nilfs2: move ioctl interface and disk layout to uapi separately

The header file "include/linux/nilfs2_fs.h" is composed of parts for
ioctl and disk format, and both are intended to be shared with user
space programs.

This moves them to the uapi directory "include/uapi/linux" splitting the
file to "nilfs2_api.h" and "nilfs2_ondisk.h".  The following minor
changes are accompanied by this migration:

 - nilfs_direct_node struct in nilfs2/direct.h is converged to
   nilfs2_ondisk.h because it's an on-disk structure.
 - inline functions nilfs_rec_len_from_disk() and
   nilfs_rec_len_to_disk() are moved to nilfs2/dir.c.

Link: http://lkml.kernel.org/r/1465825507-3407-4-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 650 insertions, 0 deletions

diff --git a/include/uapi/linux/nilfs2_ondisk.h b/include/uapi/linux/nilfs2_ondisk.h
new file mode 100644
index 000000000000..2a8a3addb675
--- /dev/null
+++ b/include/uapi/linux/nilfs2_ondisk.h
@@ -0,0 +1,650 @@
+/*
+ * nilfs2_ondisk.h - NILFS2 on-disk structures
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ */
+/*
+ *  linux/include/linux/ext2_fs.h
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/include/linux/minix_fs.h
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#ifndef _LINUX_NILFS2_ONDISK_H
+#define _LINUX_NILFS2_ONDISK_H
+
+#include <linux/types.h>
+#include <linux/magic.h>
+
+
+#define NILFS_INODE_BMAP_SIZE	7
+
+/**
+ * struct nilfs_inode - structure of an inode on disk
+ * @i_blocks: blocks count
+ * @i_size: size in bytes
+ * @i_ctime: creation time (seconds)
+ * @i_mtime: modification time (seconds)
+ * @i_ctime_nsec: creation time (nano seconds)
+ * @i_mtime_nsec: modification time (nano seconds)
+ * @i_uid: user id
+ * @i_gid: group id
+ * @i_mode: file mode
+ * @i_links_count: links count
+ * @i_flags: file flags
+ * @i_bmap: block mapping
+ * @i_xattr: extended attributes
+ * @i_generation: file generation (for NFS)
+ * @i_pad: padding
+ */
+struct nilfs_inode {
+	__le64	i_blocks;
+	__le64	i_size;
+	__le64	i_ctime;
+	__le64	i_mtime;
+	__le32	i_ctime_nsec;
+	__le32	i_mtime_nsec;
+	__le32	i_uid;
+	__le32	i_gid;
+	__le16	i_mode;
+	__le16	i_links_count;
+	__le32	i_flags;
+	__le64	i_bmap[NILFS_INODE_BMAP_SIZE];
+#define i_device_code	i_bmap[0]
+	__le64	i_xattr;
+	__le32	i_generation;
+	__le32	i_pad;
+};
+
+#define NILFS_MIN_INODE_SIZE		128
+
+/**
+ * struct nilfs_super_root - structure of super root
+ * @sr_sum: check sum
+ * @sr_bytes: byte count of the structure
+ * @sr_flags: flags (reserved)
+ * @sr_nongc_ctime: write time of the last segment not for cleaner operation
+ * @sr_dat: DAT file inode
+ * @sr_cpfile: checkpoint file inode
+ * @sr_sufile: segment usage file inode
+ */
+struct nilfs_super_root {
+	__le32 sr_sum;
+	__le16 sr_bytes;
+	__le16 sr_flags;
+	__le64 sr_nongc_ctime;
+	struct nilfs_inode sr_dat;
+	struct nilfs_inode sr_cpfile;
+	struct nilfs_inode sr_sufile;
+};
+
+#define NILFS_SR_MDT_OFFSET(inode_size, i)  \
+	((unsigned long)&((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(inode_size)	    NILFS_SR_MDT_OFFSET(inode_size, 3)
+
+/*
+ * Maximal mount counts
+ */
+#define NILFS_DFL_MAX_MNT_COUNT		50      /* 50 mounts */
+
+/*
+ * File system states (sbp->s_state, nilfs->ns_mount_state)
+ */
+#define NILFS_VALID_FS			0x0001  /* Unmounted cleanly */
+#define NILFS_ERROR_FS			0x0002  /* Errors detected */
+#define NILFS_RESIZE_FS			0x0004	/* Resize required */
+
+/*
+ * Mount flags (sbi->s_mount_opt)
+ */
+#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_BARRIER		0x1000  /* Use block barriers */
+#define NILFS_MOUNT_STRICT_ORDER	0x2000  /*
+						 * Apply strict in-order
+						 * semantics also for data
+						 */
+#define NILFS_MOUNT_NORECOVERY		0x4000  /*
+						 * Disable write access during
+						 * mount-time recovery
+						 */
+#define NILFS_MOUNT_DISCARD		0x8000  /* Issue DISCARD requests */
+
+
+/**
+ * struct nilfs_super_block - structure of super block on disk
+ */
+struct nilfs_super_block {
+/*00*/	__le32	s_rev_level;		/* Revision level */
+	__le16	s_minor_rev_level;	/* minor revision level */
+	__le16	s_magic;		/* Magic signature */
+
+	__le16  s_bytes;		/*
+					 * Bytes count of CRC calculation
+					 * for this structure. s_reserved
+					 * is excluded.
