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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#define EROFS_FEATURE_COMPAT_MTIME 0x00000002
16#define EROFS_FEATURE_COMPAT_XATTR_FILTER 0x00000004
17
18/*
19 * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
20 * be incompatible with this kernel version.
21 */
22#define EROFS_FEATURE_INCOMPAT_ZERO_PADDING 0x00000001
23#define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002
24#define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002
25#define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE 0x00000004
26#define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE 0x00000008
27#define EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 0x00000008
28#define EROFS_FEATURE_INCOMPAT_ZTAILPACKING 0x00000010
29#define EROFS_FEATURE_INCOMPAT_FRAGMENTS 0x00000020
30#define EROFS_FEATURE_INCOMPAT_DEDUPE 0x00000020
31#define EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES 0x00000040
32#define EROFS_ALL_FEATURE_INCOMPAT \
33 (EROFS_FEATURE_INCOMPAT_ZERO_PADDING | \
34 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \
35 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \
36 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \
37 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE | \
38 EROFS_FEATURE_INCOMPAT_COMPR_HEAD2 | \
39 EROFS_FEATURE_INCOMPAT_ZTAILPACKING | \
40 EROFS_FEATURE_INCOMPAT_FRAGMENTS | \
41 EROFS_FEATURE_INCOMPAT_DEDUPE | \
42 EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES)
43
44#define EROFS_SB_EXTSLOT_SIZE 16
45
46struct erofs_deviceslot {
47 u8 tag[64]; /* digest(sha256), etc. */
48 __le32 blocks; /* total fs blocks of this device */
49 __le32 mapped_blkaddr; /* map starting at mapped_blkaddr */
50 u8 reserved[56];
51};
52#define EROFS_DEVT_SLOT_SIZE sizeof(struct erofs_deviceslot)
53
54/* erofs on-disk super block (currently 128 bytes) */
55struct erofs_super_block {
56 __le32 magic; /* file system magic number */
57 __le32 checksum; /* crc32c(super_block) */
58 __le32 feature_compat;
59 __u8 blkszbits; /* filesystem block size in bit shift */
60 __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
61
62 __le16 root_nid; /* nid of root directory */
63 __le64 inos; /* total valid ino # (== f_files - f_favail) */
64
65 __le64 build_time; /* compact inode time derivation */
66 __le32 build_time_nsec; /* compact inode time derivation in ns scale */
67 __le32 blocks; /* used for statfs */
68 __le32 meta_blkaddr; /* start block address of metadata area */
69 __le32 xattr_blkaddr; /* start block address of shared xattr area */
70 __u8 uuid[16]; /* 128-bit uuid for volume */
71 __u8 volume_name[16]; /* volume name */
72 __le32 feature_incompat;
73 union {
74 /* bitmap for available compression algorithms */
75 __le16 available_compr_algs;
76 /* customized sliding window size instead of 64k by default */
77 __le16 lz4_max_distance;
78 } __packed u1;
79 __le16 extra_devices; /* # of devices besides the primary device */
80 __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */
81 __u8 dirblkbits; /* directory block size in bit shift */
82 __u8 xattr_prefix_count; /* # of long xattr name prefixes */
83 __le32 xattr_prefix_start; /* start of long xattr prefixes */
84 __le64 packed_nid; /* nid of the special packed inode */
85 __u8 xattr_filter_reserved; /* reserved for xattr name filter */
86 __u8 reserved2[23];
87};
88
89/*
90 * EROFS inode datalayout (i_format in on-disk inode):
91 * 0 - uncompressed flat inode without tail-packing inline data:
92 * 1 - compressed inode with non-compact indexes:
93 * 2 - uncompressed flat inode with tail-packing inline data:
94 * 3 - compressed inode with compact indexes:
