9 files changed, 911 insertions, 0 deletions
diff --git a/lib/private/Files/Mount/CacheMountProvider.php b/lib/private/Files/Mount/CacheMountProvider.php
new file mode 100644
index 00000000000..27c7eec9da3
--- /dev/null
+++ b/lib/private/Files/Mount/CacheMountProvider.php
@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Files\Mount;
+
+use OCP\Files\Config\IMountProvider;
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IConfig;
+use OCP\IUser;
+
+/**
+ * Mount provider for custom cache storages
+ */
+class CacheMountProvider implements IMountProvider {
+	/**
+	 * @var IConfig
+	 */
+	private $config;
+
+	/**
+	 * ObjectStoreHomeMountProvider constructor.
+	 *
+	 * @param IConfig $config
+	 */
+	public function __construct(IConfig $config) {
+		$this->config = $config;
+	}
+
+	/**
+	 * Get the cache mount for a user
+	 *
+	 * @param IUser $user
+	 * @param IStorageFactory $loader
+	 * @return \OCP\Files\Mount\IMountPoint[]
+	 */
+	public function getMountsForUser(IUser $user, IStorageFactory $loader) {
+		$cacheBaseDir = $this->config->getSystemValueString('cache_path', '');
+		if ($cacheBaseDir !== '') {
+			$cacheDir = rtrim($cacheBaseDir, '/') . '/' . $user->getUID();
+			if (!file_exists($cacheDir)) {
+				mkdir($cacheDir, 0770, true);
+				mkdir($cacheDir . '/uploads', 0770, true);
+			}
+
+			return [
+				new MountPoint('\OC\Files\Storage\Local', '/' . $user->getUID() . '/cache', ['datadir' => $cacheDir], $loader, null, null, self::class),
+				new MountPoint('\OC\Files\Storage\Local', '/' . $user->getUID() . '/uploads', ['datadir' => $cacheDir . '/uploads'], $loader, null, null, self::class)
+			];
+		} else {
+			return [];
+		}
+	}
+}
diff --git a/lib/private/Files/Mount/HomeMountPoint.php b/lib/private/Files/Mount/HomeMountPoint.php
new file mode 100644
index 00000000000..5a648f08c89
--- /dev/null
+++ b/lib/private/Files/Mount/HomeMountPoint.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2023 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Files\Mount;
+
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IUser;
+
+class HomeMountPoint extends MountPoint {
+	private IUser $user;
+
+	public function __construct(
+		IUser $user,
+		$storage,
+		string $mountpoint,
+		?array $arguments = null,
+		?IStorageFactory $loader = null,
+		?array $mountOptions = null,
+		?int $mountId = null,
+		?string $mountProvider = null,
+	) {
+		parent::__construct($storage, $mountpoint, $arguments, $loader, $mountOptions, $mountId, $mountProvider);
+		$this->user = $user;
+	}
+
+	public function getUser(): IUser {
+		return $this->user;
+	}
+}
diff --git a/lib/private/Files/Mount/LocalHomeMountProvider.php b/lib/private/Files/Mount/LocalHomeMountProvider.php
new file mode 100644
index 00000000000..a2b3d3b2a99
--- /dev/null
+++ b/lib/private/Files/Mount/LocalHomeMountProvider.php
@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Files\Mount;
+
+use OCP\Files\Config\IHomeMountProvider;
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IUser;
+
+/**
+ * Mount provider for regular posix home folders
+ */
+class LocalHomeMountProvider implements IHomeMountProvider {
+	/**
+	 * Get the cache mount for a user
+	 *
+	 * @param IUser $user
+	 * @param IStorageFactory $loader
+	 * @return \OCP\Files\Mount\IMountPoint|null
+	 */
+	public function getHomeMountForUser(IUser $user, IStorageFactory $loader) {
+		$arguments = ['user' => $user];
+		return new HomeMountPoint($user, '\OC\Files\Storage\Home', '/' . $user->getUID(), $arguments, $loader, null, null, self::class);
+	}
+}
