exportfs.h 7.5 KB

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  1. /* SPDX-License-Identifier: GPL-2.0 */
  2. #ifndef LINUX_EXPORTFS_H
  3. #define LINUX_EXPORTFS_H 1
  4. #include <linux/types.h>
  5. struct dentry;
  6. struct iattr;
  7. struct inode;
  8. struct iomap;
  9. struct super_block;
  10. struct vfsmount;
  11. /* limit the handle size to NFSv4 handle size now */
  12. #define MAX_HANDLE_SZ 128
  13. /*
  14. * The fileid_type identifies how the file within the filesystem is encoded.
  15. * In theory this is freely set and parsed by the filesystem, but we try to
  16. * stick to conventions so we can share some generic code and don't confuse
  17. * sniffers like ethereal/wireshark.
  18. *
  19. * The filesystem must not use the value '0' or '0xff'.
  20. */
  21. enum fid_type {
  22. /*
  23. * The root, or export point, of the filesystem.
  24. * (Never actually passed down to the filesystem.
  25. */
  26. FILEID_ROOT = 0,
  27. /*
  28. * 32bit inode number, 32 bit generation number.
  29. */
  30. FILEID_INO32_GEN = 1,
  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. * 64 bit object ID, 64 bit root object ID,
  38. * 32 bit generation number.
  39. */
  40. FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
  41. /*
  42. * 64 bit object ID, 64 bit root object ID,
  43. * 32 bit generation number,
  44. * 64 bit parent object ID, 32 bit parent generation.
  45. */
  46. FILEID_BTRFS_WITH_PARENT = 0x4e,
  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. * 64 bit parent root object ID.
  52. */
  53. FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
  54. /*
  55. * 32 bit block number, 16 bit partition reference,
  56. * 16 bit unused, 32 bit generation number.
  57. */
  58. FILEID_UDF_WITHOUT_PARENT = 0x51,
  59. /*
  60. * 32 bit block number, 16 bit partition reference,
  61. * 16 bit unused, 32 bit generation number,
  62. * 32 bit parent block number, 32 bit parent generation number
  63. */
  64. FILEID_UDF_WITH_PARENT = 0x52,
  65. /*
  66. * 64 bit checkpoint number, 64 bit inode number,
  67. * 32 bit generation number.
  68. */
  69. FILEID_NILFS_WITHOUT_PARENT = 0x61,
  70. /*
  71. * 64 bit checkpoint number, 64 bit inode number,
  72. * 32 bit generation number, 32 bit parent generation.
  73. * 64 bit parent inode number.
  74. */
  75. FILEID_NILFS_WITH_PARENT = 0x62,
  76. /*
  77. * 32 bit generation number, 40 bit i_pos.
  78. */
  79. FILEID_FAT_WITHOUT_PARENT = 0x71,
  80. /*
  81. * 32 bit generation number, 40 bit i_pos,
  82. * 32 bit parent generation number, 40 bit parent i_pos
  83. */
  84. FILEID_FAT_WITH_PARENT = 0x72,
  85. /*
  86. * 128 bit child FID (struct lu_fid)
  87. * 128 bit parent FID (struct lu_fid)
  88. */
  89. FILEID_LUSTRE = 0x97,
  90. /*
  91. * 64 bit unique kernfs id
  92. */
  93. FILEID_KERNFS = 0xfe,
  94. /*
  95. * Filesystems must not use 0xff file ID.
  96. */
  97. FILEID_INVALID = 0xff,
  98. };
  99. struct fid {
  100. union {
  101. struct {
  102. u32 ino;
  103. u32 gen;
  104. u32 parent_ino;
  105. u32 parent_gen;
  106. } i32;
  107. struct {
  108. u32 block;
  109. u16 partref;
  110. u16 parent_partref;
  111. u32 generation;
  112. u32 parent_block;
  113. u32 parent_generation;
  114. } udf;
  115. __u32 raw[0];
  116. };
  117. };
  118. /**
  119. * struct export_operations - for nfsd to communicate with file systems
  120. * @encode_fh: encode a file handle fragment from a dentry
  121. * @fh_to_dentry: find the implied object and get a dentry for it
  122. * @fh_to_parent: find the implied object's parent and get a dentry for it
  123. * @get_name: find the name for a given inode in a given directory
  124. * @get_parent: find the parent of a given directory
  125. * @commit_metadata: commit metadata changes to stable storage
  126. *
  127. * See Documentation/filesystems/nfs/exporting.rst for details on how to use
  128. * this interface correctly.
