[PATCH] auto setup network without netroot

[Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Current dracut network only will be setup when netroot is used. But there are
some cases we need network even without netroot. For example kdump will need
copy vmcore to remote machine via scp or nfs mount. OTOH, if we use dracut as
a recovery system the network is helpful even root is not a network device.

This implementation is based on the manually bring up method. Here add a kernel
cmdline argument rd.neednet. If rd.neednet is set dracut will bring up network
with ifup $INTERFACE -m. If netroot is used we still keep original behavior.

Signed-off-by: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 dracut.cmdline.7.xml                |    8 ++++++++
 modules.d/40network/net-genrules.sh |   20 ++++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

Index: dracut/modules.d/40network/net-genrules.sh
===================================================================
--- dracut.orig/modules.d/40network/net-genrules.sh
+++ dracut/modules.d/40network/net-genrules.sh
@@ -14,7 +14,7 @@ fix_bootif() {
 }
 
 # Don't continue if we don't need network
-[ -z "$netroot" ] && return;
+[ -z "$netroot" ] && ! getargbool 0 rd.neednet && return;
 
 # Write udev rules
 {
@@ -35,17 +35,29 @@ fix_bootif() {
     BOOTIF=$(getarg 'BOOTIF=')
     if [ -n "$BOOTIF" ] ; then
         BOOTIF=$(fix_bootif "$BOOTIF")
-        printf 'ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$BOOTIF"
+        if [ -n "$netroot" ]; then
+            printf 'ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$BOOTIF"
+        else
+            printf 'ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="%s", RUN+="/sbin/ifup $env{INTERFACE} -m"\n' "$BOOTIF"
+        fi
 
     # If we have to handle multiple interfaces, handle only them.
     elif [ -n "$IFACES" ] ; then
         for iface in $IFACES ; do
-            printf 'SUBSYSTEM=="net", ENV{INTERFACE}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$iface"
+            if [ -n "$netroot" ]; then
+                printf 'SUBSYSTEM=="net", ENV{INTERFACE}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$iface"
+            else
+                printf 'SUBSYSTEM=="net", ENV{INTERFACE}=="%s", RUN+="/sbin/ifup $env{INTERFACE} -m"\n' "$iface"
+            fi
         done
 
     # Default: We don't know the interface to use, handle all
     else
-        printf 'SUBSYSTEM=="net", RUN+="/sbin/ifup $env{INTERFACE}"\n'
+        if [ -n "$netroot" ]; then
+            printf 'SUBSYSTEM=="net", RUN+="/sbin/ifup $env{INTERFACE}"\n'
+        else
+            printf 'SUBSYSTEM=="net", RUN+="/sbin/ifup $env{INTERFACE} -m"\n'
+        fi
     fi
 
 } > /etc/udev/rules.d/60-net.rules
Index: dracut/dracut.cmdline.7.xml
===================================================================
--- dracut.orig/dracut.cmdline.7.xml
+++ dracut/dracut.cmdline.7.xml
@@ -507,6 +507,14 @@ Required if multiple ip= lines are used.
             <para>turn on/off biosdevname network interface renaming</para>
           </listitem>
         </varlistentry>
+        <varlistentry>
+          <term>
+            <envar>rd.neednet=</envar><replaceable>&lt;0|1&gt;</replaceable>
+          </term>
+          <listitem>
+            <para>boolean, bring up network even without netroot set</para>
+          </listitem>
+        </varlistentry>
       </variablelist>
     </refsect2>
     <refsect2>