path: root/include/linux/f2fs_fs.h

// SPDX-License-Identifier: GPL-2.0
/**
 * include/linux/f2fs_fs.h
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 */
#ifndef _LINUX_F2FS_FS_H
#define _LINUX_F2FS_FS_H

#include <linux/pagemap.h>
#include <linux/types.h>

#define F2FS_SUPER_OFFSET		1024	/* byte-size offset */
#define F2FS_MIN_LOG_SECTOR_SIZE	9	/* 9 bits for 512 bytes */
#define F2FS_MAX_LOG_SECTOR_SIZE	PAGE_SHIFT	/* Max is Block Size */
#define F2FS_LOG_SECTORS_PER_BLOCK	(PAGE_SHIFT - 9) /* log number for sector/blk */
#define F2FS_BLKSIZE			PAGE_SIZE /* support only block == page */
#define F2FS_BLKSIZE_BITS		PAGE_SHIFT /* bits for F2FS_BLKSIZE */
#define F2FS_MAX_EXTENSION		64	/* # of extension entries */
#define F2FS_EXTENSION_LEN		8	/* max size of extension */
#define F2FS_BLK_ALIGN(x)	(((x) + F2FS_BLKSIZE - 1) >> F2FS_BLKSIZE_BITS)

#define NULL_ADDR		((block_t)0)	/* used as block_t addresses */
#define NEW_ADDR		((block_t)-1)	/* used as block_t addresses */
#define COMPRESS_ADDR		((block_t)-2)	/* used as compressed data flag */

#define F2FS_BYTES_TO_BLK(bytes)	((bytes) >> F2FS_BLKSIZE_BITS)
#define F2FS_BLK_TO_BYTES(blk)		((blk) << F2FS_BLKSIZE_BITS)

/* 0, 1(node nid), 2(meta nid) are reserved node id */
#define F2FS_RESERVED_NODE_NUM		3

#define F2FS_ROOT_INO(sbi)	((sbi)->root_ino_num)
#define F2FS_NODE_INO(sbi)	((sbi)->node_ino_num)
#define F2FS_META_INO(sbi)	((sbi)->meta_ino_num)
#define F2FS_COMPRESS_INO(sbi)	(NM_I(sbi)->max_nid)

#define F2FS_MAX_QUOTAS		3

#define F2FS_ENC_UTF8_12_1	1

/* This flag is used by node and meta inodes, and by recovery */
#define GFP_F2FS_ZERO		(GFP_NOFS | __GFP_ZERO)

/*
 * For further optimization on multi-head logs, on-disk layout supports maximum
 * 16 logs by default. The number, 16, is expected to cover all the cases
 * enoughly. The implementaion currently uses no more than 6 logs.
 * Half the logs are used for nodes, and the other half are used for data.
 */
#define MAX_ACTIVE_LOGS	16
#define MAX_ACTIVE_NODE_LOGS	8
#define MAX_ACTIVE_DATA_LOGS	8

#define VERSION_LEN	256
#define MAX_VOLUME_NAME		512
#define MAX_PATH_LEN		64
#define MAX_DEVICES		8

/*
 * For superblock
 */
struct f2fs_device {
	__u8 path[MAX_PATH_LEN];
	__le32 total_segments;
} __packed;

/* reason of stop_checkpoint */
enum stop_cp_reason {
	STOP_CP_REASON_SHUTDOWN,
	STOP_CP_REASON_FAULT_INJECT,
	STOP_CP_REASON_META_PAGE,
	STOP_CP_REASON_WRITE_FAIL,
	STOP_CP_REASON_CORRUPTED_SUMMARY,
	STOP_CP_REASON_UPDATE_INODE,
	STOP_CP_REASON_FLUSH_FAIL,
	STOP_CP_REASON_NO_SEGMENT,
	STOP_CP_REASON_MAX,
};

