ext4.h

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/*
 *  ext4.h
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([email protected])
 * 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 _EXT4_H
#define _EXT4_H

#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/magic.h>
#include <linux/jbd2.h>
#include <linux/quota.h>
#include <linux/rwsem.h>
#include <linux/rbtree.h>
#include <linux/seqlock.h>
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/blockgroup_lock.h>
#include <linux/percpu_counter.h>
#include <crypto/hash.h>
#ifdef __KERNEL__
#include <linux/compat.h>
#endif

/*
 * The fourth extended filesystem constants/structures
 */

/*
 * Define EXT4FS_DEBUG to produce debug messages
 */
#undef EXT4FS_DEBUG

/*
 * Debug code
 */
#ifdef EXT4FS_DEBUG
#define ext4_debug(f, a...)                     \
    do {                                \
        printk(KERN_DEBUG "EXT4-fs DEBUG (%s, %d): %s:",    \
            __FILE__, __LINE__, __func__);          \
        printk(KERN_DEBUG f, ## a);             \
    } while (0)
#else
#define ext4_debug(fmt, ...)    no_printk(fmt, ##__VA_ARGS__)
#endif

#define EXT4_ERROR_INODE(inode, fmt, a...) \
    ext4_error_inode((inode), __func__, __LINE__, 0, (fmt), ## a)

#define EXT4_ERROR_INODE_BLOCK(inode, block, fmt, a...)         \
    ext4_error_inode((inode), __func__, __LINE__, (block), (fmt), ## a)

#define EXT4_ERROR_FILE(file, block, fmt, a...)             \
    ext4_error_file((file), __func__, __LINE__, (block), (fmt), ## a)

/* data type for block offset of block group */
typedef int ext4_grpblk_t;

/* data type for filesystem-wide blocks number */
typedef unsigned long long ext4_fsblk_t;

/* data type for file logical block number */
typedef __u32 ext4_lblk_t;

/* data type for block group number */
typedef unsigned int ext4_group_t;

/*
 * Flags used in mballoc's allocation_context flags field.
 *
 * Also used to show what's going on for debugging purposes when the
 * flag field is exported via the traceport interface
 */

/* prefer goal again. length */
#define EXT4_MB_HINT_MERGE      0x0001
/* blocks already reserved */
#define EXT4_MB_HINT_RESERVED       0x0002
/* metadata is being allocated */
#define EXT4_MB_HINT_METADATA       0x0004
/* first blocks in the file */
#define EXT4_MB_HINT_FIRST      0x0008
/* search for the best chunk */
#define EXT4_MB_HINT_BEST       0x0010
/* data is being allocated */
#define EXT4_MB_HINT_DATA       0x0020
/* don't preallocate (for tails) */
#define EXT4_MB_HINT_NOPREALLOC     0x0040
/* allocate for locality group */
#define EXT4_MB_HINT_GROUP_ALLOC    0x0080
/* allocate goal blocks or none */
#define EXT4_MB_HINT_GOAL_ONLY      0x0100
/* goal is meaningful */
#define EXT4_MB_HINT_TRY_GOAL       0x0200
/* blocks already pre-reserved by delayed allocation */
#define EXT4_MB_DELALLOC_RESERVED   0x0400
/* We are doing stream allocation */
#define EXT4_MB_STREAM_ALLOC        0x0800
/* Use reserved root blocks if needed */
#define EXT4_MB_USE_ROOT_BLOCKS     0x1000

struct ext4_allocation_request {
    /* target inode for block we're allocating */
    struct inode *inode;
    /* how many blocks we want to allocate */
    unsigned int len;
    /* logical block in target inode */
    ext4_lblk_t logical;
    /* the closest logical allocated block to the left */
    ext4_lblk_t lleft;
    /* the closest logical allocated block to the right */
    ext4_lblk_t lright;
    /* phys. target (a hint) */
    ext4_fsblk_t goal;
    /* phys. block for the closest logical allocated block to the left */
    ext4_fsblk_t pleft;
    /* phys. block for the closest logical allocated block to the right */
    ext4_fsblk_t pright;
    /* flags. see above EXT4_MB_HINT_* */
    unsigned int flags;
};

/*
 * Logical to physical block mapping, used by ext4_map_blocks()
 *
 * This structure is used to pass requests into ext4_map_blocks() as
 * well as to store the information returned by ext4_map_blocks().  It
 * takes less room on the stack than a struct buffer_head.
 */
#define EXT4_MAP_NEW        (1 << BH_New)
#define EXT4_MAP_MAPPED     (1 << BH_Mapped)
#define EXT4_MAP_UNWRITTEN  (1 << BH_Unwritten)
#define EXT4_MAP_BOUNDARY   (1 << BH_Boundary)
#define EXT4_MAP_UNINIT     (1 << BH_Uninit)
/* Sometimes (in the bigalloc case, from ext4_da_get_block_prep) the caller of
 * ext4_map_blocks wants to know whether or not the underlying cluster has
 * already been accounted for. EXT4_MAP_FROM_CLUSTER conveys to the caller that
 * the requested mapping was from previously mapped (or delayed allocated)
 * cluster. We use BH_AllocFromCluster only for this flag. BH_AllocFromCluster
 * should never appear on buffer_head's state flags.
 */
#define EXT4_MAP_FROM_CLUSTER   (1 << BH_AllocFromCluster)
#define EXT4_MAP_FLAGS      (EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
                 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
                 EXT4_MAP_UNINIT | EXT4_MAP_FROM_CLUSTER)

struct ext4_map_blocks {
    ext4_fsblk_t m_pblk;
    ext4_lblk_t m_lblk;
    unsigned int m_len;
    unsigned int m_flags;
};

/*
 * For delayed allocation tracking
 */
struct mpage_da_data {
    struct inode *inode;
    sector_t b_blocknr;     /* start block number of extent */
    size_t b_size;          /* size of extent */
    unsigned long b_state;      /* state of the extent */
    unsigned long first_page, next_page;    /* extent of pages */
    struct writeback_control *wbc;
    int io_done;
    int pages_written;
    int retval;
};

/*
 * Flags for ext4_io_end->flags
 */
#define EXT4_IO_END_UNWRITTEN   0x0001
#define EXT4_IO_END_ERROR   0x0002
#define EXT4_IO_END_QUEUED  0x0004
#define EXT4_IO_END_DIRECT  0x0008

struct ext4_io_page {
    struct page *p_page;
    atomic_t    p_count;
};

#define MAX_IO_PAGES 128

/*
 * For converting uninitialized extents on a work queue.
 *
 * 'page' is only used from the writepage() path; 'pages' is only used for
 * buffered writes; they are used to keep page references until conversion
 * takes place.  For AIO/DIO, neither field is filled in.
 */
typedef struct ext4_io_end {
    struct list_head    list;       /* per-file finished IO list */
    struct inode        *inode;     /* file being written to */
    unsigned int        flag;       /* unwritten or not */
    struct page     *page;      /* for writepage() path */
    loff_t          offset;     /* offset in the file */
    ssize_t         size;       /* size of the extent */
    struct work_struct  work;       /* data work queue */
    struct kiocb        *iocb;      /* iocb struct for AIO */
    int         result;     /* error value for AIO */
    int         num_io_pages;   /* for writepages() */
    struct ext4_io_page *pages[MAX_IO_PAGES]; /* for writepages() */
} ext4_io_end_t;

struct ext4_io_submit {
    int         io_op;
    struct bio      *io_bio;
    ext4_io_end_t       *io_end;
    struct ext4_io_page *io_page;
    sector_t        io_next_block;
};

/*
 * Special inodes numbers
 */
#define EXT4_BAD_INO         1  /* Bad blocks inode */
#define EXT4_ROOT_INO        2  /* Root inode */
#define EXT4_USR_QUOTA_INO   3  /* User quota inode */
#define EXT4_GRP_QUOTA_INO   4  /* Group quota inode */
#define EXT4_BOOT_LOADER_INO     5  /* Boot loader inode */
#define EXT4_UNDEL_DIR_INO   6  /* Undelete directory inode */
#define EXT4_RESIZE_INO      7  /* Reserved group descriptors inode */
#define EXT4_JOURNAL_INO     8  /* Journal inode */

/* First non-reserved inode for old ext4 filesystems */
#define EXT4_GOOD_OLD_FIRST_INO 11

/*
 * Maximal count of links to a file
 */
#define EXT4_LINK_MAX       65000

/*
 * Macro-instructions used to manage several block sizes
 */
#define EXT4_MIN_BLOCK_SIZE     1024
#define EXT4_MAX_BLOCK_SIZE     65536
#define EXT4_MIN_BLOCK_LOG_SIZE     10
#define EXT4_MAX_BLOCK_LOG_SIZE     16
#ifdef __KERNEL__
# define EXT4_BLOCK_SIZE(s)     ((s)->s_blocksize)
#else
# define EXT4_BLOCK_SIZE(s)     (EXT4_MIN_BLOCK_SIZE << (s)->s_log_block_size)
#endif
#define EXT4_ADDR_PER_BLOCK(s)      (EXT4_BLOCK_SIZE(s) / sizeof(__u32))
#define EXT4_CLUSTER_SIZE(s)        (EXT4_BLOCK_SIZE(s) << \
                     EXT4_SB(s)->s_cluster_bits)
#ifdef __KERNEL__
# define EXT4_BLOCK_SIZE_BITS(s)    ((s)->s_blocksize_bits)
# define EXT4_CLUSTER_BITS(s)       (EXT4_SB(s)->s_cluster_bits)
#else
# define EXT4_BLOCK_SIZE_BITS(s)    ((s)->s_log_block_size + 10)
#endif
#ifdef __KERNEL__
#define EXT4_ADDR_PER_BLOCK_BITS(s) (EXT4_SB(s)->s_addr_per_block_bits)
#define EXT4_INODE_SIZE(s)      (EXT4_SB(s)->s_inode_size)
#define EXT4_FIRST_INO(s)       (EXT4_SB(s)->s_first_ino)
#else
#define EXT4_INODE_SIZE(s)  (((s)->s_rev_level == EXT4_GOOD_OLD_REV) ? \
                 EXT4_GOOD_OLD_INODE_SIZE : \
                 (s)->s_inode_size)
#define EXT4_FIRST_INO(s)   (((s)->s_rev_level == EXT4_GOOD_OLD_REV) ? \
                 EXT4_GOOD_OLD_FIRST_INO : \
                 (s)->s_first_ino)
#endif
#define EXT4_BLOCK_ALIGN(size, blkbits)     ALIGN((size), (1 << (blkbits)))

/* Translate a block number to a cluster number */
#define EXT4_B2C(sbi, blk)  ((blk) >> (sbi)->s_cluster_bits)
/* Translate a cluster number to a block number */
#define EXT4_C2B(sbi, cluster)  ((cluster) << (sbi)->s_cluster_bits)
/* Translate # of blks to # of clusters */
#define EXT4_NUM_B2C(sbi, blks) (((blks) + (sbi)->s_cluster_ratio - 1) >> \
                 (sbi)->s_cluster_bits)

/*
 * Structure of a blocks group descriptor
 */
struct ext4_group_desc
{
    __le32  bg_block_bitmap_lo; /* Blocks bitmap block */
    __le32  bg_inode_bitmap_lo; /* Inodes bitmap block */
    __le32  bg_inode_table_lo;  /* Inodes table block */
    __le16  bg_free_blocks_count_lo;/* Free blocks count */
    __le16  bg_free_inodes_count_lo;/* Free inodes count */
    __le16  bg_used_dirs_count_lo;  /* Directories count */
    __le16  bg_flags;       /* EXT4_BG_flags (INODE_UNINIT, etc) */
    __le32  bg_exclude_bitmap_lo;   /* Exclude bitmap for snapshots */
    __le16  bg_block_bitmap_csum_lo;/* crc32c(s_uuid+grp_num+bbitmap) LE */
    __le16  bg_inode_bitmap_csum_lo;/* crc32c(s_uuid+grp_num+ibitmap) LE */
    __le16  bg_itable_unused_lo;    /* Unused inodes count */
    __le16  bg_checksum;        /* crc16(sb_uuid+group+desc) */
    __le32  bg_block_bitmap_hi; /* Blocks bitmap block MSB */
    __le32  bg_inode_bitmap_hi; /* Inodes bitmap block MSB */
    __le32  bg_inode_table_hi;  /* Inodes table block MSB */
    __le16  bg_free_blocks_count_hi;/* Free blocks count MSB */
    __le16  bg_free_inodes_count_hi;/* Free inodes count MSB */
    __le16  bg_used_dirs_count_hi;  /* Directories count MSB */
    __le16  bg_itable_unused_hi;    /* Unused inodes count MSB */
    __le32  bg_exclude_bitmap_hi;   /* Exclude bitmap block MSB */
    __le16  bg_block_bitmap_csum_hi;/* crc32c(s_uuid+grp_num+bbitmap) BE */
    __le16  bg_inode_bitmap_csum_hi;/* crc32c(s_uuid+grp_num+ibitmap) BE */
    __u32   bg_reserved;
};

#define EXT4_BG_INODE_BITMAP_CSUM_HI_END    \
    (offsetof(struct ext4_group_desc, bg_inode_bitmap_csum_hi) + \
     sizeof(__le16))
#define EXT4_BG_BLOCK_BITMAP_CSUM_HI_END    \
    (offsetof(struct ext4_group_desc, bg_block_bitmap_csum_hi) + \
     sizeof(__le16))

/*
 * Structure of a flex block group info
 */

struct flex_groups {
    atomic_t free_inodes;
    atomic_t free_clusters;
    atomic_t used_dirs;
};

