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14373711dd
linux/fs/erofs/erofs_fs.h
Gao Xiang 14373711dd erofs: add on-disk compression configurations 
Add a bitmap for available compression algorithms and a variable-sized
on-disk table for compression options in preparation for upcoming big
pcluster and LZMA algorithm, which follows the end of super block.

To parse the compression options, the bitmap is scanned one by one.
For each available algorithm, there is data followed by 2-byte `length'
correspondingly (it's enough for most cases, or entire fs blocks should
be used.)

With such available algorithm bitmap, kernel itself can also refuse to
mount such filesystem if any unsupported compression algorithm exists.

Note that COMPR_CFGS feature will be enabled with BIG_PCLUSTER.

Link: https://lore.kernel.org/r/20210329100012.12980-1-hsiangkao@aol.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
2021-03-29 18:01:42 +08:00

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/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
/*
* EROFS (Enhanced ROM File System) on-disk format definition
*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* https://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
#ifndef __EROFS_FS_H
#define __EROFS_FS_H
#define EROFS_SUPER_OFFSET 1024
#define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
/*
* Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
* be incompatible with this kernel version.
*/
#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001
#define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002
#define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING
#define EROFS_SB_EXTSLOT_SIZE 16
/* erofs on-disk super block (currently 128 bytes) */
struct erofs_super_block {
__le32 magic; /* file system magic number */
__le32 checksum; /* crc32c(super_block) */
__le32 feature_compat;
__u8 blkszbits; /* support block_size == PAGE_SIZE only */
__u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
__le16 root_nid; /* nid of root directory */
__le64 inos; /* total valid ino # (== f_files - f_favail) */
__le64 build_time; /* inode v1 time derivation */
__le32 build_time_nsec; /* inode v1 time derivation in nano scale */
__le32 blocks; /* used for statfs */
__le32 meta_blkaddr; /* start block address of metadata area */
__le32 xattr_blkaddr; /* start block address of shared xattr area */
__u8 uuid[16]; /* 128-bit uuid for volume */
__u8 volume_name[16]; /* volume name */
__le32 feature_incompat;
union {
/* bitmap for available compression algorithms */
__le16 available_compr_algs;
/* customized sliding window size instead of 64k by default */
__le16 lz4_max_distance;
} __packed u1;
__u8 reserved2[42];
};
/*
* erofs inode datalayout (i_format in on-disk inode):
* 0 - inode plain without inline data A:
* inode, [xattrs], ... | ... | no-holed data
* 1 - inode VLE compression B (legacy):
* inode, [xattrs], extents ... | ...
* 2 - inode plain with inline data C:
* inode, [xattrs], last_inline_data, ... | ... | no-holed data
* 3 - inode compression D:
* inode, [xattrs], map_header, extents ... | ...
* 4~7 - reserved
*/
enum {
EROFS_INODE_FLAT_PLAIN = 0,
EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1,
EROFS_INODE_FLAT_INLINE = 2,
EROFS_INODE_FLAT_COMPRESSION = 3,
EROFS_INODE_DATALAYOUT_MAX
};
static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
{
return datamode == EROFS_INODE_FLAT_COMPRESSION ||
datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
}
/* bit definitions of inode i_advise */
#define EROFS_I_VERSION_BITS 1
#define EROFS_I_DATALAYOUT_BITS 3
#define EROFS_I_VERSION_BIT 0
#define EROFS_I_DATALAYOUT_BIT 1
#define EROFS_I_ALL \
((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1)
/* 32-byte reduced form of an ondisk inode */
struct erofs_inode_compact {
__le16 i_format; /* inode format hints */
/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
__le16 i_xattr_icount;
__le16 i_mode;
__le16 i_nlink;
__le32 i_size;
__le32 i_reserved;
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;
__le32 i_ino; /* only used for 32-bit stat compatibility */
__le16 i_uid;
__le16 i_gid;
__le32 i_reserved2;
};
/* 32 bytes on-disk inode */
#define EROFS_INODE_LAYOUT_COMPACT 0
/* 64 bytes on-disk inode */
#define EROFS_INODE_LAYOUT_EXTENDED 1
/* 64-byte complete form of an ondisk inode */
struct erofs_inode_extended {
__le16 i_format; /* inode format hints */
/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
__le16 i_xattr_icount;
__le16 i_mode;
__le16 i_reserved;
__le64 i_size;
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;
/* only used for 32-bit stat compatibility */
__le32 i_ino;
__le32 i_uid;
__le32 i_gid;
__le64 i_ctime;
__le32 i_ctime_nsec;
__le32 i_nlink;
__u8 i_reserved2[16];
};
#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_reserved;
__u8 h_shared_count;
__u8 h_reserved2[7];
__le32 h_shared_xattrs[0]; /* shared xattr id array */
};
/* 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 */
};
static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
{
if (!i_xattr_icount)
return 0;
return sizeof(struct erofs_xattr_ibody_header) +
sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
}
#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
{
return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
e->e_name_len + le16_to_cpu(e->e_value_size));
}
/* available compression algorithm types (for h_algorithmtype) */
enum {
Z_EROFS_COMPRESSION_LZ4 = 0,
Z_EROFS_COMPRESSION_MAX
};
#define Z_EROFS_ALL_COMPR_ALGS (1 << (Z_EROFS_COMPRESSION_MAX - 1))
/* 14 bytes (+ length field = 16 bytes) */
struct z_erofs_lz4_cfgs {
__le16 max_distance;
u8 reserved[12];
} __packed;
/*
* bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
* e.g. for 4k logical cluster size, 4B if compacted 2B is off;
* (4B) + 2B + (4B) if compacted 2B is on.
*/
#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0
#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
struct z_erofs_map_header {
__le32 h_reserved1;
__le16 h_advise;
/*
* bit 0-3 : algorithm type of head 1 (logical cluster type 01);
* bit 4-7 : algorithm type of head 2 (logical cluster type 11).
*/
__u8 h_algorithmtype;
/*
* bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
* bit 3-4 : (physical - logical) cluster bits of head 1:
* For example, if logical clustersize = 4096, 1 for 8192.
* bit 5-7 : (physical - logical) cluster bits of head 2.
*/
__u8 h_clusterbits;
};
#define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8
/*
* Fixed-sized output compression ondisk 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 = 0,
Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1,
Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2,
Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3,
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;
};
#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
/* dirent sorts in alphabet order, thus we can do binary search */
struct erofs_dirent {
__le64 nid; /* node number */
__le16 nameoff; /* start offset of file name */
__u8 file_type; /* file type */
__u8 reserved; /* reserved */
} __packed;
/*
* EROFS file types should match generic FT_* types and
* it seems no need to add BUILD_BUG_ONs since potential
* unmatchness will break other fses as well...
*/
#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_compact) != 32);
BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 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 z_erofs_map_header) != 8);
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);
}
#endif
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