[archiso] Change cowfile_size= behavior

Move from percent to explicit size and set a default of 256M (sparse)

Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@gmail.com>

1 files changed, 4 insertions, 12 deletions

diff --git a/hooks/archiso b/hooks/archiso
index 4c50566..8b90185 100644
--- a/hooks/archiso
+++ b/hooks/archiso
@@ -11,19 +11,13 @@ _mnt_fs() {
     ro_dev=$(losetup --find --show --read-only "${img}")
     echo ${ro_dev} >> /run/archiso/used_block_devices
     ro_dev_size=$(blockdev --getsz ${ro_dev})
-    if [[ "${cowfile_size}" == "100" ]]; then
-        rw_dev_size=${ro_dev_size}
-    else
-        # size calculation done in this way to avoid integer overflow when ro_dev_size is > 10.2G
-        rw_dev_size=$((ro_dev_size/100*cowfile_size))
-    fi
 
     if [[ "${cow_persistent}" == "P" ]]; then
         if [[ -f "/run/archiso/cowspace/${cow_directory}/${img_name}.cow" ]]; then
             msg ":: Found '/run/archiso/cowspace/${cow_directory}/${img_name}.cow', using as persistent."
         else
             msg ":: Creating '/run/archiso/cowspace/${cow_directory}/${img_name}.cow' as persistent."
-            dd of="/run/archiso/cowspace/${cow_directory}/${img_name}.cow" count=0 seek=${rw_dev_size} &> /dev/null
+            truncate -s "${cowfile_size}" "/run/archiso/cowspace/${cow_directory}/${img_name}.cow"
         fi
     else
         if [[ -f "/run/archiso/cowspace/${cow_directory}/${img_name}.cow" ]]; then
@@ -31,13 +25,13 @@ _mnt_fs() {
             rm -f "/run/archiso/cowspace/${cow_directory}/${img_name}.cow"
         fi
         msg ":: Creating '/run/archiso/cowspace/${cow_directory}/${img_name}.cow' as non-persistent."
-        dd of="/run/archiso/cowspace/${cow_directory}/${img_name}.cow" count=0 seek=${rw_dev_size} &> /dev/null
+        truncate -s "${cowfile_size}" "/run/archiso/cowspace/${cow_directory}/${img_name}.cow"
     fi
 
     rw_dev=$(losetup --find --show "/run/archiso/cowspace/${cow_directory}/${img_name}.cow")
     echo ${rw_dev} >> /run/archiso/used_block_devices
 
-    echo "0 ${ro_dev_size} snapshot ${ro_dev} ${rw_dev} ${cow_persistent} 8" | dmsetup create ${dm_snap_name}
+    dmsetup create ${dm_snap_name} --table "0 ${ro_dev_size} snapshot ${ro_dev} ${rw_dev} ${cow_persistent} 8"
 
     _mnt_dev "/dev/mapper/${dm_snap_name}" "${newroot}${mnt}" "-w"
     echo $(readlink -f /dev/mapper/${dm_snap_name}) >> /run/archiso/used_block_devices
@@ -108,9 +102,7 @@ run_hook() {
     [[ -z "${dm_snap_prefix}" ]] && dm_snap_prefix="arch"
     [[ -z "${archisodevice}" ]] && archisodevice="/dev/disk/by-label/${archisolabel}"
     if [[ -z "${cowfile_size}" ]]; then
-        cowfile_size="100"
-    else
-        cowfile_size=${cowfile_size/%}
+        cowfile_size="256M"
     fi
 
     if [[ -n "${cow_label}" ]]; then