cifs: do not allow changing posix_paths during remount

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/fs_context.c

@@ -627,6 +627,10 @@ static void smb3_fs_context_free(struct fs_context *fc)
 static int smb3_verify_reconfigure_ctx(struct smb3_fs_context *new_ctx,
 				       struct smb3_fs_context *old_ctx)
 {
+	if (new_ctx->posix_paths != old_ctx->posix_paths) {
+		cifs_dbg(VFS, "can not change posixpaths during remount\n");
+		return -EINVAL;
+	}
 	if (new_ctx->sectype != old_ctx->sectype) {
 		cifs_dbg(VFS, "can not change sec during remount\n");
 		return -EINVAL;