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 #include <linux/path.h> 7 8 struct dentry; 9 struct iattr; 10 struct inode; 11 struct iomap; 12 struct super_block; 13 struct vfsmount; 14 15 /* limit the handle size to NFSv4 handle size now */ 16 #define MAX_HANDLE_SZ 128 17 18 /* 19 * The fileid_type identifies how the file within the filesystem is encoded. 20 * In theory this is freely set and parsed by the filesystem, but we try to 21 * stick to conventions so we can share some generic code and don't confuse 22 * sniffers like ethereal/wireshark. 23 * 24 * The filesystem must not use the value '0' or '0xff'. 25 */ 26 enum fid_type { 27 /* 28 * The root, or export point, of the filesystem. 29 * (Never actually passed down to the filesystem. 30 */ 31 FILEID_ROOT = 0, 32 33 /* 34 * 32bit inode number, 32 bit generation number. 35 */ 36 FILEID_INO32_GEN = 1, 37 38 /* 39 * 32bit inode number, 32 bit generation number, 40 * 32 bit parent directory inode number. 41 */ 42 FILEID_INO32_GEN_PARENT = 2, 43 44 /* 45 * 64 bit object ID, 64 bit root object ID, 46 * 32 bit generation number. 47 */ 48 FILEID_BTRFS_WITHOUT_PARENT = 0x4d, 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 */ 55 FILEID_BTRFS_WITH_PARENT = 0x4e, 56 57 /* 58 * 64 bit object ID, 64 bit root object ID, 59 * 32 bit generation number, 60 * 64 bit parent object ID, 32 bit parent generation, 61 * 64 bit parent root object ID. 62 */ 63 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f, 64 65 /* 66 * 32 bit block number, 16 bit partition reference, 67 * 16 bit unused, 32 bit generation number. 68 */ 69 FILEID_UDF_WITHOUT_PARENT = 0x51, 70 71 /* 72 * 32 bit block number, 16 bit partition reference, 73 * 16 bit unused, 32 bit generation number, 74 * 32 bit parent block number, 32 bit parent generation number 75 */ 76 FILEID_UDF_WITH_PARENT = 0x52, 77 78 /* 79 * 64 bit checkpoint number, 64 bit inode number, 80 * 32 bit generation number. 81 */ 82 FILEID_NILFS_WITHOUT_PARENT = 0x61, 83 84 /* 85 * 64 bit checkpoint number, 64 bit inode number, 86 * 32 bit generation number, 32 bit parent generation. 87 * 64 bit parent inode number. 88 */ 89 FILEID_NILFS_WITH_PARENT = 0x62, 90 91 /* 92 * 32 bit generation number, 40 bit i_pos. 93 */ 94 FILEID_FAT_WITHOUT_PARENT = 0x71, 95 96 /* 97 * 32 bit generation number, 40 bit i_pos, 98 * 32 bit parent generation number, 40 bit parent i_pos 99 */ 100 FILEID_FAT_WITH_PARENT = 0x72, 101 102 /* 103 * 64 bit inode number, 32 bit generation number. 104 */ 105 FILEID_INO64_GEN = 0x81, 106 107 /* 108 * 64 bit inode number, 32 bit generation number, 109 * 64 bit parent inode number, 32 bit parent generation. 110 */ 111 FILEID_INO64_GEN_PARENT = 0x82, 112 113 /* 114 * 128 bit child FID (struct lu_fid) 115 * 128 bit parent FID (struct lu_fid) 116 */ 117 FILEID_LUSTRE = 0x97, 118 119 /* 120 * 64 bit inode number, 32 bit subvolume, 32 bit generation number: 121 */ 122 FILEID_BCACHEFS_WITHOUT_PARENT = 0xb1, 123 FILEID_BCACHEFS_WITH_PARENT = 0xb2, 124 125 /* 126 * 127 * 64 bit namespace identifier, 32 bit namespace type, 32 bit inode number. 128 */ 129 FILEID_NSFS = 0xf1, 130 131 /* 132 * 64 bit unique kernfs id 133 */ 134 FILEID_KERNFS = 0xfe, 135 136 /* 137 * Filesystems must not use 0xff file ID. 138 */ 139 FILEID_INVALID = 0xff, 140 }; 141 142 struct fid { 143 union { 144 struct { 145 u32 ino; 146 u32 gen; 147 u32 parent_ino; 148 u32 parent_gen; 149 } i32; 150 struct { 151 u64 ino; 152 u32 gen; 153 } __packed i64; 154 struct { 155 u32 block; 156 u16 partref; 157 u16 parent_partref; 158 u32 generation; 159 u32 parent_block; 160 u32 parent_generation; 161 } udf; 162 DECLARE_FLEX_ARRAY(__u32, raw); 163 }; 164 }; 165 166 enum handle_to_path_flags { 167 HANDLE_CHECK_PERMS = (1 << 0), 168 HANDLE_CHECK_SUBTREE = (1 << 1), 169 }; 170 171 struct handle_to_path_ctx { 172 struct path root; 173 enum handle_to_path_flags flags; 174 unsigned int fh_flags; 175 }; 176 177 #define EXPORT_FH_CONNECTABLE 0x1 /* Encode file handle with parent */ 178 #define EXPORT_FH_FID 0x2 /* File handle may be non-decodeable */ 179 #define EXPORT_FH_DIR_ONLY 0x4 /* Only decode file handle for a directory */ 180 181 /* 182 * Filesystems use only lower 8 bits of file_handle type for fid_type. 183 * name_to_handle_at() uses upper 16 bits of type as user flags to be 184 * interpreted by open_by_handle_at(). 