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 #define EXPORT_FH_DIR_ONLY 0x4 /* Only decode file handle for a directory */ 162 163 /* 164 * Filesystems use only lower 8 bits of file_handle type for fid_type. 165 * name_to_handle_at() uses upper 16 bits of type as user flags to be 166 * interpreted by open_by_handle_at(). 167 */ 168 #define FILEID_USER_FLAGS_MASK 0xffff0000 169 #define FILEID_USER_FLAGS(type) ((type) & FILEID_USER_FLAGS_MASK) 170 171 /* Flags supported in encoded handle_type that is exported to user */ 172 #define FILEID_VALID_USER_FLAGS (0) 173 174 /** 175 * struct export_operations - for nfsd to communicate with file systems 176 * @encode_fh: encode a file handle fragment from a dentry 177 * @fh_to_dentry: find the implied object and get a dentry for it 178 * @fh_to_parent: find the implied object's parent and get a dentry for it 179 * @get_name: find the name for a given inode in a given directory 180 * @get_parent: find the parent of a given directory 181 * @commit_metadata: commit metadata changes to stable storage 182 * 183 * See Documentation/filesystems/nfs/exporting.rst for details on how to use 184 * this interface correctly. 185 * 186 * encode_fh: 187 * @encode_fh should store in the file handle fragment @fh (using at most 188 * @max_len bytes) information that can be used by @decode_fh to recover the 189 * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit 190 * set, the encode_fh() should store sufficient information so that a good 191 * attempt can be made to find not only the file but also it's place in the 192 * filesystem. This typically means storing a reference to de->d_parent in 193 * the filehandle fragment. encode_fh() should return the fileid_type on 194 * success and on error returns 255 (if the space needed to encode fh is 195 * greater than @max_len*4 bytes). On error @max_len contains the minimum 196 * size(in 4 byte unit) needed to encode the file handle. 197 * 198 * fh_to_dentry: 199 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 200 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 201 * to the same file that the file handle fragment refers to. If it cannot, 202 * it should return a %NULL pointer if the file cannot be found, or an 203 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred. 204 * Any other error code is treated like %NULL, and will cause an %ESTALE error 205 * for callers of exportfs_decode_fh(). 206 * Any suitable dentry can be returned including, if necessary, a new dentry 207 * created with d_alloc_root. The caller can then find any other extant 208 * dentries by following the d_alias links. 209 * 210 * fh_to_parent: 211 * Same as @fh_to_dentry, except that it returns a pointer to the parent 212 * dentry if it was encoded into the filehandle fragment by @encode_fh. 213 * 214 * get_name: 215 * @get_name should find a name for the given @child in the given @parent 216 * directory. The name should be stored in the @name (with the 217 * understanding that it is already pointing to a %NAME_MAX+1 sized 218 * buffer. get_name() should return %0 on success, a negative error code 219 * or error. @get_name will be called without @parent->i_mutex held. 220 * 221 * get_parent: 222 * @get_parent should find the parent directory for the given @child which 223 * is also a directory. In the event that it cannot be found, or storage 224 * space cannot be allocated, a %ERR_PTR should be returned. 225 * 226 * commit_metadata: 227 * @commit_metadata should commit metadata changes to stable storage. 228 * 229 * Locking rules: 230 * get_parent is called with child->d_inode->i_mutex down 231 * get_name is not (which is possibly inconsistent) 232 */ 233 234 struct export_operations { 235 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, 236 struct inode *parent); 237 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 238 int fh_len, int fh_type); 239 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 240 int fh_len, int fh_type); 241 int (*get_name)(struct dentry *parent, char *name, 242 struct dentry *child); 243 struct dentry * (*get_parent)(struct dentry *child); 244 int (*commit_metadata)(struct inode *inode); 245 246 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset); 247 int (*map_blocks)(struct inode *inode, loff_t offset, 248 u64 len, struct iomap *iomap, 249 bool write, u32 *device_generation); 250 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, 251 int nr_iomaps, struct iattr *iattr); 252 #define EXPORT_OP_NOWCC (0x1) /* don't collect v3 wcc data */ 253 #define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */ 254 #define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */ 255 #define EXPORT_OP_REMOTE_FS (0x8) /* Filesystem is remote */ 256 #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply 257 atomic attribute updates 258 */ 259 #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */ 260 #define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */ 261 unsigned long flags; 262 }; 263 264 /** 265 * exportfs_lock_op_is_async() - export op supports async lock operation 266 * @export_ops: the nfs export operations to check 267 * 268 * Returns true if the nfs export_operations structure has 269 * EXPORT_OP_ASYNC_LOCK in their flags set 270 */ 271 static inline bool 272 exportfs_lock_op_is_async(const struct export_operations *export_ops) 273 { 274 return export_ops->flags & EXPORT_OP_ASYNC_LOCK; 275 } 276 277 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, 278 int *max_len, struct inode *parent, 279 int flags); 280 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 281 int *max_len, int flags); 282 283 static inline bool exportfs_can_encode_fid(const struct export_operations *nop) 284 { 285 return !nop || nop->encode_fh; 286 } 287 288 static inline bool exportfs_can_decode_fh(const struct export_operations *nop) 289 { 290 return nop && nop->fh_to_dentry; 291 } 292 293 static inline bool exportfs_can_encode_fh(const struct export_operations *nop, 294 int fh_flags) 295 { 296 /* 297 * If a non-decodeable file handle was requested, we only need to make 298 * sure that filesystem did not opt-out of encoding fid. 299 */ 300 if (fh_flags & EXPORT_FH_FID) 301 return exportfs_can_encode_fid(nop); 302 303 /* 304 * If a decodeable file handle was requested, we need to make sure that 305 * filesystem can also decode file handles. 306 */ 307 return exportfs_can_decode_fh(nop); 308 } 309 310 static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid, 311 int *max_len) 312 { 313 return exportfs_encode_inode_fh(inode, fid, max_len, NULL, 314 EXPORT_FH_FID); 315 } 316 317 extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt, 318 struct fid *fid, int fh_len, 319 int fileid_type, 320 unsigned int flags, 321 int (*acceptable)(void *, struct dentry *), 322 void *context); 323 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 324 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 325 void *context); 326 327 /* 328 * Generic helpers for filesystems. 329 */ 330 int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, 331 struct inode *parent); 332 struct dentry *generic_fh_to_dentry(struct super_block *sb, 333 struct fid *fid, int fh_len, int fh_type, 334 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 335 struct dentry *generic_fh_to_parent(struct super_block *sb, 336 struct fid *fid, int fh_len, int fh_type, 337 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 338 339 #endif /* LINUX_EXPORTFS_H */ 340