NFSv4.1/pnfs: Add a tracepoint for return-on-close events

Allow tracing of return-on-close.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4trace.h b/fs/nfs/nfs4trace.h
index 470af1a..0b67f782 100644
--- a/fs/nfs/nfs4trace.h
+++ b/fs/nfs/nfs4trace.h
@@ -1136,6 +1136,7 @@
 
 DEFINE_NFS4_INODE_EVENT(nfs4_layoutcommit);
 DEFINE_NFS4_INODE_EVENT(nfs4_layoutreturn);
+DEFINE_NFS4_INODE_EVENT(nfs4_layoutreturn_on_close);
 
 #endif /* CONFIG_NFS_V4_1 */