185 */ 186 #define FILEID_USER_FLAGS_MASK 0xffff0000 187 #define FILEID_USER_FLAGS(type) ((type) & FILEID_USER_FLAGS_MASK) 188 189 /* Flags supported in encoded handle_type that is exported to user */ 190 #define FILEID_IS_CONNECTABLE 0x10000 191 #define FILEID_IS_DIR 0x20000 192 #define FILEID_VALID_USER_FLAGS (FILEID_IS_CONNECTABLE | FILEID_IS_DIR) 193 194 /** 195 * struct export_operations - for nfsd to communicate with file systems 196 * @encode_fh: encode a file handle fragment from a dentry 197 * @fh_to_dentry: find the implied object and get a dentry for it 198 * @fh_to_parent: find the implied object's parent and get a dentry for it 199 * @get_name: find the name for a given inode in a given directory 200 * @get_parent: find the parent of a given directory 201 * @commit_metadata: commit metadata changes to stable storage 202 * 203 * See Documentation/filesystems/nfs/exporting.rst for details on how to use 204 * this interface correctly and the definition of the flags. 205 * 206 * @encode_fh: 207 * @encode_fh should store in the file handle fragment @fh (using at most 208 * @max_len bytes) information that can be used by @decode_fh to recover the 209 * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit 210 * set, the encode_fh() should store sufficient information so that a good 211 * attempt can be made to find not only the file but also it's place in the 212 * filesystem. This typically means storing a reference to de->d_parent in 213 * the filehandle fragment. encode_fh() should return the fileid_type on 214 * success and on error returns 255 (if the space needed to encode fh is 215 * greater than @max_len*4 bytes). On error @max_len contains the minimum 216 * size(in 4 byte unit) needed to encode the file handle. 217 * 218 * @fh_to_dentry: 219 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 220 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 221 * to the same file that the file handle fragment refers to. If it cannot, 222 * it should return a %NULL pointer if the file cannot be found, or an 223 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred. 224 * Any other error code is treated like %NULL, and will cause an %ESTALE error 225 * for callers of exportfs_decode_fh(). 226 * Any suitable dentry can be returned including, if necessary, a new dentry 227 * created with d_alloc_root. The caller can then find any other extant 228 * dentries by following the d_alias links. 229 * 230 * @fh_to_parent: 231 * Same as @fh_to_dentry, except that it returns a pointer to the parent 232 * dentry if it was encoded into the filehandle fragment by @encode_fh. 233 * 234 * @get_name: 235 * @get_name should find a name for the given @child in the given @parent 236 * directory. The name should be stored in the @name (with the 237 * understanding that it is already pointing to a %NAME_MAX + 1 sized 238 * buffer. get_name() should return %0 on success, a negative error code 239 * or error. @get_name will be called without @parent->i_rwsem held. 240 * 241 * @get_parent: 242 * @get_parent should find the parent directory for the given @child which 243 * is also a directory. In the event that it cannot be found, or storage 244 * space cannot be allocated, a %ERR_PTR should be returned. 245 * 246 * @permission: 247 * Allow filesystems to specify a custom permission function. 248 * 249 * @open: 250 * Allow filesystems to specify a custom open function. 251 * 252 * @commit_metadata: 253 * @commit_metadata should commit metadata changes to stable storage. 254 * 255 * @get_uuid: 256 * Get a filesystem unique signature exposed to clients. 257 * 258 * @map_blocks: 259 * Map and, if necessary, allocate blocks for a layout. 