make nextcloud create external storage

modules/services/nextcloud-server.nix

@@ -685,7 +685,11 @@ in
       # not loading to realize those scripts are inserted by extensions. Doh.
       services.nextcloud = {
         enable = true;
-        package = nextcloudPkg;
+        package = nextcloudPkg.overrideAttrs (old: {
+          patches = [
+            ../../patches/nextcloudexternalstorage.patch
+          ];
+        });
 
         datadir = cfg.dataDir;
 

modules/services/nextcloud-server/docs/default.md

@@ -457,6 +457,12 @@ which is well suited for randomly accessing small files like thumbnails.
 On the other side, a spinning hard drive can store more data
 which is well suited for storing user data.
 
+This Nextcloud module includes a patch that allows the external storage
+to actually create the local path. Normally, when login in for the first time,
+the user will be greeted with an error saying the external storage path does
+not exist. One must then create it manually. With this patch, Nextcloud
+creates the path.
+
 ### Enable OnlyOffice App {#services-nextcloudserver-usage-onlyoffice}
 
 The following snippet installs and enables the [Only

patches/nextcloudexternalstorage.patch

@@ -0,0 +1,21 @@
+diff --git a/lib/private/Files/Storage/Local.php b/lib/private/Files/Storage/Local.php
+index 8fec24996891f..57b2980f1a43f 100644
+--- a/lib/private/Files/Storage/Local.php
++++ b/lib/private/Files/Storage/Local.php
+@@ -101,9 +101,13 @@ public function __construct($arguments) {
+ 		$this->unlinkOnTruncate = $this->config->getSystemValueBool('localstorage.unlink_on_truncate', false);
+ 
+ 		if (isset($arguments['isExternal']) && $arguments['isExternal'] && !$this->stat('')) {
+-			// data dir not accessible or available, can happen when using an external storage of type Local
+-			// on an unmounted system mount point
+-			throw new StorageNotAvailableException('Local storage path does not exist "' . $this->getSourcePath('') . '"');
++
++            if (!$this->mkdir('')) {
++                // data dir not accessible or available, can happen when using an external storage of type Local
++                // on an unmounted system mount point
++                throw new StorageNotAvailableException('Local storage path does not exist and could not create it "' . $this->getSourcePath('') . '"');
++            }
++            \OC::$server->get(LoggerInterface::class)->warning('created local storage path ' . $this->getSourcePath(''), ['app' => 'core']);
+ 		}
+ 	}
+