2 * This file is part of UBIFS.
4 * Copyright (C) 2006-2008 Nokia Corporation.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 * Authors: Artem Bityutskiy (Битюцкий Артём)
24 * This file describes UBIFS on-flash format and contains definitions of all the
25 * relevant data structures and constants.
27 * All UBIFS on-flash objects are stored in the form of nodes. All nodes start
28 * with the UBIFS node magic number and have the same common header. Nodes
29 * always sit at 8-byte aligned positions on the media and node header sizes are
30 * also 8-byte aligned (except for the indexing node and the padding node).
33 #ifndef __UBIFS_MEDIA_H__
34 #define __UBIFS_MEDIA_H__
36 /* UBIFS node magic number (must not have the padding byte first or last) */
37 #define UBIFS_NODE_MAGIC 0x06101831
40 * UBIFS on-flash format version. This version is increased when the on-flash
41 * format is changing. If this happens, UBIFS is will support older versions as
42 * well. But older UBIFS code will not support newer formats. Format changes
43 * will be rare and only when absolutely necessary, e.g. to fix a bug or to add
46 * UBIFS went into mainline kernel with format version 4. The older formats
47 * were development formats.
49 #define UBIFS_FORMAT_VERSION 4
52 * Read-only compatibility version. If the UBIFS format is changed, older UBIFS
53 * implementations will not be able to mount newer formats in read-write mode.
54 * However, depending on the change, it may be possible to mount newer formats
55 * in R/O mode. This is indicated by the R/O compatibility version which is
56 * stored in the super-block.
58 * This is needed to support boot-loaders which only need R/O mounting. With
59 * this flag it is possible to do UBIFS format changes without a need to update
62 #define UBIFS_RO_COMPAT_VERSION 0
64 /* Minimum logical eraseblock size in bytes */
65 #define UBIFS_MIN_LEB_SZ (15*1024)
67 /* Initial CRC32 value used when calculating CRC checksums */
68 #define UBIFS_CRC32_INIT 0xFFFFFFFFU
71 * UBIFS does not try to compress data if its length is less than the below
74 #define UBIFS_MIN_COMPR_LEN 128
77 * If compressed data length is less than %UBIFS_MIN_COMPRESS_DIFF bytes
78 * shorter than uncompressed data length, UBIFS prefers to leave this data
79 * node uncompress, because it'll be read faster.
81 #define UBIFS_MIN_COMPRESS_DIFF 64
83 /* Root inode number */
84 #define UBIFS_ROOT_INO 1
86 /* Lowest inode number used for regular inodes (not UBIFS-only internal ones) */
87 #define UBIFS_FIRST_INO 64
90 * Maximum file name and extended attribute length (must be a multiple of 8,
93 #define UBIFS_MAX_NLEN 255
95 /* Maximum number of data journal heads */
96 #define UBIFS_MAX_JHEADS 1
99 * Size of UBIFS data block. Note, UBIFS is not a block oriented file-system,
100 * which means that it does not treat the underlying media as consisting of
101 * blocks like in case of hard drives. Do not be confused. UBIFS block is just
102 * the maximum amount of data which one data node can have or which can be
103 * attached to an inode node.
105 #define UBIFS_BLOCK_SIZE 4096
106 #define UBIFS_BLOCK_SHIFT 12
108 /* UBIFS padding byte pattern (must not be first or last byte of node magic) */
109 #define UBIFS_PADDING_BYTE 0xCE
111 /* Maximum possible key length */
112 #define UBIFS_MAX_KEY_LEN 16
114 /* Key length ("simple" format) */
115 #define UBIFS_SK_LEN 8
117 /* Minimum index tree fanout */
118 #define UBIFS_MIN_FANOUT 3
120 /* Maximum number of levels in UBIFS indexing B-tree */
121 #define UBIFS_MAX_LEVELS 512
123 /* Maximum amount of data attached to an inode in bytes */
124 #define UBIFS_MAX_INO_DATA UBIFS_BLOCK_SIZE
126 /* LEB Properties Tree fanout (must be power of 2) and fanout shift */
127 #define UBIFS_LPT_FANOUT 4
128 #define UBIFS_LPT_FANOUT_SHIFT 2
130 /* LEB Properties Tree bit field sizes */
131 #define UBIFS_LPT_CRC_BITS 16
132 #define UBIFS_LPT_CRC_BYTES 2
133 #define UBIFS_LPT_TYPE_BITS 4
135 /* The key is always at the same position in all keyed nodes */
136 #define UBIFS_KEY_OFFSET offsetof(struct ubifs_ino_node, key)
139 * LEB Properties Tree node types.