+					 */
+	__le16  s_flags;		/* flags */
+	__le32  s_crc_seed;		/* Seed value of CRC calculation */
+/*10*/	__le32	s_sum;			/* Check sum of super block */
+
+	__le32	s_log_block_size;	/*
+					 * Block size represented as follows
+					 * blocksize =
+					 *     1 << (s_log_block_size + 10)
+					 */
+	__le64  s_nsegments;		/* Number of segments in filesystem */
+/*20*/	__le64  s_dev_size;		/* block device size in bytes */
+	__le64	s_first_data_block;	/* 1st seg disk block number */
+/*30*/	__le32  s_blocks_per_segment;   /* number of blocks per full segment */
+	__le32	s_r_segments_percentage; /* Reserved segments percentage */
+
+	__le64  s_last_cno;		/* Last checkpoint number */
+/*40*/	__le64  s_last_pseg;		/* disk block addr pseg written last */
+	__le64  s_last_seq;             /* seq. number of seg written last */
+/*50*/	__le64	s_free_blocks_count;	/* Free blocks count */
+
+	__le64	s_ctime;		/*
+					 * Creation time (execution time of
+					 * newfs)
+					 */
+/*60*/	__le64	s_mtime;		/* Mount time */
+	__le64	s_wtime;		/* Write time */
+/*70*/	__le16	s_mnt_count;		/* Mount count */
+	__le16	s_max_mnt_count;	/* Maximal mount count */
+	__le16	s_state;		/* File system state */
+	__le16	s_errors;		/* Behaviour when detecting errors */
+	__le64	s_lastcheck;		/* time of last check */
+
+/*80*/	__le32	s_checkinterval;	/* max. time between checks */
+	__le32	s_creator_os;		/* OS */
+	__le16	s_def_resuid;		/* Default uid for reserved blocks */
+	__le16	s_def_resgid;		/* Default gid for reserved blocks */
+	__le32	s_first_ino;		/* First non-reserved inode */
+
+/*90*/	__le16  s_inode_size;		/* Size of an inode */
+	__le16  s_dat_entry_size;       /* Size of a dat entry */
+	__le16  s_checkpoint_size;      /* Size of a checkpoint */
+	__le16	s_segment_usage_size;	/* Size of a segment usage */
+
+/*98*/	__u8	s_uuid[16];		/* 128-bit uuid for volume */
+/*A8*/	char	s_volume_name[80];	/* volume name */
+
+/*F8*/	__le32  s_c_interval;           /* Commit interval of segment */
+	__le32  s_c_block_max;          /*
+					 * Threshold of data amount for
+					 * the segment construction
+					 */
+/*100*/	__le64  s_feature_compat;	/* Compatible feature set */
+	__le64  s_feature_compat_ro;	/* Read-only compatible feature set */
+	__le64  s_feature_incompat;	/* Incompatible feature set */
+	__u32	s_reserved[186];	/* padding to the end of the block */
+};
+
+/*
+ * Codes for operating systems
+ */
+#define NILFS_OS_LINUX		0
+/* Codes from 1 to 4 are reserved to keep compatibility with ext2 creator-OS */
+
+/*
+ * Revision levels
+ */
+#define NILFS_CURRENT_REV	2	/* current major revision */
+#define NILFS_MINOR_REV		0	/* minor revision */
+#define NILFS_MIN_SUPP_REV	2	/* minimum supported revision */
+
+/*
+ * Feature set definitions
+ *
+ * If there is a bit set in the incompatible feature set that the kernel
+ * doesn't know about, it should refuse to mount the filesystem.
