diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 90e7fe51fa74a..36c346eeee766 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -1220,6 +1220,7 @@
     'OC\\Files\\ObjectStore\\Mapper' => $baseDir . '/lib/private/Files/ObjectStore/Mapper.php',
     'OC\\Files\\ObjectStore\\NoopScanner' => $baseDir . '/lib/private/Files/ObjectStore/NoopScanner.php',
     'OC\\Files\\ObjectStore\\ObjectStoreStorage' => $baseDir . '/lib/private/Files/ObjectStore/ObjectStoreStorage.php',
+    'OC\\Files\\ObjectStore\\PrimaryObjectStoreConfig' => $baseDir . '/lib/private/Files/ObjectStore/PrimaryObjectStoreConfig.php',
     'OC\\Files\\ObjectStore\\S3' => $baseDir . '/lib/private/Files/ObjectStore/S3.php',
     'OC\\Files\\ObjectStore\\S3ConnectionTrait' => $baseDir . '/lib/private/Files/ObjectStore/S3ConnectionTrait.php',
     'OC\\Files\\ObjectStore\\S3ObjectTrait' => $baseDir . '/lib/private/Files/ObjectStore/S3ObjectTrait.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index 8cef29efc39bc..ffc09ad71aba5 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -1253,6 +1253,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OC\\Files\\ObjectStore\\Mapper' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/Mapper.php',
         'OC\\Files\\ObjectStore\\NoopScanner' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/NoopScanner.php',
         'OC\\Files\\ObjectStore\\ObjectStoreStorage' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/ObjectStoreStorage.php',
+        'OC\\Files\\ObjectStore\\PrimaryObjectStoreConfig' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/PrimaryObjectStoreConfig.php',
         'OC\\Files\\ObjectStore\\S3' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/S3.php',
         'OC\\Files\\ObjectStore\\S3ConnectionTrait' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/S3ConnectionTrait.php',
         'OC\\Files\\ObjectStore\\S3ObjectTrait' => __DIR__ . '/../../..' . '/lib/private/Files/ObjectStore/S3ObjectTrait.php',
diff --git a/lib/private/Files/Mount/ObjectHomeMountProvider.php b/lib/private/Files/Mount/ObjectHomeMountProvider.php
index 77912adfd34ed..0afe573232e98 100644
--- a/lib/private/Files/Mount/ObjectHomeMountProvider.php
+++ b/lib/private/Files/Mount/ObjectHomeMountProvider.php
@@ -24,117 +24,40 @@
  */
 namespace OC\Files\Mount;
 
+use OC\Files\ObjectStore\HomeObjectStoreStorage;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
 use OCP\Files\Config\IHomeMountProvider;
+use OCP\Files\Mount\IMountPoint;
 use OCP\Files\Storage\IStorageFactory;
-use OCP\IConfig;
 use OCP\IUser;
-use Psr\Log\LoggerInterface;
 
 /**
  * Mount provider for object store home storages
  */
 class ObjectHomeMountProvider implements IHomeMountProvider {
-	/**
-	 * @var IConfig
-	 */
-	private $config;
+	private PrimaryObjectStoreConfig $objectStoreConfig;
 
-	/**
-	 * ObjectStoreHomeMountProvider constructor.
-	 *
-	 * @param IConfig $config
-	 */
-	public function __construct(IConfig $config) {
-		$this->config = $config;
+	public function __construct(PrimaryObjectStoreConfig $objectStoreConfig) {
+		$this->objectStoreConfig = $objectStoreConfig;
 	}
 
