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Diffstat (limited to 'fs/erofs/erofs_fs.h')
| -rw-r--r-- | fs/erofs/erofs_fs.h | 452 |
1 files changed, 452 insertions, 0 deletions
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h new file mode 100644 index 000000000..dbcd24371 --- /dev/null +++ b/fs/erofs/erofs_fs.h @@ -0,0 +1,452 @@ +/* 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 + +#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_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) + +#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; /* support block_size == PAGE_SIZE only */ + __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 reserved[6]; + __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: + * inode, [xattrs], ... | ... | no-holed data + * 1 - compressed inode with non-compact indexes: + * inode, [xattrs], [map_header], extents ... | ... + * 2 - uncompressed flat inode with tail-packing inline data: + * inode, [xattrs], tailpacking data, ... | ... | no-holed data + * 3 - compressed inode with compact indexes: + * inode, [xattrs], map_header, extents ... | ... + * 4 - chunk-based inode with (optional) multi-device support: + * inode, [xattrs], chunk indexes ... | ... + * 5~7 - 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_CHUNK_BASED = 4, + 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_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) + +struct erofs_inode_chunk_info { + __le16 format; /* chunk blkbits, etc. */ + __le16 reserved; +}; + +/* 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 { + /* 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; + } i_u; + __le32 i_ino; /* only used for 32-bit stat compatibility */ + __le16 i_uid; + __le16 i_gid; + __le32 i_reserved2; +}; + +/* 32-byte on-disk inode */ +#define EROFS_INODE_LAYOUT_COMPACT 0 +/* 64-byte 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 { + /* 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; + } i_u; + + /* only used for 32-bit stat compatibility */ + __le32 i_ino; + + __le32 i_uid; + __le32 i_gid; + __le64 i_mtime; + __le32 i_mtime_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[]; /* 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[]; /* 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)); +} + +/* 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 */ +}; + +/* 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_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; +}; + +#define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 + +/* + * Fixed-sized output compression 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_VLE_CLUSTER_TYPE_PLAIN = 0, + Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 = 1, + Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, + Z_EROFS_VLE_CLUSTER_TYPE_HEAD2 = 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 + +/* (noncompact only, HEAD) This pcluster refers to partial decompressed data */ +#define Z_EROFS_VLE_DI_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_VLE_DI_D0_CBLKCNT (1 << 11) + +struct z_erofs_vle_decompressed_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_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) +{ + const __le64 fmh = *(__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_vle_decompressed_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_vle_decompressed_index)); + BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128); + + BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < + Z_EROFS_VLE_CLUSTER_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 |