WIP experimental btrfs setup

Signed-off-by: David Cassany <dcassany@suse.com>
davidcassany · Oct 20, 2023 · db4a18b · db4a18b
1 parent fd92278
commit db4a18b
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Showing 6 changed files with 32 additions and 29 deletions.
diff --git a/examples/green/Dockerfile b/examples/green/Dockerfile
@@ -42,6 +42,9 @@ RUN ARCH=$(uname -m); \
       less \
       sudo \
       curl \
+      btrfsprogs \
+      snapper \
+      tukit \
       sed
 
 # Just add the elemental cli

diff --git a/pkg/features/embedded/grub-config/etc/cos/grub.cfg b/pkg/features/embedded/grub-config/etc/cos/grub.cfg
@@ -42,40 +42,30 @@ insmod all_video
 insmod gfxterm
 insmod loopback
 insmod squash4
+insmod btrfs
 
 set loopdev="loop0"
+set btrfs_relative_path="y"
 
 menuentry "${display_name}" --id cos {
-  # label is kept around for backward compatibility
-  set label=${active_label}
-  set img=/cOS/active.img
-  loopback $loopdev /$img
-  source ($loopdev)/etc/cos/bootargs.cfg
-  linux ($loopdev)$kernel $kernelcmd ${extra_cmdline} ${extra_active_cmdline}
-  initrd ($loopdev)$initramfs
-  loopback -d $loopdev
+  btrfs-mount-subvol ($root) / ${active_snapshot}
+  set img=${active_snapshot}
+  source /etc/cos/bootargs.cfg
+  linux $kernel $kernelcmd ${extra_cmdline} ${extra_active_cmdline}
+  initrd $initramfs
 }
 
 menuentry "${display_name} (fallback)" --id fallback {
-  # label is kept around for backward compatibility
-  set label=${passive_label}
-  set img=/cOS/passive.img
-  loopback $loopdev /$img
-  source ($loopdev)/etc/cos/bootargs.cfg
-  linux ($loopdev)$kernel $kernelcmd ${extra_cmdline} ${extra_passive_cmdline}
-  initrd ($loopdev)$initramfs
-  loopback -d $loopdev
+  btrfs-mount-subvol ($root) / ${passive_snapshot}
+  set img=${passive_snapshot}
+  source /etc/cos/bootargs.cfg
+  linux $kernel $kernelcmd ${extra_cmdline} ${extra_passive_cmdline}
+  initrd $initramfs
 }
 
 menuentry "${display_name} recovery" --id recovery {
-  # label and recoverylabel are kept around for backward compatibility
-  if [ -n "${system_label}" ]; then
-    set label=${system_label}
-  else
-    set recoverylabel=${recovery_label}
-  fi
-  set img=/cOS/recovery.img
   search --no-floppy --label --set=root $recovery_label
+  set img=/cOS/recovery.img
   loopback $loopdev /$img
   source ($loopdev)/etc/cos/bootargs.cfg
   linux ($loopdev)$kernel $kernelcmd ${extra_cmdline} ${extra_recovery_cmdline}

