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 struct path; 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 * 64 bit unique kernfs id 127 */ 128 FILEID_KERNFS = 0xfe, 129 130 /* 131 * Filesystems must not use 0xff file ID. 132 */ 133 FILEID_INVALID = 0xff, 134 }; 135 136 struct fid { 137 union { 138 struct { 139 u32 ino; 140 u32 gen; 141 u32 parent_ino; 142 u32 parent_gen; 143 } i32; 144 struct { 145 u64 ino; 146 u32 gen; 147 } __packed i64; 148 struct { 149 u32 block; 150 u16 partref; 151 u16 parent_partref; 152 u32 generation; 153 u32 parent_block; 154 u32 parent_generation; 155 } udf; 156 DECLARE_FLEX_ARRAY(__u32, raw); 157 }; 158 }; 159 160 #define EXPORT_FH_CONNECTABLE 0x1 /* Encode file handle with parent */ 161 #define EXPORT_FH_FID 0x2 /* File handle may be non-decodeable */ 162 #define EXPORT_FH_DIR_ONLY 0x4 /* Only decode file handle for a directory */ 163 164 /* 165 * Filesystems use only lower 8 bits of file_handle type for fid_type. 166 * name_to_handle_at() uses upper 16 bits of type as user flags to be 167 * interpreted by open_by_handle_at(). 168 */ 169 #define FILEID_USER_FLAGS_MASK 0xffff0000 170 #define FILEID_USER_FLAGS(type) ((type) & FILEID_USER_FLAGS_MASK) 171 172 /* Flags supported in encoded handle_type that is exported to user */ 173 #define FILEID_IS_CONNECTABLE 0x10000 174 #define FILEID_IS_DIR 0x20000 175 #define FILEID_VALID_USER_FLAGS (FILEID_IS_CONNECTABLE | FILEID_IS_DIR) 176 177 /** 178 * struct export_operations - for nfsd to communicate with file systems 179 * @encode_fh: encode a file handle fragment from a dentry 180 * @fh_to_dentry: find the implied object and get a dentry for it 181 * @fh_to_parent: find the implied object's parent and get a dentry for it 182 * @get_name: find the name for a given inode in a given directory 183 * @get_parent: find the parent of a given directory 184 * @commit_metadata: commit metadata changes to stable storage 185 * 186 * See Documentation/filesystems/nfs/exporting.rst for details on how to use 187 * this interface correctly. 188 * 189 * encode_fh: 190 * @encode_fh should store in the file handle fragment @fh (using at most 191 * @max_len bytes) information that can be used by @decode_fh to recover the 192 * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit 193 * set, the encode_fh() should store sufficient information so that a good 194 * attempt can be made to find not only the file but also it's place in the 195 * filesystem. This typically means storing a reference to de->d_parent in 196 * the filehandle fragment. encode_fh() should return the fileid_type on 197 * success and on error returns 255 (if the space needed to encode fh is 198 * greater than @max_len*4 bytes). On error @max_len contains the minimum 199 * size(in 4 byte unit) needed to encode the file handle. 200 * 201 * fh_to_dentry: 202 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 203 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 204 * to the same file that the file handle fragment refers to. If it cannot, 205 * it should return a %NULL pointer if the file cannot be found, or an 206 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred. 207 * Any other error code is treated like %NULL, and will cause an %ESTALE error 208 * for callers of exportfs_decode_fh(). 209 * Any suitable dentry can be returned including, if necessary, a new dentry 210 * created with d_alloc_root. The caller can then find any other extant 211 * dentries by following the d_alias links. 212 * 213 * fh_to_parent: 214 * Same as @fh_to_dentry, except that it returns a pointer to the parent 215 * dentry if it was encoded into the filehandle fragment by @encode_fh. 216 * 217 * get_name: 218 * @get_name should find a name for the given @child in the given @parent 219 * directory. The name should be stored in the @name (with the 220 * understanding that it is already pointing to a %NAME_MAX+1 sized 221 * buffer. get_name() should return %0 on success, a negative error code 222 * or error. @get_name will be called without @parent->i_mutex held. 223 * 224 * get_parent: 225 * @get_parent should find the parent directory for the given @child which 226 * is also a directory. In the event that it cannot be found, or storage 227 * space cannot be allocated, a %ERR_PTR should be returned. 228 * 229 * open: 230 * Allow filesystems to specify a custom open function. 231 * 232 * commit_metadata: 233 * @commit_metadata should commit metadata changes to stable storage. 234 * 235 * Locking rules: 236 * get_parent is called with child->d_inode->i_mutex down 237 * get_name is not (which is possibly inconsistent) 238 */ 239 240 struct export_operations { 241 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, 242 struct inode *parent); 243 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 244 int fh_len, int fh_type); 245 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 246 int fh_len, int fh_type); 247 int (*get_name)(struct dentry *parent, char *name, 248 struct dentry *child); 249 struct dentry * (*get_parent)(struct dentry *child); 250 int (*commit_metadata)(struct inode *inode); 251 252 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset); 253 int (*map_blocks)(struct inode *inode, loff_t offset, 254 u64 len, struct iomap *iomap, 255 bool write, u32 *device_generation); 256 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, 257 int nr_iomaps, struct iattr *iattr); 258 struct file * (*open)(struct path *path, unsigned int oflags); 259 #define EXPORT_OP_NOWCC (0x1) /* don't collect v3 wcc data */ 260 #define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */ 261 #define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */ 262 #define EXPORT_OP_REMOTE_FS (0x8) /* Filesystem is remote */ 263 #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply 264 atomic attribute updates 265 */ 266 #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */ 267 #define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */ 268 unsigned long flags; 269 }; 270 271 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, 272 int *max_len, struct inode *parent, 273 int flags); 274 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 275 int *max_len, int flags); 276 277 static inline bool exportfs_can_encode_fid(const struct export_operations *nop) 278 { 279 return !nop || nop->encode_fh; 280 } 281 282 static inline bool exportfs_can_decode_fh(const struct export_operations *nop) 283 { 284 return nop && nop->fh_to_dentry; 285 } 286 287 static inline bool exportfs_can_encode_fh(const struct export_operations *nop, 288 int fh_flags) 289 { 290 /* 291 * If a non-decodeable file handle was requested, we only need to make 292 * sure that filesystem did not opt-out of encoding fid. 293 */ 294 if (fh_flags & EXPORT_FH_FID) 295 return exportfs_can_encode_fid(nop); 296 297 /* 298 * If a decodeable file handle was requested, we need to make sure that 299 * filesystem can also decode file handles. 300 */ 301 return exportfs_can_decode_fh(nop); 302 } 303 304 static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid, 305 int *max_len) 306 { 307 return exportfs_encode_inode_fh(inode, fid, max_len, NULL, 308 EXPORT_FH_FID); 309 } 310 311 extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt, 312 struct fid *fid, int fh_len, 313 int fileid_type, 314 unsigned int flags, 315 int (*acceptable)(void *, struct dentry *), 316 void *context); 317 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 318 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 319 void *context); 320 321 /* 322 * Generic helpers for filesystems. 323 */ 324 int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, 325 struct inode *parent); 326 struct dentry *generic_fh_to_dentry(struct super_block *sb, 327 struct fid *fid, int fh_len, int fh_type, 328 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 329 struct dentry *generic_fh_to_parent(struct super_block *sb, 330 struct fid *fid, int fh_len, int fh_type, 331 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 332 333 #endif /* LINUX_EXPORTFS_H */ 334