449 lines
14 KiB
C
449 lines
14 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
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/*
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* EROFS (Enhanced ROM File System) on-disk format definition
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*
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* Copyright (C) 2017-2018 HUAWEI, Inc.
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* https://www.huawei.com/
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* Copyright (C) 2021, Alibaba Cloud
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*/
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#ifndef __EROFS_FS_H
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#define __EROFS_FS_H
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#define EROFS_SUPER_OFFSET 1024
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#define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
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#define EROFS_FEATURE_COMPAT_MTIME 0x00000002
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/*
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* Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
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* be incompatible with this kernel version.
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*/
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#define EROFS_FEATURE_INCOMPAT_ZERO_PADDING 0x00000001
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#define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002
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#define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002
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#define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004
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#define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008
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#define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008
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#define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010
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#define EROFS_FEATURE_INCOMPAT_FRAGMENTS 0x00000020
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#define EROFS_FEATURE_INCOMPAT_DEDUPE 0x00000020
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#define EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES 0x00000040
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#define EROFS_ALL_FEATURE_INCOMPAT \
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(EROFS_FEATURE_INCOMPAT_ZERO_PADDING | \
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EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \
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EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \
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EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \
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EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \
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EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 | \
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EROFS_FEATURE_INCOMPAT_ZTAILPACKING | \
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EROFS_FEATURE_INCOMPAT_FRAGMENTS | \
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EROFS_FEATURE_INCOMPAT_DEDUPE | \
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EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES)
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#define EROFS_SB_EXTSLOT_SIZE 16
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struct erofs_deviceslot {
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u8 tag[64]; /* digest(sha256), etc. */
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__le32 blocks; /* total fs blocks of this device */
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__le32 mapped_blkaddr; /* map starting at mapped_blkaddr */
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u8 reserved[56];
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};
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#define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot)
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/* erofs on-disk super block (currently 128 bytes) */
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struct erofs_super_block {
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__le32 magic; /* file system magic number */
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__le32 checksum; /* crc32c(super_block) */
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__le32 feature_compat;
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__u8 blkszbits; /* filesystem block size in bit shift */
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__u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
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__le16 root_nid; /* nid of root directory */
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__le64 inos; /* total valid ino # (== f_files - f_favail) */
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__le64 build_time; /* compact inode time derivation */
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__le32 build_time_nsec; /* compact inode time derivation in ns scale */
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__le32 blocks; /* used for statfs */
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__le32 meta_blkaddr; /* start block address of metadata area */
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__le32 xattr_blkaddr; /* start block address of shared xattr area */
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__u8 uuid[16]; /* 128-bit uuid for volume */
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__u8 volume_name[16]; /* volume name */
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__le32 feature_incompat;
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union {
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/* bitmap for available compression algorithms */
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__le16 available_compr_algs;
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/* customized sliding window size instead of 64k by default */
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__le16 lz4_max_distance;
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} __packed u1;
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__le16 extra_devices; /* # of devices besides the primary device */
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__le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */
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__u8 dirblkbits; /* directory block size in bit shift */
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__u8 xattr_prefix_count; /* # of long xattr name prefixes */
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__le32 xattr_prefix_start; /* start of long xattr prefixes */
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__le64 packed_nid; /* nid of the special packed inode */
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__u8 reserved2[24];
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};
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/*
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* EROFS inode datalayout (i_format in on-disk inode):
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* 0 - uncompressed flat inode without tail-packing inline data:
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* 1 - compressed inode with non-compact indexes:
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* 2 - uncompressed flat inode with tail-packing inline data:
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* 3 - compressed inode with compact indexes:
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* 4 - chunk-based inode with (optional) multi-device support:
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* 5~7 - reserved
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*/
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enum {
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EROFS_INODE_FLAT_PLAIN = 0,
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EROFS_INODE_COMPRESSED_FULL = 1,
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EROFS_INODE_FLAT_INLINE = 2,
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EROFS_INODE_COMPRESSED_COMPACT = 3,
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EROFS_INODE_CHUNK_BASED = 4,
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EROFS_INODE_DATALAYOUT_MAX
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};
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static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
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{
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return datamode == EROFS_INODE_COMPRESSED_COMPACT ||
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datamode == EROFS_INODE_COMPRESSED_FULL;
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}
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/* bit definitions of inode i_format */
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#define EROFS_I_VERSION_MASK 0x01
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#define EROFS_I_DATALAYOUT_MASK 0x07
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#define EROFS_I_VERSION_BIT 0
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#define EROFS_I_DATALAYOUT_BIT 1
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#define EROFS_I_ALL_BIT 4
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#define EROFS_I_ALL ((1 << EROFS_I_ALL_BIT) - 1)
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/* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */
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#define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F
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/* with chunk indexes or just a 4-byte blkaddr array */
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#define EROFS_CHUNK_FORMAT_INDEXES 0x0020
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#define EROFS_CHUNK_FORMAT_ALL \
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(EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES)
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/* 32-byte on-disk inode */
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#define EROFS_INODE_LAYOUT_COMPACT 0
