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 super_block;
  10 struct vfsmount;
  11
  12 /* limit the handle size to NFSv4 handle size now */
  13 #define MAX_HANDLE_SZ 128
  14
  15 /*
  16  * The fileid_type identifies how the file within the filesystem is encoded.
  17  * In theory this is freely set and parsed by the filesystem, but we try to
  18  * stick to conventions so we can share some generic code and don't confuse
  19  * sniffers like ethereal/wireshark.
  20  *
  21  * The filesystem must not use the value '0' or '0xff'.
  22  */
  23 enum fid_type {
  24         /*
  25          * The root, or export point, of the filesystem.
  26          * (Never actually passed down to the filesystem.
  27          */
  28         FILEID_ROOT = 0,
  29
  30         /*
  31          * 32bit inode number, 32 bit generation number.
  32          */
  33         FILEID_INO32_GEN = 1,
  34
  35         /*
  36          * 32bit inode number, 32 bit generation number,
  37          * 32 bit parent directory inode number.
  38          */
  39         FILEID_INO32_GEN_PARENT = 2,
  40
  41         /*
  42          * 64 bit object ID, 64 bit root object ID,
  43          * 32 bit generation number.
  44          */
  45         FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
  46
  47         /*
  48          * 64 bit object ID, 64 bit root object ID,
  49          * 32 bit generation number,
  50          * 64 bit parent object ID, 32 bit parent generation.
  51          */
  52         FILEID_BTRFS_WITH_PARENT = 0x4e,
  53
  54         /*
  55          * 64 bit object ID, 64 bit root object ID,
  56          * 32 bit generation number,
  57          * 64 bit parent object ID, 32 bit parent generation,
  58          * 64 bit parent root object ID.
  59          */
  60         FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
  61
  62         /*
  63          * 32 bit block number, 16 bit partition reference,
  64          * 16 bit unused, 32 bit generation number.
  65          */
  66         FILEID_UDF_WITHOUT_PARENT = 0x51,
  67
  68         /*
  69          * 32 bit block number, 16 bit partition reference,
  70          * 16 bit unused, 32 bit generation number,
  71          * 32 bit parent block number, 32 bit parent generation number
  72          */
  73         FILEID_UDF_WITH_PARENT = 0x52,
  74
  75         /*
  76          * 64 bit checkpoint number, 64 bit inode number,
  77          * 32 bit generation number.
  78          */
  79         FILEID_NILFS_WITHOUT_PARENT = 0x61,
  80
  81         /*
  82          * 64 bit checkpoint number, 64 bit inode number,
  83          * 32 bit generation number, 32 bit parent generation.
  84          * 64 bit parent inode number.
  85          */
  86         FILEID_NILFS_WITH_PARENT = 0x62,
  87
  88         /*
  89          * 32 bit generation number, 40 bit i_pos.
  90          */
  91         FILEID_FAT_WITHOUT_PARENT = 0x71,
  92
  93         /*
  94          * 32 bit generation number, 40 bit i_pos,
  95          * 32 bit parent generation number, 40 bit parent i_pos
  96          */
  97         FILEID_FAT_WITH_PARENT = 0x72,
  98
  99         /*
 100          * Filesystems must not use 0xff file ID.
 101          */
 102         FILEID_INVALID = 0xff,
 103 };
 104
 105 struct fid {
 106         union {
 107                 struct {
 108                         u32 ino;
 109                         u32 gen;
 110                         u32 parent_ino;
 111                         u32 parent_gen;
 112                 } i32;
 113                 struct {
 114                         u32 block;
 115                         u16 partref;
 116                         u16 parent_partref;
 117                         u32 generation;
 118                         u32 parent_block;
 119                         u32 parent_generation;
 120                 } udf;
 121                 __u32 raw[0];
 122         };
 123 };
 124
 125 /**
 126  * struct export_operations - for nfsd to communicate with file systems
 127  * @encode_fh:      encode a file handle fragment from a dentry
 128  * @fh_to_dentry:   find the implied object and get a dentry for it
 129  * @fh_to_parent:   find the implied object's parent and get a dentry for it
 130  * @get_name:       find the name for a given inode in a given directory
 131  * @get_parent:     find the parent of a given directory
 132  * @commit_metadata: commit metadata changes to stable storage
 133  *
 134  * See Documentation/filesystems/nfs/Exporting for details on how to use
 135  * this interface correctly.
