nfs: Add ALLOCATE support

This patch adds support for using the NFS v4.2 operation ALLOCATE to
preallocate data in a file.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 356acc2..2b28a21 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -490,6 +490,7 @@
 
 	/* nfs42 */
 	NFSPROC4_CLNT_SEEK,
+	NFSPROC4_CLNT_ALLOCATE,
 };
 
 /* nfs41 types */