ext2.h

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/*
 * 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
 */
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/blockgroup_lock.h>
#include <linux/percpu_counter.h>
#include <linux/rbtree.h>

/* XXX Here for now... not interested in restructing headers JUST now */

/* data type for block offset of block group */
typedef int ext2_grpblk_t;

/* data type for filesystem-wide blocks number */
typedef unsigned long ext2_fsblk_t;

#define E2FSBLK "%lu"

struct ext2_reserve_window {
    ext2_fsblk_t        _rsv_start; /* First byte reserved */
    ext2_fsblk_t        _rsv_end;   /* Last byte reserved or 0 */
};

struct ext2_reserve_window_node {
    struct rb_node      rsv_node;
    __u32           rsv_goal_size;
    __u32           rsv_alloc_hit;
    struct ext2_reserve_window  rsv_window;
};

struct ext2_block_alloc_info {
    /* information about reservation window */
    struct ext2_reserve_window_node rsv_window_node;
    /*
     * was i_next_alloc_block in ext2_inode_info
     * is the logical (file-relative) number of the
     * most-recently-allocated block in this file.
     * We use this for detecting linearly ascending allocation requests.
     */
    __u32           last_alloc_logical_block;
    /*
     * Was i_next_alloc_goal in ext2_inode_info
     * is the *physical* companion to i_next_alloc_block.
     * it the the physical block number of the block which was most-recentl
     * allocated to this file.  This give us the goal (target) for the next
     * allocation when we detect linearly ascending requests.
     */
    ext2_fsblk_t        last_alloc_physical_block;
};

#define rsv_start rsv_window._rsv_start
#define rsv_end rsv_window._rsv_end

/*
 * second extended-fs super-block data in memory
 */
struct ext2_sb_info {
    unsigned long s_frag_size;  /* Size of a fragment in bytes */
    unsigned long s_frags_per_block;/* Number of fragments per block */
    unsigned long s_inodes_per_block;/* Number of inodes per block */
    unsigned long s_frags_per_group;/* Number of fragments in a group */
    unsigned long s_blocks_per_group;/* Number of blocks 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 */
    unsigned long s_groups_count;   /* Number of groups in the fs */
    unsigned long s_overhead_last;  /* Last calculated overhead */
    unsigned long s_blocks_last;    /* Last seen block count */
    struct buffer_head * s_sbh; /* Buffer containing the super block */
    struct ext2_super_block * s_es; /* Pointer to the super block in the buffer */
    struct buffer_head ** s_group_desc;
    unsigned long  s_mount_opt;
    unsigned long 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;
    spinlock_t s_next_gen_lock;
    u32 s_next_generation;
    unsigned long s_dir_count;
    u8 *s_debts;
    struct percpu_counter s_freeblocks_counter;
    struct percpu_counter s_freeinodes_counter;
    struct percpu_counter s_dirs_counter;
    struct blockgroup_lock *s_blockgroup_lock;
    /* root of the per fs reservation window tree */
    spinlock_t s_rsv_window_lock;
    struct rb_root s_rsv_window_root;
    struct ext2_reserve_window_node s_rsv_window_head;
    /*
     * s_lock protects against concurrent modifications of s_mount_state,
     * s_blocks_last, s_overhead_last and the content of superblock's
     * buffer pointed to by sbi->s_es.
     *
     * Note: It is used in ext2_show_options() to provide a consistent view
     * of the mount options.
     */
    spinlock_t s_lock;
};

static inline spinlock_t *
sb_bgl_lock(struct ext2_sb_info *sbi, unsigned int block_group)
{
    return bgl_lock_ptr(sbi->s_blockgroup_lock, block_group);
}

/*
 * Define EXT2FS_DEBUG to produce debug messages
 */
#undef EXT2FS_DEBUG

/*
 * Define EXT2_RESERVATION to reserve data blocks for expanding files
 */
#define EXT2_DEFAULT_RESERVE_BLOCKS     8
/*max window size: 1024(direct blocks) + 3([t,d]indirect blocks) */
#define EXT2_MAX_RESERVE_BLOCKS         1027
#define EXT2_RESERVE_WINDOW_NOT_ALLOCATED 0
/*
 * The second extended file system version
 */
#define EXT2FS_DATE     "95/08/09"
#define EXT2FS_VERSION      "0.5b"

