From: Reinhard Tartler <siretart@debian.org>
Date: Tue, 10 Jan 2023 14:45:12 +0800
Subject: Fix FTBFS btrfs-progs 6.1

Bugs-Debian: #1027116
---
 drivers/btrfs/btrfs.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/btrfs/btrfs.go b/drivers/btrfs/btrfs.go
index 0b5d1c5..79be406 100644
--- a/drivers/btrfs/btrfs.go
+++ b/drivers/btrfs/btrfs.go
@@ -6,6 +6,9 @@ package btrfs
 /*
 #include <stdlib.h>
 #include <dirent.h>
+
+// keep struct field name compatible with btrfs-progs < 6.1.
+#define max_referenced max_rfer
 #include <btrfs/ioctl.h>
 #include <btrfs/ctree.h>
 
@@ -382,7 +385,7 @@ func subvolLimitQgroup(path string, size uint64) error {
 	defer closeDir(dir)
 
 	var args C.struct_btrfs_ioctl_qgroup_limit_args
-	args.lim.max_referenced = C.__u64(size)
+	args.lim.max_rfer = C.__u64(size)
 	args.lim.flags = C.BTRFS_QGROUP_LIMIT_MAX_RFER
 	_, _, errno := unix.Syscall(unix.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QGROUP_LIMIT,
 		uintptr(unsafe.Pointer(&args)))