260 * 261 * @commit_blocks: 262 * Commit blocks in a layout once the client is done with them. 263 * 264 * @flags: 265 * Allows the filesystem to communicate to nfsd that it may want to do things 266 * differently when dealing with it. 267 * 268 * Locking rules: 269 * get_parent is called with child->d_inode->i_rwsem down 270 * get_name is not (which is possibly inconsistent) 271 */ 272 273 struct export_operations { 274 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, 275 struct inode *parent); 276 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 277 int fh_len, int fh_type); 278 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 279 int fh_len, int fh_type); 280 int (*get_name)(struct dentry *parent, char *name, 281 struct dentry *child); 282 struct dentry * (*get_parent)(struct dentry *child); 283 int (*commit_metadata)(struct inode *inode); 284 285 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset); 286 int (*map_blocks)(struct inode *inode, loff_t offset, 287 u64 len, struct iomap *iomap, 288 bool write, u32 *device_generation); 289 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, 290 int nr_iomaps, struct iattr *iattr); 291 int (*permission)(struct handle_to_path_ctx *ctx, unsigned int oflags); 292 struct file * (*open)(const struct path *path, unsigned int oflags); 293 #define EXPORT_OP_NOWCC (0x1) /* don't collect v3 wcc data */ 294 #define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */ 295 #define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */ 296 #define EXPORT_OP_REMOTE_FS (0x8) /* Filesystem is remote */ 297 #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply 298 atomic attribute updates 299 */ 300 #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */ 301 #define EXPORT_OP_NOLOCKS (0x40) /* no file locking support */ 302 unsigned long flags; 303 }; 304 305 /** 306 * exportfs_cannot_lock() - check if export implements file locking 307 * @export_ops: the nfs export operations to check 308 * 309 * Returns true if the export does not support file locking. 310 */ 311 static inline bool 312 exportfs_cannot_lock(const struct export_operations *export_ops) 313 { 314 return export_ops->flags & EXPORT_OP_NOLOCKS; 315 } 316 317 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, 318 int *max_len, struct inode *parent, 319 int flags); 320 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 321 int *max_len, int flags); 322 323 static inline bool exportfs_can_encode_fid(const struct export_operations *nop) 324 { 325 return !nop || nop->encode_fh; 326 } 327 328 static inline bool exportfs_can_decode_fh(const struct export_operations *nop) 329 { 330 return nop && nop->fh_to_dentry; 331 } 332 333 static inline bool exportfs_can_encode_fh(const struct export_operations *nop, 334 int fh_flags) 335 { 336 /* 337 * If a non-decodeable file handle was requested, we only need to make 338 * sure that filesystem did not opt-out of encoding fid. 339 */ 340 if (fh_flags & EXPORT_FH_FID) 341 return exportfs_can_encode_fid(nop); 342 343 /* Normal file handles cannot be created without export ops */ 344 if (!nop) 345 return false; 346 347 /* 348 * If a connectable file handle was requested, we need to make sure that 349 * filesystem can also decode connected file handles. 350 */ 351 if ((fh_flags & EXPORT_FH_CONNECTABLE) && !nop->fh_to_parent) 352 return false; 353 354 /* 355 * If a decodeable file handle was requested, we need to make sure that 356 * filesystem can also decode file handles. 357 */ 358 return exportfs_can_decode_fh(nop); 359 } 360 361 static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid, 362 int *max_len) 363 { 364 return exportfs_encode_inode_fh(inode, fid, max_len, NULL, 365 EXPORT_FH_FID); 366 } 367 368 extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt, 369 struct fid *fid, int fh_len, 370 int fileid_type, 371 unsigned int flags, 372 int (*acceptable)(void *, struct dentry *), 373 void *context); 374 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 375 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 376 void *context); 377 378 /* 379 * Generic helpers for filesystems. 380 */ 381 int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, 382 struct inode *parent); 383 struct dentry *generic_fh_to_dentry(struct super_block *sb, 384 struct fid *fid, int fh_len, int fh_type, 385 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 386 struct dentry *generic_fh_to_parent(struct super_block *sb, 387 struct fid *fid, int fh_len, int fh_type, 388 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 389 390 #endif /* LINUX_EXPORTFS_H */ 391