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Gao Xianggregkh
Gao Xiang
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gregkh
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staging: erofs: add on-disk layout
This commit adds the on-disk layout header file of erofs. Note that the on-disk layout is still WIP, and some fields are reserved for the future use by design. Any comments are welcome. Thanks-to: Li Guifu <liguifu2@huawei.com> Thanks-to: Sun Qiuyang <sunqiuyang@huawei.com> Signed-off-by: Miao Xie <miaoxie@huawei.com> Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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‎drivers/staging/erofs/erofs_fs.h

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/* SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
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*
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* linux/drivers/staging/erofs/erofs_fs.h
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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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* This file is dual-licensed; you may select either the GNU General Public
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* License version 2 or Apache License, Version 2.0. See the file COPYING
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* in the main directory of the Linux distribution for more details.
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*/
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#ifndef __EROFS_FS_H
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#define __EROFS_FS_H
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/* Enhanced(Extended) ROM File System */
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#define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2
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#define EROFS_SUPER_OFFSET 1024
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struct erofs_super_block {
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/* 0 */__le32 magic; /* in the little endian */
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/* 4 */__le32 checksum; /* crc32c(super_block) */
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/* 8 */__le32 features;
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/* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only */
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/* 13 */__u8 reserved;
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/* 14 */__le16 root_nid;
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/* 16 */__le64 inos; /* total valid ino # (== f_files - f_favail) */
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/* 24 */__le64 build_time; /* inode v1 time derivation */
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/* 32 */__le32 build_time_nsec;
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/* 36 */__le32 blocks; /* used for statfs */
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/* 40 */__le32 meta_blkaddr;
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/* 44 */__le32 xattr_blkaddr;
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/* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */
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/* 64 */__u8 volume_name[16]; /* volume name */
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/* 80 */__u8 reserved2[48]; /* 128 bytes */
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} __packed;
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#define __EROFS_BIT(_prefix, _cur, _pre) enum { \
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_prefix ## _cur ## _BIT = _prefix ## _pre ## _BIT + \
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_prefix ## _pre ## _BITS }
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/*
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* erofs inode data mapping:
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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:
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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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* 3~7 - reserved
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*/
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enum {
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EROFS_INODE_LAYOUT_PLAIN,
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EROFS_INODE_LAYOUT_COMPRESSION,
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EROFS_INODE_LAYOUT_INLINE,
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EROFS_INODE_LAYOUT_MAX
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};
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#define EROFS_I_VERSION_BITS 1
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#define EROFS_I_DATA_MAPPING_BITS 3
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#define EROFS_I_VERSION_BIT 0
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__EROFS_BIT(EROFS_I_, DATA_MAPPING, VERSION);
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struct erofs_inode_v1 {
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/* 0 */__le16 i_advise;
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/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
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/* 2 */__le16 i_xattr_icount;
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/* 4 */__le16 i_mode;
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/* 6 */__le16 i_nlink;
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/* 8 */__le32 i_size;
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/* 12 */__le32 i_reserved;
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/* 16 */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 __packed;
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/* 20 */__le32 i_ino; /* only used for 32-bit stat compatibility */
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/* 24 */__le16 i_uid;
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/* 26 */__le16 i_gid;
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/* 28 */__le32 i_checksum;
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} __packed;
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/* 32 bytes on-disk inode */
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#define EROFS_INODE_LAYOUT_V1 0
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/* 64 bytes on-disk inode */
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#define EROFS_INODE_LAYOUT_V2 1
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struct erofs_inode_v2 {
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__le16 i_advise;
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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; /* 8 bytes */
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__le64 i_size; /* 16 bytes */
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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 __packed;
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/* only used for 32-bit stat compatibility */
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__le32 i_ino; /* 24 bytes */
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__le32 i_uid;
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__le32 i_gid;
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__le64 i_ctime; /* 32 bytes */
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__le32 i_ctime_nsec;
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__le32 i_nlink;
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__u8 i_reserved2[12];
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__le32 i_checksum; /* 64 bytes */
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} __packed;
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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_checksum;
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__u8 h_shared_count;
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__u8 h_reserved[7];
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__le32 h_shared_xattrs[0]; /* shared xattr id array */
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} __packed;
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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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} __packed;
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#define ondisk_xattr_ibody_size(count) ({\
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u32 __count = le16_to_cpu(count); \
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((__count) == 0) ? 0 : \
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sizeof(struct erofs_xattr_ibody_header) + \
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sizeof(__u32) * ((__count) - 1); })
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#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
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#define EROFS_XATTR_ENTRY_SIZE(entry) EROFS_XATTR_ALIGN( \
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sizeof(struct erofs_xattr_entry) + \
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(entry)->e_name_len + le16_to_cpu((entry)->e_value_size))
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/* have to be aligned with 8 bytes on disk */
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struct erofs_extent_header {
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__le32 eh_checksum;
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__le32 eh_reserved[3];
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} __packed;
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/*
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* Z_EROFS Variable-sized 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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#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 __packed; /* 8 bytes */
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} __packed;
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#define Z_EROFS_VLE_EXTENT_ALIGN(size) round_up(size, \
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sizeof(struct z_erofs_vle_decompressed_index))
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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; /* 0, node number */
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__le16 nameoff; /* 8, start offset of file name */
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__u8 file_type; /* 10, file type */
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__u8 reserved; /* 11, 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_v1) != 32);
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BUILD_BUG_ON(sizeof(struct erofs_inode_v2) != 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_extent_header) != 16);
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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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}
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#endif
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