From e385f541859982337f60cadcaaadc96301b26dcb Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Mon, 4 Mar 2024 15:58:35 -0800
Subject: [PATCH] fix: nLink is unreliable on all filesystems (#19187)

ext4, xfs support this behavior however
btrfs, nfs may not support it properly.

in-case when we see Nlink < 2 then we know
that we need to fallback on readdir()

fixes a regression from #19100

fixes #19181
---
 cmd/is-dir-empty_linux.go | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/cmd/is-dir-empty_linux.go b/cmd/is-dir-empty_linux.go
index f7ad4f74f..c205955f8 100644
--- a/cmd/is-dir-empty_linux.go
+++ b/cmd/is-dir-empty_linux.go
@@ -20,7 +20,9 @@
 
 package cmd
 
-import "syscall"
+import (
+	"syscall"
+)
 
 // Returns true if no error and there is no object or prefix inside this directory
 func isDirEmpty(dirname string) bool {
@@ -28,5 +30,17 @@ func isDirEmpty(dirname string) bool {
 	if err := syscall.Stat(dirname, &stat); err != nil {
 		return false
 	}
-	return stat.Mode&syscall.S_IFMT == syscall.S_IFDIR && stat.Nlink < 3
+	if stat.Mode&syscall.S_IFMT == syscall.S_IFDIR && stat.Nlink == 2 {
+		return true
+	}
+	// On filesystems such as btrfs, nfs this is not true, so fallback
+	// to performing readdir() instead.
+	if stat.Mode&syscall.S_IFMT == syscall.S_IFDIR && stat.Nlink < 2 {
+		entries, err := readDirN(dirname, 1)
+		if err != nil {
+			return false
+		}
+		return len(entries) == 0
+	}
+	return false
 }