1 /* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
2 /*
3 * EROFS (Enhanced ROM File System) on-disk format definition
4 *
5 * Copyright (C) 2017-2018 HUAWEI, Inc.
6 * https://www.huawei.com/
7 * Copyright (C) 2021, Alibaba Cloud
8 */
9 #ifndef __EROFS_FS_H
10 #define __EROFS_FS_H
11
12 #define EROFS_SUPER_OFFSET 1024
13
14 #define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
15
16 /*
17 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
18 * be incompatible with this kernel version.
19 */
20 #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001
21 #define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002
22 #define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002
23 #define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004
24 #define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008
25 #define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008
26 #define EROFS_ALL_FEATURE_INCOMPAT \
27 (EROFS_FEATURE_INCOMPAT_LZ4_0PADDING | \
28 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \
29 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \
30 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \
31 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \
32 EROFS_FEATURE_INCOMPAT_COMPR_HEAD2)
33
34 #define EROFS_SB_EXTSLOT_SIZE 16
35
36 struct erofs_deviceslot {
37 union {
38 u8 uuid[16]; /* used for device manager later */
39 u8 userdata[64]; /* digest(sha256), etc. */
40 } u;
41 __le32 blocks; /* total fs blocks of this device */
42 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */
43 u8 reserved[56];
44 };
45 #define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot)
46
47 /* erofs on-disk super block (currently 128 bytes) */
48 struct erofs_super_block {
49 __le32 magic; /* file system magic number */
50 __le32 checksum; /* crc32c(super_block) */
51 __le32 feature_compat;
52 __u8 blkszbits; /* support block_size == PAGE_SIZE only */
53 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
54
55 __le16 root_nid; /* nid of root directory */
56 __le64 inos; /* total valid ino # (== f_files - f_favail) */
57
58 __le64 build_time; /* inode v1 time derivation */
59 __le32 build_time_nsec; /* inode v1 time derivation in nano scale */
60 __le32 blocks; /* used for statfs */
61 __le32 meta_blkaddr; /* start block address of metadata area */
62 __le32 xattr_blkaddr; /* start block address of shared xattr area */
63 __u8 uuid[16]; /* 128-bit uuid for volume */
64 __u8 volume_name[16]; /* volume name */
65 __le32 feature_incompat;
66 union {
67 /* bitmap for available compression algorithms */
68 __le16 available_compr_algs;
69 /* customized sliding window size instead of 64k by default */
70 __le16 lz4_max_distance;
71 } __packed u1;
72 __le16 extra_devices; /* # of devices besides the primary device */
73 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */
74 __u8 reserved2[38];
75 };
76
77 /*
78 * erofs inode datalayout (i_format in on-disk inode):
79 * 0 - inode plain without inline data A:
80 * inode, [xattrs], ... | ... | no-holed data
81 * 1 - inode VLE compression B (legacy):
82 * inode, [xattrs], extents ... | ...
83 * 2 - inode plain with inline data C:
84 * inode, [xattrs], last_inline_data, ... | ... | no-holed data
85 * 3 - inode compression D:
86 * inode, [xattrs], map_header, extents ... | ...
87 * 4 - inode chunk-based E:
88 * inode, [xattrs], chunk indexes ... | ...
