#ifndef LINUX_EXPORTFS_H #define LINUX_EXPORTFS_H 1 #include <linux/types.h> struct dentry; struct inode; struct super_block; struct vfsmount; /* * 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, }; struct fid { union { struct { u32 ino; u32 gen; u32 parent_ino; u32 parent_gen; } i32; __u32 raw[6]; }; }; /** * struct export_operations - for nfsd to communicate with file systems * @decode_fh: decode a file handle fragment and return a &struct dentry * @encode_fh: encode a file handle fragment from a dentry * @get_name: find the name for a given inode in a given directory * @get_parent: find the parent of a given directory * @get_dentry: find a dentry for the inode given a file handle sub-fragment * * See Documentation/filesystems/Exporting 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 refered 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 number of bytes * stored or a negative error code such as %-ENOSPC * * 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 was found but no acceptable * &dentries were available, or an %ERR_PTR error code indicating why it * couldn't be found (e.g. %ENOENT or %ENOMEM). 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. * * 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 dentry *de, __u32 *fh, int *max_len, int connectable); 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); }; 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 */