include/linux/exportfs.h

   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 iomap;
  10 struct super_block;
  11 struct vfsmount;
  12
  13 /* limit the handle size to NFSv4 handle size now */
  14 #define MAX_HANDLE_SZ 128
  15
  16 /*
  17  * The fileid_type identifies how the file within the filesystem is encoded.
  18  * In theory this is freely set and parsed by the filesystem, but we try to
  19  * stick to conventions so we can share some generic code and don't confuse
  20  * sniffers like ethereal/wireshark.
  21  *
  22  * The filesystem must not use the value '0' or '0xff'.
  23  */
  24 enum fid_type {
  25         /*
  26          * The root, or export point, of the filesystem.
  27          * (Never actually passed down to the filesystem.
  28          */
  29         FILEID_ROOT = 0,
  30
  31         /*
  32          * 32bit inode number, 32 bit generation number.
  33          */
  34         FILEID_INO32_GEN = 1,
  35
  36         /*
  37          * 32bit inode number, 32 bit generation number,
  38          * 32 bit parent directory inode number.
  39          */
  40         FILEID_INO32_GEN_PARENT = 2,
  41
  42         /*
  43          * 64 bit object ID, 64 bit root object ID,
  44          * 32 bit generation number.
  45          */
  46         FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
  47
  48         /*
  49          * 64 bit object ID, 64 bit root object ID,
  50          * 32 bit generation number,
  51          * 64 bit parent object ID, 32 bit parent generation.
  52          */
  53         FILEID_BTRFS_WITH_PARENT = 0x4e,
  54
  55         /*
  56          * 64 bit object ID, 64 bit root object ID,
  57          * 32 bit generation number,
  58          * 64 bit parent object ID, 32 bit parent generation,
  59          * 64 bit parent root object ID.
  60          */
  61         FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
  62
  63         /*
  64          * 32 bit block number, 16 bit partition reference,
  65          * 16 bit unused, 32 bit generation number.
  66          */
  67         FILEID_UDF_WITHOUT_PARENT = 0x51,
  68
  69         /*
  70          * 32 bit block number, 16 bit partition reference,
  71          * 16 bit unused, 32 bit generation number,
  72          * 32 bit parent block number, 32 bit parent generation number
  73          */
  74         FILEID_UDF_WITH_PARENT = 0x52,
  75
  76         /*
  77          * 64 bit checkpoint number, 64 bit inode number,
  78          * 32 bit generation number.
  79          */
  80         FILEID_NILFS_WITHOUT_PARENT = 0x61,
  81
  82         /*
  83          * 64 bit checkpoint number, 64 bit inode number,
  84          * 32 bit generation number, 32 bit parent generation.
  85          * 64 bit parent inode number.
  86          */
  87         FILEID_NILFS_WITH_PARENT = 0x62,
  88
  89         /*
  90          * 32 bit generation number, 40 bit i_pos.
  91          */
  92         FILEID_FAT_WITHOUT_PARENT = 0x71,
  93
  94         /*
  95          * 32 bit generation number, 40 bit i_pos,
  96          * 32 bit parent generation number, 40 bit parent i_pos
  97          */
  98         FILEID_FAT_WITH_PARENT = 0x72,
  99
 100         /*
 101          * 128 bit child FID (struct lu_fid)
 102          * 128 bit parent FID (struct lu_fid)
 103          */
 104         FILEID_LUSTRE = 0x97,
 105
 106         /*
 107          * Filesystems must not use 0xff file ID.
