324 lines
9.6 KiB
C
324 lines
9.6 KiB
C
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/* 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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* http://www.huawei.com/
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* Created by Gao Xiang <gaoxiang25@huawei.com>
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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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/*
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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_LZ4_0PADDING 0x00000001
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#define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING
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/* 128-byte erofs on-disk super block */
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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; /* support block_size == PAGE_SIZE only */
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__u8 reserved;
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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; /* inode v1 time derivation */
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__le32 build_time_nsec; /* inode v1 time derivation in nano 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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__u8 reserved2[44];
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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 - inode plain without inline data A:
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* inode, [xattrs], ... | ... | no-holed data
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* 1 - inode VLE compression B (legacy):
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* inode, [xattrs], extents ... | ...
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* 2 - inode plain with inline data C:
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* inode, [xattrs], last_inline_data, ... | ... | no-holed data
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* 3 - inode compression D:
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* inode, [xattrs], map_header, extents ... | ...
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* 4~7 - 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_FLAT_COMPRESSION_LEGACY = 1,
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EROFS_INODE_FLAT_INLINE = 2,
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EROFS_INODE_FLAT_COMPRESSION = 3,
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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_FLAT_COMPRESSION ||
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datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
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}
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/* bit definitions of inode i_advise */
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#define EROFS_I_VERSION_BITS 1
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#define EROFS_I_DATALAYOUT_BITS 3
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#define EROFS_I_VERSION_BIT 0
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#define EROFS_I_DATALAYOUT_BIT 1
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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 {
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/* file total compressed blocks for data mapping 1 */
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__le32 compressed_blocks;
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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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} 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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/* 32 bytes on-disk inode */
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#define EROFS_INODE_LAYOUT_COMPACT 0
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/* 64 bytes on-disk inode */
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#define EROFS_INODE_LAYOUT_EXTENDED 1
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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 {
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/* file total compressed blocks for data mapping 1 */
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__le32 compressed_blocks;
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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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} i_u;
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/* only used for 32-bit stat compatibility */
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__le32 i_ino;
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__le32 i_uid;
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__le32 i_gid;
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__le64 i_ctime;
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__le32 i_ctime_nsec;
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__le32 i_nlink;
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__u8 i_reserved2[16];
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};
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#define EROFS_MAX_SHARED_XATTRS (128)
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/* h_shared_count between 129 ... 255 are special # */
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#define EROFS_SHARED_XATTR_EXTENT (255)
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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[0]; /* 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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/* 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[0]; /* attribute name */
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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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/* 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_MAX
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};
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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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*/
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#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0
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#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
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struct z_erofs_map_header {
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__le32 h_reserved1;
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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 3-4 : (physical - logical) cluster bits of head 1:
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* For example, if logical clustersize = 4096, 1 for 8192.
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* bit 5-7 : (physical - logical) cluster bits of head 2.
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*/
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__u8 h_clusterbits;
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};
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#define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8
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/*
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* Fixed-sized output compression ondisk Logical Extent cluster type:
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* 0 - literal (uncompressed) cluster
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* 1 - compressed cluster (for the head logical cluster)
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* 2 - compressed cluster (for the other logical clusters)
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*
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* In detail,
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* 0 - literal (uncompressed) cluster,
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* di_advise = 0
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* di_clusterofs = the literal data offset of the cluster
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* di_blkaddr = the blkaddr of the literal cluster
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*
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* 1 - compressed cluster (for the head logical cluster)
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* di_advise = 1
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* di_clusterofs = the decompressed data offset of the cluster
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* di_blkaddr = the blkaddr of the compressed cluster
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*
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* 2 - compressed cluster (for the other logical clusters)
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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 cluster
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* di_u.delta[0] = distance to its corresponding head cluster
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* di_u.delta[1] = distance to its corresponding tail cluster
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* (di_advise could be 0, 1 or 2)
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*/
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enum {
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Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0,
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Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1,
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Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2,
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Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3,
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Z_EROFS_VLE_CLUSTER_TYPE_MAX
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};
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#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2
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#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0
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struct z_erofs_vle_decompressed_index {
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__le16 di_advise;
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/* where to decompress in the head cluster */
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__le16 di_clusterofs;
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union {
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/* for the head cluster */
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__le32 blkaddr;
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/*
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* for the rest clusters
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* eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
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* [0] - pointing to the head cluster
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* [1] - pointing to the tail cluster
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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_VLE_LEGACY_INDEX_ALIGN(size) \
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(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
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sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
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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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/* file types used in inode_info->flags */
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enum {
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EROFS_FT_UNKNOWN,
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EROFS_FT_REG_FILE,
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EROFS_FT_DIR,
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EROFS_FT_CHRDEV,
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EROFS_FT_BLKDEV,
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EROFS_FT_FIFO,
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EROFS_FT_SOCK,
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EROFS_FT_SYMLINK,
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EROFS_FT_MAX
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};
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#define EROFS_NAME_LEN 255
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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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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 z_erofs_map_header) != 8);
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BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
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BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
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BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
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Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
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}
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#endif
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