89 * 5~7 - reserved
90 */
91 enum {
92 EROFS_INODE_FLAT_PLAIN = 0,
93 EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1,
94 EROFS_INODE_FLAT_INLINE = 2,
95 EROFS_INODE_FLAT_COMPRESSION = 3,
96 EROFS_INODE_CHUNK_BASED = 4,
97 EROFS_INODE_DATALAYOUT_MAX
98 };
99
erofs_inode_is_data_compressed(unsigned int datamode)100 static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
101 {
102 return datamode == EROFS_INODE_FLAT_COMPRESSION ||
103 datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
104 }
105
106 /* bit definitions of inode i_advise */
107 #define EROFS_I_VERSION_BITS 1
108 #define EROFS_I_DATALAYOUT_BITS 3
109
110 #define EROFS_I_VERSION_BIT 0
111 #define EROFS_I_DATALAYOUT_BIT 1
112
113 #define EROFS_I_ALL \
114 ((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1)
115
116 /* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */
117 #define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F
118 /* with chunk indexes or just a 4-byte blkaddr array */
119 #define EROFS_CHUNK_FORMAT_INDEXES 0x0020
120
121 #define EROFS_CHUNK_FORMAT_ALL \
122 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES)
123
124 struct erofs_inode_chunk_info {
125 __le16 format; /* chunk blkbits, etc. */
126 __le16 reserved;
127 };
128
129 /* 32-byte reduced form of an ondisk inode */
130 struct erofs_inode_compact {
131 __le16 i_format; /* inode format hints */
132
133 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
134 __le16 i_xattr_icount;
135 __le16 i_mode;
136 __le16 i_nlink;
137 __le32 i_size;
138 __le32 i_reserved;
139 union {
140 /* file total compressed blocks for data mapping 1 */
141 __le32 compressed_blocks;
142 __le32 raw_blkaddr;
143
144 /* for device files, used to indicate old/new device # */
145 __le32 rdev;
146
147 /* for chunk-based files, it contains the summary info */
148 struct erofs_inode_chunk_info c;
149 } i_u;
150 __le32 i_ino; /* only used for 32-bit stat compatibility */
151 __le16 i_uid;
152 __le16 i_gid;
153 __le32 i_reserved2;
154 };
155
156 /* 32 bytes on-disk inode */
157 #define EROFS_INODE_LAYOUT_COMPACT 0
158 /* 64 bytes on-disk inode */
159 #define EROFS_INODE_LAYOUT_EXTENDED 1
160
161 /* 64-byte complete form of an ondisk inode */
162 struct erofs_inode_extended {
163 __le16 i_format; /* inode format hints */
164
165 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
166 __le16 i_xattr_icount;
167 __le16 i_mode;
168 __le16 i_reserved;
169 __le64 i_size;
170 union {
171 /* file total compressed blocks for data mapping 1 */
172 __le32 compressed_blocks;
173 __le32 raw_blkaddr;
174
175 /* for device files, used to indicate old/new device # */
176 __le32 rdev;
177
178 /* for chunk-based files, it contains the summary info */
179 struct erofs_inode_chunk_info c;
180 } i_u;
181
182 /* only used for 32-bit stat compatibility */
183 __le32 i_ino;
184
185 __le32 i_uid;
186 __le32 i_gid;
187 __le64 i_ctime;
188 __le32 i_ctime_nsec;
189 __le32 i_nlink;
190 __u8 i_reserved2[16];
191 };
192
193 #define EROFS_MAX_SHARED_XATTRS (128)
194 /* h_shared_count between 129 ... 255 are special # */
195 #define EROFS_SHARED_XATTR_EXTENT (255)
196
197 /*
198 * inline xattrs (n == i_xattr_icount):
199 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
200 * 12 bytes / \
201 * / \
202 * /-----------------------\
203 * | erofs_xattr_entries+ |
204 * +-----------------------+
205 * inline xattrs must starts in erofs_xattr_ibody_header,
206 * for read-only fs, no need to introduce h_refcount
207 */
208 struct erofs_xattr_ibody_header {
209 __le32 h_reserved;
210 __u8 h_shared_count;
211 __u8 h_reserved2[7];
212 __le32 h_shared_xattrs[0]; /* shared xattr id array */
213 };
214
215 /* Name indexes */
216 #define EROFS_XATTR_INDEX_USER 1
217 #define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2
218 #define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
219 #define EROFS_XATTR_INDEX_TRUSTED 4
220 #define EROFS_XATTR_INDEX_LUSTRE 5
221 #define EROFS_XATTR_INDEX_SECURITY 6
222
223 /* xattr entry (for both inline & shared xattrs) */
224 struct erofs_xattr_entry {
225 __u8 e_name_len; /* length of name */
226 __u8 e_name_index; /* attribute name index */
227 __le16 e_value_size; /* size of attribute value */
228 /* followed by e_name and e_value */
229 char e_name[0]; /* attribute name */
230 };
231
erofs_xattr_ibody_size(__le16 i_xattr_icount)232 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
233 {
234 if (!i_xattr_icount)
235 return 0;
236
237 return sizeof(struct erofs_xattr_ibody_header) +
238 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
239 }
240
241 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
242
erofs_xattr_entry_size(struct erofs_xattr_entry * e)243 static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
244 {
245 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
246 e->e_name_len + le16_to_cpu(e->e_value_size));
247 }
248
249 /* represent a zeroed chunk (hole) */
250 #define EROFS_NULL_ADDR -1
251
252 /* 4-byte block address array */
253 #define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32)
254
255 /* 8-byte inode chunk indexes */
256 struct erofs_inode_chunk_index {
257 __le16 advise; /* always 0, don't care for now */
258 __le16 device_id; /* back-end storage id (with bits masked) */
259 __le32 blkaddr; /* start block address of this inode chunk */
260 };
261
262 /* maximum supported size of a physical compression cluster */
263 #define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024)
264
265 /* available compression algorithm types (for h_algorithmtype) */
266 enum {
267 Z_EROFS_COMPRESSION_LZ4 = 0,
268 Z_EROFS_COMPRESSION_LZMA = 1,
269 Z_EROFS_COMPRESSION_MAX
270 };
271 #define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1)
272
273 /* 14 bytes (+ length field = 16 bytes) */
274 struct z_erofs_lz4_cfgs {
275 __le16 max_distance;
276 __le16 max_pclusterblks;
277 u8 reserved[10];
278 } __packed;
279
280 /* 14 bytes (+ length field = 16 bytes) */
281 struct z_erofs_lzma_cfgs {
282 __le32 dict_size;
283 __le16 format;
284 u8 reserved[8];
285 } __packed;
286
287 #define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE)
288
289 /*
290 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
291 * e.g. for 4k logical cluster size, 4B if compacted 2B is off;
292 * (4B) + 2B + (4B) if compacted 2B is on.