 	/**
-	 * Get the cache mount for a user
+	 * Get the home mount for a user
 	 *
 	 * @param IUser $user
 	 * @param IStorageFactory $loader
-	 * @return \OCP\Files\Mount\IMountPoint
-	 */
-	public function getHomeMountForUser(IUser $user, IStorageFactory $loader) {
-		$config = $this->getMultiBucketObjectStoreConfig($user);
-		if ($config === null) {
-			$config = $this->getSingleBucketObjectStoreConfig($user);
-		}
-
-		if ($config === null) {
-			return null;
-		}
-
-		return new MountPoint('\OC\Files\ObjectStore\HomeObjectStoreStorage', '/' . $user->getUID(), $config['arguments'], $loader, null, null, self::class);
-	}
-
-	/**
-	 * @param IUser $user
-	 * @return array|null
-	 */
-	private function getSingleBucketObjectStoreConfig(IUser $user) {
-		$config = $this->config->getSystemValue('objectstore');
-		if (!is_array($config)) {
-			return null;
-		}
-
-		// sanity checks
-		if (empty($config['class'])) {
-			\OC::$server->get(LoggerInterface::class)->error('No class given for objectstore', ['app' => 'files']);
-		}
-		if (!isset($config['arguments'])) {
-			$config['arguments'] = [];
-		}
-		// instantiate object store implementation
-		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
-
-		$config['arguments']['user'] = $user;
-
-		return $config;
-	}
-
-	/**
-	 * @param IUser $user
-	 * @return array|null
+	 * @return ?IMountPoint
 	 */
-	private function getMultiBucketObjectStoreConfig(IUser $user) {
-		$config = $this->config->getSystemValue('objectstore_multibucket');
-		if (!is_array($config)) {
+	public function getHomeMountForUser(IUser $user, IStorageFactory $loader): ?IMountPoint {
+		$objectStore = $this->objectStoreConfig->getObjectStoreForUser($user);
+		if ($objectStore === null) {
 			return null;
 		}
+		$arguments = array_merge($this->objectStoreConfig->getObjectStoreArgumentsForUser($user), [
+			'objectstore' => $objectStore,
+			'user' => $user,
+		]);
 
-		// sanity checks
-		if (empty($config['class'])) {
-			\OC::$server->get(LoggerInterface::class)->error('No class given for objectstore', ['app' => 'files']);
-		}
-		if (!isset($config['arguments'])) {
-			$config['arguments'] = [];
-		}
-
-		$bucket = $this->config->getUserValue($user->getUID(), 'homeobjectstore', 'bucket', null);
-
-		if ($bucket === null) {
-			/*
-			 * Use any provided bucket argument as prefix
-			 * and add the mapping from username => bucket
-			 */
-			if (!isset($config['arguments']['bucket'])) {
-				$config['arguments']['bucket'] = '';
-			}
-			$mapper = new \OC\Files\ObjectStore\Mapper($user, $this->config);
-			$numBuckets = isset($config['arguments']['num_buckets']) ? $config['arguments']['num_buckets'] : 64;
-			$config['arguments']['bucket'] .= $mapper->getBucket($numBuckets);
-
-			$this->config->setUserValue($user->getUID(), 'homeobjectstore', 'bucket', $config['arguments']['bucket']);
-		} else {
-			$config['arguments']['bucket'] = $bucket;
-		}
-
-		// instantiate object store implementation
-		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
-
-		$config['arguments']['user'] = $user;
-
-		return $config;
+		return new MountPoint(HomeObjectStoreStorage::class, '/' . $user->getUID(), $arguments, $loader, null, null, self::class);
 	}
 }
diff --git a/lib/private/Files/Mount/RootMountProvider.php b/lib/private/Files/Mount/RootMountProvider.php
index b301fc6dd149d..c3e302541a4a2 100644
--- a/lib/private/Files/Mount/RootMountProvider.php
+++ b/lib/private/Files/Mount/RootMountProvider.php
@@ -25,79 +25,42 @@
 
 use OC;
 use OC\Files\ObjectStore\ObjectStoreStorage;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
 use OC\Files\Storage\LocalRootStorage;
-use OC_App;
 use OCP\Files\Config\IRootMountProvider;
+use OCP\Files\ObjectStore\IObjectStore;
 use OCP\Files\Storage\IStorageFactory;
 use OCP\IConfig;
-use Psr\Log\LoggerInterface;
 
 class RootMountProvider implements IRootMountProvider {
+	private PrimaryObjectStoreConfig $objectStoreConfig;
 	private IConfig $config;
-	private LoggerInterface $logger;
 
-	public function __construct(IConfig $config, LoggerInterface $logger) {
+	public function __construct(PrimaryObjectStoreConfig $objectStoreConfig, IConfig $config) {
+		$this->objectStoreConfig = $objectStoreConfig;
 		$this->config = $config;
-		$this->logger = $logger;
 	}
 
 	public function getRootMounts(IStorageFactory $loader): array {
-		$objectStore = $this->config->getSystemValue('objectstore', null);
-		$objectStoreMultiBucket = $this->config->getSystemValue('objectstore_multibucket', null);
+		$objectStore = $this->objectStoreConfig->getObjectStoreForRoot();
 
