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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 iattr;
  8 struct inode;
  9 struct super_block;
 10 struct vfsmount;
 11 
 12 /* limit the handle size to NFSv4 handle size now */
 13 #define MAX_HANDLE_SZ 128
 14 
 15 /*
 16  * The fileid_type identifies how the file within the filesystem is encoded.
 17  * In theory this is freely set and parsed by the filesystem, but we try to
 18  * stick to conventions so we can share some generic code and don't confuse
 19  * sniffers like ethereal/wireshark.
 20  *
 21  * The filesystem must not use the value '' or '0xff'.
 22  */
 23 enum fid_type {
 24         /*
 25          * The root, or export point, of the filesystem.
 26          * (Never actually passed down to the filesystem.
 27          */
 28         FILEID_ROOT = 0,
 29 
 30         /*
 31          * 32bit inode number, 32 bit generation number.
 32          */
 33         FILEID_INO32_GEN = 1,
 34 
 35         /*
 36          * 32bit inode number, 32 bit generation number,
 37          * 32 bit parent directory inode number.
 38          */
 39         FILEID_INO32_GEN_PARENT = 2,
 40 
 41         /*
 42          * 64 bit object ID, 64 bit root object ID,
 43          * 32 bit generation number.
 44          */
 45         FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
 46 
 47         /*
 48          * 64 bit object ID, 64 bit root object ID,
 49          * 32 bit generation number,
 50          * 64 bit parent object ID, 32 bit parent generation.
 51          */
 52         FILEID_BTRFS_WITH_PARENT = 0x4e,
 53 
 54         /*
 55          * 64 bit object ID, 64 bit root object ID,
 56          * 32 bit generation number,
 57          * 64 bit parent object ID, 32 bit parent generation,
 58          * 64 bit parent root object ID.
 59          */
 60         FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
 61 
 62         /*
 63          * 32 bit block number, 16 bit partition reference,
 64          * 16 bit unused, 32 bit generation number.
 65          */
 66         FILEID_UDF_WITHOUT_PARENT = 0x51,
 67 
 68         /*
 69          * 32 bit block number, 16 bit partition reference,
 70          * 16 bit unused, 32 bit generation number,
 71          * 32 bit parent block number, 32 bit parent generation number
 72          */
 73         FILEID_UDF_WITH_PARENT = 0x52,
 74 
 75         /*
 76          * 64 bit checkpoint number, 64 bit inode number,
 77          * 32 bit generation number.
 78          */
 79         FILEID_NILFS_WITHOUT_PARENT = 0x61,
 80 
 81         /*
 82          * 64 bit checkpoint number, 64 bit inode number,
 83          * 32 bit generation number, 32 bit parent generation.
 84          * 64 bit parent inode number.
 85          */
 86         FILEID_NILFS_WITH_PARENT = 0x62,
 87 
 88         /*
 89          * 32 bit generation number, 40 bit i_pos.
 90          */
 91         FILEID_FAT_WITHOUT_PARENT = 0x71,
 92 
 93         /*
 94          * 32 bit generation number, 40 bit i_pos,
 95          * 32 bit parent generation number, 40 bit parent i_pos
 96          */
 97         FILEID_FAT_WITH_PARENT = 0x72,
 98 
 99         /*
100          * Filesystems must not use 0xff file ID.
101          */
102         FILEID_INVALID = 0xff,
103 };
104 
105 struct fid {
106         union {
107                 struct {
108                         u32 ino;
109                         u32 gen;
110                         u32 parent_ino;
111                         u32 parent_gen;
112                 } i32;
113                 struct {
114                         u32 block;
115                         u16 partref;
116                         u16 parent_partref;
117                         u32 generation;
118                         u32 parent_block;
119                         u32 parent_generation;
120                 } udf;
121                 __u32 raw[0];
122         };
123 };
124 
125 /**
126  * struct export_operations - for nfsd to communicate with file systems
127  * @encode_fh:      encode a file handle fragment from a dentry
128  * @fh_to_dentry:   find the implied object and get a dentry for it
129  * @fh_to_parent:   find the implied object's parent and get a dentry for it
130  * @get_name:       find the name for a given inode in a given directory
131  * @get_parent:     find the parent of a given directory
132  * @commit_metadata: commit metadata changes to stable storage
133  *
134  * See Documentation/filesystems/nfs/Exporting for details on how to use
135  * this interface correctly.
