[PATCH v2] overlay: notrun if upper fs does not support d_type

[Xiong Zhou <xzhou@redhat.com>]

Overlayfs whiteout can be visible if underlying upper fs does not
support d_type. Kernel commit
	45aebea (ovl: Ensure upper filesystem supports d_type)
prevents mounting overlayfs like this since v4.6-rc1.

Check upper fs before mounting overlay, mark as not run if needs.

Signed-off-by: Xiong Zhou <xzhou@redhat.com>
---

v2: use case to make this less ugly..


 common/rc | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/common/rc b/common/rc
index 8bec836..946b354 100644
--- a/common/rc
+++ b/common/rc
@@ -273,6 +273,22 @@ _overlay_mount()
 	local dir=$1
 	local mnt=$2
 	shift 2
+
+	local upper_fst=$(df --output=fstype $dir | tail -1)
+	case "$upper_fst" in
+	xfs)
+		if ! xfs_info $dir | grep -q "ftype=1" ; then
+			_notrun "upper fs needs to support d_type"
+		fi
+		;;
+	ext2|ext3|ext4)
+		if ! tune2fs -l $(df --output=source $dir | tail -1) | \
+		   grep -q filetype ; then
+			_notrun "upper fs needs to support d_type"
+		fi
+		;;
+	esac
+
 	mkdir -p $dir/$OVERLAY_UPPER_DIR
 	mkdir -p $dir/$OVERLAY_LOWER_DIR
 	mkdir -p $dir/$OVERLAY_WORK_DIR
-- 
2.5.5