1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef LINUX_EXPORTFS_H
3 #define LINUX_EXPORTFS_H 1
4
5 #include <linux/types.h>
6
7 struct dentry;
8 struct iattr;
9 struct inode;
10 struct iomap;
11 struct super_block;
12 struct vfsmount;
13
14 /* limit the handle size to NFSv4 handle size now */
15 #define MAX_HANDLE_SZ 128
16
17 /*
18 * The fileid_type identifies how the file within the filesystem is encoded.
19 * In theory this is freely set and parsed by the filesystem, but we try to
20 * stick to conventions so we can share some generic code and don't confuse
21 * sniffers like ethereal/wireshark.
22 *
23 * The filesystem must not use the value '0' or '0xff'.
24 */
25 enum fid_type {
26 /*
27 * The root, or export point, of the filesystem.
28 * (Never actually passed down to the filesystem.
29 */
30 FILEID_ROOT = 0,
31
32 /*
33 * 32bit inode number, 32 bit generation number.
34 */
35 FILEID_INO32_GEN = 1,
36
37 /*
38 * 32bit inode number, 32 bit generation number,
39 * 32 bit parent directory inode number.
40 */
41 FILEID_INO32_GEN_PARENT = 2,
42
43 /*
44 * 64 bit object ID, 64 bit root object ID,
45 * 32 bit generation number.
46 */
47 FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
48
49 /*
50 * 64 bit object ID, 64 bit root object ID,
51 * 32 bit generation number,
52 * 64 bit parent object ID, 32 bit parent generation.
53 */
54 FILEID_BTRFS_WITH_PARENT = 0x4e,
55
56 /*
57 * 64 bit object ID, 64 bit root object ID,
58 * 32 bit generation number,
59 * 64 bit parent object ID, 32 bit parent generation,
60 * 64 bit parent root object ID.
61 */
62 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
63
64 /*
65 * 32 bit block number, 16 bit partition reference,
66 * 16 bit unused, 32 bit generation number.
67 */
68 FILEID_UDF_WITHOUT_PARENT = 0x51,
69
70 /*
71 * 32 bit block number, 16 bit partition reference,
72 * 16 bit unused, 32 bit generation number,
73 * 32 bit parent block number, 32 bit parent generation number
74 */
75 FILEID_UDF_WITH_PARENT = 0x52,
76
77 /*
78 * 64 bit checkpoint number, 64 bit inode number,
79 * 32 bit generation number.
80 */
81 FILEID_NILFS_WITHOUT_PARENT = 0x61,
82
83 /*
84 * 64 bit checkpoint number, 64 bit inode number,
85 * 32 bit generation number, 32 bit parent generation.
86 * 64 bit parent inode number.
87 */
88 FILEID_NILFS_WITH_PARENT = 0x62,
89
90 /*
91 * 32 bit generation number, 40 bit i_pos.
92 */
93 FILEID_FAT_WITHOUT_PARENT = 0x71,
94
95 /*
96 * 32 bit generation number, 40 bit i_pos,
97 * 32 bit parent generation number, 40 bit parent i_pos
98 */
99 FILEID_FAT_WITH_PARENT = 0x72,
100
101 /*
102 * 128 bit child FID (struct lu_fid)
103 * 128 bit parent FID (struct lu_fid)
104 */
105 FILEID_LUSTRE = 0x97,
106
107 /*
108 * Filesystems must not use 0xff file ID.
109 */
110 FILEID_INVALID = 0xff,
111 };
112
113 struct fid {
114 union {
115 struct {
116 u32 ino;
117 u32 gen;
118 u32 parent_ino;
119 u32 parent_gen;
120 } i32;
121 struct {
122 u32 block;
123 u16 partref;
124 u16 parent_partref;
125 u32 generation;
126 u32 parent_block;
127 u32 parent_generation;
128 } udf;
129 __u32 raw[0];
130 };
131 };
132
133 /**
134 * struct export_operations - for nfsd to communicate with file systems
135 * @encode_fh: encode a file handle fragment from a dentry
136 * @fh_to_dentry: find the implied object and get a dentry for it
137 * @fh_to_parent: find the implied object's parent and get a dentry for it
138 * @get_name: find the name for a given inode in a given directory
139 * @get_parent: find the parent of a given directory
140 * @commit_metadata: commit metadata changes to stable storage
141 *
142 * See Documentation/filesystems/nfs/exporting.rst for details on how to use
143 * this interface correctly.
144 *
145 * encode_fh:
146 * @encode_fh should store in the file handle fragment @fh (using at most
147 * @max_len bytes) information that can be used by @decode_fh to recover the
148 * file referred to by the &struct dentry @de. If the @connectable flag is
149 * set, the encode_fh() should store sufficient information so that a good
150 * attempt can be made to find not only the file but also it's place in the
151 * filesystem. This typically means storing a reference to de->d_parent in
152 * the filehandle fragment. encode_fh() should return the fileid_type on
153 * success and on error returns 255 (if the space needed to encode fh is
154 * greater than @max_len*4 bytes). On error @max_len contains the minimum
155 * size(in 4 byte unit) needed to encode the file handle.
156 *
157 * fh_to_dentry:
158 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
159 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
160 * to the same file that the file handle fragment refers to. If it cannot,
161 * it should return a %NULL pointer if the file cannot be found, or an
162 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
163 * Any other error code is treated like %NULL, and will cause an %ESTALE error
164 * for callers of exportfs_decode_fh().
165 * Any suitable dentry can be returned including, if necessary, a new dentry
166 * created with d_alloc_root. The caller can then find any other extant
167 * dentries by following the d_alias links.
168 *
169 * fh_to_parent:
170 * Same as @fh_to_dentry, except that it returns a pointer to the parent
171 * dentry if it was encoded into the filehandle fragment by @encode_fh.
172 *
173 * get_name:
174 * @get_name should find a name for the given @child in the given @parent
175 * directory. The name should be stored in the @name (with the
176 * understanding that it is already pointing to a a %NAME_MAX+1 sized
177 * buffer. get_name() should return %0 on success, a negative error code
178 * or error. @get_name will be called without @parent->i_mutex held.
179 *
180 * get_parent:
181 * @get_parent should find the parent directory for the given @child which
182 * is also a directory. In the event that it cannot be found, or storage
183 * space cannot be allocated, a %ERR_PTR should be returned.
184 *
185 * commit_metadata:
186 * @commit_metadata should commit metadata changes to stable storage.
187 *
188 * Locking rules:
189 * get_parent is called with child->d_inode->i_mutex down
190 * get_name is not (which is possibly inconsistent)
191 */
192
193 struct export_operations {
194 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
195 struct inode *parent);
196 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
197 int fh_len, int fh_type);
198 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
199 int fh_len, int fh_type);
200 int (*get_name)(struct dentry *parent, char *name,
201 struct dentry *child);
202 struct dentry * (*get_parent)(struct dentry *child);
203 int (*commit_metadata)(struct inode *inode);
204
205 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
206 int (*map_blocks)(struct inode *inode, loff_t offset,
207 u64 len, struct iomap *iomap,
208 bool write, u32 *device_generation);
209 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
210 int nr_iomaps, struct iattr *iattr);
211 };
212
213 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
214 int *max_len, struct inode *parent);
215 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
216 int *max_len, int connectable);
217 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
218 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
219 void *context);
220
221 /*
222 * Generic helpers for filesystems.
223 */
224 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
225 struct fid *fid, int fh_len, int fh_type,
226 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
227 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
228 struct fid *fid, int fh_len, int fh_type,
229 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
230
231 #endif /* LINUX_EXPORTFS_H */