136  *
137  * encode_fh:
138  *    @encode_fh should store in the file handle fragment @fh (using at most
139  *    @max_len bytes) information that can be used by @decode_fh to recover the
140  *    file referred to by the &struct dentry @de.  If the @connectable flag is
141  *    set, the encode_fh() should store sufficient information so that a good
142  *    attempt can be made to find not only the file but also it's place in the
143  *    filesystem.   This typically means storing a reference to de->d_parent in
144  *    the filehandle fragment.  encode_fh() should return the fileid_type on
145  *    success and on error returns 255 (if the space needed to encode fh is
146  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
147  *    size(in 4 byte unit) needed to encode the file handle.
148  *
149  * fh_to_dentry:
150  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
151  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
152  *    to the same file that the file handle fragment refers to.  If it cannot,
153  *    it should return a %NULL pointer if the file was found but no acceptable
154  *    &dentries were available, or an %ERR_PTR error code indicating why it
155  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
156  *    returned including, if necessary, a new dentry created with d_alloc_root.
157  *    The caller can then find any other extant dentries by following the
158  *    d_alias links.
159  *
160  * fh_to_parent:
161  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
162  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
163  *
164  * get_name:
165  *    @get_name should find a name for the given @child in the given @parent
166  *    directory.  The name should be stored in the @name (with the
167  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
168  *    buffer.   get_name() should return %0 on success, a negative error code
169  *    or error.  @get_name will be called without @parent->i_mutex held.
170  *
171  * get_parent:
172  *    @get_parent should find the parent directory for the given @child which
173  *    is also a directory.  In the event that it cannot be found, or storage
174  *    space cannot be allocated, a %ERR_PTR should be returned.
175  *
176  * commit_metadata:
177  *    @commit_metadata should commit metadata changes to stable storage.
178  *
179  * Locking rules:
180  *    get_parent is called with child->d_inode->i_mutex down
181  *    get_name is not (which is possibly inconsistent)
182  */
183 
184 /* types of block ranges for multipage write mappings. */
185 #define IOMAP_HOLE      0x01    /* no blocks allocated, need allocation */
186 #define IOMAP_DELALLOC  0x02    /* delayed allocation blocks */
187 #define IOMAP_MAPPED    0x03    /* blocks allocated @blkno */
188 #define IOMAP_UNWRITTEN 0x04    /* blocks allocated @blkno in unwritten state */
189 
190 #define IOMAP_NULL_BLOCK -1LL   /* blkno is not valid */
191 
192 struct iomap {
193         sector_t        blkno;  /* first sector of mapping */
194         loff_t          offset; /* file offset of mapping, bytes */
195         u64             length; /* length of mapping, bytes */
196         int             type;   /* type of mapping */
197 };
198 
199 struct export_operations {
200         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
201                         struct inode *parent);
202         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
203                         int fh_len, int fh_type);
204         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
205                         int fh_len, int fh_type);
206         int (*get_name)(struct dentry *parent, char *name,
207                         struct dentry *child);
208         struct dentry * (*get_parent)(struct dentry *child);
209         int (*commit_metadata)(struct inode *inode);
210 
211         int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
212         int (*map_blocks)(struct inode *inode, loff_t offset,
213                           u64 len, struct iomap *iomap,
214                           bool write, u32 *device_generation);
215         int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
216                              int nr_iomaps, struct iattr *iattr);
217 };
218 
219 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
220                                     int *max_len, struct inode *parent);
221 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
222         int *max_len, int connectable);
223 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
224         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
225         void *context);
226 
227 /*
228  * Generic helpers for filesystems.
229  */
230 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
231         struct fid *fid, int fh_len, int fh_type,
232         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
233 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
234         struct fid *fid, int fh_len, int fh_type,
235         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
236 
237 #endif /* LINUX_EXPORTFS_H */
238 

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