diff --git a/lib/private/Files/Mount/Manager.php b/lib/private/Files/Mount/Manager.php
new file mode 100644
index 00000000000..55de488c726
--- /dev/null
+++ b/lib/private/Files/Mount/Manager.php
@@ -0,0 +1,235 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Files\Mount;
+
+use OC\Files\Filesystem;
+use OC\Files\SetupManager;
+use OC\Files\SetupManagerFactory;
+use OCP\Cache\CappedMemoryCache;
+use OCP\Files\Config\ICachedMountInfo;
+use OCP\Files\Mount\IMountManager;
+use OCP\Files\Mount\IMountPoint;
+use OCP\Files\NotFoundException;
+
+class Manager implements IMountManager {
+	/** @var MountPoint[] */
+	private array $mounts = [];
+	/** @var CappedMemoryCache<IMountPoint> */
+	private CappedMemoryCache $pathCache;
+	/** @var CappedMemoryCache<IMountPoint[]> */
+	private CappedMemoryCache $inPathCache;
+	private SetupManager $setupManager;
+
+	public function __construct(SetupManagerFactory $setupManagerFactory) {
+		$this->pathCache = new CappedMemoryCache();
+		$this->inPathCache = new CappedMemoryCache();
+		$this->setupManager = $setupManagerFactory->create($this);
+	}
+
+	/**
+	 * @param IMountPoint $mount
+	 */
+	public function addMount(IMountPoint $mount) {
+		$this->mounts[$mount->getMountPoint()] = $mount;
+		$this->pathCache->clear();
+		$this->inPathCache->clear();
+	}
+
+	/**
+	 * @param string $mountPoint
+	 */
+	public function removeMount(string $mountPoint) {
+		$mountPoint = Filesystem::normalizePath($mountPoint);
+		if (\strlen($mountPoint) > 1) {
+			$mountPoint .= '/';
+		}
+		unset($this->mounts[$mountPoint]);
+		$this->pathCache->clear();
+		$this->inPathCache->clear();
+	}
+
+	/**
+	 * @param string $mountPoint
+	 * @param string $target
+	 */
+	public function moveMount(string $mountPoint, string $target) {
+		$this->mounts[$target] = $this->mounts[$mountPoint];
+		unset($this->mounts[$mountPoint]);
+		$this->pathCache->clear();
+		$this->inPathCache->clear();
+	}
+
+	/**
+	 * Find the mount for $path
+	 *
+	 * @param string $path
+	 * @return IMountPoint
+	 */
+	public function find(string $path): IMountPoint {
+		$this->setupManager->setupForPath($path);
+		$path = Filesystem::normalizePath($path);
+
+		if (isset($this->pathCache[$path])) {
+			return $this->pathCache[$path];
+		}
+
+
+
+		if (count($this->mounts) === 0) {
+			$this->setupManager->setupRoot();
+			if (count($this->mounts) === 0) {
+				throw new \Exception('No mounts even after explicitly setting up the root mounts');
+			}
+		}
+
+		$current = $path;
+		while (true) {
+			$mountPoint = $current . '/';
+			if (isset($this->mounts[$mountPoint])) {
+				$this->pathCache[$path] = $this->mounts[$mountPoint];
+				return $this->mounts[$mountPoint];
+			} elseif ($current === '') {
+				break;
+			}
+
+			$current = dirname($current);
+			if ($current === '.' || $current === '/') {
+				$current = '';
+			}
+		}
+
+		throw new NotFoundException('No mount for path ' . $path . ' existing mounts (' . count($this->mounts) . '): ' . implode(',', array_keys($this->mounts)));
+	}
+
+	/**
+	 * Find all mounts in $path
+	 *
+	 * @param string $path
+	 * @return IMountPoint[]
+	 */
+	public function findIn(string $path): array {
+		$this->setupManager->setupForPath($path, true);
+		$path = $this->formatPath($path);
+
+		if (isset($this->inPathCache[$path])) {
+			return $this->inPathCache[$path];
+		}
+
+		$result = [];
+		$pathLength = \strlen($path);
+		$mountPoints = array_keys($this->mounts);
+		foreach ($mountPoints as $mountPoint) {
+			if (substr($mountPoint, 0, $pathLength) === $path && \strlen($mountPoint) > $pathLength) {
