Merge lp:~mvo/ubuntu/wily/initramfs-tools-ubuntu-core/new-and-old into lp:ubuntu/wily/initramfs-tools-ubuntu-core

[Michael Vogt]

This branch adds support for initramfs-tools in snappy to mount the new squashfs/snapfs based os and kernel snaps. It also keeps compatibility with the old snappy_ab partition layout so that we can have a smooth transition and easier testing.

[lp:~mvo/ubuntu/wily/initramfs-tools-ubuntu-core/new-and-old]

32. By Michael Vogt on 2015-10-19

hooks/ubuntu-core-rootfs: ensure squashfs module is part of the initramfs

33. By Michael Vogt on 2015-10-19

scripts/ubuntu-core-rootfs: no need for manual insmod, system will figure it out

[Michael Vogt (mvo)]

Thanks a bunch Ogra for your irc suggestions that lead to r32 and r33!

[lp:~mvo/ubuntu/wily/initramfs-tools-ubuntu-core/new-and-old]

34. By Michael Vogt on 2015-10-19

scripts/ubuntu-core-rootfs: do not hardcode LABEL=writable (thanks ogra!

[Oliver Grawert (ogra)]

there is one line that makes me itch a bit ....
after we mount $rootmnt from $writable_mnt we move $writable_mnt underneath $rootmnt, so we are effectively pulling out the floor under ourselves.
while i'm not sure what the implications of this actually are (since run-init makes everything above $rootmnt invisible anyway once we switch to the real root) I wonder if we shouldnt use --bind instead of --move (thats line 197 below)

mount --move "$writable_mnt" "${rootmnt}/writable"

[lp:~mvo/ubuntu/wily/initramfs-tools-ubuntu-core/new-and-old]

35. By Michael Vogt on 2015-10-21

fix label, re-add insmod of squashfs

36. By Michael Vogt on 2015-10-21

remove debug entry

[Timo Jyrinki (timo-jyrinki)]

Please resubmit to xenial.

review: Needs Resubmitting

=== modified file 'hooks/ubuntu-core-rootfs'
--- hooks/ubuntu-core-rootfs	2015-02-25 10:05:57 +0000
+++ hooks/ubuntu-core-rootfs	2015-10-21 13:53:20 +0000
@@ -22,3 +22,4 @@
 copy_exec /bin/chown
 copy_exec /sbin/findfs
 copy_exec /sbin/e2fsck
+manual_add_modules squashfs

=== modified file 'scripts/ubuntu-core-rootfs'
--- scripts/ubuntu-core-rootfs	2015-08-24 13:54:01 +0000
+++ scripts/ubuntu-core-rootfs	2015-10-21 13:53:20 +0000
@@ -147,60 +147,10 @@
 	done
 }
 
-#---------------------------------------------------------------------
-# XXX: Entry point - called by the initramfs "/init" script.
-#---------------------------------------------------------------------
-mountroot()
+fsck_writable()
 {
-	local writable_label="writable"
-
-	local writable_mnt="/tmpmnt_${writable_label}"
-
-	pre_mountroot
-
-	[ "$quiet" != "y" ] && log_begin_msg "Running /scripts/local-premount"
-	run_scripts /scripts/local-premount
-	[ "$quiet" != "y" ] && log_end_msg
-
-	# There are 2 root partitions but grub tells us which to boot
-	# with via "root="
-	for x in $(cat /proc/cmdline); do
-		case "${x}" in
-		root=*)
-			root="${x#*=}"
-			;;
-		esac
-	done
-
-	# Make sure the device has been created by udev before we try to mount
-	wait-for-root "$root" "${ROOTDELAY:-180}" || panic "unable to find root partition '$root'"
-
-	[ -n "$root" ] || panic "no root partition specified"
-
-	if echo "$root" | grep -q ^/; then
-		path="$root"
-	else
-		# convert UUID/LABEL to a device name
-		path=$(findfs "$root" 2>/dev/null || :)
-	fi
-
-	[ -e "$path" ] || panic "root device $path does not exist"
-
-	# Mount the root filesystem read-only.
-	echo "initrd: mounting $path" >/dev/kmsg || true
-	mount -o defaults,ro "$path" "$rootmnt"
-
-	rootpath="$path"
-
-	# Create a read-only bind mount on top of the already read-only
-	# FS. This is to stop the system from noticing when the root
-	# filesystem is made writable (when system updates are applied).
-	mount -o bind,ro "$rootmnt" "$rootmnt"
-
-	echo "initrd: mounting /run" >/dev/kmsg || true
-	mount -o rw,nosuid,noexec,relatime,mode=755 -t tmpfs tmpfs "${rootmnt}/run"
-
-	mkdir -p "$writable_mnt"
+	local writable_label="$1"
+        local writable_mnt="$2"
 
 	path=$(get_partition_from_label "$writable_label")
 
