* Copyright (c) 2008, 2009 Reinoud Zandijk

/* $NetBSD: nilfs_fs.h,v 1.5 2024/12/26 21:16:26 andvar Exp $ */

/*
* Copyright (c) 2008, 2009 Reinoud Zandijk
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* NilFS on disc structures
*
* Original definitions written by Koji Sato <[email protected]>
* and Ryusuke Konishi <[email protected]>
*/

#ifndef _NILFS_FS_H
#define _NILFS_FS_H

/*
* NiLFS stores ext2fs compatible flags in its Inode. NetBSD uses a comparable
* mechanism with file flags to be mutated with chflags(2).
*
* For completion, i mention all ext2-fs flags currently stored in NiLFS
* inodes.
*/
#define NILFS_SECRM_FL 0x00000001 /* no mapping; delete securely */
#define NILFS_UNRM_FL 0x00000002 /* no mapping; allow undelete */
#define NILFS_SYNC_FL 0x00000008 /* no mapping; sychrone update */
#define NILFS_IMMUTABLE_FL 0x00000010 /* SF_IMMUTABLE | UF_IMMUTABLE */
#define NILFS_APPEND_FL 0x00000020 /* SF_APPEND | UF_APPEND */
#define NILFS_NODUMP_FL 0x00000040 /* UF_NODUMP */
#define NILFS_NOATIME_FL 0x00000080 /* no mapping; no atime update */
/* intermediate bits are reserved for compression settings */
#define NILFS_NOTAIL_FL 0x00008000 /* no mapping; dont merge tail */
#define NILFS_DIRSYNC_FL 0x00010000 /* no mapping; dirsync */

#define NILFS_FL_USER_VISIBLE 0x0003DFFF /* flags visible to user */
#define NILFS_FL_USER_MODIFIABLE 0x000380FF /* flags modifiable by user */

/*
* NiLFS stores files in hierarchical B-trees in tupels of (dkey, dptr).
* Entries in a level N btree point to a btree of level N-1. As dkey value the
* first block number to be found in the level N-1 btree is taken.
*
* To conserve disk space and to reduce an extra lookup, small B-tree's of
* level 0 consisting of only the first [0..NILFS_DIRECT_KEY_MAX> entries are
* stored directly into the inode without dkey. Otherwise the entries point to
* the B-tree's of level N-1.
*
* In all B-trees, but of the system DAT-file, the dptr values are virtual
* block numbers. The dptr values in the B-tree of the system DAT-file are
* physical block numbers since the DAT performs virtual to physical block
* mapping.
*/

#define NILFS_INODE_BMAP_SIZE 7

#define NILFS_BMAP_SIZE (NILFS_INODE_BMAP_SIZE * sizeof(uint64_t))
#define NILFS_BMAP_INVALID_PTR 0

#define NILFS_DIRECT_NBLOCKS (NILFS_BMAP_SIZE / sizeof(uint64_t) - 1)
#define NILFS_DIRECT_KEY_MIN 0
#define NILFS_DIRECT_KEY_MAX (NILFS_DIRECT_NBLOCKS - 1)

#define NILFS_BMAP_SMALL_LOW NILFS_DIRECT_KEY_MIN
#define NILFS_BMAP_SMALL_HIGH NILFS_DIRECT_KEY_MAX
#define NILFS_BMAP_LARGE_LOW NILFS_BTREE_ROOT_NCHILDREN_MAX
#define NILFS_BMAP_LARGE_HIGH NILFS_BTREE_KEY_MAX

/*
* B-tree header found on all btree blocks and in the direct-entry. Its size
* should be 64 bits. In a direct entry, it is followed by 64 bits block
* numbers for the translation of block [0..NILFS_DIRECT_KEY_MAX>. In large
* bmaps its followed by pairs of 64 bit dkey and 64 bit dptr.
*/

struct nilfs_btree_node {
uint8_t bn_flags; /* btree flags */
uint8_t bn_level; /* level of btree */
uint16_t bn_nchildren; /* number of children in this record */
uint32_t bn_pad; /* pad to 64 bits */
};

