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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/* limit the handle size to NFSv4 handle size now */
12#define MAX_HANDLE_SZ 128
13
14/*
15 * The fileid_type identifies how the file within the filesystem is encoded.
16 * In theory this is freely set and parsed by the filesystem, but we try to
17 * stick to conventions so we can share some generic code and don't confuse
18 * sniffers like ethereal/wireshark.
19 *
20 * The filesystem must not use the value '0' or '0xff'.
21 */
22enum fid_type {
23 /*
24 * The root, or export point, of the filesystem.
25 * (Never actually passed down to the filesystem.
26 */
27 FILEID_ROOT = 0,
28
29 /*
30 * 32bit inode number, 32 bit generation number.
31 */
32 FILEID_INO32_GEN = 1,
33
34 /*
35 * 32bit inode number, 32 bit generation number,
36 * 32 bit parent directory inode number.
37 */
38 FILEID_INO32_GEN_PARENT = 2,
39
40 /*
41 * 64 bit object ID, 64 bit root object ID,
42 * 32 bit generation number.
43 */
44 FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
45
46 /*
47 * 64 bit object ID, 64 bit root object ID,
48 * 32 bit generation number,
49 * 64 bit parent object ID, 32 bit parent generation.
50 */
51 FILEID_BTRFS_WITH_PARENT = 0x4e,
52
53 /*
54 * 64 bit object ID, 64 bit root object ID,
55 * 32 bit generation number,
56 * 64 bit parent object ID, 32 bit parent generation,
57 * 64 bit parent root object ID.
58 */
59 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
60
61 /*
62 * 32 bit block number, 16 bit partition reference,
63 * 16 bit unused, 32 bit generation number.
64 */
65 FILEID_UDF_WITHOUT_PARENT = 0x51,
66
67 /*
68 * 32 bit block number, 16 bit partition reference,
69 * 16 bit unused, 32 bit generation number,
70 * 32 bit parent block number, 32 bit parent generation number
71 */
72 FILEID_UDF_WITH_PARENT = 0x52,
73
74 /*
75 * 64 bit checkpoint number, 64 bit inode number,
76 * 32 bit generation number.
77 */
78 FILEID_NILFS_WITHOUT_PARENT = 0x61,
79
80 /*
81 * 64 bit checkpoint number, 64 bit inode number,
82 * 32 bit generation number, 32 bit parent generation.
83 * 64 bit parent inode number.
84 */
85 FILEID_NILFS_WITH_PARENT = 0x62,
86
87 /*
88 * Filesystems must not use 0xff file ID.
89 */
90 FILEID_INVALID = 0xff,
91};
92
93struct fid {
94 union {
95 struct {
96 u32 ino;
97 u32 gen;
98 u32 parent_ino;
99 u32 parent_gen;
100 } i32;
101 struct {
102 u32 block;
103 u16 partref;
104 u16 parent_partref;
105 u32 generation;
106 u32 parent_block;
107 u32 parent_generation;
108 } udf;
109 __u32 raw[0];
110 };
111};
112
113/**
114 * struct export_operations - for nfsd to communicate with file systems
115 * @encode_fh: encode a file handle fragment from a dentry
116 * @fh_to_dentry: find the implied object and get a dentry for it
117 * @fh_to_parent: find the implied object's parent and get a dentry for it
118 * @get_name: find the name for a given inode in a given directory
119 * @get_parent: find the parent of a given directory
120 * @commit_metadata: commit metadata changes to stable storage
121 *
122 * See Documentation/filesystems/nfs/Exporting for details on how to use
123 * this interface correctly.
124 *
125 * encode_fh:
126 * @encode_fh should store in the file handle fragment @fh (using at most
127 * @max_len bytes) information that can be used by @decode_fh to recover the
128 * file referred to by the &struct dentry @de. If the @connectable flag is
129 * set, the encode_fh() should store sufficient information so that a good
130 * attempt can be made to find not only the file but also it's place in the
131 * filesystem. This typically means storing a reference to de->d_parent in
132 * the filehandle fragment. encode_fh() should return the fileid_type on
133 * success and on error returns 255 (if the space needed to encode fh is
134 * greater than @max_len*4 bytes). On error @max_len contains the minimum
135 * size(in 4 byte unit) needed to encode the file handle.
136 *
137 * fh_to_dentry:
138 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
139 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
140 * to the same file that the file handle fragment refers to. If it cannot,
141 * it should return a %NULL pointer if the file was found but no acceptable
142 * &dentries were available, or an %ERR_PTR error code indicating why it
143 * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be
144 * returned including, if necessary, a new dentry created with d_alloc_root.
145 * The caller can then find any other extant dentries by following the
146 * d_alias links.
147 *
148 * fh_to_parent:
149 * Same as @fh_to_dentry, except that it returns a pointer to the parent
150 * dentry if it was encoded into the filehandle fragment by @encode_fh.
151 *
152 * get_name:
153 * @get_name should find a name for the given @child in the given @parent
154 * directory. The name should be stored in the @name (with the
155 * understanding that it is already pointing to a a %NAME_MAX+1 sized
156 * buffer. get_name() should return %0 on success, a negative error code
157 * or error. @get_name will be called without @parent->i_mutex held.
158 *
159 * get_parent:
160 * @get_parent should find the parent directory for the given @child which
161 * is also a directory. In the event that it cannot be found, or storage
162 * space cannot be allocated, a %ERR_PTR should be returned.
163 *
164 * commit_metadata:
165 * @commit_metadata should commit metadata changes to stable storage.
166 *
167 * Locking rules:
168 * get_parent is called with child->d_inode->i_mutex down
169 * get_name is not (which is possibly inconsistent)
170 */
171
172struct export_operations {
173 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
174 struct inode *parent);
175 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
176 int fh_len, int fh_type);
177 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
178 int fh_len, int fh_type);
179 int (*get_name)(struct dentry *parent, char *name,
180 struct dentry *child);
181 struct dentry * (*get_parent)(struct dentry *child);
182 int (*commit_metadata)(struct inode *inode);
183};
184
185extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
186 int *max_len, struct inode *parent);
187extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
188 int *max_len, int connectable);
189extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
190 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
191 void *context);
192
193/*
194 * Generic helpers for filesystems.
195 */
196extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
197 struct fid *fid, int fh_len, int fh_type,
198 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
199extern struct dentry *generic_fh_to_parent(struct super_block *sb,
200 struct fid *fid, int fh_len, int fh_type,
201 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
202
203#endif /* LINUX_EXPORTFS_H */