#define	MAX_STOP_REASON			32

/* detail reason for EFSCORRUPTED */
enum f2fs_error {
	ERROR_CORRUPTED_CLUSTER,
	ERROR_FAIL_DECOMPRESSION,
	ERROR_INVALID_BLKADDR,
	ERROR_CORRUPTED_DIRENT,
	ERROR_CORRUPTED_INODE,
	ERROR_INCONSISTENT_SUMMARY,
	ERROR_INCONSISTENT_FOOTER,
	ERROR_INCONSISTENT_SUM_TYPE,
	ERROR_CORRUPTED_JOURNAL,
	ERROR_INCONSISTENT_NODE_COUNT,
	ERROR_INCONSISTENT_BLOCK_COUNT,
	ERROR_INVALID_CURSEG,
	ERROR_INCONSISTENT_SIT,
	ERROR_CORRUPTED_VERITY_XATTR,
	ERROR_CORRUPTED_XATTR,
	ERROR_INVALID_NODE_REFERENCE,
	ERROR_INCONSISTENT_NAT,
	ERROR_MAX,
};

#define MAX_F2FS_ERRORS			16

struct f2fs_super_block {
	__le32 magic;			/* Magic Number */
	__le16 major_ver;		/* Major Version */
	__le16 minor_ver;		/* Minor Version */
	__le32 log_sectorsize;		/* log2 sector size in bytes */
	__le32 log_sectors_per_block;	/* log2 # of sectors per block */
	__le32 log_blocksize;		/* log2 block size in bytes */
	__le32 log_blocks_per_seg;	/* log2 # of blocks per segment */
	__le32 segs_per_sec;		/* # of segments per section */
	__le32 secs_per_zone;		/* # of sections per zone */
	__le32 checksum_offset;		/* checksum offset inside super block */
	__le64 block_count;		/* total # of user blocks */
	__le32 section_count;		/* total # of sections */
	__le32 segment_count;		/* total # of segments */
	__le32 segment_count_ckpt;	/* # of segments for checkpoint */
	__le32 segment_count_sit;	/* # of segments for SIT */
	__le32 segment_count_nat;	/* # of segments for NAT */
	__le32 segment_count_ssa;	/* # of segments for SSA */
	__le32 segment_count_main;	/* # of segments for main area */
	__le32 segment0_blkaddr;	/* start block address of segment 0 */
	__le32 cp_blkaddr;		/* start block address of checkpoint */
	__le32 sit_blkaddr;		/* start block address of SIT */
	__le32 nat_blkaddr;		/* start block address of NAT */
	__le32 ssa_blkaddr;		/* start block address of SSA */
	__le32 main_blkaddr;		/* start block address of main area */
	__le32 root_ino;		/* root inode number */
	__le32 node_ino;		/* node inode number */
	__le32 meta_ino;		/* meta inode number */
	__u8 uuid[16];			/* 128-bit uuid for volume */
	__le16 volume_name[MAX_VOLUME_NAME];	/* volume name */
	__le32 extension_count;		/* # of extensions below */
	__u8 extension_list[F2FS_MAX_EXTENSION][F2FS_EXTENSION_LEN];/* extension array */
	__le32 cp_payload;
	__u8 version[VERSION_LEN];	/* the kernel version */
	__u8 init_version[VERSION_LEN];	/* the initial kernel version */
	__le32 feature;			/* defined features */
	__u8 encryption_level;		/* versioning level for encryption */
	__u8 encrypt_pw_salt[16];	/* Salt used for string2key algorithm */
	struct f2fs_device devs[MAX_DEVICES];	/* device list */
	__le32 qf_ino[F2FS_MAX_QUOTAS];	/* quota inode numbers */
	__u8 hot_ext_count;		/* # of hot file extension */
	__le16  s_encoding;		/* Filename charset encoding */
	__le16  s_encoding_flags;	/* Filename charset encoding flags */
	__u8 s_stop_reason[MAX_STOP_REASON];	/* stop checkpoint reason */
	__u8 s_errors[MAX_F2FS_ERRORS];		/* reason of image corrupts */
	__u8 reserved[258];		/* valid reserved region */
	__le32 crc;			/* checksum of superblock */
} __packed;