+ */
+#define NILFS_FEATURE_COMPAT_RO_BLOCK_COUNT	0x00000001ULL
+
+#define NILFS_FEATURE_COMPAT_SUPP	0ULL
+#define NILFS_FEATURE_COMPAT_RO_SUPP	NILFS_FEATURE_COMPAT_RO_BLOCK_COUNT
+#define NILFS_FEATURE_INCOMPAT_SUPP	0ULL
+
+/*
+ * Bytes count of super_block for CRC-calculation
+ */
+#define NILFS_SB_BYTES  \
+	((long)&((struct nilfs_super_block *)0)->s_reserved)
+
+/*
+ * Special inode number
+ */
+#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 */
+#define NILFS_USER_INO		11	/* Fisrt user's file inode number */
+
+#define NILFS_SB_OFFSET_BYTES	1024	/* byte offset of nilfs superblock */
+
+#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
+					 */
+
+/*
+ * We call DAT, cpfile, and sufile root metadata files.  Inodes of
+ * these files are written in super root block instead of ifile, and
+ * garbage collector doesn't keep any past versions of these files.
+ */
+#define NILFS_ROOT_METADATA_FILE(ino) \
+	((ino) >= NILFS_DAT_INO && (ino) <= NILFS_SUFILE_INO)
+
+/*
+ * bytes offset of secondary super block
+ */
+#define NILFS_SB2_OFFSET_BYTES(devsize)	((((devsize) >> 12) - 1) << 12)
+
+/*
+ * Maximal count of links to a file
+ */
+#define NILFS_LINK_MAX		32000
+
+/*
+ * Structure of a directory entry
+ *  (Same as ext2)
+ */
+
+#define NILFS_NAME_LEN 255
+
+/*
+ * Block size limitations
+ */
+#define NILFS_MIN_BLOCK_SIZE		1024
+#define NILFS_MAX_BLOCK_SIZE		65536
+
+/*
+ * The new version of the directory entry.  Since V0 structures are
+ * stored in intel byte order, and the name_len field could never be
+ * bigger than 255 chars, it's safe to reclaim the extra byte for the
+ * file_type field.
+ */
+struct nilfs_dir_entry {
+	__le64	inode;			/* Inode number */
+	__le16	rec_len;		/* Directory entry length */
+	__u8	name_len;		/* Name length */
+	__u8	file_type;		/* Dir entry type (file, dir, etc) */
+	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)
+#define NILFS_MAX_REC_LEN		((1 << 16) - 1)
+
+/**
+ * struct nilfs_finfo - file information
+ * @fi_ino: inode number
+ * @fi_cno: checkpoint number
+ * @fi_nblocks: number of blocks (including intermediate blocks)
+ * @fi_ndatablk: number of file data blocks
+ */
+struct nilfs_finfo {
+	__le64 fi_ino;
+	__le64 fi_cno;
+	__le32 fi_nblocks;
+	__le32 fi_ndatablk;
+};
+
+/**
+ * struct nilfs_binfo_v - information on a data block (except DAT)
+ * @bi_vblocknr: virtual block number
+ * @bi_blkoff: block offset
+ */
+struct nilfs_binfo_v {
+	__le64 bi_vblocknr;
+	__le64 bi_blkoff;
+};
+
+/**
+ * struct nilfs_binfo_dat - information on a DAT node block
+ * @bi_blkoff: block offset
+ * @bi_level: level
+ * @bi_pad: padding
+ */
+struct nilfs_binfo_dat {
+	__le64 bi_blkoff;
+	__u8 bi_level;
+	__u8 bi_pad[7];
+};
+
+/**
+ * union nilfs_binfo: block information
+ * @bi_v: nilfs_binfo_v structure
+ * @bi_dat: nilfs_binfo_dat structure
+ */
+union nilfs_binfo {
+	struct nilfs_binfo_v bi_v;
+	struct nilfs_binfo_dat bi_dat;
+};
+
+/**
+ * struct nilfs_segment_summary - segment summary header
+ * @ss_datasum: checksum of data
+ * @ss_sumsum: checksum of segment summary
