From dae040172f5ffdc8daf602c2482c4dac598fd1bb Mon Sep 17 00:00:00 2001
From: Jonathan Bauer
Date: Wed, 4 Sep 2019 10:55:36 +0200
Subject: [dnbd3-rootfs] add kernel qcow2 loop module build

---
 builder/modules.d/dnbd3-rootfs/helper/build.inc | 51 ++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 2 deletions(-)

diff --git a/builder/modules.d/dnbd3-rootfs/helper/build.inc b/builder/modules.d/dnbd3-rootfs/helper/build.inc
index 03c6b222..0a7d7a8c 100644
--- a/builder/modules.d/dnbd3-rootfs/helper/build.inc
+++ b/builder/modules.d/dnbd3-rootfs/helper/build.inc
@@ -45,7 +45,15 @@ initialize_components() {
         fi
     fi
     if [ -z "$qcow_handler" ] || [ "$qcow_handler" = "kernel" ]; then
-        # TODO check if the given kernel supports it, bail otherwise
+        if [ ! -f "${kernel_headers}/drivers/block/loop/loop.ko " ] \
+            || [ ! -f "${kernel_headers}/drivers/block/loop/loop_file_fmt_qcow.ko " ] \
+            || [ ! -f "${kernel_headers}/drivers/block/loop/loop_file_fmt_raw.ko " ]; then
+            logging.info "Could not find loop kernel modules, building them..."
+            if ! build_compile_kernel_qcow "$kernel_headers"; then
+                logging.error "Failed to build qcow loop kernel modules."
+                return 1
+            fi
+        fi
         if [ ! -f "${_deps_base_dir}/kernel-qcow2-util-linux/losetup" ]; then
             logging.info "Could not find losetup with qcow2 support, building it..."
             if ! build_compile_losetup_qcow "${_deps_base_dir}/kernel-qcow2-util-linux"; then
@@ -188,7 +196,46 @@ build_clean_dnbd3() {
     rm --recursive --force "$1/build"
     return $?
 }
-# needs autopoint bison automake libtool
+build_compile_kernel_qcow() {
+    pushd "$1"
+    # https://lab.ks.uni-freiburg.de/projects/kernel-qcow2/wiki
+    if [ -z "$kernel_headers" ]; then
+        logging.error "Kernel header directory not set, ignoring."
+        return 1
+    fi
+    mkdir -p "${kernel_headers}/drivers/block/loop"
+    for _file in \
+        include/uapi/linux/loop.h \
+        drivers/block/Kconfig \
+        drivers/block/loop/loop_main.h \
+        drivers/block/loop/loop_file_fmt.h \
+        drivers/block/loop/Kconfig; do
+            cp -f "${_file}" "${kernel_headers}/${_file}"
+    done
+    (
+        set -o errexit
+        make -C "$kernel_headers" CONFIG_BLK_DEV_LOOP=m \
+            M=$(pwd)/drivers/block/loop loop.ko
+        make -C "$kernel_headers" CONFIG_BLK_DEV_LOOP_FILE_FMT_RAW=m \
+            M=$(pwd)/drivers/block/loop loop_file_fmt_raw.ko
+        make -C "$kernel_headers" CONFIG_BLK_DEV_LOOP_FILE_FMT_QCOW=m \
+            M=$(pwd)/drivers/block/loop loop_file_fmt_qcow.ko
+    )
+    local ret=$?
+    popd
+    return $ret
+}
+build_clean_kernel_qcow() {
+    if [ -z "$kernel_headers" ]; then
+        logging.error "Kernel header directory not set, ignoring."
+        return 1
+    fi
+    pushd "$kernel_headers"
+    make -C "$kernel_headers" M=$(pwd)/drivers/block/loop clean
+    local ret=$?
+    popd
+    return $ret
+}
 build_compile_losetup_qcow() {
     pushd "$1"
     (
-- 
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