/*
 * Debug code
 */
#ifdef EXT2FS_DEBUG
#   define ext2_debug(f, a...)  { \
                    printk ("EXT2-fs DEBUG (%s, %d): %s:", \
                        __FILE__, __LINE__, __func__); \
                    printk (f, ## a); \
                    }
#else
#   define ext2_debug(f, a...)  
#endif

/*
 * Special inode numbers
 */
#define EXT2_BAD_INO         1  /* Bad blocks inode */
#define EXT2_ROOT_INO        2  /* Root inode */
#define EXT2_BOOT_LOADER_INO     5  /* Boot loader inode */
#define EXT2_UNDEL_DIR_INO   6  /* Undelete directory inode */

/* First non-reserved inode for old ext2 filesystems */
#define EXT2_GOOD_OLD_FIRST_INO 11

static inline struct ext2_sb_info *EXT2_SB(struct super_block *sb)
{
    return sb->s_fs_info;
}

/*
 * Macro-instructions used to manage several block sizes
 */
#define EXT2_MIN_BLOCK_SIZE     1024
#define EXT2_MAX_BLOCK_SIZE     4096
#define EXT2_MIN_BLOCK_LOG_SIZE       10
#define EXT2_BLOCK_SIZE(s)      ((s)->s_blocksize)
#define EXT2_ADDR_PER_BLOCK(s)      (EXT2_BLOCK_SIZE(s) / sizeof (__u32))
#define EXT2_BLOCK_SIZE_BITS(s)     ((s)->s_blocksize_bits)
#define EXT2_ADDR_PER_BLOCK_BITS(s) (EXT2_SB(s)->s_addr_per_block_bits)
#define EXT2_INODE_SIZE(s)      (EXT2_SB(s)->s_inode_size)
#define EXT2_FIRST_INO(s)       (EXT2_SB(s)->s_first_ino)

/*
 * Macro-instructions used to manage fragments
 */
#define EXT2_MIN_FRAG_SIZE      1024
#define EXT2_MAX_FRAG_SIZE      4096
#define EXT2_MIN_FRAG_LOG_SIZE        10
#define EXT2_FRAG_SIZE(s)       (EXT2_SB(s)->s_frag_size)
#define EXT2_FRAGS_PER_BLOCK(s)     (EXT2_SB(s)->s_frags_per_block)

/*
 * Structure of a blocks group descriptor
 */
struct ext2_group_desc
{
    __le32  bg_block_bitmap;        /* Blocks bitmap block */
    __le32  bg_inode_bitmap;        /* Inodes bitmap block */
    __le32  bg_inode_table;     /* Inodes table block */
    __le16  bg_free_blocks_count;   /* Free blocks count */
    __le16  bg_free_inodes_count;   /* Free inodes count */
    __le16  bg_used_dirs_count; /* Directories count */
    __le16  bg_pad;
    __le32  bg_reserved[3];
};

/*
 * Macro-instructions used to manage group descriptors
 */
#define EXT2_BLOCKS_PER_GROUP(s)    (EXT2_SB(s)->s_blocks_per_group)
#define EXT2_DESC_PER_BLOCK(s)      (EXT2_SB(s)->s_desc_per_block)
#define EXT2_INODES_PER_GROUP(s)    (EXT2_SB(s)->s_inodes_per_group)
#define EXT2_DESC_PER_BLOCK_BITS(s) (EXT2_SB(s)->s_desc_per_block_bits)

/*
 * Constants relative to the data blocks
 */
#define EXT2_NDIR_BLOCKS        12
#define EXT2_IND_BLOCK          EXT2_NDIR_BLOCKS
#define EXT2_DIND_BLOCK         (EXT2_IND_BLOCK + 1)
#define EXT2_TIND_BLOCK         (EXT2_DIND_BLOCK + 1)
#define EXT2_N_BLOCKS           (EXT2_TIND_BLOCK + 1)

