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TOMOYO Linux Cross Reference
Linux/include/linux/exportfs.h

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  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 /* limit the handle size to NFSv4 handle size now */
 12 #define MAX_HANDLE_SZ 128
 13 
 14 /*
 15  * The fileid_type identifies how the file within the filesystem is encoded.
 16  * In theory this is freely set and parsed by the filesystem, but we try to
 17  * stick to conventions so we can share some generic code and don't confuse
 18  * sniffers like ethereal/wireshark.
 19  *
 20  * The filesystem must not use the value '' or '0xff'.
 21  */
 22 enum fid_type {
 23         /*
 24          * The root, or export point, of the filesystem.
 25          * (Never actually passed down to the filesystem.
 26          */
 27         FILEID_ROOT = 0,
 28 
 29         /*
 30          * 32bit inode number, 32 bit generation number.
 31          */
 32         FILEID_INO32_GEN = 1,
 33 
 34         /*
 35          * 32bit inode number, 32 bit generation number,
 36          * 32 bit parent directory inode number.
 37          */
 38         FILEID_INO32_GEN_PARENT = 2,
 39 
 40         /*
 41          * 64 bit object ID, 64 bit root object ID,
 42          * 32 bit generation number.
 43          */
 44         FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
 45 
 46         /*
 47          * 64 bit object ID, 64 bit root object ID,
 48          * 32 bit generation number,
 49          * 64 bit parent object ID, 32 bit parent generation.
 50          */
 51         FILEID_BTRFS_WITH_PARENT = 0x4e,
 52 
 53         /*
 54          * 64 bit object ID, 64 bit root object ID,
 55          * 32 bit generation number,
 56          * 64 bit parent object ID, 32 bit parent generation,
 57          * 64 bit parent root object ID.
 58          */
 59         FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
 60 
 61         /*
 62          * 32 bit block number, 16 bit partition reference,
 63          * 16 bit unused, 32 bit generation number.
 64          */
 65         FILEID_UDF_WITHOUT_PARENT = 0x51,
 66 
 67         /*
 68          * 32 bit block number, 16 bit partition reference,
 69          * 16 bit unused, 32 bit generation number,
 70          * 32 bit parent block number, 32 bit parent generation number
 71          */
 72         FILEID_UDF_WITH_PARENT = 0x52,
 73 
 74         /*
 75          * 64 bit checkpoint number, 64 bit inode number,
 76          * 32 bit generation number.
 77          */
 78         FILEID_NILFS_WITHOUT_PARENT = 0x61,
 79 
 80         /*
 81          * 64 bit checkpoint number, 64 bit inode number,
 82          * 32 bit generation number, 32 bit parent generation.
 83          * 64 bit parent inode number.
 84          */
 85         FILEID_NILFS_WITH_PARENT = 0x62,
 86 
 87         /*
 88          * 32 bit generation number, 40 bit i_pos.
 89          */
 90         FILEID_FAT_WITHOUT_PARENT = 0x71,
 91 
 92         /*
 93          * 32 bit generation number, 40 bit i_pos,
 94          * 32 bit parent generation number, 40 bit parent i_pos
 95          */
 96         FILEID_FAT_WITH_PARENT = 0x72,
 97 
 98         /*
 99          * Filesystems must not use 0xff file ID.
100          */
101         FILEID_INVALID = 0xff,
102 };
103 
104 struct fid {
105         union {
106                 struct {
107                         u32 ino;
108                         u32 gen;
109                         u32 parent_ino;
110                         u32 parent_gen;
111                 } i32;
112                 struct {
113                         u32 block;
114                         u16 partref;
115                         u16 parent_partref;
116                         u32 generation;
117                         u32 parent_block;
118                         u32 parent_generation;
119                 } udf;
120                 __u32 raw[0];
121         };
122 };
123 
124 /**
125  * struct export_operations - for nfsd to communicate with file systems
126  * @encode_fh:      encode a file handle fragment from a dentry
127  * @fh_to_dentry:   find the implied object and get a dentry for it
128  * @fh_to_parent:   find the implied object's parent and get a dentry for it
129  * @get_name:       find the name for a given inode in a given directory
130  * @get_parent:     find the parent of a given directory
131  * @commit_metadata: commit metadata changes to stable storage
132  *
133  * See Documentation/filesystems/nfs/Exporting for details on how to use
134  * this interface correctly.
135  *
136  * encode_fh:
137  *    @encode_fh should store in the file handle fragment @fh (using at most
138  *    @max_len bytes) information that can be used by @decode_fh to recover the
139  *    file referred to by the &struct dentry @de.  If the @connectable flag is
140  *    set, the encode_fh() should store sufficient information so that a good
141  *    attempt can be made to find not only the file but also it's place in the
142  *    filesystem.   This typically means storing a reference to de->d_parent in
143  *    the filehandle fragment.  encode_fh() should return the fileid_type on
144  *    success and on error returns 255 (if the space needed to encode fh is
145  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
146  *    size(in 4 byte unit) needed to encode the file handle.
147  *
148  * fh_to_dentry:
149  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
150  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
151  *    to the same file that the file handle fragment refers to.  If it cannot,
152  *    it should return a %NULL pointer if the file was found but no acceptable
153  *    &dentries were available, or an %ERR_PTR error code indicating why it
154  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
155  *    returned including, if necessary, a new dentry created with d_alloc_root.
156  *    The caller can then find any other extant dentries by following the
157  *    d_alias links.
158  *
159  * fh_to_parent:
160  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
161  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
162  *
163  * get_name:
164  *    @get_name should find a name for the given @child in the given @parent
165  *    directory.  The name should be stored in the @name (with the
166  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
167  *    buffer.   get_name() should return %0 on success, a negative error code
168  *    or error.  @get_name will be called without @parent->i_mutex held.
169  *
170  * get_parent:
171  *    @get_parent should find the parent directory for the given @child which
172  *    is also a directory.  In the event that it cannot be found, or storage
173  *    space cannot be allocated, a %ERR_PTR should be returned.
174  *
175  * commit_metadata:
176  *    @commit_metadata should commit metadata changes to stable storage.
177  *
178  * Locking rules:
179  *    get_parent is called with child->d_inode->i_mutex down
180  *    get_name is not (which is possibly inconsistent)
181  */
182 
183 struct export_operations {
184         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
185                         struct inode *parent);
186         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
187                         int fh_len, int fh_type);
188         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
189                         int fh_len, int fh_type);
190         int (*get_name)(struct dentry *parent, char *name,
191                         struct dentry *child);
192         struct dentry * (*get_parent)(struct dentry *child);
193         int (*commit_metadata)(struct inode *inode);
194 };
195 
196 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
197                                     int *max_len, struct inode *parent);
198 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
199         int *max_len, int connectable);
200 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
201         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
202         void *context);
203 
204 /*
205  * Generic helpers for filesystems.
206  */
207 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
208         struct fid *fid, int fh_len, int fh_type,
209         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
210 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
211         struct fid *fid, int fh_len, int fh_type,
212         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
213 
214 #endif /* LINUX_EXPORTFS_H */
215 

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