#define EXT4_BG_INODE_UNINIT    0x0001 /* Inode table/bitmap not in use */
#define EXT4_BG_BLOCK_UNINIT    0x0002 /* Block bitmap not in use */
#define EXT4_BG_INODE_ZEROED    0x0004 /* On-disk itable initialized to zero */

/*
 * Macro-instructions used to manage group descriptors
 */
#define EXT4_MIN_DESC_SIZE      32
#define EXT4_MIN_DESC_SIZE_64BIT    64
#define EXT4_MAX_DESC_SIZE      EXT4_MIN_BLOCK_SIZE
#define EXT4_DESC_SIZE(s)       (EXT4_SB(s)->s_desc_size)
#ifdef __KERNEL__
# define EXT4_BLOCKS_PER_GROUP(s)   (EXT4_SB(s)->s_blocks_per_group)
# define EXT4_CLUSTERS_PER_GROUP(s) (EXT4_SB(s)->s_clusters_per_group)
# define EXT4_DESC_PER_BLOCK(s)     (EXT4_SB(s)->s_desc_per_block)
# define EXT4_INODES_PER_GROUP(s)   (EXT4_SB(s)->s_inodes_per_group)
# define EXT4_DESC_PER_BLOCK_BITS(s)    (EXT4_SB(s)->s_desc_per_block_bits)
#else
# define EXT4_BLOCKS_PER_GROUP(s)   ((s)->s_blocks_per_group)
# define EXT4_DESC_PER_BLOCK(s)     (EXT4_BLOCK_SIZE(s) / EXT4_DESC_SIZE(s))
# define EXT4_INODES_PER_GROUP(s)   ((s)->s_inodes_per_group)
#endif

/*
 * Constants relative to the data blocks
 */
#define EXT4_NDIR_BLOCKS        12
#define EXT4_IND_BLOCK          EXT4_NDIR_BLOCKS
#define EXT4_DIND_BLOCK         (EXT4_IND_BLOCK + 1)
#define EXT4_TIND_BLOCK         (EXT4_DIND_BLOCK + 1)
#define EXT4_N_BLOCKS           (EXT4_TIND_BLOCK + 1)

/*
 * Inode flags
 */
#define EXT4_SECRM_FL           0x00000001 /* Secure deletion */
#define EXT4_UNRM_FL            0x00000002 /* Undelete */
#define EXT4_COMPR_FL           0x00000004 /* Compress file */
#define EXT4_SYNC_FL            0x00000008 /* Synchronous updates */
#define EXT4_IMMUTABLE_FL       0x00000010 /* Immutable file */
#define EXT4_APPEND_FL          0x00000020 /* writes to file may only append */
#define EXT4_NODUMP_FL          0x00000040 /* do not dump file */
#define EXT4_NOATIME_FL         0x00000080 /* do not update atime */
/* Reserved for compression usage... */
#define EXT4_DIRTY_FL           0x00000100
#define EXT4_COMPRBLK_FL        0x00000200 /* One or more compressed clusters */
#define EXT4_NOCOMPR_FL         0x00000400 /* Don't compress */
#define EXT4_ECOMPR_FL          0x00000800 /* Compression error */
/* End compression flags --- maybe not all used */
#define EXT4_INDEX_FL           0x00001000 /* hash-indexed directory */
#define EXT4_IMAGIC_FL          0x00002000 /* AFS directory */
#define EXT4_JOURNAL_DATA_FL        0x00004000 /* file data should be journaled */
#define EXT4_NOTAIL_FL          0x00008000 /* file tail should not be merged */
#define EXT4_DIRSYNC_FL         0x00010000 /* dirsync behaviour (directories only) */
#define EXT4_TOPDIR_FL          0x00020000 /* Top of directory hierarchies*/
#define EXT4_HUGE_FILE_FL               0x00040000 /* Set to each huge file */
#define EXT4_EXTENTS_FL         0x00080000 /* Inode uses extents */
#define EXT4_EA_INODE_FL            0x00200000 /* Inode used for large EA */
#define EXT4_EOFBLOCKS_FL       0x00400000 /* Blocks allocated beyond EOF */
#define EXT4_RESERVED_FL        0x80000000 /* reserved for ext4 lib */

#define EXT4_FL_USER_VISIBLE        0x004BDFFF /* User visible flags */
#define EXT4_FL_USER_MODIFIABLE     0x004B80FF /* User modifiable flags */

/* Flags that should be inherited by new inodes from their parent. */
#define EXT4_FL_INHERITED (EXT4_SECRM_FL | EXT4_UNRM_FL | EXT4_COMPR_FL |\
               EXT4_SYNC_FL | EXT4_NODUMP_FL | EXT4_NOATIME_FL |\
               EXT4_NOCOMPR_FL | EXT4_JOURNAL_DATA_FL |\
               EXT4_NOTAIL_FL | EXT4_DIRSYNC_FL)

/* Flags that are appropriate for regular files (all but dir-specific ones). */
#define EXT4_REG_FLMASK (~(EXT4_DIRSYNC_FL | EXT4_TOPDIR_FL))

/* Flags that are appropriate for non-directories/regular files. */
#define EXT4_OTHER_FLMASK (EXT4_NODUMP_FL | EXT4_NOATIME_FL)

/* Mask out flags that are inappropriate for the given type of inode. */
static inline __u32 ext4_mask_flags(umode_t mode, __u32 flags)
{
    if (S_ISDIR(mode))
        return flags;
    else if (S_ISREG(mode))
        return flags & EXT4_REG_FLMASK;
    else
        return flags & EXT4_OTHER_FLMASK;
}

/*
 * Inode flags used for atomic set/get
 */
enum {
    EXT4_INODE_SECRM    = 0,    /* Secure deletion */
    EXT4_INODE_UNRM     = 1,    /* Undelete */
    EXT4_INODE_COMPR    = 2,    /* Compress file */
    EXT4_INODE_SYNC     = 3,    /* Synchronous updates */
    EXT4_INODE_IMMUTABLE    = 4,    /* Immutable file */
    EXT4_INODE_APPEND   = 5,    /* writes to file may only append */
    EXT4_INODE_NODUMP   = 6,    /* do not dump file */
    EXT4_INODE_NOATIME  = 7,    /* do not update atime */
/* Reserved for compression usage... */
    EXT4_INODE_DIRTY    = 8,
    EXT4_INODE_COMPRBLK = 9,    /* One or more compressed clusters */
    EXT4_INODE_NOCOMPR  = 10,   /* Don't compress */
    EXT4_INODE_ECOMPR   = 11,   /* Compression error */
/* End compression flags --- maybe not all used */
    EXT4_INODE_INDEX    = 12,   /* hash-indexed directory */
    EXT4_INODE_IMAGIC   = 13,   /* AFS directory */
    EXT4_INODE_JOURNAL_DATA = 14,   /* file data should be journaled */
    EXT4_INODE_NOTAIL   = 15,   /* file tail should not be merged */
    EXT4_INODE_DIRSYNC  = 16,   /* dirsync behaviour (directories only) */
    EXT4_INODE_TOPDIR   = 17,   /* Top of directory hierarchies*/
    EXT4_INODE_HUGE_FILE    = 18,   /* Set to each huge file */
    EXT4_INODE_EXTENTS  = 19,   /* Inode uses extents */
    EXT4_INODE_EA_INODE = 21,   /* Inode used for large EA */
    EXT4_INODE_EOFBLOCKS    = 22,   /* Blocks allocated beyond EOF */
    EXT4_INODE_RESERVED = 31,   /* reserved for ext4 lib */
};

#define TEST_FLAG_VALUE(FLAG) (EXT4_##FLAG##_FL == (1 << EXT4_INODE_##FLAG))
#define CHECK_FLAG_VALUE(FLAG) if (!TEST_FLAG_VALUE(FLAG)) { \
    printk(KERN_EMERG "EXT4 flag fail: " #FLAG ": %d %d\n", \
        EXT4_##FLAG##_FL, EXT4_INODE_##FLAG); BUG_ON(1); }

/*
 * Since it's pretty easy to mix up bit numbers and hex values, and we
 * can't do a compile-time test for ENUM values, we use a run-time
 * test to make sure that EXT4_XXX_FL is consistent with respect to
 * EXT4_INODE_XXX.  If all is well the printk and BUG_ON will all drop
 * out so it won't cost any extra space in the compiled kernel image.
 * But it's important that these values are the same, since we are
 * using EXT4_INODE_XXX to test for the flag values, but EXT4_XX_FL
 * must be consistent with the values of FS_XXX_FL defined in
 * include/linux/fs.h and the on-disk values found in ext2, ext3, and
 * ext4 filesystems, and of course the values defined in e2fsprogs.
 *
 * It's not paranoia if the Murphy's Law really *is* out to get you.  :-)
 */
static inline void ext4_check_flag_values(void)
{
    CHECK_FLAG_VALUE(SECRM);
    CHECK_FLAG_VALUE(UNRM);
    CHECK_FLAG_VALUE(COMPR);
    CHECK_FLAG_VALUE(SYNC);
    CHECK_FLAG_VALUE(IMMUTABLE);
    CHECK_FLAG_VALUE(APPEND);
    CHECK_FLAG_VALUE(NODUMP);
    CHECK_FLAG_VALUE(NOATIME);
    CHECK_FLAG_VALUE(DIRTY);
    CHECK_FLAG_VALUE(COMPRBLK);
    CHECK_FLAG_VALUE(NOCOMPR);
    CHECK_FLAG_VALUE(ECOMPR);
    CHECK_FLAG_VALUE(INDEX);
    CHECK_FLAG_VALUE(IMAGIC);
    CHECK_FLAG_VALUE(JOURNAL_DATA);
    CHECK_FLAG_VALUE(NOTAIL);
    CHECK_FLAG_VALUE(DIRSYNC);
    CHECK_FLAG_VALUE(TOPDIR);
    CHECK_FLAG_VALUE(HUGE_FILE);
    CHECK_FLAG_VALUE(EXTENTS);
    CHECK_FLAG_VALUE(EA_INODE);
    CHECK_FLAG_VALUE(EOFBLOCKS);
    CHECK_FLAG_VALUE(RESERVED);
}

/* Used to pass group descriptor data when online resize is done */
struct ext4_new_group_input {
    __u32 group;        /* Group number for this data */
    __u64 block_bitmap; /* Absolute block number of block bitmap */
    __u64 inode_bitmap; /* Absolute block number of inode bitmap */
    __u64 inode_table;  /* Absolute block number of inode table start */
    __u32 blocks_count; /* Total number of blocks in this group */
    __u16 reserved_blocks;  /* Number of reserved blocks in this group */
    __u16 unused;
};

#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
struct compat_ext4_new_group_input {
    u32 group;
    compat_u64 block_bitmap;
    compat_u64 inode_bitmap;
    compat_u64 inode_table;
    u32 blocks_count;
    u16 reserved_blocks;
    u16 unused;
};
#endif

/* The struct ext4_new_group_input in kernel space, with free_blocks_count */
struct ext4_new_group_data {
    __u32 group;
    __u64 block_bitmap;
    __u64 inode_bitmap;
    __u64 inode_table;
    __u32 blocks_count;
    __u16 reserved_blocks;
    __u16 unused;
    __u32 free_blocks_count;
};

/* Indexes used to index group tables in ext4_new_group_data */
enum {
    BLOCK_BITMAP = 0,   /* block bitmap */
    INODE_BITMAP,       /* inode bitmap */
    INODE_TABLE,        /* inode tables */
    GROUP_TABLE_COUNT,
};

/*
 * Flags used by ext4_map_blocks()
 */
    /* Allocate any needed blocks and/or convert an unitialized
       extent to be an initialized ext4 */
#define EXT4_GET_BLOCKS_CREATE          0x0001
    /* Request the creation of an unitialized extent */
#define EXT4_GET_BLOCKS_UNINIT_EXT      0x0002
#define EXT4_GET_BLOCKS_CREATE_UNINIT_EXT   (EXT4_GET_BLOCKS_UNINIT_EXT|\
                         EXT4_GET_BLOCKS_CREATE)
    /* Caller is from the delayed allocation writeout path,
       so set the magic i_delalloc_reserve_flag after taking the
       inode allocation semaphore for */
#define EXT4_GET_BLOCKS_DELALLOC_RESERVE    0x0004
    /* caller is from the direct IO path, request to creation of an
    unitialized extents if not allocated, split the uninitialized
    extent if blocks has been preallocated already*/
#define EXT4_GET_BLOCKS_PRE_IO          0x0008
#define EXT4_GET_BLOCKS_CONVERT         0x0010
#define EXT4_GET_BLOCKS_IO_CREATE_EXT       (EXT4_GET_BLOCKS_PRE_IO|\
                     EXT4_GET_BLOCKS_CREATE_UNINIT_EXT)
    /* Convert extent to initialized after IO complete */
#define EXT4_GET_BLOCKS_IO_CONVERT_EXT      (EXT4_GET_BLOCKS_CONVERT|\
                     EXT4_GET_BLOCKS_CREATE_UNINIT_EXT)
    /* Punch out blocks of an extent */
#define EXT4_GET_BLOCKS_PUNCH_OUT_EXT       0x0020
    /* Don't normalize allocation size (used for fallocate) */
#define EXT4_GET_BLOCKS_NO_NORMALIZE        0x0040
    /* Request will not result in inode size update (user for fallocate) */
#define EXT4_GET_BLOCKS_KEEP_SIZE       0x0080
    /* Do not take i_data_sem locking in ext4_map_blocks */
#define EXT4_GET_BLOCKS_NO_LOCK         0x0100

