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 /*
  12  * The fileid_type identifies how the file within the filesystem is encoded.
  13  * In theory this is freely set and parsed by the filesystem, but we try to
  14  * stick to conventions so we can share some generic code and don't confuse
  15  * sniffers like ethereal/wireshark.
  16  *
  17  * The filesystem must not use the value '0' or '0xff'.
  18  */
  19 enum fid_type {
  20         /*
  21          * The root, or export point, of the filesystem.
  22          * (Never actually passed down to the filesystem.
  23          */
  24         FILEID_ROOT = 0,
  25
  26         /*
  27          * 32bit inode number, 32 bit generation number.
  28          */
  29         FILEID_INO32_GEN = 1,
  30
  31         /*
  32          * 32bit inode number, 32 bit generation number,
  33          * 32 bit parent directory inode number.
  34          */
  35         FILEID_INO32_GEN_PARENT = 2,
  36
  37         /*
  38          * 64 bit object ID, 64 bit root object ID,
  39          * 32 bit generation number.
  40          */
  41         FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
  42
  43         /*
  44          * 64 bit object ID, 64 bit root object ID,
  45          * 32 bit generation number,
  46          * 64 bit parent object ID, 32 bit parent generation.
  47          */
  48         FILEID_BTRFS_WITH_PARENT = 0x4e,
  49
  50         /*
  51          * 64 bit object ID, 64 bit root object ID,
  52          * 32 bit generation number,
  53          * 64 bit parent object ID, 32 bit parent generation,
  54          * 64 bit parent root object ID.
  55          */
  56         FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
  57
  58         /*
  59          * 32 bit block number, 16 bit partition reference,
  60          * 16 bit unused, 32 bit generation number.
  61          */
  62         FILEID_UDF_WITHOUT_PARENT = 0x51,
  63
  64         /*
  65          * 32 bit block number, 16 bit partition reference,
  66          * 16 bit unused, 32 bit generation number,
  67          * 32 bit parent block number, 32 bit parent generation number
  68          */
  69         FILEID_UDF_WITH_PARENT = 0x52,
  70 };
  71
  72 struct fid {
  73         union {
  74                 struct {
  75                         u32 ino;
  76                         u32 gen;
  77                         u32 parent_ino;
  78                         u32 parent_gen;
  79                 } i32;
  80                 struct {
  81                         u32 block;
  82                         u16 partref;
  83                         u16 parent_partref;
  84                         u32 generation;
  85                         u32 parent_block;
  86                         u32 parent_generation;
  87                 } udf;
  88                 __u32 raw[0];
  89         };
  90 };
  91
  92 /**
  93  * struct export_operations - for nfsd to communicate with file systems
  94  * @encode_fh:      encode a file handle fragment from a dentry
  95  * @fh_to_dentry:   find the implied object and get a dentry for it
  96  * @fh_to_parent:   find the implied object's parent and get a dentry for it
  97  * @get_name:       find the name for a given inode in a given directory
  98  * @get_parent:     find the parent of a given directory
  99  *
 100  * See Documentation/filesystems/nfs/Exporting for details on how to use
 101  * this interface correctly.
 102  *
 103  * encode_fh:
 104  *    @encode_fh should store in the file handle fragment @fh (using at most
 105  *    @max_len bytes) information that can be used by @decode_fh to recover the
 106  *    file refered to by the &struct dentry @de.  If the @connectable flag is
 107  *    set, the encode_fh() should store sufficient information so that a good
 108  *    attempt can be made to find not only the file but also it's place in the
 109  *    filesystem.   This typically means storing a reference to de->d_parent in
 110  *    the filehandle fragment.  encode_fh() should return the number of bytes
 111  *    stored or a negative error code such as %-ENOSPC
 112  *
 113  * fh_to_dentry:
 114  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
 115  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
 116  *    to the same file that the file handle fragment refers to.  If it cannot,
 117  *    it should return a %NULL pointer if the file was found but no acceptable
 118  *    &dentries were available, or an %ERR_PTR error code indicating why it
 119  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
 120  *    returned including, if necessary, a new dentry created with d_alloc_root.
 121  *    The caller can then find any other extant dentries by following the
 122  *    d_alias links.
 123  *
 124  * fh_to_parent:
 125  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
 126  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
 127  *
 128  * get_name:
 129  *    @get_name should find a name for the given @child in the given @parent
 130  *    directory.  The name should be stored in the @name (with the
 131  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 132  *    buffer.   get_name() should return %0 on success, a negative error code
 133  *    or error.  @get_name will be called without @parent->i_mutex held.
 134  *
 135  * get_parent:
 136  *    @get_parent should find the parent directory for the given @child which
 137  *    is also a directory.  In the event that it cannot be found, or storage
 138  *    space cannot be allocated, a %ERR_PTR should be returned.
 139  *
 140  * Locking rules:
 141  *    get_parent is called with child->d_inode->i_mutex down
 142  *    get_name is not (which is possibly inconsistent)
 143  */
 144
 145 struct export_operations {
 146         int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
 147                         int connectable);
 148         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 149                         int fh_len, int fh_type);
 150         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 151                         int fh_len, int fh_type);
 152         int (*get_name)(struct dentry *parent, char *name,
 153                         struct dentry *child);
 154         struct dentry * (*get_parent)(struct dentry *child);
 155 };
 156
 157 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 158         int *max_len, int connectable);
 159 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 160         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 161         void *context);
 162
 163 /*
 164  * Generic helpers for filesystems.
 165  */
 166 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 167         struct fid *fid, int fh_len, int fh_type,
 168         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 169 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 170         struct fid *fid, int fh_len, int fh_type,
 171         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 172
 173 #endif /* LINUX_EXPORTFS_H */