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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          * 128 bit child FID (struct lu_fid)
101          * 128 bit parent FID (struct lu_fid)
102          */
103         FILEID_LUSTRE = 0x97,
104 
105         /*
106          * Filesystems must not use 0xff file ID.
107          */
108         FILEID_INVALID = 0xff,
109 };
110 
111 struct fid {
112         union {
113                 struct {
114                         u32 ino;
115                         u32 gen;
116                         u32 parent_ino;
117                         u32 parent_gen;
118                 } i32;
119                 struct {
120                         u32 block;
121                         u16 partref;
122                         u16 parent_partref;
123                         u32 generation;
124                         u32 parent_block;
125                         u32 parent_generation;
126                 } udf;
127                 __u32 raw[0];
128         };
129 };
130 
131 /**
132  * struct export_operations - for nfsd to communicate with file systems
133  * @encode_fh:      encode a file handle fragment from a dentry
134  * @fh_to_dentry:   find the implied object and get a dentry for it
135  * @fh_to_parent:   find the implied object's parent and get a dentry for it
136  * @get_name:       find the name for a given inode in a given directory
137  * @get_parent:     find the parent of a given directory
138  * @commit_metadata: commit metadata changes to stable storage
139  *
140  * See Documentation/filesystems/nfs/Exporting for details on how to use
141  * this interface correctly.
142  *
143  * encode_fh:
144  *    @encode_fh should store in the file handle fragment @fh (using at most
145  *    @max_len bytes) information that can be used by @decode_fh to recover the
146  *    file referred to by the &struct dentry @de.  If the @connectable flag is
147  *    set, the encode_fh() should store sufficient information so that a good
148  *    attempt can be made to find not only the file but also it's place in the
149  *    filesystem.   This typically means storing a reference to de->d_parent in
150  *    the filehandle fragment.  encode_fh() should return the fileid_type on
151  *    success and on error returns 255 (if the space needed to encode fh is
152  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
153  *    size(in 4 byte unit) needed to encode the file handle.
154  *
155  * fh_to_dentry:
156  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
157  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
158  *    to the same file that the file handle fragment refers to.  If it cannot,
159  *    it should return a %NULL pointer if the file was found but no acceptable
160  *    &dentries were available, or an %ERR_PTR error code indicating why it
161  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
162  *    returned including, if necessary, a new dentry created with d_alloc_root.
163  *    The caller can then find any other extant dentries by following the
164  *    d_alias links.
165  *
166  * fh_to_parent:
167  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
168  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
169  *
170  * get_name:
171  *    @get_name should find a name for the given @child in the given @parent
172  *    directory.  The name should be stored in the @name (with the
173  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
174  *    buffer.   get_name() should return %0 on success, a negative error code
175  *    or error.  @get_name will be called without @parent->i_mutex held.
176  *
177  * get_parent:
178  *    @get_parent should find the parent directory for the given @child which
179  *    is also a directory.  In the event that it cannot be found, or storage
180  *    space cannot be allocated, a %ERR_PTR should be returned.
181  *
182  * commit_metadata:
183  *    @commit_metadata should commit metadata changes to stable storage.
184  *
185  * Locking rules:
186  *    get_parent is called with child->d_inode->i_mutex down
187  *    get_name is not (which is possibly inconsistent)
188  */
189 
190 /* types of block ranges for multipage write mappings. */
191 #define IOMAP_HOLE      0x01    /* no blocks allocated, need allocation */
192 #define IOMAP_DELALLOC  0x02    /* delayed allocation blocks */
193 #define IOMAP_MAPPED    0x03    /* blocks allocated @blkno */
194 #define IOMAP_UNWRITTEN 0x04    /* blocks allocated @blkno in unwritten state */
195 
196 #define IOMAP_NULL_BLOCK -1LL   /* blkno is not valid */
197 
198 struct iomap {
199         sector_t        blkno;  /* first sector of mapping */
200         loff_t          offset; /* file offset of mapping, bytes */
201         u64             length; /* length of mapping, bytes */
202         int             type;   /* type of mapping */
203 };
204 
205 struct export_operations {
206         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
207                         struct inode *parent);
208         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
209                         int fh_len, int fh_type);
210         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
211                         int fh_len, int fh_type);
212         int (*get_name)(struct dentry *parent, char *name,
213                         struct dentry *child);
214         struct dentry * (*get_parent)(struct dentry *child);
215         int (*commit_metadata)(struct inode *inode);
216 
217         int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
218         int (*map_blocks)(struct inode *inode, loff_t offset,
219                           u64 len, struct iomap *iomap,
220                           bool write, u32 *device_generation);
221         int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
222                              int nr_iomaps, struct iattr *iattr);
223 };
224 
225 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
226                                     int *max_len, struct inode *parent);
227 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
228         int *max_len, int connectable);
229 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
230         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
231         void *context);
232 
233 /*
234  * Generic helpers for filesystems.
235  */
236 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
237         struct fid *fid, int fh_len, int fh_type,
238         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
239 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
240         struct fid *fid, int fh_len, int fh_type,
241         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
242 
243 #endif /* LINUX_EXPORTFS_H */
244 

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