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 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 '0' 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 struct fid {
  89         union {
  90                 struct {
  91                         u32 ino;
  92                         u32 gen;
  93                         u32 parent_ino;
  94                         u32 parent_gen;
  95                 } i32;
  96                 struct {
  97                         u32 block;
  98                         u16 partref;
  99                         u16 parent_partref;
 100                         u32 generation;
 101                         u32 parent_block;
 102                         u32 parent_generation;
 103                 } udf;
 104                 __u32 raw[0];
 105         };
 106 };
 107
 108 /**
 109  * struct export_operations - for nfsd to communicate with file systems
 110  * @encode_fh:      encode a file handle fragment from a dentry
 111  * @fh_to_dentry:   find the implied object and get a dentry for it
 112  * @fh_to_parent:   find the implied object's parent and get a dentry for it
 113  * @get_name:       find the name for a given inode in a given directory
 114  * @get_parent:     find the parent of a given directory
 115  * @commit_metadata: commit metadata changes to stable storage
 116  *
 117  * See Documentation/filesystems/nfs/Exporting for details on how to use
 118  * this interface correctly.
 119  *
 120  * encode_fh:
 121  *    @encode_fh should store in the file handle fragment @fh (using at most
 122  *    @max_len bytes) information that can be used by @decode_fh to recover the
 123  *    file referred to by the &struct dentry @de.  If the @connectable flag is
 124  *    set, the encode_fh() should store sufficient information so that a good
 125  *    attempt can be made to find not only the file but also it's place in the
 126  *    filesystem.   This typically means storing a reference to de->d_parent in
 127  *    the filehandle fragment.  encode_fh() should return the fileid_type on
 128  *    success and on error returns 255 (if the space needed to encode fh is
 129  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
 130  *    size(in 4 byte unit) needed to encode the file handle.
 131  *
 132  * fh_to_dentry:
 133  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
 134  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
 135  *    to the same file that the file handle fragment refers to.  If it cannot,
 136  *    it should return a %NULL pointer if the file was found but no acceptable
 137  *    &dentries were available, or an %ERR_PTR error code indicating why it
 138  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
 139  *    returned including, if necessary, a new dentry created with d_alloc_root.
 140  *    The caller can then find any other extant dentries by following the
 141  *    d_alias links.
 142  *
 143  * fh_to_parent:
 144  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
 145  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
 146  *
 147  * get_name:
 148  *    @get_name should find a name for the given @child in the given @parent
 149  *    directory.  The name should be stored in the @name (with the
 150  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 151  *    buffer.   get_name() should return %0 on success, a negative error code
 152  *    or error.  @get_name will be called without @parent->i_mutex held.
 153  *
 154  * get_parent:
 155  *    @get_parent should find the parent directory for the given @child which
 156  *    is also a directory.  In the event that it cannot be found, or storage
 157  *    space cannot be allocated, a %ERR_PTR should be returned.
 158  *
 159  * commit_metadata:
 160  *    @commit_metadata should commit metadata changes to stable storage.
 161  *
 162  * Locking rules:
 163  *    get_parent is called with child->d_inode->i_mutex down
 164  *    get_name is not (which is possibly inconsistent)
 165  */
 166
 167 struct export_operations {
 168         int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
 169                         int connectable);
 170         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 171                         int fh_len, int fh_type);
 172         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 173                         int fh_len, int fh_type);
 174         int (*get_name)(struct dentry *parent, char *name,
 175                         struct dentry *child);
 176         struct dentry * (*get_parent)(struct dentry *child);
 177         int (*commit_metadata)(struct inode *inode);
 178 };
 179
 180 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 181         int *max_len, int connectable);
 182 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 183         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 184         void *context);
 185
 186 /*
 187  * Generic helpers for filesystems.
 188  */
 189 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 190         struct fid *fid, int fh_len, int fh_type,
 191         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 192 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 193         struct fid *fid, int fh_len, int fh_type,
 194         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 195
 196 #endif /* LINUX_EXPORTFS_H */