Description: Disable swapfile's CoW for CoW filesystems
 Touch swapfile before trying to set the CoW attribute.
Author: Louis Jackman <ljackman@protonmail.com>
Origin: https://salsa.debian.org/debian/dphys-swapfile/-/merge_requests/2
Origin: https://salsa.debian.org/debian/dphys-swapfile/-/merge_requests/3

--- a/dphys-swapfile
+++ b/dphys-swapfile
@@ -144,6 +144,16 @@
       grep -v "^${CONF_SWAPFILE}" /etc/fstab > /etc/.fstab
       mv /etc/.fstab /etc/fstab
 
+      # the later copy-on-write chattr wants an empty file rather than an
+      # already-populated file
+      touch "${CONF_SWAPFILE}"
+
+      # disable copy-on-write on the swapfile, for copy-on-write filesystems
+      #
+      # to avoid errors on non-copy-on-write filesystems, suppress error with
+      #`-f` and `|| true`
+      chattr -f +C "${CONF_SWAPFILE}" || true
+
       dd if=/dev/zero of="${CONF_SWAPFILE}" bs=1048576 \
         count="${CONF_SWAPSIZE}" 2> /dev/null