NFSv4.1: Pin the inode and super block in asynchronous layoutreturns

If we're sending an asynchronous layoutreturn, then we need to ensure
that the inode and the super block remain pinned.

Cc: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>

fs/nfs/nfs4proc.c

@@ -7856,6 +7856,7 @@ static void nfs4_layoutreturn_release(void *calldata)
 	lo->plh_block_lgets--;
 	spin_unlock(&lo->plh_inode->i_lock);
 	pnfs_put_layout_hdr(lrp->args.layout);
+	nfs_iput_and_deactive(lrp->inode);
 	kfree(calldata);
 	dprintk("<-- %s\n", __func__);
 }
@@ -7880,23 +7881,25 @@ int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp, bool sync)
 		.rpc_message = &msg,
 		.callback_ops = &nfs4_layoutreturn_call_ops,
 		.callback_data = lrp,
-		.flags = RPC_TASK_ASYNC,
 	};
 	int status = 0;
 
 	dprintk("--> %s\n", __func__);
+	if (!sync) {
+		lrp->inode = nfs_igrab_and_active(lrp->args.inode);
+		if (!lrp->inode) {
+			nfs4_layoutreturn_release(lrp);
+			return -EAGAIN;
+		}
+		task_setup_data.flags |= RPC_TASK_ASYNC;
+	}
 	nfs4_init_sequence(&lrp->args.seq_args, &lrp->res.seq_res, 1);
 	task = rpc_run_task(&task_setup_data);
 	if (IS_ERR(task))
 		return PTR_ERR(task);
-	if (sync == false)
-		goto out;
-	status = nfs4_wait_for_completion_rpc_task(task);
-	if (status != 0)
-		goto out;
+	if (sync)
 		status = task->tk_status;
 	trace_nfs4_layoutreturn(lrp->args.inode, status);
-out:
 	dprintk("<-- %s status=%d\n", __func__, status);
 	rpc_put_task(task);
 	return status;

include/linux/nfs_xdr.h

@@ -310,6 +310,7 @@ struct nfs4_layoutreturn {
 	struct nfs4_layoutreturn_res res;
 	struct rpc_cred *cred;
 	struct nfs_client *clp;
+	struct inode *inode;
 	int rpc_status;
 };