/* btree flags stored in nilfs_btree_node->bn_flags */
#define NILFS_BTREE_NODE_ROOT 0x01
#define NILFS_BMAP_LARGE 0x01 /* equivalent to BTREE_NODE_ROOT */

/* btree levels stored in nilfs_btree_node->bn_level */
#define NILFS_BTREE_LEVEL_DATA 0
#define NILFS_BTREE_LEVEL_NODE_MIN (NILFS_BTREE_LEVEL_DATA + 1)
#define NILFS_BTREE_LEVEL_MAX 14

/*
* Calculate number of entries that fit into the `direct' space
*/
#define NILFS_BTREE_ROOT_SIZE NILFS_BMAP_SIZE
#define NILFS_BTREE_ROOT_NCHILDREN_MAX \
((NILFS_BTREE_ROOT_SIZE - sizeof(struct nilfs_btree_node)) / \
(sizeof(uint64_t /* dkey */) + sizeof(uint64_t /* dptr */)))
#define NILFS_BTREE_ROOT_NCHILDREN_MIN 0

/*
* Calculate number of entries that fit into a non LEVEL_DATA nodes. Each of
* those nodes are padded with one extra 64 bit (extension?)
*/
#define NILFS_BTREE_NODE_EXTRA_PAD_SIZE (sizeof(uint64_t))
#define NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize) \
(((nodesize) - sizeof(struct nilfs_btree_node) - \
NILFS_BTREE_NODE_EXTRA_PAD_SIZE) / \
(sizeof(uint64_t /* dkey */) + sizeof(uint64_t /* dptr */)))
#define NILFS_BTREE_NODE_NCHILDREN_MIN(nodesize) \
((NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize) - 1) / 2 + 1)
#define NILFS_BTREE_KEY_MIN ( (uint64_t) 0)
#define NILFS_BTREE_KEY_MAX (~(uint64_t) 0)

/*
* NiLFS inode structure. There are a few dedicated inode numbers that are
* defined here first.
*/

#define NILFS_ROOT_INO 2 /* Root file inode */
#define NILFS_DAT_INO 3 /* DAT file */
#define NILFS_CPFILE_INO 4 /* checkpoint file */
#define NILFS_SUFILE_INO 5 /* segment usage file */
#define NILFS_IFILE_INO 6 /* ifile */
#define NILFS_ATIME_INO 7 /* Atime file (reserved) */
#define NILFS_XATTR_INO 8 /* Xattribute file (reserved) */
#define NILFS_SKETCH_INO 10 /* Sketch file (obsolete) */
#define NILFS_USER_INO 11 /* First user's file inode number */

struct nilfs_inode {
uint64_t i_blocks; /* size in device blocks */
uint64_t i_size; /* size in bytes */
uint64_t i_ctime; /* creation time in seconds part */
uint64_t i_mtime; /* modification time in seconds part */
uint32_t i_ctime_nsec; /* creation time nanoseconds part */
uint32_t i_mtime_nsec; /* modification time in nanoseconds */
uint32_t i_uid; /* user id */
uint32_t i_gid; /* group id */
uint16_t i_mode; /* file mode */
uint16_t i_links_count; /* number of references to the inode */
uint32_t i_flags; /* NILFS_*_FL flags */
uint64_t i_bmap[NILFS_INODE_BMAP_SIZE]; /* btree direct/large */
#define i_device_code i_bmap[0] /* 64 bits composed of major+minor */
uint64_t i_xattr; /* reserved for extended attributes */
uint32_t i_generation; /* file generation for NFS */
uint32_t i_pad; /* make it 64 bits aligned */
};

