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          * 128 bit child FID (struct lu_fid)
 101          * 128 bit parent FID (struct lu_fid)
 102          */
 103         FILEID_LUSTRE = 0x97,
 104
 105         /*
 106          * Filesystems must not use 0xff file ID.
 107          */
 108         FILEID_INVALID = 0xff,
 109 };
 110
 111 struct fid {
 112         union {
 113                 struct {
 114                         u32 ino;
 115                         u32 gen;
 116                         u32 parent_ino;
 117                         u32 parent_gen;
 118                 } i32;
 119                 struct {
 120                         u32 block;
 121                         u16 partref;
 122                         u16 parent_partref;
 123                         u32 generation;
 124                         u32 parent_block;
 125                         u32 parent_generation;
 126                 } udf;
 127                 __u32 raw[0];
 128         };
 129 };
 130
 131 /**
 132  * struct export_operations - for nfsd to communicate with file systems
 133  * @encode_fh:      encode a file handle fragment from a dentry
 134  * @fh_to_dentry:   find the implied object and get a dentry for it
 135  * @fh_to_parent:   find the implied object's parent and get a dentry for it
 136  * @get_name:       find the name for a given inode in a given directory
 137  * @get_parent:     find the parent of a given directory
 138  * @commit_metadata: commit metadata changes to stable storage
 139  *
 140  * See Documentation/filesystems/nfs/Exporting for details on how to use
 141  * this interface correctly.
 142  *
 143  * encode_fh:
 144  *    @encode_fh should store in the file handle fragment @fh (using at most
 145  *    @max_len bytes) information that can be used by @decode_fh to recover the
 146  *    file referred to by the &struct dentry @de.  If the @connectable flag is
 147  *    set, the encode_fh() should store sufficient information so that a good
 148  *    attempt can be made to find not only the file but also it's place in the
 149  *    filesystem.   This typically means storing a reference to de->d_parent in
 150  *    the filehandle fragment.  encode_fh() should return the fileid_type on
 151  *    success and on error returns 255 (if the space needed to encode fh is
 152  *    greater than @max_len*4 bytes). On error @max_len contains the minimum
 153  *    size(in 4 byte unit) needed to encode the file handle.
 154  *
 155  * fh_to_dentry:
 156  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle
 157  *    fragment (@fh, @fh_len). It should return a &struct dentry which refers
 158  *    to the same file that the file handle fragment refers to.  If it cannot,
 159  *    it should return a %NULL pointer if the file was found but no acceptable
 160  *    &dentries were available, or an %ERR_PTR error code indicating why it
 161  *    couldn't be found (e.g. %ENOENT or %ENOMEM).  Any suitable dentry can be
 162  *    returned including, if necessary, a new dentry created with d_alloc_root.
 163  *    The caller can then find any other extant dentries by following the
 164  *    d_alias links.
 165  *
 166  * fh_to_parent:
 167  *    Same as @fh_to_dentry, except that it returns a pointer to the parent
 168  *    dentry if it was encoded into the filehandle fragment by @encode_fh.
 169  *
 170  * get_name:
 171  *    @get_name should find a name for the given @child in the given @parent
 172  *    directory.  The name should be stored in the @name (with the
 173  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
 174  *    buffer.   get_name() should return %0 on success, a negative error code
 175  *    or error.  @get_name will be called without @parent->i_mutex held.
 176  *
 177  * get_parent:
 178  *    @get_parent should find the parent directory for the given @child which
 179  *    is also a directory.  In the event that it cannot be found, or storage
 180  *    space cannot be allocated, a %ERR_PTR should be returned.
 181  *
 182  * commit_metadata:
 183  *    @commit_metadata should commit metadata changes to stable storage.
 184  *
 185  * Locking rules:
 186  *    get_parent is called with child->d_inode->i_mutex down
 187  *    get_name is not (which is possibly inconsistent)
 188  */
 189
 190 /* types of block ranges for multipage write mappings. */
 191 #define IOMAP_HOLE      0x01    /* no blocks allocated, need allocation */
 192 #define IOMAP_DELALLOC  0x02    /* delayed allocation blocks */
 193 #define IOMAP_MAPPED    0x03    /* blocks allocated @blkno */
 194 #define IOMAP_UNWRITTEN 0x04    /* blocks allocated @blkno in unwritten state */
 195
 196 #define IOMAP_NULL_BLOCK -1LL   /* blkno is not valid */
 197
 198 struct iomap {
 199         sector_t        blkno;  /* first sector of mapping */
 200         loff_t          offset; /* file offset of mapping, bytes */
 201         u64             length; /* length of mapping, bytes */
 202         int             type;   /* type of mapping */
 203 };
 204
 205 struct export_operations {
 206         int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
 207                         struct inode *parent);
 208         struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
 209                         int fh_len, int fh_type);
 210         struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
 211                         int fh_len, int fh_type);
 212         int (*get_name)(struct dentry *parent, char *name,
 213                         struct dentry *child);
 214         struct dentry * (*get_parent)(struct dentry *child);
 215         int (*commit_metadata)(struct inode *inode);
 216
 217         int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
 218         int (*map_blocks)(struct inode *inode, loff_t offset,
 219                           u64 len, struct iomap *iomap,
 220                           bool write, u32 *device_generation);
 221         int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
 222                              int nr_iomaps, struct iattr *iattr);
 223 };
 224
 225 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
 226                                     int *max_len, struct inode *parent);
 227 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 228         int *max_len, int connectable);
 229 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 230         int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
 231         void *context);
 232
 233 /*
 234  * Generic helpers for filesystems.
 235  */
 236 extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
 237         struct fid *fid, int fh_len, int fh_type,
 238         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 239 extern struct dentry *generic_fh_to_parent(struct super_block *sb,
 240         struct fid *fid, int fh_len, int fh_type,
 241         struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
 242
 243 #endif /* LINUX_EXPORTFS_H */