Bug#782641: initramfs-tools: nfs booting requires /usr to be present on the nfs root filesystem

[Salvatore Bonaccorso <carnil@debian.org>]

Hi,

On Wed, Apr 15, 2015 at 03:01:44PM +0100, fc3452-00 wrote:
> Package: initramfs-tools
> Version: 0.120
> Severity: normal
> 
> Dear Maintainer,
> 
> Problem occurs when attempting to do an nfs network boot with no /usr directory
> present on the nfs root partition.
> 
> At https://www.debian.org/releases/jessie/i386/apcs02.html.en it says that
> /etc, /bin, /sbin, /lib & /dev must be present on the root partition in order
> to boot.
> 
> But in the script /usr/share/initramfs-tools/scripts/nfs there is:
> 
>         # loop until nfsmount succeeds
>         nfs_mount_root_impl
>         nfs_retry_count=0
>         while [ ${nfs_retry_count} -lt ${delay} ] \
>                 && ! chroot "${rootmnt}" test -x "${init}" ; do
>                 [ "$quiet" != "y" ] && log_begin_msg "Retrying nfs mount"
>                 /bin/sleep 1
>                 nfs_mount_root_impl
>                 nfs_retry_count=$(( ${nfs_retry_count} + 1 ))
>                 [ "$quiet" != "y" ] && log_end_msg
>         done
> 
> which attempts to execute /usr/bin/test immediately after mounting the root
> partition and before mounting any of the filesystems in /etc/fstab. This fails
> if your are trying to mount /usr from another filesystem by using an entry in
> /etc/fstab. The script could be modified to use the shell built-in "test"
> command by changing the line
> 
>                 && ! chroot "${rootmnt}" test -x "${init}" ; do
> 
> to
> 
>                 && ! chroot "${rootmnt}" sh -c "[ -x \"${init}\" ]" ; do
> 
> which enables the system to boot when /usr is not present.

Untested: One other option might be to move the validate_init()
wrapper from init to scripts/functions and use that from there as well
in scripts/nfs.

Regards,
Salvatore