1 #ifndef LINUX_EXPORTFS_H 2 #define LINUX_EXPORTFS_H 1 3 4 #include <linux/types.h> 5 6 struct dentry; 7 struct iattr; 8 struct inode; 9 struct iomap; 10 struct super_block; 11 struct vfsmount; 12 13 /* limit the handle size to NFSv4 handle size now */ 14 #define MAX_HANDLE_SZ 128 15 16 /* 17 * The fileid_type identifies how the file within the filesystem is encoded. 18 * In theory this is freely set and parsed by the filesystem, but we try to 19 * stick to conventions so we can share some generic code and don't confuse 20 * sniffers like ethereal/wireshark. 21 * 22 * The filesystem must not use the value '0' or '0xff'. 23 */ 24 enum fid_type { 25 /* 26 * The root, or export point, of the filesystem. 27 * (Never actually passed down to the filesystem. 28 */ 29 FILEID_ROOT = 0, 30 31 /* 32 * 32bit inode number, 32 bit generation number. 33 */ 34 FILEID_INO32_GEN = 1, 35 36 /* 37 * 32bit inode number, 32 bit generation number, 38 * 32 bit parent directory inode number. 39 */ 40 FILEID_INO32_GEN_PARENT = 2, 41 42 /* 43 * 64 bit object ID, 64 bit root object ID, 44 * 32 bit generation number. 45 */ 46 FILEID_BTRFS_WITHOUT_PARENT = 0x4d, 47 48 /* 49 * 64 bit object ID, 64 bit root object ID, 50 * 32 bit generation number, 51 * 64 bit parent object ID, 32 bit parent generation. 52 */ 53 FILEID_BTRFS_WITH_PARENT = 0x4e, 54 55 /* 56 * 64 bit object ID, 64 bit root object ID, 57 * 32 bit generation number, 58 * 64 bit parent object ID, 32 bit parent generation, 59 * 64 bit parent root object ID. 60 */ 61 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f, 62 63 /* 64 * 32 bit block number, 16 bit partition reference, 65 * 16 bit unused, 32 bit generation number. 66 */ 67 FILEID_UDF_WITHOUT_PARENT = 0x51, 68 69 /* 70 * 32 bit block number, 16 bit partition reference, 71 * 16 bit unused, 32 bit generation number, 72 * 32 bit parent block number, 32 bit parent generation number 73 */ 74 FILEID_UDF_WITH_PARENT = 0x52, 75 76 /* 77 * 64 bit checkpoint number, 64 bit inode number, 78 * 32 bit generation number. 79 */ 80 FILEID_NILFS_WITHOUT_PARENT = 0x61, 81 82 /* 83 * 64 bit checkpoint number, 64 bit inode number, 84 * 32 bit generation number, 32 bit parent generation. 85 * 64 bit parent inode number. 86 */ 87 FILEID_NILFS_WITH_PARENT = 0x62, 88 89 /* 90 * 32 bit generation number, 40 bit i_pos. 91 */ 92 FILEID_FAT_WITHOUT_PARENT = 0x71, 93 94 /* 95 * 32 bit generation number, 40 bit i_pos, 96 * 32 bit parent generation number, 40 bit parent i_pos 97 */ 98 FILEID_FAT_WITH_PARENT = 0x72, 99 100 /* 101 * 128 bit child FID (struct lu_fid) 102 * 128 bit parent FID (struct lu_fid) 103 */ 104 FILEID_LUSTRE = 0x97, 105 106 /* 107 * Filesystems must not use 0xff file ID. 108 */ 109 FILEID_INVALID = 0xff, 110 }; 111 112 struct fid { 113 union { 114 struct { 115 u32 ino; 116 u32 gen; 117 u32 parent_ino; 118 u32 parent_gen; 119 } i32; 120 struct { 121 u32 block; 122 u16 partref; 123 u16 parent_partref; 124 u32 generation; 125 u32 parent_block; 126 u32 parent_generation; 127 } udf; 128 __u32 raw[0]; 129 }; 130 }; 131 132 /** 133 * struct export_operations - for nfsd to communicate with file systems 134 * @encode_fh: encode a file handle fragment from a dentry 135 * @fh_to_dentry: find the implied object and get a dentry for it 136 * @fh_to_parent: find the implied object's parent and get a dentry for it 137 * @get_name: find the name for a given inode in a given directory 138 * @get_parent: find the parent of a given directory 139 * @commit_metadata: commit metadata changes to stable storage 140 * 141 * See Documentation/filesystems/nfs/Exporting for details on how to use 142 * this interface correctly. 