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 * 64 bit inode number, 32 bit generation number.
103 */
104 FILEID_INO64_GEN = 0x81,
105
106 /*
107 * 64 bit inode number, 32 bit generation number,
108 * 64 bit parent inode number, 32 bit parent generation.
109 */
110 FILEID_INO64_GEN_PARENT = 0x82,
111
112 /*
113 * 128 bit child FID (struct lu_fid)
114 * 128 bit parent FID (struct lu_fid)
115 */
116 FILEID_LUSTRE = 0x97,
117
118 /*
119 * 64 bit inode number, 32 bit subvolume, 32 bit generation number:
120 */
121 FILEID_BCACHEFS_WITHOUT_PARENT = 0xb1,
122 FILEID_BCACHEFS_WITH_PARENT = 0xb2,
123
124 /*
125 * 64 bit unique kernfs id
126 */
127 FILEID_KERNFS = 0xfe,
128
129 /*
130 * Filesystems must not use 0xff file ID.
131 */
132 FILEID_INVALID = 0xff,
133 };
134
135 struct fid {
136 union {
137 struct {
138 u32 ino;
139 u32 gen;
140 u32 parent_ino;
141 u32 parent_gen;
142 } i32;
143 struct {
144 u64 ino;
145 u32 gen;
146 } __packed i64;
147 struct {
148 u32 block;
149 u16 partref;
150 u16 parent_partref;
151 u32 generation;
152 u32 parent_block;
153 u32 parent_generation;
154 } udf;
155 DECLARE_FLEX_ARRAY(__u32, raw);
156 };
157 };
158
159 #define EXPORT_FH_CONNECTABLE 0x1 /* Encode file handle with parent */
160 #define EXPORT_FH_FID 0x2 /* File handle may be non-decodeable */
161
162 /**
163 * struct export_operations - for nfsd to communicate with file systems
164 * @encode_fh: encode a file handle fragment from a dentry
165 * @fh_to_dentry: find the implied object and get a dentry for it
166 * @fh_to_parent: find the implied object's parent and get a dentry for it
167 * @get_name: find the name for a given inode in a given directory
168 * @get_parent: find the parent of a given directory
169 * @commit_metadata: commit metadata changes to stable storage
170 *
171 * See Documentation/filesystems/nfs/exporting.rst for details on how to use
172 * this interface correctly.
173 *
174 * encode_fh:
175 * @encode_fh should store in the file handle fragment @fh (using at most
176 * @max_len bytes) information that can be used by @decode_fh to recover the
177 * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit
178 * set, the encode_fh() should store sufficient information so that a good
179 * attempt can be made to find not only the file but also it's place in the
180 * filesystem. This typically means storing a reference to de->d_parent in
181 * the filehandle fragment. encode_fh() should return the fileid_type on
182 * success and on error returns 255 (if the space needed to encode fh is
183 * greater than @max_len*4 bytes). On error @max_len contains the minimum
184 * size(in 4 byte unit) needed to encode the file handle.
185 *
186 * fh_to_dentry:
187 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
188 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
189 * to the same file that the file handle fragment refers to. If it cannot,
190 * it should return a %NULL pointer if the file cannot be found, or an
191 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
192 * Any other error code is treated like %NULL, and will cause an %ESTALE error
193 * for callers of exportfs_decode_fh().
194 * Any suitable dentry can be returned including, if necessary, a new dentry
195 * created with d_alloc_root. The caller can then find any other extant
196 * dentries by following the d_alias links.
197 *
198 * fh_to_parent:
199 * Same as @fh_to_dentry, except that it returns a pointer to the parent
200 * dentry if it was encoded into the filehandle fragment by @encode_fh.
201 *
202 * get_name:
203 * @get_name should find a name for the given @child in the given @parent
204 * directory. The name should be stored in the @name (with the
205 * understanding that it is already pointing to a %NAME_MAX+1 sized
206 * buffer. get_name() should return %0 on success, a negative error code
207 * or error. @get_name will be called without @parent->i_mutex held.