/*
* In NiLFS each checkpoint/snapshot has a super root.
*
* The super root holds the inodes of the three system files: `dat', `cp' and
* 'su' files. All other FS state is defined by those.
*
* It is crc checksum'ed and time stamped.
*/

struct nilfs_super_root {
uint32_t sr_sum; /* check-sum */
uint16_t sr_bytes; /* byte count of this structure */
uint16_t sr_flags; /* reserved for flags */
uint64_t sr_nongc_ctime; /* timestamp, not for cleaner(?) */
struct nilfs_inode sr_dat; /* DAT, virt->phys translation inode */
struct nilfs_inode sr_cpfile; /* CP, checkpoints inode */
struct nilfs_inode sr_sufile; /* SU, segment usage inode */
};

#define NILFS_SR_MDT_OFFSET(inode_size, i) \
((uint32_t)&((struct nilfs_super_root *)0)->sr_dat + \
(inode_size) * (i))
#define NILFS_SR_DAT_OFFSET(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 0)
#define NILFS_SR_CPFILE_OFFSET(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 1)
#define NILFS_SR_SUFILE_OFFSET(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 2)
#define NILFS_SR_BYTES (sizeof(struct nilfs_super_root))

/*
* NiLFS has a superblock that describes the basic structure and mount
* history. It also records some sizes of structures found on the disc for
* sanity checks.
*
* The superblock is stored at two places: NILFS_SB_OFFSET_BYTES and
* NILFS_SB2_OFFSET_BYTES.
*/

#define NILFS_DFL_MAX_MNT_COUNT 50 /* default 50 mounts before fsck */
#define NILFS_EIO_RETRY_COUNT 4 /* then give up, not used yet */

/* File system states stored on disc in superblock's sbp->s_state */
#define NILFS_VALID_FS 0x0001 /* cleanly unmounted and all is ok */
#define NILFS_ERROR_FS 0x0002 /* there were errors detected, fsck */
#define NILFS_RESIZE_FS 0x0004 /* resize required, XXX unknown flag*/
#define NILFS_MOUNT_STATE_BITS "\20\1VALID_FS\2ERROR_FS\3RESIZE_FS"

/* Mount option flags passed in Linux; Not used but here for reference */
#define NILFS_MOUNT_ERROR_MODE 0x0070 /* error mode mask */
#define NILFS_MOUNT_ERRORS_CONT 0x0010 /* continue on errors */
#define NILFS_MOUNT_ERRORS_RO 0x0020 /* remount fs ro on errors */
#define NILFS_MOUNT_ERRORS_PANIC 0x0040 /* panic on errors */
#define NILFS_MOUNT_SNAPSHOT 0x0080 /* snapshot flag */
#define NILFS_MOUNT_BARRIER 0x1000 /* use block barriers XXX what is this? */
#define NILFS_MOUNT_STRICT_ORDER 0x2000 /* apply strict in-order; */
/* semantics also for data */

struct nilfs_super_block {
uint32_t s_rev_level; /* major disk format revision */
uint16_t s_minor_rev_level; /* minor disc format revision */
uint16_t s_magic; /* magic value for identification */

uint16_t s_bytes; /* byte count of CRC calculation
for this structure. s_reserved
is excluded! */
uint16_t s_flags; /* linux mount flags, XXX can they
be ignored? */
uint32_t s_crc_seed; /* seed value of CRC calculation */
uint32_t s_sum; /* check sum of super block */

/* Block size represented as follows
blocksize = 1 << (s_log_block_size + 10) */
uint32_t s_log_block_size;
uint64_t s_nsegments; /* number of segm. in filesystem */
uint64_t s_dev_size; /* block device size in bytes */
uint64_t s_first_data_block; /* 1st seg disk block number */
uint32_t s_blocks_per_segment; /* number of blocks per segment */
uint32_t s_r_segments_percentage; /* reserved segments percentage */

uint64_t s_last_cno; /* last checkpoint number */
uint64_t s_last_pseg; /* addr part. segm. written last */
uint64_t s_last_seq; /* seq.number of seg written last */
uint64_t s_free_blocks_count; /* free blocks count */