/*
 * Flags used by ext4_free_blocks
 */
#define EXT4_FREE_BLOCKS_METADATA   0x0001
#define EXT4_FREE_BLOCKS_FORGET     0x0002
#define EXT4_FREE_BLOCKS_VALIDATED  0x0004
#define EXT4_FREE_BLOCKS_NO_QUOT_UPDATE 0x0008
#define EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER   0x0010
#define EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER    0x0020

/*
 * Flags used by ext4_discard_partial_page_buffers
 */
#define EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED   0x0001

/*
 * ioctl commands
 */
#define EXT4_IOC_GETFLAGS       FS_IOC_GETFLAGS
#define EXT4_IOC_SETFLAGS       FS_IOC_SETFLAGS
#define EXT4_IOC_GETVERSION     _IOR('f', 3, long)
#define EXT4_IOC_SETVERSION     _IOW('f', 4, long)
#define EXT4_IOC_GETVERSION_OLD     FS_IOC_GETVERSION
#define EXT4_IOC_SETVERSION_OLD     FS_IOC_SETVERSION
#define EXT4_IOC_GETRSVSZ       _IOR('f', 5, long)
#define EXT4_IOC_SETRSVSZ       _IOW('f', 6, long)
#define EXT4_IOC_GROUP_EXTEND       _IOW('f', 7, unsigned long)
#define EXT4_IOC_GROUP_ADD      _IOW('f', 8, struct ext4_new_group_input)
#define EXT4_IOC_MIGRATE        _IO('f', 9)
 /* note ioctl 10 reserved for an early version of the FIEMAP ioctl */
 /* note ioctl 11 reserved for filesystem-independent FIEMAP ioctl */
#define EXT4_IOC_ALLOC_DA_BLKS      _IO('f', 12)
#define EXT4_IOC_MOVE_EXT       _IOWR('f', 15, struct move_extent)
#define EXT4_IOC_RESIZE_FS      _IOW('f', 16, __u64)

#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
/*
 * ioctl commands in 32 bit emulation
 */
#define EXT4_IOC32_GETFLAGS     FS_IOC32_GETFLAGS
#define EXT4_IOC32_SETFLAGS     FS_IOC32_SETFLAGS
#define EXT4_IOC32_GETVERSION       _IOR('f', 3, int)
#define EXT4_IOC32_SETVERSION       _IOW('f', 4, int)
#define EXT4_IOC32_GETRSVSZ     _IOR('f', 5, int)
#define EXT4_IOC32_SETRSVSZ     _IOW('f', 6, int)
#define EXT4_IOC32_GROUP_EXTEND     _IOW('f', 7, unsigned int)
#define EXT4_IOC32_GROUP_ADD        _IOW('f', 8, struct compat_ext4_new_group_input)
#define EXT4_IOC32_GETVERSION_OLD   FS_IOC32_GETVERSION
#define EXT4_IOC32_SETVERSION_OLD   FS_IOC32_SETVERSION
#endif

/* Max physical block we can address w/o extents */
#define EXT4_MAX_BLOCK_FILE_PHYS    0xFFFFFFFF

/*
 * Structure of an inode on the disk
 */
struct ext4_inode {
    __le16  i_mode;     /* File mode */
    __le16  i_uid;      /* Low 16 bits of Owner Uid */
    __le32  i_size_lo;  /* Size in bytes */
    __le32  i_atime;    /* Access time */
    __le32  i_ctime;    /* Inode Change time */
    __le32  i_mtime;    /* Modification time */
    __le32  i_dtime;    /* Deletion Time */
    __le16  i_gid;      /* Low 16 bits of Group Id */
    __le16  i_links_count;  /* Links count */
    __le32  i_blocks_lo;    /* Blocks count */
    __le32  i_flags;    /* File flags */
    union {
        struct {
            __le32  l_i_version;
        } linux1;
        struct {
            __u32  h_i_translator;
        } hurd1;
        struct {
            __u32  m_i_reserved1;
        } masix1;
    } osd1;             /* OS dependent 1 */
    __le32  i_block[EXT4_N_BLOCKS];/* Pointers to blocks */
    __le32  i_generation;   /* File version (for NFS) */
    __le32  i_file_acl_lo;  /* File ACL */
    __le32  i_size_high;
    __le32  i_obso_faddr;   /* Obsoleted fragment address */
    union {
        struct {
            __le16  l_i_blocks_high; /* were l_i_reserved1 */
            __le16  l_i_file_acl_high;
            __le16  l_i_uid_high;   /* these 2 fields */
            __le16  l_i_gid_high;   /* were reserved2[0] */
            __le16  l_i_checksum_lo;/* crc32c(uuid+inum+inode) LE */
            __le16  l_i_reserved;
        } linux2;
        struct {
            __le16  h_i_reserved1;  /* Obsoleted fragment number/size which are removed in ext4 */
            __u16   h_i_mode_high;
            __u16   h_i_uid_high;
            __u16   h_i_gid_high;
            __u32   h_i_author;
        } hurd2;
        struct {
            __le16  h_i_reserved1;  /* Obsoleted fragment number/size which are removed in ext4 */
            __le16  m_i_file_acl_high;
            __u32   m_i_reserved2[2];
        } masix2;
    } osd2;             /* OS dependent 2 */
    __le16  i_extra_isize;
    __le16  i_checksum_hi;  /* crc32c(uuid+inum+inode) BE */
    __le32  i_ctime_extra;  /* extra Change time      (nsec << 2 | epoch) */
    __le32  i_mtime_extra;  /* extra Modification time(nsec << 2 | epoch) */
    __le32  i_atime_extra;  /* extra Access time      (nsec << 2 | epoch) */
    __le32  i_crtime;       /* File Creation time */
    __le32  i_crtime_extra; /* extra FileCreationtime (nsec << 2 | epoch) */
    __le32  i_version_hi;   /* high 32 bits for 64-bit version */
};

struct move_extent {
    __u32 reserved;     /* should be zero */
    __u32 donor_fd;     /* donor file descriptor */
    __u64 orig_start;   /* logical start offset in block for orig */
    __u64 donor_start;  /* logical start offset in block for donor */
    __u64 len;      /* block length to be moved */
    __u64 moved_len;    /* moved block length */
};

#define EXT4_EPOCH_BITS 2
#define EXT4_EPOCH_MASK ((1 << EXT4_EPOCH_BITS) - 1)
#define EXT4_NSEC_MASK  (~0UL << EXT4_EPOCH_BITS)

/*
 * Extended fields will fit into an inode if the filesystem was formatted
 * with large inodes (-I 256 or larger) and there are not currently any EAs
 * consuming all of the available space. For new inodes we always reserve
 * enough space for the kernel's known extended fields, but for inodes
 * created with an old kernel this might not have been the case. None of
 * the extended inode fields is critical for correct filesystem operation.
 * This macro checks if a certain field fits in the inode. Note that
 * inode-size = GOOD_OLD_INODE_SIZE + i_extra_isize
 */
#define EXT4_FITS_IN_INODE(ext4_inode, einode, field)   \
    ((offsetof(typeof(*ext4_inode), field) +    \
      sizeof((ext4_inode)->field))          \
    <= (EXT4_GOOD_OLD_INODE_SIZE +          \
        (einode)->i_extra_isize))           \

static inline __le32 ext4_encode_extra_time(struct timespec *time)
{
       return cpu_to_le32((sizeof(time->tv_sec) > 4 ?
               (time->tv_sec >> 32) & EXT4_EPOCH_MASK : 0) |
                          ((time->tv_nsec << EXT4_EPOCH_BITS) & EXT4_NSEC_MASK));
}

static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
{
       if (sizeof(time->tv_sec) > 4)
           time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK)
                   << 32;
       time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
}

#define EXT4_INODE_SET_XTIME(xtime, inode, raw_inode)                  \
do {                                           \
    (raw_inode)->xtime = cpu_to_le32((inode)->xtime.tv_sec);           \
    if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
        (raw_inode)->xtime ## _extra =                     \
                ext4_encode_extra_time(&(inode)->xtime);       \
} while (0)

#define EXT4_EINODE_SET_XTIME(xtime, einode, raw_inode)                \
do {                                           \
    if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime))              \
        (raw_inode)->xtime = cpu_to_le32((einode)->xtime.tv_sec);      \
    if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra))        \
        (raw_inode)->xtime ## _extra =                     \
                ext4_encode_extra_time(&(einode)->xtime);      \
} while (0)

#define EXT4_INODE_GET_XTIME(xtime, inode, raw_inode)                  \
do {                                           \
    (inode)->xtime.tv_sec = (signed)le32_to_cpu((raw_inode)->xtime);       \
    if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
        ext4_decode_extra_time(&(inode)->xtime,                \
                       raw_inode->xtime ## _extra);        \
    else                                       \
        (inode)->xtime.tv_nsec = 0;                    \
} while (0)

#define EXT4_EINODE_GET_XTIME(xtime, einode, raw_inode)                \
do {                                           \
    if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime))              \
        (einode)->xtime.tv_sec =                       \
            (signed)le32_to_cpu((raw_inode)->xtime);           \
    if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra))        \
        ext4_decode_extra_time(&(einode)->xtime,               \
                       raw_inode->xtime ## _extra);        \
    else                                       \
        (einode)->xtime.tv_nsec = 0;                       \
} while (0)

#define i_disk_version osd1.linux1.l_i_version

#if defined(__KERNEL__) || defined(__linux__)
#define i_reserved1 osd1.linux1.l_i_reserved1
#define i_file_acl_high osd2.linux2.l_i_file_acl_high
#define i_blocks_high   osd2.linux2.l_i_blocks_high
#define i_uid_low   i_uid
#define i_gid_low   i_gid
#define i_uid_high  osd2.linux2.l_i_uid_high
#define i_gid_high  osd2.linux2.l_i_gid_high
#define i_checksum_lo   osd2.linux2.l_i_checksum_lo

#elif defined(__GNU__)

#define i_translator    osd1.hurd1.h_i_translator
#define i_uid_high  osd2.hurd2.h_i_uid_high
#define i_gid_high  osd2.hurd2.h_i_gid_high
#define i_author    osd2.hurd2.h_i_author

#elif defined(__masix__)

#define i_reserved1 osd1.masix1.m_i_reserved1
#define i_file_acl_high osd2.masix2.m_i_file_acl_high
#define i_reserved2 osd2.masix2.m_i_reserved2

#endif /* defined(__KERNEL__) || defined(__linux__) */

/*
 * storage for cached extent
 * If ec_len == 0, then the cache is invalid.
 * If ec_start == 0, then the cache represents a gap (null mapping)
 */
struct ext4_ext_cache {
    ext4_fsblk_t    ec_start;
    ext4_lblk_t ec_block;
    __u32       ec_len; /* must be 32bit to return holes */
};

/*
 * fourth extended file system inode data in memory
 */
struct ext4_inode_info {
    __le32  i_data[15]; /* unconverted */
    __u32   i_dtime;
    ext4_fsblk_t    i_file_acl;

    /*
     * i_block_group is the number of the block group which contains
     * this file's inode.  Constant across the lifetime of the inode,
     * it is ued for making block allocation decisions - we try to
     * place a file's data blocks near its inode block, and new inodes
     * near to their parent directory's inode.
     */
    ext4_group_t    i_block_group;
    ext4_lblk_t i_dir_start_lookup;
#if (BITS_PER_LONG < 64)
    unsigned long   i_state_flags;      /* Dynamic state flags */
#endif
    unsigned long   i_flags;

#ifdef CONFIG_EXT4_FS_XATTR
    /*
     * Extended attributes can be read independently of the main file
     * data. Taking i_mutex even when reading would cause contention
     * between readers of EAs and writers of regular file data, so
     * instead we synchronize on xattr_sem when reading or changing
     * EAs.
     */
    struct rw_semaphore xattr_sem;
#endif

    struct list_head i_orphan;  /* unlinked but open inodes */

    /*
     * i_disksize keeps track of what the inode size is ON DISK, not
     * in memory.  During truncate, i_size is set to the new size by
     * the VFS prior to calling ext4_truncate(), but the filesystem won't
     * set i_disksize to 0 until the truncate is actually under way.
     *
     * The intent is that i_disksize always represents the blocks which
     * are used by this file.  This allows recovery to restart truncate
     * on orphans if we crash during truncate.  We actually write i_disksize
     * into the on-disk inode when writing inodes out, instead of i_size.
     *
     * The only time when i_disksize and i_size may be different is when
     * a truncate is in progress.  The only things which change i_disksize
     * are ext4_get_block (growth) and ext4_truncate (shrinkth).
     */
    loff_t  i_disksize;

    /*
     * i_data_sem is for serialising ext4_truncate() against
     * ext4_getblock().  In the 2.4 ext2 design, great chunks of inode's
     * data tree are chopped off during truncate. We can't do that in
     * ext4 because whenever we perform intermediate commits during
     * truncate, the inode and all the metadata blocks *must* be in a
     * consistent state which allows truncation of the orphans to restart
     * during recovery.  Hence we must fix the get_block-vs-truncate race
     * by other means, so we have i_data_sem.
     */
    struct rw_semaphore i_data_sem;
    struct inode vfs_inode;
    struct jbd2_inode *jinode;

    struct ext4_ext_cache i_cached_extent;
    /*
     * File creation time. Its function is same as that of
     * struct timespec i_{a,c,m}time in the generic inode.
     */
    struct timespec i_crtime;

    /* mballoc */
    struct list_head i_prealloc_list;
    spinlock_t i_prealloc_lock;

    /* ialloc */
    ext4_group_t    i_last_alloc_group;

