1#ifndef LINUX_EXPORTFS_H 2#define LINUX_EXPORTFS_H 1 3 4#include <linux/types.h> 5 6struct dentry; 7struct inode; 8struct super_block; 9struct 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 */ 19enum 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 * 32 bit block number, 16 bit partition reference, 39 * 16 bit unused, 32 bit generation number. 40 */ 41 FILEID_UDF_WITHOUT_PARENT = 0x51, 42 43 /* 44 * 32 bit block number, 16 bit partition reference, 45 * 16 bit unused, 32 bit generation number, 46 * 32 bit parent block number, 32 bit parent generation number 47 */ 48 FILEID_UDF_WITH_PARENT = 0x52, 49}; 50 51struct fid { 52 union { 53 struct { 54 u32 ino; 55 u32 gen; 56 u32 parent_ino; 57 u32 parent_gen; 58 } i32; 59 struct { 60 u32 block; 61 u16 partref; 62 u16 parent_partref; 63 u32 generation; 64 u32 parent_block; 65 u32 parent_generation; 66 } udf; 67 __u32 raw[0]; 68 }; 69}; 70 71/** 72 * struct export_operations - for nfsd to communicate with file systems 73 * @encode_fh: encode a file handle fragment from a dentry 74 * @fh_to_dentry: find the implied object and get a dentry for it 75 * @fh_to_parent: find the implied object's parent and get a dentry for it 76 * @get_name: find the name for a given inode in a given directory 77 * @get_parent: find the parent of a given directory 78 * 79 * See Documentation/filesystems/Exporting for details on how to use 80 * this interface correctly. 81 * 82 * encode_fh: 83 * @encode_fh should store in the file handle fragment @fh (using at most 84 * @max_len bytes) information that can be used by @decode_fh to recover the 85 * file refered to by the &struct dentry @de. If the @connectable flag is 86 * set, the encode_fh() should store sufficient information so that a good 87 * attempt can be made to find not only the file but also it's place in the 88 * filesystem. This typically means storing a reference to de->d_parent in 89 * the filehandle fragment. encode_fh() should return the number of bytes 90 * stored or a negative error code such as %-ENOSPC 91 * 92 * fh_to_dentry: 93 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle 94 * fragment (@fh, @fh_len). It should return a &struct dentry which refers 95 * to the same file that the file handle fragment refers to. If it cannot, 96 * it should return a %NULL pointer if the file was found but no acceptable 97 * &dentries were available, or an %ERR_PTR error code indicating why it 98 * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be 99 * returned including, if necessary, a new dentry created with d_alloc_root. 100 * The caller can then find any other extant dentries by following the 101 * d_alias links. 102 * 103 * fh_to_parent: 104 * Same as @fh_to_dentry, except that it returns a pointer to the parent 105 * dentry if it was encoded into the filehandle fragment by @encode_fh. 106 * 107 * get_name: 108 * @get_name should find a name for the given @child in the given @parent 109 * directory. The name should be stored in the @name (with the 110 * understanding that it is already pointing to a a %NAME_MAX+1 sized 111 * buffer. get_name() should return %0 on success, a negative error code 112 * or error. @get_name will be called without @parent->i_mutex held. 113 * 114 * get_parent: 115 * @get_parent should find the parent directory for the given @child which 116 * is also a directory. In the event that it cannot be found, or storage 117 * space cannot be allocated, a %ERR_PTR should be returned. 118 * 119 * Locking rules: 120 * get_parent is called with child->d_inode->i_mutex down 121 * get_name is not (which is possibly inconsistent) 122 */ 123 124struct export_operations { 125 int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len, 126 int connectable); 127 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, 128 int fh_len, int fh_type); 129 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, 130 int fh_len, int fh_type); 131 int (*get_name)(struct dentry *parent, char *name, 132 struct dentry *child); 133 struct dentry * (*get_parent)(struct dentry *child); 134}; 135 136extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, 137 int *max_len, int connectable); 138extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, 139 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), 140 void *context); 141 142/* 143 * Generic helpers for filesystems. 144 */ 145extern struct dentry *generic_fh_to_dentry(struct super_block *sb, 146 struct fid *fid, int fh_len, int fh_type, 147 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 148extern struct dentry *generic_fh_to_parent(struct super_block *sb, 149 struct fid *fid, int fh_len, int fh_type, 150 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); 151 152#endif /* LINUX_EXPORTFS_H */ 153