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marcus.erl |
#ifndef LINUX_EXPORTFS_H
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#define LINUX_EXPORTFS_H 1
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#include <linux/types.h>
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struct dentry;
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struct inode;
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struct super_block;
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struct vfsmount;
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/*
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* The fileid_type identifies how the file within the filesystem is encoded.
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* In theory this is freely set and parsed by the filesystem, but we try to
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* stick to conventions so we can share some generic code and don't confuse
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* sniffers like ethereal/wireshark.
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*
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* The filesystem must not use the value '0' or '0xff'.
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*/
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enum fid_type {
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/*
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* The root, or export point, of the filesystem.
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* (Never actually passed down to the filesystem.
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*/
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FILEID_ROOT = 0,
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/*
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* 32bit inode number, 32 bit generation number.
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*/
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FILEID_INO32_GEN = 1,
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/*
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* 32bit inode number, 32 bit generation number,
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* 32 bit parent directory inode number.
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*/
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FILEID_INO32_GEN_PARENT = 2,
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};
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struct fid {
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union {
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struct {
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u32 ino;
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u32 gen;
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u32 parent_ino;
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u32 parent_gen;
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} i32;
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__u32 raw[6];
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};
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};
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/**
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* struct export_operations - for nfsd to communicate with file systems
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* @decode_fh: decode a file handle fragment and return a &struct dentry
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* @encode_fh: encode a file handle fragment from a dentry
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* @get_name: find the name for a given inode in a given directory
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* @get_parent: find the parent of a given directory
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* @get_dentry: find a dentry for the inode given a file handle sub-fragment
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*
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* See Documentation/filesystems/Exporting for details on how to use
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* this interface correctly.
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*
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* encode_fh:
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* @encode_fh should store in the file handle fragment @fh (using at most
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* @max_len bytes) information that can be used by @decode_fh to recover the
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* file refered to by the &struct dentry @de. If the @connectable flag is
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* set, the encode_fh() should store sufficient information so that a good
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* attempt can be made to find not only the file but also it's place in the
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* filesystem. This typically means storing a reference to de->d_parent in
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* the filehandle fragment. encode_fh() should return the number of bytes
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* stored or a negative error code such as %-ENOSPC
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*
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* fh_to_dentry:
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* @fh_to_dentry is given a &struct super_block (@sb) and a file handle
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* fragment (@fh, @fh_len). It should return a &struct dentry which refers
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* to the same file that the file handle fragment refers to. If it cannot,
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* it should return a %NULL pointer if the file was found but no acceptable
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* &dentries were available, or an %ERR_PTR error code indicating why it
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* couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be
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* returned including, if necessary, a new dentry created with d_alloc_root.
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* The caller can then find any other extant dentries by following the
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* d_alias links.
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*
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* fh_to_parent:
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* Same as @fh_to_dentry, except that it returns a pointer to the parent
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* dentry if it was encoded into the filehandle fragment by @encode_fh.
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*
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* get_name:
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* @get_name should find a name for the given @child in the given @parent
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* directory. The name should be stored in the @name (with the
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* understanding that it is already pointing to a a %NAME_MAX+1 sized
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* buffer. get_name() should return %0 on success, a negative error code
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* or error. @get_name will be called without @parent->i_mutex held.
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*
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* get_parent:
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* @get_parent should find the parent directory for the given @child which
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* is also a directory. In the event that it cannot be found, or storage
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* space cannot be allocated, a %ERR_PTR should be returned.
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*
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* Locking rules:
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* get_parent is called with child->d_inode->i_mutex down
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* get_name is not (which is possibly inconsistent)
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*/
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struct export_operations {
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int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
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int connectable);
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struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type);
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struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type);
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int (*get_name)(struct dentry *parent, char *name,
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struct dentry *child);
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struct dentry * (*get_parent)(struct dentry *child);
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};
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extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
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int *max_len, int connectable);
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extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
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int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
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void *context);
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/*
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* Generic helpers for filesystems.
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*/
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extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
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struct fid *fid, int fh_len, int fh_type,
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struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
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extern struct dentry *generic_fh_to_parent(struct super_block *sb,
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struct fid *fid, int fh_len, int fh_type,
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struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
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#endif /* LINUX_EXPORTFS_H */
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