    /* allocation reservation info for delalloc */
    /* In case of bigalloc, these refer to clusters rather than blocks */
    unsigned int i_reserved_data_blocks;
    unsigned int i_reserved_meta_blocks;
    unsigned int i_allocated_meta_blocks;
    ext4_lblk_t i_da_metadata_calc_last_lblock;
    int i_da_metadata_calc_len;

    /* on-disk additional length */
    __u16 i_extra_isize;

#ifdef CONFIG_QUOTA
    /* quota space reservation, managed internally by quota code */
    qsize_t i_reserved_quota;
#endif

    /* completed IOs that might need unwritten extents handling */
    struct list_head i_completed_io_list;
    spinlock_t i_completed_io_lock;
    atomic_t i_ioend_count; /* Number of outstanding io_end structs */
    atomic_t i_unwritten; /* Nr. of inflight conversions pending */

    spinlock_t i_block_reservation_lock;

    /*
     * Transactions that contain inode's metadata needed to complete
     * fsync and fdatasync, respectively.
     */
    tid_t i_sync_tid;
    tid_t i_datasync_tid;

    /* Precomputed uuid+inum+igen checksum for seeding inode checksums */
    __u32 i_csum_seed;
};

/*
 * File system states
 */
#define EXT4_VALID_FS           0x0001  /* Unmounted cleanly */
#define EXT4_ERROR_FS           0x0002  /* Errors detected */
#define EXT4_ORPHAN_FS          0x0004  /* Orphans being recovered */

/*
 * Misc. filesystem flags
 */
#define EXT2_FLAGS_SIGNED_HASH      0x0001  /* Signed dirhash in use */
#define EXT2_FLAGS_UNSIGNED_HASH    0x0002  /* Unsigned dirhash in use */
#define EXT2_FLAGS_TEST_FILESYS     0x0004  /* to test development code */

/*
 * Mount flags
 */
#define EXT4_MOUNT_GRPID        0x00004 /* Create files with directory's group */
#define EXT4_MOUNT_DEBUG        0x00008 /* Some debugging messages */
#define EXT4_MOUNT_ERRORS_CONT      0x00010 /* Continue on errors */
#define EXT4_MOUNT_ERRORS_RO        0x00020 /* Remount fs ro on errors */
#define EXT4_MOUNT_ERRORS_PANIC     0x00040 /* Panic on errors */
#define EXT4_MOUNT_ERRORS_MASK      0x00070
#define EXT4_MOUNT_MINIX_DF     0x00080 /* Mimics the Minix statfs */
#define EXT4_MOUNT_NOLOAD       0x00100 /* Don't use existing journal*/
#define EXT4_MOUNT_DATA_FLAGS       0x00C00 /* Mode for data writes: */
#define EXT4_MOUNT_JOURNAL_DATA     0x00400 /* Write data to journal */
#define EXT4_MOUNT_ORDERED_DATA     0x00800 /* Flush data before commit */
#define EXT4_MOUNT_WRITEBACK_DATA   0x00C00 /* No data ordering */
#define EXT4_MOUNT_UPDATE_JOURNAL   0x01000 /* Update the journal format */
#define EXT4_MOUNT_NO_UID32     0x02000  /* Disable 32-bit UIDs */
#define EXT4_MOUNT_XATTR_USER       0x04000 /* Extended user attributes */
#define EXT4_MOUNT_POSIX_ACL        0x08000 /* POSIX Access Control Lists */
#define EXT4_MOUNT_NO_AUTO_DA_ALLOC 0x10000 /* No auto delalloc mapping */
#define EXT4_MOUNT_BARRIER      0x20000 /* Use block barriers */
#define EXT4_MOUNT_QUOTA        0x80000 /* Some quota option set */
#define EXT4_MOUNT_USRQUOTA     0x100000 /* "old" user quota */
#define EXT4_MOUNT_GRPQUOTA     0x200000 /* "old" group quota */
#define EXT4_MOUNT_DIOREAD_NOLOCK   0x400000 /* Enable support for dio read nolocking */
#define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */
#define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */
#define EXT4_MOUNT_MBLK_IO_SUBMIT   0x4000000 /* multi-block io submits */
#define EXT4_MOUNT_DELALLOC     0x8000000 /* Delalloc support */
#define EXT4_MOUNT_DATA_ERR_ABORT   0x10000000 /* Abort on file data write */
#define EXT4_MOUNT_BLOCK_VALIDITY   0x20000000 /* Block validity checking */
#define EXT4_MOUNT_DISCARD      0x40000000 /* Issue DISCARD requests */
#define EXT4_MOUNT_INIT_INODE_TABLE 0x80000000 /* Initialize uninitialized itables */

#define EXT4_MOUNT2_EXPLICIT_DELALLOC   0x00000001 /* User explicitly
                              specified delalloc */

#define clear_opt(sb, opt)      EXT4_SB(sb)->s_mount_opt &= \
                        ~EXT4_MOUNT_##opt
#define set_opt(sb, opt)        EXT4_SB(sb)->s_mount_opt |= \
                        EXT4_MOUNT_##opt
#define test_opt(sb, opt)       (EXT4_SB(sb)->s_mount_opt & \
                     EXT4_MOUNT_##opt)

#define clear_opt2(sb, opt)     EXT4_SB(sb)->s_mount_opt2 &= \
                        ~EXT4_MOUNT2_##opt
#define set_opt2(sb, opt)       EXT4_SB(sb)->s_mount_opt2 |= \
                        EXT4_MOUNT2_##opt
#define test_opt2(sb, opt)      (EXT4_SB(sb)->s_mount_opt2 & \
                     EXT4_MOUNT2_##opt)

#define ext4_test_and_set_bit       __test_and_set_bit_le
#define ext4_set_bit            __set_bit_le
#define ext4_set_bit_atomic     ext2_set_bit_atomic
#define ext4_test_and_clear_bit     __test_and_clear_bit_le
#define ext4_clear_bit          __clear_bit_le
#define ext4_clear_bit_atomic       ext2_clear_bit_atomic
#define ext4_test_bit           test_bit_le
#define ext4_find_next_zero_bit     find_next_zero_bit_le
#define ext4_find_next_bit      find_next_bit_le

extern void ext4_set_bits(void *bm, int cur, int len);

/*
 * Maximal mount counts between two filesystem checks
 */
#define EXT4_DFL_MAX_MNT_COUNT      20  /* Allow 20 mounts */
#define EXT4_DFL_CHECKINTERVAL      0   /* Don't use interval check */

/*
 * Behaviour when detecting errors
 */
#define EXT4_ERRORS_CONTINUE        1   /* Continue execution */
#define EXT4_ERRORS_RO          2   /* Remount fs read-only */
#define EXT4_ERRORS_PANIC       3   /* Panic */
#define EXT4_ERRORS_DEFAULT     EXT4_ERRORS_CONTINUE

/* Metadata checksum algorithm codes */
#define EXT4_CRC32C_CHKSUM      1

/*
 * Structure of the super block
 */
struct ext4_super_block {
/*00*/  __le32  s_inodes_count;     /* Inodes count */
    __le32  s_blocks_count_lo;  /* Blocks count */
    __le32  s_r_blocks_count_lo;    /* Reserved blocks count */
    __le32  s_free_blocks_count_lo; /* Free blocks count */
/*10*/  __le32  s_free_inodes_count;    /* Free inodes count */
    __le32  s_first_data_block; /* First Data Block */
    __le32  s_log_block_size;   /* Block size */
    __le32  s_log_cluster_size; /* Allocation cluster size */
/*20*/  __le32  s_blocks_per_group; /* # Blocks per group */
    __le32  s_clusters_per_group;   /* # Clusters per group */
    __le32  s_inodes_per_group; /* # Inodes per group */
    __le32  s_mtime;        /* Mount time */
/*30*/  __le32  s_wtime;        /* Write time */
    __le16  s_mnt_count;        /* Mount count */
    __le16  s_max_mnt_count;    /* Maximal mount count */
    __le16  s_magic;        /* Magic signature */
    __le16  s_state;        /* File system state */
    __le16  s_errors;       /* Behaviour when detecting errors */
    __le16  s_minor_rev_level;  /* minor revision level */
/*40*/  __le32  s_lastcheck;        /* time of last check */
    __le32  s_checkinterval;    /* max. time between checks */
    __le32  s_creator_os;       /* OS */
    __le32  s_rev_level;        /* Revision level */
/*50*/  __le16  s_def_resuid;       /* Default uid for reserved blocks */
    __le16  s_def_resgid;       /* Default gid for reserved blocks */
    /*
     * These fields are for EXT4_DYNAMIC_REV superblocks only.
     *
     * Note: the difference between the compatible feature set and
     * the incompatible feature set is that 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.
     *
     * e2fsck's requirements are more strict; if it doesn't know
     * about a feature in either the compatible or incompatible
     * feature set, it must abort and not try to meddle with
     * things it doesn't understand...
     */
    __le32  s_first_ino;        /* First non-reserved inode */
    __le16  s_inode_size;       /* size of inode structure */
    __le16  s_block_group_nr;   /* block group # of this superblock */
    __le32  s_feature_compat;   /* compatible feature set */
/*60*/  __le32  s_feature_incompat; /* incompatible feature set */
    __le32  s_feature_ro_compat;    /* readonly-compatible feature set */
/*68*/  __u8    s_uuid[16];     /* 128-bit uuid for volume */
/*78*/  char    s_volume_name[16];  /* volume name */
/*88*/  char    s_last_mounted[64]; /* directory where last mounted */
/*C8*/  __le32  s_algorithm_usage_bitmap; /* For compression */
    /*
     * Performance hints.  Directory preallocation should only
     * happen if the EXT4_FEATURE_COMPAT_DIR_PREALLOC flag is on.
     */
    __u8    s_prealloc_blocks;  /* Nr of blocks to try to preallocate*/
    __u8    s_prealloc_dir_blocks;  /* Nr to preallocate for dirs */
    __le16  s_reserved_gdt_blocks;  /* Per group desc for online growth */
    /*
     * Journaling support valid if EXT4_FEATURE_COMPAT_HAS_JOURNAL set.
     */
/*D0*/  __u8    s_journal_uuid[16]; /* uuid of journal superblock */
/*E0*/  __le32  s_journal_inum;     /* inode number of journal file */
    __le32  s_journal_dev;      /* device number of journal file */
    __le32  s_last_orphan;      /* start of list of inodes to delete */
    __le32  s_hash_seed[4];     /* HTREE hash seed */
    __u8    s_def_hash_version; /* Default hash version to use */
    __u8    s_jnl_backup_type;
    __le16  s_desc_size;        /* size of group descriptor */
/*100*/ __le32  s_default_mount_opts;
    __le32  s_first_meta_bg;    /* First metablock block group */
    __le32  s_mkfs_time;        /* When the filesystem was created */
    __le32  s_jnl_blocks[17];   /* Backup of the journal inode */
    /* 64bit support valid if EXT4_FEATURE_COMPAT_64BIT */
/*150*/ __le32  s_blocks_count_hi;  /* Blocks count */
    __le32  s_r_blocks_count_hi;    /* Reserved blocks count */
    __le32  s_free_blocks_count_hi; /* Free blocks count */
    __le16  s_min_extra_isize;  /* All inodes have at least # bytes */
    __le16  s_want_extra_isize;     /* New inodes should reserve # bytes */
    __le32  s_flags;        /* Miscellaneous flags */
    __le16  s_raid_stride;      /* RAID stride */
    __le16  s_mmp_update_interval;  /* # seconds to wait in MMP checking */
    __le64  s_mmp_block;            /* Block for multi-mount protection */
    __le32  s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/
    __u8    s_log_groups_per_flex;  /* FLEX_BG group size */
    __u8    s_checksum_type;    /* metadata checksum algorithm used */
    __le16  s_reserved_pad;
    __le64  s_kbytes_written;   /* nr of lifetime kilobytes written */
    __le32  s_snapshot_inum;    /* Inode number of active snapshot */
    __le32  s_snapshot_id;      /* sequential ID of active snapshot */
    __le64  s_snapshot_r_blocks_count; /* reserved blocks for active
                          snapshot's future use */
    __le32  s_snapshot_list;    /* inode number of the head of the
                       on-disk snapshot list */
#define EXT4_S_ERR_START offsetof(struct ext4_super_block, s_error_count)
    __le32  s_error_count;      /* number of fs errors */
    __le32  s_first_error_time; /* first time an error happened */
    __le32  s_first_error_ino;  /* inode involved in first error */
    __le64  s_first_error_block;    /* block involved of first error */
    __u8    s_first_error_func[32]; /* function where the error happened */
    __le32  s_first_error_line; /* line number where error happened */
    __le32  s_last_error_time;  /* most recent time of an error */
    __le32  s_last_error_ino;   /* inode involved in last error */
    __le32  s_last_error_line;  /* line number where error happened */
    __le64  s_last_error_block; /* block involved of last error */
    __u8    s_last_error_func[32];  /* function where the error happened */
#define EXT4_S_ERR_END offsetof(struct ext4_super_block, s_mount_opts)
    __u8    s_mount_opts[64];
    __le32  s_usr_quota_inum;   /* inode for tracking user quota */
    __le32  s_grp_quota_inum;   /* inode for tracking group quota */
    __le32  s_overhead_clusters;    /* overhead blocks/clusters in fs */
    __le32  s_reserved[108];    /* Padding to the end of the block */
    __le32  s_checksum;     /* crc32c(superblock) */
};

#define EXT4_S_ERR_LEN (EXT4_S_ERR_END - EXT4_S_ERR_START)

