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a5694255 CH |
1 | #ifndef LINUX_EXPORTFS_H |
2 | #define LINUX_EXPORTFS_H 1 | |
3 | ||
4 | #include <linux/types.h> | |
5 | ||
6 | struct dentry; | |
2596110a | 7 | struct inode; |
a5694255 | 8 | struct super_block; |
d37065cd | 9 | struct vfsmount; |
a5694255 | 10 | |
6e91ea2b CH |
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 | }; | |
a5694255 CH |
49 | |
50 | /** | |
51 | * struct export_operations - for nfsd to communicate with file systems | |
52 | * @decode_fh: decode a file handle fragment and return a &struct dentry | |
53 | * @encode_fh: encode a file handle fragment from a dentry | |
54 | * @get_name: find the name for a given inode in a given directory | |
55 | * @get_parent: find the parent of a given directory | |
56 | * @get_dentry: find a dentry for the inode given a file handle sub-fragment | |
a5694255 | 57 | * |
e38f9817 CH |
58 | * See Documentation/filesystems/Exporting for details on how to use |
59 | * this interface correctly. | |
a5694255 | 60 | * |
a5694255 CH |
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 | * | |
2596110a CH |
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 | * | |
a5694255 CH |
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 | * | |
a5694255 CH |
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 { | |
a5694255 CH |
104 | int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len, |
105 | int connectable); | |
2596110a CH |
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); | |
a5694255 CH |
110 | int (*get_name)(struct dentry *parent, char *name, |
111 | struct dentry *child); | |
112 | struct dentry * (*get_parent)(struct dentry *child); | |
a5694255 CH |
113 | }; |
114 | ||
6e91ea2b CH |
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, | |
d37065cd CH |
118 | int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), |
119 | void *context); | |
120 | ||
2596110a CH |
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 | ||
a5694255 | 131 | #endif /* LINUX_EXPORTFS_H */ |