Merge lp:~smoser/cloud-initramfs-tools/recursive into lp:cloud-initramfs-tools

[Scott Moser]

support for overlaying all mounts, rather than just '/'

This adds the ability to do "recursive" overlay, and enables that
by default.

It also adds 'swap=' parameter, which allows you to enable swap
partitions. The behavior previously was to disable all swap.

The overlayroot-chroot program is updated to incorporate the recurse
setting.

[lp:~smoser/cloud-initramfs-tools/recursive]

30. By Scott Moser on 2012-07-23

overlay-chroot: make sure you exit with number, not ''

=== modified file 'overlayroot/etc/overlayroot.conf'
--- overlayroot/etc/overlayroot.conf	2012-07-20 22:53:28 +0000
+++ overlayroot/etc/overlayroot.conf	2012-07-23 19:58:19 +0000
@@ -4,14 +4,18 @@
 #   1) edit the 'overlayroot' definition below
 #   2) reboot
 #
-# Supported parameters:
-#  * overlayroot="tmpfs"
+# Supported values:
+#  * overlayroot=tmpfs or overlayroot=tmpfs:PARAMETERS
 #    write all changes to a temporary (ram only) backing device
 #    A tmpfs mount will be created, and usable filesystem can
 #    grow to 1/2 available memory.
 #
-#    example:
+#    available parameters:
+#     * see COMMON PARAMETERS
+#
+#    examples:
 #     overlayroot=tmpfs
+#     overlayroot=tmpfs:swap=1
 #
 #  * overlayroot=DEVICE or overlayroot=device:PARAMETERS
 #    mount DEVICE as overlayfs and write changes there
@@ -29,6 +33,7 @@
 #       the directory under the filesystem to use for writes
 #       default is to use top level directory.  For example, use
 #       'dir=my-tests/run1' and later 'dir=my-tests/run2'
+#     * see COMMON PARAMETERS
 #
 #    examples:
 #      overlayroot=/dev/xvdb
@@ -60,6 +65,7 @@
 #     * dir: default: "/"
 #       the directory under the filesystem to use for writes.
 #       only really useful if you will re-use the mount later.
+#     * see COMMON PARAMETERS
 #       
 #    examples:
 #      crypt:mapname=mapper,pass=foo,fstype=ext4,mkfs=1,dev=vdb
@@ -70,6 +76,26 @@
 #    if set explicitly to 'disabled', or an empty string, then
 #    overlayroot will do nothing.
 #
+#
+# COMMON PARAMETERS:
+#   The following parameters are supported for each of overlayroot=
+#   values above.
+#   * swap: default: 0
+#     allowed values: 0, 1
+#     indicate if swap partitions should be allowed.  By default swap entries
+#     are removed from /etc/fstab to disable swap.
+#     Swap *files* are always disabled, independent of this setting.
+#
+#   * recurse: default: 1
+#     allowed values: 0, 1
+#     indicate if all mounts should be made read-only, or just /.
+#     if set to 1, then all filesystems will be mounted read-only.
+#     if set to 0, only root will be set to read-only, and changes
+#     to other filesystems will be permenant.  For example, if
+#     /home is on a separate partition from / and recurse set to 0
+#     then changes to /home will go through to the original device.
+#
+#
 # Notes:
 #  * you can pass the same 'overlayroot=' parameters on the kernel
 #    command line, and they will override any values set here.
 
=== modified file 'overlayroot/scripts/init-bottom/overlayroot'
--- overlayroot/scripts/init-bottom/overlayroot	2012-07-20 22:53:28 +0000
+++ overlayroot/scripts/init-bottom/overlayroot	2012-07-23 19:58:19 +0000
@@ -229,6 +229,56 @@
 	_RET_DIR="$dir"
 }
 