141 * UBIFS_LPT_PNODE: LPT leaf node (contains LEB properties)
142 * UBIFS_LPT_NNODE: LPT internal node
143 * UBIFS_LPT_LTAB: LPT's own lprops table
144 * UBIFS_LPT_LSAVE: LPT's save table (big model only)
145 * UBIFS_LPT_NODE_CNT: count of LPT node types
146 * UBIFS_LPT_NOT_A_NODE: all ones (15 for 4 bits) is never a valid node type
154 UBIFS_LPT_NOT_A_NODE = (1 << UBIFS_LPT_TYPE_BITS) - 1,
160 * UBIFS_ITYPE_REG: regular file
161 * UBIFS_ITYPE_DIR: directory
162 * UBIFS_ITYPE_LNK: soft link
163 * UBIFS_ITYPE_BLK: block device node
164 * UBIFS_ITYPE_CHR: character device node
165 * UBIFS_ITYPE_FIFO: fifo
166 * UBIFS_ITYPE_SOCK: socket
167 * UBIFS_ITYPES_CNT: count of supported file types
181 * Supported key hash functions.
183 * UBIFS_KEY_HASH_R5: R5 hash
184 * UBIFS_KEY_HASH_TEST: test hash which just returns first 4 bytes of the name
192 * Supported key formats.
194 * UBIFS_SIMPLE_KEY_FMT: simple key format
197 UBIFS_SIMPLE_KEY_FMT,
201 * The simple key format uses 29 bits for storing UBIFS block number and hash
204 #define UBIFS_S_KEY_BLOCK_BITS 29
205 #define UBIFS_S_KEY_BLOCK_MASK 0x1FFFFFFF
206 #define UBIFS_S_KEY_HASH_BITS UBIFS_S_KEY_BLOCK_BITS
207 #define UBIFS_S_KEY_HASH_MASK UBIFS_S_KEY_BLOCK_MASK
212 * UBIFS_INO_KEY: inode node key
213 * UBIFS_DATA_KEY: data node key
214 * UBIFS_DENT_KEY: directory entry node key
215 * UBIFS_XENT_KEY: extended attribute entry key
216 * UBIFS_KEY_TYPES_CNT: number of supported key types
226 /* Count of LEBs reserved for the superblock area */
227 #define UBIFS_SB_LEBS 1
228 /* Count of LEBs reserved for the master area */
229 #define UBIFS_MST_LEBS 2
231 /* First LEB of the superblock area */
232 #define UBIFS_SB_LNUM 0
233 /* First LEB of the master area */
234 #define UBIFS_MST_LNUM (UBIFS_SB_LNUM + UBIFS_SB_LEBS)
235 /* First LEB of the log area */
236 #define UBIFS_LOG_LNUM (UBIFS_MST_LNUM + UBIFS_MST_LEBS)
239 * The below constants define the absolute minimum values for various UBIFS
240 * media areas. Many of them actually depend of flash geometry and the FS
241 * configuration (number of journal heads, orphan LEBs, etc). This means that
242 * the smallest volume size which can be used for UBIFS cannot be pre-defined
243 * by these constants. The file-system that meets the below limitation will not
244 * necessarily mount. UBIFS does run-time calculations and validates the FS
248 /* Minimum number of logical eraseblocks in the log */
249 #define UBIFS_MIN_LOG_LEBS 2
250 /* Minimum number of bud logical eraseblocks (one for each head) */
251 #define UBIFS_MIN_BUD_LEBS 3
252 /* Minimum number of journal logical eraseblocks */
253 #define UBIFS_MIN_JNL_LEBS (UBIFS_MIN_LOG_LEBS + UBIFS_MIN_BUD_LEBS)
254 /* Minimum number of LPT area logical eraseblocks */
255 #define UBIFS_MIN_LPT_LEBS 2
256 /* Minimum number of orphan area logical eraseblocks */
257 #define UBIFS_MIN_ORPH_LEBS 1
259 * Minimum number of main area logical eraseblocks (buds, 3 for the index, 1
260 * for GC, 1 for deletions, and at least 1 for committed data).
