LXR linux/include/linux/exportfs.h

   1#ifndef LINUX_EXPORTFS_H
   2#define LINUX_EXPORTFS_H 1
   3
   4#include <linux/types.h>
   5
   6struct dentry;
   7struct inode;
   8struct super_block;
   9struct 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 */
  19enum 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
  72struct 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 * @commit_metadata: commit metadata changes to stable storage
 100 *
 101 * See Documentation/filesystems/nfs/Exporting for details on how to use
 102 * this interface correctly.
 103 *
 104 * encode_fh:
 105 *    @encode_fh should store in the file handle fragment @fh (using at most
 106 *    @max_len bytes) information that can be used by @decode_fh to recover the
 107 *    file refered to by the &struct dentry @de.  If the @connectable flag is
 108 *    set, the encode_fh() should store sufficient information so that a good
 109 *    attempt can be made to find not only the file but also it's place in the
 110 *    filesystem.   This typically means storing a reference to de->d_parent in
 111 *    the filehandle fragment.  encode_fh() should return the number of bytes
 112 *    stored or a negative error code such as %-ENOSPC
 113 *
 114 * fh_to_dentry:
 115 *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
 116 *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
 117 *    to the same file that the file handle fragment refers to.  If it cannot,
 118 *    it should return a %NULL pointer if the file was found but no acceptable
 119 *    &dentries were available, or an %ERR_PTR error code indicating why it
 120 *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
 121 *    returned including, if necessary, a new dentry created with d_alloc_root.
 122 *    The caller can then find any other extant dentries by following the
 123 *    d_alias links.
 124 *
 125 * fh_to_parent:
 126 *    Same as @fh_to_dentry, except that it returns a pointer to the parent
 127 *    dentry if it was encoded into the filehandle fragment by @encode_fh.
 128 *
 129 * get_name:
 130 *    @get_name should find a name for the given @child in the given @parent
 131 *    directory.  The name should be stored in the @name (with the
 132 *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 133 *    buffer.   get_name() should return %0 on success, a negative error code
 134 *    or error.  @get_name will be called without @parent->i_mutex held.
 135 *
 136 * get_parent:
 137 *    @get_parent should find the parent directory for the given @child which
 138 *    is also a directory.  In the event that it cannot be found, or storage
 139 *    space cannot be allocated, a %ERR_PTR should be returned.
 140 *
 141 * commit_metadata:
 142 *    @commit_metadata should commit metadata changes to stable storage.
 143 *
 144 * Locking rules:
 145 *    get_parent is called with child->d_inode->i_mutex down
 146 *    get_name is not (which is possibly inconsistent)
 147 */
 148
 149struct export_operations {
 150        int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
 151                        int connectable);
 152        struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 153                        int fh_len, int fh_type);
 154        struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 155                        int fh_len, int fh_type);
 156        int (*get_name)(struct dentry *parent, char *name,
 157                        struct dentry *child);
 158        struct dentry * (*get_parent)(struct dentry *child);
 159        int (*commit_metadata)(struct inode *inode);
 160};
 161
 162extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 163        int *max_len, int connectable);
 164extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 165        int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 166        void *context);
 167
 168/*
 169 * Generic helpers for filesystems.
 170 */
 171extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 172        struct fid *fid, int fh_len, int fh_type,
 173        struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 174extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 175        struct fid *fid, int fh_len, int fh_type,
 176        struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 177
 178#endif /* LINUX_EXPORTFS_H */
 179