/*
 * Inode flags (GETFLAGS/SETFLAGS)
 */
#define EXT2_SECRM_FL           FS_SECRM_FL /* Secure deletion */
#define EXT2_UNRM_FL            FS_UNRM_FL  /* Undelete */
#define EXT2_COMPR_FL           FS_COMPR_FL /* Compress file */
#define EXT2_SYNC_FL            FS_SYNC_FL  /* Synchronous updates */
#define EXT2_IMMUTABLE_FL       FS_IMMUTABLE_FL /* Immutable file */
#define EXT2_APPEND_FL          FS_APPEND_FL    /* writes to file may only append */
#define EXT2_NODUMP_FL          FS_NODUMP_FL    /* do not dump file */
#define EXT2_NOATIME_FL         FS_NOATIME_FL   /* do not update atime */
/* Reserved for compression usage... */
#define EXT2_DIRTY_FL           FS_DIRTY_FL
#define EXT2_COMPRBLK_FL        FS_COMPRBLK_FL  /* One or more compressed clusters */
#define EXT2_NOCOMP_FL          FS_NOCOMP_FL    /* Don't compress */
#define EXT2_ECOMPR_FL          FS_ECOMPR_FL    /* Compression error */
/* End compression flags --- maybe not all used */  
#define EXT2_BTREE_FL           FS_BTREE_FL /* btree format dir */
#define EXT2_INDEX_FL           FS_INDEX_FL /* hash-indexed directory */
#define EXT2_IMAGIC_FL          FS_IMAGIC_FL    /* AFS directory */
#define EXT2_JOURNAL_DATA_FL        FS_JOURNAL_DATA_FL /* Reserved for ext3 */
#define EXT2_NOTAIL_FL          FS_NOTAIL_FL    /* file tail should not be merged */
#define EXT2_DIRSYNC_FL         FS_DIRSYNC_FL   /* dirsync behaviour (directories only) */
#define EXT2_TOPDIR_FL          FS_TOPDIR_FL    /* Top of directory hierarchies*/
#define EXT2_RESERVED_FL        FS_RESERVED_FL  /* reserved for ext2 lib */

#define EXT2_FL_USER_VISIBLE        FS_FL_USER_VISIBLE  /* User visible flags */
#define EXT2_FL_USER_MODIFIABLE     FS_FL_USER_MODIFIABLE   /* User modifiable flags */

/* Flags that should be inherited by new inodes from their parent. */
#define EXT2_FL_INHERITED (EXT2_SECRM_FL | EXT2_UNRM_FL | EXT2_COMPR_FL |\
               EXT2_SYNC_FL | EXT2_NODUMP_FL |\
               EXT2_NOATIME_FL | EXT2_COMPRBLK_FL |\
               EXT2_NOCOMP_FL | EXT2_JOURNAL_DATA_FL |\
               EXT2_NOTAIL_FL | EXT2_DIRSYNC_FL)

/* Flags that are appropriate for regular files (all but dir-specific ones). */
#define EXT2_REG_FLMASK (~(EXT2_DIRSYNC_FL | EXT2_TOPDIR_FL))

/* Flags that are appropriate for non-directories/regular files. */
#define EXT2_OTHER_FLMASK (EXT2_NODUMP_FL | EXT2_NOATIME_FL)

/* Mask out flags that are inappropriate for the given type of inode. */
static inline __u32 ext2_mask_flags(umode_t mode, __u32 flags)
{
    if (S_ISDIR(mode))
        return flags;
    else if (S_ISREG(mode))
        return flags & EXT2_REG_FLMASK;
    else
        return flags & EXT2_OTHER_FLMASK;
}

/*
 * ioctl commands
 */
#define EXT2_IOC_GETFLAGS       FS_IOC_GETFLAGS
#define EXT2_IOC_SETFLAGS       FS_IOC_SETFLAGS
#define EXT2_IOC_GETVERSION     FS_IOC_GETVERSION
#define EXT2_IOC_SETVERSION     FS_IOC_SETVERSION
#define EXT2_IOC_GETRSVSZ       _IOR('f', 5, long)
#define EXT2_IOC_SETRSVSZ       _IOW('f', 6, long)