293 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
294 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
295 */
296 #define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
297 #define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
298 #define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004
299
300 struct z_erofs_map_header {
301 __le32 h_reserved1;
302 __le16 h_advise;
303 /*
304 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
305 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
306 */
307 __u8 h_algorithmtype;
308 /*
309 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
310 * bit 3-7 : reserved.
311 */
312 __u8 h_clusterbits;
313 };
314
315 #define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8
316
317 /*
318 * Fixed-sized output compression on-disk logical cluster type:
319 * 0 - literal (uncompressed) lcluster
320 * 1,3 - compressed lcluster (for HEAD lclusters)
321 * 2 - compressed lcluster (for NONHEAD lclusters)
322 *
323 * In detail,
324 * 0 - literal (uncompressed) lcluster,
325 * di_advise = 0
326 * di_clusterofs = the literal data offset of the lcluster
327 * di_blkaddr = the blkaddr of the literal pcluster
328 *
329 * 1,3 - compressed lcluster (for HEAD lclusters)
330 * di_advise = 1 or 3
331 * di_clusterofs = the decompressed data offset of the lcluster
332 * di_blkaddr = the blkaddr of the compressed pcluster
333 *
334 * 2 - compressed lcluster (for NONHEAD lclusters)
335 * di_advise = 2
336 * di_clusterofs =
337 * the decompressed data offset in its own HEAD lcluster
338 * di_u.delta[0] = distance to this HEAD lcluster
339 * di_u.delta[1] = distance to the next HEAD lcluster
340 */
341 enum {
342 Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0,
343 Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 = 1,
344 Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2,
345 Z_EROFS_VLE_CLUSTER_TYPE_HEAD2 = 3,
346 Z_EROFS_VLE_CLUSTER_TYPE_MAX
347 };
348
349 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2
350 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0
351
352 /*
353 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
354 * compressed block count of a compressed extent (in logical clusters, aka.
355 * block count of a pcluster).
356 */
357 #define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11)
358
359 struct z_erofs_vle_decompressed_index {
360 __le16 di_advise;
361 /* where to decompress in the head cluster */
362 __le16 di_clusterofs;
363
364 union {
365 /* for the head cluster */
366 __le32 blkaddr;
367 /*
368 * for the rest clusters
369 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
370 * [0] - pointing to the head cluster
371 * [1] - pointing to the tail cluster
372 */
373 __le16 delta[2];
374 } di_u;
375 };
376
377 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
378 (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
379 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
380
381 /* dirent sorts in alphabet order, thus we can do binary search */
382 struct erofs_dirent {
383 __le64 nid; /* node number */
384 __le16 nameoff; /* start offset of file name */
385 __u8 file_type; /* file type */
386 __u8 reserved; /* reserved */
387 } __packed;
388
389 /*
390 * EROFS file types should match generic FT_* types and
391 * it seems no need to add BUILD_BUG_ONs since potential
392 * unmatchness will break other fses as well...
393 */
394
395 #define EROFS_NAME_LEN 255
396
397 /* check the EROFS on-disk layout strictly at compile time */
erofs_check_ondisk_layout_definitions(void)398 static inline void erofs_check_ondisk_layout_definitions(void)
399 {
400 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
401 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
402 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
403 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
404 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
405 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4);
406 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8);
407 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
408 BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
409 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
410 /* keep in sync between 2 index structures for better extendibility */
411 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) !=
412 sizeof(struct z_erofs_vle_decompressed_index));
413 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
414
415 BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
416 Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
417 }
418
419 #endif
420