NFSv4.1/pnfs: Ensure we handle the error NFS4ERR_RETURNCONFLICT

Once the client has processed the CB_LAYOUTRECALL, but has not yet
successfully returned the layout, the server is supposed to switch to
returning NFS4ERR_RETURNCONFLICT. This patch ensures that we handle
that return value correctly.

Fixes: 183d9e7 ("pnfs: rework LAYOUTGET retry handling")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Author: Trond Myklebust

fs/nfs/nfs4proc.c

@@ -170,6 +170,7 @@ static int nfs4_map_errors(int err)
 	case -NFS4ERR_RESOURCE:
 	case -NFS4ERR_LAYOUTTRYLATER:
 	case -NFS4ERR_RECALLCONFLICT:
+	case -NFS4ERR_RETURNCONFLICT:
 		return -EREMOTEIO;
 	case -NFS4ERR_WRONGSEC:
 	case -NFS4ERR_WRONG_CRED:
@@ -558,6 +559,7 @@ static int nfs4_do_handle_exception(struct nfs_server *server,
 		case -NFS4ERR_GRACE:
 		case -NFS4ERR_LAYOUTTRYLATER:
 		case -NFS4ERR_RECALLCONFLICT:
+		case -NFS4ERR_RETURNCONFLICT:
 			exception->delay = 1;
 			return 0;
 
@@ -9691,6 +9693,7 @@ nfs4_layoutget_handle_exception(struct rpc_task *task,
 		status = -EBUSY;
 		break;
 	case -NFS4ERR_RECALLCONFLICT:
+	case -NFS4ERR_RETURNCONFLICT:
 		status = -ERECALLCONFLICT;
 		break;
 	case -NFS4ERR_DELEG_REVOKED: