fs/erofs/erofs_fs.h

   1 /* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
   2 /*
   3  * Copyright (C) 2017-2018 HUAWEI, Inc.
   4  *             http://www.huawei.com/
   5  * Created by Gao Xiang <gaoxiang25@huawei.com>
   6  */
   7 #ifndef __EROFS_FS_H
   8 #define __EROFS_FS_H
   9
  10 /* Enhanced(Extended) ROM File System */
  11 #define EROFS_SUPER_OFFSET      1024
  12
  13 /*
  14  * Any bits that aren't in EROFS_ALL_REQUIREMENTS should be
  15  * incompatible with this kernel version.
  16  */
  17 #define EROFS_REQUIREMENT_LZ4_0PADDING  0x00000001
  18 #define EROFS_ALL_REQUIREMENTS          EROFS_REQUIREMENT_LZ4_0PADDING
  19
  20 /* 128-byte erofs on-disk super block */
  21 struct erofs_super_block {
  22         __le32 magic;           /* file system magic number */
  23         __le32 checksum;        /* crc32c(super_block) */
  24         __le32 features;        /* (aka. feature_compat) */
  25         __u8 blkszbits;         /* support block_size == PAGE_SIZE only */
  26         __u8 reserved;
  27
  28         __le16 root_nid;        /* nid of root directory */
  29         __le64 inos;            /* total valid ino # (== f_files - f_favail) */
  30
  31         __le64 build_time;      /* inode v1 time derivation */
  32         __le32 build_time_nsec; /* inode v1 time derivation in nano scale */
  33         __le32 blocks;          /* used for statfs */
  34         __le32 meta_blkaddr;    /* start block address of metadata area */
  35         __le32 xattr_blkaddr;   /* start block address of shared xattr area */
  36         __u8 uuid[16];          /* 128-bit uuid for volume */
  37         __u8 volume_name[16];   /* volume name */
  38         __le32 requirements;    /* (aka. feature_incompat) */
  39
  40         __u8 reserved2[44];
  41 } __packed;
  42
  43 /*
  44  * erofs inode data mapping:
  45  * 0 - inode plain without inline data A:
  46  * inode, [xattrs], ... | ... | no-holed data
  47  * 1 - inode VLE compression B (legacy):
  48  * inode, [xattrs], extents ... | ...
  49  * 2 - inode plain with inline data C:
  50  * inode, [xattrs], last_inline_data, ... | ... | no-holed data
  51  * 3 - inode compression D:
  52  * inode, [xattrs], map_header, extents ... | ...
  53  * 4~7 - reserved
  54  */
  55 enum {
  56         EROFS_INODE_FLAT_PLAIN,
  57         EROFS_INODE_FLAT_COMPRESSION_LEGACY,
  58         EROFS_INODE_FLAT_INLINE,
  59         EROFS_INODE_FLAT_COMPRESSION,
  60         EROFS_INODE_LAYOUT_MAX
  61 };
  62
  63 static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
  64 {
  65         if (datamode == EROFS_INODE_FLAT_COMPRESSION)
  66                 return true;
  67         return datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
  68 }
  69
  70 /* bit definitions of inode i_advise */
  71 #define EROFS_I_VERSION_BITS            1
  72 #define EROFS_I_DATA_MAPPING_BITS       3
  73
  74 #define EROFS_I_VERSION_BIT             0
  75 #define EROFS_I_DATA_MAPPING_BIT        1
  76
  77 /* 32-byte reduced form of an ondisk inode */
  78 struct erofs_inode_v1 {
  79         __le16 i_advise;        /* inode hints */
  80
  81 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
  82         __le16 i_xattr_icount;
  83         __le16 i_mode;
  84         __le16 i_nlink;
  85         __le32 i_size;
  86         __le32 i_reserved;
  87         union {
  88                 /* file total compressed blocks for data mapping 1 */
  89                 __le32 compressed_blocks;
  90                 __le32 raw_blkaddr;
  91
  92                 /* for device files, used to indicate old/new device # */
  93                 __le32 rdev;
  94         } i_u __packed;
  95         __le32 i_ino;           /* only used for 32-bit stat compatibility */
  96         __le16 i_uid;