-		if ($objectStoreMultiBucket) {
-			return [$this->getMultiBucketStoreRootMount($loader, $objectStoreMultiBucket)];
-		} elseif ($objectStore) {
+		if ($objectStore) {
 			return [$this->getObjectStoreRootMount($loader, $objectStore)];
 		} else {
 			return [$this->getLocalRootMount($loader)];
 		}
 	}
 
-	private function validateObjectStoreConfig(array &$config) {
-		if (empty($config['class'])) {
-			$this->logger->error('No class given for objectstore', ['app' => 'files']);
-		}
-		if (!isset($config['arguments'])) {
-			$config['arguments'] = [];
-		}
-
-		// instantiate object store implementation
-		$name = $config['class'];
-		if (strpos($name, 'OCA\\') === 0 && substr_count($name, '\\') >= 2) {
-			$segments = explode('\\', $name);
-			OC_App::loadApp(strtolower($segments[1]));
-		}
-	}
-
 	private function getLocalRootMount(IStorageFactory $loader): MountPoint {
 		$configDataDirectory = $this->config->getSystemValue("datadirectory", OC::$SERVERROOT . "/data");
 		return new MountPoint(LocalRootStorage::class, '/', ['datadir' => $configDataDirectory], $loader, null, null, self::class);
 	}
 
-	private function getObjectStoreRootMount(IStorageFactory $loader, array $config): MountPoint {
-		$this->validateObjectStoreConfig($config);
-
-		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
-		// mount with plain / root object store implementation
-		$config['class'] = ObjectStoreStorage::class;
-
-		return new MountPoint($config['class'], '/', $config['arguments'], $loader, null, null, self::class);
-	}
-
-	private function getMultiBucketStoreRootMount(IStorageFactory $loader, array $config): MountPoint {
-		$this->validateObjectStoreConfig($config);
-
-		if (!isset($config['arguments']['bucket'])) {
-			$config['arguments']['bucket'] = '';
-		}
-		// put the root FS always in first bucket for multibucket configuration
-		$config['arguments']['bucket'] .= '0';
-
-		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
-		// mount with plain / root object store implementation
-		$config['class'] = ObjectStoreStorage::class;
+	private function getObjectStoreRootMount(IStorageFactory $loader, IObjectStore $objectStore): MountPoint {
+		$arguments = array_merge($this->objectStoreConfig->getObjectStoreArgumentsForRoot(), [
+			'objectstore' => $objectStore,
+		]);
 
-		return new MountPoint($config['class'], '/', $config['arguments'], $loader, null, null, self::class);
+		return new MountPoint(ObjectStoreStorage::class, '/', $arguments, $loader, null, null, self::class);
 	}
 }
diff --git a/lib/private/Files/ObjectStore/HomeObjectStoreStorage.php b/lib/private/Files/ObjectStore/HomeObjectStoreStorage.php
index afc0ac96abc80..73317ef2791f3 100644
--- a/lib/private/Files/ObjectStore/HomeObjectStoreStorage.php
+++ b/lib/private/Files/ObjectStore/HomeObjectStoreStorage.php
@@ -25,7 +25,7 @@
  */
 namespace OC\Files\ObjectStore;
 
-use OC\User\User;
+use OCP\IUser;
 
 class HomeObjectStoreStorage extends ObjectStoreStorage implements \OCP\Files\IHomeStorage {
 