+overlayrootify_fstab() {
+	local input="$1" root_ro="${2:-/media/root-ro}"
+	local root_rw="${3:-/media/root-rw}" dir_prefix="${4:-/}"
+	local recurse=${5:-1} swap=${6:-0}
+	local hash="#"
+	local vfstypes=" proc sys tmpfs dev udev "
+	local spec file vfstype opts pass freq line ro_line
+	[ -f "$input" ] || return 1
+	while read spec file vfstype opts pass freq; do
+		line="$spec $file $vfstype $opts $pass $freq"
+		case ",$opts," in
+			*,ro,*) ro_opts="$opts";;
+			*) ro_opts="ro,${opts}";;
+		esac
+		ro_line="$spec ${root_ro}$file $vfstype ${ro_opts} $pass $freq"
+		if [ "${spec#${hash}}" != "$spec" ] ||
+		   [ -z "$freq" ]; then
+			# line has a comment in first field, or not 6 fields
+			echo "$line"
+		elif [ "${vfstypes# *${vfstype} }" != "${vfstypes}" ]; then
+			# this is a virtual filesystem, just let it through
+			echo "${line}"
+		elif [ "$vfstype" = "swap" ]; then
+			if [ "$swap" = "0" ]; then
+				# comment out swap lines
+				echo "#overlayroot:swap=${swap}#${line}"
+			elif [ "${spec#/}" != "${spec}" ] &&
+			     [ "${spec#/dev/}" = "${spec}" ]; then
+				# comment out swap files (spec starts with / and not in /dev)
+				echo "#overlayroot:swapfile#${line}"
+			else
+				echo "${line}"
+			fi
+		else
+			if [ "$recurse" != "0" ]; then
+				echo "$ro_line"
+			else
+				echo "$line"
+			fi
+			if [ "$file" = "/" ]; then
+				# write an entry for /
+				oline="overlayroot ${file} overlayfs "
+				oline="${oline}lowerdir=${root_ro}${file},"
+				oline="${oline}upperdir=${root_ro}${file} $pass $freq"
+				echo "$oline"
+			fi
+		fi
+	done < "$input"
+}
+
 
 # collect kernel parameter value into a config file
 kern_cfg="/tmp/${0##*/}.kernel-cmdline.cfg"
@@ -261,8 +311,13 @@
 done
 rm -f "$kern_cfg"
 
+opts=""
 case "${overlayroot:-disabled}" in
-	tmpfs) mode="tmpfs";;
+	tmpfs|tmpfs:*)
+		mode="tmpfs"
+		opts="${overlayroot#tmpfs}";
+		opts=${opts#:}
+		;;
 	/dev/*|device:*)
 		case "$overlayroot" in
 			/dev/*) opts="dev=${overlayroot}";;
@@ -274,9 +329,9 @@
 		device="$_RET_DEVICE"
 		dir_prefix="$_RET_DIR"
 		;;
-	crypt|crypt:*)
+	crypt:*)
 		mode="crypt"
-		t=${overlayroot#crypt}
+		opts=${overlayroot#crypt:}
 		crypto_setup "${t#:}" ||
 			fail "failed setup crypt for ${overlayroot}"
 		device="$_RET_DEVICE"
@@ -290,7 +345,16 @@
 		exit 0;;
 esac
 
-log_warn "configuring 'overlayroot=$overlayroot' per $used_desc"
+parse_string "$opts" "," _RET_common_
+swap=${_RET_common_swap:-0}
+recurse=${_RET_common_recurse:-1}
+
+[ "$swap" = "0" -o "$swap" = "1" ] ||
+	fail "invalid setting for swap: $swap. must be '0' or '1'"
+[ "$recurse" = "0" -o "$recurse" = "1" ] ||
+	fail "invalid setting for recurse: $recurse. must be '0' or '1'"
+
+log_warn "configuring overlayroot with mode=$mode opts='$opts' per $used_desc"
 