uint64_t s_ctime; /* creation time (execution time
of newfs) */
uint64_t s_mtime; /* mount time */
uint64_t s_wtime; /* write time */
uint16_t s_mnt_count; /* mount count */
uint16_t s_max_mnt_count; /* maximal mount count */
uint16_t s_state; /* file system state */
uint16_t s_errors; /* behaviour on detecting errors */
uint64_t s_lastcheck; /* time of last checked */

uint32_t s_checkinterval; /* max. time between checks */
uint32_t s_creator_os; /* OS that created it */
uint16_t s_def_resuid; /* default uid for reserv. blocks */
uint16_t s_def_resgid; /* default gid for reserv. blocks */
uint32_t s_first_ino; /* first non-reserved inode */

uint16_t s_inode_size; /* size of an inode */
uint16_t s_dat_entry_size; /* size of a dat entry */
uint16_t s_checkpoint_size; /* size of a checkpoint */
uint16_t s_segment_usage_size; /* size of a segment usage */

uint8_t s_uuid[16]; /* 128-bit uuid for volume */
char s_volume_name[80]; /* volume name */

uint32_t s_c_interval; /* commit interval of segment */
uint32_t s_c_block_max; /* threshold of data amount for
the segment construction */
uint32_t s_reserved[192]; /* padding to end of the block */
};

#define NILFS_SUPER_MAGIC 0x3434 /* NILFS filesystem magic number */
#define NILFS_SB_OFFSET_BYTES 1024 /* byte offset of nilfs superblock */
#define NILFS_SB2_OFFSET_BYTES(devsize) ((((devsize) >> 12) - 1) << 12)

/* codes for operating systems in superblock */
#define NILFS_OS_LINUX 0
#define NILFS_OS_UNK1 1 /* ext2 */
#define NILFS_OS_UNK2 2 /* ext2 */
#define NILFS_OS_UNK3 3 /* ext2 */
#define NILFS_OS_NETBSD 10 /* temp */

/* NiLFS revision levels */
#define NILFS_CURRENT_REV 2 /* current major revision */
#define NILFS_MINOR_REV 0 /* minor revision */

/* Bytes count of super_block for CRC-calculation */
#define NILFS_SB_BYTES \
((uint32_t)&((struct nilfs_super_block *)0)->s_reserved)

/* Maximal count of links to a file */
#define NILFS_LINK_MAX 32000

/*
* Structure of a directory entry, same as ext2.
*
* The `file_type' is chosen there since filenames are limited to 256 bytes
* and the name_len in ext2 is a two byter.
*
* Note that they can't span blocks; the rec_len fills out.
*/

#define NILFS_NAME_LEN 255
struct nilfs_dir_entry {
uint64_t inode; /* inode number */
uint16_t rec_len; /* directory entry length */
uint8_t name_len; /* name length */
uint8_t file_type;
char name[NILFS_NAME_LEN]; /* file name */
char pad;
};

/*
* NILFS directory file types. Only the low 3 bits are used. The
* other bits are reserved for now.
*/
enum {
NILFS_FT_UNKNOWN,
NILFS_FT_REG_FILE,
NILFS_FT_DIR,
NILFS_FT_CHRDEV,
NILFS_FT_BLKDEV,
NILFS_FT_FIFO,
NILFS_FT_SOCK,
NILFS_FT_SYMLINK,
NILFS_FT_MAX
};

/*
* NILFS_DIR_PAD defines the directory entries boundaries
*
* NOTE: It must be a multiple of 8
*/
#define NILFS_DIR_PAD 8
#define NILFS_DIR_ROUND (NILFS_DIR_PAD - 1)
#define NILFS_DIR_REC_LEN(name_len) (((name_len) + 12 + NILFS_DIR_ROUND) & \
~NILFS_DIR_ROUND)

