NFSv4.1: filelayout driver specific code for COMMIT

Implement all the hooks created in the previous patches.
This requires exporting quite a few functions and adding a few
structure fields.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 477a2e5..229e586 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1470,6 +1470,7 @@
 	nfsi->delegation_state = 0;
 	init_rwsem(&nfsi->rwsem);
 	nfsi->layout = NULL;
+	atomic_set(&nfsi->commits_outstanding, 0);
 #endif
 }