  97         __le16 i_gid;
  98         __le32 i_reserved2;
  99 } __packed;
 100
 101 /* 32 bytes on-disk inode */
 102 #define EROFS_INODE_LAYOUT_V1   0
 103 /* 64 bytes on-disk inode */
 104 #define EROFS_INODE_LAYOUT_V2   1
 105
 106 /* 64-byte complete form of an ondisk inode */
 107 struct erofs_inode_v2 {
 108         __le16 i_advise;        /* inode hints */
 109
 110 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
 111         __le16 i_xattr_icount;
 112         __le16 i_mode;
 113         __le16 i_reserved;
 114         __le64 i_size;
 115         union {
 116                 /* file total compressed blocks for data mapping 1 */
 117                 __le32 compressed_blocks;
 118                 __le32 raw_blkaddr;
 119
 120                 /* for device files, used to indicate old/new device # */
 121                 __le32 rdev;
 122         } i_u __packed;
 123
 124         /* only used for 32-bit stat compatibility */
 125         __le32 i_ino;
 126
 127         __le32 i_uid;
 128         __le32 i_gid;
 129         __le64 i_ctime;
 130         __le32 i_ctime_nsec;
 131         __le32 i_nlink;
 132         __u8   i_reserved2[16];
 133 } __packed;
 134
 135 #define EROFS_MAX_SHARED_XATTRS         (128)
 136 /* h_shared_count between 129 ... 255 are special # */
 137 #define EROFS_SHARED_XATTR_EXTENT       (255)
 138
 139 /*
 140  * inline xattrs (n == i_xattr_icount):
 141  * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
 142  *          12 bytes           /                   \
 143  *                            /                     \
 144  *                           /-----------------------\
 145  *                           |  erofs_xattr_entries+ |
 146  *                           +-----------------------+
 147  * inline xattrs must starts in erofs_xattr_ibody_header,
 148  * for read-only fs, no need to introduce h_refcount
 149  */
 150 struct erofs_xattr_ibody_header {
 151         __le32 h_reserved;
 152         __u8   h_shared_count;
 153         __u8   h_reserved2[7];
 154         __le32 h_shared_xattrs[0];      /* shared xattr id array */
 155 } __packed;
 156
 157 /* Name indexes */
 158 #define EROFS_XATTR_INDEX_USER              1
 159 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS  2
 160 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
 161 #define EROFS_XATTR_INDEX_TRUSTED           4
 162 #define EROFS_XATTR_INDEX_LUSTRE            5
 163 #define EROFS_XATTR_INDEX_SECURITY          6
 164
 165 /* xattr entry (for both inline & shared xattrs) */
 166 struct erofs_xattr_entry {
 167         __u8   e_name_len;      /* length of name */
 168         __u8   e_name_index;    /* attribute name index */
 169         __le16 e_value_size;    /* size of attribute value */
 170         /* followed by e_name and e_value */
 171         char   e_name[0];       /* attribute name */
 172 } __packed;
 173
 174 #define ondisk_xattr_ibody_size(count)  ({\
 175         u32 __count = le16_to_cpu(count); \
 176         ((__count) == 0) ? 0 : \
 177         sizeof(struct erofs_xattr_ibody_header) + \
 178                 sizeof(__u32) * ((__count) - 1); })
 179
 180 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
 181 #define EROFS_XATTR_ENTRY_SIZE(entry) EROFS_XATTR_ALIGN( \
 182         sizeof(struct erofs_xattr_entry) + \
 183         (entry)->e_name_len + le16_to_cpu((entry)->e_value_size))
 184
 185 /* available compression algorithm types */
 186 enum {
 187         Z_EROFS_COMPRESSION_LZ4,
 188         Z_EROFS_COMPRESSION_MAX
 189 };
 190
 191 /*
 192  * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
 193  *  e.g. for 4k logical cluster size,      4B        if compacted 2B is off;
 194  *                                  (4B) + 2B + (4B) if compacted 2B is on.