/*
 * ioctl commands in 32 bit emulation
 */
#define EXT2_IOC32_GETFLAGS     FS_IOC32_GETFLAGS
#define EXT2_IOC32_SETFLAGS     FS_IOC32_SETFLAGS
#define EXT2_IOC32_GETVERSION       FS_IOC32_GETVERSION
#define EXT2_IOC32_SETVERSION       FS_IOC32_SETVERSION

/*
 * Structure of an inode on the disk
 */
struct ext2_inode {
    __le16  i_mode;     /* File mode */
    __le16  i_uid;      /* Low 16 bits of Owner Uid */
    __le32  i_size;     /* Size in bytes */
    __le32  i_atime;    /* Access time */
    __le32  i_ctime;    /* Creation 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;   /* Blocks count */
    __le32  i_flags;    /* File flags */
    union {
        struct {
            __le32  l_i_reserved1;
        } linux1;
        struct {
            __le32  h_i_translator;
        } hurd1;
        struct {
            __le32  m_i_reserved1;
        } masix1;
    } osd1;             /* OS dependent 1 */
    __le32  i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
    __le32  i_generation;   /* File version (for NFS) */
    __le32  i_file_acl; /* File ACL */
    __le32  i_dir_acl;  /* Directory ACL */
    __le32  i_faddr;    /* Fragment address */
    union {
        struct {
            __u8    l_i_frag;   /* Fragment number */
            __u8    l_i_fsize;  /* Fragment size */
            __u16   i_pad1;
            __le16  l_i_uid_high;   /* these 2 fields    */
            __le16  l_i_gid_high;   /* were reserved2[0] */
            __u32   l_i_reserved2;
        } linux2;
        struct {
            __u8    h_i_frag;   /* Fragment number */
            __u8    h_i_fsize;  /* Fragment size */
            __le16  h_i_mode_high;
            __le16  h_i_uid_high;
            __le16  h_i_gid_high;
            __le32  h_i_author;
        } hurd2;
        struct {
            __u8    m_i_frag;   /* Fragment number */
            __u8    m_i_fsize;  /* Fragment size */
            __u16   m_pad1;
            __u32   m_i_reserved2[2];
        } masix2;
    } osd2;             /* OS dependent 2 */
};

#define i_size_high i_dir_acl

#define i_reserved1 osd1.linux1.l_i_reserved1
#define i_frag      osd2.linux2.l_i_frag
#define i_fsize     osd2.linux2.l_i_fsize
#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_reserved2 osd2.linux2.l_i_reserved2

/*
 * File system states
 */
#define EXT2_VALID_FS           0x0001  /* Unmounted cleanly */
#define EXT2_ERROR_FS           0x0002  /* Errors detected */

/*
 * Mount flags
 */
#define EXT2_MOUNT_CHECK        0x000001  /* Do mount-time checks */
#define EXT2_MOUNT_OLDALLOC     0x000002  /* Don't use the new Orlov allocator */
#define EXT2_MOUNT_GRPID        0x000004  /* Create files with directory's group */
#define EXT2_MOUNT_DEBUG        0x000008  /* Some debugging messages */
#define EXT2_MOUNT_ERRORS_CONT      0x000010  /* Continue on errors */
#define EXT2_MOUNT_ERRORS_RO        0x000020  /* Remount fs ro on errors */
#define EXT2_MOUNT_ERRORS_PANIC     0x000040  /* Panic on errors */
#define EXT2_MOUNT_MINIX_DF     0x000080  /* Mimics the Minix statfs */
#define EXT2_MOUNT_NOBH         0x000100  /* No buffer_heads */
#define EXT2_MOUNT_NO_UID32     0x000200  /* Disable 32-bit UIDs */
#define EXT2_MOUNT_XATTR_USER       0x004000  /* Extended user attributes */
#define EXT2_MOUNT_POSIX_ACL        0x008000  /* POSIX Access Control Lists */
#define EXT2_MOUNT_XIP          0x010000  /* Execute in place */
#define EXT2_MOUNT_USRQUOTA     0x020000  /* user quota */
#define EXT2_MOUNT_GRPQUOTA     0x040000  /* group quota */
#define EXT2_MOUNT_RESERVATION      0x080000  /* Preallocation */


