From: Karel Zak <kzak@redhat.com>
Date: Mon, 5 Jun 2023 10:59:41 +0000 (+0200)
Subject: libmount: use mount(2) for remount on Linux < 5.14
X-Git-Tag: v2.40-rc1~401^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=71b01d2a3760f36a1e81d422237f661fd07a72ad;p=thirdparty%2Futil-linux.git

libmount: use mount(2) for remount on Linux < 5.14

It seems mount_setattr() is supported on Linux < 5.14, but it's without
MOUNT_ATTR_NOSYMFOLLOW. That's problem for remount where we reset all
VFS flags.

The most simple (but not elegant) is to check for kernel version and
fallback to mount(2) on remount.

Addresses: https://github.com/util-linux/util-linux/issues/2283
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c
index 91483afa68..5a7e30fea0 100644
--- a/libmount/src/hook_mount.c
+++ b/libmount/src/hook_mount.c
@@ -46,6 +46,7 @@
 #include "mountP.h"
 #include "fileutils.h"	/* statx() fallback */
 #include "mount-api-utils.h"
+#include "linux_version.h"
 
 #include <inttypes.h>
 
@@ -693,6 +694,13 @@ static int hook_prepare(struct libmnt_context *cxt,
 	if (!rc
 	    && cxt->helper == NULL
 	    && (set != 0 || clr != 0 || (flags & MS_REMOUNT))) {
+		/*
+		 * mount_setattr() supported, but not usable for remount
+		 * https://github.com/torvalds/linux/commit/dd8b477f9a3d8edb136207acb3652e1a34a661b7
+		 */
+		if (get_linux_version() < KERNEL_VERSION(5, 14, 0))
+			goto enosys;
+
 		if (!mount_setattr_is_supported())
 			goto enosys;