+				$result[] = $this->mounts[$mountPoint];
+			}
+		}
+
+		$this->inPathCache[$path] = $result;
+		return $result;
+	}
+
+	public function clear() {
+		$this->mounts = [];
+		$this->pathCache->clear();
+		$this->inPathCache->clear();
+	}
+
+	/**
+	 * Find mounts by storage id
+	 *
+	 * @param string $id
+	 * @return IMountPoint[]
+	 */
+	public function findByStorageId(string $id): array {
+		if (\strlen($id) > 64) {
+			$id = md5($id);
+		}
+		$result = [];
+		foreach ($this->mounts as $mount) {
+			if ($mount->getStorageId() === $id) {
+				$result[] = $mount;
+			}
+		}
+		return $result;
+	}
+
+	/**
+	 * @return IMountPoint[]
+	 */
+	public function getAll(): array {
+		return $this->mounts;
+	}
+
+	/**
+	 * Find mounts by numeric storage id
+	 *
+	 * @param int $id
+	 * @return IMountPoint[]
+	 */
+	public function findByNumericId(int $id): array {
+		$result = [];
+		foreach ($this->mounts as $mount) {
+			if ($mount->getNumericStorageId() === $id) {
+				$result[] = $mount;
+			}
+		}
+		return $result;
+	}
+
+	/**
+	 * @param string $path
+	 * @return string
+	 */
+	private function formatPath(string $path): string {
+		$path = Filesystem::normalizePath($path);
+		if (\strlen($path) > 1) {
+			$path .= '/';
+		}
+		return $path;
+	}
+
+	public function getSetupManager(): SetupManager {
+		return $this->setupManager;
+	}
+
+	/**
+	 * Return all mounts in a path from a specific mount provider
+	 *
+	 * @param string $path
+	 * @param string[] $mountProviders
+	 * @return MountPoint[]
+	 */
+	public function getMountsByMountProvider(string $path, array $mountProviders) {
+		$this->getSetupManager()->setupForProvider($path, $mountProviders);
+		if (in_array('', $mountProviders)) {
+			return $this->mounts;
+		} else {
+			return array_filter($this->mounts, function ($mount) use ($mountProviders) {
+				return in_array($mount->getMountProvider(), $mountProviders);
+			});
+		}
+	}
+
+	/**
+	 * Return the mount matching a cached mount info (or mount file info)
+	 *
+	 * @param ICachedMountInfo $info
+	 *
+	 * @return IMountPoint|null
+	 */
+	public function getMountFromMountInfo(ICachedMountInfo $info): ?IMountPoint {
+		$this->setupManager->setupForPath($info->getMountPoint());
+		foreach ($this->mounts as $mount) {
+			if ($mount->getMountPoint() === $info->getMountPoint()) {
+				return $mount;
+			}
+		}
+		return null;
+	}
+}
diff --git a/lib/private/Files/Mount/MountPoint.php b/lib/private/Files/Mount/MountPoint.php
new file mode 100644
index 00000000000..bab2dc8e4bd
--- /dev/null
+++ b/lib/private/Files/Mount/MountPoint.php
@@ -0,0 +1,293 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Files\Mount;
+
+use OC\Files\Filesystem;
+use OC\Files\Storage\Storage;
+use OC\Files\Storage\StorageFactory;
+use OCP\Files\Mount\IMountPoint;
+use OCP\Files\Storage\IStorageFactory;
+use Psr\Log\LoggerInterface;
+
+class MountPoint implements IMountPoint {
+	/**
+	 * @var \OC\Files\Storage\Storage|null $storage
+	 */
+	protected $storage = null;
+	protected $class;
+	protected $storageId;
+	protected $numericStorageId = null;
+	protected $rootId = null;
+
+	/**
+	 * Configuration options for the storage backend
+	 *
+	 * @var array
+	 */
+	protected $arguments = [];
+	protected $mountPoint;
+
+	/**
+	 * Mount specific options
+	 *
+	 * @var array
+	 */
+	protected $mountOptions = [];
+
+	/**
+	 * @var \OC\Files\Storage\StorageFactory $loader
+	 */
+	private $loader;
+
+	/**
+	 * Specified whether the storage is invalid after failing to
+	 * instantiate it.
