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1#ifndef LINUX_EXPORTFS_H
2#define LINUX_EXPORTFS_H 1
3
4#include <linux/types.h>
5
6struct dentry;
7struct inode;
8struct super_block;
9struct vfsmount;
10
11/*
12 * The fileid_type identifies how the file within the filesystem is encoded.
13 * In theory this is freely set and parsed by the filesystem, but we try to
14 * stick to conventions so we can share some generic code and don't confuse
15 * sniffers like ethereal/wireshark.
16 *
17 * The filesystem must not use the value '0' or '0xff'.
18 */
19enum fid_type {
20 /*
21 * The root, or export point, of the filesystem.
22 * (Never actually passed down to the filesystem.
23 */
24 FILEID_ROOT = 0,
25
26 /*
27 * 32bit inode number, 32 bit generation number.
28 */
29 FILEID_INO32_GEN = 1,
30
31 /*
32 * 32bit inode number, 32 bit generation number,
33 * 32 bit parent directory inode number.
34 */
35 FILEID_INO32_GEN_PARENT = 2,
36
37 /*
38 * 32 bit block number, 16 bit partition reference,
39 * 16 bit unused, 32 bit generation number.
40 */
41 FILEID_UDF_WITHOUT_PARENT = 0x51,
42
43 /*
44 * 32 bit block number, 16 bit partition reference,
45 * 16 bit unused, 32 bit generation number,
46 * 32 bit parent block number, 32 bit parent generation number
47 */
48 FILEID_UDF_WITH_PARENT = 0x52,
49};
50
51struct fid {
52 union {
53 struct {
54 u32 ino;
55 u32 gen;
56 u32 parent_ino;
57 u32 parent_gen;
58 } i32;
59 struct {
60 u32 block;
61 u16 partref;
62 u16 parent_partref;
63 u32 generation;
64 u32 parent_block;
65 u32 parent_generation;
66 } udf;
67 __u32 raw[0];
68 };
69};
70
71/**
72 * struct export_operations - for nfsd to communicate with file systems
73 * @encode_fh: encode a file handle fragment from a dentry
74 * @fh_to_dentry: find the implied object and get a dentry for it
75 * @fh_to_parent: find the implied object's parent and get a dentry for it
76 * @get_name: find the name for a given inode in a given directory
77 * @get_parent: find the parent of a given directory
78 *
79 * See Documentation/filesystems/Exporting for details on how to use
80 * this interface correctly.
81 *
82 * encode_fh:
83 * @encode_fh should store in the file handle fragment @fh (using at most
84 * @max_len bytes) information that can be used by @decode_fh to recover the
85 * file refered to by the &struct dentry @de. If the @connectable flag is
86 * set, the encode_fh() should store sufficient information so that a good
87 * attempt can be made to find not only the file but also it's place in the
88 * filesystem. This typically means storing a reference to de->d_parent in
89 * the filehandle fragment. encode_fh() should return the number of bytes
90 * stored or a negative error code such as %-ENOSPC
91 *
92 * fh_to_dentry:
93 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
94 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
95 * to the same file that the file handle fragment refers to. If it cannot,
96 * it should return a %NULL pointer if the file was found but no acceptable
97 * &dentries were available, or an %ERR_PTR error code indicating why it
98 * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be
99 * returned including, if necessary, a new dentry created with d_alloc_root.
100 * The caller can then find any other extant dentries by following the
101 * d_alias links.
102 *
103 * fh_to_parent:
104 * Same as @fh_to_dentry, except that it returns a pointer to the parent
105 * dentry if it was encoded into the filehandle fragment by @encode_fh.
106 *
107 * get_name:
108 * @get_name should find a name for the given @child in the given @parent
109 * directory. The name should be stored in the @name (with the
110 * understanding that it is already pointing to a a %NAME_MAX+1 sized
111 * buffer. get_name() should return %0 on success, a negative error code
112 * or error. @get_name will be called without @parent->i_mutex held.
113 *
114 * get_parent:
115 * @get_parent should find the parent directory for the given @child which
116 * is also a directory. In the event that it cannot be found, or storage
117 * space cannot be allocated, a %ERR_PTR should be returned.
118 *
119 * Locking rules:
120 * get_parent is called with child->d_inode->i_mutex down
121 * get_name is not (which is possibly inconsistent)
122 */
123
124struct export_operations {
125 int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
126 int connectable);
127 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
128 int fh_len, int fh_type);
129 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
130 int fh_len, int fh_type);
131 int (*get_name)(struct dentry *parent, char *name,
132 struct dentry *child);
133 struct dentry * (*get_parent)(struct dentry *child);
134};
135
136extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
137 int *max_len, int connectable);
138extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
139 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
140 void *context);
141
142/*
143 * Generic helpers for filesystems.
144 */
145extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
146 struct fid *fid, int fh_len, int fh_type,
147 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
148extern struct dentry *generic_fh_to_parent(struct super_block *sb,
149 struct fid *fid, int fh_len, int fh_type,
150 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
151
152#endif /* LINUX_EXPORTFS_H */