@@ -34,7 +34,7 @@ class HomeObjectStoreStorage extends ObjectStoreStorage implements \OCP\Files\IH
 	 * @param array $params
 	 */
 	public function __construct($params) {
-		if (! isset($params['user']) || ! $params['user'] instanceof User) {
+		if (! isset($params['user']) || ! $params['user'] instanceof IUser) {
 			throw new \Exception('missing user object in parameters');
 		}
 		$this->user = $params['user'];
diff --git a/lib/private/Files/ObjectStore/PrimaryObjectStoreConfig.php b/lib/private/Files/ObjectStore/PrimaryObjectStoreConfig.php
new file mode 100644
index 0000000000000..5fe1a3c447dfc
--- /dev/null
+++ b/lib/private/Files/ObjectStore/PrimaryObjectStoreConfig.php
@@ -0,0 +1,173 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2022 Robin Appelman <robin@icewind.nl>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Files\ObjectStore;
+
+use OCP\Files\ObjectStore\IObjectStore;
+use OCP\IConfig;
+use OCP\IUser;
+use Psr\Log\LoggerInterface;
+
+class PrimaryObjectStoreConfig {
+	private IConfig $config;
+	private LoggerInterface $logger;
+
+	public function __construct(IConfig $config, LoggerInterface $logger) {
+		$this->config = $config;
+		$this->logger = $logger;
+	}
+
+	public function getObjectStoreForRoot(): ?IObjectStore {
+		$config = $this->getObjectStoreConfigForRoot();
+		if (!$config) {
+			return null;
+		}
+
+		if ($config['multibucket']) {
+			if (!isset($config['arguments']['bucket'])) {
+				$config['arguments']['bucket'] = '';
+			}
+
+			// put the root FS always in first bucket for multibucket configuration
+			$config['arguments']['bucket'] .= '0';
+		}
+
+		return new $config['class']($config['arguments']);
+	}
+
+	public function getObjectStoreForUser(IUser $user): ?IObjectStore {
+		$config = $this->getObjectStoreConfigForUser($user);
+		if (!$config) {
+			return null;
+		}
+
+		if ($config['arguments']['multibucket']) {
+			$config['arguments']['bucket'] = $this->getBucketForUser($user, $config);
+		}
+
+		// instantiate object store implementation
+		return new $config['class']($config['arguments']);
+	}
+
+	public function getObjectStoreArgumentsForRoot(): array {
+		$config = $this->getObjectStoreConfigForRoot();
+		if ($config === null) {
+			return [];
+		}
+		return $config['arguments'] ?? [];
+	}
+
+	public function getObjectStoreArgumentsForUser(IUser $user): array {
+		$config = $this->getObjectStoreConfigForUser($user);
+		if ($config === null) {
+			return [];
+		}
+		return $config['arguments'] ?? [];
+	}
+
+	private function getObjectStoreConfigForRoot(): ?array {
+		$configs = $this->getObjectStoreConfig();
+
+		return $configs['root'] ?? $configs['default'];
+	}
+
+	private function getObjectStoreConfigForUser(IUser $user): ?array {
+		$configs = $this->getObjectStoreConfig();
+		$store = $this->config->getUserValue($user->getUID(), 'homeobjectstore', 'objectstore', null);
+
+		if ($store) {
+			return $configs[$store];
+		} else {
+			return $configs['default'];
+		}
+	}
+
+	private function getObjectStoreConfig(): ?array {
+		$objectStore = $this->config->getSystemValue('objectstore', null);
+		$objectStoreMultiBucket = $this->config->getSystemValue('objectstore_multibucket', null);
+
+		// new-style multibucket config uses the same 'objectstore' key but sets `'multibucket' => true`, transparently upgrade older style config
+		if ($objectStoreMultiBucket) {
+			$objectStoreMultiBucket['multibucket'] = true;
+			$objectStore = [
+				'default' => $objectStoreMultiBucket,
+			];
+		}
+		if ($objectStore === null) {
+			return ['default' => null];
+		}
+
+		if (!isset($objectStore['default'])) {
+			$objectStore = [
+				'default' => $objectStore,
+			];
+		}
+
+		foreach ($objectStore as &$config) {
+			if (!isset($config['multibucket'])) {
+				$config['multibucket'] = false;
+			}
+
+			$this->validateObjectStoreConfig($config);
+		}
+
+		return $objectStore;
+	}
+
+	private function validateObjectStoreConfig(array &$config) {
+		if (empty($config['class'])) {
+			$this->logger->error('No class given for objectstore', ['app' => 'files']);
+		}
+		if (!isset($config['arguments'])) {
+			$config['arguments'] = [];
+		}
+
+		// instantiate object store implementation
+		$name = $config['class'];
+		if (strpos($name, 'OCA\\') === 0 && substr_count($name, '\\') >= 2) {
+			$segments = explode('\\', $name);
+			\OC_App::loadApp(strtolower($segments[1]));
+		}
+	}
+
+	private function getBucketForUser(IUser $user, array $config): string {
+		$bucket = $this->config->getUserValue($user->getUID(), 'homeobjectstore', 'bucket', null);
+
+		if ($bucket === null) {
+			/*
+			 * Use any provided bucket argument as prefix
+			 * and add the mapping from username => bucket
+			 */
+			if (!isset($config['arguments']['bucket'])) {
+				$config['arguments']['bucket'] = '';
+			}
+			$mapper = new Mapper($user, $this->config);
+			$numBuckets = isset($config['arguments']['num_buckets']) ? $config['arguments']['num_buckets'] : 64;
+			$bucket = $config['arguments']['bucket'] . $mapper->getBucket($numBuckets);
+
+			$this->config->setUserValue($user->getUID(), 'homeobjectstore', 'bucket', $bucket);
+		}
+
+		return $bucket;
+	}
+}
diff --git a/lib/private/Server.php b/lib/private/Server.php
index 07e90843a9803..9e90ac41d6589 100644
--- a/lib/private/Server.php
+++ b/lib/private/Server.php
@@ -98,6 +98,7 @@
 use OC\Files\Node\HookConnector;
 use OC\Files\Node\LazyRoot;
 use OC\Files\Node\Root;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
 use OC\Files\SetupManager;
 use OC\Files\Storage\StorageFactory;
 use OC\Files\Template\TemplateManager;
@@ -969,10 +970,11 @@ public function __construct($webRoot, \OC\Config $config) {
 