262 #define UBIFS_MIN_MAIN_LEBS (UBIFS_MIN_BUD_LEBS + 6)
264 /* Minimum number of logical eraseblocks */
265 #define UBIFS_MIN_LEB_CNT (UBIFS_SB_LEBS + UBIFS_MST_LEBS + \
266 UBIFS_MIN_LOG_LEBS + UBIFS_MIN_LPT_LEBS + \
267 UBIFS_MIN_ORPH_LEBS + UBIFS_MIN_MAIN_LEBS)
269 /* Node sizes (N.B. these are guaranteed to be multiples of 8) */
270 #define UBIFS_CH_SZ sizeof(struct ubifs_ch)
271 #define UBIFS_INO_NODE_SZ sizeof(struct ubifs_ino_node)
272 #define UBIFS_DATA_NODE_SZ sizeof(struct ubifs_data_node)
273 #define UBIFS_DENT_NODE_SZ sizeof(struct ubifs_dent_node)
274 #define UBIFS_TRUN_NODE_SZ sizeof(struct ubifs_trun_node)
275 #define UBIFS_PAD_NODE_SZ sizeof(struct ubifs_pad_node)
276 #define UBIFS_SB_NODE_SZ sizeof(struct ubifs_sb_node)
277 #define UBIFS_MST_NODE_SZ sizeof(struct ubifs_mst_node)
278 #define UBIFS_REF_NODE_SZ sizeof(struct ubifs_ref_node)
279 #define UBIFS_IDX_NODE_SZ sizeof(struct ubifs_idx_node)
280 #define UBIFS_CS_NODE_SZ sizeof(struct ubifs_cs_node)
281 #define UBIFS_ORPH_NODE_SZ sizeof(struct ubifs_orph_node)
282 /* Extended attribute entry nodes are identical to directory entry nodes */
283 #define UBIFS_XENT_NODE_SZ UBIFS_DENT_NODE_SZ
284 /* Only this does not have to be multiple of 8 bytes */
285 #define UBIFS_BRANCH_SZ sizeof(struct ubifs_branch)
287 /* Maximum node sizes (N.B. these are guaranteed to be multiples of 8) */
288 #define UBIFS_MAX_DATA_NODE_SZ (UBIFS_DATA_NODE_SZ + UBIFS_BLOCK_SIZE)
289 #define UBIFS_MAX_INO_NODE_SZ (UBIFS_INO_NODE_SZ + UBIFS_MAX_INO_DATA)
290 #define UBIFS_MAX_DENT_NODE_SZ (UBIFS_DENT_NODE_SZ + UBIFS_MAX_NLEN + 1)
291 #define UBIFS_MAX_XENT_NODE_SZ UBIFS_MAX_DENT_NODE_SZ
293 /* The largest UBIFS node */
294 #define UBIFS_MAX_NODE_SZ UBIFS_MAX_INO_NODE_SZ
297 * On-flash inode flags.
299 * UBIFS_COMPR_FL: use compression for this inode
300 * UBIFS_SYNC_FL: I/O on this inode has to be synchronous
301 * UBIFS_IMMUTABLE_FL: inode is immutable
302 * UBIFS_APPEND_FL: writes to the inode may only append data
303 * UBIFS_DIRSYNC_FL: I/O on this directory inode has to be synchronous
304 * UBIFS_XATTR_FL: this inode is the inode for an extended attribute value
306 * Note, these are on-flash flags which correspond to ioctl flags
307 * (@FS_COMPR_FL, etc). They have the same values now, but generally, do not
308 * have to be the same.