+	 *
+	 * @var bool
+	 */
+	private $invalidStorage = false;
+
+	/** @var int|null */
+	protected $mountId;
+
+	/** @var string */
+	protected $mountProvider;
+
+	/**
+	 * @param string|\OC\Files\Storage\Storage $storage
+	 * @param string $mountpoint
+	 * @param array $arguments (optional) configuration for the storage backend
+	 * @param \OCP\Files\Storage\IStorageFactory $loader
+	 * @param array $mountOptions mount specific options
+	 * @param int|null $mountId
+	 * @param string|null $mountProvider
+	 * @throws \Exception
+	 */
+	public function __construct(
+		$storage,
+		string $mountpoint,
+		?array $arguments = null,
+		?IStorageFactory $loader = null,
+		?array $mountOptions = null,
+		?int $mountId = null,
+		?string $mountProvider = null,
+	) {
+		if (is_null($arguments)) {
+			$arguments = [];
+		}
+		if (is_null($loader)) {
+			$this->loader = new StorageFactory();
+		} else {
+			$this->loader = $loader;
+		}
+
+		if (!is_null($mountOptions)) {
+			$this->mountOptions = $mountOptions;
+		}
+
+		$mountpoint = $this->formatPath($mountpoint);
+		$this->mountPoint = $mountpoint;
+		$this->mountId = $mountId;
+		if ($storage instanceof Storage) {
+			$this->class = get_class($storage);
+			$this->storage = $this->loader->wrap($this, $storage);
+		} else {
+			// Update old classes to new namespace
+			if (str_contains($storage, 'OC_Filestorage_')) {
+				$storage = '\OC\Files\Storage\\' . substr($storage, 15);
+			}
+			$this->class = $storage;
+			$this->arguments = $arguments;
+		}
+		if ($mountProvider) {
+			if (strlen($mountProvider) > 128) {
+				throw new \Exception("Mount provider $mountProvider name exceeds the limit of 128 characters");
+			}
+		}
+		$this->mountProvider = $mountProvider ?? '';
+	}
+
+	/**
+	 * get complete path to the mount point, relative to data/
+	 *
+	 * @return string
+	 */
+	public function getMountPoint() {
+		return $this->mountPoint;
+	}
+
+	/**
+	 * Sets the mount point path, relative to data/
+	 *
+	 * @param string $mountPoint new mount point
+	 */
+	public function setMountPoint($mountPoint) {
+		$this->mountPoint = $this->formatPath($mountPoint);
+	}
+
+	/**
+	 * create the storage that is mounted
+	 */
+	private function createStorage() {
+		if ($this->invalidStorage) {
+			return;
+		}
+
+		if (class_exists($this->class)) {
+			try {
+				$class = $this->class;
+				// prevent recursion by setting the storage before applying wrappers
+				$this->storage = new $class($this->arguments);
+				$this->storage = $this->loader->wrap($this, $this->storage);
+			} catch (\Exception $exception) {
+				$this->storage = null;
+				$this->invalidStorage = true;
+				if ($this->mountPoint === '/') {
+					// the root storage could not be initialized, show the user!
