f2fs_layout.h

// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef F2FS_FORMAT_H_
#define F2FS_FORMAT_H_

#include "f2fs_types.h"

namespace f2fs {

#define F2FS_SUPER_OFFSET 1024       /* byte-size offset */
#define F2FS_LOG_SECTOR_SIZE 9       /* 9 bits for 512 byte */
#define F2FS_LOG_SECTORS_PER_BLOCK 3 /* 4KB: F2FS_BLKSIZE */
#define F2FS_BLKSIZE 4096            /* support only 4KB block */
#define F2FS_MAX_EXTENSION 64        /* # of extension entries */

#define NULL_ADDR 0x0U
#define NEW_ADDR (-1U)

// sukka
#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 NULL_ADDR 0x0U  // from f2fs_fs.h

constexpr uint32_t kF2fsBlockSize = 4096;

// Superblock location.
constexpr size_t kSuperblockStart = 0;

/* for mkfs */
#define F2FS_MIN_VOLUME_SIZE 104857600

#define F2FS_MAJOR_VERSION 1
#define F2FS_MINOR_VERSION 0

#define F2FS_O_DIRECTORY 0x00004000
#define F2FS_O_EONLY 0x00000040
#define F2FS_O_WRONLY 0x00000080
#define F2FS_O_RDONLY 0x00000100

#define F2FS_NUMBER_OF_CHECKPOINT_PACK 2

#define DEFAULT_SECTOR_SIZE 512
#define DEFAULT_SECTORS_PER_BLOCK 8
#define DEFAULT_BLOCKS_PER_SEGMENT 512
#define DEFAULT_SEGMENTS_PER_SECTION 1
#define F2FS_CP_BLOCK_SIZE (DEFAULT_SECTOR_SIZE * DEFAULT_SECTORS_PER_BLOCK)

/*
 * 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

struct f2fs_global_parameters {
  uint32_t sector_size;
  uint32_t reserved_segments;
  uint32_t overprovision;
  uint32_t cur_seg[6];
  uint32_t segs_per_sec;
  uint32_t secs_per_zone;
  uint32_t start_sector;
  uint64_t total_sectors;
  uint32_t sectors_per_blk;
  uint32_t blks_per_seg;
  uint8_t vol_label[16];
  int heap;
  int32_t fd;
  char *device_name;
  char *extension_list;
} __attribute__((packed));

#define BITS_PER_LONG 64

#define BIT_MASK(nr) (1 << ((nr) % BITS_PER_LONG))
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)

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[512];                    /* volume name */
  __le32 extension_count;                     /* # of extensions below */
  __u8 extension_list[F2FS_MAX_EXTENSION][8]; /* extension array */
} __attribute__((packed));

/*
 * For checkpoint
 */
#define CP_ERROR_FLAG 0x00000008
#define CP_COMPACT_SUM_FLAG 0x00000004
#define CP_ORPHAN_PRESENT_FLAG 0x00000002
#define CP_UMOUNT_FLAG 0x00000001

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[1];
} __attribute__((packed));

/*
 * For orphan inode management
 */
#define F2FS_ORPHANS_PER_BLOCK 1020

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 */
} __attribute__((packed));

/*
 * For NODE structure
 */
struct f2fs_extent {
  __le32 fofs;     /* start file offset of the extent */
  __le32 blk_addr; /* start block address of the extent */
  __le32 len;      /* lengh of the extent */
} __attribute__((packed));

#define F2FS_MAX_NAME_LEN 256
#define ADDRS_PER_INODE 923  /* Address Pointers in an Inode */
#define ADDRS_PER_BLOCK 1018 /* Address Pointers in a Direct Block */
#define NIDS_PER_BLOCK 1018  /* Node IDs in an Indirect Block */

struct f2fs_inode {
  __le16 i_mode;                  /* file mode */
  __u8 i_advise;                  /* file hints */
  __u8 i_reserved;                /* reserved */
  __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) */
  __le32 i_current_depth;         /* only for directory depth */
  __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_MAX_NAME_LEN]; /* file name for SPOR */

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

  __le32 i_addr[ADDRS_PER_INODE]; /* Pointers to data blocks */

  __le32 i_nid[5]; /* direct(2), indirect(2),
                           double_indirect(1) node id */
} __attribute__((packed));

struct direct_node {
  __le32 addr[ADDRS_PER_BLOCK]; /* aray of data block address */
} __attribute__((packed));

struct indirect_node {
  __le32 nid[NIDS_PER_BLOCK]; /* aray of data block address */
} __attribute__((packed));