311 UBIFS_COMPR_FL = 0x01,
312 UBIFS_SYNC_FL = 0x02,
313 UBIFS_IMMUTABLE_FL = 0x04,
314 UBIFS_APPEND_FL = 0x08,
315 UBIFS_DIRSYNC_FL = 0x10,
316 UBIFS_XATTR_FL = 0x20,
319 /* Inode flag bits used by UBIFS */
320 #define UBIFS_FL_MASK 0x0000001F
323 * UBIFS compression algorithms.
325 * UBIFS_COMPR_NONE: no compression
326 * UBIFS_COMPR_LZO: LZO compression
327 * UBIFS_COMPR_ZLIB: ZLIB compression
328 * UBIFS_COMPR_TYPES_CNT: count of supported compression types
334 UBIFS_COMPR_TYPES_CNT,
340 * UBIFS_INO_NODE: inode node
341 * UBIFS_DATA_NODE: data node
342 * UBIFS_DENT_NODE: directory entry node
343 * UBIFS_XENT_NODE: extended attribute node
344 * UBIFS_TRUN_NODE: truncation node
345 * UBIFS_PAD_NODE: padding node
346 * UBIFS_SB_NODE: superblock node
347 * UBIFS_MST_NODE: master node
348 * UBIFS_REF_NODE: LEB reference node
349 * UBIFS_IDX_NODE: index node
350 * UBIFS_CS_NODE: commit start node
351 * UBIFS_ORPH_NODE: orphan node
352 * UBIFS_NODE_TYPES_CNT: count of supported node types
354 * Note, we index arrays by these numbers, so keep them low and contiguous.
355 * Node type constants for inodes, direntries and so on have to be the same as
356 * corresponding key type constants.
371 UBIFS_NODE_TYPES_CNT,
377 * UBIFS_MST_DIRTY: rebooted uncleanly - master node is dirty
378 * UBIFS_MST_NO_ORPHS: no orphan inodes present
379 * UBIFS_MST_RCVRY: written by recovery
383 UBIFS_MST_NO_ORPHS = 2,
388 * Node group type (used by recovery to recover whole group or none).
390 * UBIFS_NO_NODE_GROUP: this node is not part of a group
391 * UBIFS_IN_NODE_GROUP: this node is a part of a group
392 * UBIFS_LAST_OF_NODE_GROUP: this node is the last in a group
395 UBIFS_NO_NODE_GROUP = 0,
397 UBIFS_LAST_OF_NODE_GROUP,
403 * UBIFS_FLG_BIGLPT: if "big" LPT model is used if set
406 UBIFS_FLG_BIGLPT = 0x02,
410 * struct ubifs_ch - common header node.
411 * @magic: UBIFS node magic number (%UBIFS_NODE_MAGIC)
412 * @crc: CRC-32 checksum of the node header
413 * @sqnum: sequence number
414 * @len: full node length
415 * @node_type: node type
416 * @group_type: node group type
417 * @padding: reserved for future, zeroes
419 * Every UBIFS node starts with this common part. If the node has a key, the
420 * key always goes next.
430 } __attribute__ ((packed));
433 * union ubifs_dev_desc - device node descriptor.
434 * @new: new type device descriptor
435 * @huge: huge type device descriptor
437 * This data structure describes major/minor numbers of a device node. In an
438 * inode is a device node then its data contains an object of this type. UBIFS
439 * uses standard Linux "new" and "huge" device node encodings.
441 union ubifs_dev_desc {
444 } __attribute__ ((packed));
447 * struct ubifs_ino_node - inode node.