95 * 4 - chunk-based inode with (optional) multi-device support:
96 * 5~7 - reserved
97 */
98enum {
99 EROFS_INODE_FLAT_PLAIN = 0,
100 EROFS_INODE_COMPRESSED_FULL = 1,
101 EROFS_INODE_FLAT_INLINE = 2,
102 EROFS_INODE_COMPRESSED_COMPACT = 3,
103 EROFS_INODE_CHUNK_BASED = 4,
104 EROFS_INODE_DATALAYOUT_MAX
105};
106
107static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
108{
109 return datamode == EROFS_INODE_COMPRESSED_COMPACT ||
110 datamode == EROFS_INODE_COMPRESSED_FULL;
111}
112
113/* bit definitions of inode i_format */
114#define EROFS_I_VERSION_MASK 0x01
115#define EROFS_I_DATALAYOUT_MASK 0x07
116
117#define EROFS_I_VERSION_BIT 0
118#define EROFS_I_DATALAYOUT_BIT 1
119#define EROFS_I_ALL_BIT 4
120
121#define EROFS_I_ALL ((1 << EROFS_I_ALL_BIT) - 1)
122
123/* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */
124#define EROFS_CHUNK_FORMAT_BLKBITS_MASK 0x001F
125/* with chunk indexes or just a 4-byte blkaddr array */
126#define EROFS_CHUNK_FORMAT_INDEXES 0x0020
127
128#define EROFS_CHUNK_FORMAT_ALL \
129 (EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES)
130
131/* 32-byte on-disk inode */
132#define EROFS_INODE_LAYOUT_COMPACT 0
133/* 64-byte on-disk inode */
134#define EROFS_INODE_LAYOUT_EXTENDED 1
135
136struct erofs_inode_chunk_info {
137 __le16 format; /* chunk blkbits, etc. */
138 __le16 reserved;
139};
140
141union erofs_inode_i_u {
142 /* total compressed blocks for compressed inodes */
143 __le32 compressed_blocks;
144
145 /* block address for uncompressed flat inodes */
146 __le32 raw_blkaddr;
147
148 /* for device files, used to indicate old/new device # */
149 __le32 rdev;
150
151 /* for chunk-based files, it contains the summary info */
152 struct erofs_inode_chunk_info c;
153};
154
155/* 32-byte reduced form of an ondisk inode */
156struct erofs_inode_compact {
157 __le16 i_format; /* inode format hints */
158
159/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
160 __le16 i_xattr_icount;
161 __le16 i_mode;
162 __le16 i_nlink;
163 __le32 i_size;
164 __le32 i_reserved;
165 union erofs_inode_i_u i_u;
166
167 __le32 i_ino; /* only used for 32-bit stat compatibility */
168 __le16 i_uid;
169 __le16 i_gid;
170 __le32 i_reserved2;
171};
172
173/* 64-byte complete form of an ondisk inode */
174struct erofs_inode_extended {
175 __le16 i_format; /* inode format hints */
176
177/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
178 __le16 i_xattr_icount;
179 __le16 i_mode;
180 __le16 i_reserved;
181 __le64 i_size;
182 union erofs_inode_i_u i_u;
183
184 __le32 i_ino; /* only used for 32-bit stat compatibility */
185 __le32 i_uid;
186 __le32 i_gid;
187 __le64 i_mtime;
188 __le32 i_mtime_nsec;
189 __le32 i_nlink;
190 __u8 i_reserved2[16];
191};
192
193/*
194 * inline xattrs (n == i_xattr_icount):
195 * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
196 * 12 bytes / \
197 * / \
198 * /-----------------------\
199 * | erofs_xattr_entries+ |
200 * +-----------------------+
201 * inline xattrs must starts in erofs_xattr_ibody_header,
202 * for read-only fs, no need to introduce h_refcount
203 */
204struct erofs_xattr_ibody_header {
205 __le32 h_name_filter; /* bit value 1 indicates not-present */
206 __u8 h_shared_count;
207 __u8 h_reserved2[7];
208 __le32 h_shared_xattrs[]; /* shared xattr id array */
209};
210
211/* Name indexes */
212#define EROFS_XATTR_INDEX_USER 1
213#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2
214#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
215#define EROFS_XATTR_INDEX_TRUSTED 4
216#define EROFS_XATTR_INDEX_LUSTRE 5
217#define EROFS_XATTR_INDEX_SECURITY 6
218
219/*
220 * bit 7 of e_name_index is set when it refers to a long xattr name prefix,
221 * while the remained lower bits represent the index of the prefix.
