Comment 12 for bug 1423796

After making my system work again, which took a while since most live media and even the installer don't support LVM cache, I had it working for writeback on my system with the following.

/etc/initramfs-tools/hooks/lvm2_cache
{{{
#!/bin/sh

PREREQ="lvm2"

prereqs()
{
    echo "$PREREQ"
}

case $1 in
prereqs)
    prereqs
    exit 0
    ;;
esac

if [ ! -x /sbin/lvm ]; then
    exit 0
fi

. /usr/share/initramfs-tools/hook-functions

copy_exec /usr/sbin/cache_check
copy_exec /usr/sbin/cache_dump
copy_exec /usr/sbin/cache_metadata_size
copy_exec /usr/sbin/cache_repair
copy_exec /usr/sbin/cache_restore

for x in dm_cache_cleaner dm_cache_smq dm_cache dm_persistent_data dm_bio_prison
do
    manual_add_modules ${x}
done
}}}