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ext2_fs.h

/*
 *  linux/include/linux/ext2_fs.h
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * 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 _LINUX_EXT2_FS_H
#define _LINUX_EXT2_FS_H

#include <ext2fs/ext2_types.h>            /* Changed from linux/types.h */

/*
 * The second extended filesystem constants/structures
 */

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

/*
 * Define EXT2_PREALLOCATE to preallocate data blocks for expanding files
 */
#define EXT2_PREALLOCATE
#define EXT2_DEFAULT_PREALLOC_BLOCKS      8

/*
 * The second extended file system version
 */
#define EXT2FS_DATE           "95/08/09"
#define EXT2FS_VERSION        "0.5b"

/*
 * Special inode numbers
 */
#define EXT2_BAD_INO           1    /* Bad blocks inode */
#define EXT2_ROOT_INO          2    /* Root inode */
#define EXT2_ACL_IDX_INO       3    /* ACL inode */
#define EXT2_ACL_DATA_INO      4    /* ACL inode */
#define EXT2_BOOT_LOADER_INO   5    /* Boot loader inode */
#define EXT2_UNDEL_DIR_INO     6    /* Undelete directory inode */
#define EXT2_RESIZE_INO        7    /* Reserved group descriptors inode */
#define EXT2_JOURNAL_INO       8    /* Journal inode */

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

/*
 * The second extended file system magic number
 */
#define EXT2_SUPER_MAGIC      0xEF53

#ifdef __KERNEL__
#define EXT2_SB(sb)     (&((sb)->u.ext2_sb))
#else
/* Assume that user mode programs are passing in an ext2fs superblock, not
 * a kernel struct super_block.  This will allow us to call the feature-test
 * macros from user land. */
#define EXT2_SB(sb)     (sb)
#endif

/*
 * Maximal count of links to a file
 */
#define EXT2_LINK_MAX         65000

/*
 * Macro-instructions used to manage several block sizes
 */
#define EXT2_MIN_BLOCK_LOG_SIZE           10    /* 1024 */
#define EXT2_MAX_BLOCK_LOG_SIZE           16    /* 65536 */
#define EXT2_MIN_BLOCK_SIZE   (1 << EXT2_MIN_BLOCK_LOG_SIZE)
#define EXT2_MAX_BLOCK_SIZE   (1 << EXT2_MAX_BLOCK_LOG_SIZE)
#ifdef __KERNEL__
#define EXT2_BLOCK_SIZE(s)    ((s)->s_blocksize)
#define EXT2_BLOCK_SIZE_BITS(s)     ((s)->s_blocksize_bits)
#define EXT2_ADDR_PER_BLOCK_BITS(s) (EXT2_SB(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)
#else
#define EXT2_BLOCK_SIZE(s)    (EXT2_MIN_BLOCK_SIZE << (s)->s_log_block_size)
#define EXT2_BLOCK_SIZE_BITS(s)     ((s)->s_log_block_size + 10)
#define EXT2_INODE_SIZE(s)    (((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
                         EXT2_GOOD_OLD_INODE_SIZE : (s)->s_inode_size)
#define EXT2_FIRST_INO(s)     (((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
                         EXT2_GOOD_OLD_FIRST_INO : (s)->s_first_ino)
#endif
#define EXT2_ADDR_PER_BLOCK(s)      (EXT2_BLOCK_SIZE(s) / sizeof(__u32))

/*
 * Macro-instructions used to manage fragments
 */
#define EXT2_MIN_FRAG_SIZE          EXT2_MIN_BLOCK_SIZE
#define EXT2_MAX_FRAG_SIZE          EXT2_MAX_BLOCK_SIZE
#define EXT2_MIN_FRAG_LOG_SIZE            EXT2_MIN_BLOCK_LOG_SIZE
#ifdef __KERNEL__
# define EXT2_FRAG_SIZE(s)          (EXT2_SB(s)->s_frag_size)
# define EXT2_FRAGS_PER_BLOCK(s)    (EXT2_SB(s)->s_frags_per_block)
#else
# define EXT2_FRAG_SIZE(s)          (EXT2_MIN_FRAG_SIZE << (s)->s_log_frag_size)
# define EXT2_FRAGS_PER_BLOCK(s)    (EXT2_BLOCK_SIZE(s) / EXT2_FRAG_SIZE(s))
#endif

