From 63de3e9917c9cb3601727b0f50885cd31df20be0 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Tue, 9 Aug 2022 15:38:42 +0200
Subject: [slx-dmsetup] Add linear swap space if slx.swap is in command line

.... and if we don't seem to have an existing swap partition
---
 modules.d/slx-dmsetup/scripts/dmsetup-slx-device | 52 ++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 4 deletions(-)

diff --git a/modules.d/slx-dmsetup/scripts/dmsetup-slx-device b/modules.d/slx-dmsetup/scripts/dmsetup-slx-device
index 4b087130..2dcd7eb3 100755
--- a/modules.d/slx-dmsetup/scripts/dmsetup-slx-device
+++ b/modules.d/slx-dmsetup/scripts/dmsetup-slx-device
@@ -61,7 +61,7 @@ handle_unit() {
 declare -ag linear snapshot thin_snapshot thin_volume
 parse_config() {
 	[ -z "$1" ] && return 1
-	while IFS= read -r line; do
+	while IFS= read -r line || [ -n "$line" ]; do
 		[ -z "$line" ] && continue
 		read -r type name range crypt ignore <<< "$line"
 		type=${type//-/_} # to use the type as variable in eval
@@ -428,6 +428,7 @@ find_ntfs_partitions() {
 		return
 	fi
 	local part sum
+	ntfs_extra_space_sz=0
 	for part in /dev/disk/by-partuuid/*; do
 		# Only count ranges >= 256MB, sum will be in number of 512b blocks
 		sum="$( ntfsfree --block-size 512 --min-size "$(( 256 * 1024 * 1024 ))" "$part" \
@@ -435,14 +436,22 @@ find_ntfs_partitions() {
 		# Only consider volume if sum of these ranges > 1GB (this is BLOCKS, not bytes)
 		(( "$sum" > 2 * 1024 * 1024 )) || continue
 		echo "$sum $part" # only thing in loop going to stdout
+		(( ntfs_extra_space_sz += sum ))
 	done | sort -nr > "$ntfs_list"
 }
+ntfs_extra_space_sz=0
 
 ###
 ##	MAIN
 ###
 
 . /etc/openslx
+
+. slx-tools
+# "Preload" functions by executing them NOT in a subshell
+dev_find_partitions &> /dev/null
+dev_swap_version &> /dev/null
+
 # This is the main variable driving this script
 declare -g writable_device=
 if [ -z "$SLX_WRITABLE_DEVICE_IDENTIFIER" ]; then
@@ -455,7 +464,7 @@ fi
 if [ -n "$SLX_WRITABLE_DEVICE_IDENTIFIER" ]; then
 	# only first one for now TODO create linear devices of all ID44s
 	declare -a writable_devices
-	writable_devices=( $( slx-tools dev_find_partitions "${SLX_WRITABLE_DEVICE_IDENTIFIER[@]}" ) )
+	writable_devices=( $( dev_find_partitions "${SLX_WRITABLE_DEVICE_IDENTIFIER[@]}" ) )
 	if [[ "${#writable_devices[@]}" -eq 0 && "$SLX_NTFSFREE" != "never" ]] || [ "$SLX_NTFSFREE" = "always" ]; then
 		find_ntfs_partitions
 	fi
@@ -526,9 +535,44 @@ declare -rg writable_device_sz="$( blockdev --getsz "$writable_device" )"
 
 # If SLX_WRITABLE_DEVICE_PARTITION_TABLE is not set, just do
 # regular thin-snapshot for the CoW layer, else parse it.
-if [ -n "$SLX_WRITABLE_DEVICE_PARTITION_TABLE" ]; then
-	parse_config "$SLX_WRITABLE_DEVICE_PARTITION_TABLE"
+if [ -z "$SLX_WRITABLE_DEVICE_PARTITION_TABLE" ]; then
+	SLX_WRITABLE_DEVICE_PARTITION_TABLE="thin-snapshot root 100% 0"
 fi
+
+# extra swap?
+if grep -qFw 'slx.swap' "/proc/cmdline"; then
+	# Only if our basic writable_device is large enough, or we have ntfs backup
+	do_swap_sz=0
+	if (( writable_device_sz > 80078125 )); then
+		# more than ~40GB, go ahead
+		do_swap_sz="$(( ( writable_device_sz - 70312500 ) / 2 ))"
+		# cap to 6GB
+		(( do_swap_sz > 11718750 )) && do_swap_sz=11718750
+	elif [ "$SLX_NTFSFREE" = "backup" ] \
+			&& (( ntfs_extra_space_sz > 70312500 )) && (( writable_device_sz > 11718750 )); then
+		# more than 40GB NTFS backup space, more than 6GB ID44, make 4GB swap
+		do_swap_sz=7812500
+	fi
+	# Check how many we have and if they're regular, unencrypted ones.
+	# If it's plenty, don't cut out swap from our backing device
+	swap_sz=0
+	for part in $( dev_find_partitions "82" "0657fd6d-a4ab-43c4-84e5-0933c84b4f4f" ); do
+		dev_swap_version "$part" &> /dev/null || continue
+		this_sz="$( blockdev --getsz "$part" )"
+		(( this_sz > 0 )) && (( swap_sz += this_sz ))
+	done
+	echo "Have existing swap of $swap_sz blocks"
+	# Go ahead with swap? Only if existing swap < 4GB. If so, add line to table.
+	if (( do_swap_sz > 0 )) && (( swap_sz < 7812500 )); then
+		echo "Adding $do_swap_sz blocks of additional swap on backing dev"
+		skb="$(( do_swap_sz / 2 ))"
+		SLX_WRITABLE_DEVICE_PARTITION_TABLE="$( printf "%s\n%s" "linear slx-swap ${skb}K 0" \
+			"$SLX_WRITABLE_DEVICE_PARTITION_TABLE" )"
+	fi
+fi
+
+parse_config "$SLX_WRITABLE_DEVICE_PARTITION_TABLE"
+
 # Default to thin-snapshot, if none were configured
 if [ "${#snapshot[@]}" = 0 ] && [ "${#thin_snapshot[@]}" = 0 ]; then
 	parse_config "thin-snapshot root 100% 0"
-- 
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