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

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 #ifndef LINUX_EXPORTFS_H
  3 #define LINUX_EXPORTFS_H 1
  4 
  5 #include <linux/types.h>
  6 
  7 struct dentry;
  8 struct iattr;
  9 struct inode;
 10 struct iomap;
 11 struct super_block;
 12 struct vfsmount;
 13 
 14 /* limit the handle size to NFSv4 handle size now */
 15 #define MAX_HANDLE_SZ 128
 16 
 17 /*
 18  * The fileid_type identifies how the file within the filesystem is encoded.
 19  * In theory this is freely set and parsed by the filesystem, but we try to
 20  * stick to conventions so we can share some generic code and don't confuse
 21  * sniffers like ethereal/wireshark.
 22  *
 23  * The filesystem must not use the value '' or '0xff'.
 24  */
 25 enum fid_type {
 26         /*
 27          * The root, or export point, of the filesystem.
 28          * (Never actually passed down to the filesystem.
 29          */
 30         FILEID_ROOT = 0,
 31 
 32         /*
 33          * 32bit inode number, 32 bit generation number.
 34          */
 35         FILEID_INO32_GEN = 1,
 36 
 37         /*
 38          * 32bit inode number, 32 bit generation number,
 39          * 32 bit parent directory inode number.
 40          */
 41         FILEID_INO32_GEN_PARENT = 2,
 42 
 43         /*
 44          * 64 bit object ID, 64 bit root object ID,
 45          * 32 bit generation number.
 46          */
 47         FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
 48 
 49         /*
 50          * 64 bit object ID, 64 bit root object ID,
 51          * 32 bit generation number,
 52          * 64 bit parent object ID, 32 bit parent generation.
 53          */
 54         FILEID_BTRFS_WITH_PARENT = 0x4e,
 55 
 56         /*
 57          * 64 bit object ID, 64 bit root object ID,
 58          * 32 bit generation number,
 59          * 64 bit parent object ID, 32 bit parent generation,
 60          * 64 bit parent root object ID.
 61          */
 62         FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
 63 
 64         /*
 65          * 32 bit block number, 16 bit partition reference,
 66          * 16 bit unused, 32 bit generation number.
 67          */
 68         FILEID_UDF_WITHOUT_PARENT = 0x51,
 69 
 70         /*
 71          * 32 bit block number, 16 bit partition reference,
 72          * 16 bit unused, 32 bit generation number,
 73          * 32 bit parent block number, 32 bit parent generation number
 74          */
 75         FILEID_UDF_WITH_PARENT = 0x52,
 76 
 77         /*
 78          * 64 bit checkpoint number, 64 bit inode number,
 79          * 32 bit generation number.
 80          */
 81         FILEID_NILFS_WITHOUT_PARENT = 0x61,
 82 
 83         /*
 84          * 64 bit checkpoint number, 64 bit inode number,
 85          * 32 bit generation number, 32 bit parent generation.
 86          * 64 bit parent inode number.
 87          */
 88         FILEID_NILFS_WITH_PARENT = 0x62,
 89 
 90         /*
 91          * 32 bit generation number, 40 bit i_pos.
 92          */
 93         FILEID_FAT_WITHOUT_PARENT = 0x71,
 94 
 95         /*
 96          * 32 bit generation number, 40 bit i_pos,
 97          * 32 bit parent generation number, 40 bit parent i_pos
 98          */
 99         FILEID_FAT_WITH_PARENT = 0x72,
100 
101         /*
102          * 128 bit child FID (struct lu_fid)
103          * 128 bit parent FID (struct lu_fid)
104          */
105         FILEID_LUSTRE = 0x97,
106 
107         /*
108          * 64 bit unique kernfs id
109          */
110         FILEID_KERNFS = 0xfe,
111 
112         /*
113          * Filesystems must not use 0xff file ID.
114          */
115         FILEID_INVALID = 0xff,
116 };
117 
118 struct fid {
119         union {
120                 struct {
121                         u32 ino;
122                         u32 gen;
123                         u32 parent_ino;
124                         u32 parent_gen;
125                 } i32;
126                 struct {
127                         u32 block;
128                         u16 partref;
129                         u16 parent_partref;
130                         u32 generation;
131                         u32 parent_block;
132                         u32 parent_generation;
133                 } udf;
134                 __u32 raw[0];
135         };
136 };
137 
138 /**
139  * struct export_operations - for nfsd to communicate with file systems
140  * @encode_fh:      encode a file handle fragment from a dentry
141  * @fh_to_dentry:   find the implied object and get a dentry for it
142  * @fh_to_parent:   find the implied object's parent and get a dentry for it
143  * @get_name:       find the name for a given inode in a given directory
144  * @get_parent:     find the parent of a given directory
145  * @commit_metadata: commit metadata changes to stable storage
146  *
147  * See Documentation/filesystems/nfs/exporting.rst for details on how to use
148  * this interface correctly.