 195  */
 196 #define Z_EROFS_ADVISE_COMPACTED_2B_BIT         0
 197
 198 #define Z_EROFS_ADVISE_COMPACTED_2B     (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
 199
 200 struct z_erofs_map_header {
 201         __le32  h_reserved1;
 202         __le16  h_advise;
 203         /*
 204          * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
 205          * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
 206          */
 207         __u8    h_algorithmtype;
 208         /*
 209          * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
 210          * bit 3-4 : (physical - logical) cluster bits of head 1:
 211          *       For example, if logical clustersize = 4096, 1 for 8192.
 212          * bit 5-7 : (physical - logical) cluster bits of head 2.
 213          */
 214         __u8    h_clusterbits;
 215 };
 216
 217 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING       8
 218
 219 /*
 220  * Z_EROFS Variable-sized Logical Extent cluster type:
 221  *    0 - literal (uncompressed) cluster
 222  *    1 - compressed cluster (for the head logical cluster)
 223  *    2 - compressed cluster (for the other logical clusters)
 224  *
 225  * In detail,
 226  *    0 - literal (uncompressed) cluster,
 227  *        di_advise = 0
 228  *        di_clusterofs = the literal data offset of the cluster
 229  *        di_blkaddr = the blkaddr of the literal cluster
 230  *
 231  *    1 - compressed cluster (for the head logical cluster)
 232  *        di_advise = 1
 233  *        di_clusterofs = the decompressed data offset of the cluster
 234  *        di_blkaddr = the blkaddr of the compressed cluster
 235  *
 236  *    2 - compressed cluster (for the other logical clusters)
 237  *        di_advise = 2
 238  *        di_clusterofs =
 239  *           the decompressed data offset in its own head cluster
 240  *        di_u.delta[0] = distance to its corresponding head cluster
 241  *        di_u.delta[1] = distance to its corresponding tail cluster
 242  *                (di_advise could be 0, 1 or 2)
 243  */
 244 enum {
 245         Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
 246         Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
 247         Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
 248         Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
 249         Z_EROFS_VLE_CLUSTER_TYPE_MAX
 250 };
 251
 252 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS        2
 253 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT         0
 254
 255 struct z_erofs_vle_decompressed_index {
 256         __le16 di_advise;
 257         /* where to decompress in the head cluster */
 258         __le16 di_clusterofs;
 259
 260         union {
 261                 /* for the head cluster */
 262                 __le32 blkaddr;
 263                 /*
 264                  * for the rest clusters
 265                  * eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
 266                  * [0] - pointing to the head cluster
 267                  * [1] - pointing to the tail cluster
 268                  */
 269                 __le16 delta[2];
 270         } di_u __packed;
 271 } __packed;
 272
 273 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
 274         (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
 275          sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
 276
 277 /* dirent sorts in alphabet order, thus we can do binary search */
 278 struct erofs_dirent {
 279         __le64 nid;     /* node number */
 280         __le16 nameoff; /* start offset of file name */
 281         __u8 file_type; /* file type */
 282         __u8 reserved;  /* reserved */
 283 } __packed;
 284
 285 /*
 286  * EROFS file types should match generic FT_* types and
 287  * it seems no need to add BUILD_BUG_ONs since potential
 288  * unmatchness will break other fses as well...
 289  */
 290
 291 #define EROFS_NAME_LEN      255
 292
 293 /* check the EROFS on-disk layout strictly at compile time */
 294 static inline void erofs_check_ondisk_layout_definitions(void)
 295 {
 296         BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
 297         BUILD_BUG_ON(sizeof(struct erofs_inode_v1) != 32);
 298         BUILD_BUG_ON(sizeof(struct erofs_inode_v2) != 64);
 299         BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
 300         BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
 301         BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
 302         BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
 303         BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
 304
 305         BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
 306                      Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
 307 }
 308
 309 #endif
 310