  129. *
  130. * encode_fh:
  131. * @encode_fh should store in the file handle fragment @fh (using at most
  132. * @max_len bytes) information that can be used by @decode_fh to recover the
  133. * file referred to by the &struct dentry @de. If the @connectable flag is
  134. * set, the encode_fh() should store sufficient information so that a good
  135. * attempt can be made to find not only the file but also it's place in the
  136. * filesystem. This typically means storing a reference to de->d_parent in
  137. * the filehandle fragment. encode_fh() should return the fileid_type on
  138. * success and on error returns 255 (if the space needed to encode fh is
  139. * greater than @max_len*4 bytes). On error @max_len contains the minimum
  140. * size(in 4 byte unit) needed to encode the file handle.
  141. *
  142. * fh_to_dentry:
  143. * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
  144. * fragment (@fh, @fh_len). It should return a &struct dentry which refers
  145. * to the same file that the file handle fragment refers to. If it cannot,
  146. * it should return a %NULL pointer if the file cannot be found, or an
  147. * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
  148. * Any other error code is treated like %NULL, and will cause an %ESTALE error
  149. * for callers of exportfs_decode_fh().
  150. * Any suitable dentry can be returned including, if necessary, a new dentry
  151. * created with d_alloc_root. The caller can then find any other extant
  152. * dentries by following the d_alias links.
  153. *
  154. * fh_to_parent:
  155. * Same as @fh_to_dentry, except that it returns a pointer to the parent
  156. * dentry if it was encoded into the filehandle fragment by @encode_fh.
  157. *
  158. * get_name:
  159. * @get_name should find a name for the given @child in the given @parent
  160. * directory. The name should be stored in the @name (with the
  161. * understanding that it is already pointing to a %NAME_MAX+1 sized
  162. * buffer. get_name() should return %0 on success, a negative error code
  163. * or error. @get_name will be called without @parent->i_mutex held.
  164. *
  165. * get_parent:
  166. * @get_parent should find the parent directory for the given @child which
  167. * is also a directory. In the event that it cannot be found, or storage
  168. * space cannot be allocated, a %ERR_PTR should be returned.
  169. *
  170. * commit_metadata:
  171. * @commit_metadata should commit metadata changes to stable storage.
  172. *
  173. * Locking rules:
  174. * get_parent is called with child->d_inode->i_mutex down
  175. * get_name is not (which is possibly inconsistent)
  176. */
  177. struct export_operations {
  178. int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
  179. struct inode *parent);
  180. struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
  181. int fh_len, int fh_type);
  182. struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
  183. int fh_len, int fh_type);
  184. int (*get_name)(struct dentry *parent, char *name,
  185. struct dentry *child);
  186. struct dentry * (*get_parent)(struct dentry *child);
  187. int (*commit_metadata)(struct inode *inode);
  188. int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
  189. int (*map_blocks)(struct inode *inode, loff_t offset,
  190. u64 len, struct iomap *iomap,
  191. bool write, u32 *device_generation);
  192. int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
  193. int nr_iomaps, struct iattr *iattr);
  194. };
  195. extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
  196. int *max_len, struct inode *parent);
  197. extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
  198. int *max_len, int connectable);
  199. extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
  200. int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
  201. void *context);
  202. /*
  203. * Generic helpers for filesystems.
  204. */
  205. extern struct dentry *generic_fh_to_dentry(struct super_block *sb,
  206. struct fid *fid, int fh_len, int fh_type,
  207. struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
  208. extern struct dentry *generic_fh_to_parent(struct super_block *sb,
  209. struct fid *fid, int fh_len, int fh_type,
  210. struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
  211. #endif /* LINUX_EXPORTFS_H */