 			$config = $c->get(\OCP\IConfig::class);
 			$logger = $c->get(LoggerInterface::class);
+			$objectStoreConfig = new PrimaryObjectStoreConfig($config, $c->get(LoggerInterface::class));
 			$manager->registerProvider(new CacheMountProvider($config));
 			$manager->registerHomeProvider(new LocalHomeMountProvider());
-			$manager->registerHomeProvider(new ObjectHomeMountProvider($config));
-			$manager->registerRootProvider(new RootMountProvider($config, $c->get(LoggerInterface::class)));
+			$manager->registerHomeProvider(new ObjectHomeMountProvider($objectStoreConfig));
+			$manager->registerRootProvider(new RootMountProvider($objectStoreConfig, $config));
 			$manager->registerRootProvider(new ObjectStorePreviewCacheMountProvider($logger, $config));
 
 			return $manager;
diff --git a/tests/lib/Files/Mount/ObjectHomeMountProviderTest.php b/tests/lib/Files/Mount/ObjectHomeMountProviderTest.php
index 7ce8714012220..2d13cb59b94bc 100644
--- a/tests/lib/Files/Mount/ObjectHomeMountProviderTest.php
+++ b/tests/lib/Files/Mount/ObjectHomeMountProviderTest.php
@@ -3,9 +3,12 @@
 namespace Test\Files\Mount;
 
 use OC\Files\Mount\ObjectHomeMountProvider;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
+use OCP\Files\ObjectStore\IObjectStore;
 use OCP\Files\Storage\IStorageFactory;
 use OCP\IConfig;
 use OCP\IUser;
+use Psr\Log\LoggerInterface;
 
 class ObjectHomeMountProviderTest extends \Test\TestCase {
 
@@ -28,45 +31,53 @@ protected function setUp(): void {
 		$this->user = $this->createMock(IUser::class);
 		$this->loader = $this->createMock(IStorageFactory::class);
 
-		$this->provider = new ObjectHomeMountProvider($this->config);
+		$objectStoreConfig = new PrimaryObjectStoreConfig($this->config, $this->createMock(LoggerInterface::class));
+		$this->provider = new ObjectHomeMountProvider($objectStoreConfig);
 	}
 
 	public function testSingleBucket() {
-		$this->config->expects($this->once())
-			->method('getSystemValue')
-			->with($this->equalTo('objectstore'), '')
-			->willReturn([
-				'class' => 'Test\Files\Mount\FakeObjectStore',
-			]);
-
-		$this->user->expects($this->never())->method($this->anything());
-		$this->loader->expects($this->never())->method($this->anything());
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				if ($key === 'objectstore') {
+					return [
+						'class' => 'Test\Files\Mount\FakeObjectStore',
+						'arguments' => [
+							'foo' => 'bar'
+						],
+					];
+				} else {
+					return $default;
+				}
+			});
 
