On Wed, 27 Feb 2008, Luke Yelavich wrote:
> Attached is a patch to allow an initramfs to use a root filesystem as a
> loop device, on top of another file system. A good example and use of
> this code is for Ubuntu's Windows installer, which creates a loopback
> filesystem on top of the Windows NTFS partition. The Windows partition
> is mounted, then the loopback filesystem is mounted from the Windows
> partition. The patch applies against git head.
ack cool,
see specific critics below.
> diff -urN initramfs-tools/init initramfs-tools.new/init
> --- initramfs-tools/init 2008-02-26 10:36:10.347676705 +1100
> +++ initramfs-tools.new/init 2008-02-26 13:50:26.459676705 +1100
> @@ -85,6 +85,15 @@
> ;;
> esac
> ;;
> + loop=*)
> + LOOP="${x#loop=}"
> + ;;
> + loopflags=*)
> + LOOPFLAGS="-o ${x#loopflags=}"
> + ;;
> + loopfstype=*)
> + LOOPFSTYPE="${x#loopfstype=}"
> + ;;
> nfsroot=*)
> NFSROOT="${x#nfsroot=}"
> ;;
don't see them in kernel-parameter.txt but this namespace seems sane,
so ack from me.
> diff -urN initramfs-tools/initramfs-tools.8
> initramfs-tools.new/initramfs-tools.8
> --- initramfs-tools/initramfs-tools.8 2008-02-26 13:48:37.435676705 +1100
> +++ initramfs-tools.new/initramfs-tools.8 2008-02-26 13:49:26.251676705
> +1100
<snipp manpage diff>
ok too.
> diff -urN initramfs-tools/scripts/local initramfs-tools.new/scripts/local
> --- initramfs-tools/scripts/local 2008-02-26 13:48:37.423676705 +1100
> +++ initramfs-tools.new/scripts/local 2008-02-26 13:49:26.239676705 +1100
> @@ -101,7 +101,8 @@
> run_scripts /scripts/local-premount
> [ "$quiet" != "y" ] && log_end_msg
>
> - if [ "${readonly}" = "y" ]; then
> + if [ ${readonly} = y ] && \
> + ([ -z "$LOOP" ] || [ "${FSTYPE#ntfs}" = "$FSTYPE" ]); then
> roflag=-r
> else
> roflag=-w
hmm at first sight i found a bit strange that you use not a different boot
method for the loop fs stuff, like setting BOOT=loop if loop bootarg is
given and then just having scripts/loop. but on the contrary i agree that
it is on a local fs almost identical path and would lead otherwise to
code duplication of the local boot scripts and thus fine with me.
> @@ -114,6 +115,43 @@
> # Mount root
> mount ${roflag} -t ${FSTYPE} ${ROOTFLAGS} ${ROOT} ${rootmnt}
>
> + if [ "$LOOP" ]; then
> + mkdir -p /host
> + mount -o move ${rootmnt} /host
> +
> + while [ ! -e "/host/${LOOP#/}" ]; do
> + panic "ALERT! /host/${LOOP#/} does not exist.
> Dropping to a shell!"
> + done
that check should go up and check that aboves mount doesn't fail,
otherwise i don't see a possibility of that happening.
> +
> + # Get the loop filesystem type if not set
> + if [ -z "${LOOPFSTYPE}" ]; then
> + eval $(fstype < "/host/${LOOP#/}")
> + else
> + FSTYPE="${LOOPFSTYPE}"
> + fi
> + if [ "$FSTYPE" = "unknown" ] && [ -x /lib/udev/vol_id ]; then
> + FSTYPE=$(/lib/udev/vol_id -t "/host/${LOOP#/}")
> + [ -z "$FSTYPE" ] && FSTYPE="unknown"
> + fi
no thanks
duplication use get_fstype
> +
> + if [ ${readonly} = y ]; then
> + roflag=-r
> + else
> + roflag=-w
> + fi
> +
> + # FIXME This has no error checking
> + modprobe loop
> + modprobe ${FSTYPE}
> +
> + # FIXME This has no error checking
> + mount ${roflag} -o loop -t ${FSTYPE} ${LOOPFLAGS}
> "/host/${LOOP#/}" ${rootmnt}
yep that was the FIXME i was talking about above.
please add mount returnvalue check here too.
afais klibc mount returns sensible error codes.
> +
> + if [ -d ${rootmnt}/host ]; then
> + mount -o move /host ${rootmnt}/host
> + fi
> + fi
> +
> [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/local-bottom"
> run_scripts /scripts/local-bottom
> [ "$quiet" != "y" ] && log_end_msg
thanks for the submission.
--
maks
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