Evaluate the @root volume name also for btrfs

build-tests/x86/fedora/test-image-live-disk/appliance.kiwi

@@ -30,7 +30,11 @@
         </type>
     </preferences>
     <preferences profiles="Virtual">
-        <type image="oem" filesystem="ext4" kernelcmdline="console=ttyS0" firmware="uefi" format="qcow2">
+        <type image="oem" filesystem="btrfs" kernelcmdline="console=ttyS0 rootflags=subvol=root" firmware="uefi" format="qcow2" btrfs_root_is_subvolume="true" btrfs_set_default_volume="false" rootfs_label="fedora" bootpartition="true" bootfilesystem="ext4">
+            <systemdisk name="fedora">
+                <volume name="@root=root"/>
+                <volume name="home" parent="/"/>
+            </systemdisk>
             <oemconfig>
                 <oem-resize>false</oem-resize>
             </oemconfig>
@@ -67,6 +71,7 @@
         <package name="vim"/>
         <package name="tzdata"/>
         <package name="NetworkManager"/>
+        <package name="btrfs-progs"/>
     </packages>
     <packages type="image" profiles="Live,Disk">
         <package name="syslinux"/>

doc/source/image_description/elements.rst

@@ -412,6 +412,28 @@ btrfs_quota_groups="true|false":
   Boolean parameter to activate filesystem quotas if
   the filesystem is `btrfs`. By default quotas are inactive.
 
+btrfs_set_default_volume="true|false":
+  Tell kiwi to explicitly make a volume the default volume
+  This can be either `/` or the root subvolume or the root
+  snapshot depending on the specified btrfs configuration
+  attributes. By default btrfs_set_default_volume is set to: true
+  If no default volume should be set, this attribute can be
+  used to turn it off
+
+btrfs_root_is_subvolume="true|false":
+  Tell kiwi to create a root volume to host (/) inside.
+  The name of this subvolume is by default set to: `@`.
+  The name of the subvolume can be changed via a volume entry
+  of the form:
+
+  .. code:: xml
+
+     <systemdisk>
+       <volume name="@root=TOPLEVEL_NAME"/>
+     </systemdisk>
+
+  By default the creation of a toplevel volume is set to: `true`
+
 btrfs_root_is_snapshot="true|false":
   Boolean parameter that tells {kiwi} to install
   the system into a btrfs snapshot. The snapshot layout is compatible with

kiwi/bootloader/config/base.py

@@ -501,7 +501,8 @@ def get_gfxmode(self, target):
             return gfxmode
 
     def _mount_system(
-        self, root_device, boot_device, efi_device=None, volumes=None
+        self, root_device, boot_device, efi_device=None,
+        volumes=None, root_volume_name=None
     ):
         self.root_mount = MountManager(
             device=root_device
@@ -522,7 +523,10 @@ def _mount_system(
                 mountpoint=self.root_mount.mountpoint + '/boot/efi'
             )
 
-        self.root_mount.mount()
+        custom_root_mount_args = []
+        if root_volume_name and root_volume_name != '/':
+            custom_root_mount_args += [f'subvol={root_volume_name}']
+        self.root_mount.mount(options=custom_root_mount_args)
 
         if not self.root_mount.device == self.boot_mount.device:
             self.boot_mount.mount()

