[PREVIEW] [RFC PATCH 1/5] erofs-mkfs: add erofs on-disk layout
Gao Xiang
hsiangkao at aol.com
Sat Nov 17 21:02:04 AEDT 2018
On 2018/11/16 11:30, bluce.liguifu at huawei.com wrote:
> From: Li Guifu <bluce.liguifu at huawei.com>
>
> This patch adds a header file describing the erofs on-disk layout, which
> should be kept in line with the kernel implementation all the time.
>
> Signed-off-by: Li Guifu <bluce.liguifu at huawei.com>
> Signed-off-by: Miao Xie <miaoxie at huawei.com>
> Signed-off-by: Fang Wei <fangwei1 at huawei.com>
> ---
> erofs_fs.h | 298 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 298 insertions(+)
> create mode 100644 erofs_fs.h
>
> diff --git a/erofs_fs.h b/erofs_fs.h
> new file mode 100644
> index 0000000..c0b5510
> --- /dev/null
> +++ b/erofs_fs.h
> @@ -0,0 +1,298 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * erofs_fs.h
> + *
> + * Copyright (C) 2017-2018 HUAWEI, Inc.
> + * http://www.huawei.com/
> + * Created by Li Guifu <bluce.liguifu at huawei.com>
> + */
> +#ifndef __EROFS_FS_H
> +#define __EROFS_FS_H
> +
> +#include "erofs_types.h"
> +#define __packed __attribute__((__packed__))
> +
> +
> +/* 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 on-disk inode */
> +#define EROFS_INODE_LAYOUT_V1 0
> +/* 64 bytes on-disk inode */
> +#define EROFS_INODE_LAYOUT_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
> +
> +/* 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;
> +
> +/*
> + * Z_EROFS Variable-sized Logical Extent cluster type:
> + * 0 - literal (uncompressed) cluster
> + * 1 - compressed cluster (for the head logical cluster)
> + * 2 - compressed cluster (for the other logical clusters)
> + *
> + * In detail,
> + * 0 - literal (uncompressed) cluster,
> + * di_advise = 0
> + * di_clusterofs = the literal data offset of the cluster
> + * di_blkaddr = the blkaddr of the literal cluster
> + *
> + * 1 - compressed cluster (for the head logical cluster)
> + * di_advise = 1
> + * di_clusterofs = the decompressed data offset of the cluster
> + * di_blkaddr = the blkaddr of the compressed cluster
> + *
> + * 2 - compressed cluster (for the other logical clusters)
> + * di_advise = 2
> + * di_clusterofs =
> + * the decompressed data offset in its own head cluster
> + * di_u.delta[0] = distance to its corresponding head cluster
> + * di_u.delta[1] = distance to its corresponding tail cluster
> + * (di_advise could be 0, 1 or 2)
> + */
> +enum {
> + Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
> + Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
> + Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
> + Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
> + Z_EROFS_VLE_CLUSTER_TYPE_MAX
> +};
> +
> +#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2
> +#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0
> +
> +struct z_erofs_vle_decompressed_index {
> + __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 Z_EROFS_VLE_EXTENT_ALIGN(size) round_up(size, \
> + sizeof(struct z_erofs_vle_decompressed_index))
> +
> +/* 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
> +
> +/* check the EROFS on-disk layout strictly at compile time */
> +static inline void erofs_check_ondisk_layout_definitions(void)
> +{
> + BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
> + BUILD_BUG_ON(sizeof(struct erofs_inode_v1) != 32);
> + BUILD_BUG_ON(sizeof(struct erofs_inode_v2) != 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_extent_header) != 16);
> + BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
> + BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
> +
> + BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
> + Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
> +}
> +
> +#define EROFS_SB_SIZE sizeof(struct erofs_super_block)
how about directly using sizeof(struct erofs_super_block)? what is the benefit to
define this?
p.s. such the following mkfs stuffs should be moved into a new mkfs-specfic file,
(eg. internal.h or other names).
erofs_fs.h should be the same as the kernel implementation.
> +
> +#define EROFS_DECOMPR_IDX_SZ sizeof(struct z_erofs_vle_decompressed_index)
> +#define EROFS_DECOMPR_IDXS_PER_BLK (EROFS_BLKSIZE / EROFS_DECOMPR_IDX_SZ)
duplicate Definition.
> +
> +#define EROFS_INODE_V1_SIZE sizeof(struct erofs_inode_v1)
> +#define EROFS_INODE_V2_SIZE sizeof(struct erofs_inode_v2)
> +
> +#define EROFS_DIRENT_SIZE sizeof(struct erofs_dirent)
> +#define EROFS_DECOMPR_IDX_SZ sizeof(struct z_erofs_vle_decompressed_index)
> +#define EROFS_DECOMPR_IDXS_PER_BLK (EROFS_BLKSIZE / EROFS_DECOMPR_IDX_SZ)
> +
> +#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)
> +
> +#define EROFS_INLINE_GENERIC_ALIGN_SIZE (4)
> +#define EROFS_INLINE_INDEX_ALIGN_SIZE (8)
what are these two macros used for?
Thanks,
Gao Xiang
> +
> +#endif
> +
>
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