+					throw new \Exception('The root storage could not be initialized. Please contact your local administrator.', $exception->getCode(), $exception);
+				} else {
+					\OC::$server->get(LoggerInterface::class)->error($exception->getMessage(), ['exception' => $exception]);
+				}
+				return;
+			}
+		} else {
+			\OC::$server->get(LoggerInterface::class)->error('Storage backend ' . $this->class . ' not found', ['app' => 'core']);
+			$this->invalidStorage = true;
+			return;
+		}
+	}
+
+	/**
+	 * @return \OC\Files\Storage\Storage|null
+	 */
+	public function getStorage() {
+		if (is_null($this->storage)) {
+			$this->createStorage();
+		}
+		return $this->storage;
+	}
+
+	/**
+	 * @return string|null
+	 */
+	public function getStorageId() {
+		if (!$this->storageId) {
+			$storage = $this->getStorage();
+			if (is_null($storage)) {
+				return null;
+			}
+			$this->storageId = $storage->getId();
+			if (strlen($this->storageId) > 64) {
+				$this->storageId = md5($this->storageId);
+			}
+		}
+		return $this->storageId;
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getNumericStorageId() {
+		if (is_null($this->numericStorageId)) {
+			$storage = $this->getStorage();
+			if (is_null($storage)) {
+				return -1;
+			}
+			$this->numericStorageId = $storage->getCache()->getNumericStorageId();
+		}
+		return $this->numericStorageId;
+	}
+
+	/**
+	 * @param string $path
+	 * @return string
+	 */
+	public function getInternalPath($path) {
+		$path = Filesystem::normalizePath($path, true, false, true);
+		if ($this->mountPoint === $path or $this->mountPoint . '/' === $path) {
+			$internalPath = '';
+		} else {
+			$internalPath = substr($path, strlen($this->mountPoint));
+		}
+		// substr returns false instead of an empty string, we always want a string
+		return (string)$internalPath;
+	}
+
+	/**
+	 * @param string $path
+	 * @return string
+	 */
+	private function formatPath($path) {
+		$path = Filesystem::normalizePath($path);
+		if (strlen($path) > 1) {
+			$path .= '/';
+		}
+		return $path;
+	}
+
+	/**
+	 * @param callable $wrapper
+	 */
+	public function wrapStorage($wrapper) {
+		$storage = $this->getStorage();
+		// storage can be null if it couldn't be initialized
+		if ($storage != null) {
+			$this->storage = $wrapper($this->mountPoint, $storage, $this);
+		}
+	}
+
+	/**
+	 * Get a mount option
+	 *
+	 * @param string $name Name of the mount option to get
+	 * @param mixed $default Default value for the mount option
+	 * @return mixed
+	 */
+	public function getOption($name, $default) {
+		return $this->mountOptions[$name] ?? $default;
+	}
+
+	/**
+	 * Get all options for the mount
+	 *
+	 * @return array
+	 */
+	public function getOptions() {
+		return $this->mountOptions;
+	}
+
+	/**
+	 * Get the file id of the root of the storage
+	 *
+	 * @return int
+	 */
+	public function getStorageRootId() {
+		if (is_null($this->rootId) || $this->rootId === -1) {
+			$storage = $this->getStorage();
+			// if we can't create the storage return -1 as root id, this is then handled the same as if the root isn't scanned yet
+			if ($storage === null) {
+				$this->rootId = -1;
+			} else {
+				$this->rootId = (int)$storage->getCache()->getId('');
+			}
+		}
+		return $this->rootId;
+	}
+
+	public function getMountId() {
+		return $this->mountId;
+	}
+
+	public function getMountType() {
+		return '';
+	}
+
+	public function getMountProvider(): string {
+		return $this->mountProvider;
+	}
+}
diff --git a/lib/private/Files/Mount/MoveableMount.php b/lib/private/Files/Mount/MoveableMount.php
new file mode 100644
index 00000000000..755733bf651
--- /dev/null
+++ b/lib/private/Files/Mount/MoveableMount.php