/*
* NiLFS devides the disc into fixed length segments. Each segment is filled
* with one or more partial segments of variable lengths.
*
* Each partial segment has a segment summary header followed by updates of
* files and optionally a super root.
*/

struct nilfs_finfo {
uint64_t fi_ino; /* inode number */
uint64_t fi_cno; /* checkpoint associated with this */
uint32_t fi_nblocks; /* size in blocks of this finfo */
uint32_t fi_ndatablk; /* number of data blocks */
/* For the DAT file */
/* fi_ndatablk * nilfs_binfo.bi_dat.bi_blkoff */
/* fi_nblocks - fi_ndatablks * nilfs_binfo.bi_dat */
/* Other files */
/* fi_ndatablk * nilfs_binfo.bi_v */
/* fi_nblocks - fi_ndatablks * nilfs_binfo.bi_v.bi_vblocknr */
};

/*
* Virtual to physical block translation information. For data blocks it maps
* logical block number bi_blkoff to virtual block nr bi_vblocknr. For non
* datablocks it is the virtual block number assigned to an inserted btree
* level and thus has no bi_blkoff. The physical block number is the next
* available data block in the partial segment after all the finfo's.
*/
struct nilfs_binfo_v {
uint64_t bi_vblocknr; /* assigned virtual block number */
uint64_t bi_blkoff; /* for file's logical block number */
};

/*
* DAT allocation. For data blocks just the logical block number that maps on
* the next available data block in the partial segment after the finfo's.
* Intermediate btree blocks are looked up by their blkoffset dkey and their
* level and given the next available data block.
*/
struct nilfs_binfo_dat {
uint64_t bi_blkoff; /* DAT file's logical block number */
uint8_t bi_level; /* btree level */
uint8_t bi_pad[7];
};

/* Convenience union for both types of binfo's */
union nilfs_binfo {
struct nilfs_binfo_v bi_v;
struct nilfs_binfo_dat bi_dat;
};

/* The (partial) segment summary itself */
struct nilfs_segment_summary {
uint32_t ss_datasum; /* CRC of complete data block */
uint32_t ss_sumsum; /* CRC of segment summary only */
uint32_t ss_magic; /* magic to identify segment summary */
uint16_t ss_bytes; /* size of segment summary structure */
uint16_t ss_flags; /* NILFS_SS_* flags */
uint64_t ss_seq; /* sequence number of this segm. sum */
uint64_t ss_create; /* creation timestamp in seconds */
uint64_t ss_next; /* blocknumber of next segment */
uint32_t ss_nblocks; /* number of blocks follow */
uint32_t ss_nfinfo; /* number of finfo structures follow */
uint32_t ss_sumbytes; /* total size of segment summary */
uint32_t ss_pad;
uint64_t ss_cno; /* latest checkpoint number known */
/* stream of finfo structures */
};

#define NILFS_SEGSUM_MAGIC 0x1eaffa11 /* segment summary magic number */

/* Segment summary flags */
#define NILFS_SS_LOGBGN 0x0001 /* begins a logical segment */
#define NILFS_SS_LOGEND 0x0002 /* ends a logical segment */
#define NILFS_SS_SR 0x0004 /* has super root */
#define NILFS_SS_SYNDT 0x0008 /* includes data only updates */
#define NILFS_SS_GC 0x0010 /* segment written for cleaner operation */
#define NILFS_SS_FLAG_BITS "\20\1LOGBGN\2LOGEND\3SR\4SYNDT\5GC"

/* Segment summary constraints */
#define NILFS_SEG_MIN_BLOCKS 16 /* minimum number of blocks in a
full segment */
#define NILFS_PSEG_MIN_BLOCKS 2 /* minimum number of blocks in a
partial segment */
#define NILFS_MIN_NRSVSEGS 8 /* minimum number of reserved
segments */

