pNFS: Ensure we commit the layout if it has been invalidated

If the layout is being invalidated on the server, then we must
invoke nfs_commit_inode() to ensure any commits to the DS get
cleared out.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
index c81c619..87f5b7b 100644
--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -379,6 +379,7 @@ nfs42_layoutstat_done(struct rpc_task *task, void *calldata)
 			pnfs_mark_layout_stateid_invalid(lo, &head);
 			spin_unlock(&inode->i_lock);
 			pnfs_free_lseg_list(&head);
+			nfs_commit_inode(inode, 0);
 		} else
 			spin_unlock(&inode->i_lock);
 		break;