ubifs-media.h

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/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file describes UBIFS on-flash format and contains definitions of all the
 * relevant data structures and constants.
 *
 * All UBIFS on-flash objects are stored in the form of nodes. All nodes start
 * with the UBIFS node magic number and have the same common header. Nodes
 * always sit at 8-byte aligned positions on the media and node header sizes are
 * also 8-byte aligned (except for the indexing node and the padding node).
 */

#ifndef __UBIFS_MEDIA_H__
#define __UBIFS_MEDIA_H__

/* UBIFS node magic number (must not have the padding byte first or last) */
#define UBIFS_NODE_MAGIC  0x06101831

/*
 * UBIFS on-flash format version. This version is increased when the on-flash
 * format is changing. If this happens, UBIFS is will support older versions as
 * well. But older UBIFS code will not support newer formats. Format changes
 * will be rare and only when absolutely necessary, e.g. to fix a bug or to add
 * a new feature.
 *
 * UBIFS went into mainline kernel with format version 4. The older formats
 * were development formats.
 */
#define UBIFS_FORMAT_VERSION 4

/*
 * Read-only compatibility version. If the UBIFS format is changed, older UBIFS
 * implementations will not be able to mount newer formats in read-write mode.
 * However, depending on the change, it may be possible to mount newer formats
 * in R/O mode. This is indicated by the R/O compatibility version which is
 * stored in the super-block.
 *
 * This is needed to support boot-loaders which only need R/O mounting. With
 * this flag it is possible to do UBIFS format changes without a need to update
 * boot-loaders.
 */
#define UBIFS_RO_COMPAT_VERSION 0

/* Minimum logical eraseblock size in bytes */
#define UBIFS_MIN_LEB_SZ (15*1024)

/* Initial CRC32 value used when calculating CRC checksums */
#define UBIFS_CRC32_INIT 0xFFFFFFFFU

/*
 * UBIFS does not try to compress data if its length is less than the below
 * constant.
 */
#define UBIFS_MIN_COMPR_LEN 128

/*
 * If compressed data length is less than %UBIFS_MIN_COMPRESS_DIFF bytes
 * shorter than uncompressed data length, UBIFS prefers to leave this data
 * node uncompress, because it'll be read faster.
 */
#define UBIFS_MIN_COMPRESS_DIFF 64

/* Root inode number */
#define UBIFS_ROOT_INO 1

/* Lowest inode number used for regular inodes (not UBIFS-only internal ones) */
#define UBIFS_FIRST_INO 64

/*
 * Maximum file name and extended attribute length (must be a multiple of 8,
 * minus 1).
 */
#define UBIFS_MAX_NLEN 255

/* Maximum number of data journal heads */
#define UBIFS_MAX_JHEADS 1

/*
 * Size of UBIFS data block. Note, UBIFS is not a block oriented file-system,
 * which means that it does not treat the underlying media as consisting of
 * blocks like in case of hard drives. Do not be confused. UBIFS block is just
 * the maximum amount of data which one data node can have or which can be
 * attached to an inode node.
 */
#define UBIFS_BLOCK_SIZE  4096
#define UBIFS_BLOCK_SHIFT 12

/* UBIFS padding byte pattern (must not be first or last byte of node magic) */
#define UBIFS_PADDING_BYTE 0xCE

/* Maximum possible key length */
#define UBIFS_MAX_KEY_LEN 16

/* Key length ("simple" format) */
#define UBIFS_SK_LEN 8

/* Minimum index tree fanout */
#define UBIFS_MIN_FANOUT 3

/* Maximum number of levels in UBIFS indexing B-tree */
#define UBIFS_MAX_LEVELS 512

/* Maximum amount of data attached to an inode in bytes */
#define UBIFS_MAX_INO_DATA UBIFS_BLOCK_SIZE

/* LEB Properties Tree fanout (must be power of 2) and fanout shift */
#define UBIFS_LPT_FANOUT 4
#define UBIFS_LPT_FANOUT_SHIFT 2

/* LEB Properties Tree bit field sizes */
#define UBIFS_LPT_CRC_BITS 16
#define UBIFS_LPT_CRC_BYTES 2
#define UBIFS_LPT_TYPE_BITS 4

/* The key is always at the same position in all keyed nodes */
#define UBIFS_KEY_OFFSET offsetof(struct ubifs_ino_node, key)

