apfstests/common/overlay

#
# overlayfs specific common functions.
#
. ./common/module

# Export overlayfs xattrs and constant value
export OVL_XATTR_OPAQUE="trusted.overlay.opaque"
export OVL_XATTR_REDIRECT="trusted.overlay.redirect"
export OVL_XATTR_IMPURE="trusted.overlay.impure"
export OVL_XATTR_ORIGIN="trusted.overlay.origin"
export OVL_XATTR_NLINK="trusted.overlay.nlink"
export OVL_XATTR_UPPER="trusted.overlay.upper"

# helper function to do the actual overlayfs mount operation
_overlay_mount_dirs()
{
	local lowerdir=$1
	local upperdir=$2
	local workdir=$3
	shift 3

	$MOUNT_PROG -t overlay -o lowerdir=$lowerdir -o upperdir=$upperdir \
		    -o workdir=$workdir `_common_dev_mount_options $*`
}

# Mount with same options/mnt/dev of scratch mount, but optionally
# with different lower/upper/work dirs
_overlay_scratch_mount_dirs()
{
	local lowerdir=$1
	local upperdir=$2
	local workdir=$3
	shift 3

	_overlay_mount_dirs $lowerdir $upperdir $workdir \
				$* $OVL_BASE_SCRATCH_MNT $SCRATCH_MNT
}

_overlay_mkdirs()
{
	local dir=$1

	mkdir -p $dir/$OVL_UPPER
	mkdir -p $dir/$OVL_LOWER
	mkdir -p $dir/$OVL_WORK
	mkdir -p $dir/$OVL_MNT
}

# Given a base fs dir, set up overlay directories and mount on the given mnt.
# The dir is used as the mount device so it can be seen from df or mount
_overlay_mount()
{
	local dir=$1
	local mnt=$2
	shift 2

	_supports_filetype $dir || _notrun "upper fs needs to support d_type"

	_overlay_mkdirs $dir

	_overlay_mount_dirs $dir/$OVL_LOWER $dir/$OVL_UPPER $dir/$OVL_WORK \
				$* $dir $mnt
}

_overlay_base_mount()
{
	local devname=$1
	local mntname=$2
	local dev=$3
	local mnt=$4
	shift 4

	if [ -z "$dev" -o -z "$mnt" ] || \
		_check_mounted_on $devname $dev $mntname $mnt; then
		# no base fs or already mounted
		return 0
	elif [ $? -ne 1 ]; then
		# base fs mounted but not on mount point
		return 1
	fi

	_mount $* $dev $mnt
}

_overlay_base_test_mount()
{
	_overlay_base_mount OVL_BASE_TEST_DEV OVL_BASE_TEST_DIR \
			"$OVL_BASE_TEST_DEV" "$OVL_BASE_TEST_DIR" \
			$TEST_FS_MOUNT_OPTS $SELINUX_MOUNT_OPTIONS
}

_overlay_test_mount()
{
	_overlay_base_test_mount && \
		_overlay_mount $OVL_BASE_TEST_DIR $TEST_DIR $*
}

_overlay_base_scratch_mount()
{
	_overlay_base_mount OVL_BASE_SCRATCH_DEV OVL_BASE_SCRATCH_MNT \
			"$OVL_BASE_SCRATCH_DEV" "$OVL_BASE_SCRATCH_MNT" \
			$OVL_BASE_MOUNT_OPTIONS $SELINUX_MOUNT_OPTIONS
}

_overlay_scratch_mount()
{
	_overlay_base_scratch_mount && \
		_overlay_mount $OVL_BASE_SCRATCH_MNT $SCRATCH_MNT $*
}

_overlay_base_unmount()
{
	local dev=$1
	local mnt=$2

	[ -n "$dev" -a -n "$mnt" ] || return 0

	$UMOUNT_PROG $mnt
}

_overlay_test_unmount()
{
	$UMOUNT_PROG $TEST_DIR
	_overlay_base_unmount "$OVL_BASE_TEST_DEV" "$OVL_BASE_TEST_DIR"
}

_overlay_scratch_unmount()
{
	$UMOUNT_PROG $SCRATCH_MNT
	_overlay_base_unmount "$OVL_BASE_SCRATCH_DEV" "$OVL_BASE_SCRATCH_MNT"
}

# Check that a specific overlayfs feature is supported
__check_scratch_overlay_feature()
{
	local feature=$1

	# overalyfs features (e.g. redirect_dir, index) are
	# configurable from Kconfig (the build default), by module
	# parameter (the system default) and per mount by mount
	# option ${feature}=[on|off].
	#
	# If the module parameter does not exist then there is no
	# point in checking the mount option.
	local default=`_get_fs_module_param ${feature}`
	[ "$default" = Y ] || [ "$default" = N ] || \
		_notrun "feature '${feature}' not supported by ${FSTYP}"

	# Check options to be sure. For example, Overlayfs will fallback to
	# index=off if underlying fs does not support file handles.
	# Overlayfs only displays mount option if it differs from the default.
	# Overlayfs may enable the feature, but fallback to read-only mount.
	((( [ "$default" = N ] && _fs_options $SCRATCH_DEV | grep -q "${feature}=on" ) || \
	  ( [ "$default" = Y ] && ! _fs_options $SCRATCH_DEV | grep -q "${feature}=off" )) && \
	    touch $SCRATCH_MNT/foo 2>/dev/null ) || \
	        _notrun "${FSTYP} feature '${feature}' cannot be enabled on ${SCRATCH_DEV}"
}

# Require a set of overlayfs features
_require_scratch_overlay_features()
{
	local features=( $* )
	local opts="rw"

	for feature in ${features[*]}; do
		opts+=",${feature}=on"
	done

	_scratch_mkfs > /dev/null 2>&1
	_try_scratch_mount -o $opts || \
		_notrun "overlay options '$opts' cannot be enabled on ${SCRATCH_DEV}"

	for feature in ${features[*]}; do
		__check_scratch_overlay_feature ${feature}
	done

	_scratch_unmount
}

# Helper function to check underlying dirs of overlay filesystem
_overlay_fsck_dirs()
{
	local lowerdir=$1
	local upperdir=$2
	local workdir=$3
	shift 3

	[[ ! -x "$FSCK_OVERLAY_PROG" ]] && return 0

	$FSCK_OVERLAY_PROG -o lowerdir=$lowerdir -o upperdir=$upperdir \
			   -o workdir=$workdir $*
}