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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 iattr;
8struct inode;
9struct iomap;
10struct super_block;
11struct vfsmount;
12
13/* limit the handle size to NFSv4 handle size now */
14#define MAX_HANDLE_SZ 128
15
16/*
17 * The fileid_type identifies how the file within the filesystem is encoded.
18 * In theory this is freely set and parsed by the filesystem, but we try to
19 * stick to conventions so we can share some generic code and don't confuse
20 * sniffers like ethereal/wireshark.
21 *
22 * The filesystem must not use the value '0' or '0xff'.
23 */
24enum fid_type {
25 /*
26 * The root, or export point, of the filesystem.
27 * (Never actually passed down to the filesystem.
28 */
29 FILEID_ROOT = 0,
30
31 /*
32 * 32bit inode number, 32 bit generation number.
33 */
34 FILEID_INO32_GEN = 1,
35
36 /*
37 * 32bit inode number, 32 bit generation number,
38 * 32 bit parent directory inode number.
39 */
40 FILEID_INO32_GEN_PARENT = 2,
41
42 /*
43 * 64 bit object ID, 64 bit root object ID,
44 * 32 bit generation number.
45 */
46 FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
47
48 /*
49 * 64 bit object ID, 64 bit root object ID,
50 * 32 bit generation number,
51 * 64 bit parent object ID, 32 bit parent generation.
52 */
53 FILEID_BTRFS_WITH_PARENT = 0x4e,
54
55 /*
56 * 64 bit object ID, 64 bit root object ID,
57 * 32 bit generation number,
58 * 64 bit parent object ID, 32 bit parent generation,
59 * 64 bit parent root object ID.
60 */
61 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
62
63 /*
64 * 32 bit block number, 16 bit partition reference,
65 * 16 bit unused, 32 bit generation number.
66 */
67 FILEID_UDF_WITHOUT_PARENT = 0x51,
68
69 /*
70 * 32 bit block number, 16 bit partition reference,
71 * 16 bit unused, 32 bit generation number,
72 * 32 bit parent block number, 32 bit parent generation number
73 */
74 FILEID_UDF_WITH_PARENT = 0x52,
75
76 /*
77 * 64 bit checkpoint number, 64 bit inode number,
78 * 32 bit generation number.
79 */
80 FILEID_NILFS_WITHOUT_PARENT = 0x61,
81
82 /*
83 * 64 bit checkpoint number, 64 bit inode number,
84 * 32 bit generation number, 32 bit parent generation.
85 * 64 bit parent inode number.
86 */
87 FILEID_NILFS_WITH_PARENT = 0x62,
88
89 /*
90 * 32 bit generation number, 40 bit i_pos.
91 */
92 FILEID_FAT_WITHOUT_PARENT = 0x71,
93
94 /*
95 * 32 bit generation number, 40 bit i_pos,
96 * 32 bit parent generation number, 40 bit parent i_pos
97 */
98 FILEID_FAT_WITH_PARENT = 0x72,
99
100 /*
101 * 128 bit child FID (struct lu_fid)
102 * 128 bit parent FID (struct lu_fid)
103 */
104 FILEID_LUSTRE = 0x97,
105
106 /*
107 * Filesystems must not use 0xff file ID.
108 */
109 FILEID_INVALID = 0xff,
110};
111
112struct fid {
113 union {
114 struct {
115 u32 ino;
116 u32 gen;
117 u32 parent_ino;
118 u32 parent_gen;
119 } i32;
120 struct {
121 u32 block;
122 u16 partref;
123 u16 parent_partref;
124 u32 generation;
125 u32 parent_block;
126 u32 parent_generation;
127 } udf;
128 __u32 raw[0];
129 };
130};
131
132/**
133 * struct export_operations - for nfsd to communicate with file systems
134 * @encode_fh: encode a file handle fragment from a dentry
135 * @fh_to_dentry: find the implied object and get a dentry for it
136 * @fh_to_parent: find the implied object's parent and get a dentry for it
137 * @get_name: find the name for a given inode in a given directory
138 * @get_parent: find the parent of a given directory
139 * @commit_metadata: commit metadata changes to stable storage
140 *
141 * See Documentation/filesystems/nfs/Exporting for details on how to use
142 * this interface correctly.
143 *
144 * encode_fh:
145 * @encode_fh should store in the file handle fragment @fh (using at most
146 * @max_len bytes) information that can be used by @decode_fh to recover the
147 * file referred to by the &struct dentry @de. If the @connectable flag is
148 * set, the encode_fh() should store sufficient information so that a good
149 * attempt can be made to find not only the file but also it's place in the
150 * filesystem. This typically means storing a reference to de->d_parent in
151 * the filehandle fragment. encode_fh() should return the fileid_type on
152 * success and on error returns 255 (if the space needed to encode fh is
153 * greater than @max_len*4 bytes). On error @max_len contains the minimum
154 * size(in 4 byte unit) needed to encode the file handle.
155 *
156 * fh_to_dentry:
157 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
158 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
159 * to the same file that the file handle fragment refers to. If it cannot,
160 * it should return a %NULL pointer if the file was found but no acceptable
161 * &dentries were available, or an %ERR_PTR error code indicating why it
162 * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be
163 * returned including, if necessary, a new dentry created with d_alloc_root.
164 * The caller can then find any other extant dentries by following the
165 * d_alias links.
166 *
167 * fh_to_parent:
168 * Same as @fh_to_dentry, except that it returns a pointer to the parent
169 * dentry if it was encoded into the filehandle fragment by @encode_fh.
170 *
171 * get_name:
172 * @get_name should find a name for the given @child in the given @parent
173 * directory. The name should be stored in the @name (with the
174 * understanding that it is already pointing to a a %NAME_MAX+1 sized
175 * buffer. get_name() should return %0 on success, a negative error code
176 * or error. @get_name will be called without @parent->i_mutex held.
177 *
178 * get_parent:
179 * @get_parent should find the parent directory for the given @child which
180 * is also a directory. In the event that it cannot be found, or storage
181 * space cannot be allocated, a %ERR_PTR should be returned.
182 *
183 * commit_metadata:
184 * @commit_metadata should commit metadata changes to stable storage.
185 *
186 * Locking rules:
187 * get_parent is called with child->d_inode->i_mutex down
188 * get_name is not (which is possibly inconsistent)
189 */
190
191struct export_operations {
192 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
193 struct inode *parent);
194 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
195 int fh_len, int fh_type);
196 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
197 int fh_len, int fh_type);
198 int (*get_name)(struct dentry *parent, char *name,
199 struct dentry *child);
200 struct dentry * (*get_parent)(struct dentry *child);
201 int (*commit_metadata)(struct inode *inode);
202
203 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
204 int (*map_blocks)(struct inode *inode, loff_t offset,
205 u64 len, struct iomap *iomap,
206 bool write, u32 *device_generation);
207 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
208 int nr_iomaps, struct iattr *iattr);
209};
210
211extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
212 int *max_len, struct inode *parent);
213extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
214 int *max_len, int connectable);
215extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
216 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
217 void *context);
218
219/*
220 * Generic helpers for filesystems.
221 */
222extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
223 struct fid *fid, int fh_len, int fh_type,
224 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
225extern struct dentry *generic_fh_to_parent(struct super_block *sb,
226 struct fid *fid, int fh_len, int fh_type,
227 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
228
229#endif /* LINUX_EXPORTFS_H */