Handle module alias properly

Some modules (like ext4) provide aliases by which the modules
can be accessed, too. But when using aliases directly dracut
fails to include the correct module. So translate the alias
into the correct module name before checking the module.

References: bnc#886839

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Thomas Renninger <trenn@suse.de>

dracut-functions.sh

@@ -1689,6 +1689,13 @@ instmods() {
             --*) _mpargs+=" $_mod" ;;
             *)
                 _mod=${_mod##*/}
+                # Check for aliased modules
+                _modalias=$(modinfo -k $kernel -F filename $_mod 2> /dev/null)
+                _modalias=${_modalias%.ko}
+                if [ "${_modalias##*/}" != "$_mod" ] ; then
+                    _mod=${_modalias##*/}
+                fi
+
                 # if we are already installed, skip this module and go on
                 # to the next one.
                 if [[ $DRACUT_KERNEL_LAZY_HASHDIR ]] && \