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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 * 64 bit object ID, 64 bit root object ID,
39 * 32 bit generation number.
40 */
41 FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
42
43 /*
44 * 64 bit object ID, 64 bit root object ID,
45 * 32 bit generation number,
46 * 64 bit parent object ID, 32 bit parent generation.
47 */
48 FILEID_BTRFS_WITH_PARENT = 0x4e,
49
50 /*
51 * 64 bit object ID, 64 bit root object ID,
52 * 32 bit generation number,
53 * 64 bit parent object ID, 32 bit parent generation,
54 * 64 bit parent root object ID.
55 */
56 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
57
58 /*
59 * 32 bit block number, 16 bit partition reference,
60 * 16 bit unused, 32 bit generation number.
61 */
62 FILEID_UDF_WITHOUT_PARENT = 0x51,
63
64 /*
65 * 32 bit block number, 16 bit partition reference,
66 * 16 bit unused, 32 bit generation number,
67 * 32 bit parent block number, 32 bit parent generation number
68 */
69 FILEID_UDF_WITH_PARENT = 0x52,
70
71 /*
72 * 64 bit checkpoint number, 64 bit inode number,
73 * 32 bit generation number.
74 */
75 FILEID_NILFS_WITHOUT_PARENT = 0x61,
76
77 /*
78 * 64 bit checkpoint number, 64 bit inode number,
79 * 32 bit generation number, 32 bit parent generation.
80 * 64 bit parent inode number.
81 */
82 FILEID_NILFS_WITH_PARENT = 0x62,
83};
84
85struct fid {
86 union {
87 struct {
88 u32 ino;
89 u32 gen;
90 u32 parent_ino;
91 u32 parent_gen;
92 } i32;
93 struct {
94 u32 block;
95 u16 partref;
96 u16 parent_partref;
97 u32 generation;
98 u32 parent_block;
99 u32 parent_generation;
100 } udf;
101 __u32 raw[0];
102 };
103};
104
105/**
106 * struct export_operations - for nfsd to communicate with file systems
107 * @encode_fh: encode a file handle fragment from a dentry
108 * @fh_to_dentry: find the implied object and get a dentry for it
109 * @fh_to_parent: find the implied object's parent and get a dentry for it
110 * @get_name: find the name for a given inode in a given directory
111 * @get_parent: find the parent of a given directory
112 * @commit_metadata: commit metadata changes to stable storage
113 *
114 * See Documentation/filesystems/nfs/Exporting for details on how to use
115 * this interface correctly.
116 *
117 * encode_fh:
118 * @encode_fh should store in the file handle fragment @fh (using at most
119 * @max_len bytes) information that can be used by @decode_fh to recover the
120 * file refered to by the &struct dentry @de. If the @connectable flag is
121 * set, the encode_fh() should store sufficient information so that a good
122 * attempt can be made to find not only the file but also it's place in the
123 * filesystem. This typically means storing a reference to de->d_parent in
124 * the filehandle fragment. encode_fh() should return the number of bytes
125 * stored or a negative error code such as %-ENOSPC
126 *
127 * fh_to_dentry:
128 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
129 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
130 * to the same file that the file handle fragment refers to. If it cannot,
131 * it should return a %NULL pointer if the file was found but no acceptable
132 * &dentries were available, or an %ERR_PTR error code indicating why it
133 * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be
134 * returned including, if necessary, a new dentry created with d_alloc_root.
135 * The caller can then find any other extant dentries by following the
136 * d_alias links.
137 *
138 * fh_to_parent:
139 * Same as @fh_to_dentry, except that it returns a pointer to the parent
140 * dentry if it was encoded into the filehandle fragment by @encode_fh.
141 *
142 * get_name:
143 * @get_name should find a name for the given @child in the given @parent
144 * directory. The name should be stored in the @name (with the
145 * understanding that it is already pointing to a a %NAME_MAX+1 sized
146 * buffer. get_name() should return %0 on success, a negative error code
147 * or error. @get_name will be called without @parent->i_mutex held.
148 *
149 * get_parent:
150 * @get_parent should find the parent directory for the given @child which
151 * is also a directory. In the event that it cannot be found, or storage
152 * space cannot be allocated, a %ERR_PTR should be returned.
153 *
154 * commit_metadata:
155 * @commit_metadata should commit metadata changes to stable storage.
156 *
157 * Locking rules:
158 * get_parent is called with child->d_inode->i_mutex down
159 * get_name is not (which is possibly inconsistent)
160 */
161
162struct export_operations {
163 int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
164 int connectable);
165 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
166 int fh_len, int fh_type);
167 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
168 int fh_len, int fh_type);
169 int (*get_name)(struct dentry *parent, char *name,
170 struct dentry *child);
171 struct dentry * (*get_parent)(struct dentry *child);
172 int (*commit_metadata)(struct inode *inode);
173};
174
175extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
176 int *max_len, int connectable);
177extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
178 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
179 void *context);
180
181/*
182 * Generic helpers for filesystems.
183 */
184extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
185 struct fid *fid, int fh_len, int fh_type,
186 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
187extern struct dentry *generic_fh_to_parent(struct super_block *sb,
188 struct fid *fid, int fh_len, int fh_type,
189 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
190
191#endif /* LINUX_EXPORTFS_H */