/* Garbage collector journal head number */
#define UBIFS_GC_HEAD   0
/* Base journal head number */
#define UBIFS_BASE_HEAD 1
/* Data journal head number */
#define UBIFS_DATA_HEAD 2

/*
 * LEB Properties Tree node types.
 *
 * UBIFS_LPT_PNODE: LPT leaf node (contains LEB properties)
 * UBIFS_LPT_NNODE: LPT internal node
 * UBIFS_LPT_LTAB: LPT's own lprops table
 * UBIFS_LPT_LSAVE: LPT's save table (big model only)
 * UBIFS_LPT_NODE_CNT: count of LPT node types
 * UBIFS_LPT_NOT_A_NODE: all ones (15 for 4 bits) is never a valid node type
 */
enum {
    UBIFS_LPT_PNODE,
    UBIFS_LPT_NNODE,
    UBIFS_LPT_LTAB,
    UBIFS_LPT_LSAVE,
    UBIFS_LPT_NODE_CNT,
    UBIFS_LPT_NOT_A_NODE = (1 << UBIFS_LPT_TYPE_BITS) - 1,
};

/*
 * UBIFS inode types.
 *
 * UBIFS_ITYPE_REG: regular file
 * UBIFS_ITYPE_DIR: directory
 * UBIFS_ITYPE_LNK: soft link
 * UBIFS_ITYPE_BLK: block device node
 * UBIFS_ITYPE_CHR: character device node
 * UBIFS_ITYPE_FIFO: fifo
 * UBIFS_ITYPE_SOCK: socket
 * UBIFS_ITYPES_CNT: count of supported file types
 */
enum {
    UBIFS_ITYPE_REG,
    UBIFS_ITYPE_DIR,
    UBIFS_ITYPE_LNK,
    UBIFS_ITYPE_BLK,
    UBIFS_ITYPE_CHR,
    UBIFS_ITYPE_FIFO,
    UBIFS_ITYPE_SOCK,
    UBIFS_ITYPES_CNT,
};

/*
 * Supported key hash functions.
 *
 * UBIFS_KEY_HASH_R5: R5 hash
 * UBIFS_KEY_HASH_TEST: test hash which just returns first 4 bytes of the name
 */
enum {
    UBIFS_KEY_HASH_R5,
    UBIFS_KEY_HASH_TEST,
};

/*
 * Supported key formats.
 *
 * UBIFS_SIMPLE_KEY_FMT: simple key format
 */
enum {
    UBIFS_SIMPLE_KEY_FMT,
};

/*
 * The simple key format uses 29 bits for storing UBIFS block number and hash
 * value.
 */
#define UBIFS_S_KEY_BLOCK_BITS 29
#define UBIFS_S_KEY_BLOCK_MASK 0x1FFFFFFF
#define UBIFS_S_KEY_HASH_BITS  UBIFS_S_KEY_BLOCK_BITS
#define UBIFS_S_KEY_HASH_MASK  UBIFS_S_KEY_BLOCK_MASK

/*
 * Key types.
 *
 * UBIFS_INO_KEY: inode node key
 * UBIFS_DATA_KEY: data node key
 * UBIFS_DENT_KEY: directory entry node key
 * UBIFS_XENT_KEY: extended attribute entry key
 * UBIFS_KEY_TYPES_CNT: number of supported key types
 */
enum {
    UBIFS_INO_KEY,
    UBIFS_DATA_KEY,
    UBIFS_DENT_KEY,
    UBIFS_XENT_KEY,
    UBIFS_KEY_TYPES_CNT,
};

/* Count of LEBs reserved for the superblock area */
#define UBIFS_SB_LEBS 1
/* Count of LEBs reserved for the master area */
#define UBIFS_MST_LEBS 2

/* First LEB of the superblock area */
#define UBIFS_SB_LNUM 0
/* First LEB of the master area */
#define UBIFS_MST_LNUM (UBIFS_SB_LNUM + UBIFS_SB_LEBS)
/* First LEB of the log area */
#define UBIFS_LOG_LNUM (UBIFS_MST_LNUM + UBIFS_MST_LEBS)

/*
 * The below constants define the absolute minimum values for various UBIFS
 * media areas. Many of them actually depend of flash geometry and the FS
 * configuration (number of journal heads, orphan LEBs, etc). This means that
 * the smallest volume size which can be used for UBIFS cannot be pre-defined
 * by these constants. The file-system that meets the below limitation will not
 * necessarily mount. UBIFS does run-time calculations and validates the FS
 * size.
 */