diff --git a/pkg/features/embedded/grub-default-bootargs/etc/cos/bootargs.cfg b/pkg/features/embedded/grub-default-bootargs/etc/cos/bootargs.cfg
@@ -3,6 +3,6 @@ set kernel=/boot/vmlinuz
 if [ "${img}" == "/cOS/recovery.img" ]; then
   set kernelcmd="console=tty1 console=ttyS0 root=LABEL=$recovery_label cos-img/filename=$img security=selinux selinux=0 rd.neednet=1 rd.cos.oemlabel=$oem_label rd.cos.mount=LABEL=$oem_label:/oem"
 else
-  set kernelcmd="console=tty1 console=ttyS0 root=LABEL=$state_label cos-img/filename=$img panic=5 security=selinux selinux=1 rd.neednet=1 rd.cos.oemlabel=$oem_label rd.cos.mount=LABEL=$oem_label:/oem rd.cos.mount=LABEL=$persistent_label:/usr/local fsck.mode=force fsck.repair=yes"
+  set kernelcmd="console=tty1 console=ttyS0 root=LABEL=$state_label cos-img/filename=$img panic=5 security=selinux selinux=1 rd.neednet=1 rd.cos.oemlabel=$oem_label rd.cos.mount=LABEL=$oem_label:/oem rd.cos.mount=LABEL=$persistent_label:/usr/local"
 fi
 set initramfs=/boot/initrd
diff --git a/...table-rootfs/usr/lib/dracut/modules.d/30elemental-immutable-rootfs/elemental-generator.sh b/...table-rootfs/usr/lib/dracut/modules.d/30elemental-immutable-rootfs/elemental-generator.sh
@@ -148,8 +148,8 @@ mkdir -p "$GENERATOR_DIR/$dev.device.d"
     echo "RequiresMountsFor=${root_part_mnt}"
     echo "[Mount]"
     echo "Where=/sysroot"
-    echo "What=${root_part_mnt}/${cos_img#/}"
-    echo "Options=${cos_root_perm},suid,dev,exec,auto,nouser,async"
+    echo "What=${root}"
+    echo "Options=${cos_root_perm},subvol=${cos_img},suid,dev,exec,auto,nouser,async"
 } > "$GENERATOR_DIR"/sysroot.mount
 
 if [ ! -e "$GENERATOR_DIR/initrd-root-fs.target.requires/sysroot.mount" ]; then

diff --git a/...le-rootfs/usr/lib/dracut/modules.d/30elemental-immutable-rootfs/elemental-mount-layout.sh b/...le-rootfs/usr/lib/dracut/modules.d/30elemental-immutable-rootfs/elemental-mount-layout.sh
@@ -260,12 +260,18 @@ readLayoutConfig
 
 [ -z "${cos_overlay}" ] && exit 0
 
+# Hack to get the root device and its mounted subvolume
+snapshot=${root##*[}
+snapshot=${snapshot%%]}
+root=${root%%[*}
+
 # If sysroot is already an overlay do not prepare the rw overlay
 if [ "${root_fstype}" != "overlay" ]; then
     if [ -f "${base_part}" ]; then
         fstab="${base_part} /run/initramfs/cos-state auto ${cos_root_perm} 0 0\n"
     fi
-    fstab+="${root} / auto ${cos_root_perm} 0 0\n"
+
+    fstab+="${root} / auto ${cos_root_perm},subvol=${snapshot} 0 0\n"
     fstab+=$(mountOverlayBase)
 fi
 

diff --git a/pkg/utils/grub.go b/pkg/utils/grub.go
@@ -39,9 +39,13 @@ const (
 	grubCfgFile     = "grub.cfg"
 
 	grubEFICfgTmpl = `
+insmod btrfs
+
+set btrfs_relative_path="y"
+
 search --no-floppy --label --set=root %s
 set prefix=($root)/` + grubConfDir + `
-configfile ($root)/` + grubConfDir + `/%s
+configfile ${prefix}/` + grubCfgFile + `
 `
 )
 
@@ -254,7 +258,7 @@ func (g Grub) InstallEFI(rootDir, bootDir, efiDir, deviceLabel string) (string,
 	// Add grub.cfg in EFI that chainloads the grub.cfg in recovery
 	// Notice that we set the config to /grub2/grub.cfg which means the above we need to copy the file from
 	// the installation source into that dir
-	grubCfgContent := []byte(fmt.Sprintf(grubEFICfgTmpl, deviceLabel, grubCfgFile))
+	grubCfgContent := []byte(fmt.Sprintf(grubEFICfgTmpl, deviceLabel))
 	// Fallback
 	err = g.config.Fs.WriteFile(filepath.Join(efiDir, fallbackEFIPath, grubCfgFile), grubCfgContent, cnst.FilePerm)
 	if err != nil {