 # overlayroot_driver *could* be defined in one of the configs above
 # but we're not documenting that.
@@ -398,33 +462,22 @@
 # Remember we are still on the initramfs root fs here, so we have to work
 # on ${ROOTMNT}/etc/fstab. The original fstab is
 # ${ROOTMNT}${root_ro}/etc/fstab.
-root_type=$(awk '$1 == root { print $3 }' "root=$ROOT" /proc/mounts)
-root_options=$(awk '$1 == root { print $4 }' "root=$ROOT" /proc/mounts)
 cat <<EOF >${ROOTMNT}/etc/fstab
 #
 #  This fstab is in an overlayfs.  The real one can be found at
 #  ${root_ro}/etc/fstab
-#  The original entry for '/' and all swap files have been removed.  The new
-#  entry for the read-only the real root fs follows.  To permanently
-#  modify this (or any other file), you should change-root into a writable
-#  view of the underlying filesystem using:
+#  The original entry for '/' and other mounts have been updated to be placed
+#  under $root_ro.
+#  To permanently modify this (or any other file), you should change-root into
+#  a writable view of the underlying filesystem using:
 #      sudo overlayroot-chroot
 #
-
-${ROOT} ${root_ro} ${root_type} ${root_options} 0 0
-
-#
-#  remaining entries from the original ${root_ro}/etc/fstab follow.
-#
 EOF
+
 [ $? -eq 0 ] || log_fail "failed to modify /etc/fstab (step 1)"
-
-#comment out root and swap entries passing others through unmodified
-awk '{ 
-	if ($0 ~ /^#/ || ($2 != "/" && $3 != "swap") ) { print $0 }
-	else { printf("%s%s\n","#overlayroot#",$0); }
-	}' "${ROOTMNT}${root_ro}/etc/fstab" >> "${ROOTMNT}/etc/fstab" ||
-	log_fail "failed to modify etc/fstab (step 2)"
+overlayrootify_fstab ""${ROOTMNT}${root_ro}/etc/fstab"" "$root_ro" \
+	"$root_rw" "$dir_prefix" "$recurse" "$swap" >> "${ROOTMNT}/etc/fstab" ||
+	log_fail "failed to modify /etc/fstab (step 2)"
 
 msg="configured root with '$overlayroot' using ${overlayroot_driver} per"
 msg="$msg ${used_desc}"
 
=== modified file 'overlayroot/usr/sbin/overlayroot-chroot'
--- overlayroot/usr/sbin/overlayroot-chroot	2012-07-20 19:53:11 +0000
+++ overlayroot/usr/sbin/overlayroot-chroot	2012-07-23 19:58:19 +0000
@@ -18,6 +18,8 @@
 #    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 set -e
+set -f # disable path expansion
+REMOUNTS=""
 
 error() {
 	printf "ERROR: $@\n" 1>&2
@@ -44,23 +46,26 @@
 }
 
 clean_exit() {
-	local mounts="$1" rc="" d="" lowerdir=""
+	local mounts="$1" rc=0 d="" lowerdir="" mp=""
 	for d in ${mounts}; do
 		if mountpoint ${d} >/dev/null; then
 			umount ${d} || rc=1
 		fi
 	done
-	get_lowerdir
-	lowerdir=${_RET}
-	if ! mount -o remount,ro "${lowerdir}"; then
-		error "Note that [${lowerdir}] is still mounted read/write"
-	fi
-	[ "$2" = "return" ] && return ${rc} || exit "${rc}"
+	for mp in $REMOUNTS; do
+		mount -o remount,ro "${mp}" ||
+			error "Note that [${mp}] is still mounted read/write"
+	done
+	[ "$2" = "return" ] && return ${rc} || exit ${rc}
 }
 
 # Try to find the overlayroot filesystem
 get_lowerdir
 lowerdir=${_RET}
+
+recurse_mps=$(awk '$1 ~ /^\/dev\// && $2 ~ starts { print $2 }' \
+	starts="^$lowerdir/" /proc/mounts)
+
 mounts=
 for d in proc run sys; do
 	if ! mountpoint "${lowerdir}/${d}" >/dev/null; then
@@ -71,8 +76,11 @@
 done
 
 # Remount with read/write
-mount -o remount,rw "${lowerdir}" ||
-   fail "Unable to remount [${lowerdir}] writable"
+for mp in "$lowerdir" $recurse_mps; do
+	mount -o remount,rw "${mp}" &&
+		REMOUNTS="$mp $REMOUNTS" ||
+		fail "Unable to remount [$mp] writable"
+done
 info "Chrooting into [${lowerdir}]"
 chroot ${lowerdir} "$@"