1 #ifndef LINUX_EXPORTFS_H 2 #define LINUX_EXPORTFS_H 1 3 4 #include <linux/types.h> 5 6 struct dentry; 7 struct inode; 8 struct super_block; 9 struct vfsmount; 10 11 /* limit the handle size to NFSv4 handle size now */ 12 #define MAX_HANDLE_SZ 128 13 14 /* 15 * The fileid_type identifies how the file within the filesystem is encoded. 16 * In theory this is freely set and parsed by the filesystem, but we try to 17 * stick to conventions so we can share some generic code and don't confuse 18 * sniffers like ethereal/wireshark. 19 * 20 * The filesystem must not use the value '0' or '0xff'. 21 */ 22 enum fid_type { 23 /* 24 * The root, or export point, of the filesystem. 25 * (Never actually passed down to the filesystem. 26 */ 27 FILEID_ROOT = 0, 28 29 /* 30 * 32bit inode number, 32 bit generation number. 31 */ 32 FILEID_INO32_GEN = 1, 33 34 /* 35 * 32bit inode number, 32 bit generation number, 36 * 32 bit parent directory inode number. 37 */ 38 FILEID_INO32_GEN_PARENT = 2, 39 40 /* 41 * 64 bit object ID, 64 bit root object ID, 42 * 32 bit generation number. 43 */ 44 FILEID_BTRFS_WITHOUT_PARENT = 0x4d, 45 46 /* 47 * 64 bit object ID, 64 bit root object ID, 48 * 32 bit generation number, 49 * 64 bit parent object ID, 32 bit parent generation. 50 */ 51 FILEID_BTRFS_WITH_PARENT = 0x4e, 52 53 /* 54 * 64 bit object ID, 64 bit root object ID, 55 * 32 bit generation number, 56 * 64 bit parent object ID, 32 bit parent generation, 57 * 64 bit parent root object ID. 58 */ 59 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f, 60 61 /* 62 * 32 bit block number, 16 bit partition reference, 63 * 16 bit unused, 32 bit generation number. 64 */ 65 FILEID_UDF_WITHOUT_PARENT = 0x51, 66 67 /* 68 * 32 bit block number, 16 bit partition reference, 69 * 16 bit unused, 32 bit generation number, 70 * 32 bit parent block number, 32 bit parent generation number 71 */ 72 FILEID_UDF_WITH_PARENT = 0x52, 73 74 /* 75 * 64 bit checkpoint number, 64 bit inode number, 76 * 32 bit generation number. 77 */ 78 FILEID_NILFS_WITHOUT_PARENT = 0x61, 79 80 /* 81 * 64 bit checkpoint number, 64 bit inode number, 82 * 32 bit generation number, 32 bit parent generation. 83 * 64 bit parent inode number. 84 */ 85 FILEID_NILFS_WITH_PARENT = 0x62, 86 }; 87 88 struct fid { 89 union { 90 struct { 91 u32 ino; 92 u32 gen; 93 u32 parent_ino; 94 u32 parent_gen; 95 } i32; 96 struct { 97 u32 block; 98 u16 partref; 99 u16 parent_partref; 100 u32 generation; 101 u32 parent_block; 102 u32 parent_generation; 103 } udf; 104 __u32 raw[0]; 105 }; 106 }; 107 108 /** 109 * struct export_operations - for nfsd to communicate with file systems 110 * @encode_fh: encode a file handle fragment from a dentry 111 * @fh_to_dentry: find the implied object and get a dentry for it 112 * @fh_to_parent: find the implied object's parent and get a dentry for it 113 * @get_name: find the name for a given inode in a given directory 114 * @get_parent: find the parent of a given directory 115 * @commit_metadata: commit metadata changes to stable storage 116 * 117 * See Documentation/filesystems/nfs/Exporting for details on how to use 118 * this interface correctly. 119 * 120 * encode_fh: 121 * @encode_fh should store in the file handle fragment @fh (using at most 122 * @max_len bytes) information that can be used by @decode_fh to recover the 123 * file referred to by the &struct dentry @de. If the @connectable flag is 124 * set, the encode_fh() should store sufficient information so that a good 125 * attempt can be made to find not only the file but also it's place in the 126 * filesystem. This typically means storing a reference to de->d_parent in 127 * the filehandle fragment. encode_fh() should return the fileid_type on 128 * success and on error returns 255 (if the space needed to encode fh is 129 * greater than @max_len*4 bytes). On error @max_len contains the minimum 130 * size(in 4 byte unit) needed to encode the file handle. 131 * 132 * fh_to_dentry: 133 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 134 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 135 * to the same file that the file handle fragment refers to. If it cannot, 136 * it should return a %NULL pointer if the file was found but no acceptable 137 * &dentries were available, or an %ERR_PTR error code indicating why it 138 * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be 139 * returned including, if necessary, a new dentry created with d_alloc_root. 140 * The caller can then find any other extant dentries by following the 141 * d_alias links. 142 * 143 * fh_to_parent: 144 * Same as @fh_to_dentry, except that it returns a pointer to the parent 145 * dentry if it was encoded into the filehandle fragment by @encode_fh. 146 * 147 * get_name: 148 * @get_name should find a name for the given @child in the given @parent 149 * directory. The name should be stored in the @name (with the 150 * understanding that it is already pointing to a a %NAME_MAX+1 sized 151 * buffer. get_name() should return %0 on success, a negative error code 152 * or error. @get_name will be called without @parent->i_mutex held. 153 * 154 * get_parent: 155 * @get_parent should find the parent directory for the given @child which 156 * is also a directory. In the event that it cannot be found, or storage 157 * space cannot be allocated, a %ERR_PTR should be returned. 158 * 159 * commit_metadata: 160 * @commit_metadata should commit metadata changes to stable storage. 161 * 162 * Locking rules: 163 * get_parent is called with child->d_inode->i_mutex down 164 * get_name is not (which is possibly inconsistent) 165 */ 166 167 struct export_operations { 168 int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len, 169 int connectable); 170 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 171 int fh_len, int fh_type); 172 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 173 int fh_len, int fh_type); 174 int (*get_name)(struct dentry *parent, char *name, 175 struct dentry *child); 176 struct dentry * (*get_parent)(struct dentry *child); 177 int (*commit_metadata)(struct inode *inode); 178 }; 179 180 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 181 int *max_len, int connectable); 182 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 183 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 184 void *context); 185 186 /* 187 * Generic helpers for filesystems. 188 */ 189 extern struct dentry *generic_fh_to_dentry(struct super_block *sb, 190 struct fid *fid, int fh_len, int fh_type, 191 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 192 extern struct dentry *generic_fh_to_parent(struct super_block *sb, 193 struct fid *fid, int fh_len, int fh_type, 194 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 195 196 #endif /* LINUX_EXPORTFS_H */ 197