f2fs: add on-disk layout

This adds a header file describing the on-disk layout of f2fs.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Chul Lee <chur.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

1 files changed, 410 insertions, 0 deletions

diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
new file mode 100644
index 000000000000..1429ece7caab
--- /dev/null
+++ b/include/linux/f2fs_fs.h
@@ -0,0 +1,410 @@
+/**
+ * include/linux/f2fs_fs.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * 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.
+ */
+#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_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
+
+#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)
+
+/* 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
+
+/*
+ * For superblock
+ */
+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 */
+} __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];
+} __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 */
+} __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 */
+} __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 */
+} __packed;
+
+struct direct_node {
+        __le32 addr[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
+};
+
+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 */
+} __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;
+} __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 */
+} __packed;
+
+struct f2fs_nat_block {
+        struct f2fs_nat_entry entries[NAT_ENTRY_PER_BLOCK];
+} __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)
+
+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 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 */
+                } __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 */
+        __u32 check_sum;                /* summary checksum */
+} __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;
+} __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;
+
+/* 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;
+} __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_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 */
+} __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];
+} __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
+};
+
+#endif  /* _LINUX_F2FS_FS_H */