/*
 * ACL structures
 */
struct ext2_acl_header  /* Header of Access Control Lists */
{
      __u32 aclh_size;
      __u32 aclh_file_count;
      __u32 aclh_acle_count;
      __u32 aclh_first_acle;
};

struct ext2_acl_entry   /* Access Control List Entry */
{
      __u32 acle_size;
      __u16 acle_perms; /* Access permissions */
      __u16 acle_type;  /* Type of entry */
      __u16 acle_tag;   /* User or group identity */
      __u16 acle_pad1;
      __u32 acle_next;  /* Pointer on next entry for the */
                              /* same inode or on next free entry */
};

/*
 * Structure of a blocks group descriptor
 */
struct ext2_group_desc
{
      __u32 bg_block_bitmap;  /* Blocks bitmap block */
      __u32 bg_inode_bitmap;  /* Inodes bitmap block */
      __u32 bg_inode_table;         /* Inodes table block */
      __u16 bg_free_blocks_count;   /* Free blocks count */
      __u16 bg_free_inodes_count;   /* Free inodes count */
      __u16 bg_used_dirs_count;     /* Directories count */
      __u16 bg_flags;
      __u32 bg_reserved[2];
      __u16 bg_itable_unused; /* Unused inodes count */
      __u16 bg_checksum;            /* crc16(s_uuid+grouo_num+group_desc)*/
};

struct ext4_group_desc
{
      __u32 bg_block_bitmap;  /* Blocks bitmap block */
      __u32 bg_inode_bitmap;  /* Inodes bitmap block */
      __u32 bg_inode_table;         /* Inodes table block */
      __u16 bg_free_blocks_count;   /* Free blocks count */
      __u16 bg_free_inodes_count;   /* Free inodes count */
      __u16 bg_used_dirs_count;     /* Directories count */
      __u16 bg_flags;
      __u32 bg_reserved[2];
      __u16 bg_itable_unused; /* Unused inodes count */
      __u16 bg_checksum;            /* crc16(s_uuid+grouo_num+group_desc)*/
      __u32 bg_block_bitmap_hi;     /* Blocks bitmap block MSB */
      __u32 bg_inode_bitmap_hi;     /* Inodes bitmap block MSB */
      __u32 bg_inode_table_hi;      /* Inodes table block MSB */
      __u16 bg_free_blocks_count_hi;/* Free blocks count MSB */
      __u16 bg_free_inodes_count_hi;/* Free inodes count MSB */
      __u16 bg_used_dirs_count_hi;  /* Directories count MSB */
      __u16   bg_pad;
      __u32 bg_reserved2[3];
};

#define EXT2_BG_INODE_UNINIT  0x0001 /* Inode table/bitmap not initialized */
#define EXT2_BG_BLOCK_UNINIT  0x0002 /* Block bitmap not initialized */

/*
 * Data structures used by the directory indexing feature
 *
 * Note: all of the multibyte integer fields are little endian.
 */

/*
 * Note: dx_root_info is laid out so that if it should somehow get
 * overlaid by a dirent the two low bits of the hash version will be
 * zero.  Therefore, the hash version mod 4 should never be 0.
 * Sincerely, the paranoia department.
 */
struct ext2_dx_root_info {
      __u32 reserved_zero;
      __u8 hash_version; /* 0 now, 1 at release */
      __u8 info_length; /* 8 */
      __u8 indirect_levels;
      __u8 unused_flags;
};

#define EXT2_HASH_LEGACY            0
#define EXT2_HASH_HALF_MD4          1
#define EXT2_HASH_TEA               2
#define EXT2_HASH_LEGACY_UNSIGNED   3 /* reserved for userspace lib */
#define EXT2_HASH_HALF_MD4_UNSIGNED 4 /* reserved for userspace lib */
#define EXT2_HASH_TEA_UNSIGNED            5 /* reserved for userspace lib */

#define EXT2_HASH_FLAG_INCOMPAT     0x1

struct ext2_dx_entry {
      __u32 hash;
      __u32 block;
};

struct ext2_dx_countlimit {
      __u16 limit;
      __u16 count;
};