@@ -0,0 +1,30 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Files\Mount;
+
+use OCP\Files\Mount\IMovableMount;
+
+/**
+ * Defines the mount point to be (re)moved by the user
+ */
+interface MoveableMount extends IMovableMount {
+	/**
+	 * Move the mount point to $target
+	 *
+	 * @param string $target the target mount point
+	 * @return bool
+	 */
+	public function moveMount($target);
+
+	/**
+	 * Remove the mount points
+	 *
+	 * @return bool
+	 */
+	public function removeMount();
+}
diff --git a/lib/private/Files/Mount/ObjectHomeMountProvider.php b/lib/private/Files/Mount/ObjectHomeMountProvider.php
new file mode 100644
index 00000000000..4b088f2c808
--- /dev/null
+++ b/lib/private/Files/Mount/ObjectHomeMountProvider.php
@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+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\IUser;
+
+/**
+ * Mount provider for object store home storages
+ */
+class ObjectHomeMountProvider implements IHomeMountProvider {
+	public function __construct(
+		private PrimaryObjectStoreConfig $objectStoreConfig,
+	) {
+	}
+
+	/**
+	 * Get the home mount for a user
+	 *
+	 * @param IUser $user
+	 * @param IStorageFactory $loader
+	 * @return ?IMountPoint
+	 */
+	public function getHomeMountForUser(IUser $user, IStorageFactory $loader): ?IMountPoint {
+		$objectStoreConfig = $this->objectStoreConfig->getObjectStoreConfigForUser($user);
+		if ($objectStoreConfig === null) {
+			return null;
+		}
+		$arguments = array_merge($objectStoreConfig['arguments'], [
+			'objectstore' => $this->objectStoreConfig->buildObjectStore($objectStoreConfig),
+			'user' => $user,
+		]);
+
+		return new HomeMountPoint($user, HomeObjectStoreStorage::class, '/' . $user->getUID(), $arguments, $loader, null, null, self::class);
+	}
+}
diff --git a/lib/private/Files/Mount/ObjectStorePreviewCacheMountProvider.php b/lib/private/Files/Mount/ObjectStorePreviewCacheMountProvider.php
new file mode 100644
index 00000000000..1546ef98f50
--- /dev/null
+++ b/lib/private/Files/Mount/ObjectStorePreviewCacheMountProvider.php
@@ -0,0 +1,138 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\Files\Mount;
+
+use OC\Files\ObjectStore\AppdataPreviewObjectStoreStorage;
+use OC\Files\ObjectStore\ObjectStoreStorage;
+use OC\Files\Storage\Wrapper\Jail;
+use OCP\Files\Config\IRootMountProvider;
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IConfig;
+use Psr\Log\LoggerInterface;
+
+/**
+ * Mount provider for object store app data folder for previews
+ */
+class ObjectStorePreviewCacheMountProvider implements IRootMountProvider {
+	private LoggerInterface $logger;
+	/** @var IConfig */
+	private $config;
+
+	public function __construct(LoggerInterface $logger, IConfig $config) {
+		$this->logger = $logger;
+		$this->config = $config;
+	}
+
+	/**
+	 * @return MountPoint[]
+	 * @throws \Exception
+	 */
+	public function getRootMounts(IStorageFactory $loader): array {
+		if (!is_array($this->config->getSystemValue('objectstore_multibucket'))) {
+			return [];
+		}
+		if ($this->config->getSystemValue('objectstore.multibucket.preview-distribution', false) !== true) {
+			return [];
+		}
+
+		$instanceId = $this->config->getSystemValueString('instanceid', '');
+		$mountPoints = [];
+		$directoryRange = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'];
+		$i = 0;
+		foreach ($directoryRange as $parent) {
+			foreach ($directoryRange as $child) {
+				$mountPoints[] = new MountPoint(
+					AppdataPreviewObjectStoreStorage::class,
+					'/appdata_' . $instanceId . '/preview/' . $parent . '/' . $child,
+					$this->getMultiBucketObjectStore($i),
+					$loader,
+					null,
+					null,
+					self::class
+				);
+				$i++;
+			}
+		}
+
+		$rootStorageArguments = $this->getMultiBucketObjectStoreForRoot();
