orangefs: record userspace version for feature compatbility

The client reports its version to the kernel on startup. We already test
that it is above the minimum version. Now we record it in a global
variable so code elsewhere can consult it before making a request the
client may not understand.

Signed-off-by: Martin Brandenburg <martin@omnibond.com>

fs/orangefs/orangefs-kernel.h

@@ -506,6 +506,8 @@ ssize_t orangefs_inode_read(struct inode *inode,
 /*
  * defined in devorangefs-req.c
  */
+extern uint32_t userspace_version;
+
 int orangefs_dev_init(void);
 void orangefs_dev_cleanup(void);
 int is_daemon_in_service(void);