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