If not set, nothing is changed in current behaviour.
Since dm-snapshot allows to use as "COW" a file with any size,
without caring about the the size of "origin", we can avoid creating a
"COW" file of the same size as the "origin". This is really useful,
when using as cow_device= a filesystem that is VFAT where sparse files
are not supported, so if root-image.fs is 1000M, passing cowfile_size=25%
will create a root-image.cow of 250M instead of 1000M.
---
README | 5 +++++
archiso/initcpio/hooks/archiso | 10 ++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/README b/README
index ce8d355..c33f444 100644
--- a/README
+++ b/README
@@ -65,6 +65,11 @@ INDEX
Size is in bytes (suffix with "k", "m" and "g") or
in percentage of available RAM.
Default: "75%"
+* cowfile_size= Set the size for all files to be used as COW (dm-snapshot),
+ in percentage of the ro-device.fs file. This is mostly useful
+ when cow_device= is used and filesystem does not support
+ sparse files (ie VFAT).
+ Default: "100%"
* copytoram_size= Set the size of tmpfs. This space is used for
copy of all SquashFS images used, if copytoram=y.
Size is in bytes (suffix with "k", "m" and "g") or
diff --git a/archiso/initcpio/hooks/archiso b/archiso/initcpio/hooks/archiso
index 5b94743..491ed2f 100644
--- a/archiso/initcpio/hooks/archiso
+++ b/archiso/initcpio/hooks/archiso
@@ -11,13 +11,14 @@ _mnt_fs() {
ro_dev=$(losetup --find --show --read-only "${img}")
echo ${ro_dev} >> /run/archiso/used_block_devices
ro_dev_size=$(blockdev --getsz ${ro_dev})
+ rw_dev_size=$((ro_dev_size*cowfile_size/100))
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}/${img_name}.cow" count=0 seek=${ro_dev_size} &> /dev/null
+ dd of="/run/archiso/cowspace/${cow_directory}/${img_name}.cow" count=0 seek=${rw_dev_size} &> /dev/null
fi
else
if [[ -f "/run/archiso/cowspace/${cow_directory}/${img_name}.cow" ]]; then
@@ -25,7 +26,7 @@ _mnt_fs() {
rm -f "/run/archiso/cowspace/${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}/${img_name}.cow" count=0 seek=${ro_dev_size} &> /dev/null
+ dd of="/run/archiso/cowspace/${cow_directory}/${img_name}.cow" count=0 seek=${rw_dev_size} &> /dev/null
fi
rw_dev=$(losetup --find --show "/run/archiso/cowspace/${cow_directory}/${img_name}.cow")
@@ -101,6 +102,11 @@ run_hook() {
[[ -z "${archisobasedir}" ]] && archisobasedir="arch"
[[ -z "${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/%}
+ fi
if [[ -z "${aitab}" ]]; then
aitab="/run/archiso/bootmnt/${archisobasedir}/aitab"
--
1.7.12.2