#define clear_opt(o, opt)       o &= ~EXT2_MOUNT_##opt
#define set_opt(o, opt)         o |= EXT2_MOUNT_##opt
#define test_opt(sb, opt)       (EXT2_SB(sb)->s_mount_opt & \
                     EXT2_MOUNT_##opt)
/*
 * Maximal mount counts between two filesystem checks
 */
#define EXT2_DFL_MAX_MNT_COUNT      20  /* Allow 20 mounts */
#define EXT2_DFL_CHECKINTERVAL      0   /* Don't use interval check */

/*
 * Behaviour when detecting errors
 */
#define EXT2_ERRORS_CONTINUE        1   /* Continue execution */
#define EXT2_ERRORS_RO          2   /* Remount fs read-only */
#define EXT2_ERRORS_PANIC       3   /* Panic */
#define EXT2_ERRORS_DEFAULT     EXT2_ERRORS_CONTINUE

/*
 * Structure of the super block
 */
struct ext2_super_block {
    __le32  s_inodes_count;     /* Inodes count */
    __le32  s_blocks_count;     /* Blocks count */
    __le32  s_r_blocks_count;   /* Reserved blocks count */
    __le32  s_free_blocks_count;    /* Free blocks count */
    __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_frag_size;    /* Fragment size */
    __le32  s_blocks_per_group; /* # Blocks per group */
    __le32  s_frags_per_group;  /* # Fragments per group */
    __le32  s_inodes_per_group; /* # Inodes per group */
    __le32  s_mtime;        /* Mount time */
    __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 */
    __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 */
    __le16  s_def_resuid;       /* Default uid for reserved blocks */
    __le16  s_def_resgid;       /* Default gid for reserved blocks */
    /*
     * These fields are for EXT2_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 */
    __le32  s_feature_incompat;     /* incompatible feature set */
    __le32  s_feature_ro_compat;    /* readonly-compatible feature set */
    __u8    s_uuid[16];     /* 128-bit uuid for volume */
    char    s_volume_name[16];  /* volume name */
    char    s_last_mounted[64];     /* directory where last mounted */
    __le32  s_algorithm_usage_bitmap; /* For compression */
    /*
     * Performance hints.  Directory preallocation should only
     * happen if the EXT2_COMPAT_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 */
    __u16   s_padding1;
    /*
     * Journaling support valid if EXT3_FEATURE_COMPAT_HAS_JOURNAL set.
     */
    __u8    s_journal_uuid[16]; /* uuid of journal superblock */
    __u32   s_journal_inum;     /* inode number of journal file */
    __u32   s_journal_dev;      /* device number of journal file */
    __u32   s_last_orphan;      /* start of list of inodes to delete */
    __u32   s_hash_seed[4];     /* HTREE hash seed */
    __u8    s_def_hash_version; /* Default hash version to use */
    __u8    s_reserved_char_pad;
    __u16   s_reserved_word_pad;
    __le32  s_default_mount_opts;
    __le32  s_first_meta_bg;    /* First metablock block group */
    __u32   s_reserved[190];    /* Padding to the end of the block */
};

/*
 * Codes for operating systems
 */
#define EXT2_OS_LINUX       0
#define EXT2_OS_HURD        1
#define EXT2_OS_MASIX       2
#define EXT2_OS_FREEBSD     3
#define EXT2_OS_LITES       4

/*
 * Revision levels
 */
#define EXT2_GOOD_OLD_REV   0   /* The good old (original) format */
#define EXT2_DYNAMIC_REV    1   /* V2 format w/ dynamic inode sizes */