/*
 * For checkpoint
 */
#define CP_RESIZEFS_FLAG		0x00004000
#define CP_DISABLED_QUICK_FLAG		0x00002000
#define CP_DISABLED_FLAG		0x00001000
#define CP_QUOTA_NEED_FSCK_FLAG		0x00000800
#define CP_LARGE_NAT_BITMAP_FLAG	0x00000400
#define CP_NOCRC_RECOVERY_FLAG	0x00000200
#define CP_TRIMMED_FLAG		0x00000100
#define CP_NAT_BITS_FLAG	0x00000080
#define CP_CRC_RECOVERY_FLAG	0x00000040
#define CP_FASTBOOT_FLAG	0x00000020
#define CP_FSCK_FLAG		0x00000010
#define CP_ERROR_FLAG		0x00000008
#define CP_COMPACT_SUM_FLAG	0x00000004
#define CP_ORPHAN_PRESENT_FLAG	0x00000002
#define CP_UMOUNT_FLAG		0x00000001

#define F2FS_CP_PACKS		2	/* # of checkpoint packs */

struct f2fs_checkpoint {
	__le64 checkpoint_ver;		/* checkpoint block version number */
	__le64 user_block_count;	/* # of user blocks */
	__le64 valid_block_count;	/* # of valid blocks in main area */
	__le32 rsvd_segment_count;	/* # of reserved segments for gc */
	__le32 overprov_segment_count;	/* # of overprovision segments */
	__le32 free_segment_count;	/* # of free segments in main area */

	/* information of current node segments */
	__le32 cur_node_segno[MAX_ACTIVE_NODE_LOGS];
	__le16 cur_node_blkoff[MAX_ACTIVE_NODE_LOGS];
	/* information of current data segments */
	__le32 cur_data_segno[MAX_ACTIVE_DATA_LOGS];
	__le16 cur_data_blkoff[MAX_ACTIVE_DATA_LOGS];
	__le32 ckpt_flags;		/* Flags : umount and journal_present */
	__le32 cp_pack_total_block_count;	/* total # of one cp pack */
	__le32 cp_pack_start_sum;	/* start block number of data summary */
	__le32 valid_node_count;	/* Total number of valid nodes */
	__le32 valid_inode_count;	/* Total number of valid inodes */
	__le32 next_free_nid;		/* Next free node number */
	__le32 sit_ver_bitmap_bytesize;	/* Default value 64 */
	__le32 nat_ver_bitmap_bytesize; /* Default value 256 */
	__le32 checksum_offset;		/* checksum offset inside cp block */
	__le64 elapsed_time;		/* mounted time */
	/* allocation type of current segment */
	unsigned char alloc_type[MAX_ACTIVE_LOGS];

	/* SIT and NAT version bitmap */
	unsigned char sit_nat_version_bitmap[];
} __packed;

#define CP_CHKSUM_OFFSET	(F2FS_BLKSIZE - sizeof(__le32))	/* default chksum offset in checkpoint */
#define CP_MIN_CHKSUM_OFFSET						\
	(offsetof(struct f2fs_checkpoint, sit_nat_version_bitmap))

/*
 * For orphan inode management
 */
#define F2FS_ORPHANS_PER_BLOCK	((F2FS_BLKSIZE - 4 * sizeof(__le32)) / sizeof(__le32))

#define GET_ORPHAN_BLOCKS(n)	(((n) + F2FS_ORPHANS_PER_BLOCK - 1) / \
					F2FS_ORPHANS_PER_BLOCK)

struct f2fs_orphan_block {
	__le32 ino[F2FS_ORPHANS_PER_BLOCK];	/* inode numbers */
	__le32 reserved;	/* reserved */
	__le16 blk_addr;	/* block index in current CP */
	__le16 blk_count;	/* Number of orphan inode blocks in CP */
	__le32 entry_count;	/* Total number of orphan nodes in current CP */
	__le32 check_sum;	/* CRC32 for orphan inode block */
} __packed;

