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/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index eddda6c..807e07c 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -198,6 +198,7 @@
 
 	/* pNFS layout information */
 	struct pnfs_layout_hdr *layout;
+	atomic_t		commits_outstanding;
 #endif /* CONFIG_NFS_V4*/
 #ifdef CONFIG_NFS_FSCACHE
 	struct fscache_cookie	*fscache;