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/* 64-byte on-disk inode */
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#define EROFS_INODE_LAYOUT_EXTENDED 1
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struct erofs_inode_chunk_info {
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__le16 format; /* chunk blkbits, etc. */
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__le16 reserved;
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};
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union erofs_inode_i_u {
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/* total compressed blocks for compressed inodes */
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__le32 compressed_blocks;
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/* block address for uncompressed flat inodes */
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__le32 raw_blkaddr;
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/* for device files, used to indicate old/new device # */
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__le32 rdev;
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/* for chunk-based files, it contains the summary info */
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struct erofs_inode_chunk_info c;
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};
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/* 32-byte reduced form of an ondisk inode */
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struct erofs_inode_compact {
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__le16 i_format; /* inode format hints */
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/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
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__le16 i_xattr_icount;
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__le16 i_mode;
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__le16 i_nlink;
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__le32 i_size;
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__le32 i_reserved;
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union erofs_inode_i_u i_u;
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__le32 i_ino; /* only used for 32-bit stat compatibility */
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__le16 i_uid;
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__le16 i_gid;
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__le32 i_reserved2;
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};
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/* 64-byte complete form of an ondisk inode */
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struct erofs_inode_extended {
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__le16 i_format; /* inode format hints */
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/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
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__le16 i_xattr_icount;
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__le16 i_mode;
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__le16 i_reserved;
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__le64 i_size;
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union erofs_inode_i_u i_u;
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__le32 i_ino; /* only used for 32-bit stat compatibility */
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__le32 i_uid;
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__le32 i_gid;
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__le64 i_mtime;
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__le32 i_mtime_nsec;
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__le32 i_nlink;
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__u8 i_reserved2[16];
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};
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/*
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* inline xattrs (n == i_xattr_icount):
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* erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
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* 12 bytes / \
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* / \
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* /-----------------------\
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* | erofs_xattr_entries+ |
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* +-----------------------+
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* inline xattrs must starts in erofs_xattr_ibody_header,
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* for read-only fs, no need to introduce h_refcount
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*/
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struct erofs_xattr_ibody_header {
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__le32 h_reserved;
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__u8 h_shared_count;
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__u8 h_reserved2[7];
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__le32 h_shared_xattrs[]; /* shared xattr id array */
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};
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/* Name indexes */
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#define EROFS_XATTR_INDEX_USER 1
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#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2
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#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
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#define EROFS_XATTR_INDEX_TRUSTED 4
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#define EROFS_XATTR_INDEX_LUSTRE 5
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#define EROFS_XATTR_INDEX_SECURITY 6
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/*
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* bit 7 of e_name_index is set when it refers to a long xattr name prefix,
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* while the remained lower bits represent the index of the prefix.
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*/
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#define EROFS_XATTR_LONG_PREFIX 0x80
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#define EROFS_XATTR_LONG_PREFIX_MASK 0x7f
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/* xattr entry (for both inline & shared xattrs) */
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struct erofs_xattr_entry {
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__u8 e_name_len; /* length of name */
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__u8 e_name_index; /* attribute name index */
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__le16 e_value_size; /* size of attribute value */
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/* followed by e_name and e_value */
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char e_name[]; /* attribute name */
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};
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/* long xattr name prefix */
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struct erofs_xattr_long_prefix {
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__u8 base_index; /* short xattr name prefix index */
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char infix[]; /* infix apart from short prefix */
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};
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static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
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{
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if (!i_xattr_icount)
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return 0;
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return sizeof(struct erofs_xattr_ibody_header) +
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sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
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}
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#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
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static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
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{
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return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
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e->e_name_len + le16_to_cpu(e->e_value_size));
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}
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/* represent a zeroed chunk (hole) */
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#define EROFS_NULL_ADDR -1
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/* 4-byte block address array */
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#define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32)
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/* 8-byte inode chunk indexes */
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struct erofs_inode_chunk_index {
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__le16 advise; /* always 0, don't care for now */
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__le16 device_id; /* back-end storage id (with bits masked) */
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__le32 blkaddr; /* start block address of this inode chunk */
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};
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/* dirent sorts in alphabet order, thus we can do binary search */
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struct erofs_dirent {
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__le64 nid; /* node number */
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__le16 nameoff; /* start offset of file name */
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__u8 file_type; /* file type */
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__u8 reserved; /* reserved */
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} __packed;
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/*
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* EROFS file types should match generic FT_* types and
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* it seems no need to add BUILD_BUG_ONs since potential
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* unmatchness will break other fses as well...