-		$config = $this->invokePrivate($this->provider, 'getSingleBucketObjectStoreConfig', [$this->user, $this->loader]);
+		$mount = $this->provider->getHomeMountForUser($this->user, $this->loader);
+		$arguments = $this->invokePrivate($mount, 'arguments');
 
-		$this->assertArrayHasKey('class', $config);
-		$this->assertEquals($config['class'], 'Test\Files\Mount\FakeObjectStore');
-		$this->assertArrayHasKey('arguments', $config);
-		$this->assertArrayHasKey('user', $config['arguments']);
-		$this->assertSame($this->user, $config['arguments']['user']);
-		$this->assertArrayHasKey('objectstore', $config['arguments']);
-		$this->assertInstanceOf('Test\Files\Mount\FakeObjectStore', $config['arguments']['objectstore']);
+		$objectStore = $arguments['objectstore'];
+		$this->assertInstanceOf(FakeObjectStore::class, $objectStore);
+		$this->assertEquals(['foo' => 'bar'], $objectStore->getArguments());
 	}
 
 	public function testMultiBucket() {
-		$this->config->expects($this->exactly(2))
-			->method('getSystemValue')
-			->with($this->equalTo('objectstore_multibucket'), '')
-			->willReturn([
-				'class' => 'Test\Files\Mount\FakeObjectStore',
-			]);
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				if ($key === 'objectstore_multibucket') {
+					return [
+						'class' => 'Test\Files\Mount\FakeObjectStore',
+						'arguments' => [
+							'foo' => 'bar'
+						],
+					];
+				} else {
+					return $default;
+				}
+			});
 
 		$this->user->method('getUID')
 			->willReturn('uid');
 		$this->loader->expects($this->never())->method($this->anything());
 
-		$this->config->expects($this->once())
-			->method('getUserValue')
+		$this->config->method('getUserValue')
 			->with(
 				$this->equalTo('uid'),
 				$this->equalTo('homeobjectstore'),
@@ -84,29 +95,29 @@ public function testMultiBucket() {
 				$this->equalTo(null)
 			);
 
-		$config = $this->invokePrivate($this->provider, 'getMultiBucketObjectStoreConfig', [$this->user, $this->loader]);
+		$mount = $this->provider->getHomeMountForUser($this->user, $this->loader);
+		$arguments = $this->invokePrivate($mount, 'arguments');
 
-		$this->assertArrayHasKey('class', $config);
-		$this->assertEquals($config['class'], 'Test\Files\Mount\FakeObjectStore');
-		$this->assertArrayHasKey('arguments', $config);
-		$this->assertArrayHasKey('user', $config['arguments']);
-		$this->assertSame($this->user, $config['arguments']['user']);
-		$this->assertArrayHasKey('objectstore', $config['arguments']);
-		$this->assertInstanceOf('Test\Files\Mount\FakeObjectStore', $config['arguments']['objectstore']);
-		$this->assertArrayHasKey('bucket', $config['arguments']);
-		$this->assertEquals('49', $config['arguments']['bucket']);
+		$objectStore = $arguments['objectstore'];
+		$this->assertInstanceOf(FakeObjectStore::class, $objectStore);
+		$this->assertEquals(['foo' => 'bar', 'bucket' => 49], $objectStore->getArguments());
 	}
 
 	public function testMultiBucketWithPrefix() {
-		$this->config->expects($this->exactly(2))
-			->method('getSystemValue')
-			->with('objectstore_multibucket')
-			->willReturn([
-				'class' => 'Test\Files\Mount\FakeObjectStore',
-				'arguments' => [
-					'bucket' => 'myBucketPrefix',
-				],
-			]);
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				if ($key === 'objectstore_multibucket') {
+					return [
+						'class' => 'Test\Files\Mount\FakeObjectStore',
+						'arguments' => [
+							'foo' => 'bar',
+							'bucket' => 'myBucketPrefix',
+						],
+					];
+				} else {
+					return $default;
+				}
+			});
 
 		$this->user->method('getUID')
 			->willReturn('uid');
@@ -131,29 +142,29 @@ public function testMultiBucketWithPrefix() {
 				$this->equalTo(null)
 			);
 