/*
* Structure of DAT/inode file.
*
* A DAT file is divided into groups. The maximum number of groups is the
* number of block group descriptors that fit into one block; this descriptor
* only gives the number of free entries in the associated group.
*
* Each group has a block sized bitmap indicating if an entry is taken or
* empty. Each bit stands for a DAT entry.
*
* The inode file has exactly the same format only the entries are inode
* entries.
*/

struct nilfs_block_group_desc {
uint32_t bg_nfrees; /* num. free entries in block group */
};

/* DAT entry in a super root's DAT file */
struct nilfs_dat_entry {
uint64_t de_blocknr; /* block number */
uint64_t de_start; /* valid from checkpoint */
uint64_t de_end; /* valid till checkpoint */
uint64_t de_rsv; /* reserved for future use */
};

/*
* Structure of CP file.
*
* A snapshot is just a checkpoint only its protected against removal by the
* cleaner. The snapshots are kept on a double linked list of checkpoints.
*/

struct nilfs_snapshot_list {
uint64_t ssl_next; /* checkpoint nr. forward */
uint64_t ssl_prev; /* checkpoint nr. back */
};

/* checkpoint entry structure */
struct nilfs_checkpoint {
uint32_t cp_flags; /* NILFS_CHECKPOINT_* flags */
uint32_t cp_checkpoints_count; /* ZERO, not used anymore? */
struct nilfs_snapshot_list cp_snapshot_list; /* list of snapshots */
uint64_t cp_cno; /* checkpoint number */
uint64_t cp_create; /* creation timestamp */
uint64_t cp_nblk_inc; /* number of blocks incremented */
uint64_t cp_inodes_count; /* number of inodes in this cp. */
uint64_t cp_blocks_count; /* reserved (might be deleted) */
struct nilfs_inode cp_ifile_inode; /* inode file inode */
};

/* checkpoint flags */
#define NILFS_CHECKPOINT_SNAPSHOT 1
#define NILFS_CHECKPOINT_INVALID 2
#define NILFS_CHECKPOINT_SKETCH 4
#define NILFS_CHECKPOINT_MINOR 8
#define NILFS_CHECKPOINT_BITS "\20\1SNAPSHOT\2INVALID\3SKETCH\4MINOR"

/* header of the checkpoint file */
struct nilfs_cpfile_header {
uint64_t ch_ncheckpoints; /* number of checkpoints */
uint64_t ch_nsnapshots; /* number of snapshots */
struct nilfs_snapshot_list ch_snapshot_list; /* snapshot list */
};

/* to accommodate with the header */
#define NILFS_CPFILE_FIRST_CHECKPOINT_OFFSET \
((sizeof(struct nilfs_cpfile_header) + \
sizeof(struct nilfs_checkpoint) - 1) / \
sizeof(struct nilfs_checkpoint))

/*
* Structure of SU file.
*
* The segment usage file sums up how each of the segments are used. They are
* indexed by their segment number.
*/

/* segment usage entry */
struct nilfs_segment_usage {
uint64_t su_lastmod; /* last modified timestamp */
uint32_t su_nblocks; /* number of blocks in segment */
uint32_t su_flags; /* NILFS_SEGMENT_USAGE_* flags */
};

/* segment usage flag */
#define NILFS_SEGMENT_USAGE_ACTIVE 1
#define NILFS_SEGMENT_USAGE_DIRTY 2
#define NILFS_SEGMENT_USAGE_ERROR 4
#define NILFS_SEGMENT_USAGE_BITS "\20\1ACTIVE\2DIRTY\3ERROR"

/* header of the segment usage file */
struct nilfs_sufile_header {
uint64_t sh_ncleansegs; /* number of segments marked clean */
uint64_t sh_ndirtysegs; /* number of segments marked dirty */
uint64_t sh_last_alloc; /* last allocated segment number */
/* ... */
};

/* to accommodate with the header */
#define NILFS_SUFILE_FIRST_SEGMENT_USAGE_OFFSET \
((sizeof(struct nilfs_sufile_header) + \
sizeof(struct nilfs_segment_usage) - 1) / \
sizeof(struct nilfs_segment_usage))

#endif