/*
 * For NODE structure
 */
struct f2fs_extent {
	__le32 fofs;		/* start file offset of the extent */
	__le32 blk;		/* start block address of the extent */
	__le32 len;		/* length of the extent */
} __packed;

#define F2FS_NAME_LEN		255
/* 200 bytes for inline xattrs by default */
#define DEFAULT_INLINE_XATTR_ADDRS	50

#define OFFSET_OF_END_OF_I_EXT		360
#define SIZE_OF_I_NID			20

struct node_footer {
	__le32 nid;		/* node id */
	__le32 ino;		/* inode number */
	__le32 flag;		/* include cold/fsync/dentry marks and offset */
	__le64 cp_ver;		/* checkpoint version */
	__le32 next_blkaddr;	/* next node page block address */
} __packed;

/* Address Pointers in an Inode */
#define DEF_ADDRS_PER_INODE	((F2FS_BLKSIZE - OFFSET_OF_END_OF_I_EXT	\
					- SIZE_OF_I_NID	\
					- sizeof(struct node_footer)) / sizeof(__le32))
#define CUR_ADDRS_PER_INODE(inode)	(DEF_ADDRS_PER_INODE - \
					get_extra_isize(inode))
#define DEF_NIDS_PER_INODE	5	/* Node IDs in an Inode */
#define ADDRS_PER_INODE(inode)	addrs_per_inode(inode)
/* Address Pointers in a Direct Block */
#define DEF_ADDRS_PER_BLOCK	((F2FS_BLKSIZE - sizeof(struct node_footer)) / sizeof(__le32))
#define ADDRS_PER_BLOCK(inode)	addrs_per_block(inode)
/* Node IDs in an Indirect Block */
#define NIDS_PER_BLOCK		((F2FS_BLKSIZE - sizeof(struct node_footer)) / sizeof(__le32))

#define ADDRS_PER_PAGE(page, inode)	\
	(IS_INODE(page) ? ADDRS_PER_INODE(inode) : ADDRS_PER_BLOCK(inode))

#define	NODE_DIR1_BLOCK		(DEF_ADDRS_PER_INODE + 1)
#define	NODE_DIR2_BLOCK		(DEF_ADDRS_PER_INODE + 2)
#define	NODE_IND1_BLOCK		(DEF_ADDRS_PER_INODE + 3)
#define	NODE_IND2_BLOCK		(DEF_ADDRS_PER_INODE + 4)
#define	NODE_DIND_BLOCK		(DEF_ADDRS_PER_INODE + 5)

#define F2FS_INLINE_XATTR	0x01	/* file inline xattr flag */
#define F2FS_INLINE_DATA	0x02	/* file inline data flag */
#define F2FS_INLINE_DENTRY	0x04	/* file inline dentry flag */
#define F2FS_DATA_EXIST		0x08	/* file inline data exist flag */
#define F2FS_INLINE_DOTS	0x10	/* file having implicit dot dentries */
#define F2FS_EXTRA_ATTR		0x20	/* file having extra attribute */
#define F2FS_PIN_FILE		0x40	/* file should not be gced */
#define F2FS_COMPRESS_RELEASED	0x80	/* file released compressed blocks */

struct f2fs_inode {
	__le16 i_mode;			/* file mode */
	__u8 i_advise;			/* file hints */
	__u8 i_inline;			/* file inline flags */
	__le32 i_uid;			/* user ID */
	__le32 i_gid;			/* group ID */
	__le32 i_links;			/* links count */
	__le64 i_size;			/* file size in bytes */
	__le64 i_blocks;		/* file size in blocks */
	__le64 i_atime;			/* access time */
	__le64 i_ctime;			/* change time */
	__le64 i_mtime;			/* modification time */
	__le32 i_atime_nsec;		/* access time in nano scale */
	__le32 i_ctime_nsec;		/* change time in nano scale */
	__le32 i_mtime_nsec;		/* modification time in nano scale */
	__le32 i_generation;		/* file version (for NFS) */
	union {
		__le32 i_current_depth;	/* only for directory depth */
		__le16 i_gc_failures;	/*
					 * # of gc failures on pinned file.
					 * only for regular files.
					 */
	};
	__le32 i_xattr_nid;		/* nid to save xattr */
	__le32 i_flags;			/* file attributes */
	__le32 i_pino;			/* parent inode number */
	__le32 i_namelen;		/* file name length */
	__u8 i_name[F2FS_NAME_LEN];	/* file name for SPOR */
	__u8 i_dir_level;		/* dentry_level for large dir */