450 * @creat_sqnum: sequence number at time of creation
451 * @size: inode size in bytes (amount of uncompressed data)
452 * @atime_sec: access time seconds
453 * @ctime_sec: creation time seconds
454 * @mtime_sec: modification time seconds
455 * @atime_nsec: access time nanoseconds
456 * @ctime_nsec: creation time nanoseconds
457 * @mtime_nsec: modification time nanoseconds
458 * @nlink: number of hard links
461 * @mode: access flags
462 * @flags: per-inode flags (%UBIFS_COMPR_FL, %UBIFS_SYNC_FL, etc)
463 * @data_len: inode data length
464 * @xattr_cnt: count of extended attributes this inode has
465 * @xattr_size: summarized size of all extended attributes in bytes
466 * @padding1: reserved for future, zeroes
467 * @xattr_names: sum of lengths of all extended attribute names belonging to
469 * @compr_type: compression type used for this inode
470 * @padding2: reserved for future, zeroes
471 * @data: data attached to the inode
473 * Note, even though inode compression type is defined by @compr_type, some
474 * nodes of this inode may be compressed with different compressor - this
475 * happens if compression type is changed while the inode already has data
476 * nodes. But @compr_type will be use for further writes to the inode.
478 * Note, do not forget to amend 'zero_ino_node_unused()' function when changing
479 * the padding fields.
481 struct ubifs_ino_node {
483 __u8 key[UBIFS_MAX_KEY_LEN];
500 __u8 padding1[4]; /* Watch 'zero_ino_node_unused()' if changing! */
503 __u8 padding2[26]; /* Watch 'zero_ino_node_unused()' if changing! */
505 } __attribute__ ((packed));
508 * struct ubifs_dent_node - directory entry node.
511 * @inum: target inode number
512 * @padding1: reserved for future, zeroes
513 * @type: type of the target inode (%UBIFS_ITYPE_REG, %UBIFS_ITYPE_DIR, etc)
515 * @padding2: reserved for future, zeroes
516 * @name: zero-terminated name
518 * Note, do not forget to amend 'zero_dent_node_unused()' function when
519 * changing the padding fields.
521 struct ubifs_dent_node {
523 __u8 key[UBIFS_MAX_KEY_LEN];
528 __u8 padding2[4]; /* Watch 'zero_dent_node_unused()' if changing! */
530 } __attribute__ ((packed));
533 * struct ubifs_data_node - data node.
536 * @size: uncompressed data size in bytes
537 * @compr_type: compression type (%UBIFS_COMPR_NONE, %UBIFS_COMPR_LZO, etc)
538 * @padding: reserved for future, zeroes
541 * Note, do not forget to amend 'zero_data_node_unused()' function when
542 * changing the padding fields.
544 struct ubifs_data_node {
546 __u8 key[UBIFS_MAX_KEY_LEN];
549 __u8 padding[2]; /* Watch 'zero_data_node_unused()' if changing! */
551 } __attribute__ ((packed));
554 * struct ubifs_trun_node - truncation node.
556 * @inum: truncated inode number
557 * @padding: reserved for future, zeroes
558 * @old_size: size before truncation
559 * @new_size: size after truncation
561 * This node exists only in the journal and never goes to the main area. Note,
562 * do not forget to amend 'zero_trun_node_unused()' function when changing the
565 struct ubifs_trun_node {
568 __u8 padding[12]; /* Watch 'zero_trun_node_unused()' if changing! */
571 } __attribute__ ((packed));
574 * struct ubifs_pad_node - padding node.
576 * @pad_len: how many bytes after this node are unused (because padded)
577 * @padding: reserved for future, zeroes
579 struct ubifs_pad_node {
582 } __attribute__ ((packed));
585 * struct ubifs_sb_node - superblock node.
