[Buildroot] [PATCH v2] system: Fix for NFS booting with interface config via DHCP

[Arnout Vandecappelle <arnout@mind.be>]

On 09-11-15 23:16, Trent Piepho wrote:
> Configuring the network interface with DHCP via
> /etc/network/interfaces generally does not work when NFS booting.  The
> DHCP configuration will initially bring the interface down and system
> then hangs at that point as the root filesystem is no longer
> accessable.  See bug 4709.
> 
> This adds a script to be run via a pre-up line in
> /etc/network/interfaces.  It checks for a NFS root filesystem and if
> the interface to be configured is used for access to the NFS server.
> If this is the case, then it returns a failure code so that ifup will
> not configure the interface.  This works for DHCP and another config
> methods (static, bootp, etc.).  This system does detect if the
> interface to be configured isn't the one used for NFS and doesn't skip
> it when that is the case.
> 
> NFS filesystems that aren't the root fs aren't considered.
> 
> Signed-off-by: Trent Piepho <tpiepho@kymetacorp.com>

Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

 I checked that the addr= appears in /proc/mounts since at least 2.6.17.

 IMHO this is still for 2015.11.


 Regards,
 Arnout


> ---
>  package/skeleton/nfs_check   | 20 ++++++++++++++++++++
>  package/skeleton/skeleton.mk |  3 +++
>  2 files changed, 23 insertions(+)
>  create mode 100755 package/skeleton/nfs_check
> 
> diff --git a/package/skeleton/nfs_check b/package/skeleton/nfs_check
> new file mode 100755
> index 0000000..dfa0cbf
> --- /dev/null
> +++ b/package/skeleton/nfs_check
> @@ -0,0 +1,20 @@
> +#!/bin/sh
> +
> +# This allows NFS booting to work while also being able to configure
> +# the network interface via DHCP when not NFS booting.  Otherwise, a
> +# NFS booted system will likely hang during DHCP configuration.
> +
> +# Attempting to configure the network interface used for NFS will
> +# initially bring that network down.  Since the root filesystem is
> +# accessed over this network, the system hangs.
> +
> +# This script is run by ifup and will attempt to detect if a NFS root
> +# mount uses the interface to be configured (IFACE), and if so does
> +# not configure it.  This should allow the same build to be disk/flash
> +# booted or NFS booted.
> +
> +nfsip=`sed -n '/^[^ ]*:.* \/ nfs.*[ ,]addr=\([0-9.]\+\).*/s//\1/p' /proc/mounts`
> +if [ -n "$nfsip" ] && ip route get to "$nfsip" | grep -q "dev $IFACE"; then
> +	echo Skipping $IFACE, used for NFS from $nfsip
> +	exit 1
> +fi
> diff --git a/package/skeleton/skeleton.mk b/package/skeleton/skeleton.mk
> index d1b797d..0cab8a1 100644
> --- a/package/skeleton/skeleton.mk
> +++ b/package/skeleton/skeleton.mk
> @@ -89,8 +89,11 @@ define SET_NETWORK_DHCP
>  		echo ;                                               \
>  		echo "auto $(NETWORK_DHCP_IFACE)";                   \
>  		echo "iface $(NETWORK_DHCP_IFACE) inet dhcp";        \
> +		echo "  pre-up /etc/network/nfs_check";              \
>  		echo "	wait-delay 15";                              \
>  	) >> $(TARGET_DIR)/etc/network/interfaces
> +	$(INSTALL) -m 0755 -D $(SKELETON_PKGDIR)/nfs_check \
> +		$(TARGET_DIR)/etc/network/nfs_check
>  endef
>  endif
>  
> 


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
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