/* SPDX-License-Identifier: GPL-2.0 */
#ifndef LINUX_EXPORTFS_H
#define LINUX_EXPORTFS_H 1
#include <linux/types.h>
struct dentry;
struct iattr;
struct inode;
struct iomap;
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,
/*
* 32 bit generation number, 40 bit i_pos.
*/
FILEID_FAT_WITHOUT_PARENT = 0x71,
/*
* 32 bit generation number, 40 bit i_pos,
* 32 bit parent generation number, 40 bit parent i_pos
*/
FILEID_FAT_WITH_PARENT = 0x72,
/*
* 128 bit child FID (struct lu_fid)
* 128 bit parent FID (struct lu_fid)
*/
FILEID_LUSTRE = 0x97,
/*
* Filesystems must not use 0xff file ID.
*/
FILEID_INVALID = 0xff,
};
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 - for nfsd to communicate with file systems
* @encode_fh: encode a file handle fragment from a dentry
* @fh_to_dentry: find the implied object and get a dentry for it
* @fh_to_parent: find the implied object's parent and get a dentry for it
* @get_name: find the name for a given inode in a given directory
* @get_parent: find the parent of a given directory
* @commit_metadata: commit metadata changes to stable storage
*
* See Documentation/filesystems/nfs/exporting.rst for details on how to use
* this interface correctly.
*
* encode_fh:
* @encode_fh should store in the file handle fragment @fh (using at most
* @max_len bytes) information that can be used by @decode_fh to recover the
* file referred to by the &struct dentry @de. If the @connectable flag is
* set, the encode_fh() should store sufficient information so that a good
* attempt can be made to find not only the file but also it's place in the
* filesystem. This typically means storing a reference to de->d_parent in
* the filehandle fragment. encode_fh() should return the fileid_type on
* success and on error returns 255 (if the space needed to encode fh is
* greater than @max_len*4 bytes). On error @max_len contains the minimum
* size(in 4 byte unit) needed to encode the file handle.
*
* fh_to_dentry:
* @fh_to_dentry is given a &struct super_block (@sb) and a file handle
* fragment (@fh, @fh_len). It should return a &struct dentry which refers
* to the same file that the file handle fragment refers to. If it cannot,
* it should return a %NULL pointer if the file cannot be found, or an
* %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
* Any other error code is treated like %NULL, and will cause an %ESTALE error
* for callers of exportfs_decode_fh().
* Any suitable dentry can be returned including, if necessary, a new dentry
* created with d_alloc_root. The caller can then find any other extant
* dentries by following the d_alias links.
*
* fh_to_parent:
* Same as @fh_to_dentry, except that it returns a pointer to the parent
* dentry if it was encoded into the filehandle fragment by @encode_fh.
*
* get_name:
* @get_name should find a name for the given @child in the given @parent
* directory. The name should be stored in the @name (with the
* understanding that it is already pointing to a a %NAME_MAX+1 sized
* buffer. get_name() should return %0 on success, a negative error code
* or error. @get_name will be called without @parent->i_mutex held.
*
* get_parent:
* @get_parent should find the parent directory for the given @child which
* is also a directory. In the event that it cannot be found, or storage
* space cannot be allocated, a %ERR_PTR should be returned.
*
* commit_metadata:
* @commit_metadata should commit metadata changes to stable storage.
*
* Locking rules:
* get_parent is called with child->d_inode->i_mutex down
* get_name is not (which is possibly inconsistent)
*/
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);
int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
int (*map_blocks)(struct inode *inode, loff_t offset,
u64 len, struct iomap *iomap,
bool write, u32 *device_generation);
int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
int nr_iomaps, struct iattr *iattr);
};
extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
int *max_len, struct inode *parent);
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 */