#define EXT2_CURRENT_REV    EXT2_GOOD_OLD_REV
#define EXT2_MAX_SUPP_REV   EXT2_DYNAMIC_REV

#define EXT2_GOOD_OLD_INODE_SIZE 128

/*
 * Feature set definitions
 */

#define EXT2_HAS_COMPAT_FEATURE(sb,mask)            \
    ( EXT2_SB(sb)->s_es->s_feature_compat & cpu_to_le32(mask) )
#define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)         \
    ( EXT2_SB(sb)->s_es->s_feature_ro_compat & cpu_to_le32(mask) )
#define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)          \
    ( EXT2_SB(sb)->s_es->s_feature_incompat & cpu_to_le32(mask) )
#define EXT2_SET_COMPAT_FEATURE(sb,mask)            \
    EXT2_SB(sb)->s_es->s_feature_compat |= cpu_to_le32(mask)
#define EXT2_SET_RO_COMPAT_FEATURE(sb,mask)         \
    EXT2_SB(sb)->s_es->s_feature_ro_compat |= cpu_to_le32(mask)
#define EXT2_SET_INCOMPAT_FEATURE(sb,mask)          \
    EXT2_SB(sb)->s_es->s_feature_incompat |= cpu_to_le32(mask)
#define EXT2_CLEAR_COMPAT_FEATURE(sb,mask)          \
    EXT2_SB(sb)->s_es->s_feature_compat &= ~cpu_to_le32(mask)
#define EXT2_CLEAR_RO_COMPAT_FEATURE(sb,mask)           \
    EXT2_SB(sb)->s_es->s_feature_ro_compat &= ~cpu_to_le32(mask)
#define EXT2_CLEAR_INCOMPAT_FEATURE(sb,mask)            \
    EXT2_SB(sb)->s_es->s_feature_incompat &= ~cpu_to_le32(mask)

#define EXT2_FEATURE_COMPAT_DIR_PREALLOC    0x0001
#define EXT2_FEATURE_COMPAT_IMAGIC_INODES   0x0002
#define EXT3_FEATURE_COMPAT_HAS_JOURNAL     0x0004
#define EXT2_FEATURE_COMPAT_EXT_ATTR        0x0008
#define EXT2_FEATURE_COMPAT_RESIZE_INO      0x0010
#define EXT2_FEATURE_COMPAT_DIR_INDEX       0x0020
#define EXT2_FEATURE_COMPAT_ANY         0xffffffff

#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE   0x0002
#define EXT2_FEATURE_RO_COMPAT_BTREE_DIR    0x0004
#define EXT2_FEATURE_RO_COMPAT_ANY      0xffffffff

#define EXT2_FEATURE_INCOMPAT_COMPRESSION   0x0001
#define EXT2_FEATURE_INCOMPAT_FILETYPE      0x0002
#define EXT3_FEATURE_INCOMPAT_RECOVER       0x0004
#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV   0x0008
#define EXT2_FEATURE_INCOMPAT_META_BG       0x0010
#define EXT2_FEATURE_INCOMPAT_ANY       0xffffffff

#define EXT2_FEATURE_COMPAT_SUPP    EXT2_FEATURE_COMPAT_EXT_ATTR
#define EXT2_FEATURE_INCOMPAT_SUPP  (EXT2_FEATURE_INCOMPAT_FILETYPE| \
                     EXT2_FEATURE_INCOMPAT_META_BG)
#define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                     EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
                     EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
#define EXT2_FEATURE_RO_COMPAT_UNSUPPORTED  ~EXT2_FEATURE_RO_COMPAT_SUPP
#define EXT2_FEATURE_INCOMPAT_UNSUPPORTED   ~EXT2_FEATURE_INCOMPAT_SUPP

/*
 * Default values for user and/or group using reserved blocks
 */
#define EXT2_DEF_RESUID     0
#define EXT2_DEF_RESGID     0

/*
 * Default mount options
 */
#define EXT2_DEFM_DEBUG     0x0001
#define EXT2_DEFM_BSDGROUPS 0x0002
#define EXT2_DEFM_XATTR_USER    0x0004
#define EXT2_DEFM_ACL       0x0008
#define EXT2_DEFM_UID16     0x0010
    /* Not used by ext2, but reserved for use by ext3 */
#define EXT3_DEFM_JMODE     0x0060 
#define EXT3_DEFM_JMODE_DATA    0x0020
#define EXT3_DEFM_JMODE_ORDERED 0x0040
#define EXT3_DEFM_JMODE_WBACK   0x0060

