/* SPDX-License-Identifier: GPL-2.0 */
/*
 * 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
 */
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/blockgroup_lock.h>
#include <linux/percpu_counter.h>
#include <linux/rbtree.h>
#include <linux/mm.h>
#include <linux/highmem.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 is the physical block number of the block which was most-recently
         * allocated to this file.  This gives 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

struct mb_cache;

/*
 * second extended-fs super-block data in memory
 */
struct ext2_sb_info {
        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_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;
        struct mb_cache *s_ea_block_cache;
        struct dax_device *s_daxdev;
        u64 s_dax_part_off;
};

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             65536
#define EXT2_MIN_BLOCK_LOG_SIZE           10
#define EXT2_MAX_BLOCK_LOG_SIZE           16
#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)

/*
 * 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_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_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_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_ERRORS_MASK          0x000070
#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  /* Obsolete, use DAX */
#define EXT2_MOUNT_USRQUOTA             0x020000  /* user quota */
#define EXT2_MOUNT_GRPQUOTA             0x040000  /* group quota */
#define EXT2_MOUNT_RESERVATION          0x080000  /* Preallocation */
#define EXT2_MOUNT_DAX                  0x100000  /* Direct Access */


#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

/*
 * Allocation flags
 */
#define EXT2_ALLOC_NORESERVE            0x1     /* Do not use reservation
                                                 * window for allocation */

/*
 * 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_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 */
#ifdef CONFIG_QUOTA
        struct dquot __rcu *i_dquot[MAXQUOTAS];
#endif
};

/*
 * 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_blocks(struct inode *, ext2_fsblk_t,
                                unsigned long *, int *, unsigned int);
extern int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
                                 unsigned int count);
extern void ext2_free_blocks(struct inode *, ext2_fsblk_t, unsigned long);
extern unsigned long ext2_count_free_blocks (struct super_block *);
extern unsigned long ext2_count_dirs (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 */
int ext2_add_link(struct dentry *, struct inode *);
int ext2_inode_by_name(struct inode *dir,
                              const struct qstr *child, ino_t *ino);
int ext2_make_empty(struct inode *, struct inode *);
struct ext2_dir_entry_2 *ext2_find_entry(struct inode *, const struct qstr *,
                struct folio **foliop);
int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct folio *folio);
int ext2_empty_dir(struct inode *);
struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct folio **foliop);
int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
                struct folio *folio, struct inode *inode, bool update_times);

/* 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 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 *);
void ext2_write_failed(struct address_space *mapping, loff_t to);
extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
extern int ext2_setattr (struct mnt_idmap *, struct dentry *, struct iattr *);
extern int ext2_getattr (struct mnt_idmap *, const struct path *,
                         struct kstat *, u32, unsigned int);
extern void ext2_set_inode_flags(struct inode *inode);
extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                       u64 start, u64 len);

/* ioctl.c */
extern int ext2_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
extern int ext2_fileattr_set(struct mnt_idmap *idmap,
                             struct dentry *dentry, struct file_kattr *fa);
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_sync_super(struct super_block *sb, struct ext2_super_block *es,
                            int wait);

/*
 * 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;

/* inode.c */
extern void ext2_set_file_ops(struct inode *inode);
extern const struct address_space_operations ext2_aops;
extern const struct iomap_ops ext2_iomap_ops;

/* 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);
}

static inline ext2_fsblk_t
ext2_group_last_block_no(struct super_block *sb, unsigned long group_no)
{
        struct ext2_sb_info *sbi = EXT2_SB(sb);

        if (group_no == sbi->s_groups_count - 1)
                return le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
        else
                return ext2_group_first_block_no(sb, group_no) +
                        EXT2_BLOCKS_PER_GROUP(sb) - 1;
}

#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