+ * @ss_magic: magic number
+ * @ss_bytes: size of this structure in bytes
+ * @ss_flags: flags
+ * @ss_seq: sequence number
+ * @ss_create: creation timestamp
+ * @ss_next: next segment
+ * @ss_nblocks: number of blocks
+ * @ss_nfinfo: number of finfo structures
+ * @ss_sumbytes: total size of segment summary in bytes
+ * @ss_pad: padding
+ * @ss_cno: checkpoint number
+ */
+struct nilfs_segment_summary {
+	__le32 ss_datasum;
+	__le32 ss_sumsum;
+	__le32 ss_magic;
+	__le16 ss_bytes;
+	__le16 ss_flags;
+	__le64 ss_seq;
+	__le64 ss_create;
+	__le64 ss_next;
+	__le32 ss_nblocks;
+	__le32 ss_nfinfo;
+	__le32 ss_sumbytes;
+	__le32 ss_pad;
+	__le64 ss_cno;
+	/* array 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 */
+
+/**
+ * struct nilfs_btree_node - header of B-tree node block
+ * @bn_flags: flags
+ * @bn_level: level
+ * @bn_nchildren: number of children
+ * @bn_pad: padding
+ */
+struct nilfs_btree_node {
+	__u8 bn_flags;
+	__u8 bn_level;
+	__le16 bn_nchildren;
+	__le32 bn_pad;
+};
+
+/* flags */
+#define NILFS_BTREE_NODE_ROOT   0x01
+
+/* level */
+#define NILFS_BTREE_LEVEL_DATA          0
+#define NILFS_BTREE_LEVEL_NODE_MIN      (NILFS_BTREE_LEVEL_DATA + 1)
+#define NILFS_BTREE_LEVEL_MAX           14	/* Max level (exclusive) */
+
+/**
+ * struct nilfs_direct_node - header of built-in bmap array
+ * @dn_flags: flags
+ * @dn_pad: padding
+ */
+struct nilfs_direct_node {
+	__u8 dn_flags;
+	__u8 pad[7];
+};
+
+/**
+ * struct nilfs_palloc_group_desc - block group descriptor
+ * @pg_nfrees: number of free entries in block group
+ */
+struct nilfs_palloc_group_desc {
+	__le32 pg_nfrees;
+};
+
+/**
+ * struct nilfs_dat_entry - disk address translation entry
+ * @de_blocknr: block number
+ * @de_start: start checkpoint number
+ * @de_end: end checkpoint number
+ * @de_rsv: reserved for future use
+ */
+struct nilfs_dat_entry {
+	__le64 de_blocknr;
+	__le64 de_start;
+	__le64 de_end;
+	__le64 de_rsv;
+};
+
+#define NILFS_MIN_DAT_ENTRY_SIZE	32
+
+/**
+ * struct nilfs_snapshot_list - snapshot list
+ * @ssl_next: next checkpoint number on snapshot list
+ * @ssl_prev: previous checkpoint number on snapshot list
+ */
+struct nilfs_snapshot_list {
+	__le64 ssl_next;
+	__le64 ssl_prev;
+};
+
+/**
+ * struct nilfs_checkpoint - checkpoint structure
+ * @cp_flags: flags
+ * @cp_checkpoints_count: checkpoints count in a block
+ * @cp_snapshot_list: snapshot list
+ * @cp_cno: checkpoint number
+ * @cp_create: creation timestamp
+ * @cp_nblk_inc: number of blocks incremented by this checkpoint
+ * @cp_inodes_count: inodes count
+ * @cp_blocks_count: blocks count
+ * @cp_ifile_inode: inode of ifile
+ */
+struct nilfs_checkpoint {
+	__le32 cp_flags;
+	__le32 cp_checkpoints_count;
+	struct nilfs_snapshot_list cp_snapshot_list;
+	__le64 cp_cno;
+	__le64 cp_create;
+	__le64 cp_nblk_inc;
+	__le64 cp_inodes_count;
+	__le64 cp_blocks_count;
+
+	/*
+	 * Do not change the byte offset of ifile inode.
+	 * To keep the compatibility of the disk format,
+	 * additional fields should be added behind cp_ifile_inode.