222 */
223#define EROFS_XATTR_LONG_PREFIX 0x80
224#define EROFS_XATTR_LONG_PREFIX_MASK 0x7f
225
226#define EROFS_XATTR_FILTER_BITS 32
227#define EROFS_XATTR_FILTER_DEFAULT UINT32_MAX
228#define EROFS_XATTR_FILTER_SEED 0x25BBE08F
229
230/* xattr entry (for both inline & shared xattrs) */
231struct erofs_xattr_entry {
232 __u8 e_name_len; /* length of name */
233 __u8 e_name_index; /* attribute name index */
234 __le16 e_value_size; /* size of attribute value */
235 /* followed by e_name and e_value */
236 char e_name[]; /* attribute name */
237};
238
239/* long xattr name prefix */
240struct erofs_xattr_long_prefix {
241 __u8 base_index; /* short xattr name prefix index */
242 char infix[]; /* infix apart from short prefix */
243};
244
245static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
246{
247 if (!i_xattr_icount)
248 return 0;
249
250 return sizeof(struct erofs_xattr_ibody_header) +
251 sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
252}
253
254#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
255
256static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
257{
258 return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
259 e->e_name_len + le16_to_cpu(e->e_value_size));
260}
261
262/* represent a zeroed chunk (hole) */
263#define EROFS_NULL_ADDR -1
264
265/* 4-byte block address array */
266#define EROFS_BLOCK_MAP_ENTRY_SIZE sizeof(__le32)
267
268/* 8-byte inode chunk indexes */
269struct erofs_inode_chunk_index {
270 __le16 advise; /* always 0, don't care for now */
271 __le16 device_id; /* back-end storage id (with bits masked) */
272 __le32 blkaddr; /* start block address of this inode chunk */
273};
274
275/* dirent sorts in alphabet order, thus we can do binary search */
276struct erofs_dirent {
277 __le64 nid; /* node number */
278 __le16 nameoff; /* start offset of file name */
279 __u8 file_type; /* file type */
280 __u8 reserved; /* reserved */
281} __packed;
282
283/*
284 * EROFS file types should match generic FT_* types and
285 * it seems no need to add BUILD_BUG_ONs since potential
286 * unmatchness will break other fses as well...
287 */
288
289#define EROFS_NAME_LEN 255
290
291/* maximum supported encoded size of a physical compressed cluster */
292#define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024)
293
294/* maximum supported decoded size of a physical compressed cluster */
295#define Z_EROFS_PCLUSTER_MAX_DSIZE (12 * 1024 * 1024)
296
297/* available compression algorithm types (for h_algorithmtype) */
298enum {
299 Z_EROFS_COMPRESSION_LZ4 = 0,
300 Z_EROFS_COMPRESSION_LZMA = 1,
301 Z_EROFS_COMPRESSION_DEFLATE = 2,
302 Z_EROFS_COMPRESSION_ZSTD = 3,
303 Z_EROFS_COMPRESSION_MAX
304};
305#define Z_EROFS_ALL_COMPR_ALGS ((1 << Z_EROFS_COMPRESSION_MAX) - 1)
306
307/* 14 bytes (+ length field = 16 bytes) */
308struct z_erofs_lz4_cfgs {
309 __le16 max_distance;
310 __le16 max_pclusterblks;
311 u8 reserved[10];
312} __packed;
313
314/* 14 bytes (+ length field = 16 bytes) */
315struct z_erofs_lzma_cfgs {
316 __le32 dict_size;
317 __le16 format;
318 u8 reserved[8];
319} __packed;
320
321#define Z_EROFS_LZMA_MAX_DICT_SIZE (8 * Z_EROFS_PCLUSTER_MAX_SIZE)
322
323/* 6 bytes (+ length field = 8 bytes) */
324struct z_erofs_deflate_cfgs {
325 u8 windowbits; /* 8..15 for DEFLATE */
326 u8 reserved[5];
327} __packed;
328
329/* 6 bytes (+ length field = 8 bytes) */
330struct z_erofs_zstd_cfgs {
331 u8 format;
332 u8 windowlog; /* windowLog - ZSTD_WINDOWLOG_ABSOLUTEMIN(10) */
333 u8 reserved[4];
334} __packed;
335
336#define Z_EROFS_ZSTD_MAX_DICT_SIZE Z_EROFS_PCLUSTER_MAX_SIZE
337
338/*
339 * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
340 * e.g. for 4k logical cluster size, 4B if compacted 2B is off;
341 * (4B) + 2B + (4B) if compacted 2B is on.