/*
 * Macro-instructions used to manage group descriptors
 */
#define EXT2_BLOCKS_PER_GROUP(s)    (EXT2_SB(s)->s_blocks_per_group)
#define EXT2_INODES_PER_GROUP(s)    (EXT2_SB(s)->s_inodes_per_group)
#define EXT2_INODES_PER_BLOCK(s)    (EXT2_BLOCK_SIZE(s)/EXT2_INODE_SIZE(s))
/* limits imposed by 16-bit value gd_free_{blocks,inode}_count */
#define EXT2_MAX_BLOCKS_PER_GROUP(s)      ((1 << 16) - 8)
#define EXT2_MAX_INODES_PER_GROUP(s)      ((1 << 16) - EXT2_INODES_PER_BLOCK(s))
#ifdef __KERNEL__
#define EXT2_DESC_PER_BLOCK(s)            (EXT2_SB(s)->s_desc_per_block)
#define EXT2_DESC_PER_BLOCK_BITS(s) (EXT2_SB(s)->s_desc_per_block_bits)
#else
#define EXT2_DESC_PER_BLOCK(s)            (EXT2_BLOCK_SIZE(s) / sizeof (struct ext2_group_desc))
#endif

/*
 * 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
 */
#define EXT2_SECRM_FL               0x00000001 /* Secure deletion */
#define EXT2_UNRM_FL                0x00000002 /* Undelete */
#define EXT2_COMPR_FL               0x00000004 /* Compress file */
#define EXT2_SYNC_FL                0x00000008 /* Synchronous updates */
#define EXT2_IMMUTABLE_FL           0x00000010 /* Immutable file */
#define EXT2_APPEND_FL              0x00000020 /* writes to file may only append */
#define EXT2_NODUMP_FL              0x00000040 /* do not dump file */
#define EXT2_NOATIME_FL             0x00000080 /* do not update atime */
/* Reserved for compression usage... */
#define EXT2_DIRTY_FL               0x00000100
#define EXT2_COMPRBLK_FL            0x00000200 /* One or more compressed clusters */
#define EXT2_NOCOMPR_FL             0x00000400 /* Access raw compressed data */
#define EXT2_ECOMPR_FL              0x00000800 /* Compression error */
/* End compression flags --- maybe not all used */
#define EXT2_BTREE_FL               0x00001000 /* btree format dir */
#define EXT2_INDEX_FL               0x00001000 /* hash-indexed directory */
#define EXT2_IMAGIC_FL              0x00002000
#define EXT3_JOURNAL_DATA_FL        0x00004000 /* file data should be journaled */
#define EXT2_NOTAIL_FL              0x00008000 /* file tail should not be merged */
#define EXT2_DIRSYNC_FL             0x00010000 /* Synchronous directory modifications */
#define EXT2_TOPDIR_FL              0x00020000 /* Top of directory hierarchies*/
#define EXT4_EXTENTS_FL             0x00080000 /* Inode uses extents */
#define EXT2_RESERVED_FL            0x80000000 /* reserved for ext2 lib */

#define EXT2_FL_USER_VISIBLE        0x000BDFFF /* User visible flags */
#define EXT2_FL_USER_MODIFIABLE           0x000080FF /* User modifiable flags */

/*
 * ioctl commands
 */

/* Used for online resize */
struct ext2_new_group_input {
      __u32 group;            /* Group number for this data */
      __u32 block_bitmap;     /* Absolute block number of block bitmap */
      __u32 inode_bitmap;     /* Absolute block number of inode bitmap */
      __u32 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;           /* Number of reserved GDT blocks in group */
};

#ifdef __GNU__                /* Needed for the Hurd */
#define _IOT_ext2_new_group_input _IOT (_IOTS(__u32), 5, _IOTS(__u16), 2, 0, 0)
#endif

#define EXT2_IOC_GETFLAGS           _IOR('f', 1, long)
#define EXT2_IOC_SETFLAGS           _IOW('f', 2, long)
#define EXT2_IOC_GETVERSION         _IOR('v', 1, long)
#define EXT2_IOC_SETVERSION         _IOW('v', 2, long)
#define EXT2_IOC_GETVERSION_NEW           _IOR('f', 3, long)
#define EXT2_IOC_SETVERSION_NEW           _IOW('f', 4, long)
#define EXT2_IOC_GROUP_EXTEND       _IOW('f', 7, unsigned long)
#define EXT2_IOC_GROUP_ADD          _IOW('f', 8,struct ext2_new_group_input)