#ifdef __KERNEL__

/*
 * run-time mount flags
 */
#define EXT4_MF_MNTDIR_SAMPLED  0x0001
#define EXT4_MF_FS_ABORTED  0x0002  /* Fatal error detected */

/*
 * fourth extended-fs super-block data in memory
 */
struct ext4_sb_info {
    unsigned long s_desc_size;  /* Size of a group descriptor in bytes */
    unsigned long s_inodes_per_block;/* Number of inodes per block */
    unsigned long s_blocks_per_group;/* Number of blocks in a group */
    unsigned long s_clusters_per_group; /* Number of clusters in a group */
    unsigned long s_inodes_per_group;/* Number of inodes in a group */
    unsigned long s_itb_per_group;  /* Number of inode table blocks per group */
    unsigned long s_gdb_count;  /* Number of group descriptor blocks */
    unsigned long s_desc_per_block; /* Number of group descriptors per block */
    ext4_group_t s_groups_count;    /* Number of groups in the fs */
    ext4_group_t s_blockfile_groups;/* Groups acceptable for non-extent files */
    unsigned long s_overhead;  /* # of fs overhead clusters */
    unsigned int s_cluster_ratio;   /* Number of blocks per cluster */
    unsigned int s_cluster_bits;    /* log2 of s_cluster_ratio */
    loff_t s_bitmap_maxbytes;   /* max bytes for bitmap files */
    struct buffer_head * s_sbh; /* Buffer containing the super block */
    struct ext4_super_block *s_es;  /* Pointer to the super block in the buffer */
    struct buffer_head **s_group_desc;
    unsigned int s_mount_opt;
    unsigned int s_mount_opt2;
    unsigned int s_mount_flags;
    unsigned int s_def_mount_opt;
    ext4_fsblk_t s_sb_block;
    kuid_t s_resuid;
    kgid_t s_resgid;
    unsigned short s_mount_state;
    unsigned short s_pad;
    int s_addr_per_block_bits;
    int s_desc_per_block_bits;
    int s_inode_size;
    int s_first_ino;
    unsigned int s_inode_readahead_blks;
    unsigned int s_inode_goal;
    spinlock_t s_next_gen_lock;
    u32 s_next_generation;
    u32 s_hash_seed[4];
    int s_def_hash_version;
    int s_hash_unsigned;    /* 3 if hash should be signed, 0 if not */
    struct percpu_counter s_freeclusters_counter;
    struct percpu_counter s_freeinodes_counter;
    struct percpu_counter s_dirs_counter;
    struct percpu_counter s_dirtyclusters_counter;
    struct blockgroup_lock *s_blockgroup_lock;
    struct proc_dir_entry *s_proc;
    struct kobject s_kobj;
    struct completion s_kobj_unregister;
    struct super_block *s_sb;

    /* Journaling */
    struct journal_s *s_journal;
    struct list_head s_orphan;
    struct mutex s_orphan_lock;
    unsigned long s_resize_flags;       /* Flags indicating if there
                           is a resizer */
    unsigned long s_commit_interval;
    u32 s_max_batch_time;
    u32 s_min_batch_time;
    struct block_device *journal_bdev;
#ifdef CONFIG_QUOTA
    char *s_qf_names[MAXQUOTAS];        /* Names of quota files with journalled quota */
    int s_jquota_fmt;           /* Format of quota to use */
#endif
    unsigned int s_want_extra_isize; /* New inodes should reserve # bytes */
    struct rb_root system_blks;

#ifdef EXTENTS_STATS
    /* ext4 extents stats */
    unsigned long s_ext_min;
    unsigned long s_ext_max;
    unsigned long s_depth_max;
    spinlock_t s_ext_stats_lock;
    unsigned long s_ext_blocks;
    unsigned long s_ext_extents;
#endif

    /* for buddy allocator */
    struct ext4_group_info ***s_group_info;
    struct inode *s_buddy_cache;
    spinlock_t s_md_lock;
    unsigned short *s_mb_offsets;
    unsigned int *s_mb_maxs;
    unsigned int s_group_info_size;

    /* tunables */
    unsigned long s_stripe;
    unsigned int s_mb_stream_request;
    unsigned int s_mb_max_to_scan;
    unsigned int s_mb_min_to_scan;
    unsigned int s_mb_stats;
    unsigned int s_mb_order2_reqs;
    unsigned int s_mb_group_prealloc;
    unsigned int s_max_writeback_mb_bump;
    unsigned int s_max_dir_size_kb;
    /* where last allocation was done - for stream allocation */
    unsigned long s_mb_last_group;
    unsigned long s_mb_last_start;

    /* stats for buddy allocator */
    atomic_t s_bal_reqs;    /* number of reqs with len > 1 */
    atomic_t s_bal_success; /* we found long enough chunks */
    atomic_t s_bal_allocated;   /* in blocks */
    atomic_t s_bal_ex_scanned;  /* total extents scanned */
    atomic_t s_bal_goals;   /* goal hits */
    atomic_t s_bal_breaks;  /* too long searches */
    atomic_t s_bal_2orders; /* 2^order hits */
    spinlock_t s_bal_lock;
    unsigned long s_mb_buddies_generated;
    unsigned long long s_mb_generation_time;
    atomic_t s_mb_lost_chunks;
    atomic_t s_mb_preallocated;
    atomic_t s_mb_discarded;
    atomic_t s_lock_busy;

    /* locality groups */
    struct ext4_locality_group __percpu *s_locality_groups;

    /* for write statistics */
    unsigned long s_sectors_written_start;
    u64 s_kbytes_written;

    /* the size of zero-out chunk */
    unsigned int s_extent_max_zeroout_kb;

    unsigned int s_log_groups_per_flex;
    struct flex_groups *s_flex_groups;
    ext4_group_t s_flex_groups_allocated;

    /* workqueue for dio unwritten */
    struct workqueue_struct *dio_unwritten_wq;

    /* timer for periodic error stats printing */
    struct timer_list s_err_report;

    /* Lazy inode table initialization info */
    struct ext4_li_request *s_li_request;
    /* Wait multiplier for lazy initialization thread */
    unsigned int s_li_wait_mult;

    /* Kernel thread for multiple mount protection */
    struct task_struct *s_mmp_tsk;

    /* record the last minlen when FITRIM is called. */
    atomic_t s_last_trim_minblks;

    /* Reference to checksum algorithm driver via cryptoapi */
    struct crypto_shash *s_chksum_driver;

    /* Precomputed FS UUID checksum for seeding other checksums */
    __u32 s_csum_seed;
};

static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
{
    return sb->s_fs_info;
}
static inline struct ext4_inode_info *EXT4_I(struct inode *inode)
{
    return container_of(inode, struct ext4_inode_info, vfs_inode);
}

static inline struct timespec ext4_current_time(struct inode *inode)
{
    return (inode->i_sb->s_time_gran < NSEC_PER_SEC) ?
        current_fs_time(inode->i_sb) : CURRENT_TIME_SEC;
}

static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
{
    return ino == EXT4_ROOT_INO ||
        ino == EXT4_USR_QUOTA_INO ||
        ino == EXT4_GRP_QUOTA_INO ||
        ino == EXT4_JOURNAL_INO ||
        ino == EXT4_RESIZE_INO ||
        (ino >= EXT4_FIRST_INO(sb) &&
         ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));
}

static inline void ext4_set_io_unwritten_flag(struct inode *inode,
                          struct ext4_io_end *io_end)
{
    if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
        io_end->flag |= EXT4_IO_END_UNWRITTEN;
        atomic_inc(&EXT4_I(inode)->i_unwritten);
    }
}

static inline ext4_io_end_t *ext4_inode_aio(struct inode *inode)
{
    return inode->i_private;
}

static inline void ext4_inode_aio_set(struct inode *inode, ext4_io_end_t *io)
{
    inode->i_private = io;
}

/*
 * Inode dynamic state flags
 */
enum {
    EXT4_STATE_JDATA,       /* journaled data exists */
    EXT4_STATE_NEW,         /* inode is newly created */
    EXT4_STATE_XATTR,       /* has in-inode xattrs */
    EXT4_STATE_NO_EXPAND,       /* No space for expansion */
    EXT4_STATE_DA_ALLOC_CLOSE,  /* Alloc DA blks on close */
    EXT4_STATE_EXT_MIGRATE,     /* Inode is migrating */
    EXT4_STATE_DIO_UNWRITTEN,   /* need convert on dio done*/
    EXT4_STATE_NEWENTRY,        /* File just added to dir */
    EXT4_STATE_DELALLOC_RESERVED,   /* blks already reserved for delalloc */
    EXT4_STATE_DIOREAD_LOCK,    /* Disable support for dio read
                       nolocking */
};

#define EXT4_INODE_BIT_FNS(name, field, offset)             \
static inline int ext4_test_inode_##name(struct inode *inode, int bit)  \
{                                   \
    return test_bit(bit + (offset), &EXT4_I(inode)->i_##field); \
}                                   \
static inline void ext4_set_inode_##name(struct inode *inode, int bit)  \
{                                   \
    set_bit(bit + (offset), &EXT4_I(inode)->i_##field);     \
}                                   \
static inline void ext4_clear_inode_##name(struct inode *inode, int bit) \
{                                   \
    clear_bit(bit + (offset), &EXT4_I(inode)->i_##field);       \
}

EXT4_INODE_BIT_FNS(flag, flags, 0)
#if (BITS_PER_LONG < 64)
EXT4_INODE_BIT_FNS(state, state_flags, 0)

static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
{
    (ei)->i_state_flags = 0;
}
#else
EXT4_INODE_BIT_FNS(state, flags, 32)

static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
{
    /* We depend on the fact that callers will set i_flags */
}
#endif
#else
/* Assume that user mode programs are passing in an ext4fs superblock, not
 * a kernel struct super_block.  This will allow us to call the feature-test
 * macros from user land. */
#define EXT4_SB(sb) (sb)
#endif

#define NEXT_ORPHAN(inode) EXT4_I(inode)->i_dtime

/*
 * Codes for operating systems
 */
#define EXT4_OS_LINUX       0
#define EXT4_OS_HURD        1
#define EXT4_OS_MASIX       2
#define EXT4_OS_FREEBSD     3
#define EXT4_OS_LITES       4

/*
 * Revision levels
 */
#define EXT4_GOOD_OLD_REV   0   /* The good old (original) format */
#define EXT4_DYNAMIC_REV    1   /* V2 format w/ dynamic inode sizes */

#define EXT4_CURRENT_REV    EXT4_GOOD_OLD_REV
#define EXT4_MAX_SUPP_REV   EXT4_DYNAMIC_REV

#define EXT4_GOOD_OLD_INODE_SIZE 128

/*
 * Feature set definitions
 */

#define EXT4_HAS_COMPAT_FEATURE(sb,mask)            \
    ((EXT4_SB(sb)->s_es->s_feature_compat & cpu_to_le32(mask)) != 0)
#define EXT4_HAS_RO_COMPAT_FEATURE(sb,mask)         \
    ((EXT4_SB(sb)->s_es->s_feature_ro_compat & cpu_to_le32(mask)) != 0)
#define EXT4_HAS_INCOMPAT_FEATURE(sb,mask)          \
    ((EXT4_SB(sb)->s_es->s_feature_incompat & cpu_to_le32(mask)) != 0)
#define EXT4_SET_COMPAT_FEATURE(sb,mask)            \
    EXT4_SB(sb)->s_es->s_feature_compat |= cpu_to_le32(mask)
#define EXT4_SET_RO_COMPAT_FEATURE(sb,mask)         \
    EXT4_SB(sb)->s_es->s_feature_ro_compat |= cpu_to_le32(mask)
#define EXT4_SET_INCOMPAT_FEATURE(sb,mask)          \
    EXT4_SB(sb)->s_es->s_feature_incompat |= cpu_to_le32(mask)
#define EXT4_CLEAR_COMPAT_FEATURE(sb,mask)          \
    EXT4_SB(sb)->s_es->s_feature_compat &= ~cpu_to_le32(mask)
#define EXT4_CLEAR_RO_COMPAT_FEATURE(sb,mask)           \
    EXT4_SB(sb)->s_es->s_feature_ro_compat &= ~cpu_to_le32(mask)
#define EXT4_CLEAR_INCOMPAT_FEATURE(sb,mask)            \
    EXT4_SB(sb)->s_es->s_feature_incompat &= ~cpu_to_le32(mask)

#define EXT4_FEATURE_COMPAT_DIR_PREALLOC    0x0001
#define EXT4_FEATURE_COMPAT_IMAGIC_INODES   0x0002
#define EXT4_FEATURE_COMPAT_HAS_JOURNAL     0x0004
#define EXT4_FEATURE_COMPAT_EXT_ATTR        0x0008
#define EXT4_FEATURE_COMPAT_RESIZE_INODE    0x0010
#define EXT4_FEATURE_COMPAT_DIR_INDEX       0x0020

#define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
#define EXT4_FEATURE_RO_COMPAT_LARGE_FILE   0x0002
#define EXT4_FEATURE_RO_COMPAT_BTREE_DIR    0x0004
#define EXT4_FEATURE_RO_COMPAT_HUGE_FILE        0x0008
#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM     0x0010
#define EXT4_FEATURE_RO_COMPAT_DIR_NLINK    0x0020
#define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE  0x0040
#define EXT4_FEATURE_RO_COMPAT_QUOTA        0x0100
#define EXT4_FEATURE_RO_COMPAT_BIGALLOC     0x0200
/*
 * METADATA_CSUM also enables group descriptor checksums (GDT_CSUM).  When
 * METADATA_CSUM is set, group descriptor checksums use the same algorithm as
 * all other data structures' checksums.  However, the METADATA_CSUM and
 * GDT_CSUM bits are mutually exclusive.
 */
#define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM    0x0400