-		$config = $this->invokePrivate($this->provider, 'getMultiBucketObjectStoreConfig', [$this->user, $this->loader]);
+		$mount = $this->provider->getHomeMountForUser($this->user, $this->loader);
+		$arguments = $this->invokePrivate($mount, 'arguments');
 
-		$this->assertArrayHasKey('class', $config);
-		$this->assertEquals($config['class'], 'Test\Files\Mount\FakeObjectStore');
-		$this->assertArrayHasKey('arguments', $config);
-		$this->assertArrayHasKey('user', $config['arguments']);
-		$this->assertSame($this->user, $config['arguments']['user']);
-		$this->assertArrayHasKey('objectstore', $config['arguments']);
-		$this->assertInstanceOf('Test\Files\Mount\FakeObjectStore', $config['arguments']['objectstore']);
-		$this->assertArrayHasKey('bucket', $config['arguments']);
-		$this->assertEquals('myBucketPrefix49', $config['arguments']['bucket']);
+		$objectStore = $arguments['objectstore'];
+		$this->assertInstanceOf(FakeObjectStore::class, $objectStore);
+		$this->assertEquals(['foo' => 'bar', 'bucket' => 'myBucketPrefix49'], $objectStore->getArguments());
 	}
 
 	public function testMultiBucketBucketAlreadySet() {
-		$this->config->expects($this->once())
-			->method('getSystemValue')
-			->with('objectstore_multibucket')
-			->willReturn([
-				'class' => 'Test\Files\Mount\FakeObjectStore',
-				'arguments' => [
-					'bucket' => 'myBucketPrefix',
-				],
-			]);
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				if ($key === 'objectstore_multibucket') {
+					return [
+						'class' => 'Test\Files\Mount\FakeObjectStore',
+						'arguments' => [
+							'foo' => 'bar',
+							'bucket' => 'myBucketPrefix',
+						],
+					];
+				} else {
+					return $default;
+				}
+			});
 
 		$this->user->method('getUID')
 			->willReturn('uid');
@@ -171,26 +182,29 @@ public function testMultiBucketBucketAlreadySet() {
 		$this->config->expects($this->never())
 			->method('setUserValue');
 
-		$config = $this->invokePrivate($this->provider, 'getMultiBucketObjectStoreConfig', [$this->user, $this->loader]);
+		$mount = $this->provider->getHomeMountForUser($this->user, $this->loader);
+		$arguments = $this->invokePrivate($mount, 'arguments');
 
-		$this->assertArrayHasKey('class', $config);
-		$this->assertEquals($config['class'], 'Test\Files\Mount\FakeObjectStore');
-		$this->assertArrayHasKey('arguments', $config);
-		$this->assertArrayHasKey('user', $config['arguments']);
-		$this->assertSame($this->user, $config['arguments']['user']);
-		$this->assertArrayHasKey('objectstore', $config['arguments']);
-		$this->assertInstanceOf('Test\Files\Mount\FakeObjectStore', $config['arguments']['objectstore']);
-		$this->assertArrayHasKey('bucket', $config['arguments']);
-		$this->assertEquals('awesomeBucket1', $config['arguments']['bucket']);
+		$objectStore = $arguments['objectstore'];
+		$this->assertInstanceOf(FakeObjectStore::class, $objectStore);
+		$this->assertEquals(['foo' => 'bar', 'bucket' => 'awesomeBucket1'], $objectStore->getArguments());
 	}
 
 	public function testMultiBucketConfigFirst() {
-		$this->config->expects($this->exactly(2))
-			->method('getSystemValue')
-			->with('objectstore_multibucket')
-			->willReturn([
-				'class' => 'Test\Files\Mount\FakeObjectStore',
-			]);
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				if ($key === 'objectstore_multibucket') {
+					return [
+						'class' => 'Test\Files\Mount\FakeObjectStore',
+						'arguments' => [
+							'foo' => 'bar',
+							'bucket' => 'myBucketPrefix',
+						],
+					];
+				} else {
+					return $default;
+				}
+			});
 