	struct f2fs_extent i_ext;	/* caching a largest extent */

	union {
		struct {
			__le16 i_extra_isize;	/* extra inode attribute size */
			__le16 i_inline_xattr_size;	/* inline xattr size, unit: 4 bytes */
			__le32 i_projid;	/* project id */
			__le32 i_inode_checksum;/* inode meta checksum */
			__le64 i_crtime;	/* creation time */
			__le32 i_crtime_nsec;	/* creation time in nano scale */
			__le64 i_compr_blocks;	/* # of compressed blocks */
			__u8 i_compress_algorithm;	/* compress algorithm */
			__u8 i_log_cluster_size;	/* log of cluster size */
			__le16 i_compress_flag;		/* compress flag */
						/* 0 bit: chksum flag
						 * [8,15] bits: compress level
						 */
			__le32 i_extra_end[0];	/* for attribute size calculation */
		} __packed;
		__le32 i_addr[DEF_ADDRS_PER_INODE];	/* Pointers to data blocks */
	};
	__le32 i_nid[DEF_NIDS_PER_INODE];	/* direct(2), indirect(2),
						double_indirect(1) node id */
} __packed;

struct direct_node {
	__le32 addr[DEF_ADDRS_PER_BLOCK];	/* array of data block address */
} __packed;

struct indirect_node {
	__le32 nid[NIDS_PER_BLOCK];	/* array of data block address */
} __packed;

enum {
	COLD_BIT_SHIFT = 0,
	FSYNC_BIT_SHIFT,
	DENT_BIT_SHIFT,
	OFFSET_BIT_SHIFT
};

#define OFFSET_BIT_MASK		GENMASK(OFFSET_BIT_SHIFT - 1, 0)

struct f2fs_node {
	/* can be one of three types: inode, direct, and indirect types */
	union {
		struct f2fs_inode i;
		struct direct_node dn;
		struct indirect_node in;
	};
	struct node_footer footer;
} __packed;

/*
 * For NAT entries
 */
#define NAT_ENTRY_PER_BLOCK (F2FS_BLKSIZE / sizeof(struct f2fs_nat_entry))

struct f2fs_nat_entry {
	__u8 version;		/* latest version of cached nat entry */
	__le32 ino;		/* inode number */
	__le32 block_addr;	/* block address */
} __packed;

struct f2fs_nat_block {
	struct f2fs_nat_entry entries[NAT_ENTRY_PER_BLOCK];
} __packed;

/*
 * For SIT entries
 *
 * A validity bitmap of 64 bytes covers 512 blocks of area. For a 4K page size,
 * this results in a segment size of 2MB. For 16k pages, the default segment size
 * is 8MB.
 * Not allow to change this.
 */
#define SIT_VBLOCK_MAP_SIZE 64
#define SIT_ENTRY_PER_BLOCK (F2FS_BLKSIZE / sizeof(struct f2fs_sit_entry))

/*
 * F2FS uses 4 bytes to represent block address. As a result, supported size of
 * disk is 16 TB and it equals to 16 * 1024 * 1024 / 2 segments.
 */
#define F2FS_MAX_SEGMENT       ((16 * 1024 * 1024) / 2)