143 * 144 * encode_fh: 145 * @encode_fh should store in the file handle fragment @fh (using at most 146 * @max_len bytes) information that can be used by @decode_fh to recover the 147 * file referred to by the &struct dentry @de. If the @connectable flag is 148 * set, the encode_fh() should store sufficient information so that a good 149 * attempt can be made to find not only the file but also it's place in the 150 * filesystem. This typically means storing a reference to de->d_parent in 151 * the filehandle fragment. encode_fh() should return the fileid_type on 152 * success and on error returns 255 (if the space needed to encode fh is 153 * greater than @max_len*4 bytes). On error @max_len contains the minimum 154 * size(in 4 byte unit) needed to encode the file handle. 155 * 156 * fh_to_dentry: 157 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 158 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 159 * to the same file that the file handle fragment refers to. If it cannot, 160 * it should return a %NULL pointer if the file cannot be found, or an 161 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred. 162 * Any other error code is treated like %NULL, and will cause an %ESTALE error 163 * for callers of exportfs_decode_fh(). 164 * Any suitable dentry can be returned including, if necessary, a new dentry 165 * created with d_alloc_root. The caller can then find any other extant 166 * dentries by following the d_alias links. 167 * 168 * fh_to_parent: 169 * Same as @fh_to_dentry, except that it returns a pointer to the parent 170 * dentry if it was encoded into the filehandle fragment by @encode_fh. 171 * 172 * get_name: 173 * @get_name should find a name for the given @child in the given @parent 174 * directory. The name should be stored in the @name (with the 175 * understanding that it is already pointing to a a %NAME_MAX+1 sized 176 * buffer. get_name() should return %0 on success, a negative error code 177 * or error. @get_name will be called without @parent->i_mutex held. 178 * 179 * get_parent: 180 * @get_parent should find the parent directory for the given @child which 181 * is also a directory. In the event that it cannot be found, or storage 182 * space cannot be allocated, a %ERR_PTR should be returned. 183 * 184 * commit_metadata: 185 * @commit_metadata should commit metadata changes to stable storage. 186 * 187 * Locking rules: 188 * get_parent is called with child->d_inode->i_mutex down 189 * get_name is not (which is possibly inconsistent) 190 */ 191 192 struct export_operations { 193 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, 194 struct inode *parent); 195 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 196 int fh_len, int fh_type); 197 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 198 int fh_len, int fh_type); 199 int (*get_name)(struct dentry *parent, char *name, 200 struct dentry *child); 201 struct dentry * (*get_parent)(struct dentry *child); 202 int (*commit_metadata)(struct inode *inode); 203 204 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset); 205 int (*map_blocks)(struct inode *inode, loff_t offset, 206 u64 len, struct iomap *iomap, 207 bool write, u32 *device_generation); 208 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, 209 int nr_iomaps, struct iattr *iattr); 210 }; 211 212 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, 213 int *max_len, struct inode *parent); 214 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 215 int *max_len, int connectable); 216 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 217 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 218 void *context); 219 220 /* 221 * Generic helpers for filesystems. 222 */ 223 extern struct dentry *generic_fh_to_dentry(struct super_block *sb, 224 struct fid *fid, int fh_len, int fh_type, 225 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 226 extern struct dentry *generic_fh_to_parent(struct super_block *sb, 227 struct fid *fid, int fh_len, int fh_type, 228 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 229 230 #endif /* LINUX_EXPORTFS_H */ 231