+	 */
+	struct nilfs_inode cp_ifile_inode;
+};
+
+#define NILFS_MIN_CHECKPOINT_SIZE	(64 + NILFS_MIN_INODE_SIZE)
+
+/* checkpoint flags */
+enum {
+	NILFS_CHECKPOINT_SNAPSHOT,
+	NILFS_CHECKPOINT_INVALID,
+	NILFS_CHECKPOINT_SKETCH,
+	NILFS_CHECKPOINT_MINOR,
+};
+
+#define NILFS_CHECKPOINT_FNS(flag, name)				\
+static inline void							\
+nilfs_checkpoint_set_##name(struct nilfs_checkpoint *cp)		\
+{									\
+	cp->cp_flags = cpu_to_le32(le32_to_cpu(cp->cp_flags) |		\
+				   (1UL << NILFS_CHECKPOINT_##flag));	\
+}									\
+static inline void							\
+nilfs_checkpoint_clear_##name(struct nilfs_checkpoint *cp)		\
+{									\
+	cp->cp_flags = cpu_to_le32(le32_to_cpu(cp->cp_flags) &		\
+				   ~(1UL << NILFS_CHECKPOINT_##flag));	\
+}									\
+static inline int							\
+nilfs_checkpoint_##name(const struct nilfs_checkpoint *cp)		\
+{									\
+	return !!(le32_to_cpu(cp->cp_flags) &				\
+		  (1UL << NILFS_CHECKPOINT_##flag));			\
+}
+
+NILFS_CHECKPOINT_FNS(SNAPSHOT, snapshot)
+NILFS_CHECKPOINT_FNS(INVALID, invalid)
+NILFS_CHECKPOINT_FNS(MINOR, minor)
+
+/**
+ * struct nilfs_cpfile_header - checkpoint file header
+ * @ch_ncheckpoints: number of checkpoints
+ * @ch_nsnapshots: number of snapshots
+ * @ch_snapshot_list: snapshot list
+ */
+struct nilfs_cpfile_header {
+	__le64 ch_ncheckpoints;
+	__le64 ch_nsnapshots;
+	struct nilfs_snapshot_list ch_snapshot_list;
+};
+
+#define NILFS_CPFILE_FIRST_CHECKPOINT_OFFSET				\
+	((sizeof(struct nilfs_cpfile_header) +				\
+	  sizeof(struct nilfs_checkpoint) - 1) /			\
+			sizeof(struct nilfs_checkpoint))
+
+/**
+ * struct nilfs_segment_usage - segment usage
+ * @su_lastmod: last modified timestamp
+ * @su_nblocks: number of blocks in segment
+ * @su_flags: flags
+ */
+struct nilfs_segment_usage {
+	__le64 su_lastmod;
+	__le32 su_nblocks;
+	__le32 su_flags;
+};
+
+#define NILFS_MIN_SEGMENT_USAGE_SIZE	16
+
+/* segment usage flag */
+enum {
+	NILFS_SEGMENT_USAGE_ACTIVE,
+	NILFS_SEGMENT_USAGE_DIRTY,
+	NILFS_SEGMENT_USAGE_ERROR,
+};
+
+#define NILFS_SEGMENT_USAGE_FNS(flag, name)				\
+static inline void							\
+nilfs_segment_usage_set_##name(struct nilfs_segment_usage *su)		\
+{									\
+	su->su_flags = cpu_to_le32(le32_to_cpu(su->su_flags) |		\
+				   (1UL << NILFS_SEGMENT_USAGE_##flag));\
+}									\
+static inline void							\
+nilfs_segment_usage_clear_##name(struct nilfs_segment_usage *su)	\
+{									\
+	su->su_flags =							\
+		cpu_to_le32(le32_to_cpu(su->su_flags) &			\
+			    ~(1UL << NILFS_SEGMENT_USAGE_##flag));      \
+}									\
+static inline int							\
+nilfs_segment_usage_##name(const struct nilfs_segment_usage *su)	\
+{									\
+	return !!(le32_to_cpu(su->su_flags) &				\
+		  (1UL << NILFS_SEGMENT_USAGE_##flag));			\
+}
+
+NILFS_SEGMENT_USAGE_FNS(ACTIVE, active)
+NILFS_SEGMENT_USAGE_FNS(DIRTY, dirty)
+NILFS_SEGMENT_USAGE_FNS(ERROR, error)
+
+static inline void
+nilfs_segment_usage_set_clean(struct nilfs_segment_usage *su)
+{
+	su->su_lastmod = cpu_to_le64(0);
+	su->su_nblocks = cpu_to_le32(0);
+	su->su_flags = cpu_to_le32(0);
+}
+
+static inline int
+nilfs_segment_usage_clean(const struct nilfs_segment_usage *su)
+{
+	return !le32_to_cpu(su->su_flags);
+}
+
+/**
+ * struct nilfs_sufile_header - segment usage file header
+ * @sh_ncleansegs: number of clean segments
+ * @sh_ndirtysegs: number of dirty segments
+ * @sh_last_alloc: last allocated segment number
+ */
+struct nilfs_sufile_header {
+	__le64 sh_ncleansegs;
+	__le64 sh_ndirtysegs;
+	__le64 sh_last_alloc;
+	/* ... */
+};
+
+#define NILFS_SUFILE_FIRST_SEGMENT_USAGE_OFFSET				\
+	((sizeof(struct nilfs_sufile_header) +				\
+	  sizeof(struct nilfs_segment_usage) - 1) /			\
+			 sizeof(struct nilfs_segment_usage))
+
+#endif	/* _LINUX_NILFS2_ONDISK_H */