#define EXT4_FEATURE_INCOMPAT_COMPRESSION   0x0001
#define EXT4_FEATURE_INCOMPAT_FILETYPE      0x0002
#define EXT4_FEATURE_INCOMPAT_RECOVER       0x0004 /* Needs recovery */
#define EXT4_FEATURE_INCOMPAT_JOURNAL_DEV   0x0008 /* Journal device */
#define EXT4_FEATURE_INCOMPAT_META_BG       0x0010
#define EXT4_FEATURE_INCOMPAT_EXTENTS       0x0040 /* extents support */
#define EXT4_FEATURE_INCOMPAT_64BIT     0x0080
#define EXT4_FEATURE_INCOMPAT_MMP               0x0100
#define EXT4_FEATURE_INCOMPAT_FLEX_BG       0x0200
#define EXT4_FEATURE_INCOMPAT_EA_INODE      0x0400 /* EA in inode */
#define EXT4_FEATURE_INCOMPAT_DIRDATA       0x1000 /* data in dirent */
#define EXT4_FEATURE_INCOMPAT_BG_USE_META_CSUM  0x2000 /* use crc32c for bg */
#define EXT4_FEATURE_INCOMPAT_LARGEDIR      0x4000 /* >2GB or 3-lvl htree */
#define EXT4_FEATURE_INCOMPAT_INLINEDATA    0x8000 /* data in inode */

#define EXT2_FEATURE_COMPAT_SUPP    EXT4_FEATURE_COMPAT_EXT_ATTR
#define EXT2_FEATURE_INCOMPAT_SUPP  (EXT4_FEATURE_INCOMPAT_FILETYPE| \
                     EXT4_FEATURE_INCOMPAT_META_BG)
#define EXT2_FEATURE_RO_COMPAT_SUPP (EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                     EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
                     EXT4_FEATURE_RO_COMPAT_BTREE_DIR)

#define EXT3_FEATURE_COMPAT_SUPP    EXT4_FEATURE_COMPAT_EXT_ATTR
#define EXT3_FEATURE_INCOMPAT_SUPP  (EXT4_FEATURE_INCOMPAT_FILETYPE| \
                     EXT4_FEATURE_INCOMPAT_RECOVER| \
                     EXT4_FEATURE_INCOMPAT_META_BG)
#define EXT3_FEATURE_RO_COMPAT_SUPP (EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                     EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
                     EXT4_FEATURE_RO_COMPAT_BTREE_DIR)

#define EXT4_FEATURE_COMPAT_SUPP    EXT2_FEATURE_COMPAT_EXT_ATTR
#define EXT4_FEATURE_INCOMPAT_SUPP  (EXT4_FEATURE_INCOMPAT_FILETYPE| \
                     EXT4_FEATURE_INCOMPAT_RECOVER| \
                     EXT4_FEATURE_INCOMPAT_META_BG| \
                     EXT4_FEATURE_INCOMPAT_EXTENTS| \
                     EXT4_FEATURE_INCOMPAT_64BIT| \
                     EXT4_FEATURE_INCOMPAT_FLEX_BG| \
                     EXT4_FEATURE_INCOMPAT_MMP)
#define EXT4_FEATURE_RO_COMPAT_SUPP (EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                     EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
                     EXT4_FEATURE_RO_COMPAT_GDT_CSUM| \
                     EXT4_FEATURE_RO_COMPAT_DIR_NLINK | \
                     EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE | \
                     EXT4_FEATURE_RO_COMPAT_BTREE_DIR |\
                     EXT4_FEATURE_RO_COMPAT_HUGE_FILE |\
                     EXT4_FEATURE_RO_COMPAT_BIGALLOC |\
                     EXT4_FEATURE_RO_COMPAT_METADATA_CSUM|\
                     EXT4_FEATURE_RO_COMPAT_QUOTA)

/*
 * Default values for user and/or group using reserved blocks
 */
#define EXT4_DEF_RESUID     0
#define EXT4_DEF_RESGID     0

#define EXT4_DEF_INODE_READAHEAD_BLKS   32

/*
 * Default mount options
 */
#define EXT4_DEFM_DEBUG     0x0001
#define EXT4_DEFM_BSDGROUPS 0x0002
#define EXT4_DEFM_XATTR_USER    0x0004
#define EXT4_DEFM_ACL       0x0008
#define EXT4_DEFM_UID16     0x0010
#define EXT4_DEFM_JMODE     0x0060
#define EXT4_DEFM_JMODE_DATA    0x0020
#define EXT4_DEFM_JMODE_ORDERED 0x0040
#define EXT4_DEFM_JMODE_WBACK   0x0060
#define EXT4_DEFM_NOBARRIER 0x0100
#define EXT4_DEFM_BLOCK_VALIDITY 0x0200
#define EXT4_DEFM_DISCARD   0x0400
#define EXT4_DEFM_NODELALLOC    0x0800

/*
 * Default journal batch times
 */
#define EXT4_DEF_MIN_BATCH_TIME 0
#define EXT4_DEF_MAX_BATCH_TIME 15000 /* 15ms */

/*
 * Minimum number of groups in a flexgroup before we separate out
 * directories into the first block group of a flexgroup
 */
#define EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME 4

/*
 * Structure of a directory entry
 */
#define EXT4_NAME_LEN 255

struct ext4_dir_entry {
    __le32  inode;          /* Inode number */
    __le16  rec_len;        /* Directory entry length */
    __le16  name_len;       /* Name length */
    char    name[EXT4_NAME_LEN];    /* File name */
};

/*
 * The new version of the directory entry.  Since EXT4 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 ext4_dir_entry_2 {
    __le32  inode;          /* Inode number */
    __le16  rec_len;        /* Directory entry length */
    __u8    name_len;       /* Name length */
    __u8    file_type;
    char    name[EXT4_NAME_LEN];    /* File name */
};

/*
 * This is a bogus directory entry at the end of each leaf block that
 * records checksums.
 */
struct ext4_dir_entry_tail {
    __le32  det_reserved_zero1; /* Pretend to be unused */
    __le16  det_rec_len;        /* 12 */
    __u8    det_reserved_zero2; /* Zero name length */
    __u8    det_reserved_ft;    /* 0xDE, fake file type */
    __le32  det_checksum;       /* crc32c(uuid+inum+dirblock) */
};

/*
 * Ext4 directory file types.  Only the low 3 bits are used.  The
 * other bits are reserved for now.
 */
#define EXT4_FT_UNKNOWN     0
#define EXT4_FT_REG_FILE    1
#define EXT4_FT_DIR     2
#define EXT4_FT_CHRDEV      3
#define EXT4_FT_BLKDEV      4
#define EXT4_FT_FIFO        5
#define EXT4_FT_SOCK        6
#define EXT4_FT_SYMLINK     7

#define EXT4_FT_MAX     8

#define EXT4_FT_DIR_CSUM    0xDE

/*
 * EXT4_DIR_PAD defines the directory entries boundaries
 *
 * NOTE: It must be a multiple of 4
 */
#define EXT4_DIR_PAD            4
#define EXT4_DIR_ROUND          (EXT4_DIR_PAD - 1)
#define EXT4_DIR_REC_LEN(name_len)  (((name_len) + 8 + EXT4_DIR_ROUND) & \
                     ~EXT4_DIR_ROUND)
#define EXT4_MAX_REC_LEN        ((1<<16)-1)

/*
 * If we ever get support for fs block sizes > page_size, we'll need
 * to remove the #if statements in the next two functions...
 */
static inline unsigned int
ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize)
{
    unsigned len = le16_to_cpu(dlen);

#if (PAGE_CACHE_SIZE >= 65536)
    if (len == EXT4_MAX_REC_LEN || len == 0)
        return blocksize;
    return (len & 65532) | ((len & 3) << 16);
#else
    return len;
#endif
}

static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)
{
    if ((len > blocksize) || (blocksize > (1 << 18)) || (len & 3))
        BUG();
#if (PAGE_CACHE_SIZE >= 65536)
    if (len < 65536)
        return cpu_to_le16(len);
    if (len == blocksize) {
        if (blocksize == 65536)
            return cpu_to_le16(EXT4_MAX_REC_LEN);
        else
            return cpu_to_le16(0);
    }
    return cpu_to_le16((len & 65532) | ((len >> 16) & 3));
#else
    return cpu_to_le16(len);
#endif
}

/*
 * Hash Tree Directory indexing
 * (c) Daniel Phillips, 2001
 */

#define is_dx(dir) (EXT4_HAS_COMPAT_FEATURE(dir->i_sb, \
                      EXT4_FEATURE_COMPAT_DIR_INDEX) && \
            ext4_test_inode_flag((dir), EXT4_INODE_INDEX))
#define EXT4_DIR_LINK_MAX(dir) (!is_dx(dir) && (dir)->i_nlink >= EXT4_LINK_MAX)
#define EXT4_DIR_LINK_EMPTY(dir) ((dir)->i_nlink == 2 || (dir)->i_nlink == 1)

/* Legal values for the dx_root hash_version field: */

#define DX_HASH_LEGACY      0
#define DX_HASH_HALF_MD4    1
#define DX_HASH_TEA     2
#define DX_HASH_LEGACY_UNSIGNED 3
#define DX_HASH_HALF_MD4_UNSIGNED   4
#define DX_HASH_TEA_UNSIGNED        5

static inline u32 ext4_chksum(struct ext4_sb_info *sbi, u32 crc,
                  const void *address, unsigned int length)
{
    struct {
        struct shash_desc shash;
        char ctx[4];
    } desc;
    int err;

    BUG_ON(crypto_shash_descsize(sbi->s_chksum_driver)!=sizeof(desc.ctx));

    desc.shash.tfm = sbi->s_chksum_driver;
    desc.shash.flags = 0;
    *(u32 *)desc.ctx = crc;

    err = crypto_shash_update(&desc.shash, address, length);
    BUG_ON(err);

    return *(u32 *)desc.ctx;
}

#ifdef __KERNEL__

/* hash info structure used by the directory hash */
struct dx_hash_info
{
    u32     hash;
    u32     minor_hash;
    int     hash_version;
    u32     *seed;
};


/* 32 and 64 bit signed EOF for dx directories */
#define EXT4_HTREE_EOF_32BIT   ((1UL  << (32 - 1)) - 1)
#define EXT4_HTREE_EOF_64BIT   ((1ULL << (64 - 1)) - 1)


/*
 * Control parameters used by ext4_htree_next_block
 */
#define HASH_NB_ALWAYS      1


/*
 * Describe an inode's exact location on disk and in memory
 */
struct ext4_iloc
{
    struct buffer_head *bh;
    unsigned long offset;
    ext4_group_t block_group;
};

static inline struct ext4_inode *ext4_raw_inode(struct ext4_iloc *iloc)
{
    return (struct ext4_inode *) (iloc->bh->b_data + iloc->offset);
}

/*
 * This structure is stuffed into the struct file's private_data field
 * for directories.  It is where we put information so that we can do
 * readdir operations in hash tree order.
 */
struct dir_private_info {
    struct rb_root  root;
    struct rb_node  *curr_node;
    struct fname    *extra_fname;
    loff_t      last_pos;
    __u32       curr_hash;
    __u32       curr_minor_hash;
    __u32       next_hash;
};

/* calculate the first block number of the group */
static inline ext4_fsblk_t
ext4_group_first_block_no(struct super_block *sb, ext4_group_t group_no)
{
    return group_no * (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
        le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
}

/*
 * Special error return code only used by dx_probe() and its callers.
 */
#define ERR_BAD_DX_DIR  -75000

void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
            ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp);

/*
 * Timeout and state flag for lazy initialization inode thread.
 */
#define EXT4_DEF_LI_WAIT_MULT           10
#define EXT4_DEF_LI_MAX_START_DELAY     5
#define EXT4_LAZYINIT_QUIT          0x0001
#define EXT4_LAZYINIT_RUNNING           0x0002

/*
 * Lazy inode table initialization info
 */
struct ext4_lazy_init {
    unsigned long       li_state;
    struct list_head    li_request_list;
    struct mutex        li_list_mtx;
};

struct ext4_li_request {
    struct super_block  *lr_super;
    struct ext4_sb_info *lr_sbi;
    ext4_group_t        lr_next_group;
    struct list_head    lr_request;
    unsigned long       lr_next_sched;
    unsigned long       lr_timeout;
};

struct ext4_features {
    struct kobject f_kobj;
    struct completion f_kobj_unregister;
};

/*
 * This structure will be used for multiple mount protection. It will be
 * written into the block number saved in the s_mmp_block field in the
 * superblock. Programs that check MMP should assume that if
 * SEQ_FSCK (or any unknown code above SEQ_MAX) is present then it is NOT safe
 * to use the filesystem, regardless of how old the timestamp is.
 */
#define EXT4_MMP_MAGIC     0x004D4D50U /* ASCII for MMP */
#define EXT4_MMP_SEQ_CLEAN 0xFF4D4D50U /* mmp_seq value for clean unmount */
#define EXT4_MMP_SEQ_FSCK  0xE24D4D50U /* mmp_seq value when being fscked */
#define EXT4_MMP_SEQ_MAX   0xE24D4D4FU /* maximum valid mmp_seq value */

struct mmp_struct {
    __le32  mmp_magic;      /* Magic number for MMP */
    __le32  mmp_seq;        /* Sequence no. updated periodically */