/*
 * Note that f2fs_sit_entry->vblocks has the following bit-field information.
 * [15:10] : allocation type such as CURSEG_XXXX_TYPE
 * [9:0] : valid block count
 */
#define SIT_VBLOCKS_SHIFT	10
#define SIT_VBLOCKS_MASK	((1 << SIT_VBLOCKS_SHIFT) - 1)
#define GET_SIT_VBLOCKS(raw_sit)				\
	(le16_to_cpu((raw_sit)->vblocks) & SIT_VBLOCKS_MASK)
#define GET_SIT_TYPE(raw_sit)					\
	((le16_to_cpu((raw_sit)->vblocks) & ~SIT_VBLOCKS_MASK)	\
	 >> SIT_VBLOCKS_SHIFT)

struct f2fs_sit_entry {
	__le16 vblocks;				/* reference above */
	__u8 valid_map[SIT_VBLOCK_MAP_SIZE];	/* bitmap for valid blocks */
	__le64 mtime;				/* segment age for cleaning */
} __packed;

struct f2fs_sit_block {
	struct f2fs_sit_entry entries[SIT_ENTRY_PER_BLOCK];
} __packed;

/*
 * For segment summary
 *
 * One summary block contains exactly 512 summary entries, which represents
 * exactly one segment by default. Not allow to change the basic units.
 *
 * NOTE: For initializing fields, you must use set_summary
 *
 * - If data page, nid represents dnode's nid
 * - If node page, nid represents the node page's nid.
 *
 * The ofs_in_node is used by only data page. It represents offset
 * from node's page's beginning to get a data block address.
 * ex) data_blkaddr = (block_t)(nodepage_start_address + ofs_in_node)
 */
#define ENTRIES_IN_SUM		(F2FS_BLKSIZE / 8)
#define	SUMMARY_SIZE		(7)	/* sizeof(struct f2fs_summary) */
#define	SUM_FOOTER_SIZE		(5)	/* sizeof(struct summary_footer) */
#define SUM_ENTRY_SIZE		(SUMMARY_SIZE * ENTRIES_IN_SUM)

/* a summary entry for a block in a segment */
struct f2fs_summary {
	__le32 nid;		/* parent node id */
	union {
		__u8 reserved[3];
		struct {
			__u8 version;		/* node version number */
			__le16 ofs_in_node;	/* block index in parent node */
		} __packed;
	};
} __packed;

/* summary block type, node or data, is stored to the summary_footer */
#define SUM_TYPE_NODE		(1)
#define SUM_TYPE_DATA		(0)

struct summary_footer {
	unsigned char entry_type;	/* SUM_TYPE_XXX */
	__le32 check_sum;		/* summary checksum */
} __packed;

#define SUM_JOURNAL_SIZE	(F2FS_BLKSIZE - SUM_FOOTER_SIZE -\
				SUM_ENTRY_SIZE)
#define NAT_JOURNAL_ENTRIES	((SUM_JOURNAL_SIZE - 2) /\
				sizeof(struct nat_journal_entry))
#define NAT_JOURNAL_RESERVED	((SUM_JOURNAL_SIZE - 2) %\
				sizeof(struct nat_journal_entry))
#define SIT_JOURNAL_ENTRIES	((SUM_JOURNAL_SIZE - 2) /\
				sizeof(struct sit_journal_entry))
#define SIT_JOURNAL_RESERVED	((SUM_JOURNAL_SIZE - 2) %\
				sizeof(struct sit_journal_entry))

/* Reserved area should make size of f2fs_extra_info equals to
 * that of nat_journal and sit_journal.
 */
#define EXTRA_INFO_RESERVED	(SUM_JOURNAL_SIZE - 2 - 8)

/*
 * frequently updated NAT/SIT entries can be stored in the spare area in
 * summary blocks
 */
enum {
	NAT_JOURNAL = 0,
	SIT_JOURNAL
};

struct nat_journal_entry {
	__le32 nid;
	struct f2fs_nat_entry ne;
} __packed;

struct nat_journal {
	struct nat_journal_entry entries[NAT_JOURNAL_ENTRIES];
	__u8 reserved[NAT_JOURNAL_RESERVED];
} __packed;

struct sit_journal_entry {
	__le32 segno;
	struct f2fs_sit_entry se;
} __packed;

struct sit_journal {
	struct sit_journal_entry entries[SIT_JOURNAL_ENTRIES];
	__u8 reserved[SIT_JOURNAL_RESERVED];
} __packed;

struct f2fs_extra_info {
	__le64 kbytes_written;
	__u8 reserved[EXTRA_INFO_RESERVED];
} __packed;

struct f2fs_journal {
	union {
		__le16 n_nats;
		__le16 n_sits;
	};
	/* spare area is used by NAT or SIT journals or extra info */
	union {
		struct nat_journal nat_j;
		struct sit_journal sit_j;
		struct f2fs_extra_info info;
	};
} __packed;