/* Minimum number of logical eraseblocks in the log */
#define UBIFS_MIN_LOG_LEBS 2
/* Minimum number of bud logical eraseblocks (one for each head) */
#define UBIFS_MIN_BUD_LEBS 3
/* Minimum number of journal logical eraseblocks */
#define UBIFS_MIN_JNL_LEBS (UBIFS_MIN_LOG_LEBS + UBIFS_MIN_BUD_LEBS)
/* Minimum number of LPT area logical eraseblocks */
#define UBIFS_MIN_LPT_LEBS 2
/* Minimum number of orphan area logical eraseblocks */
#define UBIFS_MIN_ORPH_LEBS 1
/*
 * Minimum number of main area logical eraseblocks (buds, 3 for the index, 1
 * for GC, 1 for deletions, and at least 1 for committed data).
 */
#define UBIFS_MIN_MAIN_LEBS (UBIFS_MIN_BUD_LEBS + 6)

/* Minimum number of logical eraseblocks */
#define UBIFS_MIN_LEB_CNT (UBIFS_SB_LEBS + UBIFS_MST_LEBS + \
               UBIFS_MIN_LOG_LEBS + UBIFS_MIN_LPT_LEBS + \
               UBIFS_MIN_ORPH_LEBS + UBIFS_MIN_MAIN_LEBS)

/* Node sizes (N.B. these are guaranteed to be multiples of 8) */
#define UBIFS_CH_SZ        sizeof(struct ubifs_ch)
#define UBIFS_INO_NODE_SZ  sizeof(struct ubifs_ino_node)
#define UBIFS_DATA_NODE_SZ sizeof(struct ubifs_data_node)
#define UBIFS_DENT_NODE_SZ sizeof(struct ubifs_dent_node)
#define UBIFS_TRUN_NODE_SZ sizeof(struct ubifs_trun_node)
#define UBIFS_PAD_NODE_SZ  sizeof(struct ubifs_pad_node)
#define UBIFS_SB_NODE_SZ   sizeof(struct ubifs_sb_node)
#define UBIFS_MST_NODE_SZ  sizeof(struct ubifs_mst_node)
#define UBIFS_REF_NODE_SZ  sizeof(struct ubifs_ref_node)
#define UBIFS_IDX_NODE_SZ  sizeof(struct ubifs_idx_node)
#define UBIFS_CS_NODE_SZ   sizeof(struct ubifs_cs_node)
#define UBIFS_ORPH_NODE_SZ sizeof(struct ubifs_orph_node)
/* Extended attribute entry nodes are identical to directory entry nodes */
#define UBIFS_XENT_NODE_SZ UBIFS_DENT_NODE_SZ
/* Only this does not have to be multiple of 8 bytes */
#define UBIFS_BRANCH_SZ    sizeof(struct ubifs_branch)

/* Maximum node sizes (N.B. these are guaranteed to be multiples of 8) */
#define UBIFS_MAX_DATA_NODE_SZ  (UBIFS_DATA_NODE_SZ + UBIFS_BLOCK_SIZE)
#define UBIFS_MAX_INO_NODE_SZ   (UBIFS_INO_NODE_SZ + UBIFS_MAX_INO_DATA)
#define UBIFS_MAX_DENT_NODE_SZ  (UBIFS_DENT_NODE_SZ + UBIFS_MAX_NLEN + 1)
#define UBIFS_MAX_XENT_NODE_SZ  UBIFS_MAX_DENT_NODE_SZ

/* The largest UBIFS node */
#define UBIFS_MAX_NODE_SZ UBIFS_MAX_INO_NODE_SZ

/*
 * On-flash inode flags.
 *
 * UBIFS_COMPR_FL: use compression for this inode
 * UBIFS_SYNC_FL:  I/O on this inode has to be synchronous
 * UBIFS_IMMUTABLE_FL: inode is immutable
 * UBIFS_APPEND_FL: writes to the inode may only append data
 * UBIFS_DIRSYNC_FL: I/O on this directory inode has to be synchronous
 * UBIFS_XATTR_FL: this inode is the inode for an extended attribute value
 *
 * Note, these are on-flash flags which correspond to ioctl flags
 * (@FS_COMPR_FL, etc). They have the same values now, but generally, do not
 * have to be the same.
 */
enum {
    UBIFS_COMPR_FL     = 0x01,
    UBIFS_SYNC_FL      = 0x02,
    UBIFS_IMMUTABLE_FL = 0x04,
    UBIFS_APPEND_FL    = 0x08,
    UBIFS_DIRSYNC_FL   = 0x10,
    UBIFS_XATTR_FL     = 0x20,
};

