diff options
Diffstat (limited to 'include/linux/exportfs.h')
| -rw-r--r-- | include/linux/exportfs.h | 54 |
1 files changed, 42 insertions, 12 deletions
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index f0cf2714ec52..8bcdba28b406 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -200,10 +200,14 @@ struct handle_to_path_ctx { * @get_parent: find the parent of a given directory * @commit_metadata: commit metadata changes to stable storage * + * Methods for open_by_handle(2) syscall with special kernel file systems: + * @permission: custom permission for opening a file by handle + * @open: custom open routine for opening file by handle + * * See Documentation/filesystems/nfs/exporting.rst for details on how to use - * this interface correctly. + * this interface correctly and the definition of the flags. * - * encode_fh: + * @encode_fh: * @encode_fh should store in the file handle fragment @fh (using at most * @max_len bytes) information that can be used by @decode_fh to recover the * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit @@ -215,7 +219,7 @@ struct handle_to_path_ctx { * greater than @max_len*4 bytes). On error @max_len contains the minimum * size(in 4 byte unit) needed to encode the file handle. * - * fh_to_dentry: + * @fh_to_dentry: * @fh_to_dentry is given a &struct super_block (@sb) and a file handle * fragment (@fh, @fh_len). It should return a &struct dentry which refers * to the same file that the file handle fragment refers to. If it cannot, @@ -227,31 +231,48 @@ struct handle_to_path_ctx { * created with d_alloc_root. The caller can then find any other extant * dentries by following the d_alias links. * - * fh_to_parent: + * @fh_to_parent: * Same as @fh_to_dentry, except that it returns a pointer to the parent * dentry if it was encoded into the filehandle fragment by @encode_fh. * - * get_name: + * @get_name: * @get_name should find a name for the given @child in the given @parent * directory. The name should be stored in the @name (with the - * understanding that it is already pointing to a %NAME_MAX+1 sized + * understanding that it is already pointing to a %NAME_MAX + 1 sized * buffer. get_name() should return %0 on success, a negative error code * or error. @get_name will be called without @parent->i_rwsem held. * - * get_parent: + * @get_parent: * @get_parent should find the parent directory for the given @child which * is also a directory. In the event that it cannot be found, or storage * space cannot be allocated, a %ERR_PTR should be returned. * - * permission: - * Allow filesystems to specify a custom permission function. + * @permission: + * Allow filesystems to specify a custom permission function for the + * open_by_handle_at(2) syscall instead of the default permission check. + * This custom permission function is not respected by nfsd. * - * open: - * Allow filesystems to specify a custom open function. + * @open: + * Allow filesystems to specify a custom open function for the + * open_by_handle_at(2) syscall instead of the default file_open_root(). + * This custom open function is not respected by nfsd. * - * commit_metadata: + * @commit_metadata: * @commit_metadata should commit metadata changes to stable storage. * + * @get_uuid: + * Get a filesystem unique signature exposed to clients. + * + * @map_blocks: + * Map and, if necessary, allocate blocks for a layout. + * + * @commit_blocks: + * Commit blocks in a layout once the client is done with them. + * + * @flags: + * Allows the filesystem to communicate to nfsd that it may want to do things + * differently when dealing with it. + * * Locking rules: * get_parent is called with child->d_inode->i_rwsem down * get_name is not (which is possibly inconsistent) @@ -317,6 +338,15 @@ static inline bool exportfs_can_decode_fh(const struct export_operations *nop) return nop && nop->fh_to_dentry; } +static inline bool exportfs_may_export(const struct export_operations *nop) +{ + /* + * Do not allow nfs export for filesystems with custom ->open() or + * ->permission() ops, which nfsd does not respect (e.g. pidfs, nsfs). + */ + return exportfs_can_decode_fh(nop) && !nop->open && !nop->permission; +} + static inline bool exportfs_can_encode_fh(const struct export_operations *nop, int fh_flags) { |