NFSv4.2: another fix for listxattr

Currently, when the server supports NFS4.1 security labels then
security.selinux label in included twice. Instead, only add it
when the server doesn't possess security label support.

Fixes: 243fea1 ("NFSv4.2: fix listxattr to return selinux security label")
Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
Link: https://lore.kernel.org/r/20250722205641.79394-1-okorniev@redhat.com
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: Olga Kornievskaia

fs/nfs/nfs4proc.c

@@ -10883,7 +10883,7 @@ const struct nfs4_minor_version_ops *nfs_v4_minor_ops[] = {
 
 static ssize_t nfs4_listxattr(struct dentry *dentry, char *list, size_t size)
 {
-	ssize_t error, error2, error3, error4;
+	ssize_t error, error2, error3, error4 = 0;
 	size_t left = size;
 
 	error = generic_listxattr(dentry, list, left);
@@ -10911,9 +10911,11 @@ static ssize_t nfs4_listxattr(struct dentry *dentry, char *list, size_t size)
 		left -= error3;
 	}
 
-	error4 = security_inode_listsecurity(d_inode(dentry), list, left);
-	if (error4 < 0)
-		return error4;
+	if (!nfs_server_capable(d_inode(dentry), NFS_CAP_SECURITY_LABEL)) {
+		error4 = security_inode_listsecurity(d_inode(dentry), list, left);
+		if (error4 < 0)
+			return error4;
+	}
 
 	error += error2 + error3 + error4;
 	if (size && error > size)