Use the fstatfs64/statfs64 syscalls instead of the emulation with fstatfs/statfs
The syscalls are supported at least since kernel 2.6.13, the oldest on Fritz Boxes
--- libc/misc/statfs/fstatfs64.c
+++ libc/misc/statfs/fstatfs64.c
@@ -22,9 +22,10 @@
 #include <errno.h>
 #include <string.h>
 #include <sys/statfs.h>
-#include <sys/statvfs.h>
+#include <sys/syscall.h>
 #include <stddef.h>
 
+#if !defined __NR_fstatfs64
 extern __typeof(fstatfs) __libc_fstatfs;
 
 /* Return information about the filesystem on which FD resides.  */
@@ -51,4 +52,12 @@
 
     return 0;
 }
+#else
+int fstatfs64(int fd, struct statfs64 *buf)
+{
+	/* Signature has 2 arguments but syscalls wants 3 */
+	return INLINE_SYSCALL(fstatfs64, 3, fd, sizeof(*buf), buf);
+}
+#endif
+
 libc_hidden_def(fstatfs64)
diff --git a/libc/misc/statfs/statfs64.c b/libc/misc/statfs/statfs64.c
index ce8211b..b1a33b7 100644
--- libc/misc/statfs/statfs64.c
+++ libc/misc/statfs/statfs64.c
@@ -22,9 +22,11 @@
 #include <string.h>
 #include <stddef.h>
 #include <sys/statfs.h>
+#include <sys/syscall.h>
 
 extern __typeof(statfs) __libc_statfs;
 
+#if !defined __NR_statfs64
 /* Return information about the filesystem on which FILE resides.  */
 int statfs64 (const char *file, struct statfs64 *buf)
 {
@@ -49,4 +51,11 @@ int statfs64 (const char *file, struct statfs64 *buf)
 
     return 0;
 }
+#else
+int statfs64 (const char *file, struct statfs64 *buf)
+{
+    return INLINE_SYSCALL(statfs64, 3, file, sizeof(*buf), buf);
+}
+#endif
+
 libc_hidden_def(statfs64)