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