/* Inode flag bits used by UBIFS */
#define UBIFS_FL_MASK 0x0000001F

/*
 * UBIFS compression algorithms.
 *
 * UBIFS_COMPR_NONE: no compression
 * UBIFS_COMPR_LZO: LZO compression
 * UBIFS_COMPR_ZLIB: ZLIB compression
 * UBIFS_COMPR_TYPES_CNT: count of supported compression types
 */
enum {
    UBIFS_COMPR_NONE,
    UBIFS_COMPR_LZO,
    UBIFS_COMPR_ZLIB,
    UBIFS_COMPR_TYPES_CNT,
};

/*
 * UBIFS node types.
 *
 * UBIFS_INO_NODE: inode node
 * UBIFS_DATA_NODE: data node
 * UBIFS_DENT_NODE: directory entry node
 * UBIFS_XENT_NODE: extended attribute node
 * UBIFS_TRUN_NODE: truncation node
 * UBIFS_PAD_NODE: padding node
 * UBIFS_SB_NODE: superblock node
 * UBIFS_MST_NODE: master node
 * UBIFS_REF_NODE: LEB reference node
 * UBIFS_IDX_NODE: index node
 * UBIFS_CS_NODE: commit start node
 * UBIFS_ORPH_NODE: orphan node
 * UBIFS_NODE_TYPES_CNT: count of supported node types
 *
 * Note, we index arrays by these numbers, so keep them low and contiguous.
 * Node type constants for inodes, direntries and so on have to be the same as
 * corresponding key type constants.
 */
enum {
    UBIFS_INO_NODE,
    UBIFS_DATA_NODE,
    UBIFS_DENT_NODE,
    UBIFS_XENT_NODE,
    UBIFS_TRUN_NODE,
    UBIFS_PAD_NODE,
    UBIFS_SB_NODE,
    UBIFS_MST_NODE,
    UBIFS_REF_NODE,
    UBIFS_IDX_NODE,
    UBIFS_CS_NODE,
    UBIFS_ORPH_NODE,
    UBIFS_NODE_TYPES_CNT,
};

/*
 * Master node flags.
 *
 * UBIFS_MST_DIRTY: rebooted uncleanly - master node is dirty
 * UBIFS_MST_NO_ORPHS: no orphan inodes present
 * UBIFS_MST_RCVRY: written by recovery
 */
enum {
    UBIFS_MST_DIRTY = 1,
    UBIFS_MST_NO_ORPHS = 2,
    UBIFS_MST_RCVRY = 4,
};

/*
 * Node group type (used by recovery to recover whole group or none).
 *
 * UBIFS_NO_NODE_GROUP: this node is not part of a group
 * UBIFS_IN_NODE_GROUP: this node is a part of a group
 * UBIFS_LAST_OF_NODE_GROUP: this node is the last in a group
 */
enum {
    UBIFS_NO_NODE_GROUP = 0,
    UBIFS_IN_NODE_GROUP,
    UBIFS_LAST_OF_NODE_GROUP,
};

/*
 * Superblock flags.
 *
 * UBIFS_FLG_BIGLPT: if "big" LPT model is used if set
 * UBIFS_FLG_SPACE_FIXUP: first-mount "fixup" of free space within LEBs needed
 */
enum {
    UBIFS_FLG_BIGLPT = 0x02,
    UBIFS_FLG_SPACE_FIXUP = 0x04,
};

struct ubifs_ch {
    __le32 magic;
    __le32 crc;
    __le64 sqnum;
    __le32 len;
    __u8 node_type;
    __u8 group_type;
    __u8 padding[2];
} __packed;

union ubifs_dev_desc {
    __le32 new;
    __le64 huge;
} __packed;

