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