kiwi/bootloader/config/grub2.py

@@ -233,14 +233,18 @@ def setup_disk_image_config(
                 'root_device': string,
                 'boot_device': string,
                 'efi_device': string,
-                'system_volumes': volume_manager_instance.get_volumes()
+                'system_volumes':
+                    volume_manager_instance.get_volumes(),
+                'system_root_volume':
+                    volume_manager_instance.get_root_volume_name()
             }
         """
         self._mount_system(
             boot_options.get('root_device'),
             boot_options.get('boot_device'),
             boot_options.get('efi_device'),
-            boot_options.get('system_volumes')
+            boot_options.get('system_volumes'),
+            boot_options.get('system_root_volume')
         )
         config_file = os.sep.join(
             [
@@ -809,35 +813,47 @@ def _setup_secure_boot_efi_image(
             # a grub image that got signed by the shim. The shim image
             # is the one that gets loaded by the firmware which itself
             # loads the second stage grub image
-            log.info(
-                f'--> Using shim image: {shim_image.filename}'
-            )
-            log.info(
-                f'--> Using grub image: {grub_image.filename}'
-            )
-            Command.run(
-                ['cp', shim_image.filename, self._get_efi_image_name()]
-            )
-            Command.run(
-                [
-                    'cp', grub_image.filename,
-                    os.sep.join([self.efi_boot_path, grub_image.binaryname])
-                ]
+            target_efi_image_name = self._get_efi_image_name()
+            target_grub_image_name = os.sep.join(
+                [self.efi_boot_path, grub_image.binaryname]
             )
+            if not os.path.isfile(target_efi_image_name):
+                log.info(
+                    f'--> Using shim image: {shim_image.filename}'
+                )
+                Command.run(
+                    ['cp', shim_image.filename, target_efi_image_name]
+                )
+            if not os.path.isfile(target_grub_image_name):
+                log.info(
+                    f'--> Using grub image: {grub_image.filename}'
+                )
+                Command.run(
+                    ['cp', grub_image.filename, target_grub_image_name]
+                )
             mok_manager = Defaults.get_mok_manager(lookup_path)
             if mok_manager:
-                Command.run(
-                    ['cp', mok_manager, self.efi_boot_path]
+                target_mok_manager = os.sep.join(
+                    [self.efi_boot_path, os.path.basename(mok_manager)]
                 )
+                if not os.path.isfile(target_mok_manager):
+                    log.info(
+                        f'--> Using mok image: {mok_manager}'
+                    )
+                    Command.run(
+                        ['cp', mok_manager, self.efi_boot_path]
+                    )
         else:
             # Without shim a self signed grub image is used that
             # gets loaded by the firmware
-            log.info(
-                f'--> No shim image, using grub image: {grub_image.filename}'
-            )
-            Command.run(
-                ['cp', grub_image.filename, self._get_efi_image_name()]
-            )
+            target_efi_image_name = self._get_efi_image_name()
+            if not os.path.isfile(target_efi_image_name):
+                log.info(
+                    f'--> No shim image, using grub image: {grub_image.filename}'
+                )
+                Command.run(
+                    ['cp', grub_image.filename, target_efi_image_name]
+                )
         self._create_efi_config_search(uuid, mbrid)
 
     def _setup_efi_image(

kiwi/bootloader/install/grub2.py

@@ -52,6 +52,7 @@ def post_init(self, custom_args):
                 {
                     'target_removable': bool,
                     'system_volumes': list_of_volumes,
+                    'system_root_volume': root volume name if required
                     'firmware': FirmWare_instance,
                     'efi_device': string,
                     'boot_device': string,
@@ -71,12 +72,15 @@ def post_init(self, custom_args):
         self.proc_mount = None
         self.sysfs_mount = None
         self.volumes = None
+        self.root_volume_name = None
         self.volumes_mount = []
         self.target_removable = None
         if custom_args and 'target_removable' in custom_args:
             self.target_removable = custom_args['target_removable']
         if custom_args and 'system_volumes' in custom_args:
             self.volumes = custom_args['system_volumes']
+        if custom_args and 'system_root_volume' in custom_args:
+            self.root_volume_name = custom_args['system_root_volume']
         if custom_args and 'firmware' in custom_args:
             self.firmware = custom_args['firmware']
         if custom_args and 'install_options' in custom_args:
@@ -302,7 +306,10 @@ def _mount_device_and_volumes(self):
             self.root_mount = MountManager(
                 device=self.custom_args['root_device']
             )
-            self.root_mount.mount()
+            custom_root_mount_args = []
+            if self.root_volume_name and self.root_volume_name != '/':
+                custom_root_mount_args += [f'subvol={self.root_volume_name}']
+            self.root_mount.mount(options=custom_root_mount_args)
 
         if self.boot_mount is None:
             if 's390' in self.arch:

kiwi/builder/disk.py

@@ -417,6 +417,12 @@ def create_disk(self) -> Result:
                 'root_is_readonly_snapshot':
                     self.xml_state.build_type.
                     get_btrfs_root_is_readonly_snapshot(),
+                'root_is_subvolume':
+                    self.xml_state.build_type.
+                    get_btrfs_root_is_subvolume(),
+                'set_default_volume':
+                    self.xml_state.build_type.
+                    get_btrfs_set_default_volume(),
                 'quota_groups':
                     self.xml_state.build_type.get_btrfs_quota_groups(),
                 'resize_on_boot':
@@ -1116,6 +1122,13 @@ def _write_generic_fstab(
             custom_root_mount_args += ['ro']
             fs_check_interval = '0 0'
 