struct ubifs_ino_node {
    struct ubifs_ch ch;
    __u8 key[UBIFS_MAX_KEY_LEN];
    __le64 creat_sqnum;
    __le64 size;
    __le64 atime_sec;
    __le64 ctime_sec;
    __le64 mtime_sec;
    __le32 atime_nsec;
    __le32 ctime_nsec;
    __le32 mtime_nsec;
    __le32 nlink;
    __le32 uid;
    __le32 gid;
    __le32 mode;
    __le32 flags;
    __le32 data_len;
    __le32 xattr_cnt;
    __le32 xattr_size;
    __u8 padding1[4]; /* Watch 'zero_ino_node_unused()' if changing! */
    __le32 xattr_names;
    __le16 compr_type;
    __u8 padding2[26]; /* Watch 'zero_ino_node_unused()' if changing! */
    __u8 data[];
} __packed;

struct ubifs_dent_node {
    struct ubifs_ch ch;
    __u8 key[UBIFS_MAX_KEY_LEN];
    __le64 inum;
    __u8 padding1;
    __u8 type;
    __le16 nlen;
    __u8 padding2[4]; /* Watch 'zero_dent_node_unused()' if changing! */
    __u8 name[];
} __packed;

struct ubifs_data_node {
    struct ubifs_ch ch;
    __u8 key[UBIFS_MAX_KEY_LEN];
    __le32 size;
    __le16 compr_type;
    __u8 padding[2]; /* Watch 'zero_data_node_unused()' if changing! */
    __u8 data[];
} __packed;

struct ubifs_trun_node {
    struct ubifs_ch ch;
    __le32 inum;
    __u8 padding[12]; /* Watch 'zero_trun_node_unused()' if changing! */
    __le64 old_size;
    __le64 new_size;
} __packed;

struct ubifs_pad_node {
    struct ubifs_ch ch;
    __le32 pad_len;
} __packed;

struct ubifs_sb_node {
    struct ubifs_ch ch;
    __u8 padding[2];
    __u8 key_hash;
    __u8 key_fmt;
    __le32 flags;
    __le32 min_io_size;
    __le32 leb_size;
    __le32 leb_cnt;
    __le32 max_leb_cnt;
    __le64 max_bud_bytes;
    __le32 log_lebs;
    __le32 lpt_lebs;
    __le32 orph_lebs;
    __le32 jhead_cnt;
    __le32 fanout;
    __le32 lsave_cnt;
    __le32 fmt_version;
    __le16 default_compr;
    __u8 padding1[2];
    __le32 rp_uid;
    __le32 rp_gid;
    __le64 rp_size;
    __le32 time_gran;
    __u8 uuid[16];
    __le32 ro_compat_version;
    __u8 padding2[3968];
} __packed;

struct ubifs_mst_node {
    struct ubifs_ch ch;
    __le64 highest_inum;
    __le64 cmt_no;
    __le32 flags;
    __le32 log_lnum;
    __le32 root_lnum;
    __le32 root_offs;
    __le32 root_len;
    __le32 gc_lnum;
    __le32 ihead_lnum;
    __le32 ihead_offs;
    __le64 index_size;
    __le64 total_free;
    __le64 total_dirty;
    __le64 total_used;
    __le64 total_dead;
    __le64 total_dark;
    __le32 lpt_lnum;
    __le32 lpt_offs;
    __le32 nhead_lnum;
    __le32 nhead_offs;
    __le32 ltab_lnum;
    __le32 ltab_offs;
    __le32 lsave_lnum;
    __le32 lsave_offs;
    __le32 lscan_lnum;
    __le32 empty_lebs;
    __le32 idx_lebs;
    __le32 leb_cnt;
    __u8 padding[344];
} __packed;

struct ubifs_ref_node {
    struct ubifs_ch ch;
    __le32 lnum;
    __le32 offs;
    __le32 jhead;
    __u8 padding[28];
} __packed;

struct ubifs_branch {
    __le32 lnum;
    __le32 offs;
    __le32 len;
    __u8 key[];
} __packed;

struct ubifs_idx_node {
    struct ubifs_ch ch;
    __le16 child_cnt;
    __le16 level;
    __u8 branches[];
} __packed;

struct ubifs_cs_node {
    struct ubifs_ch ch;
    __le64 cmt_no;
} __packed;

struct ubifs_orph_node {
    struct ubifs_ch ch;
    __le64 cmt_no;
    __le64 inos[];
} __packed;

#endif /* __UBIFS_MEDIA_H__ */