aufs: add basic support to AUFS2, requires kernel with aufs module or built-in

ChangeLog

@@ -5,6 +5,10 @@
 # Distributed under the GPL v2
 # $Id$
 
+  28 Aug 2011; Fabio Erculiani <lxnay@gentoo.org> defaults/initrd.scripts,
+  defaults/linuxrc, doc/genkernel.8.txt:
+  Add basic support to AUFS2, requires kernel with aufs module or built-in
+
   16 Aug 2011; Fabio Erculiani <lxnay@gentoo.org> gen_compile.sh:
   gen_compile: correct MAKEOPTS usage on utils task
 

defaults/initrd.scripts

@@ -924,6 +924,13 @@ sdelay() {
 	then
 		good_msg "Waiting ${SDELAY} seconds..."
 		sleep ${SDELAY}
+	elif [ "${CDROOT}" = '1' ]
+	then
+		# many CD/DVD drives require extra sleep, especially when
+		# connected via USB. Many people reported that 1 second sleep
+		# is not enough on their notebooks, that's why sleep 3, when booting
+		# off a livecd is a better default.
+		sleep 3
 	else
 		good_msg 'Hint: Use parameter scandelay[=seconds] if you need waiting here'
 	fi
@@ -1082,6 +1089,34 @@ getdvhoff() {
 	echo $(( $(hexdump -n 4 -s $((316 + 12 * $2)) -e '"%i"' $1) * 512))
 }
 
+setup_squashfs_aufs() {
+	(
+	# Setup aufs directories and vars
+	local overlay=/mnt/overlay
+	local static=/mnt/livecd
+
+	for i in "${overlay}" "${static}"; do
+		[ ! -d "${i}" ] && mkdir -p "${i}"
+	done
+	good_msg "Loading aufs"
+	modprobe aufs > /dev/null 2>&1
+
+	cd "${NEW_ROOT}"
+	mount -t squashfs -o loop,ro "mnt/cdrom${LOOPEXT}${LOOP}" "${static}"
+	mount -t tmpfs none "${overlay}"
+	mount -t aufs -o br:${overlay}:${static} aufs "${NEW_ROOT}"
+
+	[ ! -d "${NEW_ROOT}${overlay}" ] && mkdir -p "${NEW_ROOT}${overlay}"
+	[ ! -d "${NEW_ROOT}${static}" ] && mkdir -p "${NEW_ROOT}${static}"
+	echo "aufs / aufs defaults 0 0" > "${NEW_ROOT}"/etc/fstab
+	for i in "${overlay}" "${static}"; do mount --move "${i}" "${NEW_ROOT}${i}"; done
+
+	# have handy /mnt/cdrom as well
+	[ ! -d "${NEW_ROOT}/mnt/cdrom" ] && mkdir -p "${NEW_ROOT}/mnt/cdrom"
+	mount --bind mnt/cdrom "${NEW_ROOT}/mnt/cdrom"
+	)
+}
+
 setup_unionfs() {
 	local rw_dir=$1
 	local ro_dir=$2

defaults/linuxrc

@@ -213,6 +213,9 @@ do
 		keymap\=*)
 			keymap=`parse_opt "${x}"`
 		;;
+		aufs)
+			USE_AUFS_NORMAL=1
+		;;
 		unionfs)
 			if [ ! -x /sbin/unionfs ]
 			then
@@ -569,9 +572,14 @@ then
 			FS_LOCATION='mnt/livecd'
 		elif [ "${LOOPTYPE}" = 'squashfs' ]
 		then
-			good_msg 'Mounting squashfs filesystem'
-			mount -t squashfs -o loop,ro "${NEW_ROOT}/mnt/cdrom/${LOOPEXT}${LOOP}" "${NEW_ROOT}/mnt/livecd"
-			test_success 'Mount filesystem'
+			if [ "${USE_AUFS_NORMAL}" != '1' ]; then
+				good_msg 'Mounting squashfs filesystem'
+				mount -t squashfs -o loop,ro "${NEW_ROOT}/mnt/cdrom/${LOOPEXT}${LOOP}" "${NEW_ROOT}/mnt/livecd"
+			else
+				good_msg 'Mounting squashfs & aufs filesystems'
+				setup_squashfs_aufs
+				test_success 'Mount filesystem'
+			fi
 			FS_LOCATION='mnt/livecd'
 		elif [ "${LOOPTYPE}" = 'gcloop' ]
 		then
@@ -636,7 +644,7 @@ then
 	then
 		setup_unionfs ${NEW_ROOT} ${NEW_ROOT}/${FS_LOCATION}
 		CHROOT=/union
-	else
+	elif [ "${USE_AUFS_NORMAL}" != '1' ]; then
 	
 	good_msg "Copying read-write image contents to tmpfs"
 	# Copy over stuff that should be writable

doc/genkernel.8.txt

@@ -511,6 +511,9 @@ which the ramdisk scripts would recognize.
 *nounionfs*::
     Enables/disables UnionFS.
 
+*aufs*::
+    Enables support for AUFS2 (if available in the kernel).
+
 *real_rootflags*=<...>::
     Additional flags to mount the real root system with.
     For example *real_rootflags*=noatime would make "-o ro,noatime".