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*/
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#define EROFS_NAME_LEN 255
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/* maximum supported size of a physical compression cluster */
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#define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024)
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/* available compression algorithm types (for h_algorithmtype) */
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enum {
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Z_EROFS_COMPRESSION_LZ4 = 0,
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Z_EROFS_COMPRESSION_LZMA = 1,
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Z_EROFS_COMPRESSION_MAX
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};
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#define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1)
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/* 14 bytes (+ length field = 16 bytes) */
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struct z_erofs_lz4_cfgs {
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__le16 max_distance;
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__le16 max_pclusterblks;
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u8 reserved[10];
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} __packed;
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/* 14 bytes (+ length field = 16 bytes) */
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struct z_erofs_lzma_cfgs {
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__le32 dict_size;
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__le16 format;
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u8 reserved[8];
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} __packed;
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#define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE)
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/*
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* bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
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* e.g. for 4k logical cluster size, 4B if compacted 2B is off;
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* (4B) + 2B + (4B) if compacted 2B is on.
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* bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
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* bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
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* bit 3 : tailpacking inline pcluster (0 - off; 1 - on)
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* bit 4 : interlaced plain pcluster (0 - off; 1 - on)
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* bit 5 : fragment pcluster (0 - off; 1 - on)
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*/
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#define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
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#define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
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#define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004
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#define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008
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#define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010
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#define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020
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#define Z_EROFS_FRAGMENT_INODE_BIT 7
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struct z_erofs_map_header {
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union {
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/* fragment data offset in the packed inode */
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__le32 h_fragmentoff;
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struct {
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__le16 h_reserved1;
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/* indicates the encoded size of tailpacking data */
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__le16 h_idata_size;
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};
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};
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__le16 h_advise;
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/*
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* bit 0-3 : algorithm type of head 1 (logical cluster type 01);
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* bit 4-7 : algorithm type of head 2 (logical cluster type 11).
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*/
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__u8 h_algorithmtype;
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/*
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* bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
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* bit 3-6 : reserved;
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* bit 7 : move the whole file into packed inode or not.
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*/
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__u8 h_clusterbits;
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};
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/*
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* On-disk logical cluster type:
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* 0 - literal (uncompressed) lcluster
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* 1,3 - compressed lcluster (for HEAD lclusters)
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* 2 - compressed lcluster (for NONHEAD lclusters)
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*
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* In detail,
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* 0 - literal (uncompressed) lcluster,
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* di_advise = 0
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* di_clusterofs = the literal data offset of the lcluster
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* di_blkaddr = the blkaddr of the literal pcluster
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*
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* 1,3 - compressed lcluster (for HEAD lclusters)
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* di_advise = 1 or 3
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* di_clusterofs = the decompressed data offset of the lcluster
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* di_blkaddr = the blkaddr of the compressed pcluster
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*
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* 2 - compressed lcluster (for NONHEAD lclusters)
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* di_advise = 2
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* di_clusterofs =
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* the decompressed data offset in its own HEAD lcluster
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* di_u.delta[0] = distance to this HEAD lcluster
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* di_u.delta[1] = distance to the next HEAD lcluster
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*/
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enum {
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Z_EROFS_LCLUSTER_TYPE_PLAIN = 0,
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Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1,
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Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2,
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Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3,
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Z_EROFS_LCLUSTER_TYPE_MAX
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};
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#define Z_EROFS_LI_LCLUSTER_TYPE_BITS 2
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#define Z_EROFS_LI_LCLUSTER_TYPE_BIT 0
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/* (noncompact only, HEAD) This pcluster refers to partial decompressed data */
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#define Z_EROFS_LI_PARTIAL_REF (1 << 15)
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/*
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* D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
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* compressed block count of a compressed extent (in logical clusters, aka.
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* block count of a pcluster).
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*/
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#define Z_EROFS_LI_D0_CBLKCNT (1 << 11)
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struct z_erofs_lcluster_index {
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__le16 di_advise;
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/* where to decompress in the head lcluster */
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__le16 di_clusterofs;
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union {
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/* for the HEAD lclusters */
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__le32 blkaddr;
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/*
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* for the NONHEAD lclusters
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* [0] - distance to its HEAD lcluster
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* [1] - distance to the next HEAD lcluster
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*/
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__le16 delta[2];
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} di_u;
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};
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#define Z_EROFS_FULL_INDEX_ALIGN(end) \
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(ALIGN(end, 8) + sizeof(struct z_erofs_map_header) + 8)
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/* check the EROFS on-disk layout strictly at compile time */
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static inline void erofs_check_ondisk_layout_definitions(void)
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{
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const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) {
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.h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT
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};
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BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
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BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
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BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
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BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
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BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
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BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4);
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BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8);
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BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
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BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8);
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BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
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/* keep in sync between 2 index structures for better extendibility */
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BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) !=
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sizeof(struct z_erofs_lcluster_index));
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BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
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BUILD_BUG_ON(BIT(Z_EROFS_LI_LCLUSTER_TYPE_BITS) <
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Z_EROFS_LCLUSTER_TYPE_MAX - 1);
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/* exclude old compiler versions like gcc 7.5.0 */
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BUILD_BUG_ON(__builtin_constant_p(fmh) ?
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fmh != cpu_to_le64(1ULL << 63) : 0);
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}
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#endif
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