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

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

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;
} __attribute__((packed));

/*
 * For NAT entries
 */
#define NAT_ENTRY_PER_BLOCK (PAGE_CACHE_SIZE / 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 */
} __attribute__((packed));

struct f2fs_nat_block {
  struct f2fs_nat_entry entries[NAT_ENTRY_PER_BLOCK];
} __attribute__((packed));

/*
 * For SIT entries
 *
 * Each segment is 2MB in size by default so that a bitmap for validity of
 * there-in blocks should occupy 64 bytes, 512 bits.
 * Not allow to change this.
 */
#define SIT_VBLOCK_MAP_SIZE 64
#define SIT_ENTRY_PER_BLOCK (PAGE_CACHE_SIZE / sizeof(struct f2fs_sit_entry))

/*
 * 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)

/*
 * 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 CURSEG_NULL ((-1 << 10) >> 10) /* use 6bit - 0x3f */

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 */
} __attribute__((packed));

struct f2fs_sit_block {
  struct f2fs_sit_entry entries[SIT_ENTRY_PER_BLOCK];
} __attribute__((packed));

/**
 * For segment summary
 *
 * One summary block contains exactly 512 summary entries, which represents
 * exactly 2MB 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 512
#define SUMMARY_SIZE (sizeof(struct f2fs_summary))
#define SUM_FOOTER_SIZE (sizeof(struct summary_footer))
#define SUM_ENTRY_SIZE (SUMMARY_SIZE * ENTRIES_IN_SUM)

/* a summary entry for a 4KB-sized 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 */
    } __attribute__((packed));
  };
} __attribute__((packed));

/* summary block type, node or data, is stored to the summary_footer */
#define SUM_TYPE_NODE (1)
#define SUM_TYPE_DATA (0)
#define GET_SUM_TYPE(footer) (footer->entry_type)
#define SET_SUM_TYPE(footer, type) (footer->entry_type = type)

struct summary_footer {
  unsigned char entry_type; /* SUM_TYPE_XXX */
  __u32 check_sum;          /* summary checksum */
} __attribute__((packed));

#define SUM_JOURNAL_SIZE (PAGE_CACHE_SIZE - 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))
/*
 * 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;
} __attribute__((packed));

struct nat_journal {
  struct nat_journal_entry entries[NAT_JOURNAL_ENTRIES];
  __u8 reserved[NAT_JOURNAL_RESERVED];
} __attribute__((packed));

struct sit_journal_entry {
  __le32 segno;
  struct f2fs_sit_entry se;
} __attribute__((packed));

struct sit_journal {
  struct sit_journal_entry entries[SIT_JOURNAL_ENTRIES];
  __u8 reserved[SIT_JOURNAL_RESERVED];
} __attribute__((packed));

/* 4KB-sized summary block structure */
struct f2fs_summary_block {
  struct f2fs_summary entries[ENTRIES_IN_SUM];
  union {
    __le16 n_nats;
    __le16 n_sits;
  };
  /* spare area is used by NAT or SIT journals */
  union {
    struct nat_journal nat_j;
    struct sit_journal sit_j;
  };
  struct summary_footer footer;
} __attribute__((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)

using f2fs_hash_t = __le32;

/* One directory entry slot covers 8bytes-long file name */
#define F2FS_NAME_LEN 8

/* the number of dentry in a block */
#define NR_DENTRY_IN_BLOCK 214

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

#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 \
  (PAGE_SIZE - ((SIZE_OF_DIR_ENTRY + F2FS_NAME_LEN) * NR_DENTRY_IN_BLOCK + SIZE_OF_DENTRY_BITMAP))

/* One directory entry slot representing F2FS_NAME_LEN-sized file name */
struct f2fs_dir_entry {
  __le32 hash_code; /* hash code of file name */
  __le32 ino;       /* inode number */
  __le16 name_len;  /* lengh of file name */
  __u8 file_type;   /* file type */
} __attribute__((packed));

/* 4KB-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_NAME_LEN];
} __attribute__((packed));

/* file types used in inode_info->flags */
enum {
  F2FS_FT_UNKNOWN,
  F2FS_FT_REG_FILE,
  F2FS_FT_DIR,
  F2FS_FT_CHRDEV,
  F2FS_FT_BLKDEV,
  F2FS_FT_FIFO,
  F2FS_FT_SOCK,
  F2FS_FT_SYMLINK,
  F2FS_FT_MAX
};

constexpr uint32_t kF2fsHashBits = (8);

}  // namespace f2fs

#endif  //__F2FS_FORMAT_H__