    /*
     * mmp_time, mmp_nodename & mmp_bdevname are only used for information
     * purposes and do not affect the correctness of the algorithm
     */
    __le64  mmp_time;       /* Time last updated */
    char    mmp_nodename[64];   /* Node which last updated MMP block */
    char    mmp_bdevname[32];   /* Bdev which last updated MMP block */

    /*
     * mmp_check_interval is used to verify if the MMP block has been
     * updated on the block device. The value is updated based on the
     * maximum time to write the MMP block during an update cycle.
     */
    __le16  mmp_check_interval;

    __le16  mmp_pad1;
    __le32  mmp_pad2[226];
    __le32  mmp_checksum;       /* crc32c(uuid+mmp_block) */
};

/* arguments passed to the mmp thread */
struct mmpd_data {
    struct buffer_head *bh; /* bh from initial read_mmp_block() */
    struct super_block *sb;  /* super block of the fs */
};

/*
 * Check interval multiplier
 * The MMP block is written every update interval and initially checked every
 * update interval x the multiplier (the value is then adapted based on the
 * write latency). The reason is that writes can be delayed under load and we
 * don't want readers to incorrectly assume that the filesystem is no longer
 * in use.
 */
#define EXT4_MMP_CHECK_MULT     2UL

/*
 * Minimum interval for MMP checking in seconds.
 */
#define EXT4_MMP_MIN_CHECK_INTERVAL 5UL

/*
 * Maximum interval for MMP checking in seconds.
 */
#define EXT4_MMP_MAX_CHECK_INTERVAL 300UL

/*
 * Function prototypes
 */

/*
 * Ok, these declarations are also in <linux/kernel.h> but none of the
 * ext4 source programs needs to include it so they are duplicated here.
 */
# define NORET_TYPE 
# define ATTRIB_NORET   __attribute__((noreturn))
# define NORET_AND  noreturn,

/* bitmap.c */
extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);
void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
                struct ext4_group_desc *gdp,
                struct buffer_head *bh, int sz);
int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
                  struct ext4_group_desc *gdp,
                  struct buffer_head *bh, int sz);
void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
                struct ext4_group_desc *gdp,
                struct buffer_head *bh);
int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
                  struct ext4_group_desc *gdp,
                  struct buffer_head *bh);

/* balloc.c */
extern void ext4_validate_block_bitmap(struct super_block *sb,
                       struct ext4_group_desc *desc,
                       unsigned int block_group,
                       struct buffer_head *bh);
extern unsigned int ext4_block_group(struct super_block *sb,
            ext4_fsblk_t blocknr);
extern ext4_grpblk_t ext4_block_group_offset(struct super_block *sb,
            ext4_fsblk_t blocknr);
extern int ext4_bg_has_super(struct super_block *sb, ext4_group_t group);
extern unsigned long ext4_bg_num_gdb(struct super_block *sb,
            ext4_group_t group);
extern ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
                     ext4_fsblk_t goal,
                     unsigned int flags,
                     unsigned long *count,
                     int *errp);
extern int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
                    s64 nclusters, unsigned int flags);
extern ext4_fsblk_t ext4_count_free_clusters(struct super_block *);
extern void ext4_check_blocks_bitmap(struct super_block *);
extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
                            ext4_group_t block_group,
                            struct buffer_head ** bh);
extern int ext4_should_retry_alloc(struct super_block *sb, int *retries);

extern struct buffer_head *ext4_read_block_bitmap_nowait(struct super_block *sb,
                        ext4_group_t block_group);
extern int ext4_wait_block_bitmap(struct super_block *sb,
                  ext4_group_t block_group,
                  struct buffer_head *bh);
extern struct buffer_head *ext4_read_block_bitmap(struct super_block *sb,
                          ext4_group_t block_group);
extern void ext4_init_block_bitmap(struct super_block *sb,
                   struct buffer_head *bh,
                   ext4_group_t group,
                   struct ext4_group_desc *desc);
extern unsigned ext4_free_clusters_after_init(struct super_block *sb,
                          ext4_group_t block_group,
                          struct ext4_group_desc *gdp);
extern unsigned ext4_num_overhead_clusters(struct super_block *sb,
                       ext4_group_t block_group,
                       struct ext4_group_desc *gdp);
ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);

/* dir.c */
extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
                  struct file *,
                  struct ext4_dir_entry_2 *,
                  struct buffer_head *, unsigned int);
#define ext4_check_dir_entry(dir, filp, de, bh, offset)         \
    unlikely(__ext4_check_dir_entry(__func__, __LINE__, (dir), (filp), \
                    (de), (bh), (offset)))
extern int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
                    __u32 minor_hash,
                    struct ext4_dir_entry_2 *dirent);
extern void ext4_htree_free_dir_info(struct dir_private_info *p);

/* fsync.c */
extern int ext4_sync_file(struct file *, loff_t, loff_t, int);
extern int ext4_flush_unwritten_io(struct inode *);

/* hash.c */
extern int ext4fs_dirhash(const char *name, int len, struct
              dx_hash_info *hinfo);

/* ialloc.c */
extern struct inode *ext4_new_inode(handle_t *, struct inode *, umode_t,
                    const struct qstr *qstr, __u32 goal,
                    uid_t *owner);
extern void ext4_free_inode(handle_t *, struct inode *);
extern struct inode * ext4_orphan_get(struct super_block *, unsigned long);
extern unsigned long ext4_count_free_inodes(struct super_block *);
extern unsigned long ext4_count_dirs(struct super_block *);
extern void ext4_check_inodes_bitmap(struct super_block *);
extern void ext4_mark_bitmap_end(int start_bit, int end_bit, char *bitmap);
extern int ext4_init_inode_table(struct super_block *sb,
                 ext4_group_t group, int barrier);
extern void ext4_end_bitmap_read(struct buffer_head *bh, int uptodate);

/* mballoc.c */
extern long ext4_mb_stats;
extern long ext4_mb_max_to_scan;
extern int ext4_mb_init(struct super_block *);
extern int ext4_mb_release(struct super_block *);
extern ext4_fsblk_t ext4_mb_new_blocks(handle_t *,
                struct ext4_allocation_request *, int *);
extern int ext4_mb_reserve_blocks(struct super_block *, int);
extern void ext4_discard_preallocations(struct inode *);
extern int __init ext4_init_mballoc(void);
extern void ext4_exit_mballoc(void);
extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
                 struct buffer_head *bh, ext4_fsblk_t block,
                 unsigned long count, int flags);
extern int ext4_mb_alloc_groupinfo(struct super_block *sb,
                   ext4_group_t ngroups);
extern int ext4_mb_add_groupinfo(struct super_block *sb,
        ext4_group_t i, struct ext4_group_desc *desc);
extern int ext4_group_add_blocks(handle_t *handle, struct super_block *sb,
                ext4_fsblk_t block, unsigned long count);
extern int ext4_trim_fs(struct super_block *, struct fstrim_range *);

/* inode.c */
struct buffer_head *ext4_getblk(handle_t *, struct inode *,
                        ext4_lblk_t, int, int *);
struct buffer_head *ext4_bread(handle_t *, struct inode *,
                        ext4_lblk_t, int, int *);
int ext4_get_block(struct inode *inode, sector_t iblock,
                struct buffer_head *bh_result, int create);

extern struct inode *ext4_iget(struct super_block *, unsigned long);
extern int  ext4_write_inode(struct inode *, struct writeback_control *);
extern int  ext4_setattr(struct dentry *, struct iattr *);
extern int  ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
                struct kstat *stat);
extern void ext4_evict_inode(struct inode *);
extern void ext4_clear_inode(struct inode *);
extern int  ext4_sync_inode(handle_t *, struct inode *);
extern void ext4_dirty_inode(struct inode *, int);
extern int ext4_change_inode_journal_flag(struct inode *, int);
extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *);
extern int ext4_can_truncate(struct inode *inode);
extern void ext4_truncate(struct inode *);
extern int ext4_punch_hole(struct file *file, loff_t offset, loff_t length);
extern int ext4_truncate_restart_trans(handle_t *, struct inode *, int nblocks);
extern void ext4_set_inode_flags(struct inode *);
extern void ext4_get_inode_flags(struct ext4_inode_info *);
extern int ext4_alloc_da_blocks(struct inode *inode);
extern void ext4_set_aops(struct inode *inode);
extern int ext4_writepage_trans_blocks(struct inode *);
extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
extern int ext4_discard_partial_page_buffers(handle_t *handle,
        struct address_space *mapping, loff_t from,
        loff_t length, int flags);
extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
extern qsize_t *ext4_get_reserved_space(struct inode *inode);
extern void ext4_da_update_reserve_space(struct inode *inode,
                    int used, int quota_claim);

/* indirect.c */
extern int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
                struct ext4_map_blocks *map, int flags);
extern ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
                const struct iovec *iov, loff_t offset,
                unsigned long nr_segs);
extern int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock);
extern int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk);
extern void ext4_ind_truncate(struct inode *inode);

/* ioctl.c */
extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
extern long ext4_compat_ioctl(struct file *, unsigned int, unsigned long);

/* migrate.c */
extern int ext4_ext_migrate(struct inode *);

/* namei.c */
extern int ext4_dirent_csum_verify(struct inode *inode,
                   struct ext4_dir_entry *dirent);
extern int ext4_orphan_add(handle_t *, struct inode *);
extern int ext4_orphan_del(handle_t *, struct inode *);
extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
                __u32 start_minor_hash, __u32 *next_hash);

/* resize.c */
extern int ext4_group_add(struct super_block *sb,
                struct ext4_new_group_data *input);
extern int ext4_group_extend(struct super_block *sb,
                struct ext4_super_block *es,
                ext4_fsblk_t n_blocks_count);
extern int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count);

/* super.c */
extern int ext4_calculate_overhead(struct super_block *sb);
extern int ext4_superblock_csum_verify(struct super_block *sb,
                       struct ext4_super_block *es);
extern void ext4_superblock_csum_set(struct super_block *sb);
extern void *ext4_kvmalloc(size_t size, gfp_t flags);
extern void *ext4_kvzalloc(size_t size, gfp_t flags);
extern void ext4_kvfree(void *ptr);
extern int ext4_alloc_flex_bg_array(struct super_block *sb,
                    ext4_group_t ngroup);
extern __printf(4, 5)
void __ext4_error(struct super_block *, const char *, unsigned int,
          const char *, ...);
#define ext4_error(sb, message...)  __ext4_error(sb, __func__,  \
                             __LINE__, ## message)
extern __printf(5, 6)
void ext4_error_inode(struct inode *, const char *, unsigned int, ext4_fsblk_t,
              const char *, ...);
extern __printf(5, 6)
void ext4_error_file(struct file *, const char *, unsigned int, ext4_fsblk_t,
             const char *, ...);
extern void __ext4_std_error(struct super_block *, const char *,
                 unsigned int, int);
extern __printf(4, 5)
void __ext4_abort(struct super_block *, const char *, unsigned int,
          const char *, ...);
#define ext4_abort(sb, message...)  __ext4_abort(sb, __func__, \
                               __LINE__, ## message)
extern __printf(4, 5)
void __ext4_warning(struct super_block *, const char *, unsigned int,
            const char *, ...);
#define ext4_warning(sb, message...)    __ext4_warning(sb, __func__, \
                               __LINE__, ## message)
extern __printf(3, 4)
void ext4_msg(struct super_block *, const char *, const char *, ...);
extern void __dump_mmp_msg(struct super_block *, struct mmp_struct *mmp,
               const char *, unsigned int, const char *);
#define dump_mmp_msg(sb, mmp, msg)  __dump_mmp_msg(sb, mmp, __func__, \
                               __LINE__, msg)
extern __printf(7, 8)
void __ext4_grp_locked_error(const char *, unsigned int,
                 struct super_block *, ext4_group_t,
                 unsigned long, ext4_fsblk_t,
                 const char *, ...);
#define ext4_grp_locked_error(sb, grp, message...) \
    __ext4_grp_locked_error(__func__, __LINE__, (sb), (grp), ## message)
extern void ext4_update_dynamic_rev(struct super_block *sb);
extern int ext4_update_compat_feature(handle_t *handle, struct super_block *sb,
                    __u32 compat);
extern int ext4_update_rocompat_feature(handle_t *handle,
                    struct super_block *sb, __u32 rocompat);
extern int ext4_update_incompat_feature(handle_t *handle,
                    struct super_block *sb, __u32 incompat);
extern ext4_fsblk_t ext4_block_bitmap(struct super_block *sb,
                      struct ext4_group_desc *bg);
extern ext4_fsblk_t ext4_inode_bitmap(struct super_block *sb,
                      struct ext4_group_desc *bg);
extern ext4_fsblk_t ext4_inode_table(struct super_block *sb,
                     struct ext4_group_desc *bg);
extern __u32 ext4_free_group_clusters(struct super_block *sb,
                      struct ext4_group_desc *bg);
extern __u32 ext4_free_inodes_count(struct super_block *sb,
                 struct ext4_group_desc *bg);
extern __u32 ext4_used_dirs_count(struct super_block *sb,
                struct ext4_group_desc *bg);
extern __u32 ext4_itable_unused_count(struct super_block *sb,
                   struct ext4_group_desc *bg);
extern void ext4_block_bitmap_set(struct super_block *sb,
                  struct ext4_group_desc *bg, ext4_fsblk_t blk);
extern void ext4_inode_bitmap_set(struct super_block *sb,
                  struct ext4_group_desc *bg, ext4_fsblk_t blk);
extern void ext4_inode_table_set(struct super_block *sb,
                 struct ext4_group_desc *bg, ext4_fsblk_t blk);
extern void ext4_free_group_clusters_set(struct super_block *sb,
                     struct ext4_group_desc *bg,
                     __u32 count);
extern void ext4_free_inodes_set(struct super_block *sb,
                struct ext4_group_desc *bg, __u32 count);
extern void ext4_used_dirs_set(struct super_block *sb,
                struct ext4_group_desc *bg, __u32 count);
extern void ext4_itable_unused_set(struct super_block *sb,
                   struct ext4_group_desc *bg, __u32 count);
extern int ext4_group_desc_csum_verify(struct super_block *sb, __u32 group,
                       struct ext4_group_desc *gdp);
extern void ext4_group_desc_csum_set(struct super_block *sb, __u32 group,
                     struct ext4_group_desc *gdp);

