allow ifup bring up network manually even without netroot

For kdump we need scp vmcore to remote machine, the nic to be used is
not limited to netroot one. we need a feature for manually bringing up
 network interface. Also it is useful for emergency shell with
ssh-client for recovery or test purpose

I implement this by adding one argument to ifup script, user can use
`/sbin/ifup eth0 -m` to bring up eth0, note ifup will regard it a
manual operation for the nic specified in 1st argument if there's
the 2nd argument.

If same nic is used for netroot the 2nd argument will be ignored,
in this case we will leave netroot bring up it automatically to
avoid side effect. And in this case hooks such as kdump will need to
execute after netroot mounted.

`ifup eth0 -m` will create /tmp/net.eth0.manualup stamp file,
later dhclient-script can check this and pass $2 to netroot,
then netroot script will bring eth0 up

Thanks for comments and suggestions from David Dillow.

Signed-off-by: Dave Young <dyoung@redhat.com>

modules.d/40network/dhclient-script

@@ -76,7 +76,13 @@ case $reason in
             echo "$line"
         done >/tmp/dhclient.$netif.dhcpopts
         echo online > /sys/class/net/$netif/uevent
+
+        if [ -e /tmp/net.$netif.manualup ]; then
+            /sbin/netroot $netif -m
+            rm -f /tmp/net.$netif.manualup
+        else
             initqueue --onetime --name netroot-$netif netroot $netif
+        fi
         ;;
     *) echo "dhcp: $reason";;
 esac

modules.d/40network/ifup

@@ -5,9 +5,54 @@
 # We don't need to check for ip= errors here, that is handled by the
 # cmdline parser script
 #
+# without $2 means this is for real netroot case
+# or it is for manually bring up network ie. for kdump scp vmcore
 PATH=/usr/sbin:/usr/bin:/sbin:/bin
 
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
+export PS4="ifup.$1.$$ + "
+exec >>/run/initramfs/loginit.pipe 2>>/run/initramfs/loginit.pipe
+type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
+
+# Huh? No $1?
+[ -z "$1" ] && exit 1
+
+# $netif reads easier than $1
+netif=$1
+
+# enslave this interface to bond?
+if [ -e /tmp/bond.info ]; then
+    . /tmp/bond.info
+    for slave in $bondslaves ; do
+        if [ "$netif" = "$slave" ] ; then
+            netif=$bondname
+        fi
+    done
+fi
+
+# bridge this interface?
+if [ -e /tmp/bridge.info ]; then
+    . /tmp/bridge.info
+    if [ "$netif" = "$ethname" ]; then
+        if [ "$netif" = "$bondname" ] && [ -n "$DO_BOND_SETUP" ] ; then
+            : # We need to really setup bond (recursive call)
+        else
+            netif="$bridgename"
+        fi
+    fi
+fi
+
+# bail immediately if the interface is already up
+# or we don't need the network
+[ -f "/tmp/net.$netif.up" ] && exit 0
+[ -f "/tmp/root.info" ] || exit 0
+. /tmp/root.info
+
+# disable manual ifup while netroot is set for simplifying our logic
+# in netroot case we prefer netroot to bringup $netif automaticlly
+[ -n "$2" ] && [ -z "$netroot" ] && manualup="$2"
+[ -z "$netroot" ] && [ -z "$manualup" ] && exit 0
+[ -n "$manualup" ] && >/tmp/net.$netif.manualup
 
 # Run dhclient
 do_dhcp() {
@@ -50,7 +95,11 @@ do_ipv6auto() {
 
 
     echo online > /sys/class/net/$netif/uevent
+    if [ -n "$manualup" ]; then
+        /sbin/netroot $netif -m
+    else
         initqueue --onetime --name netroot-$netif netroot $netif
+    fi
 }
 
