NFSv4.1 handle DS stateid errors

Handle DS READ and WRITE stateid errors by recovering the stateid on the MDS.

NFS4ERR_OLD_STATEID is ignored as the client always sends a
state sequenceid of zero for DS READ and WRITE stateids.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/delegation.c

@@ -474,6 +474,7 @@ void nfs_remove_bad_delegation(struct inode *inode)
 		nfs_free_delegation(delegation);
 	}
 }
+EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
 
 /**
  * nfs_expire_all_delegation_types