1 #ifndef LINUX_EXPORTFS_H
2 #define LINUX_EXPORTFS_H 1
4 #include <linux/types.h>
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.
17 * The filesystem must not use the value '0' or '0xff'.
21 * The root, or export point, of the filesystem.
22 * (Never actually passed down to the filesystem.
27 * 32bit inode number, 32 bit generation number.
32 * 32bit inode number, 32 bit generation number,
33 * 32 bit parent directory inode number.
35 FILEID_INO32_GEN_PARENT = 2,
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
58 * See Documentation/filesystems/Exporting for details on how to use
59 * this interface correctly.
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
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
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.
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.
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.
99 * get_parent is called with child->d_inode->i_mutex down
100 * get_name is not (which is possibly inconsistent)
103 struct export_operations {
104 int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
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);
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 *),
122 * Generic helpers for filesystems.
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));
131 #endif /* LINUX_EXPORTFS_H */