Merge tag 'vfs-6.13.exportfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs exportfs updates from Christian Brauner:
 "This contains work to bring NFS connectable file handles to userspace
  servers.

  The name_to_handle_at() system call is extended to encode connectable
  file handles. Such file handles can be resolved to an open file with a
  connected path. So far userspace NFS servers couldn't make use of this
  functionality even though the kernel does already support it. This is
  achieved by introducing a new flag for name_to_handle_at().

  Similarly, the open_by_handle_at() system call is tought to understand
  connectable file handles explicitly created via name_to_handle_at()"

* tag 'vfs-6.13.exportfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs: open_by_handle_at() support for decoding "explicit connectable" file handles
  fs: name_to_handle_at() support for "explicit connectable" file handles
  fs: prepare for "explicit connectable" file handles

include/linux/exportfs.h

@@ -160,6 +160,19 @@ struct fid {
 #define EXPORT_FH_FID		0x2 /* File handle may be non-decodeable */
 #define EXPORT_FH_DIR_ONLY	0x4 /* Only decode file handle for a directory */
 
+/*
+ * Filesystems use only lower 8 bits of file_handle type for fid_type.
+ * name_to_handle_at() uses upper 16 bits of type as user flags to be
+ * interpreted by open_by_handle_at().
+ */
+#define FILEID_USER_FLAGS_MASK	0xffff0000
+#define FILEID_USER_FLAGS(type) ((type) & FILEID_USER_FLAGS_MASK)
+
+/* Flags supported in encoded handle_type that is exported to user */
+#define FILEID_IS_CONNECTABLE	0x10000
+#define FILEID_IS_DIR		0x20000
+#define FILEID_VALID_USER_FLAGS	(FILEID_IS_CONNECTABLE | FILEID_IS_DIR)
+
 /**
  * struct export_operations - for nfsd to communicate with file systems
  * @encode_fh:      encode a file handle fragment from a dentry