/*
 * Structure of a directory entry
 */

struct ext2_dir_entry {
    __le32  inode;          /* Inode number */
    __le16  rec_len;        /* Directory entry length */
    __le16  name_len;       /* Name length */
    char    name[];         /* File name, up to EXT2_NAME_LEN */
};

/*
 * The new version of the directory entry.  Since EXT2 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 ext2_dir_entry_2 {
    __le32  inode;          /* Inode number */
    __le16  rec_len;        /* Directory entry length */
    __u8    name_len;       /* Name length */
    __u8    file_type;
    char    name[];         /* File name, up to EXT2_NAME_LEN */
};

/*
 * Ext2 directory file types.  Only the low 3 bits are used.  The
 * other bits are reserved for now.
 */
enum {
    EXT2_FT_UNKNOWN     = 0,
    EXT2_FT_REG_FILE    = 1,
    EXT2_FT_DIR     = 2,
    EXT2_FT_CHRDEV      = 3,
    EXT2_FT_BLKDEV      = 4,
    EXT2_FT_FIFO        = 5,
    EXT2_FT_SOCK        = 6,
    EXT2_FT_SYMLINK     = 7,
    EXT2_FT_MAX
};

/*
 * EXT2_DIR_PAD defines the directory entries boundaries
 *
 * NOTE: It must be a multiple of 4
 */
#define EXT2_DIR_PAD            4
#define EXT2_DIR_ROUND          (EXT2_DIR_PAD - 1)
#define EXT2_DIR_REC_LEN(name_len)  (((name_len) + 8 + EXT2_DIR_ROUND) & \
                     ~EXT2_DIR_ROUND)
#define EXT2_MAX_REC_LEN        ((1<<16)-1)

static inline void verify_offsets(void)
{
#define A(x,y) BUILD_BUG_ON(x != offsetof(struct ext2_super_block, y));
    A(EXT2_SB_MAGIC_OFFSET, s_magic);
    A(EXT2_SB_BLOCKS_OFFSET, s_blocks_count);
    A(EXT2_SB_BSIZE_OFFSET, s_log_block_size);
#undef A
}

/*
 * ext2 mount options
 */
struct ext2_mount_options {
    unsigned long s_mount_opt;
    kuid_t s_resuid;
    kgid_t s_resgid;
};

/*
 * second extended file system inode data in memory
 */
struct ext2_inode_info {
    __le32  i_data[15];
    __u32   i_flags;
    __u32   i_faddr;
    __u8    i_frag_no;
    __u8    i_frag_size;
    __u16   i_state;
    __u32   i_file_acl;
    __u32   i_dir_acl;
    __u32   i_dtime;

    /*
     * 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 used 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.
     */
    __u32   i_block_group;

    /* block reservation info */
    struct ext2_block_alloc_info *i_block_alloc_info;

    __u32   i_dir_start_lookup;
#ifdef CONFIG_EXT2_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
    rwlock_t i_meta_lock;

    /*
     * truncate_mutex is for serialising ext2_truncate() against
     * ext2_getblock().  It also protects the internals of the inode's
     * reservation data structures: ext2_reserve_window and
     * ext2_reserve_window_node.
     */
    struct mutex truncate_mutex;
    struct inode    vfs_inode;
    struct list_head i_orphan;  /* unlinked but open inodes */
};

/*
 * Inode dynamic state flags
 */
#define EXT2_STATE_NEW          0x00000001 /* inode is newly created */


/*
 * Function prototypes
 */

/*
 * Ok, these declarations are also in <linux/kernel.h> but none of the
 * ext2 source programs needs to include it so they are duplicated here.
 */

static inline struct ext2_inode_info *EXT2_I(struct inode *inode)
{
    return container_of(inode, struct ext2_inode_info, vfs_inode);
}

