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@xxxxxxxxxx> Thanks-to: Sun Qiuyang <sunqiuyang@xxxxxxxxxx> Signed-off-by: Miao Xie <miaoxie@xxxxxxxxxx> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx> --- fs/erofs/erofs_fs.h | 258 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 258 insertions(+) create mode 100644 fs/erofs/erofs_fs.h diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h new file mode 100644 index 0000000..c08d982 --- /dev/null +++ b/fs/erofs/erofs_fs.h @@ -0,0 +1,258 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * linux/fs/erofs/erofs_fs.h + * + * Copyright (C) 2017-2018 HUAWEI, Inc. + * http://www.huawei.com/ + * Created by Gao Xiang <gaoxiang25@xxxxxxxxxx> + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of the Linux + * distribution for more details. + */ +#ifndef __EROFS_FS_H +#define __EROFS_FS_H + +/* Enhanced(Extended) ROM File System */ +#define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2 +#define EROFS_SUPER_OFFSET 1024 + +struct erofs_super_block { +/* 0 */__le32 magic; /* in the little endian */ +/* 4 */__le32 checksum; /* crc32c(super_block) */ +/* 8 */__le32 features; +/* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only */ +/* 13 */__u8 reserved; + +/* 14 */__le16 root_nid; +/* 16 */__le64 inos; /* total valid ino # (== f_files - f_favail) */ + +/* 24 */__le64 build_time; /* inode v1 time derivation */ +/* 32 */__le32 build_time_nsec; +/* 36 */__le32 blocks; /* used for statfs */ +/* 40 */__le32 meta_blkaddr; +/* 44 */__le32 xattr_blkaddr; +/* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */ +/* 64 */__u8 volume_name[16]; /* volume name */ + +/* 80 */__u8 reserved2[48]; /* 128 bytes */ +} __packed; + +#define __EROFS_BIT(_prefix, _cur, _pre) enum { \ + _prefix ## _cur ## _BIT = _prefix ## _pre ## _BIT + \ + _prefix ## _pre ## _BITS } + +/* + * erofs inode data mapping: + * 0 - inode plain without inline data A: + * inode, [xattrs], ... | ... | no-holed data + * 1 - inode VLE compression B: + * inode, [xattrs], extents ... | ... + * 2 - inode plain with inline data C: + * inode, [xattrs], last_inline_data, ... | ... | no-holed data + * 3~7 - reserved + */ +enum { + EROFS_INODE_LAYOUT_PLAIN, + EROFS_INODE_LAYOUT_COMPRESSION, + EROFS_INODE_LAYOUT_INLINE, + EROFS_INODE_LAYOUT_MAX +}; +#define EROFS_I_VERSION_BITS 1 +#define EROFS_I_DATA_MAPPING_BITS 3 + +#define EROFS_I_VERSION_BIT 0 +__EROFS_BIT(EROFS_I_, DATA_MAPPING, VERSION); + +struct erofs_inode_v1 { +/* 0 */__le16 i_advise; + +/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ +/* 2 */__le16 i_xattr_icount; +/* 4 */__le16 i_mode; +/* 6 */__le16 i_nlink; +/* 8 */__le32 i_size; +/* 12 */__le32 i_reserved; +/* 16 */union { + /* file total compressed blocks for data mapping 1 */ + __le32 compressed_blocks; + __le32 raw_blkaddr; + + /* for device files, used to indicate old/new device # */ + __le32 rdev; + } i_u __packed; +/* 20 */__le32 i_ino; /* only used for 32-bit stat compatibility */ +/* 24 */__le16 i_uid; +/* 26 */__le16 i_gid; +/* 28 */__le32 i_checksum; +} __packed; + +/* 32 bytes inode */ +#define EROFS_INODE_V1 0 +/* 64 bytes inode */ +#define EROFS_INODE_V2 1 + +struct erofs_inode_v2 { + __le16 i_advise; + + /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ + __le16 i_xattr_icount; + __le16 i_mode; + __le16 i_reserved; /* 8 bytes */ + __le64 i_size; /* 16 bytes */ + union { + /* file total compressed blocks for data mapping 1 */ + __le32 compressed_blocks; + __le32 raw_blkaddr; + + /* for device files, used to indicate old/new device # */ + __le32 rdev; + } i_u __packed; + + /* only used for 32-bit stat compatibility */ + __le32 i_ino; /* 24 bytes */ + + __le32 i_uid; + __le32 i_gid; + __le64 i_ctime; /* 32 bytes */ + __le32 i_ctime_nsec; + __le32 i_nlink; + __u8 i_reserved2[12]; + __le32 i_checksum; /* 64 bytes */ +} __packed; + +#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_checksum; + __u8 h_shared_count; + __u8 h_reserved[7]; + __le32 h_shared_xattrs[0]; /* shared xattr id array */ +} __packed; + +/* 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 +#define EROFS_XATTR_INDEX_ADVISE 7 + +/* xattr entry (for both inline & shared xattrs) */ +struct erofs_xattr_entry { + __u8 e_name_len; /* length of name */ + __u8 e_name_index; /* attribute name index */ + __le16 e_value_size; /* size of attribute value */ + /* followed by e_name and e_value */ + char e_name[0]; /* attribute name */ +} __packed; + +#define ondisk_xattr_ibody_size(count) ({\ + u32 __count = le16_to_cpu(count); \ + ((__count) == 0) ? 0 : \ + sizeof(struct erofs_xattr_ibody_header) + \ + sizeof(__u32) * ((__count) - 1); }) + +#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) +#define EROFS_XATTR_ENTRY_SIZE(entry) EROFS_XATTR_ALIGN( \ + sizeof(struct erofs_xattr_entry) + \ + (entry)->e_name_len + le16_to_cpu((entry)->e_value_size)) + +/* have to be aligned with 8 bytes on disk */ +struct erofs_extent_header { + __le32 eh_checksum; + __le32 eh_reserved[3]; +} __packed; + +/* + * EROFS Variable-sized Logical Extent cluster type: + * 0 - uncompressed logical cluster + * 1 - compressed logical cluster (for the head logical cluster) + * 2 - compressed logical cluster (for the rest logical clusters) + * For details: + * for the uncompressed logical cluster, + * di_advise = 0 + * di_clusterofs = + * the uncompressed data offset of the cluster + * di_blkaddr = the blkaddr of the uncompressed cluster + * for the compressed head logical cluster, + * di_advise = 1 + * di_clusterofs = + * the decompressed data offset of the cluster + * di_blkaddr = the blkaddr of the compressed cluster + * for the rest logical clusters, + * di_advise = 2 + * di_clusterofs = + * the decompressed data offset in the head cluster + * di_u.delta[0] = pointing to the head cluster + * di_u.delta[1] = pointing to the tail cluster + * (di_advise could be 0, 1 or 2) + */ +#define EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 +#define EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 + +struct erofs_decompressed_index_vle { + __le16 di_advise; + /* where to decompress in the head cluster */ + __le16 di_clusterofs; + + union { + /* for the head cluster */ + __le32 blkaddr; + /* + * for the rest clusters + * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) + * [0] - pointing to the head cluster + * [1] - pointing to the tail cluster + */ + __le16 delta[2]; + } di_u __packed; /* 8 bytes */ +} __packed; + +#define EROFS_VLE_EXTENT_ALIGN(size) round_up(size, \ + sizeof(struct erofs_decompressed_index_vle)) + +#define ondisk_extent_size(data_mapping_mode, count) \ + ((data_mapping_mode) == EROFS_INODE_LAYOUT_COMPRESSION ? \ + (sizeof(struct erofs_extent_header) + \ + sizeof(__u32) * le32_to_cpu(count)) : 0) + +/* dirent sorts in alphabet order, thus we can do binary search */ +struct erofs_dirent { + __le64 nid; /* 0, node number */ + __le16 nameoff; /* 8, start offset of file name */ + __u8 file_type; /* 10, file type */ + __u8 reserved; /* 11, reserved */ +} __packed; + +/* file types used in inode_info->flags */ +enum { + EROFS_FT_UNKNOWN, + EROFS_FT_REG_FILE, + EROFS_FT_DIR, + EROFS_FT_CHRDEV, + EROFS_FT_BLKDEV, + EROFS_FT_FIFO, + EROFS_FT_SOCK, + EROFS_FT_SYMLINK, + EROFS_FT_MAX +}; + +#define EROFS_NAME_LEN 255 + +#endif + -- 1.9.1