 		$this->user->method('getUID')
 			->willReturn('uid');
@@ -201,17 +215,20 @@ public function testMultiBucketConfigFirst() {
 	}
 
 	public function testMultiBucketConfigFirstFallBackSingle() {
-		$this->config->expects($this->exactly(2))
-			->method('getSystemValue')
-			->withConsecutive(
-				[$this->equalTo('objectstore_multibucket')],
-				[$this->equalTo('objectstore')],
-			)->willReturnOnConsecutiveCalls(
-				'',
-				[
-					'class' => 'Test\Files\Mount\FakeObjectStore',
-				],
-			);
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				if ($key === 'objectstore') {
+					return [
+						'class' => 'Test\Files\Mount\FakeObjectStore',
+						'arguments' => [
+							'foo' => 'bar',
+							'bucket' => 'myBucketPrefix',
+						],
+					];
+				} else {
+					return $default;
+				}
+			});
 
 		$this->user->method('getUID')
 			->willReturn('uid');
@@ -222,16 +239,17 @@ public function testMultiBucketConfigFirstFallBackSingle() {
 	}
 
 	public function testNoObjectStore() {
-		$this->config->expects($this->exactly(2))
-			->method('getSystemValue')
-			->willReturn('');
+		$this->config->method('getSystemValue')
+			->willReturnCallback(function($key, $default) {
+				return $default;
+			});
 
 		$mount = $this->provider->getHomeMountForUser($this->user, $this->loader);
 		$this->assertNull($mount);
 	}
 }
 
-class FakeObjectStore {
+class FakeObjectStore implements IObjectStore {
 	private $arguments;
 
 	public function __construct(array $arguments) {
@@ -241,4 +259,22 @@ public function __construct(array $arguments) {
 	public function getArguments() {
 		return $this->arguments;
 	}
+
+	public function getStorageId() {
+	}
+
+	public function readObject($urn) {
+	}
+
+	public function writeObject($urn, $stream, string $mimetype = null) {
+	}
+
+	public function deleteObject($urn) {
+	}
+
+	public function objectExists($urn) {
+	}
+
+	public function copyObject($from, $to) {
+	}
 }
diff --git a/tests/lib/Files/Mount/RootMountProviderTest.php b/tests/lib/Files/Mount/RootMountProviderTest.php
index e5eaabf93bee4..f6379461ddbc2 100644
--- a/tests/lib/Files/Mount/RootMountProviderTest.php
+++ b/tests/lib/Files/Mount/RootMountProviderTest.php
@@ -25,6 +25,7 @@
 
 use OC\Files\Mount\RootMountProvider;
 use OC\Files\ObjectStore\ObjectStoreStorage;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
 use OC\Files\ObjectStore\S3;
 use OC\Files\Storage\LocalRootStorage;
 use OC\Files\Storage\StorageFactory;
@@ -55,8 +56,8 @@ private function getConfig(array $systemConfig): IConfig {
 
 	private function getProvider(array $systemConfig): RootMountProvider {
 		$config = $this->getConfig($systemConfig);
-		$provider = new RootMountProvider($config, $this->createMock(LoggerInterface::class));
-		return $provider;
+		$objectStoreConfig = new PrimaryObjectStoreConfig($config, $this->createMock(LoggerInterface::class));
+		return new RootMountProvider($objectStoreConfig, $config);
 	}
 
 	public function testLocal() {
diff --git a/tests/lib/TestCase.php b/tests/lib/TestCase.php
index 256fb95a85be1..b637ab844a3cd 100644
--- a/tests/lib/TestCase.php
+++ b/tests/lib/TestCase.php
@@ -30,6 +30,7 @@
 use OC\Files\Mount\CacheMountProvider;
 use OC\Files\Mount\LocalHomeMountProvider;
 use OC\Files\Mount\RootMountProvider;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
 use OC\Files\SetupManager;
 use OC\Template\Base;
 use OCP\Command\IBus;
@@ -295,7 +296,8 @@ public static function tearDownAfterClass(): void {
 		$config = \OC::$server->get(IConfig::class);
 		$mountProviderCollection->registerProvider(new CacheMountProvider($config));
 		$mountProviderCollection->registerHomeProvider(new LocalHomeMountProvider());
-		$mountProviderCollection->registerRootProvider(new RootMountProvider($config, \OC::$server->get(LoggerInterface::class)));
+		$objectStoreConfig = new PrimaryObjectStoreConfig($config, \OC::$server->get(LoggerInterface::class));
+		$mountProviderCollection->registerRootProvider(new RootMountProvider($objectStoreConfig, $config));
 
 		$setupManager->setupRoot();