NFS/pNFS: Fix a leak of the layout 'plh_outstanding' counter

If we exit _lgopen_prepare_attached() without setting a layout, we will
currently leak the plh_outstanding counter.

Fixes: 411ae722 ("pNFS: Wait for stale layoutget calls to complete in pnfs_update_layout()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/pnfs.c

@@ -2244,6 +2244,7 @@ static void _lgopen_prepare_attached(struct nfs4_opendata *data,
 					     &rng, GFP_KERNEL);
 	if (!lgp) {
 		pnfs_clear_first_layoutget(lo);
+		nfs_layoutget_end(lo);
 		pnfs_put_layout_hdr(lo);
 		return;
 	}