; /* where to decompress in the head cluster */ __le16 di_clusterofs; union { /* for the head cluster */ __le32 blkaddr; /* * for the rest clusters * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) * [0] - pointing to the head cluster * [1] - pointing to the tail cluster */ __le16 delta[2]; } di_u; }; #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) /* 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; /* * EROFS file types should match generic FT_* types and * it seems no need to add BUILD_BUG_ONs since potential * unmatchness will break other fses as well... */ #define EROFS_NAME_LEN 255 /* check the EROFS on-disk layout strictly at compile time */ static inline void erofs_check_ondisk_layout_definitions(void) { 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 z_erofs_map_header) != 8); BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); } #endif