587 * @padding: reserved for future, zeroes
588 * @key_hash: type of hash function used in keys
589 * @key_fmt: format of the key
590 * @flags: file-system flags (%UBIFS_FLG_BIGLPT, etc)
591 * @min_io_size: minimal input/output unit size
592 * @leb_size: logical eraseblock size in bytes
593 * @leb_cnt: count of LEBs used by file-system
594 * @max_leb_cnt: maximum count of LEBs used by file-system
595 * @max_bud_bytes: maximum amount of data stored in buds
596 * @log_lebs: log size in logical eraseblocks
597 * @lpt_lebs: number of LEBs used for lprops table
598 * @orph_lebs: number of LEBs used for recording orphans
599 * @jhead_cnt: count of journal heads
600 * @fanout: tree fanout (max. number of links per indexing node)
601 * @lsave_cnt: number of LEB numbers in LPT's save table
602 * @fmt_version: UBIFS on-flash format version
603 * @default_compr: default compression algorithm (%UBIFS_COMPR_LZO, etc)
604 * @padding1: reserved for future, zeroes
605 * @rp_uid: reserve pool UID
606 * @rp_gid: reserve pool GID
607 * @rp_size: size of the reserved pool in bytes
608 * @padding2: reserved for future, zeroes
609 * @time_gran: time granularity in nanoseconds
610 * @uuid: UUID generated when the file system image was created
611 * @ro_compat_version: UBIFS R/O compatibility version
613 struct ubifs_sb_node {
623 __le64 max_bud_bytes;
631 __le16 default_compr;
638 __le32 ro_compat_version;
640 } __attribute__ ((packed));
643 * struct ubifs_mst_node - master node.
645 * @highest_inum: highest inode number in the committed index
646 * @cmt_no: commit number
647 * @flags: various flags (%UBIFS_MST_DIRTY, etc)
648 * @log_lnum: start of the log
649 * @root_lnum: LEB number of the root indexing node
650 * @root_offs: offset within @root_lnum
651 * @root_len: root indexing node length
652 * @gc_lnum: LEB reserved for garbage collection (%-1 value means the LEB was
653 * not reserved and should be reserved on mount)
654 * @ihead_lnum: LEB number of index head
655 * @ihead_offs: offset of index head
656 * @index_size: size of index on flash
657 * @total_free: total free space in bytes
658 * @total_dirty: total dirty space in bytes
659 * @total_used: total used space in bytes (includes only data LEBs)
660 * @total_dead: total dead space in bytes (includes only data LEBs)
661 * @total_dark: total dark space in bytes (includes only data LEBs)
662 * @lpt_lnum: LEB number of LPT root nnode
663 * @lpt_offs: offset of LPT root nnode
664 * @nhead_lnum: LEB number of LPT head
665 * @nhead_offs: offset of LPT head
666 * @ltab_lnum: LEB number of LPT's own lprops table
667 * @ltab_offs: offset of LPT's own lprops table
668 * @lsave_lnum: LEB number of LPT's save table (big model only)
669 * @lsave_offs: offset of LPT's save table (big model only)
670 * @lscan_lnum: LEB number of last LPT scan
671 * @empty_lebs: number of empty logical eraseblocks
672 * @idx_lebs: number of indexing logical eraseblocks
673 * @leb_cnt: count of LEBs used by file-system
674 * @padding: reserved for future, zeroes
676 struct ubifs_mst_node {
707 } __attribute__ ((packed));
710 * struct ubifs_ref_node - logical eraseblock reference node.
712 * @lnum: the referred logical eraseblock number
713 * @offs: start offset in the referred LEB
714 * @jhead: journal head number
715 * @padding: reserved for future, zeroes
717 struct ubifs_ref_node {
723 } __attribute__ ((packed));
726 * struct ubifs_branch - key/reference/length branch
727 * @lnum: LEB number of the target node
728 * @offs: offset within @lnum
729 * @len: target node length
732 struct ubifs_branch {
737 } __attribute__ ((packed));
740 * struct ubifs_idx_node - indexing node.
742 * @child_cnt: number of child index nodes
744 * @branches: LEB number / offset / length / key branches
746 struct ubifs_idx_node {
751 } __attribute__ ((packed));
754 * struct ubifs_cs_node - commit start node.
756 * @cmt_no: commit number
758 struct ubifs_cs_node {
761 } __attribute__ ((packed));
764 * struct ubifs_orph_node - orphan node.
766 * @cmt_no: commit number (also top bit is set on the last node of the commit)
767 * @inos: inode numbers of orphans
769 struct ubifs_orph_node {
773 } __attribute__ ((packed));
775 #endif /* __UBIFS_MEDIA_H__ */