#!/bin/bash
# /usr/lib/initcpio/install/usr_file
build() {
    add_binary findmnt
    add_runscript
}
help() {
    cat <<HELPEOF
This provides a support for mounting /usr via a late running hook. No
configuration is needed, as the mount options will be pulled directly from the
fstab on the real root device.
HELPEOF
}
# vim: set ft=sh ts=4 sw=4 et:

#!/usr/bin/ash
# /usr/lib/initcpio/hooks/usr_file
run_latehook() {
    local realtab=/new_root/etc/fstab
    if [ -f "$realtab" ]; then
        if usr_source=$(findmnt -snero source --tab-file="$realtab" /usr); then
            mountopts=$(findmnt -snero options --tab-file="$realtab" /usr)
#            fsck_device "$usr_source"
            msg ":: mounting '$usr_source' on /usr"
#            mount "$usr_source" /new_root/usr -o "$mountopts"
            mount /new_root"$usr_source" /new_root/usr -o "$mountopts"
        fi
    fi
}
# vim: set ft=sh ts=4 sw=4 et:

#!/bin/sh
# /usr/local/sbin/fsck.squashfs
exit 0

#
# /etc/rc.d/functions.d/usr_file
#
NETFS=$NETFS",squashfs"

/usbUsr.sfs   /usr   squashfs   ro   0 0

MODULES="squashfs"
...
HOOKS="... usr_file filesystems ..."