From bfef0cfab41cb4894bc5cf8b93e76327ac04b9b9 Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton@kernel.org>
Date: Tue, 18 Oct 2022 07:47:54 -0400
Subject: [PATCH] nfsd: ignore requests to disable unsupported versions

[ Upstream commit 8e823bafff2308753d430566256c83d8085952da ]

The kernel currently errors out if you attempt to enable or disable a
version that it doesn't recognize. Change it to ignore attempts to
disable an unrecognized version. If we don't support it, then there is
no harm in doing so.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/nfsd/nfsctl.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 573de0d49e17..c21f5815d726 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -601,7 +601,9 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
 				}
 				break;
 			default:
-				return -EINVAL;
+				/* Ignore requests to disable non-existent versions */
+				if (cmd == NFSD_SET)
+					return -EINVAL;
 			}
 			vers += len + 1;
 		} while ((len = qword_get(&mesg, vers, size)) > 0);