/*
 * Structure of an inode on the disk
 */
struct ext2_inode {
      __u16 i_mode;           /* File mode */
      __u16 i_uid;            /* Low 16 bits of Owner Uid */
      __u32 i_size;           /* Size in bytes */
      __u32 i_atime;    /* Access time */
      __u32 i_ctime;    /* Inode change time */
      __u32 i_mtime;    /* Modification time */
      __u32 i_dtime;    /* Deletion Time */
      __u16 i_gid;            /* Low 16 bits of Group Id */
      __u16 i_links_count;    /* Links count */
      __u32 i_blocks;   /* Blocks count */
      __u32 i_flags;    /* File flags */
      union {
            struct {
                  __u32 l_i_version; /* was l_i_reserved1 */
            } linux1;
            struct {
                  __u32  h_i_translator;
            } hurd1;
            struct {
                  __u32  m_i_reserved1;
            } masix1;
      } osd1;                       /* OS dependent 1 */
      __u32 i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
      __u32 i_generation;     /* File version (for NFS) */
      __u32 i_file_acl; /* File ACL */
      __u32 i_dir_acl;  /* Directory ACL */
      __u32 i_faddr;    /* Fragment address */
      union {
            struct {
                  __u16 l_i_blocks_hi;
                  __u16 i_pad1;
                  __u16 l_i_uid_high;     /* these 2 fields    */
                  __u16 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 */
                  __u16 h_i_mode_high;
                  __u16 h_i_uid_high;
                  __u16 h_i_gid_high;
                  __u32 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 */
};

/*
 * Permanent part of an large inode on the disk
 */
struct ext2_inode_large {
      __u16 i_mode;           /* File mode */
      __u16 i_uid;            /* Low 16 bits of Owner Uid */
      __u32 i_size;           /* Size in bytes */
      __u32 i_atime;    /* Access time */
      __u32 i_ctime;    /* Inode Change time */
      __u32 i_mtime;    /* Modification time */
      __u32 i_dtime;    /* Deletion Time */
      __u16 i_gid;            /* Low 16 bits of Group Id */
      __u16 i_links_count;    /* Links count */
      __u32 i_blocks;   /* Blocks count */
      __u32 i_flags;    /* File flags */
      union {
            struct {
                  __u32 l_i_version; /* was l_i_reserved1 */
            } linux1;
            struct {
                  __u32  h_i_translator;
            } hurd1;
            struct {
                  __u32  m_i_reserved1;
            } masix1;
      } osd1;                       /* OS dependent 1 */
      __u32 i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
      __u32 i_generation;     /* File version (for NFS) */
      __u32 i_file_acl; /* File ACL */
      __u32 i_dir_acl;  /* Directory ACL */
      __u32 i_faddr;    /* Fragment address */
      union {
            struct {
                  __u16 l_i_blocks_hi;
                  __u16 i_pad1;
                  __u16 l_i_uid_high;     /* these 2 fields    */
                  __u16 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 */
                  __u16 h_i_mode_high;
                  __u16 h_i_uid_high;
                  __u16 h_i_gid_high;
                  __u32 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 */
      __u16 i_extra_isize;
      __u16 i_pad1;
      __u32 i_ctime_extra;    /* extra Change time (nsec << 2 | epoch) */
      __u32 i_mtime_extra;    /* extra Modification time (nsec << 2 | epoch) */
      __u32 i_atime_extra;    /* extra Access time (nsec << 2 | epoch) */
      __u32 i_crtime;   /* File creation time */
      __u32 i_crtime_extra;   /* extra File creation time (nsec << 2 | epoch)*/
};

#define i_size_high     i_dir_acl

#if defined(__KERNEL__) || defined(__linux__)
#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
#else
#if defined(__GNU__)

#define i_translator    osd1.hurd1.h_i_translator
#define i_frag          osd2.hurd2.h_i_frag;
#define i_fsize         osd2.hurd2.h_i_fsize;
#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

#else
#if defined(__masix__)

#define i_reserved1     osd1.masix1.m_i_reserved1
#define i_frag          osd2.masix2.m_i_frag
#define i_fsize         osd2.masix2.m_i_fsize
#define i_reserved2     osd2.masix2.m_i_reserved2

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

#if defined(__masix__)
#define inode_uid(inode)      ((inode).i_uid)
#define inode_gid(inode)      ((inode).i_gid)
#define ext2fs_set_i_uid_high(inode,x) (x)
#define ext2fs_set_i_gid_high(inode,x) (x)

#else
#define inode_uid(inode)      ((inode).i_uid | (inode).osd2.linux2.l_i_uid_high << 16)
#define inode_gid(inode)      ((inode).i_gid | (inode).osd2.linux2.l_i_gid_high << 16)
#define ext2fs_set_i_uid_high(inode,x) ((inode).osd2.linux2.l_i_uid_high = (x))
#define ext2fs_set_i_gid_high(inode,x) ((inode).osd2.linux2.l_i_gid_high = (x))
#endif

/*
 * File system states
 */
#define EXT2_VALID_FS               0x0001      /* Unmounted cleanly */
#define EXT2_ERROR_FS               0x0002      /* Errors detected */
#define EXT3_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      /* OK for use on development code */

/*
 * Mount flags
 */
#define EXT2_MOUNT_CHECK            0x0001      /* Do mount-time checks */
#define EXT2_MOUNT_GRPID            0x0004      /* Create files with directory's group */
#define EXT2_MOUNT_DEBUG            0x0008      /* Some debugging messages */
#define EXT2_MOUNT_ERRORS_CONT            0x0010      /* Continue on errors */
#define EXT2_MOUNT_ERRORS_RO        0x0020      /* Remount fs ro on errors */
#define EXT2_MOUNT_ERRORS_PANIC           0x0040      /* Panic on errors */
#define EXT2_MOUNT_MINIX_DF         0x0080      /* Mimics the Minix statfs */
#define EXT2_MOUNT_NO_UID32         0x0200  /* Disable 32-bit UIDs */

#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 {
      __u32 s_inodes_count;         /* Inodes count */
      __u32 s_blocks_count;         /* Blocks count */
      __u32 s_r_blocks_count; /* Reserved blocks count */
      __u32 s_free_blocks_count;    /* Free blocks count */
      __u32 s_free_inodes_count;    /* Free inodes count */
      __u32 s_first_data_block;     /* First Data Block */
      __u32 s_log_block_size; /* Block size */
      __s32 s_log_frag_size;  /* Fragment size */
      __u32 s_blocks_per_group;     /* # Blocks per group */
      __u32 s_frags_per_group;      /* # Fragments per group */
      __u32 s_inodes_per_group;     /* # Inodes per group */
      __u32 s_mtime;          /* Mount time */
      __u32 s_wtime;          /* Write time */
      __u16 s_mnt_count;            /* Mount count */
      __s16 s_max_mnt_count;  /* Maximal mount count */
      __u16 s_magic;          /* Magic signature */
      __u16 s_state;          /* File system state */
      __u16 s_errors;         /* Behaviour when detecting errors */
      __u16 s_minor_rev_level;      /* minor revision level */
      __u32 s_lastcheck;            /* time of last check */
      __u32 s_checkinterval;  /* max. time between checks */
      __u32 s_creator_os;           /* OS */
      __u32 s_rev_level;            /* Revision level */
      __u16 s_def_resuid;           /* Default uid for reserved blocks */
      __u16 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...
       */
      __u32 s_first_ino;            /* First non-reserved inode */
      __u16   s_inode_size;         /* size of inode structure */
      __u16 s_block_group_nr; /* block group # of this superblock */
      __u32 s_feature_compat; /* compatible feature set */
      __u32 s_feature_incompat;     /* incompatible feature set */
      __u32 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 */
      __u32 s_algorithm_usage_bitmap; /* For compression */
      /*
       * Performance hints.  Directory preallocation should only
       * happen if the EXT2_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 */
      __u16 s_reserved_gdt_blocks;  /* Per group table for online growth */
      /*
       * Journaling support valid if EXT2_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_jnl_backup_type;      /* Default type of journal backup */
      __u16 s_desc_size;            /* Group desc. size: INCOMPAT_64BIT */
      __u32 s_default_mount_opts;
      __u32 s_first_meta_bg;  /* First metablock group */
      __u32 s_mkfs_time;            /* When the filesystem was created */
      __u32 s_jnl_blocks[17];       /* Backup of the journal inode */
      __u32 s_blocks_count_hi;      /* Blocks count high 32bits */
      __u32 s_r_blocks_count_hi;    /* Reserved blocks count high 32 bits*/
      __u32 s_free_blocks_hi;       /* Free blocks count */
      __u16 s_min_extra_isize;      /* All inodes have at least # bytes */
      __u16 s_want_extra_isize;     /* New inodes should reserve # bytes */
      __u32 s_flags;          /* Miscellaneous flags */
      __u16   s_raid_stride;        /* RAID stride */
      __u16   s_mmp_interval;         /* # seconds to wait in MMP checking */
      __u64   s_mmp_block;            /* Block for multi-mount protection */
      __u32   s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/
      __u32   s_reserved[163];        /* 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

