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 7struct dentry; 8struct iattr; 9struct inode; 10struct iomap; 11struct super_block; 12struct 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 */ 25enum 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 135struct 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 222struct 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 */ 259static inline bool 260exportfs_lock_op_is_async(const struct export_operations *export_ops) 261{ 262 return export_ops->flags & EXPORT_OP_ASYNC_LOCK; 263} 264 265extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, 266 int *max_len, struct inode *parent, 267 int flags); 268extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 269 int *max_len, int flags); 270 271static inline bool exportfs_can_encode_fid(const struct export_operations *nop) 272{ 273 return !nop || nop->encode_fh; 274} 275 276static inline bool exportfs_can_decode_fh(const struct export_operations *nop) 277{ 278 return nop && nop->fh_to_dentry; 279} 280 281static 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 298static 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 305extern 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); 310extern 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 */ 317int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, 318 struct inode *parent); 319struct 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)); 322struct 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