/* Block-sized summary block structure */
struct f2fs_summary_block {
	struct f2fs_summary entries[ENTRIES_IN_SUM];
	struct f2fs_journal journal;
	struct summary_footer footer;
} __packed;

/*
 * For directory operations
 */
#define F2FS_DOT_HASH		0
#define F2FS_DDOT_HASH		F2FS_DOT_HASH
#define F2FS_MAX_HASH		(~((0x3ULL) << 62))
#define F2FS_HASH_COL_BIT	((0x1ULL) << 63)

typedef __le32	f2fs_hash_t;

/* One directory entry slot covers 8bytes-long file name */
#define F2FS_SLOT_LEN		8
#define F2FS_SLOT_LEN_BITS	3

#define GET_DENTRY_SLOTS(x) (((x) + F2FS_SLOT_LEN - 1) >> F2FS_SLOT_LEN_BITS)

/* MAX level for dir lookup */
#define MAX_DIR_HASH_DEPTH	63

/* MAX buckets in one level of dir */
#define MAX_DIR_BUCKETS		BIT((MAX_DIR_HASH_DEPTH / 2) - 1)

/*
 * space utilization of regular dentry and inline dentry (w/o extra reservation)
 *		regular dentry		inline dentry (def)	inline dentry (min)
 * bitmap	1 * 27 = 27		1 * 23 = 23		1 * 1 = 1
 * reserved	1 * 3 = 3		1 * 7 = 7		1 * 1 = 1
 * dentry	11 * 214 = 2354		11 * 182 = 2002		11 * 2 = 22
 * filename	8 * 214 = 1712		8 * 182 = 1456		8 * 2 = 16
 * total	4096			3488			40
 *
 * Note: there are more reserved space in inline dentry than in regular
 * dentry, when converting inline dentry we should handle this carefully.
 */

/* the number of dentry in a block */
#define NR_DENTRY_IN_BLOCK	((BITS_PER_BYTE * F2FS_BLKSIZE) / \
					((SIZE_OF_DIR_ENTRY + F2FS_SLOT_LEN) * BITS_PER_BYTE + 1))
#define SIZE_OF_DIR_ENTRY	11	/* by byte */
#define SIZE_OF_DENTRY_BITMAP	((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
					BITS_PER_BYTE)
#define SIZE_OF_RESERVED	(F2FS_BLKSIZE - ((SIZE_OF_DIR_ENTRY + \
				F2FS_SLOT_LEN) * \
				NR_DENTRY_IN_BLOCK + SIZE_OF_DENTRY_BITMAP))
#define MIN_INLINE_DENTRY_SIZE		40	/* just include '.' and '..' entries */

/* One directory entry slot representing F2FS_SLOT_LEN-sized file name */
struct f2fs_dir_entry {
	__le32 hash_code;	/* hash code of file name */
	__le32 ino;		/* inode number */
	__le16 name_len;	/* length of file name */
	__u8 file_type;		/* file type */
} __packed;

/* Block-sized directory entry block */
struct f2fs_dentry_block {
	/* validity bitmap for directory entries in each block */
	__u8 dentry_bitmap[SIZE_OF_DENTRY_BITMAP];
	__u8 reserved[SIZE_OF_RESERVED];
	struct f2fs_dir_entry dentry[NR_DENTRY_IN_BLOCK];
	__u8 filename[NR_DENTRY_IN_BLOCK][F2FS_SLOT_LEN];
} __packed;

#define	F2FS_DEF_PROJID		0	/* default project ID */

#endif  /* _LINUX_F2FS_FS_H */