149  *
150  * encode_fh:
151  *    @encode_fh should store in the file handle fragment @fh (using at most
152  *    @max_len bytes) information that can be used by @decode_fh to recover the
153  *    file referred to by the &struct dentry @de.  If the @connectable flag is
154  *    set, the encode_fh() should store sufficient information so that a good
155  *    attempt can be made to find not only the file but also it's place in the
156  *    filesystem.   This typically means storing a reference to de->d_parent in
157  *    the filehandle fragment.  encode_fh() should return the fileid_type on
158  *    success and on error returns 255 (if the space needed to encode fh is
159  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
160  *    size(in 4 byte unit) needed to encode the file handle.
161  *
162  * fh_to_dentry:
163  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
164  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
165  *    to the same file that the file handle fragment refers to.  If it cannot,
166  *    it should return a %NULL pointer if the file cannot be found, or an
167  *    %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
168  *    Any other error code is treated like %NULL, and will cause an %ESTALE error
169  *    for callers of exportfs_decode_fh().
170  *    Any suitable dentry can be returned including, if necessary, a new dentry
171  *    created with d_alloc_root.  The caller can then find any other extant
172  *    dentries by following the d_alias links.
173  *
174  * fh_to_parent:
175  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
176  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
177  *
178  * get_name:
179  *    @get_name should find a name for the given @child in the given @parent
180  *    directory.  The name should be stored in the @name (with the
181  *    understanding that it is already pointing to a %NAME_MAX+1 sized
182  *    buffer.   get_name() should return %0 on success, a negative error code
183  *    or error.  @get_name will be called without @parent->i_mutex held.
184  *
185  * get_parent:
186  *    @get_parent should find the parent directory for the given @child which
187  *    is also a directory.  In the event that it cannot be found, or storage
188  *    space cannot be allocated, a %ERR_PTR should be returned.
189  *
190  * commit_metadata:
191  *    @commit_metadata should commit metadata changes to stable storage.
192  *
193  * Locking rules:
194  *    get_parent is called with child->d_inode->i_mutex down
195  *    get_name is not (which is possibly inconsistent)
196  */
197 
198 struct export_operations {
199         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
200                         struct inode *parent);
201         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
202                         int fh_len, int fh_type);
203         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
204                         int fh_len, int fh_type);
205         int (*get_name)(struct dentry *parent, char *name,
206                         struct dentry *child);
207         struct dentry * (*get_parent)(struct dentry *child);
208         int (*commit_metadata)(struct inode *inode);
209 
210         int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
211         int (*map_blocks)(struct inode *inode, loff_t offset,
212                           u64 len, struct iomap *iomap,
213                           bool write, u32 *device_generation);
214         int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
215                              int nr_iomaps, struct iattr *iattr);
216         u64 (*fetch_iversion)(struct inode *);
217 #define EXPORT_OP_NOWCC                 (0x1) /* don't collect v3 wcc data */
218 #define EXPORT_OP_NOSUBTREECHK          (0x2) /* no subtree checking */
219 #define EXPORT_OP_CLOSE_BEFORE_UNLINK   (0x4) /* close files before unlink */
220 #define EXPORT_OP_REMOTE_FS             (0x8) /* Filesystem is remote */
221 #define EXPORT_OP_NOATOMIC_ATTR         (0x10) /* Filesystem cannot supply
222                                                   atomic attribute updates
223                                                 */
224 #define EXPORT_OP_SYNC_LOCKS            (0x20) /* Filesystem can't do
225                                                   asychronous blocking locks */
226         unsigned long   flags;
227 };
228 
229 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
230                                     int *max_len, struct inode *parent);
231 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
232         int *max_len, int connectable);
233 extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt,
234                                              struct fid *fid, int fh_len,
235                                              int fileid_type,
236                                              int (*acceptable)(void *, struct dentry *),
237                                              void *context);
238 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
239         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
240         void *context);
241 
242 /*
243  * Generic helpers for filesystems.
244  */
245 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
246         struct fid *fid, int fh_len, int fh_type,
247         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
248 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
249         struct fid *fid, int fh_len, int fh_type,
250         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
251 
252 #endif /* LINUX_EXPORTFS_H */
253 

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