208 *
209 * get_parent:
210 * @get_parent should find the parent directory for the given @child which
211 * is also a directory. In the event that it cannot be found, or storage
212 * space cannot be allocated, a %ERR_PTR should be returned.
213 *
214 * commit_metadata:
215 * @commit_metadata should commit metadata changes to stable storage.
216 *
217 * Locking rules:
218 * get_parent is called with child->d_inode->i_mutex down
219 * get_name is not (which is possibly inconsistent)
220 */
221
222 struct export_operations {
223 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
224 struct inode *parent);
225 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
226 int fh_len, int fh_type);
227 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
228 int fh_len, int fh_type);
229 int (*get_name)(struct dentry *parent, char *name,
230 struct dentry *child);
231 struct dentry * (*get_parent)(struct dentry *child);
232 int (*commit_metadata)(struct inode *inode);
233
234 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
235 int (*map_blocks)(struct inode *inode, loff_t offset,
236 u64 len, struct iomap *iomap,
237 bool write, u32 *device_generation);
238 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
239 int nr_iomaps, struct iattr *iattr);
240 #define EXPORT_OP_NOWCC (0x1) /* don't collect v3 wcc data */
241 #define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */
242 #define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */
243 #define EXPORT_OP_REMOTE_FS (0x8) /* Filesystem is remote */
244 #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply
245 atomic attribute updates
246 */
247 #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */
248 #define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */
249 unsigned long flags;
250 };
251
252 /**
253 * exportfs_lock_op_is_async() - export op supports async lock operation
254 * @export_ops: the nfs export operations to check
255 *
256 * Returns true if the nfs export_operations structure has
257 * EXPORT_OP_ASYNC_LOCK in their flags set
258 */
259 static inline bool
exportfs_lock_op_is_async(const struct export_operations * export_ops)260 exportfs_lock_op_is_async(const struct export_operations *export_ops)
261 {
262 return export_ops->flags & EXPORT_OP_ASYNC_LOCK;
263 }
264
265 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
266 int *max_len, struct inode *parent,
267 int flags);
268 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
269 int *max_len, int flags);
270
exportfs_can_encode_fid(const struct export_operations * nop)271 static inline bool exportfs_can_encode_fid(const struct export_operations *nop)
272 {
273 return !nop || nop->encode_fh;
274 }
275
exportfs_can_decode_fh(const struct export_operations * nop)276 static inline bool exportfs_can_decode_fh(const struct export_operations *nop)
277 {
278 return nop && nop->fh_to_dentry;
279 }
280
exportfs_can_encode_fh(const struct export_operations * nop,int fh_flags)281 static inline bool exportfs_can_encode_fh(const struct export_operations *nop,
282 int fh_flags)
283 {
284 /*
285 * If a non-decodeable file handle was requested, we only need to make
286 * sure that filesystem did not opt-out of encoding fid.
287 */
288 if (fh_flags & EXPORT_FH_FID)
289 return exportfs_can_encode_fid(nop);
290
291 /*
292 * If a decodeable file handle was requested, we need to make sure that
293 * filesystem can also decode file handles.
294 */
295 return exportfs_can_decode_fh(nop);
296 }
297
exportfs_encode_fid(struct inode * inode,struct fid * fid,int * max_len)298 static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid,
299 int *max_len)
300 {
301 return exportfs_encode_inode_fh(inode, fid, max_len, NULL,
302 EXPORT_FH_FID);
303 }
304
305 extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt,
306 struct fid *fid, int fh_len,
307 int fileid_type,
308 int (*acceptable)(void *, struct dentry *),
309 void *context);
310 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
311 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
312 void *context);
313
314 /*
315 * Generic helpers for filesystems.
316 */
317 int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len,
318 struct inode *parent);
319 struct dentry *generic_fh_to_dentry(struct super_block *sb,
320 struct fid *fid, int fh_len, int fh_type,
321 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
322 struct dentry *generic_fh_to_parent(struct super_block *sb,
323 struct fid *fid, int fh_len, int fh_type,
324 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
325
326 #endif /* LINUX_EXPORTFS_H */
327