@@ -226,9 +176,122 @@
 
 	echo "$(date '+%s'): end" >> "$logfile" || true
 
-	echo "initrd: mounting $writable_label partition" >/dev/kmsg || true
-	mount "$path" "$writable_mnt"
-	mkdir -p "${rootmnt}/writable"
+}
+
+# setup $rootmnt based on os/kernel snaps
+do_new_style_root_mounting()
+{
+        root="LABEL=$writable_label"
+
+	# Make sure the device has been created by udev before we try to mount
+	wait-for-root "$root" "${ROOTDELAY:-180}" || panic "unable to find root partition '$root'"
+
+	[ -n "$root" ] || panic "no root partition specified"
+
+	if echo "$root" | grep -q ^/; then
+		path="$root"
+	else
+		# convert UUID/LABEL to a device name
+		path=$(findfs "$root" 2>/dev/null || :)
+	fi
+
+	[ -e "$path" ] || panic "root device $path does not exist"
+
+        # FIXME: meh, system should figure this out
+        #insmod ./lib/modules/*/kernel/fs/nls/nls_iso8859-1.ko
+        insmod ./lib/modules/*/kernel/fs/squashfs/squashfs.ko
+
+        # mount writable rw
+        path=$(get_partition_from_label "$writable_label")
+        mount "$path" "$writable_mnt"
+
+        # mount OS snap
+        mount "${writable_mnt}/system-data/var/lib/snappy/snaps/${snappy_os}" "$rootmnt"
+
+        # now add a kernel bind mounts to it
+        local kernel_mnt="/tmpmnt_kernel"
+        mkdir -p "$kernel_mnt"
+        mount "${writable_mnt}/system-data/var/lib/snappy/snaps/${snappy_kernel}" "$kernel_mnt"
+        for d in modules firmware; do
+            mount -o bind "${kernel_mnt}/lib/$d" "$rootmnt/lib/$d"            
+        done
+}    
+
+# setup $rootmnt from system_ab style
+do_old_style_root_mounting()
+{
+	# Make sure the device has been created by udev before we try to mount
+	wait-for-root "$root" "${ROOTDELAY:-180}" || panic "unable to find root partition '$root'"
+
+	[ -n "$root" ] || panic "no root partition specified"
+
+	if echo "$root" | grep -q ^/; then
+		path="$root"
+	else
+		# convert UUID/LABEL to a device name
+		path=$(findfs "$root" 2>/dev/null || :)
+	fi
+
+	[ -e "$path" ] || panic "root device $path does not exist"
+
+	# Mount the root filesystem read-only.
+	echo "initrd: mounting $path" >/dev/kmsg || true
+	mount -o defaults,ro "$path" "$rootmnt"
+
+	rootpath="$path"
+
+	# Create a read-only bind mount on top of the already read-only
+	# FS. This is to stop the system from noticing when the root
+	# filesystem is made writable (when system updates are applied).
+	mount -o bind,ro "$rootmnt" "$rootmnt"
+}
+    
+#---------------------------------------------------------------------
+# XXX: Entry point - called by the initramfs "/init" script.
+#---------------------------------------------------------------------
+mountroot()
+{
+        pre_mountroot
+
+	[ "$quiet" != "y" ] && log_begin_msg "Running /scripts/local-premount"
+	run_scripts /scripts/local-premount
+	[ "$quiet" != "y" ] && log_end_msg
+        
+        # find what snappy-os version to use
+        for x in $(cat /proc/cmdline); do
+	    case "${x}" in
+                # new kernel/os snap vars
+		snappy_os=*)
+			snappy_os="${x#*=}"
+			;;
+		snappy_kernel=*)
+			snappy_kernel="${x#*=}"
+			;;
+                # old system-ab style
+		root=*)
+			root="${x#*=}"
+			;;
+		esac
+	done
+
+        # always ensure writable is in a good state
+        writable_label="writable"
+        writable_mnt="/tmpmnt_${writable_label}"
+	mkdir -p "$writable_mnt"
+        fsck_writable "$writable_label" "$writable_mnt"
+
+        # check if we are on a new os/kernel snap system or a old snappy_ab one
+        if [ -n "$snappy_os" ] && [ -n "$snappy_kernel" ]; then
+            do_new_style_root_mounting
+        else
+            do_old_style_root_mounting
+        fi
+        
+        # mount /run
+	echo "initrd: mounting /run" >/dev/kmsg || true
+	mount -o rw,nosuid,noexec,relatime,mode=755 -t tmpfs tmpfs "${rootmnt}/run"
+
+        # move /writable to its final destination
 	mount --move "$writable_mnt" "${rootmnt}/writable"
 
 	# Prepare the fstab
@@ -243,7 +306,11 @@
 		echo "# DO NOT EDIT THIS FILE BY HAND - YOUR CHANGES WILL BE OVERWRITTEN" >> "$fstab"
 		echo "# (See writable-paths(5) for details)" >> "$fstab"
 		echo "/dev/root / rootfs defaults,ro 0 0" >> "$fstab"
-
+                # FIXME: ideally we would mount /writable RO here and
+                #        let systemd do a "remount,rw" for us. unfortunately
+                #        this is not supported by systemd so we need to do
+                #        the RW mount and fsck dance etc here :/
+                echo "LABEL=writable /writable auto defaults 0 0" >> "$fstab"
 		handle_writable_paths "$writable_paths" "$fstab"
 	fi
 
@@ -273,6 +340,7 @@
 		fi
 	fi
 
+        # FIXME: the below can go away once we no longer support snappy_ab
 	# add an fstab entry to mount the "other" rootfs partition read-only
 	partition=$(findfs LABEL="system-b" 2>/dev/null || :)
 	abs_rootpath=$(readlink -f "$rootpath" || :)
@@ -281,11 +349,10 @@
 	else
 		other="$partition"
 	fi
-
 	if [ -n "$other" ]; then
 		echo "$other /writable/cache/system auto defaults,ro 0 0" >> "$fstab"
-	fi
-
+        fi
+        
 	# Mount the systemd overlay so that we have a complete root partition during boot
 	mkdir -p "${rootmnt}/writable/system-data/etc/systemd/system"
 	mount -o bind "${rootmnt}/writable/system-data/etc/systemd/system" "${rootmnt}/etc/systemd/system"