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 struct fid {
  39         union {
  40                 struct {
  41                         u32 ino;
  42                         u32 gen;
  43                         u32 parent_ino;
  44                         u32 parent_gen;
  45                 } i32;
  46                 __u32 raw[6];
  47         };
  48 };
  49
  50 /**
  51  * struct export_operations - for nfsd to communicate with file systems
  52 <<<<<<< HEAD:include/linux/exportfs.h
  53  * @decode_fh:      decode a file handle fragment and return a &struct dentry
  54 =======
  55 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:include/linux/exportfs.h
  56  * @encode_fh:      encode a file handle fragment from a dentry
  57 <<<<<<< HEAD:include/linux/exportfs.h
  58 =======
  59  * @fh_to_dentry:   find the implied object and get a dentry for it
  60  * @fh_to_parent:   find the implied object's parent and get a dentry for it
  61 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:include/linux/exportfs.h
  62  * @get_name:       find the name for a given inode in a given directory
  63  * @get_parent:     find the parent of a given directory
  64 <<<<<<< HEAD:include/linux/exportfs.h
  65  * @get_dentry:     find a dentry for the inode given a file handle sub-fragment
  66 =======
  67 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:include/linux/exportfs.h
  68  *
  69  * See Documentation/filesystems/Exporting for details on how to use
  70  * this interface correctly.
  71  *
  72  * encode_fh:
  73  *    @encode_fh should store in the file handle fragment @fh (using at most
  74  *    @max_len bytes) information that can be used by @decode_fh to recover the
  75  *    file refered to by the &struct dentry @de.  If the @connectable flag is
  76  *    set, the encode_fh() should store sufficient information so that a good
  77  *    attempt can be made to find not only the file but also it's place in the
  78  *    filesystem.   This typically means storing a reference to de->d_parent in
  79  *    the filehandle fragment.  encode_fh() should return the number of bytes
  80  *    stored or a negative error code such as %-ENOSPC
  81  *
  82  * fh_to_dentry:
  83  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
  84  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
  85  *    to the same file that the file handle fragment refers to.  If it cannot,
  86  *    it should return a %NULL pointer if the file was found but no acceptable
  87  *    &dentries were available, or an %ERR_PTR error code indicating why it
  88  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
  89  *    returned including, if necessary, a new dentry created with d_alloc_root.
  90  *    The caller can then find any other extant dentries by following the
  91  *    d_alias links.
  92  *
  93  * fh_to_parent:
  94  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
  95  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
  96  *
  97  * get_name:
  98  *    @get_name should find a name for the given @child in the given @parent
  99  *    directory.  The name should be stored in the @name (with the
 100  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 101  *    buffer.   get_name() should return %0 on success, a negative error code
 102  *    or error.  @get_name will be called without @parent->i_mutex held.
 103  *
 104  * get_parent:
 105  *    @get_parent should find the parent directory for the given @child which
 106  *    is also a directory.  In the event that it cannot be found, or storage
 107  *    space cannot be allocated, a %ERR_PTR should be returned.
 108  *
 109  * Locking rules:
 110  *    get_parent is called with child->d_inode->i_mutex down
 111  *    get_name is not (which is possibly inconsistent)
 112  */
 113
 114 struct export_operations {
 115         int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
 116                         int connectable);
 117         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 118                         int fh_len, int fh_type);
 119         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 120                         int fh_len, int fh_type);
 121         int (*get_name)(struct dentry *parent, char *name,
 122                         struct dentry *child);
 123         struct dentry * (*get_parent)(struct dentry *child);
 124 };
 125
 126 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 127         int *max_len, int connectable);
 128 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 129         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 130         void *context);
 131
 132 /*
 133  * Generic helpers for filesystems.
 134  */
 135 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 136         struct fid *fid, int fh_len, int fh_type,
 137         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 138 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 139         struct fid *fid, int fh_len, int fh_type,
 140         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 141
 142 #endif /* LINUX_EXPORTFS_H */