342 * bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
343 * bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
344 * bit 3 : tailpacking inline pcluster (0 - off; 1 - on)
345 * bit 4 : interlaced plain pcluster (0 - off; 1 - on)
346 * bit 5 : fragment pcluster (0 - off; 1 - on)
347 */
348#define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
349#define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
350#define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004
351#define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008
352#define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010
353#define Z_EROFS_ADVISE_FRAGMENT_PCLUSTER 0x0020
354
355#define Z_EROFS_FRAGMENT_INODE_BIT 7
356struct z_erofs_map_header {
357 union {
358 /* fragment data offset in the packed inode */
359 __le32 h_fragmentoff;
360 struct {
361 __le16 h_reserved1;
362 /* indicates the encoded size of tailpacking data */
363 __le16 h_idata_size;
364 };
365 };
366 __le16 h_advise;
367 /*
368 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
369 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
370 */
371 __u8 h_algorithmtype;
372 /*
373 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
374 * bit 3-6 : reserved;
375 * bit 7 : move the whole file into packed inode or not.
376 */
377 __u8 h_clusterbits;
378};
379
380/*
381 * On-disk logical cluster type:
382 * 0 - literal (uncompressed) lcluster
383 * 1,3 - compressed lcluster (for HEAD lclusters)
384 * 2 - compressed lcluster (for NONHEAD lclusters)
385 *
386 * In detail,
387 * 0 - literal (uncompressed) lcluster,
388 * di_advise = 0
389 * di_clusterofs = the literal data offset of the lcluster
390 * di_blkaddr = the blkaddr of the literal pcluster
391 *
392 * 1,3 - compressed lcluster (for HEAD lclusters)
393 * di_advise = 1 or 3
394 * di_clusterofs = the decompressed data offset of the lcluster
395 * di_blkaddr = the blkaddr of the compressed pcluster
396 *
397 * 2 - compressed lcluster (for NONHEAD lclusters)
398 * di_advise = 2
399 * di_clusterofs =
400 * the decompressed data offset in its own HEAD lcluster
401 * di_u.delta[0] = distance to this HEAD lcluster
402 * di_u.delta[1] = distance to the next HEAD lcluster
403 */
404enum {
405 Z_EROFS_LCLUSTER_TYPE_PLAIN = 0,
406 Z_EROFS_LCLUSTER_TYPE_HEAD1 = 1,
407 Z_EROFS_LCLUSTER_TYPE_NONHEAD = 2,
408 Z_EROFS_LCLUSTER_TYPE_HEAD2 = 3,
409 Z_EROFS_LCLUSTER_TYPE_MAX
410};
411
412#define Z_EROFS_LI_LCLUSTER_TYPE_MASK (Z_EROFS_LCLUSTER_TYPE_MAX - 1)
413
414/* (noncompact only, HEAD) This pcluster refers to partial decompressed data */
415#define Z_EROFS_LI_PARTIAL_REF (1 << 15)
416
417/*
418 * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
419 * compressed block count of a compressed extent (in logical clusters, aka.
420 * block count of a pcluster).
421 */
422#define Z_EROFS_LI_D0_CBLKCNT (1 << 11)
423
424struct z_erofs_lcluster_index {
425 __le16 di_advise;
426 /* where to decompress in the head lcluster */
427 __le16 di_clusterofs;
428
429 union {
430 /* for the HEAD lclusters */
431 __le32 blkaddr;
432 /*
433 * for the NONHEAD lclusters
434 * [0] - distance to its HEAD lcluster
435 * [1] - distance to the next HEAD lcluster
436 */
437 __le16 delta[2];
438 } di_u;
439};
440
441#define Z_EROFS_FULL_INDEX_ALIGN(end) \
442 (ALIGN(end, 8) + sizeof(struct z_erofs_map_header) + 8)
443
444/* check the EROFS on-disk layout strictly at compile time */
445static inline void erofs_check_ondisk_layout_definitions(void)
446{
447 const __le64 fmh = *(__le64 *)&(struct z_erofs_map_header) {
448 .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT
449 };
450
451 BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
452 BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
453 BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
454 BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
455 BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
456 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4);
457 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8);
458 BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
459 BUILD_BUG_ON(sizeof(struct z_erofs_lcluster_index) != 8);
460 BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
461 /* keep in sync between 2 index structures for better extendibility */
462 BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) !=
463 sizeof(struct z_erofs_lcluster_index));
464 BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
465
466 /* exclude old compiler versions like gcc 7.5.0 */
467 BUILD_BUG_ON(__builtin_constant_p(fmh) ?
468 fmh != cpu_to_le64(1ULL << 63) : 0);
469}
470
471#endif