 # Handle static ip configuration
@@ -77,47 +126,12 @@ do_static() {
     fi >> /tmp/net.$netif.resolv.conf
 
     echo online > /sys/class/net/$netif/uevent
-    initqueue --onetime --name netroot-$netif netroot $netif
-}
-
-export PS4="ifup.$1.$$ + "
-exec >>/run/initramfs/loginit.pipe 2>>/run/initramfs/loginit.pipe
-type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
-
-# Huh? No $1?
-[ -z "$1" ] && exit 1
-
-# $netif reads easier than $1
-netif=$1
-
-# enslave this interface to bond?
-if [ -e /tmp/bond.info ]; then
-    . /tmp/bond.info
-    for slave in $bondslaves ; do
-        if [ "$netif" = "$slave" ] ; then
-            netif=$bondname
-        fi
-    done
-fi
-
-# bridge this interface?
-if [ -e /tmp/bridge.info ]; then
-    . /tmp/bridge.info
-    if [ "$netif" = "$ethname" ]; then
-        if [ "$netif" = "$bondname" ] && [ -n "$DO_BOND_SETUP" ] ; then
-            : # We need to really setup bond (recursive call)
+    if [ -n "$manualup" ]; then
+        /sbin/netroot $netif -m
     else
-            netif="$bridgename"
-        fi
-    fi
+        initqueue --onetime --name netroot-$netif netroot $netif
     fi
-
-# bail immediately if the interface is already up
-# or we don't need the network
-[ -f "/tmp/net.$netif.up" ] && exit 0
-[ -f "/tmp/root.info" ] || exit 0
-. /tmp/root.info
-[ -z "$netroot" ] && exit 0
+}
 
 # loopback is always handled the same way
 if [ "$netif" = "lo" ] ; then
@@ -228,5 +242,4 @@ for p in $(getargs ip=); do
     esac
     break
 done
-
 exit 0

modules.d/40network/netroot

@@ -3,7 +3,6 @@
 # ex: ts=8 sw=4 sts=4 et filetype=sh
 
 PATH=/usr/sbin:/usr/bin:/sbin:/bin
-
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 
 # Huh? Empty $1?
@@ -12,12 +11,16 @@ type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 # Huh? No interface config?
 [ ! -e /tmp/net.$1.up ] && exit 1
 
-# There's no sense in doing something if no (net)root info is available
+# [ ! -z $2 ] means this is for manually bringing up network
+# instead of real netroot; If It's called without $2, then there's
+# no sense in doing something if no (net)root info is available
 # or root is already there
 [ -e /tmp/root.info ] || exit 1
 . /tmp/root.info
+if [ -z "$2" ]; then
     [ -d $NEWROOT/proc ] && exit 0
     [ -z "$netroot" ] && exit 1
+fi
 
 # Let's see if we have to wait for other interfaces
 # Note: exit works just fine, since the last interface to be
@@ -31,8 +34,13 @@ done
 netif=$1
 [ -e "/tmp/net.bootdev" ] && read netif < /tmp/net.bootdev
 
+if [ -e /tmp/net.$netif.manualup ]; then
+    rm -f /tmp/net.$netif.manualup
+fi
+
 # Figure out the handler for root=dhcp by recalling all netroot cmdline
-# handlers
+# handlers when this is not called from manually network bringing up.
+if [ -z "$2" ]; then
     if [ "$netroot" = "dhcp" ] || [ "$netroot" = "dhcp6" ] ; then
         # Unset root so we can check later
         unset root
@@ -69,6 +77,7 @@ handler=$(command -v ${handler}root)
     if [ -z "$netroot" ] || [ ! -e "$handler" ] ; then
         die "No handler for netroot type '$netroot'"
     fi
+fi
 
 # We're here, so we can assume that upping interfaces is now ok
 [ -z "$IFACES" ] && IFACES="$netif"
@@ -122,6 +131,9 @@ if [ -n "$dest" ] && ! arping -q -f -w 60 -I $netif $dest ; then
     dinfo "Resolving $dest via ARP on $netif failed"
 fi
 
+# exit in case manually bring up network
+[ -n "$2" ] && exit 0
+
 # Source netroot hooks before we start the handler
 source_all $hookdir/netroot