static inline int ext4_has_group_desc_csum(struct super_block *sb)
{
    return EXT4_HAS_RO_COMPAT_FEATURE(sb,
                      EXT4_FEATURE_RO_COMPAT_GDT_CSUM |
                      EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
}

static inline ext4_fsblk_t ext4_blocks_count(struct ext4_super_block *es)
{
    return ((ext4_fsblk_t)le32_to_cpu(es->s_blocks_count_hi) << 32) |
        le32_to_cpu(es->s_blocks_count_lo);
}

static inline ext4_fsblk_t ext4_r_blocks_count(struct ext4_super_block *es)
{
    return ((ext4_fsblk_t)le32_to_cpu(es->s_r_blocks_count_hi) << 32) |
        le32_to_cpu(es->s_r_blocks_count_lo);
}

static inline ext4_fsblk_t ext4_free_blocks_count(struct ext4_super_block *es)
{
    return ((ext4_fsblk_t)le32_to_cpu(es->s_free_blocks_count_hi) << 32) |
        le32_to_cpu(es->s_free_blocks_count_lo);
}

static inline void ext4_blocks_count_set(struct ext4_super_block *es,
                     ext4_fsblk_t blk)
{
    es->s_blocks_count_lo = cpu_to_le32((u32)blk);
    es->s_blocks_count_hi = cpu_to_le32(blk >> 32);
}

static inline void ext4_free_blocks_count_set(struct ext4_super_block *es,
                          ext4_fsblk_t blk)
{
    es->s_free_blocks_count_lo = cpu_to_le32((u32)blk);
    es->s_free_blocks_count_hi = cpu_to_le32(blk >> 32);
}

static inline void ext4_r_blocks_count_set(struct ext4_super_block *es,
                       ext4_fsblk_t blk)
{
    es->s_r_blocks_count_lo = cpu_to_le32((u32)blk);
    es->s_r_blocks_count_hi = cpu_to_le32(blk >> 32);
}

static inline loff_t ext4_isize(struct ext4_inode *raw_inode)
{
    if (S_ISREG(le16_to_cpu(raw_inode->i_mode)))
        return ((loff_t)le32_to_cpu(raw_inode->i_size_high) << 32) |
            le32_to_cpu(raw_inode->i_size_lo);
    else
        return (loff_t) le32_to_cpu(raw_inode->i_size_lo);
}

static inline void ext4_isize_set(struct ext4_inode *raw_inode, loff_t i_size)
{
    raw_inode->i_size_lo = cpu_to_le32(i_size);
    raw_inode->i_size_high = cpu_to_le32(i_size >> 32);
}

static inline
struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
                        ext4_group_t group)
{
     struct ext4_group_info ***grp_info;
     long indexv, indexh;
     grp_info = EXT4_SB(sb)->s_group_info;
     indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
     indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);
     return grp_info[indexv][indexh];
}

/*
 * Reading s_groups_count requires using smp_rmb() afterwards.  See
 * the locking protocol documented in the comments of ext4_group_add()
 * in resize.c
 */
static inline ext4_group_t ext4_get_groups_count(struct super_block *sb)
{
    ext4_group_t    ngroups = EXT4_SB(sb)->s_groups_count;

    smp_rmb();
    return ngroups;
}

static inline ext4_group_t ext4_flex_group(struct ext4_sb_info *sbi,
                         ext4_group_t block_group)
{
    return block_group >> sbi->s_log_groups_per_flex;
}

static inline unsigned int ext4_flex_bg_size(struct ext4_sb_info *sbi)
{
    return 1 << sbi->s_log_groups_per_flex;
}

#define ext4_std_error(sb, errno)               \
do {                                \
    if ((errno))                        \
        __ext4_std_error((sb), __func__, __LINE__, (errno));    \
} while (0)

#ifdef CONFIG_SMP
/* Each CPU can accumulate percpu_counter_batch clusters in their local
 * counters. So we need to make sure we have free clusters more
 * than percpu_counter_batch  * nr_cpu_ids. Also add a window of 4 times.
 */
#define EXT4_FREECLUSTERS_WATERMARK (4 * (percpu_counter_batch * nr_cpu_ids))
#else
#define EXT4_FREECLUSTERS_WATERMARK 0
#endif

static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
{
    /*
     * XXX: replace with spinlock if seen contended -bzzz
     */
    down_write(&EXT4_I(inode)->i_data_sem);
    if (newsize > EXT4_I(inode)->i_disksize)
        EXT4_I(inode)->i_disksize = newsize;
    up_write(&EXT4_I(inode)->i_data_sem);
    return ;
}

struct ext4_group_info {
    unsigned long   bb_state;
    struct rb_root  bb_free_root;
    ext4_grpblk_t   bb_first_free;  /* first free block */
    ext4_grpblk_t   bb_free;    /* total free blocks */
    ext4_grpblk_t   bb_fragments;   /* nr of freespace fragments */
    ext4_grpblk_t   bb_largest_free_order;/* order of largest frag in BG */
    struct          list_head bb_prealloc_list;
#ifdef DOUBLE_CHECK
    void            *bb_bitmap;
#endif
    struct rw_semaphore alloc_sem;
    ext4_grpblk_t   bb_counters[];  /* Nr of free power-of-two-block
                     * regions, index is order.
                     * bb_counters[3] = 5 means
                     * 5 free 8-block regions. */
};

#define EXT4_GROUP_INFO_NEED_INIT_BIT       0
#define EXT4_GROUP_INFO_WAS_TRIMMED_BIT     1

#define EXT4_MB_GRP_NEED_INIT(grp)  \
    (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))

#define EXT4_MB_GRP_WAS_TRIMMED(grp)    \
    (test_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
#define EXT4_MB_GRP_SET_TRIMMED(grp)    \
    (set_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
#define EXT4_MB_GRP_CLEAR_TRIMMED(grp)  \
    (clear_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))

#define EXT4_MAX_CONTENTION     8
#define EXT4_CONTENTION_THRESHOLD   2

static inline spinlock_t *ext4_group_lock_ptr(struct super_block *sb,
                          ext4_group_t group)
{
    return bgl_lock_ptr(EXT4_SB(sb)->s_blockgroup_lock, group);
}

/*
 * Returns true if the filesystem is busy enough that attempts to
 * access the block group locks has run into contention.
 */
static inline int ext4_fs_is_busy(struct ext4_sb_info *sbi)
{
    return (atomic_read(&sbi->s_lock_busy) > EXT4_CONTENTION_THRESHOLD);
}

static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
{
    spinlock_t *lock = ext4_group_lock_ptr(sb, group);
    if (spin_trylock(lock))
        /*
         * We're able to grab the lock right away, so drop the
         * lock contention counter.
         */
        atomic_add_unless(&EXT4_SB(sb)->s_lock_busy, -1, 0);
    else {
        /*
         * The lock is busy, so bump the contention counter,
         * and then wait on the spin lock.
         */
        atomic_add_unless(&EXT4_SB(sb)->s_lock_busy, 1,
                  EXT4_MAX_CONTENTION);
        spin_lock(lock);
    }
}

static inline void ext4_unlock_group(struct super_block *sb,
                    ext4_group_t group)
{
    spin_unlock(ext4_group_lock_ptr(sb, group));
}

/*
 * Block validity checking
 */
#define ext4_check_indirect_blockref(inode, bh)             \
    ext4_check_blockref(__func__, __LINE__, inode,          \
                (__le32 *)(bh)->b_data,         \
                EXT4_ADDR_PER_BLOCK((inode)->i_sb))

#define ext4_ind_check_inode(inode)                 \
    ext4_check_blockref(__func__, __LINE__, inode,          \
                EXT4_I(inode)->i_data,          \
                EXT4_NDIR_BLOCKS)

/*
 * Inodes and files operations
 */

/* dir.c */
extern const struct file_operations ext4_dir_operations;

/* file.c */
extern const struct inode_operations ext4_file_inode_operations;
extern const struct file_operations ext4_file_operations;
extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin);
extern void ext4_unwritten_wait(struct inode *inode);

/* namei.c */
extern const struct inode_operations ext4_dir_inode_operations;
extern const struct inode_operations ext4_special_inode_operations;
extern struct dentry *ext4_get_parent(struct dentry *child);

/* symlink.c */
extern const struct inode_operations ext4_symlink_inode_operations;
extern const struct inode_operations ext4_fast_symlink_inode_operations;

/* block_validity */
extern void ext4_release_system_zone(struct super_block *sb);
extern int ext4_setup_system_zone(struct super_block *sb);
extern int __init ext4_init_system_zone(void);
extern void ext4_exit_system_zone(void);
extern int ext4_data_block_valid(struct ext4_sb_info *sbi,
                 ext4_fsblk_t start_blk,
                 unsigned int count);
extern int ext4_check_blockref(const char *, unsigned int,
                   struct inode *, __le32 *, unsigned int);

/* extents.c */
extern int ext4_ext_tree_init(handle_t *handle, struct inode *);
extern int ext4_ext_writepage_trans_blocks(struct inode *, int);
extern int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks,
                       int chunk);
extern int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
                   struct ext4_map_blocks *map, int flags);
extern void ext4_ext_truncate(struct inode *);
extern int ext4_ext_punch_hole(struct file *file, loff_t offset,
                loff_t length);
extern void ext4_ext_init(struct super_block *);
extern void ext4_ext_release(struct super_block *);
extern long ext4_fallocate(struct file *file, int mode, loff_t offset,
              loff_t len);
extern int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
              ssize_t len);
extern int ext4_map_blocks(handle_t *handle, struct inode *inode,
               struct ext4_map_blocks *map, int flags);
extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
            __u64 start, __u64 len);
/* move_extent.c */
extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
                 __u64 start_orig, __u64 start_donor,
                 __u64 len, __u64 *moved_len);

/* page-io.c */
extern int __init ext4_init_pageio(void);
extern void ext4_add_complete_io(ext4_io_end_t *io_end);
extern void ext4_exit_pageio(void);
extern void ext4_ioend_wait(struct inode *);
extern void ext4_free_io_end(ext4_io_end_t *io);
extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
extern void ext4_io_submit(struct ext4_io_submit *io);
extern int ext4_bio_write_page(struct ext4_io_submit *io,
                   struct page *page,
                   int len,
                   struct writeback_control *wbc);

/* mmp.c */
extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t);
extern void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp);
extern int ext4_mmp_csum_verify(struct super_block *sb,
                struct mmp_struct *mmp);

/* BH_Uninit flag: blocks are allocated but uninitialized on disk */
enum ext4_state_bits {
    BH_Uninit   /* blocks are allocated but uninitialized on disk */
      = BH_JBDPrivateStart,
    BH_AllocFromCluster,    /* allocated blocks were part of already
                 * allocated cluster. Note that this flag will
                 * never, ever appear in a buffer_head's state
                 * flag. See EXT4_MAP_FROM_CLUSTER to see where
                 * this is used. */
    BH_Da_Mapped,   /* Delayed allocated block that now has a mapping. This
             * flag is set when ext4_map_blocks is called on a
             * delayed allocated block to get its real mapping. */
};

BUFFER_FNS(Uninit, uninit)
TAS_BUFFER_FNS(Uninit, uninit)
BUFFER_FNS(Da_Mapped, da_mapped)

/*
 * Add new method to test wether block and inode bitmaps are properly
 * initialized. With uninit_bg reading the block from disk is not enough
 * to mark the bitmap uptodate. We need to also zero-out the bitmap
 */
#define BH_BITMAP_UPTODATE BH_JBDPrivateStart

static inline int bitmap_uptodate(struct buffer_head *bh)
{
    return (buffer_uptodate(bh) &&
            test_bit(BH_BITMAP_UPTODATE, &(bh)->b_state));
}
static inline void set_bitmap_uptodate(struct buffer_head *bh)
{
    set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);
}

/*
 * Disable DIO read nolock optimization, so new dioreaders will be forced
 * to grab i_mutex
 */
static inline void ext4_inode_block_unlocked_dio(struct inode *inode)
{
    ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
    smp_mb();
}
static inline void ext4_inode_resume_unlocked_dio(struct inode *inode)
{
    smp_mb();
    ext4_clear_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
}

#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)

/* For ioend & aio unwritten conversion wait queues */
#define EXT4_WQ_HASH_SZ     37
#define ext4_ioend_wq(v)   (&ext4__ioend_wq[((unsigned long)(v)) %\
                        EXT4_WQ_HASH_SZ])
#define ext4_aio_mutex(v)  (&ext4__aio_mutex[((unsigned long)(v)) %\
                         EXT4_WQ_HASH_SZ])
extern wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
extern struct mutex ext4__aio_mutex[EXT4_WQ_HASH_SZ];

#define EXT4_RESIZING   0
extern int ext4_resize_begin(struct super_block *sb);
extern void ext4_resize_end(struct super_block *sb);

#endif  /* __KERNEL__ */

#include "ext4_extents.h"

#endif  /* _EXT4_H */