 108          */
 109         FILEID_INVALID = 0xff,
 110 };
 111
 112 struct fid {
 113         union {
 114                 struct {
 115                         u32 ino;
 116                         u32 gen;
 117                         u32 parent_ino;
 118                         u32 parent_gen;
 119                 } i32;
 120                 struct {
 121                         u32 block;
 122                         u16 partref;
 123                         u16 parent_partref;
 124                         u32 generation;
 125                         u32 parent_block;
 126                         u32 parent_generation;
 127                 } udf;
 128                 __u32 raw[0];
 129         };
 130 };
 131
 132 /**
 133  * struct export_operations - for nfsd to communicate with file systems
 134  * @encode_fh:      encode a file handle fragment from a dentry
 135  * @fh_to_dentry:   find the implied object and get a dentry for it
 136  * @fh_to_parent:   find the implied object's parent and get a dentry for it
 137  * @get_name:       find the name for a given inode in a given directory
 138  * @get_parent:     find the parent of a given directory
 139  * @commit_metadata: commit metadata changes to stable storage
 140  *
 141  * See Documentation/filesystems/nfs/Exporting for details on how to use
 142  * this interface correctly.
 143  *
 144  * encode_fh:
 145  *    @encode_fh should store in the file handle fragment @fh (using at most
 146  *    @max_len bytes) information that can be used by @decode_fh to recover the
 147  *    file referred to by the &struct dentry @de.  If the @connectable flag is
 148  *    set, the encode_fh() should store sufficient information so that a good
 149  *    attempt can be made to find not only the file but also it's place in the
 150  *    filesystem.   This typically means storing a reference to de->d_parent in
 151  *    the filehandle fragment.  encode_fh() should return the fileid_type on
 152  *    success and on error returns 255 (if the space needed to encode fh is
 153  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
 154  *    size(in 4 byte unit) needed to encode the file handle.
 155  *
 156  * fh_to_dentry:
 157  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
 158  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
 159  *    to the same file that the file handle fragment refers to.  If it cannot,
 160  *    it should return a %NULL pointer if the file cannot be found, or an
 161  *    %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
 162  *    Any other error code is treated like %NULL, and will cause an %ESTALE error
 163  *    for callers of exportfs_decode_fh().
 164  *    Any suitable dentry can be returned including, if necessary, a new dentry
 165  *    created with d_alloc_root.  The caller can then find any other extant
 166  *    dentries by following the d_alias links.
 167  *
 168  * fh_to_parent:
 169  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
 170  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
 171  *
 172  * get_name:
 173  *    @get_name should find a name for the given @child in the given @parent
 174  *    directory.  The name should be stored in the @name (with the
 175  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 176  *    buffer.   get_name() should return %0 on success, a negative error code
 177  *    or error.  @get_name will be called without @parent->i_mutex held.
 178  *
 179  * get_parent:
 180  *    @get_parent should find the parent directory for the given @child which
 181  *    is also a directory.  In the event that it cannot be found, or storage
 182  *    space cannot be allocated, a %ERR_PTR should be returned.
 183  *
 184  * commit_metadata:
 185  *    @commit_metadata should commit metadata changes to stable storage.
 186  *
 187  * Locking rules:
 188  *    get_parent is called with child->d_inode->i_mutex down
 189  *    get_name is not (which is possibly inconsistent)
 190  */
 191
 192 struct export_operations {
 193         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
 194                         struct inode *parent);
 195         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 196                         int fh_len, int fh_type);
 197         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 198                         int fh_len, int fh_type);
 199         int (*get_name)(struct dentry *parent, char *name,
 200                         struct dentry *child);
 201         struct dentry * (*get_parent)(struct dentry *child);
 202         int (*commit_metadata)(struct inode *inode);
 203
 204         int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
 205         int (*map_blocks)(struct inode *inode, loff_t offset,
 206                           u64 len, struct iomap *iomap,
 207                           bool write, u32 *device_generation);
 208         int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
 209                              int nr_iomaps, struct iattr *iattr);
 210 };
 211
 212 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
 213                                     int *max_len, struct inode *parent);
 214 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 215         int *max_len, int connectable);
 216 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 217         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 218         void *context);
 219
 220 /*
 221  * Generic helpers for filesystems.
 222  */
 223 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 224         struct fid *fid, int fh_len, int fh_type,
 225         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 226 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 227         struct fid *fid, int fh_len, int fh_type,
 228         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 229
 230 #endif /* LINUX_EXPORTFS_H */