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 * 128 bit child FID (struct lu_fid) 103 * 128 bit parent FID (struct lu_fid) 104 */ 105 FILEID_LUSTRE = 0x97, 106 107 /* 108 * 64 bit unique kernfs id 109 */ 110 FILEID_KERNFS = 0xfe, 111 112 /* 113 * Filesystems must not use 0xff file ID. 114 */ 115 FILEID_INVALID = 0xff, 116 }; 117 118 struct fid { 119 union { 120 struct { 121 u32 ino; 122 u32 gen; 123 u32 parent_ino; 124 u32 parent_gen; 125 } i32; 126 struct { 127 u32 block; 128 u16 partref; 129 u16 parent_partref; 130 u32 generation; 131 u32 parent_block; 132 u32 parent_generation; 133 } udf; 134 __u32 raw[0]; 135 }; 136 }; 137 138 /** 139 * struct export_operations - for nfsd to communicate with file systems 140 * @encode_fh: encode a file handle fragment from a dentry 141 * @fh_to_dentry: find the implied object and get a dentry for it 142 * @fh_to_parent: find the implied object's parent and get a dentry for it 143 * @get_name: find the name for a given inode in a given directory 144 * @get_parent: find the parent of a given directory 145 * @commit_metadata: commit metadata changes to stable storage 146 * 147 * See Documentation/filesystems/nfs/exporting.rst for details on how to use 148 * this interface correctly. 149 * 150 * encode_fh: 151 * @encode_fh should store in the file handle fragment @fh (using at most 152 * @max_len bytes) information that can be used by @decode_fh to recover the 153 * file referred to by the &struct dentry @de. If the @connectable flag is 154 * set, the encode_fh() should store sufficient information so that a good 155 * attempt can be made to find not only the file but also it's place in the 156 * filesystem. This typically means storing a reference to de->d_parent in 157 * the filehandle fragment. encode_fh() should return the fileid_type on 158 * success and on error returns 255 (if the space needed to encode fh is 159 * greater than @max_len*4 bytes). On error @max_len contains the minimum 160 * size(in 4 byte unit) needed to encode the file handle. 161 * 162 * fh_to_dentry: 163 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 164 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 165 * to the same file that the file handle fragment refers to. If it cannot, 166 * it should return a %NULL pointer if the file cannot be found, or an 167 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred. 168 * Any other error code is treated like %NULL, and will cause an %ESTALE error 169 * for callers of exportfs_decode_fh(). 170 * Any suitable dentry can be returned including, if necessary, a new dentry 171 * created with d_alloc_root. The caller can then find any other extant 172 * dentries by following the d_alias links. 173 * 174 * fh_to_parent: 175 * Same as @fh_to_dentry, except that it returns a pointer to the parent 176 * dentry if it was encoded into the filehandle fragment by @encode_fh. 177 * 178 * get_name: 179 * @get_name should find a name for the given @child in the given @parent 180 * directory. The name should be stored in the @name (with the 181 * understanding that it is already pointing to a %NAME_MAX+1 sized 182 * buffer. get_name() should return %0 on success, a negative error code 183 * or error. @get_name will be called without @parent->i_mutex held. 184 * 185 * get_parent: 186 * @get_parent should find the parent directory for the given @child which 187 * is also a directory. In the event that it cannot be found, or storage 188 * space cannot be allocated, a %ERR_PTR should be returned. 189 * 190 * commit_metadata: 191 * @commit_metadata should commit metadata changes to stable storage. 192 * 193 * Locking rules: 194 * get_parent is called with child->d_inode->i_mutex down 195 * get_name is not (which is possibly inconsistent) 196 */ 197 198 struct export_operations { 199 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, 200 struct inode *parent); 201 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 202 int fh_len, int fh_type); 203 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 204 int fh_len, int fh_type); 205 int (*get_name)(struct dentry *parent, char *name, 206 struct dentry *child); 207 struct dentry * (*get_parent)(struct dentry *child); 208 int (*commit_metadata)(struct inode *inode); 209 210 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset); 211 int (*map_blocks)(struct inode *inode, loff_t offset, 212 u64 len, struct iomap *iomap, 213 bool write, u32 *device_generation); 214 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, 215 int nr_iomaps, struct iattr *iattr); 216 }; 217 218 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, 219 int *max_len, struct inode *parent); 220 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 221 int *max_len, int connectable); 222 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 223 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 224 void *context); 225 226 /* 227 * Generic helpers for filesystems. 228 */ 229 extern struct dentry *generic_fh_to_dentry(struct super_block *sb, 230 struct fid *fid, int fh_len, int fh_type, 231 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 232 extern struct dentry *generic_fh_to_parent(struct super_block *sb, 233 struct fid *fid, int fh_len, int fh_type, 234 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 235 236 #endif /* LINUX_EXPORTFS_H */ 237