+        if self.volume_manager_name and self.volume_manager_name == 'btrfs':
+            root_volume_name = system.get_root_volume_name()
+            if root_volume_name != '/':
+                custom_root_mount_args += [
+                    f'defaults,subvol={root_volume_name}'
+                ]
+
         self._add_fstab_entry(
             device_map['root'].get_device(), '/',
             custom_root_mount_args, fs_check_interval
@@ -1524,7 +1537,12 @@ def _install_bootloader(
         if self.volume_manager_name:
             system.umount_volumes()
             custom_install_arguments.update(
-                {'system_volumes': system.get_volumes()}
+                {
+                    'system_volumes': system.get_volumes(),
+                    'system_root_volume':
+                        system.get_root_volume_name()
+                        if self.volume_manager_name == 'btrfs' else None
+                }
             )
 
         if self.bootloader != 'custom':

kiwi/mount_manager.py

@@ -19,7 +19,9 @@
 import time
 import logging
 from textwrap import dedent
-from typing import List
+from typing import (
+    List, Dict
+)
 
 # project
 from kiwi.path import Path
@@ -41,9 +43,14 @@ class MountManager:
 
     * :param string device: device node name
     * :param string mountpoint: mountpoint directory name
+    * :param dict attributes: optional attributes to store
     """
-    def __init__(self, device: str, mountpoint: str = ''):
+    def __init__(
+        self, device: str, mountpoint: str = '',
+        attributes: Dict[str, str] = {}
+    ):
         self.device = device
+        self.attributes = attributes
         if not mountpoint:
             self.mountpoint_tempdir = Temporary(
                 prefix='kiwi_mount_manager.'
@@ -53,6 +60,12 @@ def __init__(self, device: str, mountpoint: str = ''):
             Path.create(mountpoint)
             self.mountpoint = mountpoint
 
+    def get_attributes(self) -> Dict[str, str]:
+        """
+        Return attributes dict for this mount manager
+        """
+        return self.attributes
+
     def bind_mount(self) -> None:
         """
         Bind mount the device to the mountpoint

kiwi/schema/kiwi.rnc

@@ -1433,6 +1433,29 @@ div {
             sch:param [ name = "attr" value = "btrfs_quota_groups" ]
             sch:param [ name = "types" value = "oem" ]
         ]
+    k.type.btrfs_set_default_volume.attribute =
+        ## Tell kiwi to explicitly make a volume the default volume
+        ## This can be either (/) or the root subvolume or the root
+        ## snapshot depending on the specified btrfs configuration
+        ## attributes. By default btrfs_set_default_volume is set to: true
+        ## If no default volume should be set, this attribute can be
+        ## used to turn it off
+        attribute btrfs_set_default_volume { xsd:boolean }
+        >> sch:pattern [ id = "btrfs_set_default_volume" is-a = "image_type"
+            sch:param [ name = "attr" value = "btrfs_set_default_volume" ]
+            sch:param [ name = "types" value = "oem" ]
+        ]
+    k.type.btrfs_root_is_subvolume.attribute =
+        ## Tell kiwi to create a root volume to host (/) inside.
+        ## The name of this subvolume is by default set to: '@'
+        ## The name of the subvolume can be changed via
+        ## a volume entry of the form '<volume name="@root=NAME"/>'
+        ## By default the creation of a root subvolume is set to: true
+        attribute btrfs_root_is_subvolume { xsd:boolean }
+        >> sch:pattern [ id = "btrfs_root_is_subvolume" is-a = "image_type"
+            sch:param [ name = "attr" value = "btrfs_root_is_subvolume" ]
+            sch:param [ name = "types" value = "oem" ]
+        ]
     k.type.btrfs_root_is_snapshot.attribute =
         ## Tell kiwi to install the system into a btrfs snapshot
         ## The snapshot layout is compatible with the snapper management
@@ -2218,6 +2241,8 @@ div {
         k.type.bootprofile.attribute? &
         k.type.btrfs_quota_groups.attribute? &
         k.type.btrfs_root_is_snapshot.attribute? &
+        k.type.btrfs_root_is_subvolume.attribute? &
+        k.type.btrfs_set_default_volume.attribute? &
         k.type.btrfs_root_is_readonly_snapshot.attribute? &
         k.type.compressed.attribute? &
         k.type.devicepersistency.attribute? &
@@ -2552,6 +2577,13 @@ div {
         ## not specified the name specifies a path which has to
         ## exist inside the root directory.
         attribute name { text }
+    k.volume.parent.attribute =
+        ## The name/path of the parent volume.
+        ## Evaluated only for the btrfs volume manager to allow
+        ## specifying the parent subvolume to nest this volume in.
+        ## If not specified the parent is always the volume set
+        ## as the default volume
+        attribute parent { text }
     k.volume.mountpoint.attribute =
         ## volume path. The mountpoint specifies a path which has to
         ## exist inside the root directory.
@@ -2584,6 +2616,7 @@ div {
         k.volume.mountpoint.attribute? &
         k.volume.label.attribute? &
         k.volume.name.attribute &
+        k.volume.parent.attribute? &
         k.volume.size.attribute?
     k.volume =
         ## Specify which parts of the filesystem should be