+		$fakeRootStorage = new ObjectStoreStorage($rootStorageArguments);
+		$fakeRootStorageJail = new Jail([
+			'storage' => $fakeRootStorage,
+			'root' => '/appdata_' . $instanceId . '/preview',
+		]);
+
+		// add a fallback location to be able to fetch existing previews from the old bucket
+		$mountPoints[] = new MountPoint(
+			$fakeRootStorageJail,
+			'/appdata_' . $instanceId . '/preview/old-multibucket',
+			null,
+			$loader,
+			null,
+			null,
+			self::class
+		);
+
+		return $mountPoints;
+	}
+
+	protected function getMultiBucketObjectStore(int $number): array {
+		$config = $this->config->getSystemValue('objectstore_multibucket');
+
+		// sanity checks
+		if (empty($config['class'])) {
+			$this->logger->error('No class given for objectstore', ['app' => 'files']);
+		}
+		if (!isset($config['arguments'])) {
+			$config['arguments'] = [];
+		}
+
+		/*
+		 * Use any provided bucket argument as prefix
+		 * and add the mapping from parent/child => bucket
+		 */
+		if (!isset($config['arguments']['bucket'])) {
+			$config['arguments']['bucket'] = '';
+		}
+
+		$config['arguments']['bucket'] .= "-preview-$number";
+
+		// instantiate object store implementation
+		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
+
+		$config['arguments']['internal-id'] = $number;
+
+		return $config['arguments'];
+	}
+
+	protected function getMultiBucketObjectStoreForRoot(): array {
+		$config = $this->config->getSystemValue('objectstore_multibucket');
+
+		// sanity checks
+		if (empty($config['class'])) {
+			$this->logger->error('No class given for objectstore', ['app' => 'files']);
+		}
+		if (!isset($config['arguments'])) {
+			$config['arguments'] = [];
+		}
+
+		/*
+		 * Use any provided bucket argument as prefix
+		 * and add the mapping from parent/child => bucket
+		 */
+		if (!isset($config['arguments']['bucket'])) {
+			$config['arguments']['bucket'] = '';
+		}
+		$config['arguments']['bucket'] .= '0';
+
+		// instantiate object store implementation
+		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
+
+		return $config['arguments'];
+	}
+}
diff --git a/lib/private/Files/Mount/RootMountProvider.php b/lib/private/Files/Mount/RootMountProvider.php
new file mode 100644
index 00000000000..5e0c924ad38
--- /dev/null
+++ b/lib/private/Files/Mount/RootMountProvider.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2022 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Files\Mount;
+
+use OC;
+use OC\Files\ObjectStore\ObjectStoreStorage;
+use OC\Files\ObjectStore\PrimaryObjectStoreConfig;
+use OC\Files\Storage\LocalRootStorage;
+use OCP\Files\Config\IRootMountProvider;
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IConfig;
+
+class RootMountProvider implements IRootMountProvider {
+	private PrimaryObjectStoreConfig $objectStoreConfig;
+	private IConfig $config;
+
+	public function __construct(PrimaryObjectStoreConfig $objectStoreConfig, IConfig $config) {
+		$this->objectStoreConfig = $objectStoreConfig;
+		$this->config = $config;
+	}
+
+	public function getRootMounts(IStorageFactory $loader): array {
+		$objectStoreConfig = $this->objectStoreConfig->getObjectStoreConfigForRoot();
+
+		if ($objectStoreConfig) {
+			return [$this->getObjectStoreRootMount($loader, $objectStoreConfig)];
+		} else {
+			return [$this->getLocalRootMount($loader)];
+		}
+	}
+
+	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 $objectStoreConfig): MountPoint {
+		$arguments = array_merge($objectStoreConfig['arguments'], [
+			'objectstore' => $this->objectStoreConfig->buildObjectStore($objectStoreConfig),
+		]);
+
+		return new MountPoint(ObjectStoreStorage::class, '/', $arguments, $loader, null, null, self::class);
+	}
+}