 136  *
 137  * encode_fh:
 138  *    @encode_fh should store in the file handle fragment @fh (using at most
 139  *    @max_len bytes) information that can be used by @decode_fh to recover the
 140  *    file referred to by the &struct dentry @de.  If the @connectable flag is
 141  *    set, the encode_fh() should store sufficient information so that a good
 142  *    attempt can be made to find not only the file but also it's place in the
 143  *    filesystem.   This typically means storing a reference to de->d_parent in
 144  *    the filehandle fragment.  encode_fh() should return the fileid_type on
 145  *    success and on error returns 255 (if the space needed to encode fh is
 146  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
 147  *    size(in 4 byte unit) needed to encode the file handle.
 148  *
 149  * fh_to_dentry:
 150  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
 151  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
 152  *    to the same file that the file handle fragment refers to.  If it cannot,
 153  *    it should return a %NULL pointer if the file was found but no acceptable
 154  *    &dentries were available, or an %ERR_PTR error code indicating why it
 155  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
 156  *    returned including, if necessary, a new dentry created with d_alloc_root.
 157  *    The caller can then find any other extant dentries by following the
 158  *    d_alias links.
 159  *
 160  * fh_to_parent:
 161  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
 162  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
 163  *
 164  * get_name:
 165  *    @get_name should find a name for the given @child in the given @parent
 166  *    directory.  The name should be stored in the @name (with the
 167  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 168  *    buffer.   get_name() should return %0 on success, a negative error code
 169  *    or error.  @get_name will be called without @parent->i_mutex held.
 170  *
 171  * get_parent:
 172  *    @get_parent should find the parent directory for the given @child which
 173  *    is also a directory.  In the event that it cannot be found, or storage
 174  *    space cannot be allocated, a %ERR_PTR should be returned.
 175  *
 176  * commit_metadata:
 177  *    @commit_metadata should commit metadata changes to stable storage.
 178  *
 179  * Locking rules:
 180  *    get_parent is called with child->d_inode->i_mutex down
 181  *    get_name is not (which is possibly inconsistent)
 182  */
 183
 184 /* types of block ranges for multipage write mappings. */
 185 #define IOMAP_HOLE      0x01    /* no blocks allocated, need allocation */
 186 #define IOMAP_DELALLOC  0x02    /* delayed allocation blocks */
 187 #define IOMAP_MAPPED    0x03    /* blocks allocated @blkno */
 188 #define IOMAP_UNWRITTEN 0x04    /* blocks allocated @blkno in unwritten state */
 189
 190 #define IOMAP_NULL_BLOCK -1LL   /* blkno is not valid */
 191
 192 struct iomap {
 193         sector_t        blkno;  /* first sector of mapping */
 194         loff_t          offset; /* file offset of mapping, bytes */
 195         u64             length; /* length of mapping, bytes */
 196         int             type;   /* type of mapping */
 197 };
 198
 199 struct export_operations {
 200         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
 201                         struct inode *parent);
 202         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 203                         int fh_len, int fh_type);
 204         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 205                         int fh_len, int fh_type);
 206         int (*get_name)(struct dentry *parent, char *name,
 207                         struct dentry *child);
 208         struct dentry * (*get_parent)(struct dentry *child);
 209         int (*commit_metadata)(struct inode *inode);
 210
 211         int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
 212         int (*map_blocks)(struct inode *inode, loff_t offset,
 213                           u64 len, struct iomap *iomap,
 214                           bool write, u32 *device_generation);
 215         int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
 216                              int nr_iomaps, struct iattr *iattr);
 217 };
 218
 219 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
 220                                     int *max_len, struct inode *parent);
 221 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 222         int *max_len, int connectable);
 223 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 224         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 225         void *context);
 226
 227 /*
 228  * Generic helpers for filesystems.
 229  */
 230 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 231         struct fid *fid, int fh_len, int fh_type,
 232         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 233 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 234         struct fid *fid, int fh_len, int fh_type,
 235         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 236
 237 #endif /* LINUX_EXPORTFS_H */