exportfs.h

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#ifndef LINUX_EXPORTFS_H
#define LINUX_EXPORTFS_H 1

#include <linux/types.h>

struct dentry;
struct inode;
struct super_block;
struct vfsmount;

/* limit the handle size to NFSv4 handle size now */
#define MAX_HANDLE_SZ 128

/*
 * The fileid_type identifies how the file within the filesystem is encoded.
 * In theory this is freely set and parsed by the filesystem, but we try to
 * stick to conventions so we can share some generic code and don't confuse
 * sniffers like ethereal/wireshark.
 *
 * The filesystem must not use the value '0' or '0xff'.
 */
enum fid_type {
    /*
     * The root, or export point, of the filesystem.
     * (Never actually passed down to the filesystem.
     */
    FILEID_ROOT = 0,

    /*
     * 32bit inode number, 32 bit generation number.
     */
    FILEID_INO32_GEN = 1,

    /*
     * 32bit inode number, 32 bit generation number,
     * 32 bit parent directory inode number.
     */
    FILEID_INO32_GEN_PARENT = 2,

    /*
     * 64 bit object ID, 64 bit root object ID,
     * 32 bit generation number.
     */
    FILEID_BTRFS_WITHOUT_PARENT = 0x4d,

    /*
     * 64 bit object ID, 64 bit root object ID,
     * 32 bit generation number,
     * 64 bit parent object ID, 32 bit parent generation.
     */
    FILEID_BTRFS_WITH_PARENT = 0x4e,

    /*
     * 64 bit object ID, 64 bit root object ID,
     * 32 bit generation number,
     * 64 bit parent object ID, 32 bit parent generation,
     * 64 bit parent root object ID.
     */
    FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,

    /*
     * 32 bit block number, 16 bit partition reference,
     * 16 bit unused, 32 bit generation number.
     */
    FILEID_UDF_WITHOUT_PARENT = 0x51,

    /*
     * 32 bit block number, 16 bit partition reference,
     * 16 bit unused, 32 bit generation number,
     * 32 bit parent block number, 32 bit parent generation number
     */
    FILEID_UDF_WITH_PARENT = 0x52,

    /*
     * 64 bit checkpoint number, 64 bit inode number,
     * 32 bit generation number.
     */
    FILEID_NILFS_WITHOUT_PARENT = 0x61,

    /*
     * 64 bit checkpoint number, 64 bit inode number,
     * 32 bit generation number, 32 bit parent generation.
     * 64 bit parent inode number.
     */
    FILEID_NILFS_WITH_PARENT = 0x62,
};

struct fid {
    union {
        struct {
            u32 ino;
            u32 gen;
            u32 parent_ino;
            u32 parent_gen;
        } i32;
        struct {
            u32 block;
            u16 partref;
            u16 parent_partref;
            u32 generation;
            u32 parent_block;
            u32 parent_generation;
        } udf;
        __u32 raw[0];
    };
};

struct export_operations {
    int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
            struct inode *parent);
    struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
            int fh_len, int fh_type);
    struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
            int fh_len, int fh_type);
    int (*get_name)(struct dentry *parent, char *name,
            struct dentry *child);
    struct dentry * (*get_parent)(struct dentry *child);
    int (*commit_metadata)(struct inode *inode);
};

extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
    int *max_len, int connectable);
extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
    int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
    void *context);

/*
 * Generic helpers for filesystems.
 */
extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
    struct fid *fid, int fh_len, int fh_type,
    struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
extern struct dentry *generic_fh_to_parent(struct super_block *sb,
    struct fid *fid, int fh_len, int fh_type,
    struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));

#endif /* LINUX_EXPORTFS_H */