/* balloc.c */
extern int ext2_bg_has_super(struct super_block *sb, int group);
extern unsigned long ext2_bg_num_gdb(struct super_block *sb, int group);
extern ext2_fsblk_t ext2_new_block(struct inode *, unsigned long, int *);
extern ext2_fsblk_t ext2_new_blocks(struct inode *, unsigned long,
                unsigned long *, int *);
extern void ext2_free_blocks (struct inode *, unsigned long,
                  unsigned long);
extern unsigned long ext2_count_free_blocks (struct super_block *);
extern unsigned long ext2_count_dirs (struct super_block *);
extern void ext2_check_blocks_bitmap (struct super_block *);
extern struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
                            unsigned int block_group,
                            struct buffer_head ** bh);
extern void ext2_discard_reservation (struct inode *);
extern int ext2_should_retry_alloc(struct super_block *sb, int *retries);
extern void ext2_init_block_alloc_info(struct inode *);
extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_window_node *rsv);

/* dir.c */
extern int ext2_add_link (struct dentry *, struct inode *);
extern ino_t ext2_inode_by_name(struct inode *, struct qstr *);
extern int ext2_make_empty(struct inode *, struct inode *);
extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,struct qstr *, struct page **);
extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
extern int ext2_empty_dir (struct inode *);
extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);
extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, struct inode *, int);

/* ialloc.c */
extern struct inode * ext2_new_inode (struct inode *, umode_t, const struct qstr *);
extern void ext2_free_inode (struct inode *);
extern unsigned long ext2_count_free_inodes (struct super_block *);
extern void ext2_check_inodes_bitmap (struct super_block *);
extern unsigned long ext2_count_free (struct buffer_head *, unsigned);

/* inode.c */
extern struct inode *ext2_iget (struct super_block *, unsigned long);
extern int ext2_write_inode (struct inode *, struct writeback_control *);
extern void ext2_evict_inode(struct inode *);
extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
extern int ext2_setattr (struct dentry *, struct iattr *);
extern void ext2_set_inode_flags(struct inode *inode);
extern void ext2_get_inode_flags(struct ext2_inode_info *);
extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
               u64 start, u64 len);

/* ioctl.c */
extern long ext2_ioctl(struct file *, unsigned int, unsigned long);
extern long ext2_compat_ioctl(struct file *, unsigned int, unsigned long);

/* namei.c */
struct dentry *ext2_get_parent(struct dentry *child);

/* super.c */
extern __printf(3, 4)
void ext2_error(struct super_block *, const char *, const char *, ...);
extern __printf(3, 4)
void ext2_msg(struct super_block *, const char *, const char *, ...);
extern void ext2_update_dynamic_rev (struct super_block *sb);
extern void ext2_write_super (struct super_block *);

/*
 * Inodes and files operations
 */

/* dir.c */
extern const struct file_operations ext2_dir_operations;

/* file.c */
extern int ext2_fsync(struct file *file, loff_t start, loff_t end,
              int datasync);
extern const struct inode_operations ext2_file_inode_operations;
extern const struct file_operations ext2_file_operations;
extern const struct file_operations ext2_xip_file_operations;

/* inode.c */
extern const struct address_space_operations ext2_aops;
extern const struct address_space_operations ext2_aops_xip;
extern const struct address_space_operations ext2_nobh_aops;

/* namei.c */
extern const struct inode_operations ext2_dir_inode_operations;
extern const struct inode_operations ext2_special_inode_operations;

/* symlink.c */
extern const struct inode_operations ext2_fast_symlink_inode_operations;
extern const struct inode_operations ext2_symlink_inode_operations;

static inline ext2_fsblk_t
ext2_group_first_block_no(struct super_block *sb, unsigned long group_no)
{
    return group_no * (ext2_fsblk_t)EXT2_BLOCKS_PER_GROUP(sb) +
        le32_to_cpu(EXT2_SB(sb)->s_es->s_first_data_block);
}

#define ext2_set_bit    __test_and_set_bit_le
#define ext2_clear_bit  __test_and_clear_bit_le
#define ext2_test_bit   test_bit_le
#define ext2_find_first_zero_bit    find_first_zero_bit_le
#define ext2_find_next_zero_bit     find_next_zero_bit_le