/*
 * Journal inode backup types
 */
#define EXT3_JNL_BACKUP_BLOCKS      1

/*
 * Feature set definitions
 */

#define EXT2_HAS_COMPAT_FEATURE(sb,mask)              \
      ( EXT2_SB(sb)->s_feature_compat & (mask) )
#define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)                 \
      ( EXT2_SB(sb)->s_feature_ro_compat & (mask) )
#define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)                  \
      ( EXT2_SB(sb)->s_feature_incompat & (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_INODE  0x0010
#define EXT2_FEATURE_COMPAT_DIR_INDEX           0x0020
#define EXT2_FEATURE_COMPAT_LAZY_BG       0x0040

#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER     0x0001
#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE 0x0002
/* #define EXT2_FEATURE_RO_COMPAT_BTREE_DIR     0x0004 not used */
#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 EXT2_FEATURE_INCOMPAT_COMPRESSION 0x0001
#define EXT2_FEATURE_INCOMPAT_FILETYPE          0x0002
#define EXT3_FEATURE_INCOMPAT_RECOVER           0x0004 /* Needs recovery */
#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008 /* Journal device */
#define EXT2_FEATURE_INCOMPAT_META_BG           0x0010
#define EXT3_FEATURE_INCOMPAT_EXTENTS           0x0040
#define EXT4_FEATURE_INCOMPAT_64BIT       0x0080
#define EXT4_FEATURE_INCOMPAT_MMP         0x0100


#define EXT2_FEATURE_COMPAT_SUPP    0
#define EXT2_FEATURE_INCOMPAT_SUPP  (EXT2_FEATURE_INCOMPAT_FILETYPE)
#define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                               EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
                               EXT2_FEATURE_RO_COMPAT_BTREE_DIR)

/*
 * 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
#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
 */
#define EXT2_NAME_LEN 255

struct ext2_dir_entry {
      __u32 inode;                  /* Inode number */
      __u16 rec_len;          /* Directory entry length */
      __u16 name_len;         /* Name length */
      char  name[EXT2_NAME_LEN];    /* File name */
};

/*
 * 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 {
      __u32 inode;                  /* Inode number */
      __u16 rec_len;          /* Directory entry length */
      __u8  name_len;         /* Name length */
      __u8  file_type;
      char  name[EXT2_NAME_LEN];    /* File name */
};

/*
 * Ext2 directory file types.  Only the low 3 bits are used.  The
 * other bits are reserved for now.
 */
#define EXT2_FT_UNKNOWN       0
#define EXT2_FT_REG_FILE      1
#define EXT2_FT_DIR           2
#define EXT2_FT_CHRDEV        3
#define EXT2_FT_BLKDEV        4
#define EXT2_FT_FIFO          5
#define EXT2_FT_SOCK          6
#define EXT2_FT_SYMLINK       7

#define EXT2_FT_MAX           8

/*
 * 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)

/*
 * 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.
 */
#define     EXT2_MMP_MAGIC    0x004D4D50 /* ASCII for MMP */
#define     EXT2_MMP_CLEAN    0xFF4D4D50 /* Value of mmp_seq for clean unmount */
#define     EXT2_MMP_FSCK_ON  0xE24D4D50 /* Value of mmp_seq when being fscked */

struct mmp_struct {
      __u32 mmp_magic;
      __u32 mmp_seq;
      __u64 mmp_time;
      char  mmp_nodename[64];
      char  mmp_bdevname[32];
      __u16 mmp_interval;
      __u16 mmp_pad1;
      __u32 mmp_pad2;
};

/*
 * Interval in number of seconds to update the MMP sequence number.
 */
#define EXT2_MMP_DEF_INTERVAL 5

#endif      /* _LINUX_EXT2_FS_H */

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